Cats may be susceptible to the highly lethal H5N1 bird flu virus, the UN Food and Agriculture Organization (FAO) says. Even so, they see no scientific evidence to suggest cats can transmit it to other cats or humans. Cats should not be killed as a control option, they say.
The FAO does recommend that in areas with H5N1 in poultry or wild birds, cats should be separated from infected birds until the danger passes. In commercial poultry premises cats should be kept indoors, away from the birds. There is no evidence to show cats transmit the virus.
The FAO says removing cats could lead to a surge in rodents such as rats and other agricultural pests that can transmit diseases to humans. Ever since the first human case of H5N1, linked to widespread poultry outbreaks in Viet Nam and Thailand, was reported in January 2004, UN health officials have warned that the virus could evolve into a human pandemic if it mutates into a form which could transmit easily between people.
In Indonesia there have been unconfirmed reports of H5N1 in scavenging cats. Those cats were sampled in near poultry markets in Java and Sumatra where outbreaks of bird flu had recently occurred.
This is not the first time that cats have been infected as previous incidents in Thailand, Iraq, Russia, the European Union and Turkey show. Cats can become infected by feeding on sick domestic or wild birds; they can develop severe to fatal disease and excrete the virus from the respiratory and digestive tracts.
“This raises some concern not only because cats could act as intermediary hosts in the spread of the H5N1 virus between species but also because growth in cats might help the H5N1 virus to adapt into a more highly infectious strain that could spark an influenza pandemic,” FAO Assistant Director-General Alexander Müller said.
Indonesian researchers say around 80 per cent of cats in outbreak areas were not infected. “This is rather encouraging because it indicates that cats are unlikely to constitute a reservoir of virus infection. Cats are more likely to be a dead-end host for the H5N1 virus,” FAO Animal Health Officer Peter Roeder said.
Researchers will continue to closely monitor the situation. “Any unusual mortality in cats should spark a suspicion of H5N1. Infection in cats could be an early warning signal for the virus. The observation of cats should therefore become part of surveillance systems in affected areas,” Mr. Roeder added.
FAO will start field studies in areas in Java where the H5N1 virus is prevalent and where cats have died to investigate their role in disease transmission. This research will be extended to other parts of Indonesia and elsewhere. [FAO]
More than 200 million birds died worldwide from either the virus or preventive culling in the current outbreak.
“We also need experimental studies to better understand the biology of H5N1 infection in cats, including most importantly the duration of virus shedding by infected animals,” Mr. Roeder said.
There have so far been 272 confirmed human cases worldwide, 166 of them fatal, the vast majority in South-East Asia.The highest death toll was recorded in Indonesia – 63 out of 81 cases. UN health officials are monitoring samples, looking for any mutation that could make the disease more easily transmissible in humans.
The so-called Spanish flu pandemic of 1918-1920 killed from 20 – 40 million people worldwide.