Commentary
H5N1 Confirmation Delays in Bangladesh Increase Concerns
Recombinomics Commentary 16:24
May 23, 2008
The toddler became ill in January this year, and has since made a full recovery, said Hartl. Although the health authorities in Bangladesh reported the suspected case straight away, it took time for a sample from the baby to be sent and tested in the US, he said.
The above comments on the first confirmed H5N1 in Bangladesh raises serious surveillance concerns. The confirmed patient was a child with a relatively mild case of H5N1 in an overcrowded Dhaka slum with no clear connection to poultry. In January, 2008 H5N1 outbreaks in Bangladesh and West Bengal were widespread, and there was little doubt that human and poultry H5N1 were being under reported in both countries.
In West Bengal, villagers had been eating H5N1 infected birds since December, 2007 and were developing bird flu symptoms. However, India was using a “watchful waiting” approach, which kept the sick villagers under observation, but did not test. This lack of testing extended to wild birds that died in proximity to the dead poultry and delayed testing of poultry which led to delayed culling.
In Bangladesh H5N1 had been reported in 2007, but there were media reports suggesting the H5N1 in birds were being under-reported. By January reporting and culling began to increase, but those increases were accompanied by reports of wild birds dying and confirmation of H5N1 in birds literally falling out of trees in major population centers. H5N1 in crows was confirmed in densely populated Chittagong, and crows also began dying in Dhaka in late January, early February, when the above case was hospitalized. There were also reports of dead wild birds in Calcutta as well as H5N1 confirmed poultry in the suburbs.
The confirmed case in Bangladesh had tested positive for influenza A, but initial tests for H5 were negative. Consequently, the respiratory disease was not treated by Tamiflu, suggesting the infection was relatively mild although the child was hospitalized fro 14 days.
Mild H5N1 is of great concern because patients are more likely to remain mobile and spread the infection. Moreover, mild cases are less likely to visit physicians, be tested, or test positive when tested.
Thus, a mild case of H5N1 in a crowded slum in Dhaka, Bangladesh in the absence of a poultry connection is a nightmare scenario, yet confirmation came almost four months after admission.
These delays have extended a recent trend in human cases. In Pakistan, one of the largest transmission chains began in October, 2007, but was not reported until December, 2007. The reports were made after the index case fatality infected one of his brothers, who then infected two more brothers. There were no reports until a after a second brother died. By then the samples has largely degraded and only the second fatal case was confirmed. Two surviving brothers were recently confirmed based on H5 antibody increases, but this cluster was also associated with a significant delay.
In Indonesia there have been clusters linked to three of the four recently confirmed cases, but those clusters are denied even after a cluster member has been H5N1 confirmed.
Similarly, a soldier in South Korea was denied after he had tested H5 positive in two or three lab tests. The soldier had pneumonia and lost consciousness after culling H5N1 infected poultry, yet was said to be negative because of a failure to confirm N1.
Testing and reporting of H5N1 in birds is also deficient. H5 in dead geese on a farm on Prince Edward Island is allowed to degrade prior to shipment for independent confirmation and North America is declared H5N1 free.
Recent H5N1 positive whooper swans in Japan are reported after initially testing negative.
Six travelers on a Canada train are said to be influenza A negative based on a rapid test, yet subsequently test positive for seasonal flu.
This long list of false negatives and delayed reporting creates a false sense of security regarding the spread of H5N1 in avian and human populations, which can be hazardous to the world’s health.
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