Studies on the prevalence and biology of Blastocystis spp. isolated from zoonotic reservoirs in Malaysia / Farah Haziqah Meor Termizi
Blastocystis is a highly prevalent protozoan parasite of the intestinal tract of a wide range of animal hosts, including humans. To date, very little information is available of parasite in zoonotic potential reservoirs namely, companion animals, household pests and poultry population. The sugges...
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| Format: | Thesis |
| Published: |
2017
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| Online Access: | http://studentsrepo.um.edu.my/7660/1/All.pdf http://studentsrepo.um.edu.my/7660/9/haziqah.pdf http://studentsrepo.um.edu.my/7660/ |
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| Summary: | Blastocystis is a highly prevalent protozoan parasite of the intestinal tract of a wide
range of animal hosts, including humans. To date, very little information is available of
parasite in zoonotic potential reservoirs namely, companion animals, household pests
and poultry population. The suggestion that the intimate association between humans
and animals could facilitate transmission led us to investigate Blastocystis in several
animal hosts in the domestic environment such as cats, dogs, rodents, cockroaches,
house geckos and chickens as no data is available to date. From October 2012 until
April 2015, a total of 938 intestinal contents and/or faecal samples from different hosts
were collected from three states of Peninsular Malaysia namely; Kuala Lumpur,
Selangor and Perak. The prevalence of Blastocystis infection was investigated by
screening and in vitro cultivation method using Jones medium supplemented with 10%
horse serum. A total of 26.3% (47/179) chicken faecal samples screened were positive
for Blastocystis infection with high prevalence in free-range species compared to barnreared
chicken. Results from this first epidemiological study showed positive infection
in broiler chicken despite reared in farming method least prone to contamination.
Intestinal infections were equally high 45.4% (133/293) in wild rats and cockroaches
40.4% (61/151) particularly the nymph stage. All infections were observed
asymptomatic. Surprisingly, house geckos were free from infection. Light microscopy
examination between the animal isolates was almost similar in morphology to B.
hominis with the exception for their considerable size variations (chicken isolates: 10 to
100 μm; wild rat isolate: 4 to 45 μm; cockroach isolate 9 to 15 μm in diameter).
Furthermore, ultrastructure examination demonstrated surface coat thickness and
electron density also varied between different isolates. Close to half of the chicken
isolates were completely electron-lucent when examined under the transmission
electron micrographs whereas electron dense areas were observed in the central vacuole of the wild rat and cockroach isolate which indicated lipid accumulation. Surface coat
were present on all isolates with the cockroach isolates the thickest between 276.17 to
336.67 nm followed by chicken isolates (239.39 to 169.27 nm) and the least in wild rat
isolates (135.51 to 196.82 nm). Using the sequenced-tagged site (STS) primers and
DNA barcoding method, four subtypes were detected from chicken isolates namely,
ST1, ST6, ST7 and ST8. Meanwhile, four subtypes were detected from wild rats with
ST1, ST4, ST5 and ST7. In cockroach population, two cockroach isolates were
identified as ST3 and one isolate was closely related to allele 114 which is most likely
to be the new subtype. Although cultivation was unsuccessful from all cat and dog
samples, 12 cat samples were found positive for Blastocystis sp. ST1. The finding of
this study adds to our understanding of the biology, transmission as well as distribution
of this organism in animals living in close association to humans and highlights their
zoonotic potential. |
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