1. Historical review of malarial control in southern African with emphasis on the use of indoor residual house-spraying
2. Malaria control by residual insecticide spraying in Chingola and Chiliabombwe, Copperbelt Province, Zambia.
3. Too poor to pay: Charging for insecticide-treated bednets in highland Kenya.
4. Combating malaria vectors in Africa : Current directions of research
5. The economic payoffs of integrated malaria control in the Zambian copperbelt between 1930 and 1950.
6. Advantages of larval control for African malaria vectors: Low mobility and behavioral responsiveness of immature mosquito stages allow high effective coverage.
7. A comparative cost analysis of insecticide-treated nets and indoor residual spraying in highland Kenya.
8. Malaria prevention in highland Kenya: Indoor residual house-spraying vs. insecticide-treated bednets.
9. Impact of the Malaria Control Campaign (1993-1998) in the highlands of Madagascar: Parasitological and entomological data.
10. Malaria control: Two years' use of insecticide-treated bednets compared with insecticide house spraying in KwaZulu-Natal.
11. Malaria in the highlands of Madagascar after five years of indoor house spraying of DDT.
12. Intermittent treatment for malaria and anemia control at time of routine vaccinations in Tanzanian infants: A randomized, placebo-controlled trial.
13. Comparison of house spraying and insecticide-treated nets for malaria control.
14. Determinants of malaria in Africa.
15. Malaria control and the paradox of DDT.
16. Implementation of malaria control.
17. Malaria control priorities and constraints.
18. The complexity of the malaria vectorial system in Africa.
19. Opportunities, problems and perspectives for malaria control in sub-Saharan Africa.
20. The malaria challenge in the 21stcentury: Perspectives for Africa.
21. Malaria mortality and morbidity in Africa.
22. Cost-effectiveness of malaria control in sub-Saharan Africa.
23. DDT, dieldrin, and pyrethroid insecticide resistance in African malaria vector mosquitoes: An historical review and implications for future malaria control in southern Africa.
24. Malaria in the African highlands: Past, present, and future.
25. A comparison of use of a pyrethroid either for house spraying or for bednet treatment against malaria vectors.
26. Malaria transmission and vector control.
27. Lessons learned from applied field research activities in Africa during the malaria eradication era.
1) Lengeler, C.; M.L.H. Mabaso; B. Sharp. Historical review of malarial control in southern African with emphasis on the use of indoor residual house-spraying. Tropical Medicine and International Health. August 2004. Vol. 9 No. 8 pp 846–856.
PANNA summary: The researchers investigate the malarial situation before and after the introduction of indoor residual insecticide spraying (IRS) within several countries in Africa . Following the use of IRS within the respective countries, those that were able to develop a National Malaria Control Programme during the phase out of DDT and had strengthened their human and organizational assets made dramatic improvements in malarial control.
Abstract: Indoor residual house-spraying (IRS) mainly with dichlorodiphenyltrichloroethane (DDT) was the principal method by which malaria was eradicated or greatly reduced in many countries in the world between the 1940s and 1960s. In sub-Saharan Africa early malarial eradication pilot projects also showed that malaria is highly responsive to vector control by IRS but transmission could not be interrupted in the endemic tropical and lowland areas. As a result IRS was not taken to scale in most endemic areas of the continent with the exception of southern Africa and some island countries such as Reunion, Mayotte, Zanzibar , Cape Verde and Sao Tome . In southern Africa large-scale malarial control operations based on IRS with DDT and benzene hexachloride (BHC) were initiated in a number of countries to varying degrees. The objective of this review was to investigate the malarial situation before and after the introduction of indoor residual insecticide spraying in South Africa , Swaziland , Botswana , Namibia , Zimbabwe and Mozambique using historical malarial data and related information collected from National Malaria Control Programmes, national archives and libraries, as well as academic institutions in the respective countries. Immediately after the inception of IRS with insecticides, dramatic reductions in malaria and its vectors were recorded. Countries that developed National Malaria Control Programmes during this phase and had built up human and organizational resources made significant advances towards malarial control. Malaria was reduced from hyper- to meso-endemicity and from meso- to hypo-endemicity and in certain instances to complete eradication. Data are presented on the effectiveness of IRS as a malarial control tool in six southern African countries. Recent trends in and challenges to malarial control in the region are also discussed.
2) Sharp, B. and P. van Wyk, J. B. Sikasote, P. Banda, and I. Kleinschmidt. Malaria control by residual insecticide spraying in Chingola and Chililabombwe, Copperbelt Province, Zambia. Tropical Medicine and International Health, Vol 7, no 9, pp 732-6. September 2002.
PANNA summary: This study surveyed parasite prevalence and the knowledge, attitudes and practices regarding malaria of Chingola and Chililabombwe towns after Konkola Copper Mines initiated a malaria control program there, spraying all houses in the area with either DDT or one of two synthetic pyrethroids, icon and deltamethrin. There was a significant reduction of malaria incidence following one round of spraying, down to 8.3 cases per 1,000 per month through the rainy season from 13 cases per month in the corresponding season the previous two years.
Abstract: Malaria is endemic in the whole of Zambia and is the leading cause of morbidity and mortality. Prior to 1980, effective malaria control was achieved in the northern mining towns of Chingola and Chililabombwe by means of annual residual spraying programmes. In the 1970s, incidence rates were as low as 20/1000 p.a., but by 2000 had increased to 68/1000 p.a. in Chingola and to 158/1000 p.a.in Chililabombwe. Konkola Copper Mines (KCM) initiated a malaria control programme in which all dwellings in the two towns and within a 10-km radius were sprayed with either dichlorodiphenyltrichloroethane or a synthetic pyrethroid (Icon by ZENECA or Deltamethrin by Aventis). Houses were sprayed in November and December 2000, at the start of the peak transmission period. There was a statistically significant reduction in malaria incidence recorded at KCM health facilities in the two towns, representing a protective incidence rate ratio of 0.65 (95% CI 0.44, 0.97) when comparing the post-spraying period with the corresponding period of the previous 2 years. This reduction followed a single round of house spraying during a year with higher rainfall than the preceding two and in an area where chloroquine was first-line treatment. This house-spraying programme is an example of private/public sector collaboration in malaria control. (Malaria Lead Programme, Medical Research Council, Congella, South Africa)
3) Guyatt, H.L.; S.A. Ochola, and R.W. Snow. Too poor to pay: Charging for insecticide-treated bednets in highland Kenya. Tropical Medicine and International Health: v 7, no 10, pp 846-850. October 2002.
