Tick Fever – Gray Street Veterinary Clinic

TICK FEVER in CENTRAL HIGHLANDS DISTRICT


With the increasing number of properties recently found to have cattle ticks on cattle within the “Tick Free Zone”, you may find this short reveiw on tick fever benficial for your enterprise.

 

Various sizes of the engorged female Cattle tick 

Tick fever or Redwater, (also known as Babesiosis/Anaplasmosis) is typically

caused by a blood borne parasite transmitted by the cattle tick Boophilus microplus (pictured above) (Macleod 2009).   Babesiosis may be caused by infection by either Babesia bigemina or more commonly Babesia Bovis.  Anaplasmosis, caused by Anaplasma marginale, presents similarly to Babesios,

but is less common in this region.  Cases of tick fever may exhibit differently depending on causative organism and amount of infective dose.   Typically infection results in destruction of red blood cells (haemolysis), causing fever, lethargy, anaemia, red urine, jaundice and nervous signs (circling, head pressing, paralysis).

 

Tick fever typically occurs in areas of tick infested country of northern Australia, it may occur as an outbreak, infecting many animals or as a single case.  See map of Tick Zone (Macleod, 2009).  It is important to be aware that there is a difference between a heavy infestation of ticks and a case of tick fever, tick fever is transmitted by the tick but not every tick carries the parasite that causes tick fever.   

NB: Movement into the Tick Free Zone requires approval by a biosecurity officer at an designated inspection area.  In the central highland district this is carried out by DEEDI at EMERALD

 

MYTH: ‘ticky’ cattle (animals born and bred in the Tick Zone) are resistant to tick fever.  

FALSE:   All animals are susceptible to tick fever.

All animals that do not have an adequate immune response against the Babesia or Anaplasma organisms are susceptible to TICK FEVER (includes Bos indicus breeds, Bos taurus breeds, animals born in tick country, animals born in tick free zone.

 

Best immune response to Babesia and Anaplasma organisms develops between 3-9 months of age.   If animals do not develop an appropriate immune response when exposed to the blood parasites or they are not biten by a tick carrying the parasite at 3-9 months of age these animals may develop tick fever as an adult when exposed to the parasite, regardless of being born on the property in the tick zone.

 

Bos indicus animals tend to be more resistant to tick infestations and are also more resistant against the Babesia organisms than Bos taurus animals, however they are equally susceptible to Anaplasmosis (Tick fever caused by Anaplasma marginale) thus are still susceptible to tick fever.

 

 

Clinical signs and Diagnosis

History:  depressed, weak, loss of appetite reluctant to move, down/recumbent, found dead

Clinical signs: red urine, fever (temp > 40C), increased heart rate and respiratory rate,  jaundice, anaemia, poor condition, aggressive/ frenzied beha

            Antemortem findings: Microscopic examination of a blood smear to view organisms in blood cells.  (blood for smear must be taken from live animal from wither tip of the ear or tip of the tail). 

 

Animals may or may not show the clinical signs mentioned and many diseases in cattle exhibit fever and red urine, therefore the only hard and fast mean of diagnosis of Tick fever is with the mentioned blood smear further accurate diagnosis requires analysis of tissue samples taken from a deceased animal shortly after death. 

 

Treatment and Prevention

          After an accurate diagnosis by the pathologist and your local veterinarian treatment is carried out using, supportive care, therapeutics and an antiparasitic injection (“Imidox”) used in the immediate treatment and prevention of tick fever outbreak. 

          Vaccination is the best means of preventing an outbreak of Tick Fever in your herd, these can be ordered through your local veterinarian or through the TICK FEVER CENTRE in Wacol, Queensland.

          Efficacy of a vaccination program may also be improved with incorporating a tick treatment protocol as well to prevent heavy tick burden.

 


Vaccinated animals typically should not develop tick fever, however if you find that you are loosing animals through what is confirmed diagnosis of tick fever, ensure you are storing and using the product correctly as by your product guidelines.

 

The most commonly used vaccine is a chilled Trivalent vaccine (‘3-germ”) produced by the Tick Fever Centre in Wacol, Southern Queensland.   The vaccine protects against all three parasites, Babesia bovis, Babesia bigemina and Anaplasma marginale.

 

Vaccination Recommendations.

Following these guidelines will ensure that you are implementing the best practice on your property to achieve adequate protection against tick fever for your herd.

          Vaccinate all animals between the ages of 3-9 months – one shot is adequate

o       Calves to 2 months of age will receive natural immunity through colostrum/milk

o       Older can be vaccinated but must be cautiously monitored for vaccine reactions – which appear like a true case of tick fever and should be treated with antiparasitic treatment from your veterinarian if signs persist for prolonged period

o       Vaccine reactions can occur up to 8 weeks after vaccination

§         Long lasting Immunity against Babesia develops 3 weeks after vaccination whilst immunity against Anaplasma develops 8 weeks after vaccination – thus are susceptible to infection and vaccination reaction during this time.

          vaccinate animals intended for sale or movement in or near the tick zone

          vaccinate 10 weeks before sale

o       allows time for immunity to develop

o       Ensure that you have 2 weeks of a post recovery phase where animals can replace condition lost in the reaction period (may or may not happen)

          vaccinate animals with Bos taurus breeding, or have less than 50% Bos indicus

          vaccinate animals older than 9 months of age twice – boost animals 8 weeks after initial shot

o       ONE shot is 95% effective to protect animals for life, however there will be a small percentage of animals that do not develop an appropriate immune response to the 1st vaccination and thus may be susceptible to TICK FEVER later in life.

 

 

For more information contact us at Gray st Veterinary Clinic or check out the information supplied by Queensland Government Department of Primary Industries on Cattle Tick.

 

References:

Macleod, M (Queensland Government, Department of Primary Industries and Fisheries) 2009, Cattle Tick, 05 February, Department of Primary Industries and Fisheries, viewed 6 June 2011, .

Parkinson. TJ, Vermunt. JJ & Malmo J (2010) Disease of Cattle in Australasia, Vetlearn, Wellington.

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