Ticks found to kill animals since 1894!

The Australian Government’s Department of Agriculture and Water Resources Website article “A Veterinary Awakening: The History of Government Veterinarians in Australia” discusses how English bacteriologist Charles Joseph Pound, a former Pasteur Institute student, was lauded for saving the cattle industry in Australia for his work on tick fever.  Pound investigated the ‘redwater’ disease among cattle in Australia’s north in 1894.  Yes way back in 1894!

He quickly realised that redwater disease was carried by ticks.

When the disease first appeared in Queensland, up to 90 per cent of cattle in some areas died and it was estimated that some £3 million worth of cattle were lost during the first six years of the disease. 

Pound worked with an American by the name of JS Hunt, an expert on tick fever, to carry out inoculation trials in Australia. Once a method for producing tick fever vaccine from the blood of infected cattle was developed Pound went on to save hundreds of thousands of cattle from tick fever and the tick fever research station established in Wacol, Queensland, in 1966 is named after Pound in honour of his achievements.

Redwater disease is also known as Bovine Babesiosis.  The symptoms in animals are:

bovis

  • High fever
  • Parasitaemia (percentage of infected erythrocytes) - maximum parasitaemia is often less than one per cent
  • Neurologic signs such as incoordination, teeth grinding and mania
  • Some cattle may be found on the ground with the involuntary movements of the legs. When the nervous symptoms of cerebral babesiosis develop, the outcome is almost always fatal.
  • Dark coloured urine
  • Anorexia

bigemina

  • Fever
  • Anorexia
  • Animals likely to separate from herd, be weak, depressed and reluctant to move
  • Haemoglobinuria and anaemia
  • Dark coloured urine
  • Central nervous system (CNS) signs are uncommon
  • Lesions

The treatment recommendations are that mild cases may recover without treatment and sick animals can be treated with an antiparasitic drug. Treatment is most likely to be successful if the disease is diagnosed early; it may fail if the animal has been weakened by anaemia.  Sounds a lot like human Lyme disease doesn’t it?

Disturbingly, there are concerns that the product recommended “Imidocarb”, which has been reported to protect animals from the disease, produces residues in milk and meat a cause for concern to humans.

“In some cases, blood transfusions and other supportive therapy are a consideration.  Babesiosis vaccines are readily available and are highly effective. Anti-tick vaccines are also available in some countries and can be used as part of an integrated program for the control of ticks.

Babesiosis can be eradicated by eliminating the host tick(s). In the US, this was accomplished by treating all cattle every two to three weeks with acaricides. In countries where eradication is not feasible, tick control can reduce the incidence of disease.

Babesiosis resembles other conditions that cause fever, and hemolytic anemia. The differential diagnosis includes anaplasmosis, trypanosomiasis, theileriosis, bacillary hemoglobinuria, leptospirosis, eperythrozoonosis, rapeseed poisoning and chronic copper poisoning. Rabies and other encephalitides may also be considerations in cattle with central nervous system signs”.

Type “tick’ into the search engine of the Department's Website and you will find numerous articles on ticks, Emergency Animal Disease Bulletin – No 119, being one which took my interest.  The article reads:

“Nairobi sheep disease (NSD) is a highly pathogenic disease of sheep and goats, causing acute haemorrhagic gastroenteritis in naïve animals. NSD has a limited effect on animals bred in endemic areas but large losses can occur when naïve animals are exposed to the virus. Originally limited to East Africa, NSD now occurs in most of Africa as well as Sri Lanka and India. More recently, a novel strain of NSD virus was sequenced from ticks in China.

NSD is listed as a notifiable disease by the World Organisation for Animal Health (OIE) and is on the Australian national list of notifiable animal diseases. Australia is free of NSD virus and has never had a reported case”.

The article discusses Haemaphysalis longicornis  tick which was found in China in 2013. This Chinese isolate is genetically divergent from both NSD virus in Africa and Ganjam virus in Asia. And “The increased use of modern molecular techniques has shown that the virus has a much wider distribution than previously suspected”.

You can read the blog here about the longhorned tick and how it has made its way into the USA recently and leaves me skeptical of our Governments screening abilities, especially when they go on to say in the above article that “the longhorned tick is present in Australia”.  Why is it that the Australian Government does not seem to be concerned about the effects on humans but America is?

The Department of Agriculture and Water Resources states:

“Changes in land use such as agricultural encroachment, wetland modifications and expansion of urban environments have all increased exposure of humans and animals to ticks”.

It appears that a mass outbreak of vector borne diseases in humans is alive and well in Australia, however, the concern for our animals is more important than we mere mortals. Confirmed by the following comment:

“If an outbreak of NSD occurred in Australia, the economic impact would be significant due to high mortality in sheep and goats, trade and production losses, and the cost of control and eradication.”

Now that human Borreliosis is listed by the World Health Organisation ICD11, perhaps we humans may be the subject of such concern by the Australian Government.  In the meantime, there appears to be a disconnect between the Australian Government's Department of Health and the Department of Agriculture and Water Resources.


Article by Anne Ryan.  Opinions in this article are mine and do not reflect the opinions of the LDAA.