Ticks & Co – small monsters, big danger

Every year the first sunny days of spring attract people and animals outside. Finally, the walk with the dog or the ride on horseback becomes a pleasure again. But watch out: With the rising temperatures, there is also an insidious danger lurking in the undergrowth – ticks. Along with mosquitoes and flies, they are among the animal species responsible for vector-borne diseases.

Therefore, contact your veterinarian in good time to take the right prophylactic measures so that you can enjoy nature with your four-legged friend without worrying and well protected!

Vector-borne diseases are diseases caused by bacteria, parasites and viruses. These, in turn, are transmitted – in humans and animals – by blood-sucking vectors (carriers) such as ticks, mosquitoes, fly species, etc. Ticks transmit the diseases borreliosis, babesiosis, early summer meningoencephalitis (FSME, meningitis), ehrlichiosis, tularemia and rickettsiosis. Leishmaniasis and dirofilariosis are transmitted by mosquitoes.

The three most important tick species are Rhipicephalus sanguineus (brown dog tick), Dermacentor reticulatus (riparian tick) and Ixodes ricinus (common wood tick). The brown dog tick and the floodplain tick are more common in warmer climates. However, there is a tendency for them to migrate northward: At the moment they can be found in almost all European countries. The common wood tick likes cooler climates and has therefore always been native to central and northern Europe. The Mediterranean region is too warm for this species. Apparently, vectors such as fly and mosquito species also migrate northward, e.g., Culicoides mosquitoes, the vectors of bluetongue.
All these diseases have been around for a long time, but in recent years there has been an increase in contagions, especially in dogs and cats. On the one hand, climate change could be to blame for this circumstance: With the warmer weather, the vectors and with them the pathogens are migrating northward. On the other hand, increased vacation trips to more exotic destinations with “animal appendages” play a significant role.

Most of the diseases listed are not curable. That is why a good precaution, e.g. anti-tick/mosquito medication or collar for dogs/cats, is extremely important.

Lyme disease

Lyme disease (Lyme borreliosis) is a bacterial disease caused by bacterial species (spirochetes) belonging to the Borrelia burgdorferi complex. Transmission occurs through the wood tick, a tick species of the genus Ixodidae. The bacteria can affect the brain, joints, all internal organs and tissues. Not all infected animals develop clinical signs.

Clinical manifestations in dogs include fever, lameness, listlessness, lymph node swelling and lassitude, and less commonly behavioral changes, seizures, encephalitis, kidney problems, cardiac arrhythmia and reproductive disorders. In horses, abortions, laminitis and weight loss occur, and less frequently neurological changes (encephalitis) and blindness (eye inflammation).

Ehrlichiosis (Anaplasmosis)

Ehrlichiosis is a major tick-borne (brown dog tick) disease with worldwide distribution (mainly tropics, subtropics, Mediterranean region). The disease is caused by bacteria (obligate intracellular) of the genus Ehrlichia, which reside in cells. The pathogen can survive in the ticks for up to five months. Certain anaplasmas are also transmitted by the wood tick (Ixodes).

Symptoms in the infected animal are usually nonspecific and varied. Due to the colonization of part of the white blood cells, there is a poverty of white blood cells (leukopenia) and platelets (thrombocytopenia). In the acute clinical picture, fever, depression, dyspnea, loss of appetite, and weight loss are present; later, lymph node swelling, spleen/liver enlargement, hemorrhage, nosebleeds, edema, eye changes, and possibly neurologic symptoms are seen. Often the infection is complicated by additional diseases.

Infections of humans by ehrlichia do occur, but most likely only by tick transmission. Dog-to-human transmission is unlikely. This disease used to be a typical travel sickness. However, it is possible that this tick is now spreading in Switzerland and Germany.

Rickettsial fever (spotted fever)

Rickettsialpox is also a disease caused by bacteria. Dogs are particularly affected by Rocky Mountain spotted fever and Mediterranean spotted fever. Rocky Mountain spotted fever (USA, Central and South America) is caused by several different ticks acting as vectors. In Mediterranean spotted fever (southern Europe, Middle East, South Africa), the main vector is thought to be the brown dog tick.

The clinical picture in the dog varies, the following symptoms occur: Fever, loss of appetite (anorexia), listlessness, immobility, edema, swelling of the lymph nodes, neurological changes, pinpoint hemorrhages (petechiae), and sometimes the redness characteristic of humans.

Apart from dogs and humans, various other mammals are also affected by rickettsialpox (cat, cattle, sheep, goats, rodents, wild ruminants, horses).

Tularaemia (rabbit plague)

The disease is caused by the bacterium Francisella tularensis. The pathogen is transmitted by blood-sucking parasites that live on the surface of the body, such as mosquitoes, fleas, lice, bedbugs, mites or ticks. Shortly after infection, septicemia (pathogen spreads throughout the body via the blood) occurs. The animals show weakness, fever, increased respiratory rate, and lack of escape behavior. Lymph nodes and spleen are enlarged. Rabbits usually die of blood poisoning within four to thirteen days. Other species are less susceptible or resistant. In rare cases of infection, distemper-like symptoms may occur in dogs, for example.