PANNA summary: The authors conducted surveys in areas of rural highland Kenya where Medical Emergency Relief International (MERLIN) initiated the provision of insecticide treated bed nets in 1999. Survey respondents included homes with nets provided by the MERLIN program and those without. They were asked how much they would pay for a bed net and if they didn't have one, why not. The results showed that while the vast majority of households are willing to pay for a bed net, most can not afford to pay the full cost or even a subsidized price. The authors conclude that bed nets should be provided free of charge during WHO's initiative to increase bed nets in homes in order to eliminate the bias toward wealthier families.
Abstract: WHO has proposed malaria control as a means to alleviate poverty. One of its targets includes a 30-fold increase in insecticide-treated nets (ITNs) in the next 5 years. How this service will be financed remains unclear. In July 2000, 390 homesteads in rural highland Kenya were interviewed on their willingness to pay for ITNs. The costs to a household of protecting themselves with ITNs were compared with current household expenditure. Homesteads expressed a willingness to pay for ITNs, but the amounts offered were not sufficient to cover the costs of providing this service without donor support to meet the difference. Furthermore, as most household expenditure was allocated to basic needs these interventions were 'unaffordable'. The cost of protecting a household with ITNs would be equivalent to sending three children to primary school for a year. The aspiration by poor rural homesteads to protect themselves with ITNs is not compatible with their ability to pay. One option to have an immediate equitable impact on ITN coverage and break the cycle between malaria and poverty is to provide this service free of charge. (Wellcome Trust Research Laboratories/KEMRI, Nairobi, Kenya, hguyatt@wtnairobi.mimcom.net)
4) Carnevale, P.; F. Chandre; F. Darriet; D. Fontenille; P. Guillet; J.M. Hougard. Combating malaria vectors in Africa : Current directions of research. Trends in Parasitology. July 2002. Vol.18 No.7.
PANNA summary: The authors propose three interrelated research strategies to support malaria prevention: vector genetics, insecticide resistance and vector control. The strategies are discussed in regard to existing and needed research in these three areas.
Abstract: Vector control remains an important component of malaria control, particularly in Africa where most infant deaths occur. Among the different methods, insecticide treated bed nets seem to be a suitable way to reduce morbidity and child mortality in endemic areas. To facilitate their large-scale use and to investigate alternative vector control methods, the authors propose three current directions of research that are already being explored in Africa through a collaborating network involving several African countries:(1) vector genetics, (2) insecticide resistance and (3) vector control strategies.
5) Utzinger, J., Y. Tozan, F. Doumani, and B.H. Singer. The economic payoffs of integrated malaria control in the Zambian copperbelt between 1930 and 1950. Tropical Medicine and International Health. August 2002, vol. 7. no. 8, pp.657-677.
PANNA summary: In this analysis of the economic benefits of integrated malaria control efforts in copper-mining communities of Zambia between 1930 and 1950, the authors show that integrated methods can be highly effective. As DDT and other chemical insecticides were not in use yet at the time, control strategies included environmental management, improvement in living conditions, improvement of hospital facilities, use of bed nets, and improved availability of anti-malarial drugs. The number of lives, malaria attacks, work shift losses, disability adjusted life years, direct treatment costs, and lost work hours saved more than made up for the cost of implementing the program because of the dramatic increase in copper production and revenues in the area.
Abstract: It has long been suggested that malaria is delaying the economic development of countries that are most severely affected by the disease. Several studies have documented the economic consequences of malaria at the household level, primarily in communities engaged in subsistence farming. A missing element is the appraisal of the economic impact of malaria on the industrial and service sectors that will probably become the backbone of many developing economies. We estimate the economic effects of integrated malaria control implemented during the colonial period and sustained for 20 years in four copper mining communities of the former Northern Rhodesia (now Zambia). Integrated malaria control was characterized by strong emphasis on environmental management, while part of the mining communities also benefited from rapid diagnosis and treatment and the use of bednets. The programmes were highly successful as an estimated 14,122 deaths, 517,284 malaria attacks and 942,347 work shift losses were averted. Overall, 127,226 disability adjusted life years (DALYs) were averted per 3-year incremental period. The cumulative costs of malaria control interventions were US$ 11,169,472 (in 1995 US$). Because the control programmes were so effective, the mining companies attracted a large reservoir of migrant labourers and sustained healthy work forces. The programmes averted an estimated US$ 796,622 in direct treatment costs and US$ 5,678,745 in indirect costs as a result of reduced work absenteeism. Within a few years of programme initiation, Northern Rhodesia became the leading copper producer in Africa, and mining generated the dominant share of national income. Copper production and revenues, which increased dramatically during malaria control interventions, amounted to the equivalent of US$ 7.1 billion (in 1995 US$). Integrated malaria control in copper mining communities was a sound investment. It had payoff for public and occupational health, generally, and without it copper extraction and social and economic development would have been impossible. (Office of Population Research, Princeton University, Princeton, NJ, USA, Woodrow Wilson School of Public and International Affairs, Princeton University, Princeton, NJ, USA, World Bank, Washington, DC, USA)
6) Killeen, Gerry F., U. Fillinger, and B. G. J. Knols. Advantages of larval control for African malaria vectors: Low mobility and behavioral responsiveness of immature mosquito stages allow high effective coverage. Malaria Journal June 21, 2002, 1:8.
PANNA summary: This study starts with the hypothesis that targeting adult mosquitoes with strategies like pyrethrin-treated bed nets and indoor residual spraying is less effective because adult mosquitoes avoid those kinds of obstacles. In the egg and larval stages of development, mosquitoes are confined to a marine habitat and are much less mobile, so absolute coverage is more viable. The authors encourage African nations where malaria is endemic to make larval control a high priority, since the mosquito species that cause most malaria in Africa breed near human settlements and so should be easy to find and control in the larval stages.
