Mapping hypoendemic, seasonal malaria in rural Bandarban, Bangladesh: a prospective surveillance

Abstract

BackgroundUntil recently the Chittagong Hill tracts have been hyperendemic for malaria. A past cross-sectional RDT based survey in 2007 recorded rates of approximately 15%. This study was designed to understand the present epidemiology of malaria in this region, to monitor and facilitate the uptake of malaria intervention activities of the national malaria programme and to serve as an area for developing new and innovative control strategies for malaria.MethodsThis research field area was established in two rural unions of Bandarban District of Bangladesh north of Bandarban city, which are known to be endemic for malaria due to Plasmodium falciparum. The project included the following elements: a) a demographic surveillance system including an initial census with updates every four months, b) periodic surveys of knowledge attitude and practice, c) a geographic information system, d) weekly active and continuous passive surveillance for malaria infections using smears, rapid tests and PCR, f) monthly mosquito surveillance, and e) daily weather measures. The programme included both traditional and molecular methods for detecting malaria as well as lab methods for speciating mosquitoes and detecting mosquitoes infected with sporozoites.ResultsThe demographic surveillance enumerated and mapped 20,563 people, 75% of which were tribal non-Bengali. The monthly mosquito surveys identified 22 Anopheles species, eight of which were positive by circumsporozoite ELISA. The annual rate of malaria was close to 1% with 85% of cases in the rainy months of May-October. Definitive clustering identified in the low transmission season persisted during the high transmission season.ConclusionThis demographically and geographically defined area, near to the Myanmar border, which is also hypoendemic for malaria, will be useful for future studies of the epidemiology of malaria and for evaluation of strategies for malaria control including new drugs and vaccines.

Hemoglobin E and Glucose-6-Phosphate Dehydrogenase Deficiency and Plasmodium falciparum Malaria in the Chittagong Hill Districts of Bangladesh

“…The unions consisted of about 24,000 people, divided into 24 geographic clusters of about 2.5 km 2 and similar population sizes of about 1,000 persons. 14,15 Informed consent was obtained from all adult participants and guardians of child participants. This study has been approved by the Johns Hopkins Bloomberg School of Public Health and International Center For Diarrheal Disease Research, Bangladesh (icddr,b) Institutional Review Board (IRB) committees.…”

“…The malaria case definition required a positive RDT or microscopy and was divided between 1) passive case detection when individuals had sought treatment of fever, history of fever, or other symptoms, and were found to have a positive RDT and/or microscopy and 2) active case detection in which individuals tested positive after being randomly selected for RDT/microscopy testing within a predetermined sampling structure according to cluster and age, as used for the larger cohort study. 14,15 From the larger epidemiologic cohort study, 170 passive malaria cases were randomly selected from 472 using a random number generator. 14 All cases detected by active surveillance meeting this criteria from our cohort study were also included in this analysis.…”

Geospatial Technology: A Tool to Aid in the Elimination of Malaria in Bangladesh

“…Through June 2014, there were 17 published studies that have used geospatial technologies (GIS, GPS and/or RS) to understand and predict malaria risks [1,2,8,[13][14][15][16][17][18][19][20][21], develop malaria risk maps, [21,22] and provide findings for targeted interventions strategies in Bangladesh. To supply feedback to the NMCP, national malaria risk maps were produced [2,23].…”

Plasmodium falciparum Genetic Diversity in Bangladesh Does Not Suggest a Hypoendemic Population Structure

“…Administration of antimalarial drugs may force the local parasite population toward a new resistant phenotype by mutation in certain genes, 6 such mutation has been reported from two of the samples of this study. 22 Since the study areas are populated by people of different ethnic groups, 2 this might present different host immune systems for the parasite to withstand, which could generate high genetic diversity. 6 Despite WHO recommendations for the use of msp1, msp2, and glurp as markers in drug efficacy studies 29 and their limited use in the drug efficacy studies in CHT areas of Bangladesh, 19,20 the circulating P. falciparum population genetic structure is still unknown.…”

“…1 Among the 10 malaria-endemic countries of the World Health Organization (WHO) southeast Asian region, Bangladesh is considered as hypoendemic for malaria, 2 and 90% of malaria is caused by Plasmodium falciparum. Of the 64 administrative districts of Bangladesh, 13 districts bordering India and Myanmar are malaria endemic, and of these 13, almost 80% of the malaria cases are reported from Bandarban, Khagrachari, and Rangamati (collectively called Chittagong hill tracts [CHT]).…”