The risk of introduction of swine vesicular disease virus into Kenya via natural sausage casings imported from Italy.

Pig production in Kenya is hampered by seasonal markets. As an alternative outlet for the finished pigs, several value-added meat-processing firms have been established. Sausage, which is produced using casings derived from intestines of pigs, is one form of processed meats. Kenya imports several kgs of natural casings every year; and a recent concern is Swine vesicular disease virus (SVDV), which has never been reported in Kenya, might be introduced via natural casings imported from Italy. To determine conditions (with associated probabilities) that could lead to the introduction of SVDV, a quantitative risk assessment model was developed. Using Monte Carlo simulations at 10,000 iterations, the probability of introducing SVDV was estimated to be 1.9x10-8. Based on the suggested volume of import and mitigations used in the analysis, contaminated casings derived from an estimated 0.003 (Range = 8.1x10-8 - 0.08) infected pigs will be included in the consignment each year. The critical pathway analysis revealed that rigorous surveillance programs in Italy have a potential to dramatically reduce the risk of introducing SVDV into Kenya by this route.

The risk of introduction of equine infectious anemia virus into USA via cloned horse embryos imported from Canada.

Deriving horse oocytes in the USA is hampered by the lack of abattoirs processing horse carcasses which could provide abundant quantities of ovaries from slaughtered mares. Therefore, several cloning industries in the USA are attempting to import cloned horse embryos from Canada. Like any agricultural commodity, cloned embryos pose a risk of introduction of exotic animal diseases into the importing country. Under such circumstances, risk assessment could provide an objective, transparent, and internationally accepted means for evaluating the risk. This quantitative risk assessment (QRA) was initiated to determine the risk of introduction of Equine infectious anemia virus (EIAV) into the USA via cloned horse embryos imported from Canada. In assessing the risk, a structured knowledge base regarding cloning in relation to Equine infectious anemia (EIA) was first developed. Based on the knowledge base, a scenario tree was developed to determine conditions (with mathematical probabilities) that could lead to the introduction and maintenance of EIAV along the cloning pathway. Parameters for the occurrence of the event at each node were estimated using published literature. Using @Risk software and setting Monte Carlo simulation at 50,000 iterations, the probability of importing an EIAV-infected cloned horse embryo was 1.8 × 10(-9) (R = 1.5 × 10(-12) to 2.9 × 10(-8)). Taking into account the current protocol for equine cloning and assuming the yield of 5 to 30 clones per year, the possible number of EIAV-infected cloned horse embryos ranged from 2.0 × 10(-10) to 9.1 × 10(-5) (Mean = 1.4×10(-6)) per year. Consequently, it would take up to 1.5 × 10(7) (R = 1.6 × 10(4) to 5.1 × 10(10)) years for EIAV to be introduced into the USA. Based on the knowledge base and our critical pathway analysis, the biological plausibility of introducing EIAV into USA via cloned horse embryos imported from Canada is extremely low.

A quantitative assessment of the risk of introducing foot and mouth disease virus into the United States via cloned bovine embryos.

The trade of livestock or their products between nations requires information on the risk of introducing infectious agents such as foot and mouth disease virus (FMDV). Although transmission pathways for FMDV vary, a recent concern in the United States (USA) is that it might enter via cloned embryos. A quantitative risk assessment model was developed to determine the scenarios (with mathematical probabilities) that could lead to the introduction and maintenance of FMDV via the importation of cloned bovine embryos. Using @RISK software with Monte Carlo simulation involving 50,000 iterations, the probability of introducing FMDV via cloned embryos was estimated to be 3.1 x 10(-7). Given the current cloning protocol, and assuming the annual importation of 250 to 1,700 (mean = 520) cloned embryos, the expected number of infected embryos ranges from 1.1 x 10(-7) to 4.4 x 10(-3) (mean = 1.6 x 10(-4)) per year. Critical pathway analysis showed that the risk of FMDV entering the USA by this route is extremely low.

Epidemiology of influenza A 2009 H1N1 virus pandemic in the U.S.

