What Diseases Do Ticks Transmit?
As parasitic creatures, ticks pose potentially serious threats to humans and other host animals. Ticks often pass disease-causing pathogens into the bloodstreams of the hosts on which they feed. Common tick varieties often transfer bacteria, parasitic worms, and viruses from an infected host to an uninfected one.
Most notably, ticks are frequent carriers of Lyme disease and Rocky Mountain spotted fever.
Infection can be avoided with the prompt removal of ticks, as the pests may wait up to a day and a half before transferring bacteria to hosts. Other precautionary measures include keeping yards free of overgrown vegetation and wearing pants, long sleeves, and repellents containing DEET or Permethrin when traveling through wooded, grassy areas favorable for ticks.
Rocky Mountain Spotted Fever (RMSF)
Rocky Mountain Spotted Fever (RMSF) is a bacterial infection transmitted by one of the most common ticks, the American dog tick.
Even though the name of the disease is “Rocky Mountain Spotted Fever,” most cases of spotted fever occur in the southern United States. Persons of any age can get RMSF, but about one half of the patients are under 20 years of age. Most cases occur between May 1 and July 31 of each year, the same period in which dog tick populations are at their highest levels. RMSF occurs most commonly in areas where ticks and wild animals are abundant. In it’s immature stages, ticks feed almost exclusively on small rodents such as field mice and meadow voles.
The adult ticks seek larger hosts and are often found on dogs (as their name suggests). Adult American dog ticks will also readily attach to humans.
Symptoms of RMSF Symptoms of RMSF usually appear 3-12 days after tick contact. There is a sudden onset of symptoms which include: fever, headache and aching muscles. A spotted rash usually develops on the wrists and ankles on the second or third day of fever. The rash then spreads to involve the rest of the body, including palms and soles of the feet.
If you experience these symptoms, seek medical If you experience these symptoms, seek medical attention immediately. It is important to receive the appropriate antibiotics as soon as possible once RMSF is suspected.
The fatality rate for RMSF is about 4%. Most fatalities can be attributed to delay in seeking medical attention. If RMSF is recognized and treated early, there is usually a rapid recovery for those who are infected.
Lyme disease is a bacterial infection spread by ticks. In the United States, most cases of Lyme disease occur in southern New England, New York, New Jersey, Pennsylvania, Minnesota, Wisconsin, and the northern Pacific coast.
Early symptoms of Lyme disease present like the flu. Infected individuals may experience fever, chills, sweats, muscle aches, fatigue, nausea, and joint pain.
A distinct bulls-eye shaped rash is often a good indicator of Lyme disease, although it is not necessarily a symptom which always appears. Lyme disease initially produces fever, weakness, headache, chills, and muscle and joint pain, but exhibits later symptoms that include arthritis or meningitis.
Some more serious symptoms include numbness, swollen lymph nodes, muscle spasms, abnormal heartbeats, and cognitive dysfunction.
Though cases can vary from person to person, the average individual starts experiencing symptoms within a few days. If left untreated for too long, the disease can cause permanent damage. Extreme cases end in death.
Treatment & Prevention
Seeking immediate medical attention and receiving a dose of oral antibiotics is usually enough to treat Lyme disease. In order to protect against tick bites in the first place, citizens can follow a number of useful prevention tips.
For example, when hiking, use bug spray and wear close-toed shoes, long sleeves, and long pants. Tucking pants into socks limits the amount of exposed skin, as well. Finally, perform full-body searches before reentering homes after prolonged outdoor activity.
Deer Tick Virus
Closely related to the Powassan virus (POW), the deer tick virus (DTV) is spread by the blacklegged tick and the white-footed mouse. The two viruses differ so little that the only way to know whether an infected person has POW or DTV is through genetic sequencing. Deer tick virus is a danger throughout the United States, as blacklegged ticks are commonly found in conjunction with their main host, the white-tailed deer. As such, residents of areas populated by white-tailed deer should be mindful of tick bites, especially during the end of spring, the start of summer, and the middle of autumn.
The most serious signs and symptoms of deer tick virus generally include a high fever and neurological impairment. Typically, patients experiencing dysfunction of the central nervous system and a fever of 100 degrees Fahrenheit or higher are diagnosed with DTV, barring a more likely explanation of the symptoms. People infected with DTV are also prone to fever, headache, vomiting, weakness, confusion, seizures, and memory loss, though symptoms may or may not appear. Deer tick virus symptoms can start to show as early as one week or as late as one month after first contracting the infection from a tick bite.
