Mary Allen
Ticks transmit various infectious diseases. We present two of them in more detail here so that you can educate dog owners in the best possible way.
Babesiosis and hepatozoonosis are parasitic infectious diseases, but they are not transmitted by mosquitoes but by ticks. Both are caused by protozoa (single-cell organisms) and, like leishmaniasis and filariasis, belong to the so-called “travel or Mediterranean diseases”. However, babesiosis and presumably also hepatozoonosis is already endemic in Germany (occurring in certain areas). Other diseases transmitted by ticks are Ehrlichiosis, Anaplasmosis, Rickettsiosis, and Lyme disease.
Babesiosis
Canine babesiosis is a parasitic infectious disease with various forms and a potentially fatal outcome. Other names are piroplasmosis and “canine malaria”. It is not one of the zoonoses.
Pathogen and Spread
Babesiosis is caused by unicellular parasites (protozoa) of the Babesia genus. They are transmitted by various types of ticks (above all the alluvial forest tick and the brown dog tick) and only attack the erythrocytes (red blood cells) of the mammalian host, which is why they are also called haemoprotozoa. They are highly host-specific to both their tick vector and their mammalian host. In Europe, Babesia canis (Hungarian and French strains) and Babesia vogeli play the most important role, with Babesia canis usually leading to serious diseases (especially the Hungarian strain), while Babesia vogeli infection is usually mild.
infection
Female ticks are primarily responsible for the transmission of Babesia, the role of male ticks in the infection has not yet been clarified. Ticks serve both as a vector and as a reservoir. The Babesia are ingested by the tick during sucking. They penetrate the intestinal epithelium and migrate to various organs such as the ovaries and salivary glands of the tick, where they multiply. Due to the possible transovarial transmission to the offspring, larval stages of ticks can also be infected with the pathogen.
Female ticks have to suckle on the host for at least 24 hours before the infectious stages of the pathogen (so-called sporozoites ) in the tick’s saliva are available for transmission to the dog. Babesia transmission usually occurs 48 to 72 hours after the tick bite. They only attack the erythrocytes, where they differentiate and divide into so-called merozoites. This causes cell death. The incubation period is five days to four weeks, the prepotency one week. If an animal survives the disease without treatment, it develops lifelong immunity but can shed the pathogen for life.
Transmission is still possible as part of biting incidents and blood transfusions. Vertical transmission from bitches to their puppies has also been demonstrated for a Babesia species.
symptoms
Babesiosis can take different forms.
Acute or peracute (most common with Babesia canis infection ): The animal is presented as an emergency and shows:
- high fever (up to 42 °C)
- Highly disturbed general condition (lack of appetite, weakness, apathy)
- Tendency to bleed the skin and mucous membranes with anemia, reticulocytosis, and excretion of bilirubin and hemoglobin in the urine (brown coloration!)
- Yellowing of the mucous membranes and sclera (icterus)
- Thrombocytopenia disseminated intravascular coagulation
- shortness of breath
- Inflammation of the mucous membranes (nasal discharge, stomatitis, gastritis, hemorrhagic enteritis)
- Muscle inflammation (myositis) with movement disorders
- Enlargement of the spleen and liver with abdominal dropsy (ascites) and edema formation
- epileptiform seizures
- acute renal failure
If left untreated, the acute form almost always leads to death within a few days.
Chronic :
- changing rise in body temperature
- anemia
- emaciation
- apathy
- weakness
Subclinical :
- light fever
- anemia
- intermittent apathy
Diagnosis
The type of diagnosis depends on the course of the disease.
Acute illness or infection less than two weeks ago: direct detection of the pathogen by:
- Microscopic blood tests for Babesia-infested erythrocytes: Thin blood smears (Giemsa stain or Diff-Quick) from peripheral capillary blood (auricle or tail tip) are best suited, as this usually contains a higher number of pathogen-infected cells.
- Alternatively (especially if the result of the blood smear is inconclusive) from the fifth day after infection, PCR from EDTA blood with the possibility of differentiating the pathogen, which can be important for therapy and prognosis.
Chronic illness or infection more than two weeks ago :
Serological test for antibodies against Babesia (IFAT, ELISA), except in the case of a vaccinated animal.
