Atypical human trypanosomiasis: a neglected disease or just an unlucky accident?

Importance of Nonenteric Protozoan Infections in Immunocompromised People

“…Due to the coevolution of humans alongside the endemic trypanosomes of Africa, humans and some primates have evolved a non-immune-mediated mechanism designed to specifically eliminate African trypanosomes (365,423,424). The human serum components involved in the specific lysis of trypanosomes are referred to as human trypanolytic factor (HTLF) (424).…”

“…However, recent reports suggest that certain subtypes of non-human-infecting trypanosomes may also be resistant to HTLF (285,365,416). It is plausible that this resistance to HTLF has enabled some human infections with non-human-infecting trypanosomes to occur.…”

“…This is probably due to the comparatively recent arrival of humans in the Americas approximately 9,000 years ago (365).…”

“…Trypanosoma lewisi is a member of the subgenus Herpetosoma, which includes several species of trypanosomes that are usually obligate parasites of rodents (298,365). Trypanosoma lewisi infection is transmitted by various species of flea and has a worldwide distribution (298,365).…”

“…Members of the subgenus Herpetosoma are morphologically indistinguishable from each other and are often described collectively as T. lewisi-like organisms (298). In rodents, T. lewisi-like infections are thought to be nonpathogenic and self-limiting due to the organism's limited capacity to alter its surface coat (298,365). In humans, however, T. lewisi-like organisms have been reported to cause a transient disease characterized by fever, anemia, anorexia (285,299,495), and, in some cases, generalized edema (285).…”