Faced with a rash of shark deaths marked by brain swelling, Canadian and American scientists are trying to solve a marine mystery.

Faced with a rash of shark deaths marked by brain swelling, Canadian and American scientists are trying to solve a marine mystery.

In recent months, bird flu has started raising red flags among scientists and public health officials. Apoorva Mandavilli, a New York Times reporter who covers infectious diseases, explains why we need to start taking bird flu seriously.

The cases have spurred new pet food safety rules and poultry surveillance efforts.

Humans are known to invent private hand gestures. Chimps in the wild do, too, a new study suggests.

The bull moose had fallen into a lake in the Adirondacks and been in the frigid waters for about two hours before rescuers arrived and used a chain saw to free it.

A multibillion-dollar expansion helped the canal accommodate king-size cargo ships. It might also be fueling ecological upheaval.

It is not uncommon for planes to strike wildlife, but most episodes don’t result in deaths or serious injuries.

New federal rules call for testing unpasteurized milk from dairy processors and for farm owners to provide details that would help officials identify and track cases more easily.

© Tim Gruber for The New York Times

On America’s large dairy farms, milking is a vast operation, and the potential for disease transmission is worrying, health experts say.

© Tim Gruber for The New York Times