- Babesia canis (France strain): often low antibody production
- Babesia canis (Hungary strain): often the high formation of antibodies
- Babesia vogeli: often low antibody production
The following diseases in particular should be considered in the differential diagnosis :
- Immunohemolytic anemia (toxic, drug-related, or autoimmune)
- systemic lupus erythematosus
- anaplasmosis
- Ehrlichiosis
- mycoplasmosis
therapy
Therapy aims to eliminate the pathogen, even if this reduces the duration of immunity to one to two years. If an acute illness is transferred to a chronic phase without clinical symptoms, there is lifelong immunity and the animal usually no longer becomes ill but acts as a carrier. This must be viewed very critically, especially about the Hungarian strain of Babesia canis, since the alluvial forest tick lays 3,000 to 5,000 eggs after a blood meal, of which about 10% are infected with Babesia through transovarial transmission, and at the same time mortality in one New infection with this Babesia strain is up to 80%.
Hepatozoonosis
Hepatozoonosis is also a parasitic infectious disease in dogs. The name is misleading because the disease is not a zoonosis and therefore does not pose a danger to humans.
Pathogen and Spread
The causative agent of hepatozoonosis is Hepatozoon canis, a unicellular parasite from the coccidia group. It therefore also belongs to the protozoa. Hepatozoon canis originally comes from Africa and was introduced to southern Europe from there. In the Mediterranean region, up to 50% of all free-living dogs are considered infected. But not only the dog is a mammalian host for the pathogen, but foxes and cats are also carriers. So far, hepatozoonosis has been counted among the classic travel diseases. In 2008, however, it was found in two dogs in the Taunus that had never left Germany. In addition, as part of a study on foxes in Thuringia, a high percentage of the fox population became seropositive for Hepatozoon contested. The brown dog tick is the main carrier. The hedgehog tick is also assigned a role in transmission (especially in foxes), but the exact transmission route is still unknown here.
infection
As a carrier of Hepatozoon canis, the brown dog tick can survive all year round in apartments, heated kennels, etc. It actively moves toward its host and goes through the entire development cycle of egg-larva-nymph-adult tick in just three months.
Infection with Hepatozoon canis does not occur through the bite but through oral ingestion (swallowing or biting) of a tick. The pathogens migrate through the intestinal wall of the dog and first infect the monocytes, neutrophilic granulocytes, and lymphocytes, then the liver, spleen, lungs, muscles, and bone marrow. The development, which lasts about 80 days, includes several stages both in the tick and in the dog and ends with the formation of so-called intraleucocytic gamonts. These are in turn ingested by the tick during the act of sucking. Reproduction and development are subject to seasonal fluctuations. In contrast to babesiosis, the transovarial transmission of the pathogen in the tick could not be demonstrated. The length of the incubation period is not known.
symptoms
In the vast majority of cases, the infection is subclinical or symptom-free, but in individual cases, it can also be accompanied by serious symptoms, especially in mixed infections, e.g. B. with Leishmania, Babesia, or Ehrlichia.
Acute :
- Fever
- Disturbed general condition (lack of appetite, weakness, apathy)
- lymph node swelling
- weight loss
- eye and nasal discharge
- Diarrhea
- anemia
Chronic :
- anemia
- thrombocytopenia
- emaciation
- Muscle inflammation with movement disorders (stiff gait)
- Central nervous phenomena with epilepsy-like seizures
The massive formation of γ -globulins and large immune complexes can lead to liver and kidney failure.
Diagnosis
The detection of the pathogen occurs directly or indirectly in acute and chronic cases of illness.
Direct pathogen detection :
Blood smear (Giemsa stain, buffy coat smear): Detection of the gamonts as capsule-shaped bodies in the white blood cells
PCR from EDTA blood
Indirect pathogen detection: determination of the antibody titer (IFAT)
In the differential diagnosis, anaplasmosis, Ehrlichiosis, and immunopathy in particular must be taken into account.
therapy
There is currently no safe therapy to eliminate the pathogen. Treatment primarily serves to alleviate the course of the disease.
prophylaxis
There is currently no reliable chemo- or vaccination prophylaxis. Dog owners should be given tips on tick repellents. However, successful prevention is difficult due to the ingestion of the pathogen by swallowing or biting the tick. Dogs that come into direct contact with the game while hunting or that pick up dead (wild) animals with ticks are to be regarded as particularly at risk.
Prevention by protection against ticks
Two approaches are used to ward off ticks:
- Defense against ticks (repellent effect) so that they do not attach to the host
- Killing the ticks (acaricidal effect) before or after attachment to the host
This can be done in different ways:
- spot-on preparations
- spray
- collars
- chewable tablets
- spot-on preparations
These are applied directly to the skin on the dog’s neck if the coat is parted, and also in the caudal area of the back in large dogs. The animal should not be able to lick off the active substance. This spreads from the points mentioned over the entire body. The dog should not be petted in these areas for the first eight hours (therefore recommended use in the evening before going to bed) and if possible not get wet in the first two days (bathing, swimming, rain). The duration of action is i. d.R. three to four weeks.
