December 16, 1997
Up to 16 December 1997, seven cases of influenza A (H5N1) were discovered in Hong Kong. The first case was discovered in August and the other six cases were found in November and December 1997.
Four children and three adult were affected (age 2-54, 4 male 3 female). All of them enjoyed good past health except one child with ventricular septal defect. The initial clinical presentation was similar to typical influenza, with fever of acute onset, cough, sore throat and running nose. Four cases suffered a rapid downhill course with development of viral pneumonia, adult respiratory distress syndrome and renal failure. Two patients have died and three are receiving treatment in hospital. These cases probably represent a more severe form of the disease as they were taken from hospital in-patients. It is believed that like other types of influenza, most of the patients would make a full recovery.
It was noted that one fatal case had history of delayed treatment from travel. One fatal case was complicated by Reye's syndrome, and had a history of taking aspirin. In one of the severely ill cases, there was delayed hospitalization due to change of the attending doctor.
Influenza A (H5N1) was known previously to infect birds only, and these were the first cases in which humans were affected. The Department of Health is working closely with the Centres for Disease Control (CDC), Atlanta and local experts to ascertain the mode of transmission of the virus and determine its public health impact. Investigations showed no evidence that the four cases were linked or shared a common source of infection. Man-to-man transmission is not yet proven, but further investigations are being conducted to examine this possibility.
The data gathered so far suggest that influenza A (H5N1) has similar clinical presentation as other influenza viruses. The appropriate management should consist of adequate rest, fluid replacement and antipyretic as necessary. Aspirin should be avoided in children . If there are signs of complications such as pneumonia, the patient should be hospitalised. The use of specific anti-viral therapy such as amantadine is discussed in the attached note .
Appropriate counselling on prevention of influenza should be given to patients and members of general public. Important messages include no smoking, a balanced diet, regular exercise and adequate rest to maintain body immunity. Observation of good personal hygiene and maintaining good ventilation are also useful.
* This advice will be updated when further information becomes available.