Tick-borne diseases, which afflict humans and other animals, are caused by infectious agents transmitted by

tick Ticks (order Ixodida) are parasitic arachnids that are part of the mite superorder Parasitiformes. Adult ticks are approximately 3 to 5 mm in length depending on age, sex, species, and "fullness". Ticks are external parasites, living ...

bites. They are caused by infection with a variety of

pathogen In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a g ...

s, including

rickettsia ''Rickettsia'' is a genus of nonmotile, gram-negative, nonspore-forming, highly pleomorphic bacteria that may occur in the forms of cocci (0.1 μm in diameter), bacilli (1–4 μm long), or threads (up to about 10 μm long). The term "ricke ...

and other types of

bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were am ...

virus A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Since Dmitri Ivanovsk ...

es, and

protozoa Protozoa (singular: protozoan or protozoon; alternative plural: protozoans) are a group of single-celled eukaryotes, either free-living or parasitic, that feed on organic matter such as other microorganisms or organic tissues and debris. Histo ...

. The economic impact of tick-borne diseases is considered to be substantial in humans, and tick-borne diseases are estimated to affect ~80 % of

cattle Cattle (''Bos taurus'') are large, domesticated, cloven-hooved, herbivores. They are a prominent modern member of the subfamily Bovinae and the most widespread species of the genus '' Bos''. Adult females are referred to as cows and adult ...

worldwide. 18 tick-borne pathogens have been identified in the United States according to the

Centers for Disease Control The Centers for Disease Control and Prevention (CDC) is the national public health agency of the United States. It is a United States federal agency, under the Department of Health and Human Services, and is headquartered in Atlanta, Georgi ...

and at least 27 are known globally. New tick-borne diseases have been discovered in the 21st century, due in part to the use of molecular assays and

next-generation sequencing Massive parallel sequencing or massively parallel sequencing is any of several high-throughput approaches to DNA sequencing using the concept of massively parallel processing; it is also called next-generation sequencing (NGS) or second-generation ...

. The occurrence of ticks and tick-borne illnesses in humans is increasing. Tick populations are spreading into new areas, in part due to climate change. Tick populations are also affected by changes in the populations of their hosts (e.g. deer, cattle, mice, lizards) and those hosts' predators (e.g. foxes). Diversity and availability of hosts and predators can be affected by

deforestation Deforestation or forest clearance is the removal of a forest or stand of trees from land that is then converted to non-forest use. Deforestation can involve conversion of forest land to farms, ranches, or urban use. The most concentrated ...

and habitat fragmentation. Because individual ticks can harbor more than one disease-causing agent, patients can be infected with more than one pathogen at the same time, compounding the difficulty in diagnosis and treatment. As the incidence of tick-borne illnesses increases and the geographic areas in which they are found expand, health workers increasingly must be able to distinguish the diverse, and often overlapping, clinical presentations of these diseases.

Prevention

Exposure

Ticks tend to be more active during warmer months, though this varies by geographic region and climate. Areas with woods, bushes, high grass, or leaf litter are likely to have more ticks. Those bitten commonly experience symptoms such as body aches,

fever Fever, also referred to as pyrexia, is defined as having a temperature above the normal range due to an increase in the body's temperature set point. There is not a single agreed-upon upper limit for normal temperature with sources using val ...

fatigue Fatigue describes a state of tiredness that does not resolve with rest or sleep. In general usage, fatigue is synonymous with extreme tiredness or exhaustion that normally follows prolonged physical or mental activity. When it does not resolve ...

joint pain Arthralgia (from Greek ''arthro-'', joint + ''-algos'', pain) literally means ''joint pain''. Specifically, arthralgia is a symptom of injury, infection, illness (in particular arthritis), or an allergic reaction to medication. According to MeSH, ...

, or

rash A rash is a change of the human skin which affects its color, appearance, or texture. A rash may be localized in one part of the body, or affect all the skin. Rashes may cause the skin to change color, itch, become warm, bumpy, chapped, dry, c ...

es. People can limit their exposure to tick bites by wearing light-colored clothing (including pants and long sleeves), using

insect repellent An insect repellent (also commonly called "bug spray") is a substance applied to skin, clothing, or other surfaces to discourage insects (and arthropods in general) from landing or climbing on that surface. Insect repellents help prevent and cont ...

with 20%–30% N,N-Diethyl-3-methylbenzamide (DEET), tucking their pants legs into their socks, checking for ticks frequently, and washing and drying their clothing in a hot dryer. According to the

World Health Organization The World Health Organization (WHO) is a specialized agency of the United Nations responsible for international public health. The WHO Constitution states its main objective as "the attainment by all peoples of the highest possible level o ...