Treatment of the deer tick virus usually entails the hospitalization of the infected person, who then receives intravenous fluids, respiratory support, and antibiotics. As DTV can cause long-term neurological damage, staying away from the blacklegged tick is imperative. Avoiding tall grass and wooded areas altogether is the best way to prevent the contraction of DTV. Individuals who regularly participate in outdoor activities can take effective precautionary measures, such as remaining in the center of cleared trails, covering as much skin as possible, and spraying appropriate chemicals on clothes and exposed skin, to avoid the bite of the blacklegged tick.
Caused by a bacterium found in animals like rabbits and rodents, tularemia is a potentially serious disease that occurs throughout the United States. Dog ticks, wood ticks, and Lone Star ticks serve as carriers of the disease.
Humans can become infected via the skin, eyes, mouth, throat, or lungs, and symptoms depend on which portal the bacteria pass through to enter the body. In addition to being spread by the bites of certain tick species, tularemia can be contracted by handling an infected animal or carcass, eating or drinking contaminated materials, or inhaling the bacteria directly. To date, there have been no reported instances of human-to-human transmission.
General symptoms of tularemia include fever, chills, diarrhea, joint pain, and progressive weakness. Other symptoms may also appear, depending on the way the disease entered the body of the patient. Tularemia symptoms first develop after three to five days, though some people experience the initial onset of symptoms as many as 14 days after exposure to the bacteria. Ulceroglandular tularemia, which occurs from the bite of an infected tick or by handling an infected animal, is the most common form of the disease and usually results in the development of a skin ulcer at the point of contact and the swelling of the lymph glands in either the armpit or groin area.
Other forms of tularemia include glandular, oculoglandular, and oropharyngeal. Glandular tularemia produces symptoms similar to the ulceroglandular variety, except for the development of the skin ulcer. Oculoglandular tularemia occurs when the disease enters the body through the eyes, while the oropharyngeal variety results from ingesting contaminated food or water. The most serious form of the disease is pneumonic tularemia, which occurs as a result of inhaling dusts or aerosols that contain the bacteria and includes symptoms like a cough, chest pain, and trouble breathing. If left untreated, the other forms of the disease can lead to pneumonic tularemia as the bacteria spreads to both the bloodstream and the lungs.
A rare disease, tularemia is difficult to diagnose and sometimes mistaken for more common illnesses. Blood tests help confirm diagnoses of tularemia, and doctors typically prescribe antibiotics to eliminate the disease. Treatment may last up to three weeks, depending on how quickly the disease was discovered. The elderly and patients with weakened immune systems may become prone to the more severe symptoms of tularemia, such as pneumonia.
Tick paralysis is the only tick-borne disease not caused by any type of infectious agent; instead, the disease results from exposure to a neurotoxin in the salivary glands of the tick. The most common species to transmit tick paralysis include the American dog tick and the Rocky Mountain wood tick, though the black-legged or deer tick has also been known to spread the disease.
While cases have also been documented in the Southeast and New England, tick paralysis occurs most frequently in the Western region of the country. The disease follows a seasonal pattern and is more prevalent in the summer months. Though not a common affliction, tick paralysis affects younger children and adult males more often than other demographics. The debilitating disease can also affect domesticated pets and tends to be more commonly found in dogs than cats.
Tick paralysis symptoms start to show within a week of tick attachment and first appear as ataxia, or the lack of voluntary control of muscle movement, characterized by an abnormal gait. Actual paralysis moves up the body from the feet and legs. Other symptoms may precede paralysis and frequently include numbness, lethargy and discomfort, and slowed reflexes. The development of a fever, while common in cases of other tick-borne illnesses, is rarely a symptom of tick paralysis.
In some cases, tick paralysis can become life threatening due to the way the paralyzing condition ascends to the upper body and affects the respiratory muscles. For dogs affected by the disease, symptoms of tick paralysis develop gradually and may include vomiting or regurgitation, high blood pressure, low muscle tone, complete or partial loss of movement, and excessive drooling.
No tests exist to diagnose tick paralysis, which is often confused with Guillain-Barre syndrome due to the rapid onset of muscle weakness and the similar effects of the diseases on the nervous system. Although ticks are known to hide in hard-to-reach places on the body, finding and identifying the offending parasite remains crucial to the treatment of tick paralysis. Once the tick is removed, most patients report marked improvement and recover quickly with proper treatment. Affected pets may require emergency veterinarian care to recover from the more severe symptoms of tick paralysis.
