Effectiveness of malaria control during changing climate conditions in Eritrea, 1998–2003

Abstract

Summaryobjective To assess the effectiveness of impregnated mosquito nets, indoor residual spraying and larval control relative to the impacts of climate variability in the decline of malaria cases in Eritrea.methods Monthly data on clinical malaria cases by subzoba (district) in three zobas (zones) of Eritrea for 1998-2003 were used in Poisson regression models to determine whether there is statistical evidence for reduction in cases by DDT, malathion, impregnated nets and larval control used over the period, while analysing the effects of satellite-derived climate variables in the same geographic areas.results Both indoor residual spraying (with DDT or malathion) and impregnated nets were independently and significantly negatively associated with reduction in cases, as was larval control in one zoba. Malaria cases were significantly positively related to differences in current and previous months' vegetation (NDVI) anomalies. The relationship to rainfall differences 2 and 3 months previously was also significant, but the direction of the effect varied by zoba. Standardized regression coefficients indicated a greater effect of climate in the zoba with less intense malaria transmission.conclusion The results support the view that both indoor residual spraying and impregnated nets have been independently effective against malaria, and that larval control was also effective in one area. Thus climate, while significant, is not the only explanation for the recent decline in malaria cases in Eritrea. If appropriate statistical approaches are used, routine surveillance data from cases attending health facilities can be useful for assessing control programme success and providing estimates of the effectiveness of individual control measures. Effectiveness estimates suitable for use in cost-effectiveness analysis have been obtained.

Epidemiology and Infectivity of Plasmodium falciparum and Plasmodium vivax Gametocytes in Relation to Malaria Control and Elimination

“…These global estimates are a direct result of an increasing ability to collate and assimilate large data sets that also allow the monitoring of trends in malaria incidence and parasite prevalence. These broad-scale estimates from countries where malaria is endemic (178), together with specific country examples (23,24,35,87,174,227,328,329), have highlighted the recent trend of decreasing malaria transmission intensity in many areas of endemicity, and these observations, at least in part, have stimulated (or restimulated) the malaria elimination agenda (8b, 276). While there is considerable debate in the malaria community about the rationale and likely success of elimination programs, the ongoing discussions have led to a reevaluation of current strategies to reduce or abrogate the transmission of malaria parasites.…”

Continuing Intense Malaria Transmission in Northern Uganda

“…9 Widespread use of insecticide-treated nets (ITNs), 1-3, 5, 6 effective vector control, 1,3,6 increased urbanization, 10 and treatment of uncomplicated falciparum malaria with artemisinin-based combination therapies (ACT) 1,2,7 have all been assumed to contribute to the reported reductions in malaria incidence, although in some areas these reductions were observed before control measures were scaled up. 8 This widespread decline in the burden of malaria has resulted in optimism that malaria can be eliminated in parts of Africa where malaria is currently endemic.…”

“…Despite reported reductions in malaria transmission intensity in several African regions, [1][2][3][4][5][6][7][8] malaria remains one of the most important public health problems in sub-Saharan Africa with an estimated 863,000 deaths annually. 9 Widespread use of insecticide-treated nets (ITNs), 1-3, 5, 6 effective vector control, 1,3,6 increased urbanization, 10 and treatment of uncomplicated falciparum malaria with artemisinin-based combination therapies (ACT) 1,2,7 have all been assumed to contribute to the reported reductions in malaria incidence, although in some areas these reductions were observed before control measures were scaled up.…”

“…11 However, reports of reductions in malaria transmission mostly originate from areas that have been involved in intensive and effective malaria control programs [1][2][3][4][5] and sustained implementation of health care, with some valuable findings from less well-controlled settings. [6][7][8] It is uncertain if trends of declining transmission intensity are evident across Africa 8 or whether they are apparent in areas where political instability and economic arrest have hindered effective control and surveillance of infectious diseases. 12,13 Conflict and human insecurity pose considerable challenges by causing a breakdown in health delivery systems and a loss of human and financial resources for health programs.…”

Elimination of Malaria Risk through Integrated Combination Strategies in a Tropical Military Training Island

“…Between 1998 and 2004, the incidence of vector-borne malaria cases in Eriteria was reduced substantially with the implementation of insecticide-impregnated mosquito nets, indoor residual spraying, and larval control measures. 16,26 As part of the WHO initiative, Intergrated vector management (IVM) programs are currently being implemented in multiple countries in Africa, and early results of mosquito eradication and disease incidence reduction appears promising. 27 From a public health policy standpoint, this comprehensive program not only reduced the potential threat of mosquitoborne diseases but also the need for anti-malaria chemoprophylaxis.…”