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Biosecurity BriefingIndonesia Publishes Study on its H5N1 Cases and Factors Linked to MortalityBy Crystal Franco, August 25, 2008 On August 15, 2008, The Lancet released a study in its early online publication describing the factors associated with H5N1 case fatality in Indonesia; those factors include symptoms, time to hospitalization, time to initiation of antiviral treatment, and several others. The authors, who are officials from the Indonesia Health Ministry and the World Health Organization (WHO), concluded that better diagnostic methods, faster H5N1 case recognition, and better case management would likely lead to a lower mortality rate, because these improvements would give healthcare providers the opportunity to administer antiviral medications to patients at an earlier stage of disease.1 Indonesia has developed a surveillance and patient referral system for human H5N1 infections based on WHO H5N1 case definitions. Health officers are trained to identify cases based on case definitions, conduct preliminary epidemiologic investigation of suspected cases, and take reliable patient samples for confirmatory testing at the labs. Suspected cases of H5N1 are to be sent immediately to an avian influenza referral hospital, which is at most within a day’s travel by land.1 There are currently 44 hospitals in country, and that number is being increased to 100. Since its first reported case in 2005, Indonesia has had the highest number of human cases of H5N1 in the world, with 127 cases confirmed via RT-PCR by WHO reference laboratories in Hong Kong and U.S. Centers for Disease Control and Prevention laboratories in Atlanta (from 2005 to 2007), or by two WHO-accepted national laboratories in Indonesia (after 2007). Of these 127 confirmed infections, 103 (81%) have been fatal.1 The authors note a statistically significant increase in the case fatality rate from 2005 to 2007, with fatalities increasing from 65% in 2005, to 81.8% in 2006, to 86.8% in 2007, with a slight drop to 80% in case fatality through February 2, 2008. Of the 127 patients confirmed to have H5N1, 122 were hospitalized, with a median time to hospitalization of 6 days (range 1-16 days). Of the 122 patients hospitalized, 121 (99%) had fever, 107 (88%) had cough, and 103 (84%) had dyspnea upon reaching the hospital. However, for the first 2 days of illness, symptoms were non-specific, and not all patients displayed all symptoms.1 Oseltamivir was given to 88 (69%) patients suspected of having influenza. However, some H5N1 infections were initially misdiagnosed as pneumonia or other respiratory illnesses. In those who received antiviral therapy, median time from symptom onset to initiation of treatment was 7 days (range of 0-21 days). Those patients who received treatment within 2 days of symptom onset had a significantly higher survival rate than those who received treatment 5 or more days following onset of symptoms.1 Clustering was identified as one factor linked to case fatality. Defined as “two or more confirmed cases epidemiologically linked by time and place,” 11 clusters were identified, with a total of 28 patients among them (2 to 7 individuals identified in each cluster). All of the clusters occurred among blood relatives, with a median age of 18 years. In contrast, the median age for non-clustered cases was 22 years. Mortality was lower in clustered cases, which may be due to earlier recognition and earlier initiation of antiviral treatment; oseltamivir was often started within 5 days following onset of symptoms in clustered cases vs. 8 days for non-clustered cases.1 The authors conclude that both early identification of H5N1 cases in the community and early treatment of patients in hospital are important to lowering mortality rate. They recommend increased training for community healthcare workers in early H5N1 case management; supplying healthcare workers in the field with stocks of oseltamivir; and increased surveillance of both avian and human H5N1 infections in Indonesia.1 References
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