Abstract:
BACKGROUND: Based on sensitivity analysis of the MacDonald-Ross model, it has long been argued that the best way to reduce malaria transmission is to target adult female mosquitoes with insecticides that can reduce the longevity and human-feeding frequency of vectors. However, these analyses have ignored a fundamental biological difference between mosquito adults and the immature stages that precede them: adults are highly mobile flying insects that can readily detect and avoid many intervention measures whereas mosquito eggs, larvae and pupae are confined within relatively small aquatic habitats and cannot readily escape control measures.
PRESENTATION OF THE HYPOTHESIS: We hypothesize that the control of adult but not immature mosquitoes is compromised by their ability to avoid interventions such as excito-repellant insecticides.
TESTING THE HYPOTHESIS: We apply a simple model of intervention avoidance by mosquitoes and demonstrate that this can substantially reduce effective coverage, in terms of the proportion of the vector population that is covered, and overall impact on malaria transmission. We review historical evidence that larval control of African malaria vectors can be effective and conclude that the only limitations to the effective coverage of larval control are practical rather than fundamental.
IMPLICATIONS OF THE HYPOTHESIS: Larval control strategies against the vectors of malaria in sub-Saharan Africa could be highly effective, complementary to adult control interventions, and should be prioritized for further development, evaluation and implementation as an integral part of Rolling Back Malaria. (Department of Tropical Medicine, School of Public Health and Tropical Medicine,Tulane University Health Sciences Centre, 1430 Tulane Avenue, New Orleans, Louisiana 70112, USA, gerrykilleen@hotmail.com)
7) Guyatt, H.L., J. Kinnear, M. Buruni, and R.W. Snow. A comparative cost analysis of insecticide-treated nets and indoor residual spraying in highland Kenya. Health Policy and Planning 2002; 17(2): 144-153.
PANNA summary: Indoor residual spraying is more cost-effective than insecticide-treated nets in the highlands of Kenya. This conclusion was reached through a cost analysis for both methods, in terms of cash expenditures and also in broader economic terms including the opportunity costs of using staff for these purposes and capital costs.
Abstract: The relative cost of indoor residual house-spraying (IRS) versus insecticide-treated bednets (ITNs) forms part of decisions regarding selective malaria prevention. This paper presents a cost comparison of these two approaches as recently implemented by Merlin, a UK emergency relief organization funded through international donor support and working in the highland districts of Gucha and Kisii in Kenya. The financial costs (cash expenditures) and the economic costs (including the opportunity costs of using existing staff and volunteers, and an annualized cost for capital items) were assessed. The financial cost for IRS was US$0.86 per person protected, compared with $4.21 for ITNs (reducing to $3.42 to the provider assuming cost recovery). The economic cost per person protected for IRS was $0.88, compared with $2.34 for ITNs. The costs for ITNs were sensitive to the number of nets sold per community group ('efficiency'), as the delivery costs constituted upwards of 40% of the total cost. However, even marked increases in efficiency of these groups could not reduce the costs of ITNs to that comparable with IRS, except if more than one cycle of IRS was needed. The implications of predicted reductions in the cost of insecticide for both IRS and ITNs are also explored. The provision of itemized cost data allows predictions to be made on changes in the design of these programmes. Under almost all design scenarios, IRS would appear to be a more cost-efficient means of vector control in the Kenyan highlands. (Kenya Medical Research Institute/Wellcome Trust Collaborative Programme, Nairobi, Kenya, Centre for Tropical Medicine, University of Oxford, Oxford, UK, Hguyatt@wtnairobi.mimcom.net)
8) Guyatt, H.L., S.K. Corlet, T.P. Robinson, S.A. Ochola, and R.W. Snow. Malaria prevention in highland Kenya: Indoor residual house-spraying vs. insecticide-treated bednets. Tropical Medicine and International Health. April 2002. vol. 7 no. 4: pp. 298-303.
PANNA summary: This study finds that indoor residual spraying (IRS) is both more effective and less expensive than insecticide-treated bed nets (ITN) for controlling malaria in the highlands of Kenya. In blood tests of the residents of homes where IRS and ITN were used after a malaria outbreak, it was found that IRS-treated homes had a lower percentage of residents with malaria parasites still in their blood than ITN-treated homes, and that the cost had also been significantly lower.
Abstract: This study compares the effectiveness and cost-effectiveness of indoor residual house-spraying (IRS) and insecticide-treated bednets (ITNs) against infection with Plasmodium falciparum as part of malaria control in the highlands of western Kenya. Homesteads operationally targeted for IRS and ITNs during a district-based emergency response undertaken by an international relief agency were selected at random for evaluation. Five hundred and ninety homesteads were selected (200 with no vector control, 200 with IRS and 190 with ITNs). In July 2000, residents in these homesteads were randomly sampled according to three age-groups: 6 months-4 years, 5-15 years, and > 15 years for the presence of P. falciparum antigen (Pf HRP-2) using the rapid whole blood immunochromatographic test (ICT). The prevalence of P. falciparum infection amongst household members not protected by either IRS or ITN was 13%. Sleeping under a treated bednet reduced the risk of infection by 63% (58-68%) and sleeping in a room sprayed with insecticide reduced the risk by 75% (73-76%). The economic cost per infection case prevented by IRS was US$ 9 compared to US$ 29 for ITNs. This study suggests that IRS may be both more effective and cheaper than ITNs in communities subjected to low, seasonal risks of infection and as such should be considered as part of the control armamentarium for malaria prevention. (Wellcome Trust Research Laboratories/KEMRI, Nairobi, Kenya, hjuyatt@wtnairobi.mimcom.net)
9) Romi, R., M.C. Razaiarimanga, R. Raharimanga, E.M. Rakotondraibe, L.H. Ranaivo, V. Pietra, A. Raveloson, and G. Majori. Impact of the Malaria Control Campaign (1993-1998) in the highlands of Madagascar: Parasitological and entomological data. American Journal of Tropical Medicine and Hygiene. 66(1), 2002, pp. 2-6.
