Occurrence of Cyptosporidium Oocysts in a Natural Population of Non-Human primates in Sri Lanka
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Date
2001-11-16
Authors
Ekanayake, D. K.
Horadagoda, N. U.
Sanjeevani, G. K. M.
Arulkanthan, A.
Dittus, W. P. J.
Journal Title
Journal ISSN
Volume Title
Publisher
University of Peradeniya, Peradeniya, Sri Lanka
Abstract
Cryptosporidium is an enteric protozoan parasite responsible for diarrhoea in children,
young animals and immunocompromised hosts. In Sri Lanka, the infection has been reported in
man and a wide variety of domestic animals. The objective of the present work was to
determine the occurrence of the infection in a natural population of monkeys and the
association of the infection with the habitat.
The study was conducted in nonhuman primates (infants to adults) that habituated
separate locations in the natural sanctuary of the Polonnaruwa archaeological reserve, which
bordered a human habituated area. Faecal samples were collected from 117 monkeys
comprising 81 toque monkeys (Macaca sinica), 21 gray langurs (Semnopithicus entellus) and
15 purple-faced langurs (Trachypithecus senex). The samples were examined for
cryptosporidium oocysts using Sheather's sucrose floatation method followed by staining with
the modified Ziehl Neelsen technique. The oocysts were also measured using an ocular
micrometer and selected positive samples were stained with Nigrosin, Giemsa and modified
trichrome to verify the identification of the parasite. In addition, the oocysts were quantified as
described by Noordeen et al (Veterinary Parasitology: 2000: 93; 95-101).
The identification of the parasite was based on staining characteristics and micrometry
(2-6 urn). Of the 117 specimens examined, 28.2 % (33/117) were positive for cryptosporidium
oocysts. An overwhelming proportion of the infected animals (97 %) were from home ranges,
which overlapped with human habituated areas as compared with non-human habituated areas
(3 %). The prevalence of the infection varied between the species of monkeys with gray
langurs having the highest prevalence (38.1 %) followed by toque monkeys (30.9 %); none of
the purple-faced langurs were positive for cryptosporidium oocysts. Twenty seven percent of
the infected animals had a low oocyst counts (1 - 999 oocysts per gram of faeces), 51 % had
moderate counts (1000 - 4999) while 18 % had high counts (>5000). The mean oocyst count of
cryptosporidium positive samples was 3633 (166 - 34,250). Except for one juvenile toque
monkey that had mild diarrhoea with a high oocyst count (34,250), all cryptosporidium
positive animals were asymptomatic.
This is the first study to examine the occurrence of cryptosporidium in nonhuman
primates in Sri Lanka. The presence of the infection in the three species of monkeys studied
was closely related to their habitat. Despite the variation in the oocyst counts, a majority of the
infected animals were asymptomatic suggesting that an ecological balance exists between the
hosts and the parasite in the study area.
Description
Keywords
Veterinary , Oocysts , Population , Primates
Citation
Proceedings & abstracts of the Annual Research Sessions 2001,University of Peradeniya, Peradeniya, Sri Lanka,pp.164