Document Details
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Document Type |
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Article In Journal |
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Document Title |
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Comparative Studies on the Susceptible and Non-Susceptible Biomphalaria alexandrina دراسات مقارنة على بيومفلاريا الإسكندرية للإصابة وغير الحساس لل |
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Subject |
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Comparative Studies on the Susceptible and Non-Susceptible Biomphalaria alexandrina |
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Document Language |
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English |
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Abstract |
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Abstract: Schistosomiasis is an important parasitic disease that infects humans. Among the main species of
schistosomes infecting humans is Schistosoma mansoni and S. haematobium. Snails of various genera, such
as Biomphalaria alexandrina and Bulinus truncates, act as intermediate hosts and play a major role in the
transmission of schistosomes. Transmission from human to snail is under the influence of the ciliated
miracidium larvae that hatch from the eggs of the parasite voided in the faeces or urine. After a period of asexual
multiplication in the snail, a second aquatic larval stage, the cercaria, emerges and infects human by direct
penetration of the skin. The present work was carried out on Biomphalaria alexandrina snails, the intermediate
host of Schistosoma mansoni. Snails were collected from various sites in south western Saudi Arabia. Their
progeny were reared in the laboratory under standard conditions. Different biological experiments were carried
out to determine the susceptibility level in the various populations of snail. The miracidia were obtained by
isolating viable ova of the hatching parasite from faeces of infected individuals (human and mice). Different sets
of regulated experimental infection of snails with the miracidia of Schistosoma mansoni were preformed. The
effect of miracidial density, water temperature, miracidial age, size of snails, as well as light and darkness were
investigated. The study revealed that the infection rate increased as the number of miracidia used increased
(1, 60%; 2, 60%; 3, 70%; 5, 80%; 15, 90%; and 20, 90%). No significant increase of infection rate was achieved
at higher water temperatures (at 15°C: 65% with newly hatched miracidia; 75%, with 15 minutes miracidia;
85% with 30 minutes miracidia; 95% with 45 minutes miracidia and 100% with 60minutes miracidia. At 20°C: 75%
with newly hatched miracidia; 80%, with 15 minutes miracidia; 90%, with 30 minutes miracidia; 95% with
45 minutes miracidia and 100% with 60 minutes miracidia). Similar results were obtained at 25°C and 30°C.
However, the infection rate decreased in relation to snail size increase. At snail size 2-4 mm the infection rate
was 90%, the rate decreased to 85% at 4-6 mm and 6-8 mm size, while at 8-10 mm size the rate was 80%. At 10-12
mm and 13-15 mm size the rate dropped to 75%. Light and dark conditions had a significant difference on the
infection rate (40% in darkness and 90% in light). Laboratory observations also indicated that some of the snails
exposed to infection with miracidia of the respective parasite developed infection and produced cercariae, while
the rest remained uninfected. |
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ISSN |
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1817-3055 |
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Journal Name |
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World Journal of Medical Sciences |
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Volume |
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2 |
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Issue Number |
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2 |
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Publishing Year |
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1427 AH
2007 AD |
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Article Type |
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Article |
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Added Date |
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Tuesday, March 5, 2013 |
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Researchers
| منال بكر جمجوم | Jamjoom, Manal Bakr | Investigator | Doctorate | mjamjoom@kau.edu.sa |
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