Parasitology

Research Article

Intestinal schistosomiasis in chimpanzees on Ngamba Island, Uganda: observations on liver fibrosis, schistosome genetic diversity and praziquantel treatment

C. J. STANDLEYa1, L. MUGISHAa2a3, M. ADRIKOa4, M. ARINAITWEa4, J. RUKUNDOa5, L. AJAROVAa5, S. MOPYAa4a6, M. BETSONa7, N. B. KABATEREINEa4 and J. R. STOTHARDa7 c1

a1 Ecology & Evolutionary Biology, Princeton University, Princeton, New Jersey 08544, USA

a2 College of Veterinary Medicine, Animal Resources and Biosecurity, Makerere University, P.O. Box 7062, Kampala, Uganda

a3 Conservation & Ecosystem Health Alliance (CEHA), P.O. Box 34153, Kampala, Uganda

a4 Vector Control Division, Ministry of Health, P.O. Box 1661, Kampala, Uganda

a5 Chimpanzee Sanctuary and Wildlife Conservation Trust (CSWCT), Entebbe, Uganda

a6 Department of Radiology, Mulago Hospital, P.O. Box 7051, Kampala, Uganda

a7 Disease Control Strategy Group, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK

SUMMARY

Despite treatment with praziquantel (PZQ) at 40 mg/kg in food, several chimpanzees on Ngamba Island Chimpanzee Sanctuary (NICS) continue to excrete eggs of Schistosoma mansoni. To monitor disease, 8 animals were closely examined under anaesthesia in March 2011 with portable ultrasonography and by rectal snip biopsy. Schistosome genetic diversity had been previously assayed within 4 of these chimpanzees, finding extensive diversity with 27 DNA barcodes encountered, although none was common to all animals. Calcified schistosome eggs were found in the rectal snips from 5 chimpanzees and liver fibrosis was clearly documented, indicative of progressive disease in 6 animals, the latter being surprisingly advanced in a younger chimpanzee. All 8 animals were treated under anaesthesia by oral gavage with PZQ at 60 mg/kg dosing that was well tolerated. These animals were again re-examined in June 2012 using stool and urine sampling. Only 1 chimpanzee appeared to be free from infection and active egg excretion was confirmed in 6 animals. If intestinal schistosomiasis is to be controlled within this setting, a long-term disease management plan is required which should combine active case-detection with an insistent treatment regime with praziquantel for these chimpanzees, exploring perhaps the performance of even higher dosing.

(Received May 03 2012)

(Revised August 28 2012)

(Revised August 30 2012)

(Accepted August 30 2012)

(Online publication October 25 2012)

Key words

  • Schistosoma mansoni ;
  • Pan troglodytes ;
  • morbidity;
  • ultrasonography;
  • DNA barcoding

Correspondence:

c1 Corresponding author: Disease Control Strategy Group, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK. E-mail: jrstoth@liverpool.ac.uk.

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