How worried should we be about ticks?

For many people, spring has well and truly arrived. The time is now right to enjoy the outdoors and to roam freely in the woods and the long grass. But be wary! It is not just humans that like to get out and about at this time of year...

Wooded and bushy areas with high grass and leaf litter are favored habitats of ticks.

An onset of Lyme Disease may disrupted people's lives that may leave them bedridden for several months.

It seems strange that something as seemingly innocuous as a tick, often close in size to a pinhead, could damage someone's health to the extent that they are fearful for their life. 

In 2013, the Centers for Disease Control and Prevention (CDC) report that there was a total of 27,203 cases of Lyme disease confirmed in the USA.

This figure does not tell the whole story when it comes to ticks, however. 

Although closely associated with Lyme disease, these small arthropods are capable of carrying a wide variety of other pathogens that can cause human disease.

How worried should we be? In this Spotlight feature, we place the diminutive tick under the microscope and find out how much of a danger to health these little bugs can be, as well as what steps should be taken if you are unfortunate enough to be bitten by one.

What are ticks?

Although they look similar to both insects and spiders, a tick is neither of these two creatures. Ticks are arthropods - invertebrates with jointed legs - that belong to the same class of arachnids as mites. They are small external parasites that feed purely on the blood of other creatures.

There are two main kinds of tick: hard ticks (ixodidae) and soft ticks (argasidae). The difference between the two is that hard ticks are protected by a hard protective plate on their backs that restricts the rate at which they can feed. Soft ticks are more leathery and are unrestricted by a protective plate, enabling them to feast more quickly.

Some ticks will only feed on a particular type of animal, while some are far less selective and will happily feed on other creatures if their regular host animal is unavailable. As well as between different species, the feeding habits of ticks can vary across the four stages of their life cycle: egg, larva, nymph and adult.

Ticks are typically very small and can be quite difficult to spot if they are not actively searched for, particularly in places such as the armpits and in the hair.

Ticks locate potential hosts by detecting breath, odors, body heat, moisture, vibrations and even shadows in some cases. 

As ticks are unable to fly or jump, they wait for hosts on the tips of grasses and shrubs in a position known as "questing." When questing, ticks hold onto the grass or shrub with their back pairs of legs while their first pair of legs is outstretched, ready to climb onto a host when they brush past.

When feeding, ticks do not burrow into the skin. 

Rather, a tick will grasp the surface of the skin and insert its feeding tube. Some tick species will secure themselves further with barbs on their feeding tubes, or by secreting a cement-like substance.

Ticks can be very difficult to notice if you are not actively looking for them. In addition to being quite small, ticks can also secrete saliva with anesthetic properties, numbing the area where the tick is feeding and preventing the host from feeling that the tick has attached itself.

Once attached, a tick will begin to feed. The amount of time taken to feed varies between species, but hard ticks can take as long as several days to feed fully. When most ticks finish feeding, they drop off of their host and prepare for the next stage of their life cycle.

While tick bites can provide a small amount of discomfort, the real danger with ticks comes from the pathogens that some ticks carry. If feeding on a host animal with a bloodborne infection, ticks can ingest the pathogens along with the blood. These pathogens can then be transmitted to other hosts the next time a tick attaches itself to feed.

Ticks and Lyme disease

Ticks are almost synonymous with Lyme disease, a bacterial infection characterized by fatigue, fever, headaches and a skin rash (these symptoms are common to many tickborne diseases). Untreated, Lyme disease can spread through the body, affecting the heart, joints and nervous system.

As a bacterial infection, Lyme disease is frequently treated with antibiotic medication such as doxycycline or amoxicillin. If the disease is allowed to develop over a course of several weeks, patients may require the administration of intravenous antibiotics, depending on the severity of the disease's progression.

However, being on the receiving end of a tick bite is by no means a guarantee that Lyme disease has been contracted. The chances of catching Lyme disease depend on a number of factors, including the type of tick that has been encountered and the length of time for which it was feeding.

Specifically, Lyme disease bacteria are only transmitted in the US by blacklegged ticks, also known as deer ticks. Ticks are not born carrying Lyme disease pathogens and will only acquire the infection after feeding on an infected animal - typically a mouse. For this reason, larval deer ticks will not transmit these pathogens.

Blacklegged ticks are only located in specific areas of the country. The CDC report that most Lyme disease infections are found in these endemic locations:

• North-central states, mainly Wisconsin and Minnesota
• Northeast and mid-Atlantic areas, from northeastern Virginia to Maine
• The West Coast, particularly northern California.

In 2013, 95% of confirmed Lyme disease cases in the US were reported in just 14 states: Connecticut, Delaware, Maine, Maryland, Massachusetts, Minnesota, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, Vermont, Virginia and Wisconsin.

