Malaria Surveillance and Research Studies in Liberia and Guinea-Conakry

National Institute Of Allergy And Infectious Diseases

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Abstract

We have no published findings this year. We have the following findings that we are reporting at the ASTMH 2022 Meeting in Seattle, based on progress made in the clinical study under the approved Protocol 19-I-N141 Cross-Sectional Survey of Plasmodium and Other Parasites in Pregnant Women and Infants Around Maferinyah, Guinea: A cross-sectional survey of Plasmodium falciparum infection is ongoing in Guinea, a sub-Saharan nation in West Africa. The study is being conducted at the Centre de Formation et de Recherche en Sant Rurale in Maferinyah, Forcariah Prefecture, a Partnership of Clinical Research in Guinea (PREGUI) site. Two study populations were recruited from January 2020 for a single study visit: pregnant women (PW) at routine antenatal care (ANC) appointments and infants aged 6 to 12 months at routine Expanded Program on Immunization (EPI) visits. Participants were generally asymptomatic during their study visit. Demographic, socioeconomic, and clinical information was surveyed followed by a malaria rapid diagnostic test (RDT) with results provided to the participants on site and referred for appropriate treatment if positive. In addition, we prepared blood smears and dried blood spot cards from a single finger (or heel) stick blood sample. Future planned assays include malaria PCRs, evaluation of hrp2/3 deletions and antimalarial resistance markers in parasites, and serological assays for helminths. As of 01 June, 2022, 1569 PW and 659 infants enrolled (total 2228). 256 PW (16.3%) had a positive RDT as did 82 (12.4%) infants; 311 (19.8%) PW had a positive BS as did 66 (10.0%) infants. Overall, 338 (15.2%) of total participants had a positive RDT and 377 (16.9%) had a positive BS. These results demonstrate a concerning rate of malaria infection among asymptomatic pregnant women and infants in Maferinyah, Guinea. Continued efforts are needed to increase coverage of effective preventive measures. The following findings were reported at the ASTMH 2021 Meeting for the study in Liberia, based on progress made in the clinical study under the approved Protocol 19-I-N007: Cross-Sectional Survey of Plasmodium and Other Parasites in Pregnant Women and Children around Margibi and Montserrado Counties, Liberia: A cross-sectional survey of Plasmodium falciparum infection was recently completed in Liberia, a sub-Saharan nation in West Africa. The study was conducted at two PREVAIL (Partnership for Research on Vaccines and Infectious Diseases in Liberia) clinical research sites, the first at C. H. Rennie Hospital (CHR) in Kakata (relatively rural) and the second at Duport Road Health Center (DPR) in Monrovia (peri-urban). Enrollments began in October 2019 and continued through January 2021 with a hiatus from April to July of 2020 due to the COVID-19 pandemic. Two study populations were recruited to participate for a single study visit: pregnant women (PW) attending routine antenatal care (ANC) appointments and infants aged 6 to 12 months attending routine Expanded Program on Immunization (EPI) visits. Participants were generally asymptomatic when attend the study visit as they would present to an acute care clinic for episodes of symptomatic malaria rather than attend their ANC or EPI visits. Demographic, socioeconomic, and clinical information was surveyed followed by a malaria rapid diagnostic test (RDT) with results provided to the participants on site and referred for appropriate treatment if positive. In addition, blood smears were performed on a random subset of participants (the first participants each day at each site). Dried blood spot cards were also made from a single finger (or heel) stick blood sample. Future planned assays include malaria PCRs, evaluation of hrp2/3 deletions and antimalarial resistance markers in parasites, and serological assays for helminths. 1121 PW and 141 infants enrolled in total across both sites, with 575 PW and 99 infants enrolled at CHR and 546 PW and 46 infants enrolled at DPR. Of the 575 PW enrolled at CHR, 105 (18.3%) had a positive RDT as did 10 of the 99 infants (10.1%). At DPR, 31 of 546 PW (5.7%) and 4 of 42 infants (9.5%) had a positive RDT. These results demonstrate a concerning rate of malaria infection among asymptomatic pregnant women and infants in these Counties in Liberia. Continued efforts are needed to increase coverage of effective preventive measures. Community Dynamics of Malaria Transmission in Humans and Mosquitoes, Guinea-Conakry, Liberia, Burkina Faso In FY20, plans were made to initiate community transmission epidemiology studies in Guinea-Conakry, Liberia and Burkina Faso as part of the EDCTP TBV Consortium headed by Dr. Issaka Sagara of MRTC, Mali. Studies in all three sites have been initiated over the past year and are currently undergoing monthly surveillance visits. Guinea-Conakry The study in Guinea-Conakry (Protocol #000160) began screening in March 2022 and completed enrollment that month with 399 individuals enrolled. Monthly visits began in April 2022 and gather information regarding malaria transmission based on the rates of blood smear positive individuals by month, season and year at Maferinyah, Guinea. Monthly mosquito collections also began in April 2022 and are ongoing. Liberia The study in Liberia (Protocol #000158 ) began screening in September 2021 and completed enrollment in July 2022 with 396 individuals enrollment. Monthly visits began in April 2022 and gather information regarding malaria transmission based on the rates of blood smear positive individuals by month, season and year at two sites in the Salala district: Marshansue and Fleh-la. Monthly mosquito collections have not yet been initiated in Liberia but should begin by Q4 2022. An amendment to the protocol is currently in process to add direct skin feeding assays on enrolled individuals aged 9 years and older to the monthly visit study procedures. Burkina Faso The study in Burkina Faso was initiated in June 2021 and to 598 individuals in the Sabou district, aged 6 months and older, have been enrolled. Enrollment was completed in early July 2021 and individuals began monthly visits that month. To date just over one year of malaria epidemiology data has been collected. Parasite and gametocyte data are being analyzed from the first transmission season (July-Dec 2021), including the Percent of P. falciparum gametocytemia across the transmission season which peaks in September with the highest levels seen in the 5-18 year old age range. Similarly for asexual P. falciparum parasitemia, infection levels peak in September in 9-18 year old children with over 60% of individuals positive for malaria parasites at the time of their monthly visits. In contrast, younger children have much lower levels of parasite and gametocyte burden and in many cases are more similar to levels seen in the adult population. Mosquito collections began in October 2021 and to date over 3000 live and spray collections have been completed. Over the course of the collections an average of 1.08 blood fed mosquitoes have been collected per visit and multiple Plasmodium falciparum infected mosquitoes have been detected. The study protocol was amended in July 2022 to extend study visits by 6 months which will allow collections to occur through a second transmission season. This extra time will also allow the conduct of direct skin feeding assays and collection of mosquito transmission data which has been delayed due to slower than anticipated construction of the mosquito insectary at the site. The study will now have a completion date of December 2022.