25 September 2006
Indonesia reports 48th patient, and 39th death (81% fatality rate), due to H5N1 avian flu virus in 2006 including use of recent WHO case definitions of H5N1 infection.
The World Health Organization (WHO) and Ministry of Health in Indonesia reported today the deaths of two children, ages 9 years and 11 years, due to H5N1 avian influenza virus infection. Since the initial patients were reported in a family living in Tangerang in July 2005, Indonesia has now reported a total of 67 persons with laboratory-confirmed H5N1 virus infection, of whom 51 (76%) have died. In this year so far, 39 of the 48 patients (81%) with H5N1-confirmed infection have died. The two most recent fatal infections with H5N1 virus have been linked to exposure to ill poultry.
Earlier this month, Indonesia reported to the WHO a total of four patients with retrospectively-confirmed H5N1 infection, based on laboratory criteria included in the August 29, 2006 WHO case definitions for human H5N1 infection. These four patients became ill on: June 24, 2005; November 25, 2005; March 4, 2006; and May 17, 2006.
The first of these four patients was an 8 year-old girl from Tangerang in Banten Province who was part of a family cluster reported to WHO in July 2005 and described on the WHO website July 21, 2005. The 38 year-old father of the family died of laboratory-confirmed H5N1 infection, and another 1 year-old daughter died of pneumonia illness consistent with H5N1 avian flu infection. An initial epidemiologic investigation did not find evidence of exposure to infected poultry, pigs, or other veterinary or environmental sources. There was also no known travel or other potential exposure to persons with H5N1 virus infection. Evaluation of 300 contacts of these family members in the summer of 2005 did not reveal any other H5N1 infections.
The WHO case definitions for H5N1 virus infections in humans follow a template similar to the one created by WHO, and used worldwide, for defining SARS coronavirus infection during the 2003 epidemic. It is also similar to the working case definitions for H5N1 infection used by the Thailand Ministry of Public Health, and posted on their website in 2004, during their initial outbreak of this virus. The August 29, 2006 WHO case definitions include four categories:
1. “Person under investigation”: any person public health officials are investigating for a possible H5N1 infection.
2. “Suspected H5N1 case”: Of note, requirements include unexplained acute LOWER respiratory illness with fever” and one or more potential H5N1-exposures in the SEVEN (7) DAYS prior to symptom onset.
3. “Probable H5N1 case”: requires meeting criteria for a “suspected case” plus radiographic evidence of acute pneumonia PLUS respiratory failure (hypoxemia, severe tachypnea), OR lab-confirmation of an influenza A type infection but insufficient lab evidence specifically of an H5N1 influenza A infection. Note: “Probable definition 2” is “ a person dying of an unexplained acute respiratory illness who is considered to be epidemiologically linked by time, place, and exposure to a probable or confirmed H5N1 case”.
4. “Confirmed H5N1 case”: requires meeting the criteria for a suspected or probable case plus any one of four types of laboratory results (e.g., (1) viral culture isolation, (2) PCR for H5 using two different PCR targets, (3) a four-fold or higher rise in neutralization antibody titer between acute an convalescent sera, (4) a single time point with two different positive antibody assays above a specified level or an H5 specific western blot result) “in a national, regional, or international laboratory whose H5N1 test results are accepted by WHO as confirmatory”.
Some have noted that initial diarrhea or neurologic presentations due to H5N1 infection, exposure more than seven (7) days prior to symptom onset, or asymptomatic H5N1 infection, are not part of these standardized case definitions. At the same time, however, WHO noted in this same August 29th document that “the case definitions are not intended to provide complete descriptions of disease in patients but rather to standardize reporting of cases” and that clinical judgment takes precedence in the care, triage and treatment of any patient who might have H5N1 infection. Specifically, WHO noted that “while most patients with H5N1 infection have presented with fever and lower respiratory complaints, the clinical spectrum is broad”.
To date, the number of persons reported who present to medical attention with neurological or intestinal symptoms without respiratory symptoms is small, and therefore the WHO standardized definitions are understandable.
At the same time, clinicians as well as public health officials must remain vigilant in considering H5N1 infection as the possible cause of neurologic or intestinal illness in persons who may have had H5N1 virus exposure. For the individual patient with serious H5N1 illness, therapy with oseltamivir (Tamiflu) or zanamivir (Relenza) typically needs to be given early in the course of the infection whenever possible, even while awaiting laboratory test results for H5N1 virus infection.
Daniel R. Lucey, MD, MPH
Director, Center for Biologic Counterterrorism and Emerging Diseases
EROne Institutes, Department of Emergency Medicine
Washington Hospital Center
Co-Director, Master of Science Program, Biohazardous Threat Agents and Emerging Infectious Diseases, Department of Microbiology and Immunology
Georgetown University School of Medicine, Washington, DC
Website: www.BePast.org e-mail:Daniel.R.Lucey@Medstar.net