Saadullah Jan

Serodiagnosis, Epidemiology And Economic Improtance Of Hypodermosis In Goats In Balochistan - 2013

Hypodermosis is an endemic infestation of cattle and goats in Pakistan. It is caused by H. lineatum and H. bovis in cattle and P. silenus in goats and is commonly existed species in Pakistan which belong to order Diptera, family Oestridae. The larvae of these flies are obligatory parasites of their hosts and are economically very important causing severe damage to the skins/hides effecting leather industry. Goat warble fly infestation has severe economic impact on tanning industries and it also causes growth retardation, carcass depreciation and production losses of milk and meat. Keeping in view the importance of this infestation, studies were designed on serodiagnosis, epidemiology and economic importance of hypodermosis in goats in northern uplands of Balochistan, Pakistan, with the objectives to diagnose warble fly infestation at early stages through serology for better control and eradication strategies, to study different epidemiological factors (age, sex, breed, temperature, humidity and rain fall) contributing goat warble fly infestation in the study areas, to compare seroprevalance over the prevalence based on clinical examination and to study the economic importance of hypodermosis in Loralai, Ziarat and Pishin districts of Balochistan, Pakistan. The duration of the study was one year commenced from April 2011 to March 2012. The most prevalent breed of goat i.e. khurasani breed in uplands of Balochistan was involved in the study which was compared with the Non-descriptive breed of goats. It is expected that the result of this study will be helpful to plan better control and eradication measures of warble fly by providing the base line data for further improvement in livestock sector in Balochistan.
Serological studies for an early diagnosis and seroprevalence of hypodermosis were carried out by commercial ELISA kit (IDEXX hypodermosis serum antibody test) method. A total of 1440 blood samples were collected during the study. Sera were separated and stored at - 20 °C until further use. The infestation was detected in May and June (summer) where as the infestation is usually detected clinically in the months of October until February (winter) when warbles appear on the back and flank regions of the animals. ELISA based seroprevalence showed the highest mean percentage (48.45 %) of goat warble fly infestation in all the three districts, while the mean percentage by clinical palpation method was 15.94 % in all the three districts. In the slaughter house and skin market studies the mean percentages of goat hypodermosis were 9.07 % and 7.16 %, respectively.
In the study of epidemiology, a total of 8640 number (2880 number per district) of goats of different age, sex and breed were examined on monthly bases by hand palpation clinico-parasitological method for the presence and prevalence of hypoderma infestation in the field animals. The mean prevalence percentage was 15.94 % i.e. 10%, 21.25% and 16.59% in Loralai, Ziarat and Pishin districts, respectively. In the study conducted in slaughter houses of all the three districts, a total of 4320 number (1440 number per district, 120 animals per month per district) of goats of different age, sex and breed were examined and the prevalence was recorded. Three age groups were selected for both the studies i.e. < 1year, 1-2 year and > 2 year old. The larvae were collected from naturally infested animals for identification. The mean prevalence percentage of hypodermosis in the slaughtered animals was 9.07 % i.e. 4.86%, 12.56% and 9.79% in Loralai, Ziarat and Pishin districts, respectively. Analysis of data by Pearson Chi-square test (?2) revealed highly significant difference (P<0.05) in the overall prevalence of hypodermosis district-wise in the fields and slaughter houses. Results were processed using Microsoft Excel 2007. In comparison of the fields and slaughter houses, the prevalence was significantly higher in the field animals as compared with the slaughterhouse animals in all the districts. In the study based on examination of the infested skin in the skin markets, a total of 3600 numbers of skins of goats (1200 numbers per district, 100 skins per month regardless of age, sex and breed) were examined by making monthly visits to the skin markets of each district. The intensity of the infection was also recorded by counting the number of holes in each infected skin. The overall district-wise mean prevalence percentage was 7.16 % and the mean intensity was 16.19 holes per skin. Analysis of data of the skin market by Pearson Chi-square test, using SPSS version 16, revealed highly significant differences (P< 0.05) in the prevalence of hypodermosis district-wise.
Month-wise prevalence in the field animals showed that the highest prevalence was during January and lowest during October in Loralai, Ziarat and Pishin districts. In the slaughter house study, highest prevalence was observed during October and the lowest during July in Loralai district, highest during January and the lowest during July in Ziarat district whereas the highest prevalence was during the month of November and the lowest during July in district Pishin. Month-wise analysis of data by Pearson Chi-square test, using SPSS version 16, revealed highly significant differences (P< 0.05) in the prevalence of hypodermosis both in the field as well as in the slaughter house studies. Age-wise prevalence in the field as well as in the slaughter house animals showed the highest prevalence in the age group of 1-2 years as compared to the age groups of < 1 year and > 2 years. Analysis of data by Pearson Chi-square test, using SPSS version 16, revealed highly significant differences (P< 0.05) in the prevalence of hypodermosis amongst age groups both in the field as well as in the slaughter house studies. No significant difference was observed sex-wise and breed-wise in both the studies of fields and slaughter houses of the study areas.
The life cycle pattern in naturally infested goats with warble fly was studied in the fields and slaughter houses of the study areas from April 2011 to March 2012. All the observations regarding the life cycle stages were recorded. First instars larvae (L1) were observed in subcutaneous tissues from mid of May to mid of July in slaughter houses of the study areas. Second instars larvae (L2) were observed in the slaughter houses from mid of July to November. Third instars larvae (L3), as well developed warbles on the back and flank regions of the goats, were palpated in the field animals and observed in the slaughter houses from December until the end of February. The pupal period was observed in early spring in the months from March to mid of April. No larvae were observed in the slaughter houses and fields of the study areas during this period while the adult fly activity season (Oviposition period) was observed in early summer from mid of April to mid of May.
The estimation of economic losses due to skin damages were determined by multiplying the estimated infested numbers of skins with the value of loss per skin. The overall losses due to warble fly infestation in the study areas were calculated as Pak. Rupees 7578625.49 (Pak. Rs 7.57 million = US$ 77530.69, US$ 1= Rs. 97.75) annually.
Based on the early detection studies, it is concluded and recommended that the best time for the treatment of goat warble fly infestation in uplands of Balochistan is in the months of June and July when first larval instars are still in migratory stage and not yet have reached their final sites on the back and flank regions of goats to cause damage to the skin, where as the farmers usually treat their animals against warble fly in the winter season when they observe the warbles on the backs of the animals but at that stage the larvae have damaged the skins of the animals.



Department of Parasitology
Phd. Thesis

1771,T


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