Abstract
Filarial parasites cause over 200 million infections globally. Filarial morbidity was presumably limited to the skin, eyes, and lymphatic vessels but it was recently shown that Onchocerca volvulus infection also induces neurological disease, especially in children. Additionally, adverse outcomes have been observed in women and children when infection with O. volvulus or M. perstans is present during pregnancy. It has been reported that following in utero exposure to filarial parasites (including O. volvulus and M. perstans), the immune response of the foetus becomes more tolerant to these parasites such that they are not promptly cleared from the body during future infection. This phenomenon of 'parasite tolerance' increases the risk for earlier and more intense filarial infections in the child, thereby fostering poor (brain) health and potentially neurological disease. The recent discovery of the OVRV1 virus within O. volvulus suggests a possible mechanism for the neurological disorders observed in onchocerciasis, notably cognitive impairment and seizures. This PhD research will investigate the clinical implications of this virus on the pregnancy outcome and baby health in endemic settings.
The research approach will consist of establishing prospective cohorts of 700 pregnant women in three African countries (Cameroon, Tanzania, South Sudan). These participants will be recruited during antenatal consultations and samples collected (blood and skin snips) to determine baseline exposure/infectious status regarding O. volvulus, M. perstans, and OVRV1. The testing techniques will combine microscopy and rapid diagnostic tests in the field, with more sensitive molecular techniques (LAMP, PCR, ELISA) performed later in the laboratory. The research team will be blinded to the individual paraclinical results of the participants to prevent bias during the future assessment for pregnancy outcomes of the women.
Furthermore, the neurocognitive development of the children born by the participants will be monitored at one year and two years of age, using of the validated inter-NDA cognitive assessment tools. Pregnancy outcomes and child neurocognitive scores will be compared across two groups: women with baseline infection with filarial parasites and/or viruses versus their uninfected peers.
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