2007, Vol 1 No 2, Article 9
Spirochaetosis- A Devastating Tick Borne
M. A. H. Kanth
Almost all the vertebrate animals, except
the fishes somehow or the other are infested with ticks. The arthropods
cause significant losses to the Indian GDP. These losses are attributed
to the bites which cause among other things anemia, transmission of
diseases such as viral, bacterial, rickettsial and protozoan.
BIONOMICS OF ARGAS PERSICUS
Its shape is oval.
It is yellowish brown in color when unfed and slaty blue after
engorging on blood of host. In these sexes are separate and the two
sexes look almost identical.The
female lays eggs in the cracks and crevices of the poultry house and
under the bark of trees in batches of 100-250. Each female lays 4 to
7 batches of eggs in her lifetime. The eggs are small, spherical and
brown in color. The six legged larvae hatch from the eggs in 10-21
days. These feed on the host and often remain attached for up to six
days under their wings. They may also drop off and hide in the
crevices. After around seven days they molt and become nymphs. There
are two nymphal stages, each of which last for about two weeks. The
ticks engorge once in the nymphal stage and then the 2nd nymph molts
into the adult. The nymph and the adults hide in sheltered spots and
attach with the hosts during the night, feeding for about two hours
and causing restlessness and irritation to chickens.
This Argas persicus (soft tick) is responsible for the transmission of one important and serious disease, almost ranking second to Newcastle Disease (Ranikhet Disease) only, called spirochaetosis. The causative agent of spirochaetosis is the spirochaete bacterium Borrelia anserinum (Borrelia gallinarum), an actively motile filamentous organism usually about 8 to 20 microns (µ) long.
Following the bite
of the soft tick there is an incubation period of 5 to 9 days. Death
may take place after an acute illness lasting for 4 days or more.
Chronic cases may last for a fortnight. The mortality rate is very
high. Recovered birds may retain the infection
1. May be made by
blood examination during the acute stage.
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