United States Department of Agriculture
Animal and Plant Health Inspection Service
Brucella melitensis in Texas
Summary:
Brucella melitensis was identified in a Texas cow during routine market cattle testing. As of October 13th, additional testing has not revealed any other cases. If the situation remains localized, there should not be any impact on APHIS’ accomplishment of its eradication goals or on trade. Human health should not be impacted either as long as the situation remains localized.
How extensive is the situation?
B. melitensis was identified in a cow tested during routine market cattle testing in Texas. Milk and tissues from the cow were used in making the diagnosis. The infected cow came from a herd located in Starr county approximately 15 miles northeast of Rio Grande City. Testing has begun on the herd as well as on the surrounding operations. As of October 13th, 55 of the 80 head located in the same group as the infected cow have tested negative as have an additional 30 head located in a second group of 80 head also owned by the rancher but kept physically separated. The affected group is being depopulated. Approximately 10 surrounding operations located within 1 mile of the affected operation have been identified for testing. All cattle, sheep, and goats on these 10 operations will be tested. (Source: Dr. John Lomme, Assistant AVIC, Texas)
The herd on the affected operation was assembled in 1994 and is a combination of registered animals and animals purchased at local markets from other local producers. A Mexican origin for one or more of the cows in the herd can not be ruled out. (Source: Dr. John Lomme, Assistant AVIC, Texas)
Background Information on B. melitensis
Although bovine brucellosis in the U.S. is most commonly caused by Brucella abortus, cattle can become infected with B. melitensis. B. melitensis is more typically found in sheep and goats. In sheep and goats, B. melitensis is currently found in Europe, Africa, Asia, and Bolivia and Mexico in the Americas. B. melitensis was last found in sheep and goats in the U.S. in the early 1970s. Recently, B. melitensis infection in cattle has become a significant problem in the Middle Eastern countries of Israel, Kuwait, and Saudi Arabia. Transmission of Brucella spp. between animals usually occurs by oral exposure to aborted fetuses, placentas, vaginal discharge, and drainage from abscesses.
Wildlife have not been reported to play an important role in the transmission of B. melitensis to domestic livestock. B. melitensis has been isolated from hares in northern Europe, however (Witter, 1987).
In humans, B. melitensis causes the most important clinical disease of the Brucella organisms. Historically in the U.S., brucellosis was mainly described as an occupational disease of individuals, mostly male, who were exposed through work with livestock or animal products. More recently it has caused more infections in people through ingestion of infected unpasteurized dairy products, particularly soft cheeses made from sheep and goat milk. During the years from 1973 through 1992, 426 cases of human brucellosis were reported in California. Of these, 185 cases were attributed to B. melitensis, often due to consumption of milk and cheeses in Mexico (Chomel, 1994). Human cases of B. melitensis are found annually in Texas. These cases are typically associated with dairy products consumed by Hispanic families traveling back and forth to Mexico (Source: Texas Department of Health).
What is the livestock production in the affected area?
Starr county and its 4 surrounding counties account for only a small percentage of Texas’ livestock inventory (Table 1). The 5 counties combined have 1.3% of the total cattle in Texas and less then 1% of sheep and goats.
Table 1. Numbers of livestock animals and numbers of farms in affected county (Starr)
and 4 counties which border the affected county, 1997
| County |
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| animals |
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| Brooks | ||||||
| Hidalgo | ||||||
| Jim Hogg | ||||||
| Starr | ||||||
| Zapata | ||||||
| Total of 5 counties | ||||||
| Total for Texas (x 1,000) | ||||||
| % of total from 5 counties | ||||||
Source: NASS, Census of Agriculture, 1997
Cattle and calves are Texas’ top agricultural commodity, accounting for 43% of the state’s total farm receipts in 1997. In 1998, Texas had 16.3% of total US inventory of beef cows, 21% of cattle on feed, and 19.6% of sheep and lambs (Tables 2 and 3). Texas is the only state that reports numbers of goats. (Source: USDA,ERS; USDA,NASS)
Table 2. Livestock inventory and value of production in Texas and U.S., 1998
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| Texas |
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| All cattle and calves, Jan 1, 98 | ||||||
| beef cows | ||||||
| milk cows | ||||||
| cattle on feed* | ||||||
| Sheep & lambs, Jan 1, 98 | ||||||
| Goats, 1997 | ||||||
* Total number during 1998
Source: USDA:NASS:Agricultural Statistics, 1999; Census of Agriculture, 1997
Table 3. Operations with livestock, Texas and U.S., 1998
| Texas operations, number | U.S. operations, number | ||
| Cattle and calves | |||
| beef cows | |||
| milk cows | |||
| Sheep & lambs |
What are U.S. exports of cattle, swine, sheep and goat products and how might the finding of B. melitensis affect exports?
