Myanmar ICEMR Malaria Cohort

Background: Countries in the Greater Mekong Subregion have committed to eliminate Plasmodium falciparum malaria by 2025. Subclinical malaria infections that can be detected by highly sensitive PCR testing in asymptomatic individuals represent a potential impediment to this goal, although the extent to which these low-density infections contribute to transmission is unclear. To understand the temporal dynamics of subclinical malaria in this setting, a cohort of 2,705 participants from 3 epidemiologically distinct regions of Myanmar was screened for subclinical P. falciparum and Plasmodium vivax infection using ultrasensitive PCR. Standard rapid diagnostic tests (RDTs) for P. falciparum were also performed. Individuals who tested positive for malaria by usPCR were followed for up to 12 weeks. If low-density infections are shown to represent a significant source of transmission, identification of high-risk groups and locations may aid elimination efforts.

Objectives:

To make a preliminary assessment of the dynamics of subclinical malaria detected by ultrasensitive PCR in Myanmar and along its borders with China and Bangladesh.
To test for association between demographic and other risk factors (e.g. occupation, travel) and prevalence and count (rate) of subclinical malaria infection

Methodology:

Geographic Location/Study Sites: Monywa Township in Myanmar’s Sagaing Region, Laiza Township in Kachin State, located on Myanmar’s border with China’s Yunnan, Ann Township in Myanmar’s Rakhine State

Dates of data collection: Data was collected between August 2018 - June 2019

Study Design: Prospective cohort study, with follow-up every 2-4 weeks for up to 4 weeks for uninfected individuals and up to 12 weeks for infected individuals

Eligibility Criteria:

Inclusion criteria
Age at least 6 months old
Provision of a written informed consent or assent as appropriate
Ability and willingness to comply with the study protocol

Exclusion criteria
Any clinical presentations that required immediate medical attention

Data Collection:

Questionnaire data collection: After informed consent was obtained, demographic, medical and malaria history, behavioral, and travel/mobility-related information were collected following a standardized questionnaire, using Open Data Kit (ODK) software, and uploaded to an On a server and stored in a secure cloud storage platform at Duke University. Potential risk factors for malaria infection collected at baseline and during the follow-up period were age, gender, date of study data and sample collection (peak season is June-December, non-peak season is January-May), residence (defined as living in the study village for at least 6 months), type of occupation (dependent, student, soldier, refugee, farmer, plantation worker, or other, where “dependent” refers to a participant who did not work), setting of occupation (predominantly indoors versus predominantly outdoors), the presence of seasonal variation in primary occupation, and regular use of a bed net, defined as at least 4 nights per week. Travel patterns that were potentially related to malaria exposure were also investigated, including the distance from home to place of work or study, greatest distance traveled in a typical day, frequency of travel outside of the village in the last 6 months, mode of travel (non-motorized or motorized vehicle), whether the participant stayed overnight at work, and frequency of exposure to known potential source of malaria, such as water source and forest. The presence of clinical symptoms associated with malaria within the past 2 months and the past 24 hours was investigated, including headache, body ache, nausea, vomiting, abdominal discomfort, decreased appetite, fatigue, fever with chill and rigor, and fever. Oral/axillary temperature was taken and recorded at baseline and during follow-up visits, and fever was defined as temperature > 99.5 °F.

Biological sample collection: For the diagnosis of patent P. falciparum malaria infection, finger prick blood was tested by WHO-qualified RDT (Alere Malaria Ag P.f, Standard Diagnostics Bioline Inc., Gyeonggi-do, Republic of Korea) at baseline and any time during study follow-up as clinically indicated. Finger prick blood was spotted onto Whatman 903 and 3MM filter paper at baseline, during scheduled follow-up visits and unscheduled visits for ill symptoms, air-dried, and labeled with a unique participant identification number, initials of blood collector, and date and time of blood collection. These dried blood spot (DBS) samples were stored in individual sealed plastic bags with desiccant in a temperature-controlled facility until transported to central laboratories for molecular analysis.

Study Documentation:

Myanmar ICEMR baseline CRF

Myanmar ICEMR follow-up CRF

Myanmar ICEMR drug resistance codebook

Myanmar ICEMR study codebook

Myanmar ICEMR README

ClinEpiDB Data Integration: Data files were provided to ClinEpiDB as flat files. Administrative columns were dropped from presentation on ClinEpiDB.org. All dates were obfuscated per individual through the application of a random number algorithm that shifted dates no more than seven days to comply with the ethical conduct of human subjects research.

Acknowledgements:

Financial Support:

Funder: National Institutes of Health (NIH)

Grant Title: Myanmar Regional Center of Excellence for Malaria Research

Ethics Statement: All study procedures were approved by the ethical review boards at Duke University Medical Center (Protocol No. Pro00091895), Department of Medical Research, Myanmar, the Defense Services Medical Research Centre, Myanmar and the National Institute of Parasitic Diseases, China CDC.

Last updated: 08 Dec 2022A longitudinal cohort study of malaria was conducted in Myanmar. Participants >6 months of age were recruited and followed every 2-4 weeks for up to 4 weeks for uninfected individuals and up to 12 weeks for infected individuals. Dried blood spot samples were collected and analyzed by ultra sensitive PCR.