The rising outbreak of bird flu both in birds and humans has renewed fears of a pandemic that could kill millions of people. Highly pathogenic H5N1 strain of bird flu virus is gradually increasing its ability to spread efficiently and substantially among humans.
It has already met all prerequisites for the outbreak of a pandemic. The World Health Organisation (WHO) states this condition as “Pandemic Alert Period”. High officials of WHO recently urged governments to act swiftly to control the spread of bird flu warning that the world is in grave danger of a deadly pandemic triggered by the virus.
Since its first detection in 2003, there are 399 people reported to have contracted the illness, of which 251 have died across the world, according to WHO. Most of theses cases were linked with close contacts with sick birds. Experts have warned the H5N1 virus could become far deadlier if it mutates into a form that can be easily transmitted among humans.
The virus can improve its transmissibility among humans through two principal mechanisms. The first is a “reassortment” event, in which genetic material is exchanged between human and avian viruses during co-infection of a human. Reassortment could result in a fully transmissible pandemic virus, announced by a sudden surge of cases with explosive spread.
The second mechanism is a more gradual process of adaptive mutation, whereby the capability of the virus to bind to human cells increases during subsequent infections of humans. Adaptive mutation, expressed initially as small clusters of human cases with some evidence of human-to-human transmission, would probably give the world some time to take defensive action, if detected sufficiently early. The virus may mutate or change into a form that passes easily from human to human, causing an epidemic that could spread very rapidly in our densely populated country.
So far, one baby boy have tested positive in Bangladesh in 2008 and he was one of the few luckiest cases who recovered from this deadly virus. But Bangladeshis are at great risk as 4 million people are directly or indirectly associated with poultry farming.
Avian influenza has already spread through 47 out of 64 districts in Bangladesh. This signifies that it is a matter of time to get large number of human cases in near future.
Dr. Shigeru Omi, the WHO’s Western Pacific regional director said, “We at WHO believe that the world is now in the gravest possible danger of a pandemic and the world is now overdue for an influenza pandemic, since mass epidemics have occurred every 20 to 30 years. It has been nearly 40 years since the last one.”
Experts identified one of the biggest challenges in controlling avian flu is in altering traditional farming practices in Asia where animals live in close, often unsanitary quarters with people. Taking extra precaution like wearing protective devices like gloves, glasses, hand washing with simple soap and hot water after handling chickens and birds, eating properly cooked meat and egg (above 70°C) can reduce the transmission to a significant level.
We often forget to wash the egg before handling, disinfecting the slaughtering places or to dispose faeces of the infected birds loaded with the H5N1 properly. These pose a great threat for the spread of the virus along with the migratory routes of wild waterfowl.
Diagnostic tools and surveillance systems should be improved immediately for early warnings and to detect the maximum human cases. Vaccination and early treatment has a great role in slowing the process of spread and preventing a pandemic, according to the experts.
The H5N1 virus has spread in more than 60 countries and caused at least 6,500 poultry outbreaks since 2003. This is why coordinated movement is badly needed to work on a pandemic preparedness plan so that even in an emergency we can provide basic public health support.
Dr Md Rajib Hossain
Source: The Daily Star, January 24, 2008