Tick-Borne Diseases

The District provides guidelines for how to prevent tick-borne diseases.

Reduce your chances of contracting tick-borne diseases by removing a tick promptly.

Babesiosis

Bebesiosis illustration

Babesiosis is an infection caused by the malaria-like protozoan, Babesia microti. The first case was reported in 1969 from Nantucket Island, MA. Since then, babesiosis has emerged as a health threat in the United States, with increasing reports of babesiosis symptoms and some deaths in areas where the risk of infection was not previously recognized. Like malaria, the protozoan inhabits red blood cells and can result in anemia-causing fatigue and poor exercise tolerance.

Infections range from asymptomatic to mild in the young. It can be severe and even life-threatening in patients without spleens, immune-compromised patients, and older patients with pre-existing medical conditions. Antibiotics are effective in treating the infection and fewer complications occur with earlier treatment.

Where Is It Found?

Babesiosis occurs mainly in coastal areas in the northeastern United States, especially the offshore islands of New York and Massachusetts. Cases have also been reported in Wisconsin, California, Georgia, and in some European countries.

How Does It Spread?

Babesiosis is most commonly spread to people by the bite of a tick infected with the Babesia parasite. Babesiosis is spread by deer ticks, which are carried mainly by deer, meadow voles, and mice. Deer ticks also spread Lyme disease. People can be infected with both babesiosis and Lyme disease at the same time. People can also get babesiosis from a contaminated blood transfusion.

What Are the Symptoms?

The parasite attacks the red blood cells. Symptoms, if any, begin with tiredness, loss of appetite, and a general ill feeling. As the infection progresses, these symptoms are followed by fever, drenching sweats, muscle aches, and headache. The symptoms can last from several days to several months.

When Do Symptoms Occur?

It can take from 1 to 12 months for the first symptoms to appear, but less time for persons with weakened immune systems. Most cases occur during spring, summer, and fall.

How Is It Diagnosed?

Laboratory diagnosis is based on identifying the parasite in red blood cells.

tick on branch

Who Is at Risk?

Anyone can get babesiosis, but some people are at increased risk for severe disease:

  • Elderly persons
  • Persons with weakened immune systems
  • Persons whose spleens have been removed

Resulting Complications?

Complications include very low blood pressure, liver problems, severe hemolytic anemia (a breakdown of red blood cells), and kidney failure. Complications and death are most common in persons whose spleens have been removed. Other people usually have a milder illness and often get better on their own.

How Is It Treated?

A combination of anti-parasite medicines can be effective in treating babesiosis.

Is It Common?

It is not known how common babesiosis is in the United States. Most people have no symptoms, and those who do are usually older persons and people who are already sick with other conditions.

The District provides guidelines for how to prevent tick-borne diseases.

Ehrlichiosis

tick on skin

Ehrlichiosis is the general name used to describe several bacterial diseases that affect animals and humans. These diseases are caused by the organisms in the genus Ehrlichia.

Worldwide, there are currently four ehrlichial species that are known to cause disease in humans. Human ehrlichiosis due to Ehrlichia chaffeensis was first described in 1987. The disease occurs primarily in the southeastern and south central regions of the country and is primarily transmitted by the lone star tick, Amblyomma americanum.

Human granulocytic ehrlichiosis (HGE) represents the second recognized ehrlichial infection of humans in the United States, and was first described in 1994. The name for the species that causes HGE has not been formally proposed, but this species is closely related or identical to the veterinary pathogens Ehrlichia equi and Ehrlichia phagocytophila. HGE is transmitted by the blacklegged tick (Ixodes scapularis) and the western blacklegged tick (Ixodes pacificus) in the United States.

Ehrlichia ewingii is the most recently recognized human pathogen. Disease caused by E. ewingii has been limited to a few patients in Missouri, Oklahoma, and Tennessee, most of whom have had underlying immunosuppression. The full extent of the geographic range of this species, its vectors, and its role in human disease is currently under investigation.

Where Is It Found?

Most cases of ehrlichiosis are reported within the geographic distribution of the vector ticks. Occasionally, cases are reported from areas outside the distribution of the tick vector. In most instances, these cases have involved persons who traveled to areas where the diseases are endemic, and who had been bitten by an infected tick and developed symptoms after returning home. Therefore, if you traveled to an ehrlichiosis-endemic area 2 weeks prior to becoming ill, you should tell your doctor where you traveled.

How Does It Spread?

