Last week’s Centers for Disease Control and Prevention Morbidity and Mortality Weekly Report detailed a case of firefighters in Indiana and Michigan contracting cryptosporidiosis after saving baby calves from a barn fire.
Out of the 34 responding firefighters, 20 reported gastrointestinal illness about a couple of weeks after responding to the fire. Cryptosporidium parvum was identified in human stool specimens, calf fecal samples, and a swimming pond from which water was used (along with local hydrant water) to help extinguish the fire.
The barn housed approximately 240 week-old calves, and investigators hypothesized that exposures to calves or contaminated drinking water were potential infection sources. The report says patients were statistically more likely than nonpatients to have had direct calf contact (e.g., carrying or leading calves from the barn).
The Michigan local health department recommended that the farmer who owned the barn treat the well water, and also recommended the farmer's family no longer use the pond for swimming. The family also was notified of the presence of Cryptosporidium as well as Giardia in their calf population.
Practicing thorough hygiene to reduce fecal contamination and fecal-oral exposures was recommended to the family and firefighters. Furthermore, recommendations were provided to decontaminate firefighter tanker trucks, clothing, and other equipment to prevent further exposure. No secondary cases were identified through firefighter interviews or state disease surveillance system reports.
The CDC says this is the first report of cryptosporidiosis transmitted during a firefighting response. To prevent similar outbreaks, adequate drinking water during firefighting responses and decontamination of firefighting equipment are recommended. Firefighters should only consume treated or bottled water, or sports drinks. Firefighting equipment and clothing should be decontaminated at the scene whenever possible, especially if grossly contaminated with feces, to reduce transmission of Cryptosporidium, Giardia, and other zoonotic enteric pathogens (e.g., E. coli, Salmonella, and Campylobacter).
The CDC recommends that clothing contaminated with feces should be machine-washed and heat-dried on the highest clothes dryer heat setting for 30 minutes whenever possible; all other non–machine-washable items and equipment should be cleaned with soap and water to remove gross fecal contamination, air-dried, and left in the sun for at least 4 hours after drying. For equipment that cannot be cleaned with soap and water or equipment that contacts the mouth (e.g., respirator pieces), soaking in 3% hydrogen peroxide solution for 20 minutes is recommended after consulting manufacturer guidelines.
Iowa State University’s Center for Food Security and Public Health says Cryptosporidium parvum transmission is usually by the fecal-oral route. Sporulated oocysts are shed in the feces and are immediately infectious. If in a moist environment, the shed oocysts can survive for 2 to 6 months.
Direct transmission between animals and humans is common. It is estimated that 50% of dairy calves shed oocysts; calves can then spread cryptosporidiosis to each other or to humans. Humans and animals can ingest the organism through eating or drinking contaminated water or food, or from contacting or licking contaminated non-living objects (fomites).
Information from the University of Wisconsin says very strict hygiene is needed to minimize the exposure of calves to Cryptosporidium parvum. Isolation of newborns from other animals is the best prevention method. Newborn calves should be fed colostrum early, placed in individual housing, and kept clean and dry. Good calf rearing techniques help build healthy calves and go a long way in preventing protozoan infestations in calves. If cryptosporidium is a problem, newborn calves should be housed in strictly isolated pens and preferably in a separate building.
Resources on Cryptosporidium parvum