You may have seen the 1986 psychological horror movie The Hitcher, where Rutger Hauer plays the titular hitchhiker picked up by a well-meaning traveller. The film has the tag line “Once you've met the Hitcher, you'll never pick up another,” as Hauer's character turns out to be a killer.
The plot could easily be applied to experiences with ticks. Ticks are hitchhikers extraordinaire. If you pick up a tick though, it could drink your blood and pass on a very unpleasant disease.
At only 1-4mm long, ticks are tiny members of the arachnid family, so are related to spiders. All ticks feed on the blood of vertebrates, including that of humans, and many tick species have specific hosts.
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Like human hitchhikers, ticks need to find the best place to get a lift. In the tick world, this means climbing grass stems or other vegetation and waiting for an animal to brush by. And rather like hitchhikers 'thumbing a lift' by sticking out a thumb, ticks cling to the vegetation with their hind legs (like spiders, adult ticks have eight legs) and wave their front legs in behaviour known as 'questing'.
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If an animal or human passes within reach, it grabs on tight. Once aboard, it crawls to warm and dark places where it can easily pierce the skin with its mouthparts. As it drinks blood, its body swells to many times its original weight, its bloated abdomen swollen with blood. Once sated, the tick falls off and crawls away to digest its meal.
While losing blood to a tick is never a pleasant experience, the ticks can also introduce bacteria, viruses and parasites during their feeding bouts. Some of these are very serious and may require hospital treatment. So it is always better to prevent a tick infection than to rely on medical treatment afterwards.
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Avoiding tick bites
Ticks are active on warmer days of spring, summer and autumn, so it's advisable to wear long trousers and long-sleeved clothing in areas where ticks are prevalent, such as thick vegetation, particularly long grass, bracken and woodlands.
Insect repellent can also help. And it's important to give your body a thorough check after you've walked through a tick-heavy area. The longer a tick stays on your body, the more chance there is of serious infection.
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If you find a tick, be careful about how you remove it. If you leave the mouthparts in the skin, there is a greater chance of infection. You might need a specific tick-removing tool to complete the job.
There are many diseases associated with ticks – here are nine of the most common.
9 most common tick diseases
Lyme disease
This is a common bacterial infection caused by deer ticks (black-legged ticks). Symptoms include a circular red or purple rash that commonly has a 'bull's eye' red centre, like a target. If not treated with antibiotics, Lyme disease can cause flu-like symptoms, especially fever, headaches and lethargy.
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In some cases, such as with England's 2003 Rugby World Cup winning scrum half Matt Dawson, Lyme disease can lead to longer-term illnesses similar to chronic fatigue.
Ticks infested with Lyme disease can be encountered in grassland and woodland across the Northern Hemisphere.
Rocky mountain spotted fever
Rocky mountain spotted fever (RMSF) is a dangerous bacterial infection spread by ticks (especially species of dog tick) in North and South America. It first appears as a fever and headaches, followed by a blotchy rash with red pinpoints that may bleed.
Without treatment, symptoms rapidly get worse, including nausea, vomiting and stomach pain, and can lead to death. RMSF can be treated with antibiotics but there is a danger of long-term damage if treatment is delayed. This can include loss of hearing, mental impairment and even amputation of limbs.
Colorado tick fever
A rare viral disease spread by the Rocky Mountain wood tick of North America. Symptoms include fever, chills, headaches and fatigue. There are no vaccines or antivirals to treat Colorado tick fever, but most infected people recover within days (though the tiredness can last for weeks). Early pioneers travelling west across the continent knew this disease as 'mountain fever'.
Anaplasmosis
A bacterial disease spread by deer ticks (black-legged tick species). Symptoms take up to two weeks to develop after a tick bite so those affected may not associate them with a tick. These symptoms include chills, fever, headaches, vomiting and diarrhoea, and are easily treated with antibiotics.
Untreated however, the disease can cause severe illnesses including respiratory failure, organ failure and even death.
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Soft tick relapsing fever
Soft tick relapsing fever (STRF) is caused by another bacteria transmitted by 'soft-bodied ticks' of the Genus Ornithodoros (meaning 'bird-like leather sack' – and describes their soft, leathery appearance).
Though these ticks most commonly infest caves and birds' nests where they prey on rodents and birds, they regularly attach themselves to dogs and cats – and humans. Like so many tick-borne diseases, the symptoms are fever, chills, headaches and vomiting. And though these may subside after a few days, they can recur (hence 'relapsing') unless treated with antibiotics.
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STRF occurs in the wilder western parts of North America, the Mediterranean, Middle East and much of Africa.
Babesiosis
This is a parasitic infection spread by deer ticks most common in North America and parts of Europe. The Babesia parasite infects red blood cells and leads to familiar flu symptoms of fever, chills, headaches, fatigue and loss of appetite. But many infected people show no symptoms and are completely unharmed.
In bad cases, Babesiosis can lead to a type of anemia and may be life threatening in people with existing blood disorders or weakened immune systems, causing organ failure and even death. Some antimalarial or antibiotic drugs provide effective treatments.
Tick-borne encephalitis
This is a dangerous but very rare viral infection of the nervous system that can be contracted via tick bites, especially ticks of the Genus Ixodes. It occurs in Europe and much of north-central Asia.
Alongside regular symptoms of fever, headaches and weakness, the disease can, in rare cases, lead to inflammation of the brain (encephalitis) or the membranes around the brain and spinal cord (meningitis), which can be fatal.
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There is a vaccine available for those travelling to at-risk areas but there is no effective antiviral treatment for the disease.
Heartland Virus
Another virus spread by tick bites – primarily by the lone star tick. It is currently very rare and mostly recorded in the US.
Like so many tick-borne illnesses, the symptoms are fever, nausea, diarrhea and vomiting – with muscle pain and bruising added for good measure. It also leads to low blood-cell count (leukopenia), which means sufferers are more at risk of infection. There are currently no antivirals to treat Heartland Virus.
Crimean Congo Haemorrhagic Fever (CCHF)
A deadly virus spread by bites of tick of the Genus Hyaloma, endemic to Africa, the Balkans, Middle East and parts of southern Asia.
Symptoms appear suddenly, beginning with fever, sore eyes, sensitivity to light and muscle pain. This may be followed by confusion and severe mood swings giving way to sleepiness and depression. Sufferers may also experience accelerated heart rates and rashes caused by bleeding up the skin.
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In the worst-case scenarios, patients may have kidney or liver failure, leading to death. There are no antiviral treatments for CCHF and 30% of cases are fatal.
