Mycoplasma pneumoniae infection in Hong Kong--clinical and epidemiological features during an epidemic.

An epidemic of infection due to Mycoplasma pneumoniae occurred in Hong Kong in 1986-1988. One hundred and seventy-nine cases were identified at the Prince of Wales Hospital over this period. Clinically significant infection predominantly affected children under 12 years, with 32% of all infections occurring in children aged between 6 and 11 years, and 39% in children between 1 and 5 years. Ninety-seven percent of childhood infections were respiratory in nature, the other 4 presentations were neuropsychiatric. Adequate information was available on 36 of the 43 subjects over 12 years. One teenager presented with acute psychosis; all other cases (35) were respiratory. In these cases cough was universal, and fever was present in 34 (97%). A variety of non-specific symptoms (rigors/chills, malaise, headache, sore throat, sweating) were frequently noted. Sputum production was documented in 75% of cases, and was frequently purulent. Radiological consolidation was very common (95% of cases), but resolved fully after 4 weeks. Complications were rare and included acute pericarditis in 1 patient and haemolysis in another, and both patients recovered subsequently. Clinical recovery was otherwise rapid and complete in all other patients. Persisting dry cough was the only symptom documented at follow-up. Although infection due to M. pneumoniae in an ethnic Chinese population appears similar to that described in other populations, a higher incidence in younger children was recorded in this study.