Summarybackground To determine the efficacy and acceptability of deltamethrin-impregnated bednets in controlling Chagas disease in South America.

Studies on the protective efficacy of insecticide-treated materials (ITMs) in Plasmodium vivax endemic areas of Latin America have not yielded sufficient evidence for recommendation of their extensive use in the region. Therefore 2 randomized community trials have been conducted on the Pacific Coast of Nicaragua which analysed the minimum coverage of ITMs needed to be effective against malaria. For the characterization of the study area, epidemiological and entomological baseline surveys and household interview surveys were undertaken. Thereafter the communities were paired (6 pairs in the 1st year and 13 pairs in the 2nd year) according to 4-monthly reported malaria incidence rates, population size and bednet coverage, and then randomly allocated to intervention and control groups. In the intervention groups, bednets were impregnated with lambdacyhalothrin; in the control groups, people received general health education. Anopheles albimanus was found to be the main vector with marked indoor biting behaviour late in the evening. P. vivax (99%) clearly outweighed P. falciparum (1%) with low parasite prevalence rates in the asymptomatic general population (8%) and low parasite densities. The protective efficacy of ITMs varied according to the coverage achieved: protective efficacy was 68% in communities with an average ITM coverage of 50% (10 pairs); 31% in communities with an ITM coverage of 16-30% (4 pairs); and no protective efficacy in communities with ITM coverage below 16% (5 pairs). The comparison with other P. vivax endemic areas in Latin America showed that the vector's late biting behaviour and the indoor preference (where ITMs have a repellent effect) probably led to the favourable results in the study. In malaria endemic areas of Latin America, where P. vivax is predominant, studies on vector behaviour should be conducted in order to predict the impact of ITMs on malaria transmission.

SummaryThe consequences of health sector reforms on control of malaria were analysed using Colombia as an example. One of the most complex health sector reform programmes in Latin America took place in the 1990s; it included transferring the vertical vector-borne disease control (VBDC) programme into health systems at state and district levels. A series of studies was undertaken in 1998-2000 at the national level (Ministry of Health Study), at the state level (Departamento Study) and at the health district level (District Study) using formal and informal interviews among control staff and document analysis as data collection tools. A government-financed national training programme for VBDC staff -which included direct observation of control operations -was also used to analyse health workers' performance in the postreform period (longitudinal study). The results showed that some shortcomings of the old vertical system, such as the negative aspects of trade union activity, have not been overcome while some positive aspects of the old system, such as capacity building, operational planning and supervision have been lost. This has contributed to a decrease in control activity which, in turn, has been associated with more malaria cases. Malaria control had to be reinvented at a much larger scale than anticipated by the reformers caused by a whole series of problems: complex financing of public health interventions in the new system, massive staff reductions, the difficulty of gaining access to district and state budgets, redefining entire organizations and -in addition to the reforms -introducing alternative strategies based on insecticide-treated materials and the growth of areas of general insecurity in many parts of Colombia itself. However, positive signs in the transformed system include: the strengthening of central control staff (albeit insufficient in numbers) when transferred from the Ministry of Health to the National Institute of Health, the opportunities offered by the Basic Health Plan (PAB) for new planning initiatives and intersectoral co-operation and the integration of malaria diagnosis and treatment into the general health services (associated with a decrease of malaria mortality). The potentials of the new system have not yet been fully exploited: capacity building, communication and management skills need to be improved and it require guidance from the national level.