The total value of U.S. cattle, sheep & goat exports was $190.3 million in 1998. From January to July 1999, the value of U.S. exports of cattle, sheep and goats totaled $75.3 million. Nearly 60% of the total value in 1998 was exported to Mexico; exports to Canada accounted for 34%. From January to July 1999, $37 million of cattle, sheep and goats was exported to Mexico and $32 million was exported to Canada. Mexico imported approximately 800 thousand cattle, sheep and goats from the U.S. in 1998 and nearly 360 thousand animals from January to July 1999. Canada was a distant second to Mexico, importing approximately 130 thousand animals in 1998 and 105 thousand from January to July 1999. A more detailed picture of U.S. exports is provided in the table in Appendix A.
Texas is one of the main exporting states for live animals. The Economic Research Service estimates that Texas’ share of the value of total U.S. live animal and meat (excluding poultry) exports in FY 1998 was 13 percent with a value of around $655 million.
Exported U.S. cattle are currently tested for brucellosis prior to exportation. For goats, Mexico requires certification that the animals come from a herd that is free of B. melitensis, and Canada requires a test for B. abortus. Sheep are required by Mexico to be tested for B. ovis, while Canada has no testing or certification requirements regarding brucellosis in sheep. A finding of B. melitensis should not alter the ability of the U.S. to export livestock to its major trading partners (Mexico and Canada), although specific testing or certification requirements may be affected if additional cases are discovered. The U.S. and Mexico have had a history of disputes over phytosanitary requirements.
What does the meat packing industry look like in Texas?
In the last decade, human brucellosis cases in Texas have only rarely been associated with slaughter facilities (
Source: Texas Department of Health). In 1999, two cases of
B. suis were diagnosed in workers at a small game meat processing facility which slaughtered feral swine. Within Texas, approximately 20% of the state’s 186 meat packing and processing facilities are located within 220 miles of Starr county. Each processing plant employs an average of 110 individuals.
(Source: U.S. Department of Commerce, County Business Patterns, 1997)
Conclusions
If it remains isolated, the finding of B. melitensis in Texas should not have a major impact on U.S. brucellosis eradication goals. Live animal exports should also remain unaffected, since brucellosis testing is already required by the major importing countries of Mexico and Canada. The type of testing or specific certification required may be affected if additional cases of B. melitensis are found.
If you have questions or would like to comment on this worksheet, please reply to this message or contact Chris Kopral at (970) 490-7819 or Carol Tuszynski at (970) 490-7893.
Prepared by: Center for Emerging Issues, Centers for Epidemiology and Animal Health
Appendix A: Top U.S. Export Markets for Various Livestock
| Live Cattle | |||||
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| World | World | ||||
| Mexico | Canada | ||||
| Canada | Mexico | ||||
| Lebanon | Lebanon | ||||
| Egypt | Saudi Arabia | ||||
| Saudi Arabia | Colombia | ||||
| Live Sheep | |||||
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| World | World | ||||
| Mexico | Mexico | ||||
| Canada | Canada | ||||
| Dominican Republic | Dominican Republic | ||||
| Live Goats | |||||
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| World | World | ||||
| Mexico | Mexico | ||||
| Canada | Canada | ||||
| Dominican Republic | Taiwan | ||||
| Brazil | Philippines | ||||
Bean NH, et al. Foodborne disease outbreaks, 5-year summary, 1983-1987. Morbidity and Mortality Report, 1990;39(SS01):15-23.
Witter JF. Brucellosis. In, Brucellosis in Wild Animals, ed MM Bememtsuva, Amerind Publishing Co Ltd, New Delhi;1987:280-287.
Chomel BB, et al. Changing trends in the epidemiology of human brucellosis in california from 1973 to 1992; a shift toward foodborne transmission. J Infect Dis 1994; 170(5):1216-23.