Ehrlichiae are transmitted by the bite of an infected tick. The lone star tick (Amblyomma americanum), the blacklegged tick (Ixodes scapularis), and the western blacklegged tick (Ixodes pacificus) are known vectors of ehrlichiosis in the United States. Ixodes ricinus is the primary vector in Europe.

What Are the Symptoms?

The symptoms of ehrlichiosis may resemble symptoms of various other infectious and non- infectious diseases. These clinical features generally include fever, headache, fatigue, and muscle aches. Other signs and symptoms may include nausea, vomiting, diarrhea, cough, joint pains, confusion, and occasionally rash.

When Do Symptoms Occur?

Symptoms typically appear after an incubation period of 5-10 days following the tick bite. It is possible that many individuals who become infected with ehrlichiae do not become ill or they develop only very mild symptoms.

How Is It Diagnosed?

A diagnosis of ehrlichiosis is based on a combination of clinical signs and symptoms and confirmatory laboratory tests. Your doctor can send your blood sample to a reference laboratory for testing. However, the availability of the different types of laboratory tests varies considerably. Other laboratory findings indicative of ehrlichiosis include low white blood cell count, low platelet count, and elevated liver enzymes.

How Is It Treated?

Ehrlichiosis is treated with a tetracycline antibiotic, usually doxycycline.

Can I Get It More Than Once?

Very little is known about immunity to ehrlichial infections. Although it has been proposed that infection with ehrlichiae confers long-term protection against reinfection, there have been occasional reports of laboratory-confirmed reinfection. Short-term protection has been described in animals infected with some Ehrlichia species and this protection wanes after about 1 year. Clearly, more studies are needed to determine the extent and duration of protection against reinfection in humans.

The District provides guidelines for how to prevent tick-borne diseases.

Rocky Mountain Spotted Fever

rocky mountains

Rocky Mountain Spotted Fever (RMSF) is the most severe tick-borne rickettsial illness in the United States. This disease is caused by infection with the bacterial organism Rickettsia rickettsii.

It was first recognized as a disease in the 1890’s. This disease is so named because it was discovered in the Rocky Mountains and infected persons had a rash with red-purple-black spots.

Where Is It Found?

RMSF is a seasonal disease and occurs throughout the United States during the months of April through September. Over half of the cases occur in the south-Atlantic region of the United States (Delaware, Maryland, Washington D.C., Virginia, West Virginia, North Carolina, South Carolina, Georgia, and Florida). The highest incidence rates have been found in North Carolina and Oklahoma. Although this disease was reported most frequently in the Rocky Mountain area early after its discovery, relatively few cases are reported from that area today.

How Does It Spread?

The organism that causes RMSF is transmitted by the bite of an infected tick. The American Dog Tick (Dermacentor variabilis) and Rocky Mountain Wood Tick (Dermacentor andersoni) are the primary vectors of Rocky Mountain Spotted Fever bacteria in the United States. Less commonly, infections may occur following exposure to crushed tick tissues, fluids, or tick feces.

What Are the Symptoms?

Initial symptoms may include fever, nausea, vomiting, muscle pain, lack of appetite and severe headache. Later signs and symptoms include rash, abdominal pain, joint pain, and diarrhea. Three important components of the clinical presentation are fever, rash, and a previous tick bite, although one or more of these components may not be present when the patient is first seen for medical care. RMSF can be a severe illness, and the majority of patients are hospitalized.

When Do Symptoms Occur?

Patients infected with R. rickettsii usually visit a physician in their first week of illness, following an incubation period of about 5-10 days after a tick bite. The early clinical presentation of RMSF is often nonspecific and may resemble many other infectious and non-infectious diseases.

How Is It Diagnosed?

A diagnosis of RMSF is based on a combination of clinical signs and symptoms and specialized confirmatory laboratory tests. Other common laboratory findings suggestive of RMSF include thrombocytopenia, hyponatremia, and elevated liver enzyme levels.

How Is It Treated?

RMSF is best treated by using a tetracycline antibiotic, usually doxycycline. This medication should be given in doses of 100 mg every 12 hours for adults or 4 mg/kg body weight per day in two divided doses for children under 45 kg (100 lbs). Patients are treated for at least 3 days after the fever subsides and until there is unequivocal evidence of clinical improvement. Standard duration of treatment is 5 to 10 days.

Can I Get It More Than Once?

Infection with R. rickettsii is thought to provide long lasting immunity against reinfection. However, prior illness with RMSF should not deter persons from practicing good tick-preventive measures or visiting a physician if signs and symptoms consistent with RMSF occur, especially following a tick bite.

