Current vector control challenges in the fight against malaria in Brazil

Abstract In Brazil, malaria is an important public health problem first reported in 1560. Historically, fluctuations in malaria cases in Brazil are attributed to waves of economic development; construction of railroads, highways, and hydroelectric dams; and population displacement and land occupation policies. Vector control measures have been widely used with an important role in reducing malaria cases. In this review article, we reviewed the vector control measures established in the Brazilian territory and aspects associated with such measures for malaria. Although some vector control measures are routinely used in Brazil, many entomological and effectiveness information still need better evidence in endemic areas where Plasmodium vivax predominates. Herein, we outlined some of the needs and priorities for future research: a) update of the cartography of malaria vectors in Brazil, adding molecular techniques for the correct identification of species and complexes of species; b) evaluation of vector competence of anophelines in Brazil; c) strengthening of local entomology teams to perform vector control measures and interpret results; d) evaluation of vector control measures, especially use of insecticide-treated nets and long-lasting insecticidal nets, estimating their effectiveness, cost-benefit, and population acceptance; e) establishment of colonies of malaria vectors in Brazil, i.e., Anopheles darlingi, to understand parasite-vector interactions better; f) study of new vector control strategies with impacts on non-endophilic vectors; g) estimation of the impact of insecticide resistance in different geographical areas; and h) identification of the relative contribution of natural and artificial breeding sites in different epidemiological contexts for transmission.

Situação epidemiológica da malária na região amazônica brasileira, 2003 a 2012 / Epidemiological situation of malaria in the brazilian amazon region, 2003 to 2012

OBJETIVO: Descrever a situação epidemiológica da malária na região amazônica brasileira entre 2003 e 2012. MÉTODOS: Este estudo ecológico retrospectivo utilizou dados do Sistema de Informação de Vigilância Epidemiológica e Notificação de Casos de Malária, Sistema de Internações Hospitalares e Sistema de Informações de Mortalidade. Determinaram-se o percentual de Plasmodium falciparum,o número de internações e óbitos e a letalidade por malária em cada ano. Para a infecção pelo P. falciparum, foi avaliada a distribuição dos casos por estado. Os dados de 2012 foram comparados aos de 2005, ano em que a região amazônica notificou um maior número de casos, e aos do ano anterior, 2011. RESULTADOS: Em 2012, foram registrados 241806 casos de malária, representando uma redução de 60,1% em relação a 2005 e de 9,1% em relação a 2011. Entre 2003 e 2005, houve um aumento de 48,3% no número de casos, com registro de 606 069 casos em 2005. Desde 2006, observa-se tendência à redução do número de casos, principalmente na transmissão do P. falciparum, com 155 169 casos notificados em 2005 e 35 385 casos em 2012 (redução de 77,2%). Entre 2005 e 2012, houve redução no número de internações (74,6%) e nos óbitos (54,4%) por malária. CONCLUSÕES: Apesar da redução no número de casos de malária no período analisado, o possível surgimento de parasitos resistentes às drogas e a menor frequência de casos de malária por P. falciparum indicam a necessidade de novas estratégias de vigilância, com utilização de ferramentas de diagnóstico mais sensíveis e manejo integrado de vetores, visando à ousada, mas não impossível, eliminação do P. falciparum.

OBJECTIVE: To describe the epidemiological status of malaria in the Brazilian Amazon region between 2003 and 2012. METHODS: The present retrospective ecological study employed data from the Brazilian Epidemiological Surveillance and Malaria Communication System (SIVEP-Malária/SVS/MS), Hospital Admissions System (SIH/DATASUS/MS), and Mortality Information System (SIM). For each year, the percentage of Plasmodium falciparum cases, the number of admissions, and deaths and lethality due to malaria were determined. The distribution of P. falciparum cases in each state was also described. Data from 2012 were compared to data from 2005, when the Amazon region recorded a peak number of cases, and with data from 2011. RESULTS: In 2012, 241 806 malaria cases were recorded in the region, a reduction of 60.1% vs. 2005 and of 9.1% vs. 2011. Between 2003 and 2005, there was an increase of 48.3% in the number of cases, with 606 069 recorded cases in 2005. Since 2006, a declining trend in number of cases has been observed, especially for P. falciparum, with 155 169 cases notified in 2005 vs. 35 385 in 2012 (reduction of 77.2%). Between 2005 and 2012, the number of malaria hospital admissions (74,6%) and deaths (54,4%) was also reduced. CONCLUSIONS: Despite a decline in the number of malaria cases, the possible emergence of drug-resistant parasites and the lower frequency of P. falciparum indicate the need to adopt new surveillance strategies, more sensitive tools, and integrated vector management to achive a bold, but not impossible, goal: the elimination of P. falciparum.