23 January 2006
WHO updates facts on H5N1 virus, including use of a 7-day incubation period for monitoring contacts, and consideration of 7-10 day therapy with oseltamivir (Tamiflu) for severe infection.
This weekend the WHO posted on their website a five-page document with important updates on their “Fact sheet” for avian influenza (“bird flu”).
The WHO update includes eight (8) topics: the disease in birds, the role of migratory birds, countries affected by outbreaks in birds, the disease in humans, history and epidemiology, assessment of possible cases, clinical features, and countries with human cases.
Eight (8) important clinical features warrant emphasis:
1. “The incubation period for H5N1 avian influenza may be longer than that for normal seasonal influenza, which is around 2 or 3 days. Current data for H5N1 infection indicate an incubation period ranging from 2 to 8 days and possibly as long as 17 days...WHO currently recommends than an incubation period of 7 days be used for field investigations and the monitoring of patient contacts.”
2. “Watery diarrhea without blood appears to be more common in H5N1 avian influenza than in normal seasonal influenza.”
3. “On present evidence, difficulty in breathing develops around 5 days following the first symptoms…most recently, blood-tinged respiratory secretions have been observed in Turkey.”
4. “Another common feature is multiorgan dysfunction, notably involving the kidney and heart.”
5. “Common laboratory abnormalities include lymphopenia, leucopenia, elevated aminotransferases, and mild-to-moderate thrombocytopenia with some instances of disseminated intravascular coagulation”.
6. “As the duration of viral replication may be prolonged in cases of H5N1 infection, clinicians should consider increasing the duration of treatment to 7 to 10 days in patients who are not showing a clinical response.”
7. “In cases of severe infection with the H5N1 virus, clinicians may need to consider increasing the recommended daily dose or the duration of treatment, keeping in mind that doses above 300mg per day are associated with increased side effects.”
8. “In severely ill H5N1 patients or in patients with severe gastrointestinal symptoms, drug absorption may be impaired. This possibility should be considered when managing these patients.”
With the additional of two more H5N1-infected young people from Indonesia today, the total number of WHO-lab confirmed patients has now reached 151 with 82 fatalities (54%). The update on clinical, epidemiologic, and avian-veterinary issues by the WHO is timely and very helpful.
A request to the WHO:
A detailed clinical, epidemiologic, and demographic summary of the all lab-confirmed patients, including recent ones from Turkey, Indonesia, and China would be very valuable and greatly appreciated by clinicians and hospital and public health planners worldwide.
For example, how often do clinically significant kidney and cardiac manifestations of H5N1 infection, mentioned in this WHO update, occur? How many patients have received oseltamivir (Tamiflu) within 48 hours of onset of illness, how many within 72, 96, or 120 hours of onset of illness, what data is available for adjunctive use of steroids for H5N1 lung disease (steroids were also used for SARS pneumonia as that epidemic unfolded), how many patients have been placed on ventilators, and of those how many have survived, what evidence is there regarding efficacy of N-95 respirators or surgical masks to prevent H5N1 infection, what data is there regarding patients with H5N1 infection who have received 7-10 days of oseltamivir therapy or 300 mg per day rather than the standard 150 mg (75 mg every 12 hours) for seasonal influenza, and other such key clinical issues that would benefit clinicians and planners everywhere?
Daniel R. Lucey, MD, MPH
Director, Center for Biologic Counterterrorism and Emerging Diseases
EROne Institutes, Washington Hospital Center
Co-Director, Master of Science (M.S.) Program in Biohazardous Threat Agents and Emerging Infectious Diseases, Georgetown Medical School
Email: Daniel.R.Lucey@Medstar.net; cell: 202-299-4398