The District provides guidelines for how to prevent tick-borne diseases.

Tularemia

rabbit

First described in Japan in 1837, tularemia is an infectious disease caused by the gram-negative pleomorphic bacterium, Francisella tularensis.

The disease name relates to the description in 1911 of a plague like illness in ground squirrels in Tulare County, CA and the subsequent work performed by Dr. Edward Francis. Tularemia is sometimes called rabbit fever.

F. tularensis is found worldwide in over 100 species of wild animals, birds, and insects. It produces an acute febrile illness in humans. The route of transmission and factors relating to the host and the organism influences presentation.

Where Is It Found?

A few hundred cases of tularemia are reported annually in the U.S. The majority of cases are likely unreported or misdiagnosed. While sporadic cases occur in all states, those with highest prevalence are Arkansas, Illinois, Missouri, Texas, Oklahoma, Utah, Virginia, and Tennessee. Frequency of tularemia has dropped markedly over the last 50 years, shifting from a winter disease (usually from rabbits) to a summer disease (more likely from ticks). Tularemia is found worldwide, but incidence is unknown.

How Does It Spread?

Many routes of human exposure to the tularemia germ are known to exist. The common routes include: inoculation of the skin or mucous membranes with blood or tissue while handling infected animals; contact with fluids from infected flies or ticks; or handling or eating insufficiently cooked rabbit meat. Less common means of spread are: drinking contaminated water; inhaling dust from contaminated soil; or handling contaminated pelts or paws of animals.

What Are the Symptoms?

Tularemia is usually recognized by the presence of a lesion and swollen glands. Ingestion of the organism may produce a throat infection, intestinal pain, diarrhea and vomiting. Inhalation of the organism may produce a fever alone or combined with a pneumonia-like illness.

When Do Symptoms Occur?

Symptoms generally appear between 2 and 10 days, but usually after 3 days.

How Is It Treated?

Certain antibiotics such as streptomycin are effective in treating tularemia. Others such as gentamicin and tobramycin have also been reported to be effective.

Can I Get It More Than Once?

Long-term immunity will follow recovery from tularemia, however, reinfection has been reported.

Who Is at Risk?

Hunters or other people who spend a great deal of time out of doors are at a greater risk of exposure to tularemia than people with other occupational or recreational interests.

Preventative Measures?

Rubber gloves should be worn when skinning or handling animals, especially rabbits. Wild rabbit and rodent meat should be cooked thoroughly before eating. Avoid bites of flies, mosquitoes and ticks and avoid drinking, bathing, swimming or working in untreated water.

The District provides guidelines for how to prevent tick-borne diseases.

Bartonella

Bartonella bacteria illustration

The genus Bartonella, a group of small, weakly-staining, gram-negative bacteria, includes two species currently of human medical importance in the United States.

These are B. henselae, which can cause Cat Scratch Disease (Fever), and B. quintana, which can cause Trench Fever.

cat scratches on hand

What Is Cat Scratch Disease?

Cat Scratch Disease is an infection caused by Bartonella henselae, characterized by regional lymphadenitis after a papule at the site of a cat scratch or tick bite. The domestic cat is a major reservoir for B. henselae. The prevalence of B. henselae antibodies in cats in the USA is 14% to 50%. In one study, 41% of pet cats had bacteremia, although all were asymptomatic. Most of the implicated felines are healthy. The cat flea may be an additional vector.

What Is Trench Fever?

Trench Fever is a bacterial infection recognized in soldiers in World War I has been reported uncommonly and sporadically around the world, including the United States. B. quintana rarely causes endocarditis in homeless, urban alcoholic men and bacillary angiomatosis, bacteremia, and other disseminated infections in AIDS patients. In patients with normal immune systems, trench fever caused by B. quintana presents as prolonged or recurrent fevers with a prolonged period of bacteremia, but with a low fatality rate. Body lice are a known vector for this disease.

How Is It Spread?

There is now evidence that ticks may be a significant transmitter of the Bartonella infection to humans. A study in California showed that a minimum of 2.3% of a pool of 1253 Ixodes pacificus ticks tested positive for Bartonella. Additionally, it appears that the Dermacentor species of ticks are also capable of transmitting the Bartonella bacteria.

What Are the Symptoms?

