Avian flu typically spreads between wild and domestic birds but can spread to other animals and people. There have now been more than 40 confirmed human cases in the United States, according to the Centre for Disease Control, most of which have been found in California. 

Over the past few months, the Mass Department of Public Health, working with the Department of Recreation and Conservation, has deemed dozens of water locations throughout the state closed due to high bacteria levels.

The Nigeria Center for Disease Control (NCDC) said no fewer than 2,122 suspected human cases, 411 confirmed cases, and 72 deaths have been recorded from Lassa fever in Nigeria this year.