Anyone who swims in Africa's Lake Malawi risks contracting a parasitic infection known as bilharzia or schistosomiasis, U.S. doctors warned Friday.

Lake Malawi may be promoted to tourists as a safe freshwater lake but in fact there is a good chance of infection, Dr. Martin Cetron and colleagues at the Centers for Disease Control in Atlanta said in a report in the Lancet medical journal.They studied nearly 1,000 foreigners living in Malawi and found more than 300 had evidence of infection in their blood.

The more often the foreigners had visited resorts at the lake, the more likely they were to be infected, Cetron's group found.

"Transmission of schistosomiasis is occurring in Lake Malawi, a previously under-recognized source of transmission," they wrote. "Recreational water contact at popular resorts on Lake Malawi is the most likely source of infection."

View Comments

Schistosomiasis is caused by a parasite carried by a snail.

Join the Conversation
Looking for comments?
Find comments in their new home! Click the buttons at the top or within the article to view them — or use the button below for quick access.