Babesia microti and Malaria Infection in Africa: A Pilot Serosurvey in Kilosa District, Tanzania

Abstract

is a tick-borne intraerythrocytic parasite that is clinically and diagnostically similar to malaria parasite, conferring risk of misdiagnosis in areas where both parasites are endemic. Data on in humans in Africa are lacking, despite evidence that it is present in regional animal populations. Samples that were collected in November 2014 to July 2015 in Kilosa district, Tanzania, were evaluated for evidence of malaria and infection. Clinical data and laboratory samples (i.e., hemoglobin, rapid diagnostic testing [RDT] for malaria, peripheral blood smear, and dried blood spots) from a routine survey were available for analysis. Dried blood spots were tested using an investigational enzyme linked immunosorbent assay (ELISA) against . A total of 1,030 children aged 1 month to< 5 years were evaluated; 186 (18.1%) were malaria RDT positive, 180 (96.8%) of whom had peripheral smears reviewed; 70/180 (38.9%) were smear positive for parasites. The median (inter quartile range) and range of ELISA signal to cutoff (S/C) ratio was 0.10 (0.06-0.15) and 0.01-1.65, respectively; the S/C ratios were significantly higher in subjects ≥ 1 year as compared with those< 1 year old ( < 0.001). There was also a statistically significant association between a positive RDT for malaria and the S/C (median 0.09 versus 0.13 in RDT negative versus RDT positive, respectively; < 0.001). The highest S/C ratios were disproportionately clustered in a few hamlets. The findings suggest that may be present in Kilosa district, Tanzania. However, serological cross-reactivity and false positivity, notably between and spp., cannot be definitively excluded and have implications for testing in other settings.

Fatal Human Babesiosis in a Nine-Year Old Nigerian Girl

“…Our patient had no history of previous blood transfusion, thus tick-borne transmission is likely although the possible risk of contact with ticks was not established. The clinical presentation of babesial infection is clinically and diagnostically similar to that of malaria, [3,11,12] which is often mild or Fig. 1a.…”

“…Babesia is a zoonotic, intraerythrocytic parasite transmitted to humans either by ticks or via infected blood and blood products. Human babesiosis is reported to be endemic in Northeast America [1] but only sporadic human infections have been reported in Africa, Asia, South Americaand Europe [2][3][4][5].…”

A Review of Human Babesiosis and the Laboratory Diagnosis

“…Nearly 30 cases of Babesia infection have been reported in Africa, which diversely distributed in Tanzania, Mozambique, Egypt, and South Africa. The species of babesiosis in human has not been completely determined [21].…”

The Babesia observational antibody (BAOBAB) study: A cross-sectional evaluation of Babesia in two communities in Kilosa district, Tanzania

“…An expanding repertoire of highly sensitive Babesia diagnostic assays affords opportunity for global surveillance for this neglected pathogen. This motivated for a pilot study in Africa [23] where, despite a paucity of Babesia surveillance data in humans, there was plausible evidence that Babesia was present [24–27]. Babesia’s presence in ticks and its role as a significant veterinary pathogen in Africa, is well established [24–26, 28–30].…”

“…The pilot study, which evaluated dried blood spots from 1–5 yr old children in Kilosa District, Tanzania, using a B . microti ELISA assay, demonstrated clustering of individuals with high signal to cutoff (S/CO) ratios in a relatively small number of hamlets and an increase in seroreactivity with age [27]. While suggestive of local exposure, in the absence of confirmatory and ancillary testing, the results were viewed as preliminary.…”