A tick-borne bacterial infection, ehrlichiosis affects the white blood cells of various mammals, including humans. The principle vector of the disease is the Lone Star tick, which utilizes various mammalian hosts like the white-tailed deer and the white-footed mouse. While most cases of ehrlichiosis originate in the American Southwest and California, the disease also occurs with some frequency in the Southeast and New England states. The time between April and September brings the greatest risk of contracting the disease, though avoidance is possible if proper precautionary measures are taken by people who live, work, or travel in areas with large tick populations.
While most patients remain asymptomatic and may not even remember the tick bite occurring, others develop a variety of symptoms indicative of a tick-borne illness. Indicators typically develop one to two weeks after being bitten by the infected tick. Common symptoms of ehrlichiosis include fever, headache, chills, muscle pain, conjunctivitis, and rash. The rash appears more commonly on children than adults and is generally not itchy. Ehrlichiosis symptoms vary according to the individual person and often show up in different combinations. The malady can be fatal if misdiagnosed or left untreated, as it causes difficulty breathing and bleeding disorders.
The best way to detect ehrlichiosis is through blood testing. Treatment usually comes in the form of antibiotics. Patients with compromised immunity due to cancer treatments, HIV infection, or organ transplants may react more severely to ehrlichiosis and could face long-term complications like renal or respiratory failure, myocarditis, or even death if proper treatment is not administered. To avoid contracting ehrlichiosis, take preventative measures in areas where ticks like to live, such as grassy fields, offbeat paths, and dense forests.
Also known as human granulocytic anaplasmosis (HGA) and formerly known as human granulocytic ehrlichiosis (HGE) until 2001, anaplasmosis is a bacterial infection spread by ticks. In the eastern part of the United States, the disease is transmitted by the bite of an infected black-legged tick. Commonly referred to as deer ticks, black-legged ticks live in wooded and grassy areas, which makes the likelihood of contracting anaplasmosis greater for individuals who regularly spend time in these types of settings. Geographically, anaplasmosis occurs most frequently in the Upper Midwest and Northeast regions of the country.
Infected deer ticks spread anaplasmosis by biting a host animal and causing the bacterium Anaplasma phagocytophilium to enter the bloodstream. The first symptoms usually appear within a week or two of the bite. Symptoms of anaplasmosis include fever, headache, chills, muscle aches, nausea or abdominal pain, cough, and general malaise. In rare instances, a rash may develop. Anaplasmosis symptoms vary depending on the person and typically dissipate after one to two weeks. In less than 1% of anaplasmosis cases, however, the infection results in fatality.
Most reported cases of anaplasmosis occur during the summer, peaking in June and July, when black-legged ticks are highly active. Statistically, anaplasmosis tends to affect men and people older than 40 most frequently. Individuals with compromised immune systems also remain at greater risk of contracting the tick-borne infection. Treating anaplasmosis usually involves prescription antibiotics. While a full recovery is sometimes possible without medical assistance, early treatment helps prevent more serious issues from arising as a result of the disease.
Babesiosis is a disease caused by microscopic parasites that infect the red blood cells of the victim. It is passed to humans primarily through the bite of the black-legged tick, otherwise known as the deer tick. The main host animal of the black-legged tick is the white-tailed deer, which are prevalent throughout many regions of the country. For those who live, work, or otherwise spend a great deal of time in grassy outdoor areas, the chance of coming into contact with black-legged ticks is heightened.
Transmitted mainly by deer tick nymphs, babeiosis is most common during the warmer months of the year when the nymphal stage of development tends to occur. The disease produces symptoms that range from mild to life-threatening, depending on the person affected. Symptoms usually show up within a week or two of being bitten, though the severity of the symptoms depends on mitigating factors. While most people experience flu-like signs such as fever, chills, headache, nausea, and fatigue, the elderly and those with weakened immune systems may face more serious effects, including jaundice, darkened urine, and possibly even hemolytic anemia.
In some cases, people with babesiosis may not feel any symptoms, let alone remember being bitten by a deer tick. Doctors must administer a specialized blood test to confirm suspected cases of the disease. For patients with previously existing health issues, complications may become severe enough to result in unstable blood pressure, disseminated intravascular coagulation (DIC), organ failure, and even death.