Early symptoms of Bartonella include a red, crusted, elevated skin lesion where the bacteria enters its host (which can mimic the Lyme disease enlarging rash), followed by flu-like symptoms of fever, muscle and joint aches/pains, nausea, vomiting, and chills. Also, enlargement of the lymph nodes around the ears is often present. More serious symptoms include encephalitis, which can result in headaches, dementia, seizures, coma, inflammation of the heart, abdominal pain, bone lesions, and loss of vision. Studies also indicate that some Lyme disease patients are also infected with Bartonella. Treatment with multiple antibiotics is becoming more common in these situations.

Who Is at Risk?

Disseminated B. henselae and B. quintana infections may cause several different pathologic entities in immunocompromised patients, most often those with AIDS. The most common manifestation is bacillary angiomatosis, characterized by protuberant, reddish, berry-like lesions on the skin, often surrounded by a collar of scale.

Q Fever

Q fever illustration

Q fever is a zoonotic disease caused by Coxiella burnetii, a species of bacteria that is distributed globally. In 1999, Q fever became a notifiable disease in the United States but reporting is not required in many other countries.

Because the disease is underreported, scientists cannot reliably assess how many cases of Q fever have actually occurred worldwide. Many human infections are inapparent.

Where Is It Found?

Cattle, sheep, and goats are the primary reservoirs of C. burnetii. Infection has been noted in a wide variety of other animals, including other breeds of livestock and in domesticated pets. Coxiella burnetii does not usually cause clinical disease in these animals, although abortion in goats and sheep has been linked to C. burnetii infection. 

Organisms are excreted in milk, urine, and feces of infected animals. Most importantly, during birthing the organisms are shed in high numbers within the amniotic fluids and the placenta. The organisms are resistant to heat, drying, and many common disinfectants. These features enable the bacteria to survive for long periods in the environment.

How Is It Spread?

Infection of humans usually occurs by inhalation of these organisms from air that contains airborne barnyard dust contaminated by dried placental material, birth fluids, and excreta of infected herd animals. Humans are often very susceptible to the disease, and very few organisms may be required to cause infection.

Ingestion of contaminated milk, followed by regurgitation and inspiration of the contaminated food, is a less common mode of transmission.

Other modes of transmission to humans, including tick bites and human to human transmission, are rare.

What Are the Symptoms?

Only about one-half of all people infected with C. burnetii show signs of clinical illness. Most acute cases of Q fever begin with sudden onset of one or more of the following: high fevers (up to 104-105° F), severe headache, general malaise, myalgia, confusion, sore throat, chills, sweats, non- productive cough, nausea, vomiting, diarrhea, abdominal pain, and chest pain.

Fever usually lasts for 1 to 2 weeks. Weight loss can occur and persist for some time. Thirty to fifty percent of patients with a symptomatic infection will develop pneumonia. Additionally, a majority of patients have abnormal results on liver function tests and some will develop hepatitis.

In general, most patients will recover to good health within several months without any treatment. Only 1%-2% of people with acute Q fever die of the disease.

Can It Be Chronic?

Chronic Q fever, characterized by infection that persists for more than 6 months, is uncommon but is a much more serious disease. Patients who have had acute Q fever may develop the chronic form as soon as 1 year or as long as 20 years after initial infection.

A serious complication of chronic Q fever is endocarditis, generally involving the aortic heart valves, less commonly the mitral valve. Most patients who develop chronic Q fever have pre-existing valvular heart disease or have a history of vascular graft. Transplant recipients, patients with cancer, and those with chronic kidney disease are also at risk of developing chronic Q fever. As many as 65% of persons with chronic Q fever may die of the disease.

The incubation period for Q fever varies depending on the number of organisms that initially infect the patient. Infection with greater numbers of organisms will result in shorter incubation periods. Most patients become ill within 2-3 weeks after exposure. Those who recover fully from infection may possess lifelong immunity against re-infection.

How Is It Treated?

A vaccine for Q fever has been developed and has successfully protected humans in occupational settings in Australia. However, this vaccine is not commercially available in the United States.

Persons wishing to be vaccinated should first have a skin test to determine a history of previous exposure. Individuals who have previously been exposed to C. burnetii should not receive the vaccine because severe reactions, localized to the area of the injected vaccine, may occur.

A vaccine for use in animals has also been developed, but it is not available in the United States.

Preventative Measures?

In the United States, Q fever outbreaks have resulted mainly from occupational exposure involving veterinarians, meat processing plant workers, sheep and dairy workers, livestock farmers, and researchers at facilities housing sheep. Prevention and control efforts should be directed primarily toward these groups and environments.

The District provides guidelines for how to prevent tick-borne diseases.