8 October 2008

Pakistan 2007: Family cluster of 5 brothers with H5N1 Avian Flu infection includes the full clinical spectrum from fatalities to the (rare) asymptomatic household contact case=

= This week's "Weekly Epidemiological Record" of the World Health Organization provides a detailed description of the investigation of a family cluster in Pakistan last October-November (2007) of H5= N1 avian influenza infection (www.who.int/wer 3 October 2008; No. 40. p 359-364). Several of the salient features of this cluster include:=

= 1. The index case was most likely infected during culling of H5N1-infected pou= ltry (without PPE) in the "poultry-belt" of the North-West Fronti= er Province (NWFP) of P= akistan. He developed a fever on October 29, 2007. On 2 November he travelled by public transport the four hours to his family's home in Peshawar, where 5 brothers and 2 sisters lived. WHO stated that he is "the first person to = have documented influenza A (H5N1) disease following occupational exposure during poultry culling" (p. 363).

= 2. Four of his brothers (Cases 2-5) became ill with probable or lab-confirmed = H5N1 infection. These cases included a 33 year-old brother who was asymptomatic, but had an H5-PCR+ throat swab and a positive H5 antibody = test. This is a rarely-documented event, and the WHO repo= rt did not cite a single other example of asymptomatic seroconversion in house= hold contacts of H5N1 patients, except during the 1997 Hong Kong H5N1 initi= al outbreak (J Infect Dis 1999; 180:1763-1770). =

= 3. None of the four brothers had exposure to poultry.  All had prolo= nged close contact with the index case and/or one another. Based on contact exposures between the brothers, and estimated incubation periods, = ;the multiple investigator teams determined that human= -to-human transmission occurred for "3 generations of transmission",= but it was "not sustained in the community" beyond this one family (p. 364).

= 4. The full clinical spectrum was seen in Cases 1-5, including:=

=       a.. Fatal infection: Case 2 and Case 3.=

=       b. Recovery with intensive care (ICU) (for 9 days). Case 1 (index)=

=       c. Recovery without intensive care: Case 4 =

=            (Oseltami= vir ("Tamiflu" was begun one day after fever started).=

=       d. Asymptomatic lab-confirmed infection.

= Daniel R. Lucey, MD, MPH

= EROne Institutes, Washington Hospital Center=

= Adjunct Professor of Microbiology and Immunology

Georgetown University Medical Center=

Washington, D.C.<= /st1:place>=

website for this posting: www.BePast.org= =

= e-mail:DRL23@Georgetown.edu=