HomeMagazinesProtect your livestock from two-host ticks

Protect your livestock from two-host ticks

Estimated reading time: 5 minutes

  • Ticks are small, external parasitic arachnids that belong to the superfamily Ixodoidea. When people or animals are bitten by these parasites they sometimes have to pay a high price, as these bloodsuckers can transmit serious diseases. 
  • There are three noteworthy types: one-host (all three stages on one animal), two-host (larva and nymph on one animal, adult parasite on another animal), and three-host (each stage of the parasite is on another host).
  • Although there are several different two-host tick species worldwide, the red-legged (Rhipicephalus evertsi evertsi) and bont ticks (Amblyomma hebraeum) are considered the most important species in South Africa, with mostly only the adult ticks visible on animals.
  • Producers must check their livestock regularly, especially the preferred attachment sites.

Ticks are small, external parasitic arachnids that belong to the superfamily Ixodoidea. When people or animals are bitten by these parasites they sometimes have to pay a high price, as these bloodsuckers can transmit serious diseases. 

There are three noteworthy types of ticks: one-host (all three stages on one animal), two-host (larva and nymph on one animal, adult parasite on another animal), and three-host (each stage of the parasite is on another host).

The tick’s life cycle

“Although there are several different two-host tick species worldwide, the red-legged (Rhipicephalus evertsi evertsi) and bont ticks (Amblyomma hebraeum) are considered the most important species in South Africa, with mostly only the adult ticks visible on animals,” says Dr Tom Strydom, global technical director of antiparasitics and reproduction at MSD Animal Health.

Bont-legged ticks attach themselves to the skin between the claws of animals, which may culminate in lameness and foot abscesses, especially in small stock.

He breaks down the life cycle of two-host ticks as follows:

  • The larvae of two-host ticks use their mouthparts to pierce the skin of the animal, feeding on the host’s blood for five to seven days. During this period the larvae moult and develop into a nymph.
  • After the larval stage, the tick nymph feeds for five to seven days, during which time it increases in size and falls off its host.
  • The nymph moults on the ground and, if conditions are favourable, develops into an adult male or female tick – this may take several months.
  • Adult ticks can survive on grazing for up to five or six months without having to feed. As soon as a host passes by, the ticks climb onto it and start feeding on the host’s blood.
  • Female ticks feed on the host for between five and ten days. Once engorged, she falls off the host and proceeds to lay her eggs (between 5 000 and 15 000) after a few days or weeks. This process can take several months, depending on the species and environmental factors.
  • The next generation of larvae that hatch from the eggs usually prefer small goats, rodents and birds, but will also feed on any other warm-blooded animal.

Producers need to stay alert, especially during the warmer summer months as ticks are most active during this period and tick loads (adult stage) on animals can be particularly high.

Read more about spring and summer diseases here.

Species and diseases

According to Dr Strydom, the bont-legged tick favours the warmer, drier parts of the country. One of the major diseases this tick causes is a tickborne toxicosis known as sweating sickness. Their long mouthparts also cause severe tissue damage, and this tick is also responsible for the acute and highly contagious viral disease, Congo fever, in humans. Red-legged ticks are found countrywide and can transmit African redwater to their hosts.

While these are the main diseases these two tick species transmit in South Africa, there are other bacterial and viral infections, as well as protozoan diseases, they are responsible for. “The thing to keep in mind is that all ticks are bloodsuckers and the higher the tick load on an animal, the higher the chances of that animal becoming anaemic,” says Dr Strydom.

“Their bites damage the skin, and this reduces the value of skins. In addition, the long mouthparts of ticks such as the bont-legged and bont tick (heartwater tick) may lead to severe wounds and abscesses. Bont-legged ticks attach themselves to the skin between the claws of animals, which may culminate in lameness and foot abscesses, especially in small stock.”

Adequate control

Producers must check their livestock regularly, especially the preferred attachment sites, advises Dr Strydom. Adult bont-legged ticks favour the ventral parts of the body, parts of the body with less hair such as on the udder and teats of cows, the sheath and testes of bulls, in the groin area, under the front legs and, as mentioned, between the claws of animals. Pay attention to high tick loads on the tail switch and under the tail, which is a favourite spot for adult red-legged ticks.

Treatment against tick infestation and its control, especially during the summer months, includes the use of products containing synthetic pyrethroids, amitraz or organophosphates. However, be cautious of organophosphate as it is fatal to oxpeckers. Try to limit its use in areas in which these birds occur. – Carin Venter, Stockfarm

Send an email to Dr Tom Strydom at tom.strydom@msd.com for more information.

Must Read

Swellendam-skou gaan van krag tot krag

Estimated reading time: 6 minutes Hierdie jaar het die Swellendam-skou 'n merkwaardige 192ste viering beleef. Dié skou spog met die grootste streekjeugskou in die...