Case Report on Scabies Infection in Bwindi Gorillas

Uganda Wildlife Authority (UWA) and the International Gorilla Conservation Programme (IGCP) have been working together to treat a skin disease in one of the gorilla groups in Bwindi Impenetrable National Park. This case has involved both veterinarians and park managers in the attempt to decipher the cause of the problem and to treat it, while at the same time preventing spread to other gorilla groups, and discovering how the infection was introduced into the gorilla group if not naturally present in the population.
In August one member of the Katendegere Group was reported to have small patches of hair loss. At the time, the park and IGCP staff were not overly concerned as gorillas can have bald patches as results of scrapes or wounds, among other causes. However, this condition progressed and by the end of August, a vet check by the IGCP veterinarian and park staff showed that both young animals in the group had more significant hair loss. The young subadult male, Kasigasi - 6 years old - had patches of hair loss visible over his abdomen and on the back of his legs. The youngest animal in the group, an 8 month old infant male, showed more serious hair loss. Dr. Gladys Kalema, the Veterinary Officer for Uganda Wildlife Authority in Kampala was contacted and she immediately travelled down to Bwindi with Dr. Richard Kock, a visiting wildlife veterinarian from Kenya Wildlife Services.
Kasigasi was darted and immobilised for diagnosis and treatment. On close-up examination his condition was much more severe than it appeared from a distance. He was covered with skin lesions consistent with scabies infection (Sarcoptes scabiei). Samples were taken for laboratory diagnosis, and he was treated for scabies and bacterial infection. The Makerere University Veterinary laboratory examined the samples and confirmed the diagnosis of scabies.
Sarcoptes scabei is a mite that infests the skin of many animal species, including primates. Domestic animals commonly are affected, and in dogs it causes one type of the common skin disease known as mange. Humans can also have scabies, and it is common in communities around the park. Scabies is very infectious and direct contact with an infected animal or person is not required for transmission.
Although the vet team was extremely interested in the source of infection, the priority action was to treat all the animals in the group and to examine other gorilla groups for signs of infection. Luckily the Katendegere group appears to be the only group with clinical signs, so it is assumed that other groups are not affected. The follow-up to the diagnosis of scabies has included darting all of the other animals in the group. The adult animals in the group, one silverback and one female, showed little if no symptoms and have simply required treatment by remote injection via a dart gun. However, the adult female was carrying the small infant who was becoming increasingly bald and weakened by the infection. An infant of this young age of 8 months is still carried and protected by his mother, who in this case is a very shy female, often difficult to see in the best of circumstances. The infant was too small to treat simply with a dart fired from a distance, so the team attempted to dart and immobilise the mother in order to hand-grab the infant for treatment.
The difficulties of working in the "Impenetrable" forest became painfully clear during attempts to save the infant gorilla. The female was extremely nervous and she hid in the deepest bush whenever the vet team approached. In addition, the silverback continually placed himself between the female and the team, precluding any attempt at darting. The brief views of the infant showed him to be very thin and almost completely bald, leading to the conclusion that he was likely to die. This prediction proved sadly true as the emaciated body of the little baby gorilla was found near the group's nests one morning.
Gorilla females normally carry their dead infants for a number of days before dropping the body and the fact that this one was left the first morning after his death might suggest that he had been weak and immobile for a period such that the female had already begun to lose maternal attachment towards him.
This was a very sad outcome for a team of rangers and vets who had tried a number of times to save this little gorilla. Additional samples taken at the autopsy of the infant male confirmed the diagnosis of scabies.
The immobilisation of Kasigasi marks the first time a Bwindi gorilla has been darted, so there is no historical data on presence or absence of scabies in this population. However, the nearby Virunga population has a long history of gorilla immobilisations for emergency treatment, and scabies has not yet been reported. Therefore this diagnosis is the first known case of scabies in a wild mountain gorilla. This is cause for concern about the source of infection, and a sample has been sent to an entomologist to attempt to identify if the mite is of human or animal origin. If it is possible to identify the source, it will help park managers narrow down the list of possible management actions to take. For example, if the source is domestic animals, stricter controls of animals herded along public paths through the park might be considered. Alternatively if the source is human, the park must consider all the possible means for infection from humans including the different activities that bring people into the park, both legally and occasionally illegally. From the local people's perspective, the gorillas also range outside of the park in a similar "illegal" fashion to raid banana tree plantations and this is another potential source of infection from both humans and domestic animals.
The park and IGCP are continuing efforts to prevent re-infection of these or other gorillas in Bwindi.

Liz Macfie (from: IGCP Update 2, September 1996)

Dr. Liz Macfie was the Director of the Volcano Veterinary Centre in Rwanda from 1989 to 1992, and since 1992 she has been the Project Manager for the IGCP in Uganda. This program started working in Bwindi and has gradually expanded operations into Mgahinga since the end of 1995.

Additional information: The silverback leader of the Katendegere group died from old age in May 1996. Following his death, a blackback left the group. Currently, the group is led by a young silverback who has a broken wrist, but this does not hamper him severely.
The group has only three members now, and the tourist visits are being restricted. Only four tourists are permitted per day. No further advance bookings are made by UWA. Any permits not sold in Kampala are sold in Buhoma on the stand-by basis. IGCP and UWA have just started to habituate another group, but it will take 1-2 years until it can be visited by tourists.

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