Survival and growth of M. perstans larvae in a human colon carcinoma cell line-based in vitro culture.

Mansonella perstans infections are widespread in Sub-Saharan Africa and Central and South America and thus can be considered as the most prevalent parasite of man in tropical Africa. In contrast to the high prevalence, knowledge about the biology of this filarial nematode is restricted and no effective treatment regimens of this ivermectin-resistant parasite is lacking. An obstacle for the research is that M. perstans resides in body cavities and thus have been only rarely recovered during surgery or autopsy. Therefore, alternative methods like in vitro culture systems need to be implemented to decipher the nature of mansonellosis and effective drugs. Previously, we have established a monkey kidney epithelial cell-based in vitro culture for the maintenance of M. perstans infective larvae (L3) up to 77 days. However, no alternative for this culture system have been postulated to allow longer survival rates and development of adult worms in vitro. Thus, we aim to establish an alternative in vitro culture system for M. perstans L3. M. perstans L3 were isolated from engorged and laboratory reared Culicoides midges. The larvae were then cultured in Dulbecco's Modified Eagle Medium supplemented with either 10% foetal bovine serum (FBS), 10% newborn calf serum (NCS) or 1% bovine serum albumin (BSA) together with human colon carcinoma cells (HCT-8) as feeder cells. Survival and growth were recorded. We obtained that the 10% NCS culture condition was superior allowing long-term maintenance of M. perstans L3 for up to 100 days and boosted growth of the parasites for up to 5-folds compared to the initial size at culture inception. Although no moulting of the L3 into L4 or adult worms could be overserved, the human colon carcinoma cell-based in vitro culture provides an alternative platform to analyse M. perstans biology and screen for novel drugs against M. perstans.

Uptake of intermittent preventive treatment of malaria in pregnancy and risk factors for maternal anaemia and low birthweight among HIV-negative mothers in Dschang, West region of Cameroon: a cross sectional study.

BACKGROUND: Approximately 32 million pregnant women are at risk of malaria with up to 10,000 maternal deaths and 200,000 neonates at risk annually. Intermittent Preventive Treatment (IPT) with sulfadoxine-pyrimethamine (SP) is recommended by the World Health Organization (WHO) to reduce disease in pregnancy and adverse maternal and newborn outcomes. At least three doses of SP should be taken by pregnant women during antenatal consultation (ANC) beginning from the thirteenth week of pregnancy till parturition. The aim of this study was to assess uptake of IPT during pregnancy and risk factors for maternal anaemia and infant birth weight in Dschang, West region of Cameroon. METHODS: A total of 380 consenting pregnant women at delivery were recruited in a cross- sectional prospective survey between January to December 2021. Data on ANC attendance, total dose of IPT and history of malaria were abstracted from hospital ANC records while socio-demographic characteristics, bed net use and obstetrics history of each participant were also recorded through an interview. Further, blood samples were collected from the intervillous space for assessment of maternal anaemia and microscopic parasitology. Nested PCR based on amplification of the Plasmodium 18S sRNA was carried out to detect submicroscopic infection. IPTp coverage was calculated per WHO recommendation and the prevalence of anaemia and low birth weight were estimated as proportions in the total sample of pregnant women and live births, respectively. Crude and adjusted odds ratios and their 95% confidence intervals were used to estimate associations between pregnancy outcomes considered and risk factors in specific and general models. A p < 0.05 was considered significant. The R software (V4.1.4) was used for all analyses. RESULTS: A majority of pregnant women was aged between 24 and 34 years old (59.2%) and had secondary education (58.8%). Uptake of ≥ 3 IPTp was 64.99% with 77.20% of all who received at least one IPTp doses taking a mix of SP and DP or DP alone in successive ANC contacts. Those with four or more ANC contacts (73.42%) were more likely to have received at least one IPTp. Furthermore, 13.9% of live births had low birthweights (BW < 2500 g) and one in four parturient women with moderate anaemia by WHO criteria. Microscopy (blood smear examination) and PCR-based diagnosis revealed between 0% and 1.57% of parasite-infected placental samples, respectively. Reported malaria in pregnancy predicted maternal anaemia at birth but not birth weight. Only gestational age (< 37 weeks) and bed net use (< 5 months) significantly predicted infant birth weight at delivery. CONCLUSION: The uptake of WHO recommended IPT doses during pregnancy was moderately high. Reported malaria in pregnancy, poor bed net coverage, gestational age less than 37 weeks adversely affect maternal haemoglobin levels at birth and infant birth weight. Asymptomatic and submicroscopic placental parasite infections was found at low prevalence. Together these results highlight the importance of maintaining aggressive measures to prevent malaria in pregnancy and protect the health of mother and baby.

High prevalence of asymptomatic Plasmodium falciparum malaria in Makenene, a locality in the forest-savannah transition zone, Centre Region of Cameroon.

Malaria transmission and prevalence is still not well documented across Cameroon particularly in medium-sized cities or localities representing high transit zone. Different risk factors could be associated with persistence malaria transmission such as population movement from high to low transmission settings. A cross-sectional community-based study was carried out to determine malaria prevalence and risk factors in Makenene, a small city in a forest-savannah which is a crossroads between different parts of the country where travellers usually stop-over day and night to rest. Using malaria diagnostic test (mRDTs from SD-BIOLINE) and microscopy (thin and thick blood smears), 406 participants from 237 households were tested for malaria infection. The prevalence of malaria was high irrespective of the detection method: mRDT (41.87%) or microscopy (38.42%). At household level, 46.41% of households had at least one case of malaria with an average of 1.41 infected individuals per household. Parasite density was also high with the majority of infected individuals (64.74%) bearing more than 500 parasites/µl. Only Plasmodium falciparum was found. The chances of being infected with malaria parasites was almost the same for all participants irrespective of the sleeping behavior, bednet usage, house type and environmental factors. The study supports high malaria transmission in the locality and the need for additional studies on vectors bionomics and transmission patterns.