High prevalence of asymptomatic malaria infections: a cross-sectional study in rural areas in six departments in Haiti. (December 2015)

• Record Type: Journal Article
• Authors: Elbadry, Maha; Al-Khedery, Basima; Tagliamonte, Massimiliano; Yowell, Charles; Raccurt, Christian; Existe, Alexandre; Boncy, Jacques; Weppelmann, Thomas; Rochars, Valery; Lemoine, Jean; Okech, Bernard; Dame, John
• Is Part Of: Malaria journal. Volume 14:Number 1(2015)
• Page Start: 1
• Page End: 9
• Publication Date: 2015-12
• Subjects: Malaria -- Haiti -- qRT-PCR -- Diagnostic tools -- Plasmodium falciparum -- RDT; Malaria -- Periodicals; 616.9362
• DOI: 10.1186/s12936-015-1051-2
• Languages: English
• ISSNs: 1475-2875

Abstract

Abstract Background Public health measures are poised for transition from malaria control to malaria elimination on the island of Hispaniola. Assessment of the reservoir of asymptomatic infections from which acute malaria cases may derive is critical to plan and evaluate elimination efforts. Current field technology is ill suited for detecting sub-microscopic infections, thus highly sensitive survey methods capable of detecting virtually all infections are needed. In this study the prevalence of infection withPlasmodium falciparum was determined in patients seeking medical care primarily for non-febrile conditions in six departments in Haiti using a newly designed qRT-PCR-based assay. Methods Three different methods of parasite detection were compared to assess their utility in approximating the prevalence ofP. falciparum infections in the population: malaria rapid diagnostic test (RDT) designed to detect histidine-rich protein 2 (HRP2), thick smear microscopy, and a quantitative reverse transcription polymerase chain reaction (qRT-PCR) assay based upon the small sub-unit ribosomal RNA. The limit of detection of the qRT-PCR assay utilized was 0.0003 parasite/µL of blood. Venous blood was obtained from a total of 563 subjects from six departments in Haiti, all of whom were seeking medical attention without complaints consistent with malaria. Each subject was questioned for knowledge and behaviour using demographic and epidemiological survey to identify risk factors for disease transmission. Results Among the 563 samples tested, ten and 16 were found positive for malaria by RDT and microscopy, respectively. Using the qRT-PCR test to assess the infection status of these subjects, an additional 92 were identified for a total of 108. Based upon the qRT-PCR assay results, a wide variation in prevalence of infection in asymptomatic subjects was seen between geographic locations ranging from 4–41 %. The prevalence of infection was highest in the Grand Anse, Nord and Sud-Est Departments, and demographic data from questionnaires provide evidence for focal disease transmission. Conclusions The qRT-PCR assay is sufficiently sensitive to identify an unexpectedly large number of asymptomatic, submicroscopic infections. Identifying and clearing these infections presents a significant challenge to both control and elimination efforts, but the qRT-PCR assay offers a reliable method to identify them.