Commercial sex is still a major source of infection.

Check for other possible sources of infection or recent illness.

A study conducted indicated that they are a time bomb source of infection.

The only real cure is to find the original source of infection... and kill it.

An epidemiological investigation revealed a common source of infection: a polluted water supply.

The main source of infection for children is mother-to-child transmission.

Feeding dead animal remains to cattle... is a known source of infection.

Check for any other possible sources of infection or recent illness.

in-house air: soil, smoking, heating, use of gas burners, insufficient ventilation, sources of infection, keeping of pet animals;

working environment: sources of infection, polluted or infected materials, technical systems and the working process, failure to observe safety requirements.