Assessment of the Influence of Primate Species, Deforestation, and Tree Cover on Malaria Transmission in Latin America

Abstract

Despite decreasing incidence worldwide and near eradication in some countries in the 1960s, malaria transmission in the Americas remains high. Various factors have been implicated in the resurgence and continued transmission of malaria in the Americas. High infection rates among non-human primates and the ease of cross-infectivity intimate human-primate overlap as one influencer of malaria incidence. Deforestation, which also increases vector biting rates and fecundity, brings humans into closer contact with primates. Forest cover is another important regulator of Anopheline habitat and survival, and therefore malarial incidence. This study attempts to extend the understanding of these factors in two parts. The first part strives to provide an updated survey of simian malaria levels in Colombia, where no monkey has been analyzed in over 50 years. The second assesses these various risk factors and determines their level of correlation with human malaria transmission in Brazil by constructing linear regressions. Results from primate surveys in Colombia were inconclusive, and more comprehensive methods are necessary in order to accurately determine infection levels of primates. Regressions demonstrated that primate species richness is extremely correlated with human malaria transmission, but not with P. vivax more so than other malarias, as would be expected if monkey presence were leading to spillover. While deforestation was not correlated with malaria incidence, tree cover was highly correlated with both primate species richness and human malaria transmission, and the stronger correlation between cover and P. vivax than cover and P. falciparum may indicate increased simian to human transfer. In sum, deforestation and tree cover seem intricately related to malaria transmission. They may indicate that some primate species thrive following deforestation and may potentially be more influential in malaria transmission. Incorporating the influence of vectors into the regression analysis may provide the missing link, especially if a predominately sylvatic but human proficient Anopheline can be discovered.