, tick-to-animal transmission is difficult to prevent because animals do not show visible symptoms; the only effective prevention relies on killing ticks on the livestock production facility.

Tick removal

Ticks should be removed as soon as safely possible once discovered. They can be removed either by grasping tweezers as close to the mouth as possible and pulling without rotation; some companies market grooved tools that rotate the

hypostome In zoology, the hypostome can refer to structures in distinct animal groups: * Hypostome (trilobite), the ventral mouthpart plate in trilobites * Hypostome (tick), the barbed attachment structure associated with the mouthparts of parasitic arachni ...

to facilitate removal. Chemical methods to make the tick self-detach, or trying to pull the tick out with one’s fingers, are not efficient methods.

Diagnosis

In general, specific laboratory tests are not available for rapid diagnosis of tick-borne diseases. Due to their seriousness,

antibiotic An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention ...

treatment is often justified based on clinical presentation alone.

Assessing risk

For a person or pet to acquire a tick-borne disease requires that the individual gets bitten by a tick and that the tick feeds for a sufficient period of time. The feeding time required to transmit pathogens differs for different ticks and different pathogens. Transmission of the bacterium that causes

Lyme disease Lyme disease, also known as Lyme borreliosis, is a vector-borne disease caused by the '' Borrelia'' bacterium, which is spread by ticks in the genus '' Ixodes''. The most common sign of infection is an expanding red rash, known as erythema ...

is well understood to require a substantial feeding period. In general, soft ticks (

Argasidae The Argasidae are the family of soft ticks, one of the three families of ticks. The family contains 193 species, although the composition of the genera is less certain, and more study is needed before the genera can become stable. The currently ...

) transmit pathogens within minutes of attachment because they feed more frequently, whereas hard ticks (

Ixodidae The Ixodidae are the family of hard ticks or scale ticks, one of the three families of ticks, consisting of over 700 species. They are known as 'hard ticks' because they have a scutum or hard shield, which the other major family of ticks, the 'sof ...

) take hours or days, but the latter are more common and harder to remove. For an individual to acquire infection, the feeding tick must also be infected. Not all ticks are infected. In most places in the US, 30-50% of deer ticks will be infected with ''

Borrelia burgdorferi ''Borrelia burgdorferi'' is a bacterial species of the spirochete class in the genus '' Borrelia'', and is one of the causative agents of Lyme disease in humans. Along with a few similar genospecies, some of which also cause Lyme disease, it mak ...

'' (the agent of Lyme disease). Other pathogens are much more rare. Ticks can be tested for infection using a highly specific and sensitive qPCR procedure. Several commercial labs provide this service to individuals for a fee. The Laboratory of Medical Zoology (LMZ), a nonprofit lab at the

University of Massachusetts The University of Massachusetts is the five-campus public university system and the only public research system in the Commonwealth of Massachusetts. The university system includes five campuses (Amherst, Boston, Dartmouth, Lowell, and a medical ...

, provides a comprehensive TickReport for a variety of human pathogens and makes the data available to the public. Those wishing to know the incidence of tick-borne diseases in their town or state can search the LMZ surveillance database.

Examples

Major tick-borne diseases include:

Bacterial

or borreliosis **Organism: '' Borrelia burgdorferi sensu lato'' (bacterium) **Vector: at least 15 species of ticks in the genus ''Ixodes'', including deer tick (''Ixodes scapularis'' (=''I. dammini''), ''I. pacificus'', ''I. ricinus'' (Europe), ''I. persulcatus'' (Asia)) **Endemic to: The Americas and Eurasia **Symptoms:

Fever Fever, also referred to as pyrexia, is defined as having a temperature above the normal range due to an increase in the body's temperature set point. There is not a single agreed-upon upper limit for normal temperature with sources using val ...

arthritis Arthritis is a term often used to mean any disorder that affects joints. Symptoms generally include joint pain and stiffness. Other symptoms may include redness, warmth, swelling, and decreased range of motion of the affected joints. In som ...

, neuroborreliosis,

erythema migrans Erythema migrans or erythema chronicum migrans is an expanding rash often seen in the early stage of Lyme disease, and can also (but less commonly) be caused by southern tick-associated rash illness (STARI). Page last reviewed: October 22, 2015 ...