PANNA summary: The study tracks malaria prevalence in the highlands of Madagascar through five years of an Italian-run and World Bank funded control program (1993-1998), a response to the reappearance of epidemic malaria in the region in the late 1980s. The program used annual indoor spraying of DDT and improved availability of chloroquine, and appears to have been effective, with significant decreases in the number of malaria cases and the abundance of the main vector species in villages throughout the region.
Abstract: Malaria transmission in the central highlands of Madagascar was interrupted in the 1960s by a national control program that used DDT indoor spraying and mass treatment with chloroquine. At the end of the 1980s in this region, epidemic malaria reappeared. Italian health authorities provided technical assistance to the National Malaria Control Program since the beginning of the resurgence of malaria in the central highlands. Yearly residual house spraying performed for 5 years (1993-1998) and the availability of antimalarial drugs reduced malaria transmission to very low levels, with improvement in parasitologic and entomologic indexes. A significant reduction of malaria prevalence was observed in the villages located at altitudes of 1,000-1,500 m, corresponding to the stratum of unstable malaria that was the main target of the antivector interventions. A significant reduction of malaria prevalence was also observed in the villages located at altitudes of 900-1,000 m, where malaria transmission is stable. The main vector Anopheles funestus was dramatically reduced in abundance and distribution in the sprayed areas. (Laboratorio di Parassitologia, Istituto Superiore di Sanita, Roma, Italy. romi@iss.it)
10) Mnzava, A.E.P., B.L. Sharp, D.J. Mthembu, D. le Sueur, S.S. Dlamini, J.K. Gumede, and I. Kleinschmidt. Malaria control: Two years' use of insecticide-treated bednets compared with insecticide house spraying in KwaZulu-Natal. South African Medical Journal, November 2001. Vol. 91, No. 11, pp. 978-983.
PANNA summary: This study found that use of insecticide-treated bed nets was more effective for preventing malaria than indoor spraying of the insecticide deltamethrin over the course of two years (1997-'99) in KwaZulu-Natal. However, they warn that cost-effectiveness has varied in studies in different countries around the world, and so encourage the South African Department of Health to consider more data on cost and long-term effectiveness of treated bed nets.
Abstract:
OBJECTIVES: The objective of this study was to produce data indicating whether insecticide-treated bednets should replace insecticide house spraying as a malaria control method in South Africa. We report 2 years of preliminary data on malaria incidence comparing areas receiving insecticide-treated bednets and those subjected to house spraying in northern KwaZulu-Natal.
DESIGN, SETTING AND SUBJECTS: In order to measure significant reductions in malaria incidence between the two interventions, a geographical information system (GIS) was used to identify and create seven pairs of geographical blocks (areas) in the malaria high-risk areas of Ndumu and Makanis in Ingwavuma magisterial district, KwaZulu-Natal. Individual blocks were then randomly allocated to either insecticide-treated bednets or house spraying with deltamethrin. Malaria cases were either routinely recorded by surveillance agents at home or were reported to the nearest health facility.
RESULTS AND CONCLUSIONS: The results show that 2 years' use of insecticide-treated bednets by communities in Ndumu and Makanis, KwaZulu-Natal, significantly reduced the malaria incidence both in 1997 (rate ratio (RR) = 0.879, 95% confidence interval (CI) 0.80-0.95, P = 0.04) and in 1998 (RR = 0.667, CI 0.61-0.72, P = 0.0001). Using a t-test, these significant reductions were further confirmed by an assessment of the rate of change between 1996 and 1998, showing a 16% reduction in malaria incidence in blocks using treated bednets and an increase of 45% in sprayed areas (t = 2.534, P = 0.026 (12 df)). In order to decide whether bednets should replace house spraying in South Africa, we need more data on the efficacy of treated bednets, their long-term acceptability and the cost of the two interventions. (Malaria Research Lead Programme, South African Medical Research Council, Durban)
11) Jambou R., Ranaivo L., Raharimalala L., Randrianaivo J., Rakotomanana F., Modiano D., Pietra V., Boisier P., Rabarijaona L., Rabe T., Raveloson N., De Giorgi F. Malaria in the highlands of Madagascar after five years of indoor house spraying of DDT. Transactions of the Royal Society of Tropical Medicine and Hygiene (2001) 95, 14-18.
PANNA summary: This article reports on a study of the prevalence of malaria parasites in the blood of school children in the highlands of Madagascar, in regions where DDT spraying campaigns to eliminate the vector Anopheles funestus were carried out between December 1993 and January 1998. Parasite prevalence in children was generally found to decline with increasing altitude, but below 1,500 meters, the impact of the spraying campaigns was clear. Below 1,000 meters, parasite prevalence was 2.7% in villages that had been sprayed and 20% in those that hadn’t; between 1,000 and 1,500 meters, the difference was .8% to 4.5%. However, the presence of antibodies to the parasite was much more common than the parasite itself, appearing in 22-63% of children in each school, indicating that the parasite is still in active circulation. The authors warn against the high potential for rapid re-infection of the area from lower neighboring areas and suggest bolstering current surveillance efforts with continued spraying of DDT in the marginal zones.
