Malaria in the Amazon region: knowledge, practices, prevalence of parasitaemia and entomological evaluation in May, 1997

Abstract

A study of malaria epidemiology was carried out in the Amazonas Department (Colombia). The study's aims were to measure the state of knowledge and practice regarding malaria frequency and control techniques among people iiving in Arica (a village on the banks of the Putumayo river) and to evaluate the prevalence of positive malaria blood smears taken from people living in this village. Malaria surveillance data forthe Amazonas (¡.e. that available for 1996) was also analysed. Using focus groups, it was found that most people identify malaria as being a mosquito-borne disease, but, in a house-tohouse survey made after the focus groups were held, an important proportion of people also believe that contaminated water could be a potentiai source of infection. 8% of people presenting recent febrile illness were positive for malaria (blood smear). Those people involved in activities related to coca growing and collection had a higher prevalence (27%) while those who were not involved in such activities were al1 negative for malaria, p<0.001. Anopheles darlingiwas not identified in this area, despite the fact that it is the main malarial vector in other areas of the Amazonas. Anopheles oswaldoi was the only potential malarial vector detected in these villages. Overall, 307 cases of malaria were detected by the surveillance system in 1996 throughout the department. Most cases were caused by Plasmodium vivax (76%); Plasmodium falciparum was found in 24% of the cases. InTarapacá cases of malaria were detected during each month throughout 1996 while in other villages there were some periods having no reported cases. This study shows that malaria transmission is unstable in the Amazonas department excepting Tarapacá where transmission is permanent. We can support that most cases are caused by Plasmodium vivax while an important proportion of people living in risk areas is unaware of how the disease is transmitted. Also, we found that people involved in coca growing in the jungle have the highest risk for malaria and they can be an important factor in the maintenance of malaria in these communities