Objective—To determine biosecurity practices and travel history of individuals exhibiting livestock at the 2005 California State Fair.
Study Population—137 individuals exhibiting livestock at the fair.
Procedures—Exhibitors were asked to complete a survey to gather information about the animals they exhibited, the biosecurity practices they used, and the distances they traveled to exhibit their animals.
Results—132 of the 137 (96%) respondents came from California, with respondents representing 40 of California's 58 counties. Median number of livestock exhibitions attended by respondents during the past 12 months was 3 (range, 1 to 7). Respondents indicated that 787 of the 812 (97%) animals they exhibited would be returned home after the fair. Nine (7%) respondents indicated that they did not take any particular biosecurity precautions before arriving at the fair, and 14 (10%) indicated that they did not take any particular biosecurity precautions while at the fair. Only 36 (26%) respondents indicated that they quarantined their animals when returning to their farm of residence after the fair.
Conclusions and Clinical Relevance—Results indicated that there was extensive movement of livestock among exhibitions in California, posing a potential threat for widespread dispersion of disease throughout the state and beyond, particularly given the low percentages of exhibitors who used various biosecurity measures.
Objective—To estimate potential spread of foot-and-mouth disease (FMD) if introduced from wild pigs in California and to evaluate efficacies of various control strategies.
Sample Population—Data for California livestock and from hunter surveys on wild pigs in California.
Procedures—A spatial, stochastic simulation model was used to simulate FMD epidemics that might occur if a dairy or beef herd were infected from contact with a wild pig. Index herd location and type were examined, in addition to different statewide movement ban (SWMB) durations, to determine their effect on extent of the epidemic.
Results—Duration, number of infected premises, size of simulated outbreak, number of culled animals, and spatial distribution of infected herds resulting from the simulated outbreaks varied considerably among geographic regions, depending on index case type and location. Outbreaks beginning in the southern region of California were consistently longest, whereas those beginning in the northern region were shortest. The largest outbreaks resulted from index cases located in the southern and valley regions, whereas outbreaks were smallest when originating in the Sonoma or northern regions. For all regions, when the index herd was a dairy herd, size and duration of the outbreak were consistently reduced with implementation of an SWMB ≥ 3 days.
Conclusions and Clinical Relevance—Introduction of FMDV from wild pigs into a dairy or beef herd could result in a large and rapidly spreading outbreak, potentially affecting large numbers of herds. Size and duration of the outbreak might be reduced with an SWMB; however, the impact is highly dependent on the index herd type and location.
Objective—To estimate contact rates and movement variables for shipments of beef cattle to and from producer premises in California.
Sample Population—583 beef producers in California.
Procedures—Questionnaires were developed and distributed to beef cattle producers in California. The study period was from April 20, 2005, through September 7, 2006. Data from completed questionnaires were entered manually into an electronic format. Descriptive statistical analyses were performed.
Results—Median number of interstate animal movements (movement of cattle into or out of California) was 0.17/mo; on the basis of this median, beef cattle were moved interstate > 2 times/y. Respondents kept beef cattle at up to 5 locations throughout the year. More than 40% of the movements from the respondents' premises were to a sale yard or auction facility.
Conclusions and Clinical Relevance—Frequency of animal movements in this statewide study differed from values in another study of monthly shipments of animals to and from beef operations in 3 counties of California. The survey reported here revealed more frequent movements of animals to and from beef operations of all sizes. In addition, there were more high-risk indirect contacts on beef operations than has been reported previously. However, the number of low-risk indirect contacts was similar for small beef operations but less for large beef operations than has been reported elsewhere. Epidemic simulation models for California based on data in earlier studies likely underpredicted disease transmission involving beef herds.
Objective—To estimate the potential spread of foot-and-mouth disease (FMD) if infected livestock had been exhibited at the 2005 California State Fair.
Animals—Dairy cattle, dairy goats, and pygmy goats exhibited between August 24 and August 28 by 195 exhibitors.
Procedures—2 stochastic models were used to simulate epidemics of FMD that might originate from 1, 3, 5, 7, or 10 index cases at the state fair. Data obtained from state fair exhibitors were used to determine the spatial distribution and types of herds to which livestock visiting the state fair returned.
Results—Mean estimated numbers of latently infected animals on day 5 were 12.3 and 75.9, respectively, when it was assumed that there were 1 and 10 index cases. Regardless of the number of index cases, mean estimated numbers of subclinically infected and clinically infected animals were low throughout the 5-day study period. Mean estimated duration of the resulting epidemic ranged from 111 to 155 days, mean number of infected premises ranged from 33 to 244, and mean probability that at least 1 animal that became infected with FMD would subsequently leave the state ranged from 28% to 96% as the number of index cases increased from 1 to 10, respectively.
Conclusions and Clinical Relevance—Results suggested that following introduction of FMD at the California State Fair, infection would likely go undetected until after animals left the fair and that the subsequent outbreak would spread rapidly.