, cranial nerve palsy, carditis, fatigue, and influenza-like illness **Treatment: Antibiotics -

amoxicillin Amoxicillin is an antibiotic medication used to treat a number of bacterial infections. These include middle ear infection, strep throat, pneumonia, skin infections, and urinary tract infections among others. It is taken by mouth, or less c ...

in pregnant adults and children), (

doxycycline Doxycycline is a broad-spectrum tetracycline class antibiotic used in the treatment of infections caused by bacteria and certain parasites. It is used to treat bacterial pneumonia, acne, chlamydia infections, Lyme disease, cholera, typhus ...

in other adults *

Relapsing fever Relapsing fever is a vector-borne disease caused by infection with certain bacteria in the genus '' Borrelia'', which is transmitted through the bites of lice or soft-bodied ticks (genus ''Ornithodoros''). Signs and symptoms Most people who ar ...

(tick-borne relapsing fever, different from Lyme disease due to different ''Borrelia'' species and ticks) **Organisms: ''

Borrelia ''Borrelia'' is a genus of bacteria of the spirochete phylum. Several species cause Lyme disease, also called Lyme borreliosis, a zoonotic, vector-borne disease transmitted by ticks. Other species of ''Borrelia'' cause relapsing fever, and are t ...

'' species such as ''B. hermsii,'' ''B. parkeri'', ''B. duttoni'', ''B. miyamotoi'' **Vector: ''

Ornithodoros ''Ornithodoros'' is a genus in the soft-bodied tick family, Argasidae. Physiology The opening between the midgut and hindgut has been lost, making the ticks unable to pass digestive waste products out of their bodies. Taxonomy The Linnean name ...

'' species **Regions : Primarily in Africa, Spain, Saudi Arabia, Asia in and certain areas of Canada and the western United States **Symptoms: Relapsing fever typically presents as recurring high fevers, flu-like symptoms, headaches, and muscular pain, with less common symptoms including

rigors Chills is a feeling of coldness occurring during a high fever, but sometimes is also a common symptom which occurs alone in specific people. It occurs during fever due to the release of cytokines and prostaglandins as part of the inflammatory r ...

, joint pain, altered mentation, cough, sore throat, painful urination, and rash **Treatment: Antibiotics are the treatment for relapsing fever, with doxycycline, tetracycline, or erythromycin being the treatment of choice. *

Typhus Typhus, also known as typhus fever, is a group of infectious diseases that include epidemic typhus, scrub typhus, and murine typhus. Common symptoms include fever, headache, and a rash. Typically these begin one to two weeks after exposure. ...

Several diseases caused by ''Rickettsia'' bacteria (below) *

Rocky Mountain spotted fever Rocky Mountain spotted fever (RMSF) is a bacterial disease spread by ticks. It typically begins with a fever and headache, which is followed a few days later with the development of a rash. The rash is generally made up of small spots of bleedin ...

**Organism: ''Rickettsia rickettsii'' **Vector: Wood tick (''

Dermacentor variabilis ''Dermacentor variabilis'', also known as the American dog tick or wood tick, is a species of tick that is known to carry bacteria responsible for several diseases in humans, including Rocky Mountain spotted fever and tularemia (''Francisella tul ...

''), ''D. andersoni'' **Region (US): East, Southwest **Vector: ''

Amblyomma cajennense ''Amblyomma cajennense'' or Cayenne tick is a species of tick found in a range from the southern part of the United States to northern Argentina, through Central America and some of the Caribbean. As a consequence the species has adapted to a wi ...

'' **Region (Brazil):

São Paulo São Paulo (, ; Portuguese for ' Saint Paul') is the most populous city in Brazil, and is the capital of the state of São Paulo, the most populous and wealthiest Brazilian state, located in the country's Southeast Region. Listed by the GaW ...

Rio de Janeiro Rio de Janeiro ( , , ; literally 'River of January'), or simply Rio, is the capital of the state of the same name, Brazil's third-most populous state, and the second-most populous city in Brazil, after São Paulo. Listed by the GaWC as a b ...

Minas Gerais Minas Gerais () is a state in Southeastern Brazil. It ranks as the second most populous, the third by gross domestic product (GDP), and the fourth largest by area in the country. The state's capital and largest city, Belo Horizonte (literall ...

. **Symptoms:Fever, headache,

altered mental status An altered level of consciousness is any measure of arousal other than normal. Level of consciousness (LOC) is a measurement of a person's arousability and responsiveness to stimuli from the environment. A mildly depressed level of consciousn ...

myalgia Myalgia (also called muscle pain and muscle ache in layman's terms) is the medical term for muscle pain. Myalgia is a symptom of many diseases. The most common cause of acute myalgia is the overuse of a muscle or group of muscles; another li ...

