Leukocyte Profiles for Western Fence Lizards,Sceloporus occidentalis, Naturally Infected by the Malaria ParasitePlasmodium mexicanum

Abstract

Plasmodium mexicanum is a malaria parasite that naturally infects the western fence lizard, Sceloporus occidentalis , in northern California. We set out to determine whether lizards naturally infected with this malaria parasite have different leukocyte profiles, indicating an immune response to infection. We used 29 naturally infected western fence lizards paired with uninfected lizards based on sex, snout-to-vent length, tail status, and the presence-absence of ectoparasites such as ticks and mites, as well as the presence-absence of another hemoparasite, Schellackia occidentalis. Complete white blood cell (WBC) counts were conducted on blood smears stained with Giemsa, and the proportion of granulocytes per microliter of blood was estimated using the Avian Leukopet method. The abundance of each WBC class (lymphocytes, monocytes, heterophils, eosinophils, and basophils) in infected and uninfected lizards was compared to determine whether leukocyte densities varied with infection status. We found that the numbers of WBCs and lymphocytes per microliter of blood significantly differed (P< 0.05) between the 2 groups for females but not for males, whereas parasitemia was significantly correlated with lymphocyte counts for males, but not for females. This study supports the theory that infection with P. mexicanum stimulates the lizard's immune response to increase the levels of circulating WBCs, but what effect this has on the biology of the parasite remains unclear.

The Effect of Plasmodium Floridense on Relative Leukocyte Counts of Anolis Sagrei and A. Carolinensis in Florida, Usa

“…We had predicted that eosinophils would be elevated in infected anoles because they are responsible for protection against protozoal parasites (Strik et al 2007). Similar to Motz et al (2014), we found no such effect, which may mean that eosinophils are not as important in protozoal immunological responses in reptiles as previously assumed. Alternatively, Plasmodium may not elicit an eosinophil response even if other protozoans do, or the low parasitemia of P. floridense in Florida anoles (Perkins et al 2009, Doan et al 2019 may not be enough to cause a detectable eosinophil response.…”

“…In humans, eosinophil levels change dramatically over the course of infection (Kurtzhals et al 1998) and vary with severity of infection (Saidu et al 2015). Motz et al (2014) found no significant difference between Sceloporus occidentalis infected with Plasmodium mexicanum versus uninfected. To our knowledge, no studies have assessed the relationship of eosinophil levels and Plasmodium infection in anoles.…”

Dehydration enhances cellular and humoral immunity in a mesic snake community

“…Here, we used the correlation between these metrics to provide an initial distinction between two alternative possibilities based on work in other squamates. As many parasites illicit an immune response (i.e., inflammation, Murphy, 2012), parasite burden could be positively correlated with humoral and cellular immunocompetence (i.e., a responsive immune effect, Motz, Lewis, & Vardo‐Zalik, 2014; Spence, Durso, Smith, Skinner, & French, 2017). Alternatively, animals with comparatively lower immunocompetence may be more susceptible to parasitism, and thus might have a higher parasite burden (i.e., a causative immune effect).…”

First molecular screening of Plasmodium species in ungulates from Southern Brazil

“…Malaria parasites have been described in a wide range of hosts in the Americas, including humans [1], monkeys [2], free-living birds [3], reptiles [4] and rodents [5]. Among non-primate mammals, Plasmodium species had been thought to be limited to the Old World.…”