A novel influenza, Influenza A 2009 H1N1 virus outbreak, emerged in mid-April 2009, and by December 2009, spread across the world. This epidemiologic analysis uses the epidemiologic problem oriented approach to gather information for, and develop a quantitative risk assessment model that evaluates the likelihood of an influenza outbreak in the U.S., utilizing weekly incidence rates (WIR) and case fatality rates (CFR) stratified by age and the 10 U.S. regions. In addition ArcGIS was used to show variability regarding morbidity rate and WIR. Using data from the Centers for Disease Control and Prevention (CDC) Emerging Infections Program and applying Monte Carlo simulations with @Risk software, the analysis revealed morbidity to be highest in region 8 (1.27×10-2) and lowest in region 2 (0.13×10-2). Heat map results revealed WIR were higher in younger children, for all regions. Case fatality rates were 10 times greater in younger people than in older people and children. Using these different temporal-spatial epidemiologic methods can help decision-makers identify high-risk population clusters and help in prevention and control of pandemics.

A quantitative risk assessment for the likelihood of introduction of highly pathogenic avian influenza virus strain H5N1 into U.S. hunter retriever dogs.

Highly pathogenic avian influenza (HPAI) strain H5N1 has received great attention with regard to its potential spread to North America. This quantitative risk assessment, which is primarily based on wild bird carriage of HPAI from East Asia to Alaska, was conducted to assess the likelihood of a hunter retriever dog becoming infected after harvesting an infected waterfowl during the Alaskan hunting season. Using Monte Carlo Simulation with @Risk software, the expected probability of a hunter retriever dog becoming infected is 2.3 x 10(-8). This model can serve as a tool for decision makers in assessing the risk of HPAI strain H5N1 introduction into Alaska's hunter retriever dogs.

Prevalence of bovine tuberculosis in Ethiopian slaughter cattle based on post-mortem examination.

A study aimed at describing the magnitude and distribution of gross lesions compatible with bovine tuberculosis (BTB) in Ethiiopian slaughter cattle in five abattoirs (four municipal and one export) located in various cattle husbandry systems in Ethiopia was carried out from July 2006 to January 2007 using detailed meat inspection procedure. Five representative abattoirs (four municipal and one export) located in distinct livestock management systems were selected. A total of 3322 cattle; 2876 (86.6%) male, 446 (13.4%) female; 3094 (93.1%) indigenous zebu, 140 (4.2%) crossbred and 88 (2.7%) pure exotic cattle were included in the study. A nine-year meat inspection record was also analyzed to elucidate the trend of BTB in the local cattle population.Of the carcasses inspected, 337 (10.2%, 95%CI= [9.2-11.2]) had lesions suggestive of tuberculosis, 69 (20.5%) generalized and 268 (79.5%) localized.TB prevalence showed a marked variation between categories of age, breed, class of animals, abattoir, geographic origin and husbandry system. It was higher in old and young animals than middle age group; in exotic than local breed; in calves than other classes of animals. The highest and lowest prevalence of TB was recorded in Adama (24.7%, 95%CI= [21.1-28.7]) and Yabello abattoirs (4.2%, 95%CI= [2.6-6.6]), respectively. Cattle whose origin was from Addis Ababa and its surrounding areas had higher prevalence of TB infection (23.9%, 95%CI= [17.6-31.5]).Cattle maintained in dairy farms had high degree of exposure (23.9%, 95%CI= [16.7-32.9]) to the infection than those maintained in other types of management system. Analysis of meat inspection records also revealed an increasing incidence of TB over the years. Our study demonstrated a high prevalence of tuberculosis in Ethiopian slaughter cattle and this could infer to similar scenario in a reference cattle population in the country. In view of Ethiopia's increasing involvement in livestock export trade, the reported high prevalence of tuberculosis could be a major obstacle, particularly at this moment when sanitary requirements from importing countries are so much strict. Furthermore, the growing concern over increasing incidence of tuberculosis/HIV/AIDS co-infection, the high incidence of extra- pulmonary tuberculosis and a high risk of acquiring zoonotic tuberculosis among the majority of the population emphasize the need for paying the necessary attention towards the control of bovine tuberculosis.

Status of bovine tuberculosis in Addis Ababa dairy farms.

