https://www.scientificamerican.com/article/to-every-pathogen-there-is-a-season/

Everyone knows flu strikes most often during wintertime, but new research indicates a number of other infectious diseases are seasonal, too. Chicken pox often peaks in spring. Sexually transmitted diseases tend to strike most often in the summer, at least in the U.S. And bacterial pneumonia is most common in midwinter, according to a study of 69 infectious diseases, published Thursday in PLOS Pathogens.

Lead author Micaela Elvira Martinez says she had expected to find acute infections, ranging from malaria to polio, had seasonal peaks. What she had not anticipated was a similar pattern in chronic ones—including HIV. “I was very surprised,” says Martinez, an assistant professor at Columbia University’s Mailman School of Public Health.