Two children and two adults became ill from E. coli infections after visiting an animal farm run by the city of Everett in Washington state.

The Daily Herald of Everett reported that one child required hospitalization but has since been discharged. One of the adults worked at the farm. The E. coli serotype was not been identified.

The Animal Farm at Forest Park, which gets about 25,000 visitors a year, is run by Everett’s parks department and features sheep, calves, piglets, chickens, goats, ducks, a horse, a pony and rabbits, according to the newspaper.

Animal farms and petting zoos are a common source of exposure to disease-causing pathogens. According to the Centers for Disease Control and Prevention, between 1996 and 2010 approximately 150 outbreaks of disease in the U.S. were linked to animals in farms open to the public.

In England, almost 100 people — including 76 children under the age of 10 — were sickened by E. coli O157:H7 contracted at a public farm in Surrey in the summer of 2009. That same year, an outbreak in Colorado originating at the National Western Stock show led to 30 illnesses and 9 hospitalizations.

In 2003 United States Department of Agriculture study of more than 20 county fairs found E. coli O157:H7 in 13.8 percent of beef cattle, 5.9 percent of dairy cattle, and slightly smaller percentages of sheep, pigs and goats — nearly the same percentages found in animals in feed lots.

Last month, new guidelines on how to prevent the spread of disease from animals to humans in public settings such as animal farm, petting zoos and county fairs were issued by the National Association of State Public Health Veterinarians.

The most crucial step in avoiding zoonotic disease is washing one’s hands as often as possible after handling farm animals, says the report.