Virus

Viruses and bacteria have been around for billions of years, but which came first?

Many factors affect the infectious period of seasonal influenza, commonly called "the flu," but there are some good rules of thumb for when it's safe to return to work or school.

A new study in mice suggests that dysfunctional mitochondria may change the composition of the gut microbiome and thus drive Crohn's disease.

A fever and a nasty cough can be symptoms of a range of respiratory illnesses. An antigen test that narrows down the culprits can speed up diagnosis and recovery.

Roundworms harbor viruses, which could be responsible for these parasites' painful symptoms in humans, scientists theorize.

Scientists identified more than 600 viruses in samples taken from bathrooms in the United States. The viruses infect bacteria — not people — and scientists say they may provide more benefits than causes for concern.

Data from the Southern Hemisphere hint that this year's flu shot lowers the risk of hospitalization among vulnerable demographics.

Unlike past flu shots, flu vaccines for the 2024-2025 season don't contain the "Yamagata lineage" of influenza viruses because evidence suggests that type of flu no longer exists.

The latest human case of bird flu in the U.S. occurred in a patient with no reported exposure to affected animals, sparking questions over whether the virus is spreading between people. Experts say that's unlikely but argue the case raises other concerns.

There's a new way to screen for high-risk HPV, a viral infection that can lead to cervical cancer. This alternative method of collecting samples for cervical cancer screening doesn't require a speculum.