Abstract: The central region of Madagascar is a vast area of highlands (altitude 700-2000 m). Malaria transmission has re-established itself here since the last epidemic of 1985-90 and has caused the deaths of 40,000 persons according to the Minister of Health. To combat the main malaria vector in the region, Anopheles funestus, annual programmes of indoor house spraying of DDT were carried out between December 1993 and January 1998 in most rural areas at altitude 1000-1500 m. A parasitological and serological study was then conducted in the highland schools to evaluate the impact of the programme and set up a database on the region. Using a cluster-sampling method 2 independent selections were conducted (one of 130 sites, the other of 40 sites). During the study, 13,462 schoolchildren were examined, 71% living in sprayed villages. Parasite prevalence among schoolchildren declined as altitude increases, from 11% at 700-900 m to 0.4% at > 1500 m. Below 1500 m, the impact of the spraying on the prevalence of the parasite was very clear (an average decrease of from 20% to 2.7% below 1000 m and of from 4.5% without spraying to 0.8% at 1000-1500 m). Geographical analysis of the data showed that the marginal regions remained the most affected by malaria (especially outside spraying zones), and persistence of 'pockets of transmission' at 1000-1500 m, essentially in areas where spraying has never been used. In 9 schools, anti-Plasmodium antibodies were sought by indirect immunofluorescence on thick smears of parasitized red blood cells. The seroprevalence ranged from 22% to 63%, which suggests that the parasite is still circulating in the region. Even though our data show that vector control continues to be very successful in the Madagascan highlands, rapid reinfection could occur and must be monitored following spraying. To this end, the Minister for Health, with the support of the Italian Co-operation, has placed the region under epidemiological surveillance since 1997. An alert system for the timely detection of the sources of epidemics and the targeting of the antivectoral campaign is also in operation. Our study suggests that this strategy should be reinforced by the spraying of DDT in the marginal zones in order to consolidate the results obtained at higher altitudes. (Pasteur Institute of Madagascar, Madagascar. rjambou@pasteur.sn)
12) Schellenberg, D., C. Menendez, E. Kahigwa, J. Aponte, J. Vidal, M. Tanner, H. Mshinda, P. Alonso. Intermittent treatment for malaria and anemia control at time of routine vaccinations in Tanzanian infants: A randomized, placebo-controlled trial. Lancet 2001; 357: 1471-77.
PANNA summary: In this study of seven hundred infants in Ifakara, Tanzania, children were given weight-appropriate doses of the anti-malarial and anti-anemia drug sulphadoxine-pyrimethamine (or a placebo pill) at the time of immunization by WHO's Expanded Program on Immunization: two, three, and nine months old. Incidence of malaria in the first year of life was 59% less in the group who received the medication than in the group who received the placebo, and incidence of anemia was 50% less, even though both groups received iron supplements. This method of malaria control shows potential for delaying first malaria incidence in young children to a time when their immune systems are better equipped to deal with the disease.
Abstract:
BACKGROUND: Clinical malaria and severe anaemia are major causes of paediatric hospital admission and death in many malaria-endemic settings. In the absence of an effective and affordable vaccine, control programmes continue to rely on case management while attempting the large-scale deployment of insecticide-treated nets. We did a randomised, placebo-controlled trial to assess the efficacy and safety of intermittent sulphadoxine-pyrimethamine treatment on the rate of malaria and severe anaemia in infants in a rural area of Tanzania.
METHODS: We randomly assigned 701 children living in Ifakara, southern Tanzania, sulphadoxine-pyrimethamine or placebo at 2, 3, and 9 months of age. All children received iron supplementation between 2 and 6 months of age. The intervention was given alongside routine vaccinations delivered through WHO's Expanded Program on Immunisation (EPI). The primary outcome measures were first or only episode of clinical malaria, and severe anaemia in the period from recruitment to 1 year of age. Morbidity monitoring through a hospital-based passive case-detection system was complemented by cross-sectional surveys at 12 and 18 months of age. Results were expressed in terms of protective efficacy (100 [1-hazard ratio]%) and analysis was by intention to treat.
FINDINGS: 40 children dropped out (16 died, 11 migrated, 12 parents withdrew consent, and one for other reasons). Intermittent sulphadoxine-pyrimethamine treatment was well tolerated and no drug-attributable adverse events were recorded. During the first year of life, the rate of clinical malaria (events per person-year at risk) was 0.15 in the sulphadoxine-pyrimethamine group versus 0.36 in the placebo group (protective efficacy 59% [95% CI 41-72]), and the rate of severe anaemia was 0.06 in the sulphadoxine-pyrimethamine group versus 0.11 in the placebo group (50% [8-73]). Serological responses to EPI vaccines were not affected by the intervention.
INTERPRETATION: This new approach to malaria control reduced the rate of clinical malaria and severe anaemia by delivering an available and affordable drug through the existing EPI system. Data are urgently needed to assess the potential cost-effectiveness of intermittent treatment in areas with different patterns of malaria endemicity. (Unidad de Epidemiologia, Hospital Clinic, Institut d'Investigacions Biomediques August Pi i Sunyer (IDIBAPS), Villarroel 170, 08036, Barcelona, Spain)
13) Curtis, C.F., A.E.P. Mnzava. Comparison of house spraying and insecticide-treated nets for malaria control. Bulletin of the World Health Organization, 2000, 78(12): pp 1389-1400.
PANNA summary: This study of data from Africa, Asia, and Melanesia on the effectiveness of insecticide-treated bed nets compared with residual indoor spraying found that while the nets were as effective as indoor spraying in recent studies, they did not come close to the effectiveness once achieved by indoor spraying of DDT during the malaria eradication campaigns of 30+ years ago. This may be due in part to the longer duration of the early spraying projects, and to the fact that the pyrethroids most often used on the bed nets are excito-repellants, causing mosquitoes to leave, rather than non-irritants like DDT, which more often kill the mosquitoes. As bed nets are much smaller than the walls of a house and so much cheaper to retreat with insecticide, they may prove to be less expensive than spraying campaigns.
Abstract: The efficacies of using residual house spraying and insecticide-treated nets against malaria vectors are compared, using data from six recent comparisons in Africa, Asia and Melanesia. By all the entomological and malariological criteria recorded, pyrethroid-treated nets were at least as efficacious as house spraying with dichlorodiphenyltrichloroethane (DDT), malathion or a pyrethroid. However, when data from carefully monitored house spraying projects carried out between the 1950s and 1970s at Pare-Taveta and Zanzibar (United Republic of Tanzania), Kisumu (Kenya) and Garki (Nigeria) are compared with recent insecticide-treated net trials with apparently similar vector populations, the results with the insecticide-treated nets were much less impressive. Possible explanations include the longer duration of most of the earlier spraying projects and the use of non-irritant insecticides. Non-irritant insecticides may yield higher mosquito mortalities than pyrethroids, which tend to make insects leave the site of treatment (i.e. are excito-repellent). Comparative tests with non-irritant insecticides, including their use on nets, are advocated. The relative costs and sustainability of spraying and of insecticide-treated net operations are briefly reviewed for villages in endemic and epidemic situations and in camps for displaced populations. The importance of high population coverage is emphasized, and the advantages of providing treatment free of charge, rather than charging individuals, are pointed out. (London School of Hygiene and Tropical Medicine, London WC1E 7HT, England. chris.curtis@lshtm.ac.uk)
14) Cox, J.S.H., J. Mouchet, and D.J. Bradley. Determinants of malaria in Africa. In Contextual Determinants of Malaria, and also presented at an International Workshop, Lausanne, Switzerland, May 14-18, 2000.
