The U.S. Open champion confirmed that his recent illness might be a mild case of Dengue fever, which is transmitted by mosquito bites.

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Symptoms include mild headaches, muscle pain, fever, a persistent cough and sometimes vomiting and diarrhoea.

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At most, a child may experience mild reactions to the vaccine, including swelling at the injection site, itching, low-grade fever or restlessness, Martin said.

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