Mastomys natalensis and M. coucha are commensal rodent species endemic to Africa. A recent taxonomic revision within Mastomys leaves the parasite–host list of M. natalensis questionable and that of M. coucha incomplete. The current study aimed to develop a better understanding of the ectoparasite diversity associated with the 2 distinct but closely related rodent species and to explore the influence of host and habitat type on ectoparasite infestations. Between 2014 and 2020, 590 rodents were trapped in 3 habitat types (village, agriculture and natural) across a wildlife-human/domestic animal interface. In total 48 epifaunistic species (45 ectoparasitic and 3 predatory) represented by 29 genera from 4 taxonomic groups (fleas, lice, mites and ticks) were recorded. Only 50% of the epifauna were shared between the 2 rodent species, with mites the most speciose taxon in both host species. The abundance of epifaunistic individuals, and also those of mites and fleas, were significantly higher on male M. natalensis, while ticks were significantly higher on reproductively active M. natalensis. For both rodent species, infestations by most epifaunistic taxa (on M. natalensis) and some taxa (on M. coucha) were significantly lower in the village as opposed to the less disturbed agricultural and natural habitat types. The study highlights the importance of host life history, even in closely related rodent species, in shaping parasite profiles and a loss of parasite diversity in more extreme anthropogenic habitats.

Litomosoides carinii-infected Mastomys natalensis were treated 85 days post infection with cyclosporin A (CyA) or 8 derivatives with different immunosuppressive capacities. CyA (oral doses of 5x25 mg/kg. 5x50 mg/kg, 5x80 mg/kg on consecutive days) reduced parasitaemia levels in a dose dependent way, beginning 3 weeks after first drug administration. Using 5x50 and 5x80 mg/kg animals were free from circulating microfilariae on the day of necropsy (day 56). Derivatives were administered in 5 daily oral doses of 50 mg/kg. Compounds B–5–49 and G–7–53 had similar effects as CyA. Compounds A–4–16 and E–6–44 caused mean microfilaraemia reductions of about 80% until day 56. Compounds C–5–34, D–6–45, F–7–62 and H–7–94 were only marginally effective (10–40%). None of the drugs affected the number or the motility of adult worms. However, in the case of efficacious compounds the number of intrauterine microfilariae was considerably reduced and most of the intrauterine stages were pathologically altered. The efficacy of the various derivatives was independent of their immunosuppressive activity in vivo and in vitro, their anti-inflammatory activity and their activity against Plasmodium berghei. Effects on intrauterine stages were first detectable 7 days after treatment with 5x80 mg CyA/kg when the number of intrauterine microfilariae had decreased and the proportion of pathologically altered stages had increased. Alterations increased with time after treatment. Additionally, the uteri contained relatively large amounts of highly active microfilariae which were still included in an ovoid sheath. These stages seemed to try unsuccessfully to stretch their stiff sheath, and also degenerated by 35 days.