, and

**Treatment:

Antibiotic An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention ...

therapy, typically consisting of doxycycline or tetracycline * Helvetica spotted fever **Organism: ''Rickettsia helvetica'' **Region(''R. helvetica''): Confirmed common in ticks in Sweden, Switzerland, France, and Laos **Vector/region(s)#1: ''

Ixodes ricinus ''Ixodes ricinus'', the castor bean tick, is a chiefly European species of hard-bodied tick. It may reach a length of when engorged with a blood meal, and can transmit both bacterial and viral pathogens such as the causative agents of Lyme disea ...

'' is the main European vector. **Symptoms: Most often small red spots, other symptoms are fever, muscle pain, headache and respiratory problems **Treatment: Broad-spectrum

therapy is needed, phenoxymethylpenicillin likely is sufficient. *

Human granulocytic anaplasmosis Human granulocytic anaplasmosis (HGA) is a tick-borne, infectious disease caused by ''Anaplasma phagocytophilum'', an obligate intracellular bacterium that is typically transmitted to humans by ticks of the '' Ixodes ricinus'' species complex, i ...

(formerly human granulocytic ehrlichiosis or HGE) **Organism: ''

Anaplasma phagocytophilum ''Anaplasma phagocytophilum'' (formerly ''Ehrlichia phagocytophilum'') is a Gram-negative bacterium that is unusual in its tropism to neutrophils. It causes anaplasmosis in sheep and cattle, also known as tick-borne fever and pasture fever, and ...

'' (formerly ''Ehrlichia phagocytophilum'' or ''Ehrlichia equi'') **Vector: Lone star tick (''Amblyomma americanum''), ''I. scapularis'' **Region (US): South Atlantic, South-central *''

Bartonella ''Bartonella'' is a genus of Gram-negative bacteria. It is the only genus in the family Bartonellaceae. Facultative intracellular parasites, ''Bartonella'' species can infect healthy people, but are considered especially important as opportunis ...

'': ''Bartonella ''transmission rates to humans via tick bite are not well established but Bartonella is common in ticks. For example: 4.76% of 2100 ticks tested in a study in Germany *

Tularemia Tularemia, also known as rabbit fever, is an infectious disease caused by the bacterium ''Francisella tularensis''. Symptoms may include fever, skin ulcers, and enlarged lymph nodes. Occasionally, a form that results in pneumonia or a throat infe ...

**Organism: ''Francisella tularensis'', ''A. americanum'' **Vector: '' D. variabilis'', ''D. andersoni'' **Region (US): Southeast, South-central, West, widespread

Viral

Tick-borne meningoencephalitis Tick-borne encephalitis (TBE) is a viral infectious disease involving the central nervous system. The disease most often manifests as meningitis, encephalitis or meningoencephalitis. Myelitis and spinal paralysis also occurs. In about one third ...

**Organism: TBEV (FSME) virus, a flavivirus from family ''

Flaviviridae ''Flaviviridae'' is a family of enveloped positive-strand RNA viruses which mainly infect mammals and birds. They are primarily spread through arthropod vectors (mainly ticks and mosquitoes). The family gets its name from the yellow fever viru ...

'' **Vector: deer tick ('' Ixodes scapularis''), ''

'' (Europe), '' Ixodes persulcatus'' (Russia + Asia)) **Endemic to: Europe and northern Asia *

Powassan virus ''Powassan virus (POWV)'' is a ''Flavivirus'' transmitted by ticks, found in North America and in the Russian Far East. It is named after the town of Powassan, Ontario, where it was identified in a young boy who eventually died from it. It can c ...

/deer tick virus ** Organism: Powassan virus (POWV), a flavivirus from family ''

''. Lineage 2 POWV is also known as deer tick virus (DTV) ** Vector: '' Ixodes cookei'', '' Ix. scapularis'', ''Ix. marxi'', ''Ix. spinipalpus''m, '' Dermacentor andersoni'', and '' D. variabilis'' ** Endemic to: North America and eastern Russia *

Colorado tick fever Colorado tick fever (CTF) is a viral infection (Coltivirus) transmitted from the bite of an infected Rocky Mountain wood tick ('' Dermacentor andersoni''). It should not be confused with the bacterial tick-borne infection, Rocky Mountain spotted f ...

**Organism: Colorado tick fever virus (CTF), a

coltivirus Coltivirus is a genus of viruses (belonging to the ''Reoviridae'' family) that infects vertebrates and invertebrates. It includes the causative agent of Colorado tick fever. Colorado tick fever virus can cause a fever, chills, headache, photopho ...

from the ''

Reoviridae ''Reoviridae'' is a family of double-stranded RNA viruses. Member viruses have a wide host range, including vertebrates, invertebrates, plants, protists and fungi. They lack lipid envelopes and package their segmented genome within multi-layere ...

