19/02/2026
Anaplasmosis
This is a tick borne disease
Introduction
Anaplasmosis an acute (rapid onset and short but severe), fever producing disease of cattle, usually transmitted by Boophilus species Blue ticks and caused by a parasite which multiplies by binary fission in red blood cells, causing severe anaemia.
Severe Anaplasmosis is caused by Anaplasma marginale. This parasite occurs at the edge of the red cells. A mild, usually inapparent form is caused by Anaplasma centrale. This parasite occurs at the centre of the red blood cell.
The incubation period of the disease is about 3 — 4 weeks and is directly related to the infective dose. The disease occurs throughout the tropical and subtropical regions of the world.
Mode of spread
Anaplasmosis is not contagious. The source of infection is always the blood of an infected animal. Transmission does not take place by contact but generally via the medium such as the:
Blue tick: This is a one-host tick, spending its entire life on its host and for whose control once-weekly dipping or spraying is generally appropriate.
Biting flies can also transmit infecton.
Wild animals and other domestic animals can be infected and become reservoirs of infection
Infections in the sucking young usually does not happen. Once infected, animals remain carriers for life. In areas where cattle first become infected with Anaplasma marginale early in life, losses due to anaplasmosis are minimal. In animals less than 1 year old Anaplasmosis is usually subclinical, that is, there are no symptoms. in yearlings and 2-year-olds it is moderately severe, and in older cattle it is severe and often fatal.
Exposure of calves to infected ticks gives them an often life-long resistance. Paradoxically efficient tick control at this stage of their life will later expose cattle to possible life-threatening anaplasmosis. These facts must be kept in mind at all times.
Zebu cattle, with their relative resistance to heavy tick infestations, are less likely to be infected, but they are just as susceptible as European breeds. Carrier animals serve as reservoirs for further transmissions.
Serious losses can occur when mature cattle with no previous exposure are moved into areas where the disease is prevalent or when transmission rates are insufficient to ensure that all cattle are infected before reaching the more susceptible adult age. This latter situation can occur when a previously effective acaricide becomes ineffective, especially when it has previously been effective from calfhood into adulthood.
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