Ticks: Life Cycle and Disease Transmission

Ticks: Life Cycle and Disease Transmission

Ticks are a typical external (on the skin) parasite of numerous animals, consisting of dogs.

What are ticks?

Ticks are not bugs like fleas, flies, and lice, however are arachnids like termites and spiders. There are approximately 850 types of ticks worldwide. Researchers have categorized ticks into two families based upon their structure: Ixodidae and Argasidae.

Ixodid ticks

The tick household Ixodidae consists of ticks that have a hard external covering called a ‘scutum’ and therefore, are called ‘hard-shelled ticks’. Table 1 notes the most important hard-shelled ticks for dogs and cats.

Argasid ticks

The family Argasidae includes the argasid ticks, which are soft-shelled. Their body does not have a scutum. An argasid has its head situated ventrally (on the underside of its body) and when the tick is seen from above, the head can not be seen.The soft-shelled ticks or Argasids are fewer in number. The one most understood is Otobius megnini, also called the Spinose Ear Tick. It is most typical in the Southwest and usually attaches to the ears of animals.

Table 1: Ticks commonly found on dogs and cats

Tick Common Name Geographic Distribution in U.S. Tick-associated Disease(s)
in Dogs and Cats*
Amblyomma americanum Lone star tick Southeast, Midsouth and coastal Northeast Ehrlichiosis, tularemia, Rocky Mountain spotted fever, tick paralysis
Anblyomma maculatum Gulf Coast tick Gulf Coast to Midsouth and lower Midwest Hepatozoonosis
Dermacentor variabilis American dog tick Eastern 2/3 of U.S.; West Coast Ehrlichiosis, tularemia, Rocky Mountain spotted fever, cytauxzoonosis, tick paralysis
Dermacentor andersoni Rocky Mountain wood tick Northwest; Northern Rocky Mountain states Rocky Mountain spotted fever, tularemia, cytauxzoonosis, tick paralysis
Ixodes scapularis Eastern black-legged tick (deer tick) States east of and adjacent to Mississippi River; Eastern TX and OK Lyme disease, anaplasmosis, tick paralysis
Ixodes pacificus Western black-legged tick West Coast and Eastern NV Lyme disease, anaplasmosis
Rhipicephalus sanguineus Brown dog tick Throughout U.S Ehrlichiosis, Rocky Mountain spotted fever, babesiosis, anaplasmosis, hepatozoonosis, haemobartonellosis

What are the physiological functions of ticks?

All ticks have three pairs of legs during the immature stage and 4 pairs as an adult. They crawl however can not fly because they have no wings. Ticks have a sensory apparatus called ‘Haller’s organ.’ This structure senses smell, heat, and humidity. This is how the ticks find their food source. They climb up upon high turf when they sense an animal is nearby, they crawl on.

What do ticks eat?

A tick’s diet includes blood and only blood. The tick imbeds its mouthparts into the animal’s (or human’s) skin and sucks the blood. Other than for the eggs, ticks require a blood meal to progress to each successive stage in their life cycle.

What is the life process of a tick?

Many ticks are what we call 3 host ticks, that is, during their advancement which takes two years, they feed upon 3 various hosts. All ticks have four stages to their life cycle: egg, larvae (seed tick), nymph, and adult. Let us take a look at the life cycle of the deer tick, as an example.

Adult female deer ticks ordinary eggs on the ground in spring. Later on in the summer season (depending upon moisture and temperature), the eggs hatch into larvae. The larvae, which are smaller sized than the period at the end of this sentence, discover an animal (the first host, which is usually a bird or rodent), live off its blood for numerous days, then separate and fall back onto the ground. For deer ticks, this most typically takes place in the month of August. In the ground, the well-fed larvae now molt into the next stage and are called nymphs.

The nymphs remain inactive during the winter months and in spring become active. The nymph now discovers an animal (the second host – a rodent, family pet, or human) and feeds again. Once well fed, the nymph removes and falls back to the ground. Here it molts and changes into a grownup. Throughout the fall, both adult male and female ticks now discover another animal (the third host – a rodent, deer, animal, or human) and feed upon blood and mate. When well fed, both males and females fall back to the ground. The male now dies and the female lives through the winter and lays eggs in the spring, completing the cycle. If the grownups can not find a host animal to feed on in the fall, they will endure in the leaf litter up until the next spring when they will feed, mate, and produce eggs.

Other types of ticks might be at peak activity for each life stage at various times of the year than the deer tick we explained. Your regional university or health department may have information on peak tick activity in your area.

What diseases do ticks send?

Ticks can transfer or cause:

  • Anaplasmosis
  • Babesiosis (Piroplasmosis)
  • Cytauxzoonosis
  • Ehrlichiosis
  • Haemobartonellosis in Dogs and Cats
  • Hepatozoonosis
  • Lyme Disease
  • Rocky Mountain Spotted Fever
  • Tick Paralysis
  • Tularemia in Dogs and Cats

Also read: Natural Home Remedies For Fleas and Ticks On Dogs and Cats

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