Cheese from Mexico linked to TB-like infections

Several New York City cases of a type of tuberculosis that normally affects cattle appear to be due to fresh cheese made from unpasteurized cow’s milk in Mexico, investigators from the Centers for Disease Control and Prevention report.

Infection by Mycobacterium bovis, the culprit in these cases, used to be common before milk pasteurization but is a rarity these days.

Following the death of a 15-month-old boy in March 2004 due to abdominal infection with Mycobacterium bovis, Dr. A. Winters, from the New York City Department of Health and Mental Hygiene, and colleagues investigated all cases of human M. bovis infection identified in that city since 2001.

They report their findings in the CDC’s Morbidity and Mortality Weekly Report.

The results of rapid testing revealed that M. bovis made up 1 percent of the 3417 confirmed cases of tuberculosis that occurred between 2001 and 2004. The 35 cases included 12 children younger than 15 years old and five children younger than 5 years old.

Eleven patients were born in the US, while the rest were born in Mexico, the Dominican Republic, Guatemala or Guyana. All of the patients younger than 5 years old were born in the US of parents from Mexico.

The investigators interviewed 23 patients or their parents, and found no suggestion of airborne, person-to-person transmission of M. bovis. However, 19 reported having eaten cheese produced in Mexico while they were living the US.

The authors of the report note that in a previous study, 17 percent of cattle tested in Mexico were infected with M. bovis, and that 20 percent of cow’s milk in Mexico used for making fresh cheese is not pasteurized.

“All persons should avoid consuming products from unpasteurized cow’s milk,” the researchers advise.

SOURCE: Morbidity and Mortality Weekly Report, June 24, 2005.

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