Furcifer labordi

Eckhardt, Falk, Strube, Christina, Mathes, Karina A., Mutschmann, Frank, Thiesler, Hauke, Kraus, Cornelia & Kappeler, Peter M., 2019, Parasite burden in a short-lived chameleon, Furcifer labordi, International Journal for Parasitology: Parasites and Wildlife 10, pp. 231-240 : 234-236

4.1. Furcifer labordi in nature

As predicted, among wild living specimens of F. labordi , we detected a massive increase of gastrointestinal parasites related to prevalence and mixed infections over the reproductive period towards the dry season. A similar pattern of decline in immune function was reported for feral Soay sheep Ovis aries (Hayward et al., 2009) . In contrast, Hämäläinen et al. (2015) found that parasite prevalence and morphotype richness decreased with increasing age in a small and relatively short-lived primate species ( Microcebus murinus ), indicating acquired immunity by older specimens. Besides, studies focusing on parasite infection with regard to aging in the wild are lacking. However, the detected increase of prevalence of gastrointestinal parasites according to time is probably linked to a decrease in immune functioning in F. labordi . We also found that males, but not females, of F. labordi showed a remarkable increase of oocyst shedding towards the end of the reproductive season. Concerning the prevalence of coccidian oocysts in the fecal samples, Modrý et al. (2000) found that 32.5% of 83 examined chameleon specimens from east Africa were infected with coccidians, which is similar to our findings in both species. Additionally, in a coproscopic study on chameleons in captivity, Biallas (2013) found that Isospora was regularly detected (21.7%). Accordingly, coccidians in general seem to be frequent gastrointestinal parasites in both, wild living and caged chameleons. Isospora sp. was the most commonly detected gastrointestinal parasite taxon in our study, but we may not have detected all kinds of gastrointestinal parasites, such as trematode eggs, that are too heavy to float during the flotation process in saturated NaCl solution. In their study, Morsey et al. (2012) found that 26.1% of 115 specimens of the common chameleon, Chamaeleo chamaeleon , were naturally infected with the digenetic trematode Postorchigenes sp. and 32.1% with Malagashitrema sp. Thus, the number of gastrointestinal parasite taxa and their prevalence might be underestimated in our study. Moreover, as the samples were stored in ethanol, a detection of intestinal flagellates and ciliates was not possible. Although these groups are mostly considered as commensals, under physiological stress, they can have a severe effect on the host ( Schneller et al., 2008).

Regarding blood parasites, we detected filarias belonging to the genus Foleyella . Here, we detected an increase of prevalence towards the dry season, which might have a severe influence on the individual's health. However, little is known about the clinical signs of foleyellosis in chameleons. Higher mortality rates were noted in Foleyella -infected chameleons than in uninfected animals, which were transported from a tropical to a temperate zone ( Brygoo, 1963). In their study, Maia et al. (2014) report a relatively high incidence of filarial infections in the Malagasy chameleon genus Furcifer , which we reported as well.

Concerning ectoparasites, we first detected acarian infestation in January, when humidity was relatively high. Their prevalence was highest in February and March, but decreased towards the dry season, eventually decreasing to zero. Thus, their detection seems to be highly associated with the rainy season, when chameleons are still in good physical conditions. In their study of the impact of tick load on the fitness of their lizard hosts, Bull and Burzacott (1993) did not find any influence on the longevity of the sleepy lizard Tiliqua rugosa . In addition, we found that trombiculids were obviously restricted to axillary situated so called “mite pockets”.

At first sight, mite pockets are paradoxical structures as they seem to provide an optimal environment for the mites, giving protection from solar radiation, high temperatures, desiccation, and offering easily penetrated skin. Here, the most likely hypothesis for their function is that they reduce damaging effects of mite infestations ( Arnold, 1986). Mites are probably attracted to the pockets because they provide ideal conditions, whereas in return these invaginations appear to ameliorate much of their potential damage. These pockets have a large internal area of exposed skin compared with their volume, which enables large numbers of mites to be concentrated in places where they do not interfere with general cutaneous function. In particular, the epidermis is resilient and recovers rapidly after a mite has fed. The shape of the pocket enables large numbers of lymphoid cells to be concentrated around the feeding mites and it is probable that these cells reduce the effects of antigens and any pathogens introduced by the feeding mites, as well as contributing to their diet. Thus, due to the peak of the infestation in the rainy season and evolutionary adaptation to these parasites, we do not consider acarian infestation as a decisive factor that is influenced by immunosenescence. However, these parasites cause blood loss and are potential vectors for pathogens that can have negative impacts on the health of the host ( Schneller et al., 2008).