Epidemiology and economic impact of bovine brucellosis in Peninsular Malaysia

Bovine brucellosis is an important bacterial disease in cattle and other bovine species including bison, elk and buffalo and is mainly caused by the bacterium Brucellaabortus. Brucellosis is a zoonotic disease with serious economic impact to livestockindustry in both developed and developing countries. The present study was carried out to understand the epidemiology of bovine brucellosis in Peninsular Malaysia; to describe its occurrence and distribution, to evaluate spatial and temporal clusters pattern and distribution, to identify potential risk factors associated with bovine brucellosis, to assess economic impact of bovine brucellosis to farmers and costs of monitoring, control and eradication to government and finally to evaluate the effectiveness of culling policy of area-wise eradication program of brucellosis in Peninsular Malaysia. A retrospective examination of surveillance data between 2000 and 2008 was carried out to investigate the presence and occurrence of bovine brucellosis in Peninsular Malaysia. The findings showed that bovine brucellosis is widely distributed across the peninsula. The annual seroprevalence for the 9-year study period was 2.7% and 21.7% for individual animal and herd level prevalence respectively. The herd prevalence fluctuated but remained high within the period of the study while animal prevalence was comparatively low but has a more discerning trend over the study period. In the second study, data on the surveillance activities was aggregated into district level due to lack of farm coordinate and confidentiality of the farm centriole of the districts was used as the coordinate to run spatial and temporal cluster, the ArcGIS and Sat Scan softwares were used for the analysis. The result showed that bovine brucellosis clustered in both space and time and cluster pattern confirmed the earlier finding of similar trend. Three clusters were detected: the first cluster around the state of Pahang and part of Johor covering 5 districts with 68 km radius, the second cluster was situated in Kelantan covering large area of 230 km with 51 districts and the third cluster wa in Selangor affecting 6 districts covering 34 km. However, the cluster was not statistically significant. High risk areas (hot spot) were also detected to be around the clusters identified. A case-control study was conducted in four states of Peninsular Malaysia: Kelantan,Pahang, Negeri Sembilan and Selangor whereby 71 farmers were interviewed to investigate the potential risk factors associated with bovine brucellosis in Peninsular Malaysia. Blood and vaginal swabs from cattle, whenever permissible, were collected to detect Brucella abortus. Questionnaire on the herd-level risk factors was developedincluding information on general farm management, biosecurity, medical history and public health awareness. Serological tests as well as culture and identification test were performed on the samples using Rose Bengal Plate Test and Brucella agar with supplement respectively. Univariate analysis was conducted for the potential risk factors and disease status and variables significant on the analysis were modeled into multivariate logistic regression. Seroprevalence was 1.8% (n=282) but samples were cultured negative. The Potential risk factors included farmers with more than one species of animals, presence of wildlife and history of abortion. About 78.9% of the farmers participated in the survey reported assisting their animals during delivery and 71.8% had not been using basic personal protective equipments such as glove and face mask to protect them from potentially contracting the infection. Similarly, 2.8% reported consumed unpasteurized milk from their animals. In addition, 19.7% have had episodes of fever with one farmers experienced undulant fever, and was later diagnosed as infected with brucellosis. A case-control study assessed the direct economic impact of bovine brucellosis in Peninsular Malaysia. This study incorporated the data from 71 farms based on the record of year 2010, surveillance data from DVS, data from DVS statistics on estimated cattle population and some conservative assumption based on proxy. The estimated direct economic cost of bovine brucellosis in Peninsular Malaysia was calculated using a simple spread sheet tool based on established method by Bennett et al 2003. The total economic loss in 2010 from sampled farms due to bovine brucellosis was estimated to be RM 1,445,367.30. Resources spent for the control and eradication accounted for 21% (RM302, 036) of the lost. This included the cost of vaccination of RM 13,736.00 and compensation cost of RM 288, 300.00 There were also significant devastating impacts to livestock farmers which accounted for 79% (RM 1,143,331.30) of the cost which included milk reduction losses of RM54,581.30, partial carcass condemnation ofRM 961,000.00 and loss due to abortion accounted for RM 127,750.00. A cross-sectional survey was carried out to evaluate the efficiency of the culling process prescribed for seroreactor cattle in Malaysia. Fourteen abattoirs in four states: Kelantan, Pahang, Negeri Sembilan and Selangor were visited and data on culled cattle from 2005 to 2008 were examined. The data was managed and analysed using Microsoft Excel. A total of 1,954 cattle were culled in the 14 abattoirs in the four states from 2005 to 2008. In 2005, 157.9% seropositive cattle were culled and for 2006, 2007 and 2008 only 51.5, 41.0 and 88.4% were culled respectively. The state of Selangor has the highest culling rate of 114.2%, followed by Pahang (94.0%), Negeri Sembilan (22.0%) while Kelantan had no record of culling within the study period. The overall culling rate for the studied states within the study period was 72.16%. In conclusion, bovine brucellosis in Peninsular Malaysia is widely distributed with major clustering of high risk areas. The disease occurrence was associated with several factors such as system of management, other species of animal in the farm and history of abortion. The economic burden of the disease was significant and estimated to be RM 1,445,367.30 in the year 2010. The area-wise eradication program of brucellosis was shown to be effective in reducing the prevalence. However, there is a need for improvement especially in area of enforcement of the culling policy.

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