To reduce the chances of encountering a deer tick and contracting babesiosis, stick to cleared trails when walking outdoors, wear light-colored clothing, apply repellents to both skin and clothes, and minimize the amount of exposed skin by tucking pant legs inside shoes or boots. Perform tick checks upon returning from outdoor excursions, and remove any found ticks from clothing and pets before reentering the home.
Borrelia miyamotoi are spiral-shaped bacteria first identified in 1995 and distantly related to the bacteria that cause Lyme disease. Discovered in Japan, the disease has since been detected in two species of North American ticks: the black-legged tick, also known as the deer tick, and the western black-legged tick. While the first known cases of human infection occurred in Russia as recently as 2011, only three cases of B. miyamotoi have been confirmed in the United States to date.
Black-legged ticks occupy the Northeast and Upper Midwest, while western black-legged ticks live on the Pacific Coast. Residents of these areas should remain mindful of standard tick prevention tips in order to avoid B. miyamotoi and various other tick-borne diseases. Simple safety measures like adhering to clear trails in areas of tall grass, applying tick repellants before spending significant amounts of time outdoors, and thoroughly checking for adult ticks before coming back indoors can lead to the effective avoidance of tick bites.
Due to the relative rarity of Borrelia miyamotoi, the key signs and symptoms are not clearly defined. However, in documented cases of the disease, the majority of infected people experienced fever, headache, and muscle aches. Some uncommon but notable symptoms include erythema, migrans rash or bull’s-eye rash, arthritis, and facial palsy. Diagnosing the tick-borne disease involves a battery of tests called polymerase chain reaction tests (PCR), which detect the DNA of the bacterial organism. Blood tests may also be used to identify coinciding antibodies. All known cases of Borrelia miyamotoi have been successfully treated with a two-week course of doxycycline, an antibiotic also used to treat severe acne.
Southern Tick-Associated Rash Illness
Often mistaken for a symptom of Lyme disease, Southern Tick-Associated Rash Illness, or STARI, develops around the site of a Lone Star tick bite. Found throughout the eastern, southeastern, and south-central United States, the Lone Star tick has become more widely distributed over the past three decades and now holds a strong presence as far north as the southern parts of most New England states. Both humans and household pets, such as cats and dogs, serve as hosts for the parasite. The specific cause of the illness remains unknown.
STARI produces a rash that looks like an expanding bull’s-eye positioned around the site of a Lone Star tick bite. Irritated, red, and approximately three inches in diameter, the rash typically develops about a week after the initial encounter with the infected tick. Accompanying symptoms may include fatigue, headache, fever, and muscle pain. The saliva of Lone Star ticks is irritating on its own, so redness and discomfort around the site of a bite does not necessarily indicate a case of STARI. In lieu of diagnostic blood tests, doctors and healthcare providers must use the noticeable symptoms and geographic location of the patient and determine whether the victim was exposed to a Lone Star tick in order to make an accurate diagnosis.
Despite the lack of definitive knowledge about the disease, Southern Tick-Associated Rash Illness is easy to treat. The rash, as well as additional symptoms, clears up after a round of oral antibiotics. While STARI seems less problematic than other tick-borne illnesses, avoiding contact with the Lone Star tick should still be a priority for outdoor enthusiasts. Any time spent in grassy and wooded areas should be restricted to clear trails. Apply chemical repellants on skin and clothing before venturing outdoors, and check equipment, clothes, exposed skin, and pets for ticks before returning inside. When ticks become attached to clothing, drying the garments at high temperatures will eradicate the clinging parasites.
Other diseases include:
- Powassan Disease
From the LMZ
The University of Massachusetts Laboratory of Medical Zoology
(formerly www.tickdiseases.org or the “Tick-Borne Disease Network”)
The Laboratory of Medical Zoology (LMZ) is an academic research lab at the University of Massachusetts, Amherst. The focus of our research is on infectious diseases, with particular attention to those diseases with transmission cycles that involve other animal species. The general term for these diseases is “zoonoses.” Zoonoses come in many kinds and are as diverse as the animal and microbial kingdoms.
The study of infectious diseases traditionally is conducted by various kinds of biologists such medical entomologists, medical microbiologists, epidemiologists, etc.. We identify ourselves at the intersection of those disciplines, hence Medical Zoology, because we study animals (and microbes) of medical relevance, and don’t draw the line at any particular taxonomic group.
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