How the weather and the seasons affect the spread of Strep throat.

Strep throat is the most frequent form of bacterial sore throat. It's estimated that about 30% of all sore throat cases between the age of five and 15 years old are attributed to Strep throat. Strep throat is caused by a bacteria called Streptococcus pyogenes, which belongs to the group of Group A beta hemolytic Streptococci (GAS). Strep throat is a simple infection that can be treated with oral antibiotics. The symptoms may even resolve without treatment in about a week. However, without antibiotic therapy, there’s an increased risk of complications like Rheumatic heart disease, severe inflammation in the kidneys, and arthritis. 


Typically, cold weather and crowded indoor spaces, like schools, dorms, and office buildings have been linked with the spread of Strep throat infections. Studies have shown that higher rates of strep throat cases are typically reported in late winter and early spring, with some variations in seasonality across the globe. In the northern hemisphere, the peaks of strep throat infections in the United States are in the fall (usually in October) and winter. Reports from the United Kingdom show two peaks for strep throat infections, an initial peak in January and another strong peak in March. Around the globe, the infection typically peaks in both fall/winter and spring. 


The school environment is a well-known factor in the transmission of infectious diseases, due to the sheer number of children in a space, and constant sharing of equipment and supplies. Strep throat primarily affects school-aged children, with most kids experiencing an infection every one or two years. 


One study found that in a school outbreak, Strep throat was identified in 61% of the school kids in just 16 days after the first case was reported. And closing the school for a period of between eight and 14 days decreased the rate of Strep throat infections significantly. Besides schools, crowding in households and military facilities also increases the chances of catching a Strep throat infection. 


Temperature also plays an important role in the seasonality of strep throat infection. Decreasing the body temperature makes Streptococcus pyogenes more virulent and vice versa. Moreover, temperature also impacts the growth of strep throat bacteria, with the optimum temperature for its growth ranging from 84 to 98.6 degrees Fahrenheit (29-27°C), which might explain the sharp peak in Strep throat cases during early springtime. Sun exposure also is an important factor, since the ultraviolet (UV) radiation coming from the sun has shown to kill bacteria. Additionally, UV light indirectly boosts the immune system by increasing the levels of Vitamin D in the body, which helps fight against Strep throat infections, among other common illnesses like the cold or flu.

Strep throat is so common, especially with kids, it usually feels more like a “when” they’ll get it, rather than an “if.” From that first scratchy feeling in their throat to full-on Strep throat symptoms, it’s important to get a confirmed diagnosis so you can start them on the path to recovery. Checkable medical makes testing for Strep easy, all from the comfort of your own home.