PANNA summary: Malaria is more endemic in Sub-Saharan Africa than anywhere else in the world. There is nonetheless some variation that can be helpful to understand for predicting outbreaks. In some areas, the spread of malaria varies because of factors like rainfall, altitude, and latitude. This malaria is unstable and highly susceptible to small environmental variation. In other areas, malaria is highly endemic and stable and so the effects of environmental and social changes are less pronounced.
(no abstract available)
15) Bouwman, Henk. Malaria control and the paradox of DDT. Africa--Environment and Wildlife. vol. 8, no. 4, May 2000. http://www.icps.it/english/bollettino/psn00/000303.htm
PANNA summary: A balanced look at the helpful-harmful paradox of DDT use against malaria in Africa. The author's pointers for future use of insecticides against malaria are especially interesting, as they include environmental monitoring and investigation of alternatives to spraying in houses where women's and children's exposure can be greatest.
(no abstract available)
16) Bosman, A, Y Kassankogno, and AV Kondrachine. Implementation of malaria control. Parassitologia 41: 391-3, 1999.
PANNA summary: The deterioration of the malaria situation around the world and especially in Sub-Saharan Africa is being met with control strategies deficient in forecasting, early detection, and containment of malaria epidemics, and research and control communities that are too widely separated from one another. In order to tackle this problem and ease the economic burden of malaria on the world's poorest people, energies should be focused on guiding the money that is already being spent on malaria control in these communities into the most cost-effective medicines and vector control strategies.
Abstract: Global trends of infant and child mortality have decreased over the last 30 years, while the proportion of malaria deaths has progressively increased due to the deteriorating situation in sub-Saharan Africa. The Global Malaria Control Strategy promoted by WHO has encountered several obstacles to its implementation. Early diagnosis and prompt treatment can reduce malaria mortality, but there is still low investment on safe and effective modalities of care delivery at the periphery, where most of the malaria burden exists. Selective vector control (indoor residual spraying and insecticide-treated nets) plays a significant role outside Africa, but its wider use is limited by cost/affordability problems and operational issues (supply, delivery and logistics). Alternative methods such as environmental management and biological control are cost-effective only under very specific epidemiological situations. In most countries forecasting, early detection and containment of malaria epidemics is deficient, and there is separation between the research and control communities, particularly in Africa. Involvement of the internal agencies, strategic investments in capacity building and institutional networking are needed to strengthen capacity for malaria and research in the countries. The major responsibility is to guide the expenditure made by the communities (which far out-weigh the limited share of national health budgets) towards the most cost-effective approaches to reduce malaria mortality and morbidity. (Communicable Diseases Prevention and Control, World Health Organisation, Geneva, Switzerland. bosmana@who.ch)
17) Salako, LA. Malaria control priorities and constraints. Parassitologia 41: 495-6, 1999.
PANNA summary: The author argues that the top priority in malaria control should be changing attitudes of malaria control workers. Many cling to the idea that people already know all there is to know about malaria, when the reality is that certain habits persist that foster malaria transmission. Constraints include health budgets, inequities in the distribution of funds, lack of human resources, and unavailability of effective drugs.
Abstract: The capacity to prioritize correctly actions in malaria control depends on good knowledge not only of the epidemiology of the disease in the area but also of the behaviour of the people. Health policy makers frequently believe that the people already know enough about malaria and there is no need to commit further resources on finding out what the people actually know and do about the disease in order to modify their wrong habits. One of the pressing priorities for malaria control in Africa is therefore changing the attitude of malaria control policy makers. Considering the constraints to malaria control it is stressed that the health budget is usually below a level sufficient to finance an effective health care system. This is further compounded by inequities in the allocation of funds between health care institutions located in the urban areas compared with those located in the rural areas. Another important constraint is lack of manpower suitably trained to undertake the various elements of the global malaria control strategy. Finally, a very well known constraint is the unavailability of effective drugs at the locations where they are needed. (Nigerian Institute of Medical Research, Yaba, Lagos, Nigeria. nimr@scd.metrong.com)
18) Fontenille, D and L Lochouarn. The complexity of the malaria vectorial system in Africa. Parassitologia 41: 267-271, 1999.
PANNA summary: There are as many as five different mosquito species that transmit malaria in Africa; sometimes more than one species will transmit the disease in one place at one time, and sometimes different species will transmit the disease in the same place, but at different times of year. The authors stress that vector control strategies should take the diversity of the vectors into account and plan accordingly, as the control of one or two of the vector species will not be as effective as the control of all five.
Abstract: The malaria vectorial system in Africa is very complex. Five very efficient vector species transmit malaria: Anopheles gambiae, An. arabiensis, An. funestus, and the sometimes overlooked An. nili and An. moucheti. This paper focuses on morphological, behavioural and genetic differences observed among populations within each vector species. It emphasizes that future strategies for controlling vectors should take into account this heterogeneity.
19) Teklehaimanot, A, and A Bosman. Opportunities, problems and perspectives for malaria control in sub-Saharan Africa. Parassitologia 41: 335-8, 1999.
PANNA summary: This article focuses on the malaria problem in sub-Saharan Africa: the factors that have contributed to it over the years, current efforts to control malaria, and warnings for the future of those efforts. Malaria has persisted in the region because of environmental conditions conducive to the spread of malaria and widespread poverty. While the current growth of new programs with an interest in controlling malaria is heartening, the author warns that when control efforts have been interrupted in the past, resilient malaria has always come back with devastating consequences. Effective malaria control in sub-Saharan Africa can only come in the form of long-term, sustained action that is firmly rooted in the social development of the country.
