Cough
When a sudden expulsion of air is seen to be happening through the large breathing passages which later helps in clearing the fluids, irritants, foreign particles and microbes. It is usually a protective reflex in which coughing can be recurring as a part of cough reflex .

Frequent coughing generally specifies/shows whether the disease is present or not. From an evolutionary perspective, a lot of viruses and bacteria impose a good effect leading the host to cough, which later on spreads the disease to the new hosts.
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