'Gallsickness' Anaplasmosis
By Dr Mackie Hobson BSc(Agric),BVSc

1. Diseases

Anaplasmosis, formerly known as ‘gall sickness’, in Angora goats is not of great importance as it is usually a subclinical or mild condition that rarely results in a fever, anaemia, icterus or death. It does however have more of an effect on goats than sheep.

Cases of anaplasmosis would occur in the Karoo if conditions favoured the vectors - arthropods (ticks, mosquitoes, biting flies).

In sheep and goats ‘gall sickness’ it is caused by the blood parasite Anaplasma ovis an erythrocytic rickettsial organism. Anaplasma can also affect cattle, sheep, buffalo, and some wild ruminants.

Distribution of ‘gallsickness’- depending on season (map dept Agriculture)

How is anaplasma ovis transmitted?

Rhipicephalus (Boophilus), the blue tick is the major vector however 17 species of ticks are suspected carriers of the disease. Blood sucking insects such as mosquitoes and biting flies as well as needles are also capable of transmitting the disease.

Clinical signs:

Usually the cases would be subclinical or mild, however clinical signs are more common in goats than sheep. Historically farmers in determining which animals were infected would treat those that lagged behind the flock when herded.

• Fever, not always present
• Anaemia with signs of fatigue and respiratory effort.
• Loss of condition
• Appetite remains unaffected
• Icterus is not always a sign even in cases where deaths occur
• Abortions are possible

Post Mortem findings:

• Pale, may be icteric
• Emaciation
• Straw coloured fluid in body cavities
• Lungs pale and oedematous
• Liver large and yellow-brown, large gall bladder

Diagnosis:

Presence of the parasite on a blood smear but it possible the parasite levels may already have declined when clinical signs are present.

Antibody titres can also confirm exposure.

Photo: Wikipedia / Anaplasmosis visible in the red blood cells (arrow)

Treatment;

The tetracyclines are effective and for practical reasons the  Long Acting (LA) formulations are used at 20mg/kg.

Treat parasites (internal and external) as these may precipitate the disease.

Reference:

Infectious diseases of livestock. J. Coetzer, G. Thompson, R.Tustin