Aug 22, 2005 (CIDRAP News) – Wildlife researchers and Mongolian officials have reported increasing evidence that H5N1 avian influenza has infected wild birds in Mongolia, though findings are not yet conclusive.
The Wildlife Conservation Society (WCS) announced last week that preliminary tests revealed the virus in 1 of about 100 wild birds found dead earlier this month at Erhel Lake in Mongolia. But samples from close to 140 live birds at the lake tested negative, the group said.
In addition, Mongolian officials reported to the World Organization for Animal Health (OIE) on Aug 19 that three wild birds from the same site had tested positive for an H5 virus. The results of further testing to fully characterize the virus were still awaited, the report said.
The WCS said two of its field veterinarians, Dr. William Karesh and Dr. Martin Gilbert, visited Erhel Lake with Mongolian scientists and health officials shortly after the suspected cases of avian flu were reported there. They found about 100 dead birds and observed more than 6,500 healthy birds of 55 species, according to a WCS news release.
The team sent samples from 774 birds to the US Department of Agriculture's Southeast Poultry Research Laboratory in Athens, Ga., for analysis, the WCS said. As of Aug 18, preliminary tests (involving reverse-transcriptase polymerase chain reaction ) revealed H5N1 virus in one dead whooper swan, the group reported.
Samples from 30 live whooper swans from the same site and another nearby lake were free of the virus, the statement said. Other live birds that tested negative included 60 ruddy shelducks, 24 bar-headed geese, and 25 black-headed gulls.
The WCS called the finding at Erhel Lake "the first instance of this viral strain [H5N1] occurring in wild migratory birds with no apparent contact to domestic poultry or waterfowl." Outbreaks in wild birds have usually occurred near outbreaks in poultry or in regions where contact with infected poultry could not be ruled out, but Mongolia has few domestic birds, the group said.
According to the release, Gilbert said the percentage of sick and dying birds at Erhel Lake was "minuscule," suggesting that "either the virus had little effect on the birds or that very few were actually infected by the bug."
The possible cases in Mongolia follow recent poultry outbreaks of H5N1 in six districts of southwestern Siberia, reaching to the Ural Mountains, and in at least one area of northern Kazakhstan. A large H5N1 outbreak in wild birds occurred last spring at Qinghai Lake in central China, which borders Mongolia on the south.
Elsewhere, another poultry outbreak of avian flu was reported today in Japan, where an H5N2 outbreak surfaced on one chicken farm last week. An Agence France-Presse (AFP) report identified the latest outbreak only as an H5 virus.
The outbreak occurred at a large farm in Ishioka, 50 miles northeast of Tokyo, where more than 1.1 million chickens are kept in 12 houses, AFP reported. The story said the farm is one of three that supply chickens to the farm where avian flu turned up last week.
Health officials plan to kill all 100,000 chickens in the building where the outbreak was found, the report said. Japan had four outbreaks of H5N1 avian flu last year but has reported none so far this year.
In Russia, the first avian flu outbreak on a large poultry farm was reported today, according to the Russian news agency RIA Novosti. The disease was reported in the Omsk region, one of the six areas where outbreaks have been reported on small farms in recent weeks.
A Russian official told the OIE on Aug 20 that poultry deaths in the outbreaks had not exceeded about 5% of the total flock in any given area, thanks to strict quarantine measures and fairly long distances between affected localities.
The report, by Dr. Evgueny A. Nepoklonov, head of Russia's main veterinary department, said, "Practically all the infected localities are close to reedy lakes or marshes used by wild ducks. In these villages, the first birds to be affected are those kept in homes close to reservoirs." The prevalence of avian flu infection in wild ducks and geese is not known, but the virus is assumed to be "extremely widespread," he added.
Nepoklonov's report says nothing about the recent rumors of H5N1 in the Kalmykia area near the Caspian Sea in European Russia.
Another AFP report today said Russian authorities have told the European Union's executive commission there has been no avian flu outbreak near the Caspian Sea. The information came from an EU spokesman named Philip Tod.
WCS news release on Mongabay site
Mongolia's Aug 19 report to OIE
Aug 20 Russian report to OIE