Prevalence of Asymptomatic Malaria Parasitemia in Odisha, India: A Challenge to Malaria Elimination

Abstract

The prevalence of malaria in India is decreasing, but it remains a major concern for public health administration. The role of submicroscopic malaria and asymptomatic malaria parasitemia and their persistence is being explored. A cross-sectional survey was conducted in the Kandhamal district of Odisha (India) during May-June 2017. Blood samples were collected from 1897 individuals for screening of asymptomatic parasitemia. Samples were screened using rapid diagnostic tests (RDTs) and examined microscopically for Plasmodium species. Approximately 30% of randomly selected samples (n = 586) were analyzed using real-time PCR (qPCR), and the genetic diversity of Plasmodium falciparum was analyzed. The prevalence of Plasmodium species among asymptomatic individuals detected using qPCR was 18%, which was significantly higher than that detected by microscopy examination (5.5%) or RDT (7.3%). Of these, 37% had submicroscopic malaria. The species-specific prevalence among asymptomatic malaria-positive cases for P. falciparum, Plasmodium vivax, and mixed infection (P. falciparum and P. vivax) by qPCR was 57%, 29%, and 14%, respectively. The multiplicity of infection was 1.6 and 1.2 for the merozoite surface protein-1 gene (msp1) and (msp2), respectively. Expected heterozygosity was 0.64 and 0.47 for msp1 and msp2, respectively. A significant proportion of the study population, 105/586 (18%), was found to be a reservoir for malaria infection, and identification of this group will help in the development of elimination strategies.

Asymptomatic malaria remains high among seasonal migrant workers depart to home from malarious areas and may cause a resurgence of malaria transmission at high lands of northwest Ethiopia: a cross-sectional study

“…The result identified that the prevalence of asymptomatic malaria cases was 17.5% (Table 2) with a high proportion of Plasmodium falciparum (71.8%). It was in line with the study conducted in West Armachio district of Northwest Ethiopia and Dilla town in South Ethiopia [43,44] and India [45]and lower than the study conducted in East Shewa zone, Oromia, Ethiopia [46,47], Nigeria [48], Tanzania [49], India [50] and China-Myanmar border, Southeast Asia [51] and higher than the study conducted in Gondar Zuria district of Northcentral Ethiopia and Democratic Republic of Congo [52,53]. The possible reason for the high prevalence of asymptomatic malaria might be due to significant proportion of seasonal migrant farm workers who had repeated malaria exposure due to frequent visits of the farm areas in the previous year or those who came from malaria-endemic areas for harvesting that would facilitate to develop partial immunity and then to carry the parasite for long periods without…”

Asymptomatic malaria remains high among seasonal migrant workers depart to home from malarious areas and may cause a resurgence of malaria transmission at high lands of northwest Ethiopia: a cross-sectional study

“…The result identi ed that prevalence of asymptomatic malaria cases was 17.5% (Table 2) with high proportion of Plasmodium falciparum (71.8%). It was in line with the study conducted in West Armachio district of Northwest Ethiopia and Dilla town in South Ethiopia [43,44] and India [45]and lower than the study conducted in in East Shewa zone, Oromia, Ethiopia [46,47], Nigeria [48],…”

Assessing Asymptomatic Malaria Carriage of Plasmodium falciparum and Non-falciparum Species in Children Resident in Nkolbisson, Yaoundé, Cameroon

“…This difference may be explained by the fact that the study in Ghana was performed on children under the age of 5 years whereas this study was performed on children aged between 6 months and 10 years; therefore, there could have been a possible gain in protective immunity in the older children because malarial protective immunity is acquired over several years [27]. This prevalence was also higher than others reported in India [28], Dakar [29], Tanzania [30] and Pakistan [31].…”