All infectious diseases likely to be seasonal

A new study conducted by a researcher at the Columbia University Mailman School of Public Health suggests that all infectious diseases are caused by seasonal elements.

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Environmental Health Sciences Professor Micaela Martinez has collected data on 69 infectious diseases from the US Centers for Disease Control and Prevention, the World Health Organization and peer-reviewed journal articles. . She then mapped the time of year when epidemics tended to occur, ranging from common infections to rare tropical diseases.

As reported in the newspaper PLOS pathogensShe found that in a given year influenza outbreaks occurred in winter, chickenpox in spring, and polio and gonorrhea in summer.

The study describes four main factors that influence the seasonal influence on the disease. Seasonal flu is influenced by environmental factors such as humidity and temperature. During vector-borne diseases such as Zika, the environment affects the proliferation of mosquitoes.

Host behaviors also play a role. The fact that children are close to each other during the school year, for example, is a factor involved in the spread of measles.

Ecological factors are also involved. For example, the bacterium responsible for cholera is kept in water fed with algae.

Being aware of these seasonal epidemic factors could help public health officials intervene to prevent the spread of the disease. They could set up a strategy for, for example, the survival of the bacteria responsible for cholera in water bodies filled with algae.

Seasonal biological rhythms such as those that control the migration and hibernation of animals are another potential factor in diseases such as polio. However, this possibility requires additional research.

Martinez said that seasonality is a powerful and universal feature of infectious diseases, but that the scientific community has largely ignored it when considering the majority of infections.

Much work is still needed to understand the factors that determine the seasonality of diseases and to understand how we can use them to design interventions to prevent epidemics and treat chronic infections.

Professor Micaela Martinez, author of the study