Scientists have discovered that the seasons appear to have a profound effect on how human genes work.
Notice how there seems to a marked increase in ailments during the cold, rainy season?
Apparently it's no coincidence as scientists have discovered that the seasons appear to have a profound effect on how human genes work, and in turn susceptibility to certain diseases.
According to a study in Nature Communications, it was discovered that genes involved with immunity were more active in cold months.
Thus, while this helps fight off viruses such as flu, it may trigger or worsen conditions, such as arthritis, where the body attacks itself.
Blood and tissue samples from more than 16,000 people living around the world were studied by a team of researchers who subsequently arrived at the above conclusion.
According to the study, of the 22,000 genes they studied, which is nearly all the genes humans possess, a quarter showed clear signs of seasonal variation.
The gene changes that interested the researchers the most were ones involved with immunity and, specifically, inflammation.
During cold, winter months which is December to February for people living north of the equator and June to August for those in the southern hemisphere (under which Nigeria falls) - these genes were more active.
The study further showed that there was a different patter for people living close to the equator, where the temperatures are fairly high all year round. Thus, inflammation was linked to the rainy season when diseases such as malaria are more prevalent.
But in Iceland, where it is cold most of the time, they found fewer seasonal changes.
This, according to Prof John Todd, one of the study authors, who is based at Cambridge University, United Kingdom, explains why people were prone to certain diseases at particular times of year.
Consequently, conditions such as rheumatoid arthritis, type-1 diabetes and heart disease, which peak in the winter in countries such as the UK owing to inflamation.
However, Prof Todd said it was hard to tease out precisely what was happening, since many factors influenced an individual's chance of developing a disease.
Tim Spector, professor of genetic epidemiology at King's College London also added that gut microbes were affected by change in seasons and "could be driving these changes because of seasonal changes in diet."
Metabolism was also influenced by seasonal changes, according to the research.