This type of infectious illness are second only to diarrheoa as a cause of illness in travellers. Certain situations encountered when travelling place travellers at an increased risk of acquiring a respiratory infection.
Many travellers spend long periods of time in crowded conditions such as airports, hotels etc.
These places provide ideal conditions for spreading many acute respiratory infections like common colds and influenza. Dry aircraft cabins atmospheres and smoking more than usual, even passively, exposure to new allergens and city air pollution will all contribute to respiratory symptoms. Influenza is most common in the southern hemisphere during their winter season, which is summer in the northern hemisphere and visa-versa. Vaccination should be considered for those at risk of serious disease. Legionnaires disease has been linked to contaminated water used in water cooled air-conditioning systems and sometimes showers.