Abstract
BackgroundCountries aiming for malaria elimination require a detailed understanding of the current intensity of malaria transmission within their national borders. National household sample surveys are now being used to define infection prevalence but these are less efficient in areas of exceptionally low endemicity. Here we present the results of a national malaria indicator survey in the Republic of Djibouti, the first in sub-Saharan Africa to combine parasitological and serological markers of malaria, to evaluate the extent of transmission in the country and explore the potential for elimination.MethodsA national cross-sectional household survey was undertaken from December 2008 to January 2009. A finger prick blood sample was taken from randomly selected participants of all ages to examine for parasitaemia using rapid diagnostic tests (RDTs) and confirmed using Polymerase Chain Reaction (PCR). Blood spots were also collected on filter paper and subsequently used to evaluate the presence of serological markers (combined AMA-1 and MSP-119) of Plasmodium falciparum exposure. Multivariate regression analysis was used to determine the risk factors for P. falciparum infection and/or exposure. The Getis-Ord G-statistic was used to assess spatial heterogeneity of combined infections and serological markers.ResultsA total of 7151 individuals were tested using RDTs of which only 42 (0.5%) were positive for P. falciparum infections and confirmed by PCR. Filter paper blood spots were collected for 5605 individuals. Of these 4769 showed concordant optical density results and were retained in subsequent analysis. Overall P. falciparum sero-prevalence was 9.9% (517/4769) for all ages; 6.9% (46/649) in children under the age of five years; and 14.2% (76/510) in the oldest age group (≥ 50 years). The combined infection and/or antibody prevalence was 10.5% (550/4769) and varied from 8.1% to 14.1% but overall regional differences were not statistically significant (χ2 = 33.98, p = 0.3144). Increasing age (p < 0.001) and decreasing household wealth status (p < 0.001) were significantly associated with increasing combined P. falciparum infection and/or antibody prevalence. Significant P. falciparum hot spots were observed in Dikhil region.ConclusionMalaria transmission in the Republic of Djibouti is very low across all regions with evidence of micro-epidemiological heterogeneity and limited recent transmission. It would seem that the Republic of Djibouti has a biologically feasible set of pre-conditions for elimination, however, the operational feasibility and the potential risks to elimination posed by P. vivax and human population movement across the sub-region remain to be properly established.
Highlights
Countries aiming for malaria elimination require a detailed understanding of the current intensity of malaria transmission within their national borders
Elimination, poses a major challenge in the majority of countries in Africa owing to the intrinsically high transmission intensity within each country’s national borders [1] or in the cases of low transmission areas, threats posed by neighbouring high transmission countries [2], operational constraints posed by fragile health systems that may not reach remote foci of infection [2], the sophistication of current health information systems to identify all cases of clinical and asymptomatic malaria [3], and the ability to meet the immediate increases in financing needs that would be diverted from other health problems [4,5]
P. falciparum sero-prevalence was 9.9% (n = 517) including 46 children aged less than five years (5 infants aged less than 6 months)
Summary
Countries aiming for malaria elimination require a detailed understanding of the current intensity of malaria transmission within their national borders. Elimination, poses a major challenge in the majority of countries in Africa owing to the intrinsically high transmission intensity within each country’s national borders [1] or in the cases of low transmission areas, threats posed by neighbouring high transmission countries [2], operational constraints posed by fragile health systems that may not reach remote foci of infection [2], the sophistication of current health information systems to identify all cases of clinical and asymptomatic malaria [3], and the ability to meet the immediate increases in financing needs that would be diverted from other health problems [4,5]. There have been limited opportunities for countries to assess their technical and operational strengths and weaknesses for elimination unless undertaken as part of very detailed reviews of large amounts of empirical data as implemented recently in Zanzibar, United Republic of Tanzania [9]
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