May 22 (HealthDay News) -- There was an unusually large number of severe coxsackievirus infections in infants in the United States in 2007, a new federal study says.

Coxsackievirus B1 (CVB1) is a form of enterovirus, which usually causes mild disease but can cause severe, life-threatening illness in newborns.

According to the Nemours Foundation, outbreaks of coxsackievirus infections typically occur in cooler climates during the summer and fall, although they can happen year-round in tropical regions. In most cases, coxsackieviruses cause mild flu-like symptoms and go away without treatment. But in some cases, they can lead to more serious infections.

As of Feb. 1, 2008, the National Enterovirus Surveillance System had received 514 reports of enterovirus infections in 36 states for 2007. Coxsackievirus B1 was the most commonly detected enterovirus reported to NESS, accounting for 25 percent of all enterovirus-related reports. CVB1 illnesses were reported in 19 states and caused at least five deaths.

Among the 95 coxsackievirus B1 cases with known patient age, 53 percent of the patients were less than 1 month old, and 68 percent were less than 1 year old. Fifty-eight percent of all coxsackievirus B1 cases were reported in California (38) and Illinois (28).

The findings are published in Friday's edition of the Morbidity and Mortality Weekly Report, from the U.S. Centers for Disease Control and Prevention.

Transmission of enteroviruses can be controlled through use of good hygiene practices, such as washing hands thoroughly (especially after diaper changes); disinfecting contaminated surfaces with chlorine-containing household cleaners; and not sharing utensils and drinking containers, according to the CDC.

SOURCE: May 23, 2008, Morbidity and Mortality Weekly Report, U.S. Centers for Disease Control and Prevention, Atlanta