Babesiosis

Babesiosis is caused by parasitic protozoa (single-celled parasites) of the genus Babesia, which occupy red blood cells. The parasites destroy red blood cells, causing anemia (hemolytic anemia) and jaundice. The disease is usually severe. Babesia is transmitted by ticks of the family Ixodidae (wood ticks). There are many different types of babesia that cause disease in different animals.

Clinical symptoms (e.g., fever, listlessness, weakness, bloody urine, circulatory collapse, multiple organ failure) vary in severity depending on the type of babesia.

Leishmaniasis

The main causative agent of leishmaniasis is Leishmania infantum, a blood parasite belonging to the protozoa. Leishmania require two hosts to develop, an insect host (sandfly) and a vertebrate host (e.g. dog). Canine leishmaniasis is a serious chronic disease that occurs in the Mediterranean region, in Asia and Latin America, but is sometimes suspected to be present in Ticino. The disease often occurs in imported dogs or as an unwanted “vacation souvenir”. The clinical presentation is variable, ranging from skin and eye changes to weight loss, lymph node swelling, lameness, nosebleeds and diarrhea. Most noticeable are typical “spectacle-like” skin changes around the eyes.

Dirofilariosis (heartworm disease)

Dirofilariosis is a serious disease caused by roundworms (nematodes: Dirofilaria immitis). For its development, the pathogen requires two hosts, an insect host (mosquitoes) and a vertebrate host (dogs). The pathogen (worm larvae) is transmitted by a mosquito bite. Thereafter, the worm larvae migrate through the tissues in the dog and eventually the adult worms settle in the right ventricle and pulmonary arteries. Due to the localization of the worms in the heart, clinical symptoms such as poor performance, cough, weight loss, heart enlargement, shock and sudden death occur months to years after infection.

Dirofilariosis does not occur in our latitudes and is therefore a typical travel disease, which is unfortunately brought home from time to time.

Early summer meningoencephalitis (TBE)

This is an inflammation of the meninges and brain caused by viruses (Flaviviridae), which leads to a fatal disease, especially in humans. The pathogen is transmitted by ticks of the genus Ixodes (wood tick). Wild ruminants such as deer or roe deer develop antibodies in the blood but do not show a clinical picture. Antibodies have also been found in horses.

Isolated cases in dogs with fever, clouding of consciousness, paralysis and cranial nerve failures have been described, but overall they are not very susceptible. However, as infections in humans have recently become more common, an increase in infections in dogs and possibly horses must also be expected. Vaccination for dogs (and other animals) does not exist.

Tick prophylaxis

The pathogens that cause Lyme disease or early summer meningoencephalitis are only gradually transmitted to the host during a tick bite. Professional removal of the tick within 24 hours therefore minimizes the risk considerably.

Protection

This is how you protect yourself in the wild:

  • Wear long pants and tops in bright colors when walking or working in the garden. This makes it easier to spot a tick crawling around on clothing in search of a suitable puncture site.
  • During walks, avoid excursions into high grass or undergrowth, as ticks prefer to stay there.

This is what you should do when you come back from outside:

  • Thoroughly search your clothes for ticks and shake them out well.
  • Take a shower and search your body well. Ticks need thin skin for a bite, so they prefer to stay in the back of the knees, the groin area, at the hairline and behind the ears.
  • Thoroughly comb through your pet’s entire coat after each walk. Especially in breeds with longer fur, ticks can hide well. Cats should also be checked for ticks after each outdoor visit.
  • Already attached ticks can be removed by means of a tick card or special tick forceps. Twist the tick slightly while pulling it out, this minimizes the risk of tearing off parts of the mouthparts and leaving them in the skin.

There are various preparations available from your veterinarian, which provide reliable and safe protection against ticks. For dogs there are various collars, tablets as well as spot on preparations, which are applied to the skin on the back of the neck. For cats there are also collars and spot on preparations. These products differ in their application and can be dosed according to the body weight of the animal. Your veterinarian will be happy to advise you!

Sources

Source: Based on an article from weltdertiere.ch; with additions by Dr. med. vet. Carmen Meichtry, Site Manager MeikoVet Small Animal Practice Lyssach

1. emerging arthropod-borne diseases of companion animals in Europe. Beugnet F, Marié JL. Vet Parasitol. 2009 Aug 26;163(4): 298-305.

2 Vector-borne diseases in humans and animals: activities of the Swiss Tropical Institute and risks for Switzerland. Zinsstag J, Schelling E. Schweiz Arch Tierheilkd. 2003 Dec;145(12): 559-66, 568-9.

3. canine ehrlichiosis. Skotarczak B. Ann Agric Environ Med. 2003;10(2): 137-41.

4. seroprevalence of anti-Borrelia burgdorferi antibodies in dogs and horses in Turkey. Bhide M, Yilmaz Z, Golcu E, Torun S, Mikula I. Ann Agric Environ Med. 2008 Jun;15(1): 85-90.

5th Pathologic Bassis of Veterinary Disease, M.McGavin, J. Zachary, Elsevier, ISBN 978-0-323-02870-7.

6. medical microbiology, infection and epidemiology, Michael Rolle, Anton Mayr. 8th ed. Enke Verlag, Stuttgart 2006, ISBN 978-3-8304-1060-7

Other sources:
www.medizin-aspekte.de, www.wikipedia.org