Web Exclusive: H5N1 hot spots not reporting outbreaks
H5N1 infection of poultry and captive or wild birds has now been detected in 60 countries.
H5N1 is a zoonosis (passed from animals to people) but transmission to humans has proved inefficient and relatively rare. In spite of some human disease clusters including eight members of one family in Indonesia, there is little incontrovertible evidence of human-to-human transmission. According to CIDRAP, there have been no samples available to test or virus particles in patients were genetically the same as those found in local poultry.
The only example of human-to-human transmission for which scientists are sure is the case of a 10-year-old Indonesian boy who passed the altered virus onto his father. Detection of the altered strain in the boy and his father was evidence of direct transmission.
Of the 60 countries recording H5N1, only two or three are regarded potential ‘hot spots’ for mutation and/or re-assortment of the virus into a strain that moves efficiently from poultry to people and then transmits with ease in the human population. Indonesia and Egypt are notifying human cases on a regular basis with 6 and 11, respectively, for 2007. Nigeria announced its first human case this year although experts believe many others may have been missed.
The Daily Update on Avian Influenza provided by OIE (World Organisation for Animal Health) gives latest reported outbreaks for Indonesia and Egypt as August 2006 and December 2006, respectively. The last reported outbreak for Nigeria was March 2006.
OIE may not be informed straightaway but other countries experiencing potentially serious problems are identifying and documenting outbreaks and sending relevant information to OIE without delay. Laos which confirmed its first human cases this year has the last poultry outbreak documented as 28 February 2007. Vietnam and Thailand still experience outbreaks in poultry but have largely got on top of H5N1. Thailand had 25 human cases from 2004-2006 and Viet Nam 93 with none since 2005, but these countries report their most recent outbreaks in poultry as 3 March 2007 and 19 March 2007, respectively.
It is suspected that Indonesia, Egypt and Nigeria are clearly not reporting outbreaks in poultry, or perhaps not recording, finding or even seeking avian sources of H5N1 causing increasingly high and high-profile human infection and death. H5N1 reservoirs in poultry must be identified, documented and dealt with or else these countries will be reporting human cases on a regular basis for a long time to come.