Arvicanthis niloticus

Sadlova, Jovana, Vojtkova, Barbora, Hrncirova, Katerina, Lestinova, Tereza, Spitzova, Tatiana, Becvar, Tomas, Votypka, Jan, Bates, Paul & Volf, Petr, 2019, Host competence of African rodents Arvicanthis neumanni, A. niloticus and Mastomys natalensis for Leishmania major, International Journal for Parasitology: Parasites and Wildlife 8, pp. 118-126 : 120-122

3.2. Experimental infections and xenodiagnosis with A. niloticus

Twelve A. niloticus of both sexes were inoculated with the strain

LV109 originating from Senegal. Six A. niloticus (3 males and 3 females)

were infected with sand fly-derived Leishmania (experimental group A) and the same numbers of animals were infected with culture-derived promastigotes (experimental group C), but one animal from group C died early during the experiment and thus was not evaluated. In both groups, the first external signs of the disease appeared on inoculated ear pinnae on week 6 p. i. The affected area was characterized by mild flaking of the skin and hyper-pigmentation ( Fig. 1C ). The pigmentation was lost in the centre while the borders remained hyper-pigmented in some of the animals ( Fig. 1D , Table 3). These dry lesions increased to 3–4 mm by weeks 12– 14 p. i; then, in 3 animals the lesion size remained

Group A, rodent infections initiated with sand fly-derived Leishmania ; Group C, rodent infections initiated with culture-derived promastigotes.

constant until the end of the experiment by week 25 p. i., while in the others, lesions decreased or completely disappeared ( Table 3).

PCR confirmed the presence of Leishmania in 4 of 11 animals, with localization in ears, forepaws, hindpaws and tail ( Table 1). The numbers of detected parasites were higher (hundreds to thousands) in the animal killed on week 12 p. i., while no parasites or only low numbers (around one hundred) were present in organs dissected on week 25 p. i. (at the end of the experiment). This fact corresponds with results of xenodiagnoses: like in A. neumanni , the period of infectiousness of A. niloticus to P. duboscqi was restricted to weeks 5 and 10 p. i. (4.1% and 10.0% of sand fly females became infected, respectively) while no females developed Leishmania infection in feeding experiments on weeks 15– 25 p. i. ( Table 2).

Figures

Fig. 1. Xenodiagnosis and external manifestation of L. major in rodents. Direct xenodiagnosis with P. duboscqi in plastic tubes covered with fine mesh held on the ear of the anaesthetized A. niloticus (A) and external manifestation of L. major LV109 in ear pinnae (site of inoculation) of A. neumanni by week 10 p.i., (B); A. niloticus by week 30 p.i. (C, D) and M. natalensis by week 19 p.i. (E).