If you develop difficulty breathing or shortness of breath, chest pain or abdominal pain, sudden dizziness, confusion or have persistent vomiting, you should seek medical attention immediately.

FORBES: 2013 Flu Season: How to Protect Yourself

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

BBC: Legionnaires' Disease bacteria

Older children and adults who have whooping cough often appear to have a bad cold or persistent cough that can be so severe that it causes vomiting.

CNN: Can breast-feeding prevent whooping cough?