Abstract: Environments conducive to high malaria transmission and widespread poverty are at the roots of the 'malaria giant', which affects 46 countries in Africa. The recent interest in and momentum of work on malaria, in endemic countries and the international community, is unprecedented and opens new perspectives for controlling the disease. Significant steps included: (i) the allocation of US$20 million by WHO for accelerated implementation of malaria control in 34 African countries in 1997-98; (ii) the Declaration on Malaria by the Heads of States of the Organization of African Unity and the establishment of the African Initiative for Malaria Control in 1997; (iii) the concomitant mobilisation of the research community in the Multilateral Initiative on Malaria; (iv) the G8 Summit in 1998 in Birmingham asking for higher commitment to malaria control, particularly in Africa; and (v) the Roll Back Malaria initiative set as a WHO priority project in 1998. However, experiences have proved the alarming 'resilience' of the malaria system in Africa, showing devastating consequences when malaria returns to the original levels after intensive control is interrupted. Effective malaria control in Africa requires long-term action, firmly rooted in the social development of the country. (World Health Organization, Communicable Diseases Prevention and Control, Geneva, Switzerland)
20) Toure, YT. The malaria challenge in the 21st century: Perspectives for Africa. Parassitologia 41: 507-9. 1999.
PANNA summary: The author pinpoints the main causes for the failure of malaria control campaigns in Africa in the past: resistance to drugs on the part of the parasites and to insecticides on the part of the vectors, inadequate health infrastructure, and lack of trained health professionals and scientists. The main goals for the 21st century are the same as they have always been, to reduce morbidity and mortality due to malaria, and to reduce malaria transmission. The problem is not necessarily in the research, but in the implementation—the best strategies are often underutilized and applied inefficiently. It has become clear that malaria is irrevocably connected to rural poverty, and the author makes the powerful statement that: “Provision of basic health care centers, schools, and safe water supplies to the rural areas may contribute much more to malaria (…) control than most of the activities which have been undertaken up to the present time.”
Abstract: Malaria control has had little success in Africa despite the achievements in malaria research. It is time to put more emphasis on sustainable control measures through local commitment to diagnose and treat malaria in order to prevent illness and death. This goal can be best achieved through basic health care centers, schools and safe water supplies to rural areas. Complementary actions through research and international support will be strongly needed. (Departement d'Epidemiologie des Affections Parasitaires, Ecole Nationale de Medecine, de Pharmacie et d'Odonto-Stomatologie, Bamako, Mali. yeya@mrtcbko.malinet.ml)
21) Greenwood, B. Malaria mortality and morbidity in Africa. Bulletin of the World Health Organization.1999, 77(8), 617-8.
PANNA summary: The author argues that though it is difficult to obtain accurate information on malaria mortality and morbidity in Africa, this information is crucially important for the national Ministries of Health, who must prioritize their spending and need to know how big a threat the various diseases of the region really are. Malaria is only one of the major killers of African children--in various regions, diseases like measles and pneumonia can claim as many lives as malaria. What's more, the symptoms of some of these diseases appear similar to those of malaria, and in such poor areas many of the cases are never admitted to hospitals for treatment, so accurate data is hard to come by.
(editorial, no abstract available)
22) Goodman, C.A., P.G. Coleman, and A.J. Mills. Cost-effectiveness of malaria control in sub-Saharan Africa. The Lancet 354: July 31, 1999, 378-85.
PANNA summary: In an attempt to inform WHO's Roll Back Malaria campaign, the authors used mathematical models to calculate the costs of various malaria control strategies in a very low income sub-Saharan African country, like residual insecticide spraying and the use of insecticide-treated bed nets, drugs like chloroquine given during pregnancy and during early childhood, and making improvements upon current malaria treatments. The costs were calculated per disability-adjusted life year, and ranged from $4-10. While this is relatively affordable when compared with health interventions aimed at other health problems, the authors point out that governments of the poorest nations will not be able to supply this money to their most impoverished populations without help from the international community.
Abstract: Antimalarial chemoprophylaxis during pregnancy significantly increases the birth weight of babies born to primigravidae, but coverage in sub-Saharan Africa is very limited. This analysis assessed whether increasing coverage is justified on cost-effectiveness grounds. A standardized modeling framework was used to estimate ranges for the cost per discounted year of life lost averted by weekly chloroquine chemoprophylaxis and intermittent sulfadoxine-pyrimethamine (SP) treatment for primigravidae in an operational setting with moderate to high malaria transmission. The SP regimen was found to be more cost-effective than the chloroquine regimen, because of both lower costs and higher compliance. Both regimens appear to be a good value for money in comparison with other methods of malaria control and based on rough cost-effectiveness guidelines for low-income countries, even with high levels of drug resistance. However, extending the SP regimen to all gravidae and increasing the number of doses per pregnancy could make the intervention significantly less cost-effective. (Department of Public Health and Policy, London School of Hygiene and Tropical Medicine, United Kingdom. catherine.goodman@lshtm.ac.uk)
23) Coetzee, M., D.W.K. Horne, B.D. Brooke, and R.H. Hunt. DDT, dieldrin, and pyrethroid insecticide resistance in African malaria vector mosquitoes: An historical review and implications for future malaria control in southern Africa. South African Journal of Science 95, May 1999, p 215-8.
PANNA summary: This paper reviews articles on vector resistance to the insecticides DDT, dieldrin, and pyrethroids, mapping them out over the history of their use and over Southern Africa. As control programs have been moving away from DDT and dieldrin and toward pyrethroids and other alternative insecticides in more recent years, resistances to pyrethroids have also been developing among vector populations.
Abstract: Historical records of dieldrin and DDT insecticide resistance in the African malaria vectors Anopheles gambiae and An. arabiensis have been mapped. Policy changes to the malaria control programmes in South Africa have resulted in DDT being phased out as the insecticide of choice and replaced with pyrethroids. Recent records of resistance to pyrethroids in An. gambiae in West Africa raise concern about the future usefulness of pyrethroids for malaria control in southern Africa.
24) Lindsay, S.W., and W.J.M. Martens. Malaria in the African highlands: Past, present, and future. Bulletin of the World Health Organization. 1998, 76, pp. 33-45.
