Anaplasmosis due to Anaplasma marginale, is a disease caused by a micro-organism that is a parasite of red blood cells. It affects domestic and wild ruminants, including cattle, sheep, goats and deer. However, in Canada it is primarily a disease of cattle.
In Canada, anaplasmosis due to Anaplasma marginale is an immediately notifiable disease under the Health of Animals Act. Laboratories are required to contact us regarding the suspicion or confirmation of this disease.
On this page
- Risk to human health
- Signs
- Where it is found
- Transmission and spread
- Diagnosis
- Treatment
- Disease prevention and control
Risk to human health
There is no human health risk associated with this disease. A human disease, human granulocytic ehrlichiosis (HGE) was renamed as human anaplasmosis in 2003, but this disease is caused by a different micro-organism.
Signs
Cattle of all ages can become infected, but the severity of disease is age-dependant.
- Illness is rare in animals under 6 months of age
- Illness is usually mild from 6 months to 1 year of age
- The disease is acute in 1 to 2 year-old animals, but is rarely fatal
- Mortalities range from 29% to 49% in animals older than 2 years that have experienced clinical disease
Clinical signs include:
- fever
- anaemia
- weakness; and
- respiratory distress
Affected dairy cattle will also have a rapid decline in milk production.
Where it is found
Anaplasmosis is common in tropical and sub-tropical regions of most of the world.
Anaplasmosis is not a regulated disease in the U.S. and is considered endemic there. Canada has experienced sporadic cases of anaplasmosis since 1968.
Transmission and spread
Anaplasmosis is transmitted through the red blood cells of infected animals. Once an animal is infected, it remains a source of the disease for life even after it has recovered.
Anaplasmosis is most often spread by ticks that bite infected cattle. The disease causing micro-organisms also infect and reproduce in the tick. The tick then transmits the micro-organism to other susceptible animals.
The disease can also be transmitted in infected red blood cells by biting flies or through contaminated instruments such as hypodermic syringes and dehorning equipment. Ticks capable of amplifying and transmitting anaplasmosis exist in Canada.
Diagnosis
Preliminary detection is based on clinical signs and a history consistent with exposure to risk factors such as ticks and infected imported animals. Producers wishing to perform laboratory testing for anaplasmosis should contact their private veterinarian.
Treatment
No drug for the treatment of anaplasmosis has been approved or licensed for use in Canada by the Veterinary Drugs Directorate of Health Canada. Long term use of antibiotics to control disease is not consistent with prudent principles of extra-label drug use and avoiding antimicrobial resistance. Widespread use of antibiotics could jeopardize international markets for Canadian animal products.
Disease prevention and control
Vaccines based on a live form of a related organism have been used in different parts of the world but there have been numerous reports of adverse effects.
At this time, no vaccine has been approved for use in Canada. In addition, it is not clear at this time if the live vaccine would protect against the strains that are found in North America.
Producers play a key role in protecting livestock from the threat of animal diseases. Producers are encouraged to discuss effective biosecurity measures with their veterinarian.