A 10-year-old boy from Altai Republic in Siberia has contracted bubonic plague, according to TASS News Agency. It is believed he caught the serious bacterial infection during a hiking trip.

Oriental rat flea, Xenopsylla cheopis/CDC

The region he and his fellow hikers traveled is well known for it’s marmot population, which is a plague carrier.

The child was hospitalized Tuesday in serious but stable condition.

Plague is an infectious disease caused by the bacterium, Yersinia pestis. It is found in animals throughout the world, most commonly rats but other rodents like ground squirrels, prairie dogs, chipmunks, rabbits and voles. Fleas typically serve as the vector of plague. Human cases have been linked to the domestic cats and dogs that brought infected fleas into the house.

People can also get infected through direct contact with an infected animal, through inhalation and in the case of pneumonic plague, person to person.

Yersinia pestis is treatable with antibiotics if started early enough.

There are three forms of human plague; bubonic, septicemic and pneumonic.