Being bitten by a blacklegged tick in one of these states still does not guarantee the transmission of Lyme disease. A tick carrying the Lyme disease pathogens needs to be attached for at least 36-48 hours before the bacteria are transmitted. Removing a tick promptly after being bitten greatly reduces the risk of acquiring the disease.

The disease was first recognized in the Lyme area of Connecticut in 1975 and takes its name from here. However, although Lyme disease is the most common tickborne illness in North America and Europe, it is not the only one. Recently, news reports have suggested that one such disease is beginning to emerge in this northeastern state.

Other ticks, other diseases

Although it shares many symptoms with Lyme disease, the Powassan virus differs in that there is no treatment currently available for it. According to clinicians at the Connecticut Agricultural Experiment Station, the virus can be fatal in some cases.

Ticks should be removed promptly upon discovery. Although specialized removal equipment is available, a regular pair of tweezers should suffice.

Powassan virus can also be transmitted much quicker than Lyme disease. "These ticks will transmit this virus when they feed within a matter of hours, whereas with Lyme disease, for example, ticks generally have to feed up to 2 days before they're capable of transmitting it.

There have yet to be any reported human cases of the virus in this region, but people should be more careful than ever when venturing into woodland environments that could be home to ticks carrying these pathogens.

Lyme disease and Powassan virus are not the only conditions that can be spread by the blacklegged tick. Other diseases transmitted by this species include anaplasmosis and babesiosis.

Of course, blacklegged ticks are not the only species of tick known to spread disease to humans. Across the US, for instance, a number of different species can be found that carry a variety of different pathogens potentially dangerous to humans.

The lonestar tick is a repeat offender when it comes to spreading disease. Found in southcentral and eastern states in the US, this hard tick can carry pathogens that cause diseases such as ehrlichiosis, southern tick-associated rash illness (STARI) and tularemia. Recent studies suggest that they may also transmit heartland virus.

Another tick to look out for is the Rocky Mountain wood tick, found in the Rocky Mountain states at elevations of 4,000 to 10,500 feet. These creatures can carry pathogens that cause Colorado tick fever, Rocky Mountain spotted fever (RMSF) and tularemia.

It is not just the slow-feeding hard ticks that can carry harmful pathogens either. Tick-borne relapsing fever (TBRF) is transmitted by swifter soft ticks and cases have been reported in 15 states so far: Arizona, California, Colorado, Idaho, Kansas, Montana, Nevada, New Mexico, Ohio, Oklahoma, Oregon, Texas, Utah, Washington and Wyoming.

These examples illustrate the fact that although Lyme disease typically occurs in very specific areas of the US, there are other tickborne diseases that can be found in other areas, so long as the environment is suited to the ticks.

Preventing and treating tick bites

There are a number of precautions that can be taken in order reduce the chances of a tick attaching, feeding and potentially transmitting an infection. When questing, ticks are most likely to be found in wooded and bushy areas, with high grass and leaf litter, so either avoid or be cautious in these types of environment.

Clothing can provide some protection from ticks. Wearing long-sleeved tops can protect the arms, and tucking pant legs into socks and boots can prevent ticks from having easy access to legs. Repellents are also available that can be applied to both skin and clothing. Those containing 20-30% DEET (N, N-diethyl-m-toluamide) offer several hours of protection.

After being out in an environment that could be home to ticks, it is recommended that you conduct a full-body tick check, especially as it is hard to notice them without actively searching.

As stated before, prompt removal of ticks is crucial to reducing the risk of infection. Although specialized tick removal devices are available, a regular pair of fine-tipped tweezers is more than adequate.

Using the tweezers, grasp the tick as close to the surface of the skin as possible. With steady, even pressure, pull upwards. Twisting and jerking the tick can cause some of its mouth-parts to remain embedded in the skin. If this occurs, carefully attempt to remove the remaining parts with the tweezers.

Once removed, clean the affected area and your hands, and dispose of the tick by submersing it in alcohol, placing it in a sealed container or disposing of it down the toilet. Do not crush a tick with your fingers.

Ticks are most active in the warmer months, between April and September, so now is the time to be particularly wary of these questing bugs. 

Although ticks are capable of spreading harmful diseases, with proper caution, these little beasties should not prevent you from being able to enjoy the great outdoors.

References:

1.     CBS New York, Untreatable virus found in ticks in southern Connecticut, accessed 15 April 2015.

2.     CDC, Data and statistics, accessed 15 April 2015.

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4.     CDC, Lyme disease, accessed 15 April 2015.

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6.     CDC, Preventing tick bites, accessed 15 April 2015.

7.     CDC, Reported cases of Lyme disease by state or locality, 2004-2013, accessed 14 April 2015.

8.     CDC, Tickborne diseases of the U.S., accessed 15 April 2015.

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10.   Department of Public Health, A brief history of Lyme disease in Connecticut, accessed 15 April 2015.

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15.   People, Avril Lavigne opens up about her health crisis: 'I was bedridden for 5 months,' accessed 14 April 2015.