Risk Factors for Malaria Infection in Central Madagascar: Insights from a Cross-Sectional Population Survey

Abstract

Community prevalence of infection is a widely used, standardized metric for evaluating malaria endemicity. Conventional methods for measuring prevalence include light microscopy and rapid diagnostic tests (RDTs), but their detection thresholds are inadequate for diagnosing low-density infections. The significance of submicroscopic malaria infections is poorly understood in Madagascar, a country of heterogeneous malaria epidemiology. A cross-sectional community survey in the western foothills of Madagascar during the March 2014 transmission season found malaria infection to be predominantly submicroscopic and asymptomatic. Prevalence of infection diagnosed by microscopy, RDT, and molecular diagnosis was 2.4%, 4.1%, and 13.8%, respectively. This diagnostic discordance was greatest for infection, which was 98.5% submicroscopic. Village location, insecticide-treated bednet ownership, and fever were significantly associated with infection outcomes, as was presence of another infected individual in the household. Duffy-negative individuals were diagnosed with , but with reduced odds relative to Duffy-positive hosts. The observation of high proportions of submicroscopic infectionscalls for a wider assessment of the parasite reservoir in other regions of the island, particularly given the country's current focus on malaria elimination and the poorly documented distribution of the non- parasite species.

Plasmodium falciparum Parasitemia and Band Sensitivity of the SD Bioline Malaria Ag P.f/Pan Rapid Diagnostic Test in Madagascar

“…These results are generally in agreement with the results of a previous cross-sectional survey of this same study population, in which P. malariae and P. ovale were not detected by microscopy. 20 For the success of malaria control/elimination program in Madagascar, observation of high proportions of SMI infections, particularly the distribution of non-P. falciparum parasite species, should be further assessed. There was one RDT − microscopy + LDR-FMA + sample (P. falciparum parasitemia 774 parasites/μL), which could be considered false negative or may have pfhrp2 deletion.…”

“…Study site, subjects, and protocol. Following on from a previously described cross-sectional survey, 20 longitudinal surveillance of patients seeking treatment for suspected malaria was established in three health centers of Ampasimpotsy, a rural area in the western foothills of Madagascar. During an 11-month period of this surveillance (September 2015-July 2016), 963 samples were analyzed by three diagnostic approaches: RDT, microscopy, and PCR/LDR-FMA.…”

“…The study protocol was approved by the ethical review panels of University Hospitals Case Medical Center, Cleveland, OH; the National Institutes of Health; and the Ministry of Public Health, Madagascar. 20 Malaria infection diagnostics. Patients with a suspected malaria infection seeking treatment at the study health centers were invited to enroll in the study.…”

Novel Insights into Malaria Vector Surveillance in Madagascar Using a Quadrant Enabled Screen Trap (QUEST) and Bloodmeal Detection Assay for Regional Transmission (BLOODART)

“…Collections were performed in the villages of Amparihy and Ambolodina, located in the fokontany of Kambatsoa (Commune Maroharona, Tsiroanomandidy Health District). Epidemiological surveys have been previously performed in this area in partnership with the Madagascar NMCP [35], and are consistent with protocols approved by the Madagascar Ministry of Health for the present study (N°099-MSANP/CE). Additionally, community and household approvals were obtained following fokontany-based meetings prior to initiating all study activities.…”

A Novel Assay for Simultaneous Assessment of Mammalian Host Blood, Mosquito Species, and Plasmodium spp. in the Medically Important Anopheles Mosquitoes of Madagascar

“…These sites exhibit a seasonal transmission trend (beginning in November-December and peaking in April-May) and are largely characterized by submicroscopic infection. 40 The barrier screen technique was used near Malagasy Zebu (Bos taurus indicus) corrals nestled within the villages. Pyrethroid spray catch was conducted by clearing a human dwelling, laying down a white sheet, and applying pyrethroid insecticides to the walls and ceiling.…”