It's one of medicine's biggest mysteries — why sometimes our immune system attacks our own bodies. Autoimmune diseases affect as many as 50 million Americans and millions more worldwide. They're hard to diagnose and treat, and they're on the rise. A Massachusetts woman's journey with one named lupus — called the disease of 1,000 faces for its baffling variety of symptoms — offers a snapshot of the burden. Now researchers are decoding the biology behind these debilitating diseases in hopes of eventually treating the causes, not just the symptoms.

A mosquito-borne virus more common in South America has been detected in the United States. Health officials say the chikungunya virus has been identified in a patient living in the suburbs of New York City who began experiencing symptoms in August. Authorities say it's the first locally acquired case identified in any state since 2015, meaning the patient didn't travel outside the country before becoming infected. It's also the first locally acquired case that New York has ever seen. Chikungunya typically produces symptoms including fever, muscle pain, nausea, fatigue and a rash.

A study that upended medical practice by recommending feeding babies peanut products early to prevent allergies has had a big effect in the real world. A new study in the medical journal Pediatrics found that peanut allergies in children ages 0 to 3 declined by more than 27% after guidance was first issued, and by more than 40% after it was expanded in 2017. For decades, doctors had recommended delaying feeding children peanuts and other foods likely to trigger allergies until age 3. The approach has helped 60,000 children avoid food allergies, including 40,000 children who otherwise would have developed peanut allergies.

COVID-19 activity is rising in much of the country. Data released Friday by federal health officials shows overall respiratory virus spread is low. But COVID-19 is rising in many states in the mid-Atlantic, the South, the southeast and on the West Coast. More people of all ages are going to emergency rooms because of COVID-19. Flu and RSV activity remain very low. Doctors say hot summer weather can drive people indoors where respiratory viruses like to spread.

The U.S. surpassed 1,000 measles cases Friday, even as Texas posted one of its lowest counts of newly confirmed cases since its large outbreak…

Three people have died from measles-related illnesses in the U.S. since the highly contagious virus started ripping through West Texas in late January. The U.S. has more than doubled the total number of measles cases in 2024. Texas, New Mexico, Ohio, Kansas and Oklahoma all have active measles outbreaks. Measles is caused by a highly contagious virus that's airborne and spreads easily when an infected person breathes, sneezes or coughs. It is preventable through vaccines, and has been considered eliminated from the U.S. since 2000. Measles cases also have been reported in Alaska, California, Colorado, Florida, Georgia, Kentucky, Maryland, Michigan, Minnesota, New Jersey, New York, Pennsylvania, Rhode Island, Tennessee, Vermont and Washington.

An American biochemist whose research has helped scientists make inroads on treating coronavirus and HIV has won this year's Wolf Prize, a major Israeli award in the arts and sciences. The Wolf Fund said Professor Pamela Björkman of Caltech has "unlocked the secrets of how the immune system identifies and battles pathogens, developing game changing approaches to combat some of humanity's most formidable viral enemies." Eight others also received the state-funded prize, which has been awarded annually for 47 years. Many of the award winners have gone on to receive Nobel prizes.