'' **Vector: '' Dermacentor andersoni'' **Region: US (West) * Crimean-Congo hemorrhagic fever **Organism: CCHF virus, a nairovirus, from the ''

Bunyaviridae ''Bunyavirales'' is an order of segmented negative-strand RNA viruses with mainly tripartite genomes. Member viruses infect arthropods, plants, protozoans, and vertebrates. It is the only order in the class ''Ellioviricetes''. The name ''Bunyav ...

'' **Vector: '' Hyalomma marginatum'', '' Rhipicephalus bursa'' **Region: Southern part of Asia, Northern Africa, Southern Europe *Severe febrile illness **Organism: Heartland virus, a

phlebovirus ''Phlebovirus'' is one of twenty genera of the family ''Phenuiviridae'' in the order ''Bunyavirales''. The genus contains 66 species. It derives its name from Phlebotominae, the vectors of member species '' Naples phlebovirus'', which is said to ...

, from the ''

'' **Vector: Lone star tick (''Amblyomma americanum'') **Region: Missouri and Tennessee, United States *Severe febrile illness, headaches, coma in 1/3 patients **Organism: tentatively Alongshan virus, jingmenvirus group in the flavivirus family **Vector: tick (likely '' Ixodes persulcatus'', ''

''), mosquitoes **Region: Inner Mongolia but potentially more widespread

Protozoan

Babesiosis Babesiosis or piroplasmosis is a malaria-like parasitic disease caused by infection with a eukaryotic parasite in the order Piroplasmida, typically a ''Babesia'' or ''Theileria'', in the phylum Apicomplexa. Human babesiosis transmission via tic ...

**Organism: '' Babesia microti'', ''

Theileria equi ''Theileria'' is a genus of parasites that belongs to the phylum Apicomplexa, and is closely related to ''Plasmodium''. Two ''Theileria'' species, ''T. annulata'' and ''T. parva'', are important cattle parasites. ''T. annulata'' causes tropical ...

'' **Vector: '' Ixodes scapularis'' (deer tick), '' I. pacificus'' (western black-legged tick) **Region (US): Northeast, West Coast *

Cytauxzoonosis ''Cytauxzoon felis'' is a protozoal organism transmitted to domestic cats by tick bites, and whose natural reservoir host is the bobcat. ''C. felis'' has been found in other wild felid species such as the cougar, as well as a white tiger in capt ...

**Organism: ''Cytauxzoon felis'' **Vector: ''

Amblyomma americanum ''Amblyomma americanum'', also known as the lone star tick, the northeastern water tick, or the turkey tick, or the "Cricker Tick", is a type of tick indigenous to much of the eastern United States and Mexico, that bites painlessly and commonly ...

'' (Lone star tick) **Region (US): South, Southeast

Toxin

* Tick paralysis **Cause: Toxin **Vector (US): '' Dermacentor andersoni'' (Rocky Mountain wood tick), '' D. variabilis'' (American dog tick or wood tick) **Region (US): ''D. andersoni'': East, ''D. variabilis'': East, West coast **Vector (Australia): '' Ixodes holocyclus'' (Australian paralysis tick) **Region (Australia): East

Allergies

Alpha-gal allergy Alpha-gal allergy — or mammalian meat allergy (MMA) — is a type of meat allergy characterized by a delayed onset of symptoms (3–8 hours) after ingesting mammalian meat and resulting from past exposure to tick bites. It was first reported in ...

- Alpha-gal syndrome is likely caused by a hypersensitivity reaction to the Alpha-gal (Galactose-alpha-1,3-galactose) sugar molecule introduced by ticks while feeding on a human host. The immune reaction can leave people with an allergy to red meat and other mammalian derived products.Crispell, Gary; Commins, Scott P.; Archer-Hartman, Stephanie A.; Choudhary, Shailesh; Dharmarajan, Guha; Azadi, Parastoo; Karim, Shahid (17 May 2019). "Discovery of Alpha-Gal-Containing Antigens in North American Tick Species Believed to Induce Red Meat Allergy". Frontiers in Immunology. 10: 1056. https://doi.org/10.3389/fimmu.2019.01056. PMC 6533943. PMID 31156631

References

External links

Tick-Borne Diseases: Recommendations for Workers and Employers
��National Institute for Occupational Safety and Health
Tickborne Diseases
��National Center for Infectious Diseases (CDC)

��Massachusetts Department of Public Health

��3D animation of Deer or Blacklegged Tick from US Army site
Parasitic Insects, Mites and Ticks: Genera of Medical and Veterinary Importance
Wikibooks {{DEFAULTSORT:Tick-Borne Disease