It's common to see trends in parasitic infections in the same geographical area and environment where people are exposed to the same water, soil, and air routes of transmission, particularly in the summer months, often peaking when outdoor and water temperatures are at their highest.
The distribution and prevalence of intestinal parasites differ from country to country and even regionally within countries because of environmental, social, and geographical factors.
Studies have shown that age, host biological sex, poor sanitation, water, hygiene, geographical location, contact with animals, and seasonal variations are major risk factors in the transmission of parasitic infections, especially protozoan infections (e.g., Entameoba histolytica, giardia lamblia, cryptosporidiosis).
Summer months show the highest incidence of parasitic infection compared to winter months. Bacterial infections are also influenced by seasonal variations.