Avioserpens Wehr & Chitwood, 1934
Type species of the genus: Avioserpens
galliardi Chabaud & Campana, 1949
Distribution:
At
least three species of Avioserpens have caused epizootics in domestic
birds in Eurasia. Species of Avioserpens are reported from Asia, Europe
and North America. (Kinsella, 2008)
Food Sources and Feeding strategies for the genus Avioserpens
Parasitic in the subcutaneous tissues of
waterbirds.
The life cycles of Avioserpens
spp. resemble those of
other dracunculoids in the requirement of a copepod intermediate host and
in its initial development in the connective tissues of the
definitive host.
In Avioserpens taiwana, for example, femeles occur in
tumor-like swellings in subcutaneous tissues of the definitive
waterbird host, mainly in the sub-mandibular areas. The anterior
ends of gravid females nematodes pierce the swelling to produce an
opening through which the first-stage larvae escape into the water.
They are ingested by copepods, in which they penetrate through
the gut wall into the hemocoel. They molt to the 2nd stage after 3-4
days at 28-30 C and to the third stage in 7 days. Adult males
can be found in the mesenteries 18 days postinfection and females in
the subcutaneous tissue at 20 days.
The life cycles of A. mosgovoyi and other species are
quite similar.
Paratenic or transfer hosts include fish (roach, gobies,
and sticklebacks), frogs, and dragonfly larvae. Paratenic hosts can
ingest infective copepods and the infective, encysted larvae will
persist in their tissues for up to 2.5 months. Thus, definitive
hosts can become infected by ingestion of either infected copepods
or infected paratenic hosts.
After ingestion by the definitive host, the third molt takes
place in the body cavity, and the fourth-stage larvae migrate via
the air sacs to the subcutaneous tissues, where
they molt to adults12-14 postinfection. Adult females start to
produce larvae at 4 weeks postinfection. Males persist in tissues
much longer than do females, up to 260 days.(Kinsella, 2008).
Avioserpens spp. produce tumorlike swellings in
the submandibular region and legs, and sometimes on the shoulders and shanks of
ducks and other waterbirds. The infections are sometimes termwed
Avioserpensosis.
Swellings resulting from the infections can
intefere with swallowing, result in asphyxiation, and death. Swellings
may be reabsorbed by the body of the host or they may become very large,
even as large as the head of the bird. In early stages of the infection,
the swelling is painless and soft, but as the infection progresses, it
becomes hard, voluminous, and painful.
At least three species of Avioserpens
have caused epizootics in domestic birds in Eurasia, but similar
outbreaks have not been reported in wild birds..
Some cures in China have been achieved by direct injection of
anthelmintics into the parasitic swellings, although this is not common
practice in western veterinary medicine (Chen et al. 1984).
Prevention of infections in ducklings can be achieved by providing
uncontaminated food and water and preventing contact with paratenic
hosts (Kinsella, 2008)
Chen, F., C. Y. Xue, X. L. Zhou, K. R. Zhang,
and G. Z. Ying. 1984. The finding of Avioserpens sichuanensis in ducks
in Huangyan County, Zhejiang Province, China (in Chinese). Chinese
Journal of Veterinary Medicine, Zhongguo Shouyi Zazhi 10:23-25
Kinsella, J.M. 2008. Avioserpenosis. .Chapter 22
in Atkinson, C.T., Thomas, N.J., Hunter, D.B. Parasitic Diseases of Wild
Birds. Wiley-Blackwell
Wehr, E. E., and B. G. Chitwood. 1934. A new
nematode from birds. Proceedings of the Helminthological Society of
Washington 1:10-11.
Revised by Howard Ferris:
October 15, 2026.