Lethal effect of high temperatures on the eggs of Fasciola hepatica

Document Type: Short paper

Authors

1 Department of Pathobiology, School of Veterinary Medicine, Shiraz University, Shiraz, Iran

2 Department of Food Hygiene and Public Health, School of Veterinary Medicine, Shiraz University, Shiraz, Iran

3 Graduated from School of Veterinary Medicine, Shiraz University, Shiraz, Iran

4 BSc in Veterinary Medicine Lab. Technology, Department of Pathobiology, School of Veterinary Medicine, Shiraz University, Shiraz, Iran

Abstract

Fasciolosis is a cosmopolitan parasitic disease with considerable economic and public health importance.
Fasciola hepaticais the major cause of fasciolosis in man and domestic animals. Although remarkable
research works have been done around the optimum temperature and time required for miracidial
development, little is known aboutthe exact susceptibility of Fasciola hepaticaeggs to high temperatures. In
the present study, Fasciola hepaticaeggs were initially incubated at 40°C, 45°C, and 50°C for various times
(1, 2, 3, 4 and 5 h), followed by incubation at 28°C for 16 days. Miracidial formation was subsequently
investigated on the 16th day of incubation. Even though the rate of miracidial formation in the control group
was 52%, in the eggs incubated at 40°C for 1, 3, and 5 h, the miracidial formations were 51.4%, 42.4% and
39.9%, respectively, and these values in the group incubated at 45°C were 46%, 42.5% and 33.7%, as well.
However, in the case of incubation at 50°C for 1, 2, 3, 4 and 5 h, these values were recorded as 1.96%,
0.57%, 0.07%, 0.00% and 0.00%, respectively. The results indicated that the eggs were susceptible to high
temperatures and incubation of the eggs at 50°C for 4 h was enough to significantly inactivate the eggs and
prevent miracidial formation (P<0.001). However, using the livestock faeces as fertilizer in many rural areas
may lead to the contamination of pasture. According to the findings of this study, in the areas with a high
prevalence rate of Fasciola hepatica, manure storage for a sufficient time or heating the livestock manure
before use as fertilizer is strongly recommended.

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