Tick-borne diseases, which afflict humans and other animals, are caused by infectious agents transmitted by tick bites. They are caused by infection with a variety of pathogens, including rickettsia and other types of bacteria, viruses, 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 worldwide. 18 tick-borne pathogens have been identified in the United States according to the Centers for Disease Control 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. 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 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,

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

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 is well understood to require a substantial feeding period. In general, soft ticks ( Argasidae) transmit pathogens within minutes of attachment because they feed more frequently, whereas hard ticks ( Ixodidae) 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'' (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, 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

* Lyme disease 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,

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

in other adults * Relapsing fever (tick-borne relapsing fever, different from Lyme disease due to different ''Borrelia'' species and ticks) **Organisms: '' Borrelia'' species such as ''B. hermsii,'' ''B. parkeri'', ''B. duttoni'', ''B. miyamotoi'' **Vector: '' Ornithodoros'' 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, 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 Several diseases caused by ''Rickettsia'' bacteria (below) * Rocky Mountain spotted fever **Organism: ''Rickettsia rickettsii'' **Vector: Wood tick ('' Dermacentor variabilis''), ''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, Rio de Janeiro, Minas Gerais. **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 consciousne ...

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 likel ...

, and rash **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 of ...

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'' 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 (formerly human granulocytic ehrlichiosis or HGE) **Organism: '' Anaplasma phagocytophilum'' (formerly ''Ehrlichia phagocytophilum'' or ''Ehrlichia equi'') **Vector: Lone star tick (''Amblyomma americanum''), ''I. scapularis'' **Region (US): South Atlantic, South-central *'' Bartonella'': ''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 **Organism: ''Francisella tularensis'', ''A. americanum'' **Vector: '' D. variabilis'', ''D. andersoni'' **Region (US): Southeast, South-central, West, widespread

Viral

* Tick-borne meningoencephalitis **Organism:

TBEV Tick-borne encephalitis virus (TBEV) is a positive-strand RNA virus associated with tick-borne encephalitis in the genus '' Flavivirus''. Classification Taxonomy TBEV is a member of the genus '' Flavivirus''. Other close relatives, members ...

(FSME) virus, a flavivirus from family '' Flaviviridae'' **Vector: deer tick ('' Ixodes scapularis''), '' Ixodes ricinus'' (Europe), ''

Ixodes persulcatus ''Ixodes persulcatus'', the taiga tick, is a species of hard-bodied tick distributed from Europe through central and northern Asia to the People’s Republic of China and Japan. The sexual dimorphism of the species is marked, the male being much ...

'' (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 ca ...

/deer tick virus ** Organism: Powassan virus (POWV), a flavivirus from family '' Flaviviridae''. Lineage 2 POWV is also known as deer tick virus (DTV) ** Vector: ''

Ixodes cookei ''Ixodes cookei'' is a species of tick in the genus ''Ixodes''. It is normally a parasite of carnivorans, such as raccoons, foxes, and weasels, but has also been recorded on the groundhog (''Marmota monax'') and the marsh rice rat (''Oryzomys pal ...

'', '' Ix. scapularis'', ''Ix. marxi'', ''Ix. spinipalpus''m, ''

Dermacentor andersoni ''Dermacentor andersoni'', commonly known as the Rocky Mountain wood tick, is a hard tick, or member of the Ixodidae family, with three life stages including larvae, nymph, and finally adult An adult is a human or other animal that has reach ...

'', and '' D. variabilis'' ** Endemic to: North America and eastern Russia * Colorado tick fever **Organism: Colorado tick fever virus (CTF), a coltivirus from the '' Reoviridae'' **Vector: ''

'' **Region: US (West) * Crimean-Congo hemorrhagic fever **Organism: CCHF virus, a

nairovirus ''Orthonairovirus'' is a genus of viruses in the family ''Nairoviridae'' of the order Bunyavirales that include viruses with circular, negative-sense single stranded RNA. It got its name from the Nairobi sheep disease that affects the gastroin ...

, from the '' Bunyaviridae'' **Vector: ''

Hyalomma marginatum ''Hyalomma marginatum'' is a hard-bodied tick found on birds including the pale crag martin. This tick has been implicated in the transmission of Bahig virus, a pathogenic arbovirus previously thought to be transmitted only by mosquitoes. The ...

'', '' Rhipicephalus bursa'' **Region: Southern part of Asia, Northern Africa, Southern Europe *Severe febrile illness **Organism: Heartland virus, a phlebovirus, from the '' Bunyaviridae'' **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 ricinus''), mosquitoes **Region: Inner Mongolia but potentially more widespread

Protozoan

* Babesiosis **Organism: '' Babesia microti'', '' Theileria equi'' **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 c ...

**Organism: ''Cytauxzoon felis'' **Vector: '' Amblyomma americanum'' (Lone star tick) **Region (US): South, Southeast

Toxin

Tick paralysis Tick paralysis is the only tick-borne disease that is not caused by an infectious organism. The illness is caused by a neurotoxin produced in the tick's salivary gland. After prolonged attachment, the engorged tick transmits the toxin to its host. ...

**Cause: Toxin **Vector (US): ''

'' (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 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