PULLMAN, Wash. – A mild winter coupled with warming weather in the Pacific Northwest has brought a renewed threat of tick paralysis in animals and people. Tick paralysis is a somewhat uncommon but potentially fatal disease. It can affect virtually all warm-blooded land animals including humans – usually children. Paralysis occurs when certain species of ticks inject potent toxins from their salivary glands into the host.
The disease was first identified in Australia in 1824. Since then, more than 60 species of ticks worldwide have been identified as toxin producers.
At least two prominent species of ticks on the list of toxin producers are native to North America, including the Pacific Northwest. In fact, tick paralysis occurs most in the northwestern and southeastern regions of North America along with the east coast of Australia and southern Africa.
Globally, ticks are second only to mosquitoes as disease vectors, transmitting many different microorganisms. In North America, ticks actually transmit more disease than mosquitoes.
“All medical professionals, human and animal, know tick paralysis is a serious, potentially fatal illness,” explained Professor Steve Parish, a veterinarian and former head of the Washington State University Veterinary College’s Agricultural Animal Service.
“Llamas and alpacas, the New World camelids, seem to be particularly susceptible to the effects of the toxin and we don’t know why,” said Parish, who has consulted on one case of tick paralysis and treated another already this spring.
Each spring and summer, WSU’s veterinary teaching hospital sees or provides consultation on several cases of tick paralysis in llamas and alpacas in particular. The cases come from throughout the Northwest.
Occurrence of the disease is sporadic and difficult to predict because the toxin does not occur in all tick populations all of the time or in the same local regions. And only female ticks attach firmly and engorge on blood from the hosts to inject the toxin.
“Symptoms of tick paralysis include a rapidly progressing total paralysis over 24 to 72 hours after the ticks attach themselves to the animal,” Parish explained. “Untreated, an animal may be unable to chew, swallow, drink or breathe as the paralysis progresses to the respiratory system. Obviously, if the breathing mechanism is paralyzed, the animal dies.” Untreated, death rates for tick paralysis have been reported as high as 10 percent or more in humans and around seven percent in domestic animals. Interestingly, medical literature shows that, in most human cases of the disease, only a single tick was found on the patient.
“As dire as this disease sounds though, treatment is effective and reversal of the paralysis can be rapid with an excellent prognosis,” said Parish. “The key is to remove the ticks as a source of the toxin and provide supportive care.”
Recovery occurs in most animals and people within 48 hours, but llamas and alpacas seem to be hit a bit harder for reasons not well understood: “Their complete recovery could take up to several weeks,” said Parish.
Recovery occurs in most animals and people within 48 hours, but llamas and alpacas seem to be hit a bit harder for reasons not well understood: “Their complete recovery could take up to several weeks,” said Parish.
In the case of llamas and alpacas, removing all the ticks may require the animal be shorn and treated with a medication that kills any ticks still attached.
Ivermectin, a drug used to kill parasites in many species, is effective when used in the proper dosages and with the consultation of a veterinarian. In addition to tick removal and ivermectin, it may also be necessary to use external chemical insecticides, again under consultation with a veterinarian.
Tick repellants will help prevent ticks from attaching to animals and people.
WSU veterinarians recommend that ticks are best removed with curved tweezers, forceps or gloved fingers. The tick should be grasped close to the skin and pulled with steady but gentle traction to ensure all the mouth parts come off with the entire tick.
Folklore removal methods such as applying a lighted match or petroleum jelly to the tick are not effective.
As with any other potentially infectious source, people should always wash their hands thoroughly with soap and water.