Scott McPherson's Web Presence

Oh, the things we learn when researching avian influenza.

Apparently, a brisk cottage industry in Indonesia -- and duplicated across Asia -- is the raising of a certain species of swallow called the "Edible-nest swiftlet."  Rather than be redundant, let me point to the definition, straight from the Website 10000birds.com, found at:  http://10000birds.com/edible-nest-swiftlets.htm

The Edible-nest Swiftlet Collocalia fuciphaga is found throughout S E Asia and is renowned for the fact that the birds’ nests are used for making bird’s nest soup. During the breeding season, the salivary glands of this species expand to produce the special saliva for binding detritus together for building the nest, which is a shallow cup stuck to the cave wall. Nests which are ‘white’ and made purely or almost purely of saliva - like those of the Edible-nest Swiftlets above - are the most valued. When cooked, the birds’ nests have a gelatinous texture and in Chinese cuisine high medicinal and aphrodisiac qualities are ascribed to these nests. Scientific investigations reveal these nests to be high in protein with about 7% lime. Many consumers of bird nest soup report significant improvement in appetite. However, some others noticed excessive secretion of gastric acid that may cause acid reflux symptoms.

Nests are harvested from cave walls and there is increasing concern that over-harvesting is causing several species of cave swiftlets to become scarce. Bird nest merchants in southeast Asia (including Vietnam, Indonesia, Thailand) have started to raise and breed the swiftlets in house-like structures. They build the shelters to attract wild swiftlets to build nests in them. The “wrong” kind of nests are then destroyed along with the eggs inside. Over time, the selection process only leaves behind a colony of swiftlets that produce the right kind of nest for the trade. “House nests” are priced much lower than the “cave nests” due to the level of risks involved in the harvesting process of the latter. (Adapted from Birding India: Edible-nest Swiftlet) (bold mine)

Apparently, another item left behind is H5N1, or so the locals fear.  Now, both the WHO and Pro-Med are reporting that the focus of the investigation is the presence of a swiftlet in the immediate vicinity of the dead 31-year old healthcare worker.  I quote directly from the WHO release on the case:

The Ministry of Health of Indonesia has announced a new case of human infection of H5N1 avian influenza. A 31-year-old male from the Bengkalis District, Riau Province developed symptoms on 31 October, was hospitalized on 3 November and died in an AI referral hospital on 6 November. Identification of the source of his infection is ongoing and includes investigation into a large swallow farm in close proximity to the case's house. (bold mine)

The villagers have raised these swiftlets to harvest their precious nests from the rooftops of buildings.  There is video of the Riau locals smoking out remaining swiftlets and burning the leftover nests from Indonesian television station Liputan6.com, specifically at: http://www.liputan6.com/news/?d=150643&c_id=7 .  The video is the last news story on the loop.

Fascinating possible vector, eh?  This adds to the (growing) list of potential H5N1 vectors, including housecats, pigs and dogs in Southeast Asia.  China has also been concerned about a possible link between swallows and H5N1.  The following is from the Chairman of Health Promotion and Detection of the Chinese University of Hong Kong, from February 4, 2006.  http://www.cuhk.edu.hk/health_promote_protect/announcement-06feb.html , and the context is within various influenza warnings.

The University Library has for years been a favorite nesting area by swallows.  As a precaution to prevent passersby from walking underneath the swallow nests outside the Library, the Estates Management Office has placed nice pot plants to block a section of the pedestrian walkway near the carpark entrance of Tin Ka Ping Building leading up to the central steps.  “No Parking” signs are also posted to inform drivers not to park their cars in that area.  Pot plants are also placed around areas beneath the swallow nests outside Sir Run Run Shaw Hall.

How could swallows handle the stress of H5N1 without a mass die-off?  A partial answer might be found in a recent report entitled "Ecologic Immunity of Avian Influenza (H5N1) in Migratory Birds."  An excerpt follows:

Far less information is available, however, on 1 important aspect: how do infected birds perform during long-distance migration? Møller et al. (22) showed that barn swallows (Hirundo rustica) with large energy reserves maintain better immune function during migration, clear ectoparasites and blood parasites more effectively, and arrive earlier at breeding grounds (which is an important determinant of reproductive success) than birds with poor energy reserves.

Swallows are a secondary vector of the Buggy Creek Virus, related to equine encephalitis, and found in areas of the Midwest, including Oklahoma and Nebraska.  From a 2004 news release from the the University of Tulsa:

Charles R. Brown, a biology professor at The University of Tulsa, has received a grant of $856,000 from the National Institutes of Health to study a virus that infects cliff swallows. The research may help understand the transmission of other viruses that affect humans, such as West Nile virus.

Brown will be specifically studying the Buggy Creek virus, named after the location where it was first discovered in western Oklahoma. The virus is known to live in the cliff swallow and is transmitted from bird to bird by the blood-sucking cimicid insect. It is not known if the virus affects the health of birds or humans, or if mosquitoes spread the virus to humans.

The Buggy Creek virus is similar to the one that causes Western equine encephalitis, a disease that is spread to horses and humans by infected mosquitoes, but which generally causes only flu-like symptoms in humans.

When the swallows migrate to South America in the winter, the parasitic bugs burrow beneath the mud nests, re-emerging when the birds return in the spring, shortly before the breeding season in May and June. (bold mine)

I bolded the South America part because of the article that appeared last year, warning that we might be looking in the wrong hemisphere for H5N1.  Migratory patterns in the Northern Hemisphere are very well-known, but such patterns in the Southern Hemisphere are not well-plotted at all, especially those in South America (home to malaria, dengue, and other dangerous diseases), according to the University of Florida.

So these swiftlets are about to go through some incredible scrutiny.  Let me give a huge tip of the hat to Dr. Henry Niman and FluTrackers poster Dutchy for bringing this to light.