Summer changes epidemiology.
Not because diseases follow the calendar, but because our behaviour and environment do.
People travel more. We spend more time outdoors. Windows stay open. Mosquitoes and ticks may have more opportunities to interact with humans. Food is transported, prepared and stored under different conditions. Large gatherings bring people together in new combinations.
The result is a changing pattern of exposure.
For some infections, summer can increase transmission opportunities.
For others, the risk may shift geographically or towards particular groups.
And some diseases do not disappear at all. Their surveillance simply becomes harder when healthcare-seeking behaviour, testing practices and population movement change.
This is why “summer disease” is not really a useful epidemiological category.
A better question is:
What changed in the pathways through which people were exposed?
That question takes us from seasonality to epidemiology.
Exposure → transmission → infection → healthcare seeking → diagnosis → reporting.
Every step can be affected by the season.
And by August, epidemiologists are already watching those patterns closely — because the next seasonal shift is approaching.