PANNA summary: There has been a steady rise in malaria in the African highlands over the past fifty years due to environmental changes and deteriorating health care. The highlands were once considered a safe haven from diseases that have always been widespread in the plains, but no longer. Because highland populations don’t have the natural resistance to malaria that plains people have developed over generations, epidemics in these regions can hit particularly hard. This study maps out the most epidemic-prone regions and projects their spread with global warming. The author recommends that special attention be paid to preventing malaria epidemics in the highland regions.
Abstract: Many of the first European settlers in Africa sought refuge from the heat and diseases of the plains by moving to the cool and salubrious highlands. Although many of the highlands were originally malaria free, there has been a progressive rise in the incidence of the disease over the last 50 years, largely as a consequence of agroforestry development, and it has been exacerbated by scarce health resources. In these areas of fringe transmission where the malaria pattern is unstable, epidemics may be precipitated by relatively subtle climatic changes. Since there is little immunity against the disease in these communities, outbreaks can be devastating, resulting in a substantial increase in morbidity and death among both children and adults. We present here the results obtained using a mathematical model designed to identify these epidemic-prone regions in the African highlands and the differences expected to occur as a result of projected global climate change. These highlands should be recognized as an area of special concern. We further recommend that a regional modeling approach should be adopted to assess the extent and severity of this problem and help improve disease surveillance and the quality of health care delivered in this unstable ecosystem. (Department of Biological Sciences, University of Durham, England)
25) Curtis, C.F., C.A. Maxwell, R.J. Finch, and K.J. Njunwa. A comparison of use of a pyrethroid either for house spraying or for bednet treatment against malaria vectors. Tropical Medicine and International Health. 3(8) 619-31, August 1998.
PANNA summary: Using the pyrethroid insecticide lambdacyhalothrin to treat bed nets and using it to spray the inside walls of homes in northeast Tanzania proved to be equally effective at lowering the probability of malaria infection in children by 54-62%. However, treating bed nets used about one sixth the amount of insecticide as indoor spraying, and people in the area were much more enthusiastic about the bed nets, so the researchers conclude that pyrethroid-treated bed nets are more cost-effective than indoor spraying of the same chemicals.
Abstract: In an intensely malarious area in north-east Tanzania, microencapsulated lambdacyhalothrin was used in four villages for treatment of bednets (provided free of charge) and in another four villages the same insecticide was used for house spraying. Another four villages received neither intervention until the end of the trial but were monitored as controls. Bioassays showed prolonged persistence of the insecticidal residues. Light traps and ELISA testing showed reduction of the malaria vector populations and the sporozoite rates, leading to a reduction of about 90% in the entomological inoculation rate as a result of each treatment. Collections of blood fed mosquitoes showed no diversion from biting humans to biting animals. Incidence of re-infection was measured by weekly monitoring of cohorts of 60 children per village, after clearing preexisting infection with chlorproguanil-dapsone. The vector control was associated with a reduction in probability of re-infection per child per week by 54-62%, with no significant difference between the two vector control methods. Cross-sectional surveys for fever, parasitaemia, haemoglobin and weight showed association of high parasitaemia with fever and anaemia and beneficial effects of each intervention in reducing anaemia. However, passive surveillance by resident health assistants showed no evidence for reduced prevalence of fever or parasitaemia. Net treatment consumed only about one sixth as much insecticide as house spraying and it was concluded that the former intervention would work out cheaper and nets were actively demanded by the villagers, whereas spraying was only passively assented to. (London School of Hygiene and Tropical Medicine, UK. c.curtis@lshtm.ac.uk)
26) Greenwood, B.M. Malaria transmission and vector control. Parasitology Today 1997, 13(3), 90-1.
PANNA summary: Arguments have been made that bed nets and other vector control strategies used in highly endemic regions such as Sub-Saharan Africa are only delaying cases of malaria, as they are slowing the population's natural process of developing immune resistance to the disease. Greenwood argues against this hypothesis, citing several studies among children in endemic regions of Africa that show children’s immunity is slower to develop, and their infection rates relate pretty directly to the number of bites received in a day. In this case, the author advocates the continued use of vector control strategies in Africa in the interest of saving children’s lives. Studies have shown that adults do not lose their natural resistance once they’ve developed it, and in a community using pesticide-treated nets the number of bites will still be high enough to ensure that resistance is maintained.
(no abstract available)
27) Bruce-Chatt, L. J. Lessons learned from applied field research activities in Africa during the malaria eradication era. Bulletin of the World Health Organization. 1984. 62 (Suppl.). 19-29.
PANNA summary: The author presents an assessment of the various malaria eradication and prevention methods used in Africa from 1950 to 1974. The author then examines the period from 1975 to 1984, during which research and technological advances helped to reduce the number of cases of malaria.
Abstract: The Malaria Conference in Equatorial Africa, convened by the World Health Organization in 1950 in Kalpala , Uganda , was a milestone in the history of modern malaria control activities on the continent of Africa . It is presented and assessed the available international information on epidemiological aspects of this disease and attempted to coordinate the various methods of research and control of malaria. Its two main recommendations were that malaria should be controlled by all available health methods, irrespective of the degree of endemicity of the disease, and that the benefits that malaria control might bring to the indigenous population should be evaluated.
The first period of field research and pilot control projects in Africa was between 1950 and 1964. A large number of studies in several African countries showed that the use of residual insecticides such as DDT and HCH might decrease, at times considerably, the amount of malaria transmission, but interruption of transmission could not be achieves, except in two relatively small projects in the forest areas of the Cameroon and Liberia. During the second period, from 1965 to 1974, the difficulties of malaria eradication and control in Africa became more evident because of the development of resistance of Anopheles gambiae to DDT, HCH and dieldrin; moreover administrative, logistic, and financial problems had emerged. It became clear that the prospects for malaria control (let alone those for eradication) were related to the availability of a network of basic health services. A number of “pre-eradication” programmes were set up in order to develop better methods of malaria control and to improve the rural health infrastructures. Much field research on the chemotherapy of malaria was carried out and the value of collective or selective administration of antimalarial drugs was fully recognized, although it became obvious that this could not plan an important part in the decrease of transmission of malaria in Africa. The role of research as one of the ways of solving the technical problems of malaria control in tropical Africa was stressed from the early days of the global malaria eradication programs; the past ten years have seen and immense expansion of this activity.