Malaria epidemiology in central Myanmar: identification of a multi-species asymptomatic reservoir of infection

Abstract

BackgroundThe spread of artemisinin-resistant Plasmodium falciparum is a global health concern. Myanmar stands at the frontier of artemisinin-resistant P. falciparum. Myanmar also has the highest reported malaria burden in Southeast Asia; it is integral in the World Health Organization’s plan to eliminate malaria in Southeast Asia, yet few epidemiological data exist for the general population in Myanmar.MethodsThis cross-sectional, probability household survey was conducted in Phyu township, Bago Region (central Myanmar), during the wet season of 2013. Interviewers collected clinical and behavioural data, recorded tympanic temperature and obtained dried blood spots for malaria PCR and serology. Plasmodium falciparum positive samples were tested for genetic mutations in the K13 region that may confer artemisinin resistance. Estimated type-specific malaria PCR prevalence and seroprevalence were calculated, with regression analysis to identify risk factors for seropositivity to P. falciparum. Data were weighted to account for unequal selection probabilities.Results1638 participants were sampled (500 households). Weighted PCR prevalence was low (n = 41, 2.5%) and most cases were afebrile (93%). Plasmodium falciparum was the most common species (n = 19. 1.1%) and five (26%) P. falciparum samples harboured K13 mutations. Plasmodium knowlesi was detected in 1.0% (n = 16) and Plasmodium vivax was detected in 0.4% (n = 7). Seroprevalence was 9.4% for P. falciparum and 3.1% for P. vivax. Seroconversion to P. falciparum was 0.003/year in the whole population, but 16-fold higher in men over 23 years old (LR test p = 0.016).DiscussionThis is the first population-based seroprevalence study from central Myanmar. Low overall prevalence was discovered. However, these data suggest endemic transmission continues, probably associated with behavioural risk factors amongst working-age men. Genetic mutations associated with P. falciparum artemisinin resistance, the presence of P. knowlesi and discrete demographic risk groups present opportunities and challenges for malaria control. Responses targeted to working-age men, capable of detecting sub-clinical infections, and considering all species will facilitate malaria elimination in this setting.

Asymptomatic and sub-microscopic malaria infection in Kayah State, eastern Myanmar

“…Plasmodium vivax was the most prevalent species among asymptomatic cases in this study, similar to the distribution of malaria species reported in other works [11, 12]. However, a recent study in central Myanmar reported the low prevalence of asymptomatic malaria infection, with a predominance of P. falciparum [28]. The difference likely reflects the heterogeneity of malaria species distribution in central Myanmar.…”

Contribution of Plasmodium knowlesi to Multispecies Human Malaria Infections in North Sumatera, Indonesia

“…To overcome cross-amplification of P. vivax isolates with ribosomal gene PCR assays [3, 19], Ghinai et al [30] have recently described a PCR-sequencing approach to detect P. knowlesi cytb DNA, which also provided satisfactory sensitivity. However, our sicavar target assay provides greater sensitivity for P. knowlesi identification in our hands and was effective in detecting submicroscopic parasites.…”

Variation in Anopheles distribution and predictors of malaria infection risk across regions of Madagascar

“…Age of individuals included in the analysis was divided into four groups: under 5 years (reference category), 5-14 years, 15-64 years, and 65+ years. This breakdown was motivated by the literature (38)(39)(40) that often show distinct differences in malaria prevalence across these age groups. Many data sources speci cally sample children under 5, because they often bear the highest malaria mortality (41).…”