Common parasites can cause serious problems.

Ectoparasites, such as ticks, are more harmful to animals and humans than is generally realised. Not only do they cause debilitating and irritating conditions themselves, but they can transmit hazardous diseases to their hosts and humans. Certain zoonoses (diseases transmitted from animals to humans) have increased in recent times due to the rise of the pet population, with ticks and fleas being the main causative species. 

Biliary Fever (Babesia) In Dogs

Biliary is a serious tick-borne disease which affects the red blood cells of dogs, cats, horses and livestock. Ticks transmit tiny infectious parasites into their host’s bloodstream where they multiply in the red blood cells. During this continuous multiplication process many more blood cells are invaded and eventually destroyed, resulting in anaemia. This disease can be most troublesome as the clinical signs may be acute, chronic, or relapsing.

Clinical Signs of Infection

• Anaemia (pale mucous membranes)
• Anorexia and depression.
• Vomiting.
• Dehydration.
• Jaundice (yellow mucous membranes)
• Red urine.
• Nervous symptoms.

The ticks that prey on your pet are mainly the yellow dog tick (Haemophysalis elliptica) and the kennel tick (Rhipicephalus sangeuineus). Both are major transmitters of canine biliary fever (Babesia canis). In severe infections death may occur very quickly, within as little as one day, unless there is an effective response to treatment. Some animals in endemic areas will carry the disease, but without clinical signs, whilst in other animals showing poor condition, the disease may have reached a chronic stage.

Ticks attaching to such infected carrier dogs, will engorge blood cells containing Babesia parasites. In the tick’s digestive system these parasites undergo another developmental cycle, and by further multiplications disseminate throughout the the tick’s intestinal cells.  More importantly, these parasites also invade the various organs of the tick, including the ovaries of the female and subsequent eggs laid by the female. This transmission ensures the propagation of the Babesia organisms into the next tick generation. This means that a certain percentage of the larval stages of a Babesia-infected tick pass the infection to dogs without prior to attachment to infected of carrier animals.

Humans in close and frequent contact with infected animals are at risk of contracting tick-borne diseases, of which tick-bite fever (infection with Rickettsia conori) is the most common in South Africa. Tick-borne diseases are transmitted by the kennel tick as well as other tick species. Of late, Congo haemhorraghic fever, which is transmitted by the immature bont tick (Hyalomma spp), also has to be considered as an increasing health hazard.

Diagnosis and Sampling

Blood samples, preferably from a capillary bed such as the ear tip, should be collected by a veterinarian for parasite identification as the ear tips are richest in parasites.

Ehrlichiosis

Ehrlichiosos is a tick-borne rickettsial disease transmitted through the saliva of ticks. This bacterium infects and kill the while blood sells. Clinical signs may be acute or chronic.

Clinical signs of Ehrlichiosis infection:

• Lethargy
• Anorexia and weight loss
• Fever
• Bleeding Tendencied (example through the nose)
• Anaemia
• Enlarged Lymph Nodes
• Ocular Pain

Treatment

Treatment of biliary involves a visit to your local veterinarin, where he/she will recommend the best treatment for the animal according to clinic signs, often with a combination of products. He may also suggest post-biliary supportive treatment that can be given at home.

Prevention

• Babesiosis is normally transmitted by tick bites, so prevention depends on stopping the attachment and feeding of ticks, which may be achieved by avoiding tick-infested areas and by using spot-on products, dips or repellents with or without acaricides.
• Each treatment regime has its place in the control of ticks. Some are fast-acting but short-lived (Capstar) while others are long-acting (Frontline, Advantix). Some combat on-host parasites while others are off-host.
• Depending on the severity and stage of the tick challenge, different products are recommended. Some products work only against ticks, while others have a combined efficacy to treat both ticks and fleas. A product that repels ticks reduces the transmission of biliary fever.
• Babesiosis infection in a dog does not usually pose a direct risk for another dog as blood transfer of ticks are needed for transmission of infection.

References : Bayer HealthCare, Dr R Lobetti: Vetmed 2001, M Fisher, J McGarry: Focus on small animal parasitology.