2011, Vol. 6 No. 2, Article 99

A Study on Prevalence and Pathological Effects
of Intestinal Helminths in Black Bengal Goat in Chittagong

Babu Kanti Nath, Krishna Roy, Amir Hossan Shaikat*, Subrata Kumar Shil and Md. Zohorul Islam

Chittagong Veterinary and Animal Sciences University,
Khulshi, Chittagong, Bangladesh

*Corresponding Author; e-mail address: [email protected]

ABSTRACT

Prevalence and pathological effects of intestinal helminths in Black Bengal goats were studied by examining 150 viscera collecting from three (3) slaughter houses of Chittagong district during raining and winter season over a period of 6 months .94.67% goats were infected with intestinal helminths. Species of helminth parasites identified included Oesophagostomum columbianum (92%), Trchuris ovis (56.66%), Moniezia spp (11.33%). Prevalence of intestinal helminth was significantly higher in winter (100%) than that in rainy (89.33%). Calculated odds ratio between winter and rainy was 18, which indicated that Black Bengal goats were 18 times more susceptible to helminth infection in winter. Pathological lesions were observed in case of O. columbianum, T. ovis and Moniezia spp. infection. In O. columbianum infection hard, raised, slightly yellowish to greenish colored nodules were observed. Microscopically it was characterized by catarrhal inflammation associated with destruction and desquamation of epithelial cells. But moderate infection with T. ovis was characterized by catarrhal inflammation along with the petechial haemorrhages on the intestinal mucosa where parasites were firmly attached. The study clearly suggests that Black Bengal goats are susceptible to intestinal helminths in both winter and summer seasons and most of the parasites recovered were associated with the production of variable degree of pathological lesions.

KEY WORDS

Prevalence, pathological effects, intestinal helminths, black bengal goat.

INTRODUCTION

In Bangladesh, the goat population stands at about 34.5 millions (FAO, 2003) of which 97.90% are distributed in rural areas and 2.10% in urban areas (BBS, 1986). The hot and humid climatic conditions of the country are highly conductive for the development and multiplication of parasites. Black Bangal goats usually harbor parasitic Infestations (Qadir, 1967; Haq and Shaikh, 1968) that affect livestock development in the country (Jabber and Green, 1983). Anorexia and reduced feed intake coupled with the direct effect of the parasites on the host contribute to reduce weight gain and lowered production (Soulsby, 1982).
A number of different studies carried out in different parts of the country revealed that parasitic infestations are rampant in livestock (Saifuzzaman, 1996). Very little attention has been paid to determine seasonal prevalence and to study the pathological conditions produced by intestinal helminths in Black Bengal goats in Chittagong.
The present study was therefore undertaken to study prevalence, population dynamics, effects of seasons on the prevalence of intestinal helminths in Black Bengal goats in Chittagong and pathological effects produced by them.

MATERIALS AND METHODS

The investigation was carried out in Chittagong district during rainy and winter seasons over a period of 6 months. 150 viscera of Black Bengal goats were collecting from three (3) slaughter houses located at Oxygen, Firinghi Bazar and Jhawtola of Chittagong district immediately after slaughter, The intestines were carried to the laboratory in polythene bags and examined carefully from the parietal surface to detect the gross pathological changes. The intestine was cut along the log axis with the help of scissors to facilitate thorough examination of the internal mucus membranes . Parasites were collected according to the procedures by Urquhart et al. (1996) and washed several times in normal saline. Nematodes were preserved in luke-warm 70% alcohol . Trematodes and cestodes were preserved in 10% formalin. Nematodes were identified by preparing temporary slides and Cestodes and trematodes by preparing permanent slides (Cable, 1957) using the keys and descriptions of Soulsby (1982). Gross pathological lesions were observed carefully and recorded.

