Risks from contaminated food and drink

Contamination of food and drink with the leptospira bacterium is certainly possible, but most people will have reached this page when looking for information on the ‘leptospirosis caught from a soda can’ email, which is totally untrue.

The situations where contamination risks exist have to satisfy certain criteria:-

  • Urine from a carrier animal must come into contact with the food or drink directly.
  • Food items must not dry out at any stage. Drinks must have a neutral pH.
  • The item must be consumed without cooking or washing.

Many food types such as grain will have rodent activity in the storage and farming areas, but as they rapidly dry out, the bacteria cannot survive for long enough to cause infections. Fruit and vegetables are similarly safe once dried, and the bacteria cannot penetrate the skins found on most fruit and vegetables so surface washing is all that is required. Cooking at temperatures of 100°C or above will make any food item safe in terms of leptospires.

Meat from infected animals is also relatively safe to eat once cooked thoroughly, even the organs with high concentrations of bacteria such as the kidneys. We would not advise using infected animals as a food source, but in many areas it’s impossible to tell. One potential issues is that if the animal was acutely ill at the time of slaughter, the meat may taste unpleasant due to uric acid levels in the blood. The bacteria will survive in raw meat for a while, so handling and preparing raw meat may be a possible risk if you cut yourself in the process.

Waterproof containers (cans, bottles, etc.) are extremely safe as the bacteria will rapidly dry out and die on their surfaces, and cannot penetrate into the food or drink inside. Where containers have been contaminated with urine from a carrier animal the simplest safety precaution is to wash the containers in a detergent solution, then allow them to dry for at least an hour before use. We have no records of cases where humans have been infected from commercially-sold food in the developed world, however in the developing world it is potentially possible for local groundwater to be used in food and drink preparation without a boiling stage, so allowing the bacteria to survive. Cold food such as salads can retain water and so maintain a bacterial colony in some situations.