The active substance contained is either permethrin, a permethrin derivative, or fipronil. Permethrin and its derivatives have an acaricidal and repellent effect, fipronil only acaricidal. Important: Permethrin and pyrethroids are highly toxic to cats, so under no circumstances should these preparations be used on cats. If dogs and cats live in the same household, care should be taken to ensure that the cat does not have contact with a dog treated with permethrin/pyrethroid until the active substance has been completely absorbed. Permethrin and fipronil are also toxic to aquatic animals and invertebrates.
spray
Sprays are sprayed all over the body and have a similar effect to spot-on preparations, but are more complicated to use. For households with children or cats and depending on the active ingredient, they are rather unsuitable. They are therefore not taken into account in the table below.
collars
Collars must be worn by the dog at all times. They release their active ingredient into the dog’s fur for up to a few months. Intensive human contact with the collar should be avoided. A disadvantage is that the dog with the tick collar can get caught in the bushes. Therefore, hunting dogs should better not wear such a collar. The collar must be removed when bathing and swimming, and the dog should not be allowed into the water for at least five days after putting it on for the first time.
chewable tablets
Tablets allow direct contact with the animal, as well as bathing and swimming immediately after use. The administration is usually unproblematic. However, the tick first has to attach itself to the host and absorb the active substance during a blood meal to be killed after about twelve hours. There is therefore no repellent effect.
An overview of spot-on preparations, chewable tablets, and collars currently on the market can be found below in a downloadable table.
Tick repellents should be used throughout the tick season or the year in areas with an increased risk of tick-borne diseases. In principle, it should only be used in healthy animals. Some preparations are also suitable for use in pregnant and lactating bitches and puppies. If you have skin diseases or skin injuries, you should avoid using a spot-on preparation.
In addition, after every walk, a thorough coat check and immediate complete removal of all ticks found is important. This can be done with a tick tweezer, card, or similar tool.
In individual cases, dog owners report positive experiences with the external or internal use of coconut oil, black cumin oil, cistus (Cistus incanus), brewer’s yeast, garlic, or spraying with mixtures of essential oils. However, a proven effect cannot be attributed to these measures, just as little as amber necklaces or energetically informed collar pendants. Additionally, some essential oils are irritating and garlic is potentially toxic.
Behavioral prophylaxis
Known tick biotopes should be avoided as much as possible. Dogs should not be taken on trips to risk areas during risk periods.
Frequently Asked Question
How old do dogs with hepatozoonosis get?
Life expectancy in hepatozoonosis
That depends on the immune competence of the infected dog, the age, the comorbidities, and how quickly the therapy is started. If the disease is recognized quickly and treatment is started immediately, the chances of recovery are good.
How is babesiosis transmitted?
transmission of babesiosis
Babesiosis is caused by protozoa transmitted by tick bites. The tick must suckle for at least twelve hours for the infection to be successful.
Is babesiosis contagious from dog to dog?
Very rarely, it can also be transmitted from dog to dog through a bite or in the womb of the puppy. Another source of infection would be a blood transfusion with contaminated blood. Good to know: The pathogens that cause babesiosis in dogs cannot be transmitted to humans.
Can babesiosis be transmitted to humans?
Babesiosis is a so-called zoonosis – an animal disease that can be transmitted to humans. Ticks that act as intermediate hosts can transmit babesiosis to humans. The disease is very rare in Germany.
Is hepatozonosis contagious?
Four-legged friends cannot infect humans or other animals directly with hepatozoonosis.
What happens when a dog eats a tick?
When dogs eat a tick, it can, in rare cases, transmit Lyme disease, hepatozoonosis, and anaplasmosis. Infection with babesiosis, Ehrlichiosis, and tick-borne encephalitis are also possible. The good news? Eating a tick is significantly less dangerous than a tick bite.
How long does it take for ticks to transmit diseases to dogs?
Only ticks can transmit Borrelia to the dog, an infection with another dog is almost impossible. At the earliest after 16 hours, in most cases only after 24 hours, the Borrelia is passed on from the tick to the dog.
How does Lyme disease affect dogs?
A dog suffering from Lyme disease may show the following symptoms: Slight fever and lethargy. lymph node swelling. Joint swelling and lameness due to joint inflammation (arthropathies).