RESULTS AND DISCUSSION

Prevalence
Prevalence of gastrointestinal helminths in Black Bengal goat was recorded as 94.67% (Table 1) which was higher than the rate of infection of reported earlier by Hassan (1964) and reported by Patel et al. (2001) who recorded 82.1% and 54.92% prevalence of helminth infestations in goats in India .The variation between the present and earlier results might be due to the differences among the geographical locations and climatic conditions of the experimental areas, method of study, sample size, breed of the animals. Bangladesh is a tropical country with hot-humid environment. Here most of the goats are reared in rural areas in scavenging or semi scavenging system (Devendra, 1970). In this type of rearing, goats graze on the fields. Probably, this type of practice plays a vital role in the high rate of parasitic infestation.
Prevalence of O. columbianum (92%) was the highest and that of Monieza spp. (10.66%) was the lowest (Table 1). Hassan (1964) reported that 92.7% goats were positive for Oesophagostomum spp. and 10.9% for Moniezia spp. infestation. Qadir (1967) and Haq and Shaikh (1968) also recorded the high prevalence of O. columbianum in goats in Mymensingh district throughout the year. The cause of higher prevalence of O. columbianum can be attributed to bionomics of this parasite The parasite is found in abundant on the grass blades especially during the morning and in the evening hours (Soulsby, 1982). Goats are habitual of eating grass from the top level (Devendra, 1970). Therefore, chance of gaining infection with O. columbianum remains very high. Lower rate of infestation with Moniezia spp observed during present studies may be due to the fact that the viscera collected from the slaughterhouse were mostly of adult goats where as infection with Moniezia spp. usually occurs in young goats (Soulsby, 1982).
Prevalence of T. ovis was 56.66% in Black Bengal Goats. In case of T. ovis, infective stage is egg containing first stage larva (Soulsby, 1982), and goats become infected by the ingestion of infective eggs during grazing. In this case, infective eggs are not capable of active movement. So, they remain at the level of grass root (soil). So, chance of infection in browser goats with T. ovis remains logically relatively lower than that of the O. columbianum.
Prevalence of O. columbianum was higher in the winter (100%) than the rainy (84%) season (Table 2). In tropical and subtropical areas, in O. columbianum infections, the prolonged survival of the L4 within the nodules in the gut wall and the lack of an effective immunity made control difficult until the advent of effective anthelmintics (Urquhart et al.1996). Prevalence of T. ovis was higher in the winter (54%) than the rainy (42.6%) season (Table 2). On the other hand Prevalence of Moniezia spp.was also higher in winter (17.3%) than the rainy (5.33%) season. Moniezia spp. infestation is common in kids during their first year of life and less common in older animals. A seasonal fluctuation in the incidence of Moniezia spp. infestation can apparently be related to active periods of the forage mite vectors during the summer in temperate areas. The cysticercoids can overwinter in the mites. (Urquhart et al., 1996).
Prevalence of gastrointestinal helminths identified during present study was relatively higher in winter than that in the rainy (Table 2). Almost Similar trend was observed by by Asanji and Williams (1987) in Africa. In Bangladesh, winter usually begins with mild cold and passes through moderate cold and temperature ranging from 18.03º-23.66º C. This climatic condition is suitable for the development and survival of many geo-parasites like Oesophagostomum spp., Trichuris spp. etc. Arthropod vectors like oribatid mites (which transmit Moniezia spp.), which live on the pasture, are more available in winter than summer (Urquhart et al., 1996). Probably for these reasons, prevalence of such type of helminth parasites was relatively higher in winter.
Pathological lesions in helminthiasis
O. columbianum
Grossly, nodule formation was commonly observed in O. columbianum infestation. Nodules were hard, raised, slightly yellowish to green in color measuring 0.25X0.50 cm in size (Fig 1). The findings were in conformity with the observations of Lapage (1962), Soulsby (1965) and Smith et al. (1992). Histologically the lesions were characterized by the infiltration of large numbers of eosinophils, lymphocytes, macrophages and formation of foreign body giant cells. Thangathurai and Rao (2002), Powers (1961), Soulsby (1965) and Mondal and Islam (1994) reported destruction and desquamation of epithelial cells of intestinal wall associated with the hyperplasia of the goblet cells and infiltration of plasma cells in Oesophagostomum infestation.
T. ovis
Most infections caused by T. ovis are light and asymptomatic. In some cases a large numbers of worms cause a diptheritic inflammation of the caecal mucosa. This results from the subepithelial location and continuous movement of the anterior end to the whipworm as it searches for blood and fluid. In Trchuris infestation, slight catarrhal inflammation was observed with Petechial haemorrhages on the mucosa, infiltration of lymphocytes, eosinophils and macrophages on the caecum and colon and proliferation of goblet cells. These observations were in line with findings of Kumar and Lal (1987) and Saha and Bhowmik (1998). T. ovis penetrates the intestinal wall by their anterior parts. Probably during the process of penetration, they cause mild to moderate degree of damage in the intestinal surface, resulting petecheal haemorrhages. Continuous irritation of the intestinal wall by the adult parasites results into catarrhal inflammation and increase in numbers and size goblet cells (Soulsby, 1965). In trichurosis, lymphoid nodules on the lamina propria were enlarged from which suggests that the parasite may be producing some chemical mediators that cause lymphoid proliferation locally.
Moniezia spp.
During the present study, no considerable pathological changes were detected in Moniezia spp. infestation. Heavy infestations may cause unthriftiness, diarrhea and even intestinal obstruction. However, Moniezia infections are so obvious, both in life, because of the presence of proglottids in the faeces, and at necropsy, that other causes of ill health may be overlooked (Urquhart et al., 1996)
Conclusion
The study clearly suggests that Black Bengal goats are susceptible to intestinal helminths in both winter and rainy seasons and most of the parasites recovered are associated with the production of variable degree of pathological lesions. Gastro-intestinal parasitic infestation may be the major cause of stunted growth of Black Bengal goat resulting heavy economic loss. Animals should be dewormed at regular interval with an appropriate anthelmintic. Management system and overall hygiene conditions should be improved for better growth and overall production performance of Black Bengal goat.

ACKNOWLEDGEMENTS

The author deeply acknowledges the support and cooperation extended by Department of Pathology and Parasitology for conducting this study successfully.

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TAbles

Table-1. Prevalence and population dynamics of intestinal helminth parasites in Black Bengal goats.

Table-2. Prevalence of helminth parasites in Black Bengal goat in rainy and winter seasons

FIGURES

Fig. 1: Nodular lesions on the intestinal wall due to O. columbianum infection.