This case highlights the difficulties associated with the differential diagnosis of pulmonary symptoms in patients with pre-existing disease in extreme environmental conditions. A 58-year-old man with child-onset allergic asthma developed dyspnoea and an acute non-productive cough during a trekking expedition on Mount Kilimanjaro (5,895 m) in Tanzania. The symptoms were initially believed to be associated with the high altitude exposure (high altitude pulmonary edema [HAPE] or high altitude cough) or his pre-existing asthma, exacerbated by previous dust exposure during an overland car ride. However, he was later diagnosed correctly with a re-infection with Bordetella pertussis. Pertussis is a highly communicable disease with potentially serious medical consequences that could have affected all of the expedition members. The effectiveness of a pertussis vaccine declines four to 12 years after the vaccination. Thus, it is suggested that the status of immunization against pertussis should be checked along with those of other infections prior to travel.
