The Rev. Jesse Jackson is in the hospital with a rare neurological disorder. Jackson's Chicago-based civil rights organization says the 84-year-old has progressive supranuclear palsy and is under observation. Jackson has suffered from symptoms consistent with Parkinson's disease and disclosed a diagnosis in 2017. But during a Mayo Clinic visit in April, doctors confirmed a diagnosis of PSP, which can have similar symptoms to Parkinson's. He has continued to make public appearances including at last year's Democratic National Convention. He's been using a wheelchair and family members say he can no longer speak.

Baby formula manufacturer ByHeart recalled all of its products sold nationwide Tuesday. The move comes days after some batches were recalled amid an expanding outbreak of infant botulism. According to state and federal health officials, at least 15 babies in 12 states have been sickened in the outbreak since August, with more cases pending. All the infants were hospitalized after consuming ByHeart formula. Parents and caregivers who have the formula in their homes should immediately stop using it and dispose of the product. Babies with symptoms of infant botulism need immediate medical care.

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.

Nature walks are good for you, but can a city stroll be just as good? Walking in nature has been shown to boost physical and mental health, improve cognitive performance, lower stress and restore attention. But researchers say there are also mental-health benefits to walking in urban areas. You just have to find the right path and pay attention to your surroundings. Walking through historic areas of cities can make people feel less stressed and more energized — some researchers say even more so than walking through a park. Or you could simply focus on natural elements during your city walk. Trees in particular seem to make people more relaxed — even if they're on the street.

At-home tests of the gut's microbiome are trending, but doctors say the technology is getting ahead of medical knowledge. In many cases, there is no proven way to treat the imbalances that the tests claim to find. The companies and medical researchers say they hold great promise to one day personalize the treatment of complex gut-brain diseases. But much more clinical research and regulation is needed. The gut microbiome is complex and poorly understood. Growing evidence links changes in the gut to diseases like diabetes, liver disease, obesity and inflammatory bowel disease, but it's often unclear whether those changes cause, or result from, illness.