H5N1 Culling Delays Increase Pandemic Concerns in India

Recombinomics Commentary 20:05
December 7, 2008

The dreaded bird flu or avian influenza, which was confirmed at a village of Hajo in Kamrup district on November 27, has since spread to a number of new areas of several districts. This is a matter of grave concern, as the efforts initiated at containing the disease have not been successful.

First, the authorities were late in having the abnormal death of fowls in large numbers – reported since November 21 -- confirmed as bird flu.

Then, allegations have also been made about the unscientific disposal of the remains of the dead birds

The above comments are from a recent Assam Tribune editorial. The number of confirmed districts has grown to six (see satellite map), and media reports indicate the daily confirmations are from samples collected 10 days ago, raising concerns that the spread is well beyond the confirmed locations.

The sequence of events is similar to those of West Bengal a year earlier. Testing was limited and delayed, resulting in the start of culling long after birds began to die. Eventually, culling was initiated in regions with excessive poultry deaths, followed by culling in regions bordering West Bengal. However, the spread was great in both West Bengal and adjacent Bangladesh, resulting in the largest outbreaks reported to date.

However, these culling delays can allow spread to snowball though additional infections of villagers as well as resident wild birds and mammals who eat the birds. A year ago in West Bengal, villagers were either eating the dead birds, or improperly disposing of them, creating opportunities for further H5N1 spread. Moreover, vouchers below Market value led to hiding of birds or transport to other areas. Although West Bengal borders were sealed, the H5N1 rapidly spread.

In Assam, the spread has also been rapid, even though the outbreaks began a month earlier when the temperature was warmer. This rapid spread may have created excessive birds deaths in other areas. India is already blaming Bangladesh from spread, and other states have issued alerts, even though they are not adjacent to the confirmed outbreaks.

Thus, the current extent of spread remains unclear, but the shortage of culling groups and delayed culling remain causes of concern. In addition to the spread, the delays in controlling the spread increase the number of mammals infected by H5N1, which increases the likelihood for selection of genetic changes that will increase the efficiency of transmission to humans.

Last season one H5N1 human case was confirmed in Bangladesh, but many additional unreported cases were likely.

Repeated poorly controlled outbreaks in this region continue to increase the likelihood of a catastrophic pandemic.