Hidden in plain sight: Cryptic and endemic malaria parasites in North American white-tailed deer ( Odocoileus virginianus )

Abstract

Findings suggest that North American white-tailed deer commonly harbor cryptic infection with the only known New World mammalian Plasmodium.

First molecular screening of Plasmodium species in ungulates from Southern Brazil

“…However, negative findings obtained in this study may depend on the low parasitemia at the time of blood collection. Indeed, low parasitemia has been previously described in infected ungulates [6, 11, 12], and the incidence of infection has been as low as 0.003% [12] in molecular tests, with no detection of parasites in blood smears. Moreover, the life cycle of Plasmodium in vertebrate hosts may include a long-lived dormant stage in the liver, with sequestration of the parasite from the general circulation, causing very low parasitemia in the absence of an immunosuppressed state, as previously reported in water buffalos ( Bubalus bubalis ) [26].…”

“…Conversely, previous studies have failed to detect Plasmodium in other ungulate species, including elk ( Cervus canadensis ), pronghorn ( Antilocapra americana ) and mule deer ( Odocoileus hemionus ) [11]. Additionally, previous PCR-based screening studies on other species of the order Artiodactyla, including sitatunga ( Tragelaphus spekii ), red river hog ( Potamochoerus porcus ) and water chevrotain ( Hyemoschus aquaticus ), also did not detect Plasmodium sp.…”

“…divergence have shown that the clade including P. odocoilei is likely to have diverged from other clades between 2.3 and 6 million years ago [11], thus suggesting that Plasmodium is an ancient parasite of deer. Hence, co-evolution of both species could have made deer a well-adapted host for the parasite.…”

Malaria in Farmed Ungulates: an Exciting New System for Comparative Parasitology

“…This was, in some ways, not surprising, given that several species collected from other ungulate hosts had been described previously, but no additional work had been done on these parasites in over 30 years. One of these papers (3) detailed new instances of parasites that were morphologically consistent with Plasmodium odocoilei, a species described by Garnham and Kuttler in 1980 (4), from white-tailed deer. The type host had been splenectomized; thus, there was some doubt of the natural transmission of this parasite into deer hosts.…”

“…More important, though, was that these new samples had been collected at a time and using a method that enabled obtaining genetic data from ungulate parasites for the first time. Although originally described as being part of the genus Plasmodium , preliminary molecular systematic analyses described in each of these three papers showed them to be polyphyletic with respect to other Plasmodium species and, at least in some of the phylogenies, most closely related to parasites in the genus Polychromophilus , known to infect insectivorous bats (3, 6). …”