Mexico-born adults prone to severe chickenpox

Mexican-born adults living in the U.S. apparently have higher rates of complications with chickenpox infection than do U.S.-born adults, according to a new report.

Chickenpox can now be prevented by immunization. "Physicians need to assess vaccination histories of foreign-born persons, including adult workers," lead author Dr. M. Carolina Danovaro-Holliday from the Pan American Health Organization in Washington, DC, told AMN Health.

Chickenpox "is more severe and more likely to result in complications in adults than in children," Danovaro-Holliday pointed out. The antiviral drug acyclovir, given within 24 hours of the appearance of a rash, "can reduce the severity of varicella disease and should be routinely offered to adults with varicella."

To prevent infection in the first place, doctors should "vaccinate unvaccinated persons (both children and adults) without history of disease whenever these persons come in contact with a health service," she said

Danovaro-Holliday and colleagues from the Centers for Disease Control and Prevention in Atlanta, and the Alabama Department of Public Health, Montgomery, investigated an outbreak of chickenpox among 18 adults born in Mexico.

Five of the 18 cases were severe, the authors report in the medical journal Clinical Infectious Diseases, and four of the people with severe cases lived in the same household.

One third of the people who did not become infected, but resided in the same complex, were susceptible to chickenpox, according to the results of blood tests, and all but one of these were born in Mexico.

In the factory where many of the patients worked, 11 percent of the other workers were susceptible to varicella.

An analysis of the factory worker data showed that Mexican-born workers were more than five times more likely than those born in the United States to have no immunity to chickenpox.

"Physicians serving immigrant populations should be aware that adults from tropical regions have a higher rate of susceptibility (to chickenpox) than do persons born in the United States," the investigators conclude.

"This may be also true for other vaccine-preventable diseases," Danovaro-Holliday commented. "Therefore, the workplace might be an environment for ongoing disease transmission, or represent an access point to vaccinate susceptible persons in a minority community experiencing a vaccine-preventable disease."

SOURCE: Clinical Infectious Diseases, December 1, 2004.