Asymptomatic falciparum and Non-falciparum Malarial Parasitemia in Adult Volunteers with and without HIV-1 Coinfection in a Cohort Study in Western Kenya

Abstract

Asymptomatic malarial parasitemia represents the largest reservoir of infection and transmission, and the impact of coinfection with HIV-1 on this reservoir remains incompletely described. Accordingly, we sought to determine the prevalence of asymptomatic malarial parasitemia in Kombewa, Western Kenya, a region that is endemic for both malaria and HIV-1. A total of 1,762 dried blood spots were collected from asymptomatic adults in a cross-sectional study. The presence of parasitemia was first determined by a sensitive Plasmodium genus–specific 18S assay, followed by less sensitive species-specific DNA-based quantitative polymerase chain reaction (PCR) assays. The prevalence of asymptomatic malarial parasitemia by 18S genus-specific PCR assay was 64.4% (1,134/1,762). Of the 1,134 malaria positive samples, Plasmodium falciparum was the most prevalent species (57.4%), followed by Plasmodium malariae (3.8%) and Plasmodium ovale (2.6%) as single or mixed infections. As expected, the majority of infections were below the detection limit of microscopy and rapid diagnostic tests. HIV-1 prevalence was 10.6%, and we observed a significant association with malarial parasitemia by χ2 analysis (P = 0.0475). Seventy-one percent of HIV-1 infected volunteers were positive for Plasmodium 18S (132/186), with only 29% negative (54/186). In HIV-1-negative volunteers, the proportion was lower; 64% were found to be positive for 18S (998/1,569) and 36% were negative (571/1,569). Overall, the prevalence of asymptomatic malarial parasitemia in Western Kenya is high, and knowledge of these associations with HIV-1 infection are critically important for malaria elimination and eradication efforts focused on this important reservoir population.

Initiation of anti-retroviral/Trimethoprim-Sulfamethoxazole therapy in a longitudinal cohort of HIV-1 positive individuals in Western Kenya rapidly decreases asymptomatic malarial parasitemia

“…ovale positive samples (84.6%) were detected in the absence of other infecting parasite species. As in our previous cross sectional study ( Kifude et al., 2021 ), and like other previous studies within the region ( Howes et al., 2011 ), no P. vivax infections were detected in this population.…”

“…Malaria parasite transmission in this region occurs throughout the year with an estimated entomological inoculation rate for P. falciparum of 31.1 infectious bites per person per year ( Ndenga et al., 2006 ). Our previous cross-sectional surveillance study of adults from 2015 and 2018 revealed no significant differences in prevalence of parasitemia during the study period ( Kifude et al., 2021 ). In this study, enrollment of volunteers occurred between August 2018 and November 2019.…”

“…Of these samples, 1835 were successfully tested for Plasmodium spp. by our genus specific 18S qPCR assay as previously described ( Kifude et al., 2021 ). Malaria prevalence based on 18S qPCR assay was significantly higher in the HIV-1 negative group (61.39%, 345/562, p =0.0001, one way ANOVA with Tukey’s correction) compared to both the HIV-1 positive newly diagnosed 36.52 (278/761) and HIV-1 positive on treatment 31.45% (161/512).…”

“…For all participants, complete blood count (CBC; Coulter AcT5Diff AL hematology analyzer, Beckman Coulter Diagnostics), CD4+ T cell count (PIMA CD4 analyzer, Abbott), and malaria RDT tests were performed at M0 and during all scheduled monthly follow-up visits. In addition, 50 μl blood samples were collected on Whatman ® 903 Protein Saver filter paper cards (GE Healthcare Life Sciences, Chicago, IL, USA), immediately air-dried, and stored at -80°C for subsequent qPCR assays for malaria parasitemia and speciation as described ( Kifude et al., 2021 ).…”

“…In areas where malaria is endemic, many people can harbor parasite infection without overt illness (i.e., asymptomatic infection). Notably, our earlier cross-sectional studies showed that apparently healthy HIV-1 positive adults exhibited higher asexual malarial parasitemias ( Kifude et al., 2021 ) and gametocytemias ( Stiffler et al., 2021 ) compared to adults with malaria only. In the present study, we have extended these observations by recording the incidence, persistence, and prevalence of asymptomatic parasitemia over time in HIV-1 co-infected volunteers and in volunteers without HIV-1 infection.…”