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2007, Vol 1 No 2, Article 9

 

Spirochaetosis- A Devastating Tick Borne
Poultry Disease in Trans-Himalayas

M. A. H. Kanth
Department of Animal Husbandry

Srinagar, Kashmir
(Tel: +91-9906504239)

 


INTRODUCTION

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.
Spirochaetosis is one such disease in poultry caused by a soft tick called Argas persicus.
This tick is a serious pest of the chicken and it causes a great loss to the poultry farmer. It is particularly problematic for the poor poultry farmers of the trans Himalayan belt comprising the hilly areas of Jammu & Kashmir, Himachal Pradesh, Arunachal Pradesh, Assam, parts of Uttar Pradesh, and also areas in Nepal, Bhutan and Burma where the use of timber and mud is in vogue during poultry house construction. This soft tick thrives in the cracks and crevices of these poultry houses and remains a constant irritant to the farmer.

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.
These ticks are very tenacious and can live for 3 to 5 years without feeding.
 

DISEASE TRANSMISSION

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 () long.

CLINICAL SYMPTOMS

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
Pyrexia, weakness, drowsiness, ruffling of feathers, anorexia, anaemia, diarrhea, intense thirst drop in egg production, the affected birds assume a crouching posture with the head hanging down and eyes closed, emaciation and finally paralysis spreading from the extremities.
The disease has been found in chicken, turkeys, geese, ducks etc.

DIAGNOSIS

1. May be made by blood examination during the acute stage.
2. In acute cases spleen may be 4 or 5 times its normal size.
3. The liver is enlarged, fatty and sometimes shows necrotic foci.
4. The blood does not coagulate.

TREATMENT

(A) Curative


(i) Several arsenical preparations such as Soamin, Salvarsan, Atoxyl, Sulopharsenol etc. Sulpharsenol is injected by the intramuscular or intravenous route at a dose of 2 to 4 grams dissolved in 2 to 4ml of distilled water. Recovery is usually obtained after one injection. 


(ii) Single dose of Penicillin usually affects a complete cure. 15000 I.U. of Penicillin subcutaneously is very effective. 


(B) Prophylactic


(i) Spirochaetosis freeze dried vaccine @ 1ml intramuscularly renders immunity for up to 18 months 


(ii) Tick Control: The following measures are indicated:
(a) Practical Measures
-Housing should be tick proof, without cracks and crevices. Important factor is to minimize the use of unprocessed timber. Also fumigation of the house be taken up at least twice a year.
-Quarantining of fresh arrivals till one is satisfied of their being tick free.
-Burning of weeds in farm premises.
-Rodents serve as mobile museums for the various stages of ticks. Rodent control will minimize chances of onward transmission to birds.
-For treatment of infected premises the birds must be removed from their run and houses to be placed in wooden crates in which the attached larvae will drop off within 10 days from their bodies. Meanwhile the houses will be cleaned an fumigated efficiently. The waste material is best burned, while the wooden crates could be sprayed clean. Various acaricides are available to this end.
(b) Research Trends:
Use of repellents (dimethyl phthalate, diethyl tohimide etc.)
Use of hormones.
Irradiation techniques.
Biological control.
Male sterile techniques.
Genetic control.
Host resistance.


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