‘Tis The Season … For Gonorrhea? - FiveThirtyEight

As flu cases flatlined through January and February, Americans breathed a sigh of relief, kicked up our collective feet … and immediately realized we’d accidentally ingested norovirus and made a break for the restroom.

What is clear is that seasonality and the probable causes behind it will differ — even for the same disease — depending on things like geography, local culture and the development of medical technology.

Measles and chickenpox, for example, used to spread rampantly among children in the U.S., with yearly peaks happening when kids were in school, crammed together in their classroom petri dishes.

In some other countries, though, patterns of infection for those diseases have been tied to agriculture, Martinez said, with peaks that coincide with rural farmers congregating in population centers to sell their harvests.

Meanwhile, successful vaccination campaigns have meant that, even if measles and chickenpox do still crop up occasionally in this country, we no longer expect outbreaks every spring.

Back in 2015, during the Zika virus outbreak in South and Central America, women were being cautioned against getting pregnant, Martinez said, because of the way infection can harm fetuses, causing more babies to be born with microcephaly and developmental delays.