All about Ticks

Ticks are blood-sucking parasites, which transmit several pathogens of any blood sucking anthropod. There are approximately 850 species of ticks found all over the world. All the species are categorized into two family types – hard ticks and soft ticks.

Hard ticks have three stages in their lifecycle – larva, nymph and adult. Larva emerges from the egg and takes a blood meal from a vertebrate host. It has six legs at this stage. The nymph obtains another blood meal from the host and it has eight legs. Then it enters into the adult stage. The adult female ticks can lay thousands of eggs in one batch and then they die. The interesting fact about ticks is that they can survive without taking blood meal for several months. The questing behavior of these ticks is interesting. The ticks crawl up the stem of grass or settle on the edges of the leaves with the extended front legs. Some biochemical like carbon dioxide, heat and movement stimulate their questing behavior.

Hard ticks obtain blood meal from their hosts for several days, which actually depend on several factors like life stage and host type. The cuticle or outside surface of the ticks grows to accommodate the large volumes of blood.

Soft ticks also have three life stages. The six-legged larva comes out of the egg and takes its blood meal from the host. The soft ticks go through several nymphal stages and then become adults. They feed multiple times during each stage of their lifecycle. The adult female soft ticks lay several eggs in small batches. They can survive without taking a drop of blood. The outside surface or cuticle of soft ticks expand, but does not grow to accommodate the larger volume of blood meals ingested.

Though there are number of tick species, only a few ticks interact with human and domestic animals and do harm to them. Deer ticks are the most common species found on the West Coast of the USA. It is referred to as deer tick, as it has the capability to latch onto the white tailed deer. The adult deer tick females latch onto a host and take blood for four or five days. It becomes engorged and starts laying hundreds of eggs in clusters.

Brown dog tick is another common tick species, which completes its entire lifecycle indoors. It is red brown in color and has an elongated body shape. It prefers to feed on dogs, but can also take blood from humans and domestic animals. Dog tick requires three blood meals during the three stages of its lifecycle. An adult female dog tick lays 5,000 eggs. The number of eggs depends upon the amount of blood ingested by her. These ticks can survive in cooler temperatures as well.

American dog ticks carry bacteria, which is responsible for many diseases. They are the most common hard ticks lone star tick is prevalent in the United States. It is the carrier of various diseases. The female lone star tick can be easily distinguished from their male counterparts, as the females have white dots or star in the center of her back.

Rocky Mountain wood ticks are found in the Rocky Mountains. Wild mammals are the hosts of these ticks. They feed on three different hosts during their lifecycle. The female ticks lay eggs after feeding blood meals. She lays 3000 to 5,500 yellowish brown ellipsoidal eggs within 10 to 33 days. The larvae come from the eggs begin crawling ins search of host within 30 days.

Ticks produce some toxins, which can cause paralysis in animals. It is therefore essential to take steps to eliminate them.

Tick Dangers

Damage caused due to ticks is significant to the human economy. There is a significant reduction in livestock as well as spread of diseases in domestic animals. Ticks transmit viruses, bacteria, protozoa and fungi as agents of diseases to animals. The insects cause physical injury, toxicosis and paralysis. In spite of grooming away the ticks from pets, lesions seem to persist on the skin. The penetration of hard and sharp mouth parts into the skin of the mammal causes damage to tissues and capillaries of epidermis. Paralysis and toxicosis are two major dangers produced by ticks. Patient suffering from paralysis due to female tick bites can return to normalcy by removing the biting parasite. In South Africa, the damage caused due to ticks resulted in disaster as the spring lambs suffered from paralysis by the bite of R.e. mimeticus. Paralysis in poultry is caused by Argas ticks. The toxin segregated from this parasite is processed to get the immunizing dose. Research shows that the chances increase in paralytic cases are high when female ticks suck blood from the mammals in the absence of male ticks.

Some insects like Ornithodoros savignyi cause toxicosis in cattle resulting in death and O. lahorensis affect the sheep in the same way. This is the most devastating damage caused due to ticks in Africa. Cattle in Africa are affected by a disease called sweating sickness which results in excess exudation of serum to the skin surface. In the UK, very young lambs get the disease called tick pyemia caused by the pathogen called Staphylococcus aureus. Rabbits get infested with the same bacteria and die. Scientists feel that the saliva of this parasite consists of immunosuppressive chemicals.