What is Tick Paralysis?
Tick paralysis is a rare neurological condition which is not infectious and results in sudden difficulty in walking, progressing to a full body paralysis. It’s caused by a toxin present in the saliva of certain tick species. The symptoms can often be confused with another neurological disorder called Guillain-Barre syndrome. This type of tick paralysis is most commonly found in North America and Australia.
If identified and treated early, patients usually make a complete recovery just by removing the tick and providing supportive care. However, if not treated, it could progress to severe breathing difficulties, and even death.
It’s important for healthcare providers to be aware of this rare but treatable cause of sudden muscle weakness. They need to be suspicious of this condition to avoid delays in diagnosis and treatment. In particular, tick paralysis should be considered whenever someone suddenly develops difficulty walking, especially in children.
What Causes Tick Paralysis?
Tick paralysis is linked to over 40 different types of ticks. In North America, the majority of cases involve a group of ticks known as Dermacentor. The most common members of this group causing this condition are the American dog tick (Dermacentor variabilis) and the Rocky Mountain wood tick (Dermacentor andersoni). Other ticks, such as the Lone Star tick (Amblyomma americanum) and the black-legged tick (Ixodes scapularis), can also cause this disease. In Australia, the scrub tick (Ixodes holocyclus) is most often the cause.
Tick paralysis occurs when a fully-fed female tick releases a special type of poison from its saliva that can cause paralysis. The effects of the poison can vary, depending on the specific type of tick.
Risk Factors and Frequency for Tick Paralysis
Tick paralysis was initially identified in Australia in the 19th century, but since then cases have been found in several regions, including Argentina, Canada, and various parts of the United States. Both humans and pets can be affected by it. This illness, like many diseases spread by ticks, is most common in the spring and early summer.
The disease seems to occur more often in children, which might be due to their smaller body size making the tick’s toxin more potent. It might be more widespread among females because ticks can be hidden and go unnoticed in long hair. Unfortunately, recording the data for tick paralysis is not always compulsory, so there is a lack of reliable information on how often it happens and where it is most prevalent.
Signs and Symptoms of Tick Paralysis
Tick paralysis often begins with tiredness and weakness, which then develops into clumsiness and a gradually increasing paralysis that starts from the legs and moves upwards. Some individuals may also experience symptoms such as irritability, muscle discomfort, or strange sensations in their skin. Notably, there aren’t usually any symptoms of a fever, rash, headache, or changes in mental states. Despite these skin sensations, a general sensory examination typically comes back normal. This condition might involve muscles controlled by the cranial nerves, which can sometimes result in the pupils of the eyes dilating. If the paralysis reaches the muscles responsible for breathing, it can lead to severe respiratory issues, even death.
It is rare for patients to recall a previous tick bite, thus a thorough physical examination, especially focusing on the scalp, armpits, spaces between fingers and toes, and the perineum is crucial for diagnosis. It’s worth noting that ticks can be easily overlooked by medical professionals and are often discovered by caregivers or other healthcare personnel. It’s also possible for patients to have multiple ticks attached.
One common misdiagnosis is Guillain-Barre syndrome, a condition that often shares similar symptoms. Therefore, if a diagnosis of Guillain-Barre syndrome is being considered, it’s crucial to also search for ticks to avoid unnecessary and costly treatments like plasmapheresis or immune globulin, which won’t be effective against tick paralysis. Compared to Guillain-Barre or Miller-Fisher syndrome, tick paralysis often develops more swiftly.
Testing for Tick Paralysis
If you have a certain condition caused by a tick bite, imaging tests of your brain and spinal cord, like an MRI or a CT scan, usually show no abnormal results. The exception is if they happen to find a tick that was missed during a physical exam. Another common test, the white blood cell count, which measures the number of disease-fighting cells in your blood, is also usually normal, as is the analysis of cerebrospinal fluid, which is the fluid in and around your brain and spinal cord.
However, if your lungs are affected by this condition and you’re having trouble breathing, you may have tests to measure how well your lungs are working and to check the levels of gases in your blood. These tests are crucial because they can help your doctor decide if you need a breathing tube and assistance from a ventilator machine to help you breathe.
Another type of test, known as electromyography, which checks whether the muscles are responding correctly to nerve signals, may show lower than usual results. This suggests that the nerves are not communicating well with the muscles. Another nerve test, known as repetitive nerve stimulation, which measures how well your nerves can send signals, is typically normal in this condition.
Treatment Options for Tick Paralysis
If you get bitten by a tick, the first step towards treatment is to remove it. The best method to do this is by using a pair of fine-tipped tweezers to pull the tick gently and steadily, upwards and outwards from the skin. You need to be careful not to leave any parts of the tick’s mouth in the wound. It’s important to note that in severe cases, breathing assistance might be required.
The best form of protection against diseases transmitted by ticks is to prevent tick bites altogether. Unfortunately, apart from tick-borne encephalitis, no vaccines are available for other diseases caused by ticks. Therefore, when in areas prone to ticks, especially in late spring and summer which are peak tick seasons, you should wear protective clothing like long pants and long-sleeved shirts and closed shoes. When walking through tall grass and brush, it’s a good idea to tuck your pant legs into your socks. Also, you may use tick repellents. One such repellent is Permethrin, an insecticide that can be applied to clothing to repel ticks effectively. You could also use DEET on your skin or clothes, but its effectiveness varies, and it can be toxic, causing skin irritation and even seizures in some cases. It’s advised not to use DEET on infants.
For people suffering from paralysis caused by tick bites (specifically from the Dermacentor species), they typically recover fully within hours after tick removal. However, for bites from the Australian Ixodes holocyclus tick, the weakness and paralysis may worsen within the first 24 to 48 hours after the tick has been removed. Those cases may need to stay in the hospital for observation and breathing assistance if needed.
What else can Tick Paralysis be?
When a doctor is trying to diagnose tick paralysis, they also consider other conditions that could cause paralysis. These include:
- Guillain-Barre syndrome
- Botulism
- Polio (poliomyelitis)
- Myasthenia gravis
- Conditions causing spinal cord lesions
What to expect with Tick Paralysis
Patients suffering from tick paralysis usually make a full recovery with supportive care and tick removal. There are no long-term effects if tick paralysis is identified and treated. However, if it’s untreated or diagnosed incorrectly, the fatality rate could be as high as 12%.