Transplacental Transmission of Filarial Infections and Its Impact on Oxidative Stress and Immune Responses during Foetal Life in Bamenda, North West Cameroon

Background: Women commonly harbour filarial infections during their childbearing years, raising the possibility that the developing foetus may be exposed to filarial antigens in the uterus and thereby have altered immunity and susceptibility to infection during early childhood. However, there are no concrete proofs to justify the risk of infections in infants born from mothers having filarial infections during pregnancy.

Aim: The purpose of this study was to assess the prevalence of microfilariae in umbilical cord blood and respective mothers and to evaluate the relationship between the cord blood filarial infection and the oxidative stress status and concentration of IL-2, IL-10, IL-13, INF-γ and IgG in umbilical cord blood.

Methods: This was a nested case–control study of cords and mothers of normal gestational age (>250 days of gestation). A total of 316 pairs of umbilical cords and mothers were examined. The presence of microfilariae was assessed by microscopy in mothers and cords. Oxidative stress status (total oxidative stress and total oxidative defence) and nitric oxide of umbilical cord and mother’s blood were investigated by the colorimetric method. ELISA was carried out for IL-2, IL-10, IL-13, INF-γ in umbilical cord and mother’s blood. Equally, umbilical cords were subjected to ELISA for total IgG.

Results: Results obtained showed that microfilariae had a prevalence of 32.9% and 29.7% in umbilical cord blood and women at time of delivery respectively. High levels of total oxidative stress (TOS) with low total oxidative defence (TAD) was found in filarial infected (Mf +ve) umbilical cord and mother’s blood compared to controls or uninfected (Mf -ve) cords and mothers blood. IL-2 was lower in the blood of microfilariae infected cords and mothers, while INF-γ, IL-13 and IL-10 were higher as compared to microfilariae negative cords and mothers. Equally, plasma total IgG concentration was higher in microfilariae positive cords compared to the negative cords and positively correlated with IL-10.

Conclusions: There is high frequency of transplacental transmission of microfilariae. Cord blood filarial infections were associated with a high TOS, a protective immune response with low IL-2 and high INF-γ, and a typical Th2 immune response that was associated with higher concentration of immune total IgG regulatory cytokine IL-10 and IL-13 in neonate.