3 July 2020
This is part of a student blog series as part of the University of Pittsburgh’s Disease Ecology Class that our own Shane M Hanlon is currently teaching. Find out more about the series and read all the posts here!
By Anna Bryant
Wild giraffes across Africa are suffering from multiple skin disorders. The Rothschild’s giraffes (Giraffa camelopardalis rothschild) population is shrinking at an alarming rate in Kenya and Uganda. Located in Uganda, Murchison Falls National Park (MFNP) did a survey in 2016 that discovered that one third of their giraffes had rash-like lesions of unknown origin. The International Union for the Conservation of Nature regarded this disease as a major threat. Because Rothschild’s giraffes are a threatened species and their range is decreasing, it is important to study any disease process that threatens their health.
They referred to this condition as the “giraffe skin disease” that has affected the wild giraffes throughout Africa. There have been findings of parasitic skin diseases in other areas of Africa including an unidentified spirurid nematode in Tanzania on a Masai giraffe, and filarial worms (Filaroidea) in Rothschild’s giraffes in other areas of Uganda. In addition, there have been reports of similar lesions caused by Stephanofilaria parasites in white and black rhinoceros in Kenya, hippopotamus in South African and pigs in the Democratic Republic of Congo.
At Murchison Falls National Park (MFNP), the Uganda Wildlife Authority gathered seven adult Rothschild’s giraffes, immobilized them and sampled their skin lesions. In all seven of these giraffes, they found adult nematodes in the deep part of the dermis or in the follicular epidermis. These adult nematodes were 120-150 micrometers thick. Then for further identification, samples of dry skin scrapes were sent to a pathology lab at the Smithsonian in Washington, DC. All seven samples had severe, chronic, regionally extensive, eosinophilic dermatitis with adult or larval microfilaria nematodes. In addition, genomic study on four skin scrapes was done at the Smithsonian Center for Conservation Genomics. All four skin scrapes contained filarial sequences of different lengths and quality. However, they did not find any sequence matching the 460 base pair length with > 92% confidence in GenBank.
The following year, four skin-diseased Rothschild’s giraffes were rounded up, immobilized and given a subcutaneous injection of ivermectin, an anti-parasitic drug used to treat roundworm, threadworms and other parasites. Ivermectin was discovered in the 1970’s and was initially used as a veterinary drug for killing parasites in commercial livestock, pets, and horses. Soon it was learned that ivermectin could be used in humans for treating disfiguring parasitic diseases infecting people in the tropics. The drug has been called a “Wonder Drug” for curing both Onchocerciasis and Lymphatic filariasis in millions of people living in poor, disadvantaged conditions. Could it do the same for Rothschild’s giraffes? The skin lesions on the four injected giraffes disappeared within 4 months!
There are only 1,400 individual Rothschild’s giraffes remaining. With the increase in habitat loss, poaching and the decrease in giraffe population, it is important to study any infectious disease they have so it can be properly managed and treated. Even though the parasitic skin lesions were not life threatening, secondary bacterial infections in these lesions could lead to more dangerous conditions, and possibly cause a giraffe to be more susceptible to attacks by predators. This shows the need to monitor threatened populations for even sublethal diseases that might lead to something more serious.
Whittier, C. A., Murray, S., Holder, K., McGraw, S., Fleischer, R., Cortes-Rodriguez, N., … & Atimnedi, P. (2020). Cutaneous Filariasis in Free-Ranging Rothschild’s Giraffes (Giraffa camelopardalis rothschildi) in Uganda. Journal of Wildlife Diseases, 56(1), 234-238.
Crump, A., & Omura, S. (2011). Ivermectin, “wonder drug” from Japan: the human use perspective. Proceedings of the Japan Academy, Series B, 87(2), 13-28.