The study was conducted to determine the status of bovine tuberculosis in Addis Ababa, Ethiopia, by a comparative intradermal tuberculin test of 1,869 animals in 106 farms. Epidemiological information was also collected, taking into account factors chosen for their epidemiological significance and local livestock husbandry characteristics. In addition, milk samples were collected from tuberculin reactors for mycobacterial isolation and characterisation. Chi-square statistic, simple regression and multiple stepwise logistic regression were used to analyse the data. Of the 106 farms examined, 46 (95% confidence interval [CI]: 33.8% to 53.4%) contained comparative skin test reactors. Of the 1,869 animals, 443 (95% CI: 21.8% to 25.7%) were comparative skin test reactors. Furthermore, about 8.5% of tuberculin sensitive cows (12 of a sample of 141) secreted acid-fast bacteria in their milk. The microbes are described in more detail in the paper. Factors identified as possibly increasing the risk of bovine tuberculosis in Addis Ababa were herd size (large herd), farming (housing) condition (poor), and age (older animals). Similarly, as body condition scores improved from poor to medium and then to good, the likelihood of positive results significantly decreased (OR = 0.54; p < 0.01). Other factors including breed, sex, and physiological status of animals did not seem to significantly contribute to tuberculin sensitivity. The finding that large-size and intensively (often poorly) managed herds were at greater risk of bovine tuberculosis suggests that the significance of bovine tuberculosis is increasing in Addis Ababa parallel to an increasing dairy operation. If measures are not taken promptly, the impact on the economy and public health could be enormous.

Evaluation of abattoir inspection for the diagnosis of Mycobacterium bovis infection in cattle at Addis Ababa abattoir.

Detailed postmortem examinations were conducted to evaluate the efficiency of meat inspection procedures and to determine the distribution of lesions in Mycobacterium bovis-infected cattle. The study involved routine inspection at slaughter, collection of tissues for detailed examination in the laboratory, and bacteriological examination to identify M. bovis. Additionally, a 10-year (1992--2001) meat inspection record was analysed to determine tuberculosis trends in the past decade. chi2-Test and simple regression were used to analyse the data. Out of 1350 cattle examined, 1.5% were found with tuberculous lesions. Routine abattoir inspection detected only 55% of cattle with confirmed lesions. Fifty-four per cent of tuberculous lesions were found in the lungs and thoracic lymph nodes, 23% in the lymph nodes of the head, and the remaining 23% in the mesenteric and other lymph nodes of the carcase. M. bovis was additionally isolated from an animal that had no gross lesions of tuberculosis. On average, the annual rate of whole-carcase condemnation due to generalized tuberculosis was 0.024% and it has increased annually by 0.34% over the past decade. The rate of whole-carcase condemnation indicates a high degree of TB transmission and requires immediate attention from both the economic and public health points of view. The lower sensitivity of routine abattoir inspection confirms the importance of improving necropsy procedures.

Survival analysis of calves and reproductive performance of cows in commercial dairy farms in and around Addis Ababa, Ethiopia.

A study was conducted at five locations to determine the survival rate of calves and to estimate the performance level of improved dairy cows under commercialized farming systems in Ethiopia. Seven hundred and one calves born from 1997 to 1999, and 797 cows were included in the study. Cumulative calf/heifer survival at 360, 540 and 720 days was 80%, 76% and 70%, respectively. Number of services per conception averaged 2 while mean age at first service and days open were 850+/-18 and 192+/-11 days, respectively. Calf survival, days open and age at first service were significantly affected by breed and management factors (p <0.05), whereas parity significantly affected the number of services per conception and days open. There was a tendency towards improved performance over the years. This was especially so for calf survival and days open. Clearly, all the traits measured varied among study farms, indicating that substantial improvement can be achieved through better management. This paper describes these individual traits of improved dairy breeds under commercialized farming systems in Ethiopia.

Tuberculous lesions not detected by routine abattoir inspection: the experience of the Hossana municipal abattoir, southern Ethiopia.

The efficacy of the meat inspection procedures implemented for the detection of tuberculous cattle was evaluated by testing for bovine tuberculosis in 751 animals. The study involved routine inspection at slaughter, collection of tissues for detailed examination in the laboratory, and bacteriological investigation to identify Mycobacterium bovis. Of the 751 carcasses examined, 34 (4.5%) were found to have tuberculous lesions. Routine abattoir inspection detected only 29.4% of the carcasses with visible lesions. Eighty-four percent of the tuberculous lesions were found in the lungs and thoracic lymph nodes, 11.5% in the lymph nodes of the head, and the remaining 4.5% in the mesenteric and other lymph nodes of the carcasses. In addition, M. bovis was isolated from a carcass that presented no gross tuberculosis lesions. The low sensitivity of routine abattoir inspection demonstrates that existing necropsy procedures should be improved.