I recently completed a medical parasitology course as part of my medical education. One of the diseases we discussed was leishmaniasis. Leishmaniasis is a zoonotic disease that is transferred to humans from reservoir hosts via the sand fly vector. The sand fly injects the promastigote form of the parasite, and the parasite invades white blood cells and proliferates as amastigotes.
The amastigotes erupt out of white blood cells and the Leishmania parasite can cause three different types of symptomatology: visceral, cuteanous, or muscocutaneous. Leishmania donovani causes visceral problems, specifically Kala-azar, an irregular fever accompanied with an enlarged spleen and/or liver, anemia, diarrhea, etc. ultimately to death. L. donovani is found more or less globally. There are two other types of cutaenous causing Leishmania spp., Leishmania major and Leishmania tropica. Both of which cause lesions to the skin and are found in the Old World but the latter causes dry ulcers and the former, wet, serious ulcers.
Leishmania braziliensis (L. selvática) causes muscutaenous lesions, and as the name suggests is a New World disease. This is the parasite behind Espundia or Uta leishmaniasis, a horribly disfiguring and painful disease where very destructive oral/nasal lesions develop after 3-20 years of infection. Sloths and tropical rodents are the reservoir hosts for the L. braziliensis parasite.
As I mentioned, I just finished this parasitology class and so the information has been fresh in my head. This morning as I was reading my RSS feeds, I noticed a new open access PLoS One paper on the discovery of 4 cases of leishmaniasis in ancient remains recovered from the archaeological cemetery of Coyo Oriente, in the desert of San Pedro de Atacama, Northern Chile. The paper is titled, “Ancient Leishmaniasis in a Highland Desert of Northern Chile,” and authored by Chilean, Canadian and U.S. researchers. Upon reading the abstract, I was immediately drawn in because the discovery of leishmaniasis in this arid desert gives insight to ancient traditions. Even though the remains are relatively new, about 1,000 years old, these come from a time period when the Americas were not contacted by Europeans and not much is known about these people.
The remains recovered yielded 4 individuals, all middle aged females (though sex determination was not made on pelvic bones), with massive bone destruction to the face. Other diseases such as osteocarinoma, leprosy, trepanosomiasis, Yaws disease, and tuberculosis can cause such lesions so the authors decided to screen the bone to find any genetic markers of the pathogen. Cloning and sequencing indicated that the researchers were looking at the handy work of the Leishmania parasite, but the sequence differs from Old World Leishmania spp. It could not be confirmed if it was modern Leishmania braziliensis (L. selvática), but looking from the osteological pathology… I’d guess it to be safe to assume these individuals were infected by L. braziliensis.
As indicated earlier this is a curious finding, because L. braziliensis needs tropical mammals, like the sloth, as a host. There have been no sloths in the 20 million year old rainless Atacama desert. This means that two situations could have happen,
“infected individuals could have been natives of San Pedro de Atacama who traveled to the endemic zone, were infected with Leishmaniasis and then returned to their native high altitude desert. Alternatively, they could have been natives of the distant endemic area who migrated to San Pedro de Atacama after they became infected. The long incubation period between infection and the development of destructive facial and boney lesions–up to 20 years —would have allowed plenty of time for infected travelers to complete their journey before they became debilitated.”
What we do know is the people of the Atacama desert, the Atacameños, and the people of the Yungas, in the Eastern Andes of Argentina exchanged of goods during this time period. The commerce presumably increased the amount of foreigners into the Atacama Desert leading to the possibility of patrilocality and intermarriage and kinship bonds between high altitude desert people and lowlanders from tropical areas. Considering that these 4 individuals are middle aged females it is very likely that they were foreigners who relocated, if not intermarried into Atacama culture, and were infected with leishmaniasis at an early age in their more tropical origins.
While there are a couple leaps of faith in this paper, the weak sexing of the individuals, and only one loci (LDR3) was sequenced to usable quality to diagnose a Leishmania infection, they no doubt had bony lesions — most likely leishmaniasis that did not originate in the Andean deserts but from tropical lowlands. At the very minimum this paper demonstrates people in pre-contact Chile had extensive trade networks, not only were they exchanging goods but also disease and possibly genes.
I really enjoy reading these sorts of papers when time permits, as they spark my interests both in medicine — in this case a form of ‘paleopathology’, anthropology and genetics. I suggest you have a read of this open access paper and let me know what you think of it… I’ve covered Andean archaelogical finds before but I am interested to know more about prehistoric Andean cultures. So if you got some to share about the Atacameños, Yungas, etc. please do.
- Costa, M., Matheson, C., Iachetta, L., Llagostera, A., & Appenzeller, O. (2009). Ancient Leishmaniasis in a Highland Desert of Northern Chile PLoS ONE, 4 (9) DOI: 10.1371/journal.pone.0006983