Tick&Tick-borne diseases

Ticks are small arachnids in the order Parasitiformes. Along with mites, they constitute the subclass Acari. Ticks are ectoparasites (external parasites), living by hematophagy on the blood of mammals, birds, and sometimes reptiles and amphibians. Ticks are vectors of a number of diseases that affect both humans and other animals.

Despite their poor reputation among human communities, ticks may play an ecological role by culling infirm animals and preventing overgrazing of plant resources.

Tick-borne diseases, which afflict humans and other animals, are caused by infectious agents transmitted by tick bites. Tick-borne illnesses are caused by infection with a variety of pathogens, including rickettsia and other types of bacteria, viruses, and protozoa. 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. Currently (2016), there are 16 known tick-borne diseases of humans (four discovered since 2013).

Major tick-borne diseases include:

Bacteria

• Lyme disease or Borreliosis
• Lyme disease, also known as Lyme borreliosis, is an infectious disease caused by bacteria of the Borrelia type. The most common sign of infection is an expanding area of redness, known as erythema migrans, that begins at the site of a tick bite about a week after it has occurred. The rash is typically neither itchy nor painful. Approximately 25–50% of infected people do not develop a rash. Other early symptoms may include fever, headache and feeling tired. If untreated, symptoms may include loss of the ability to move one or both sides of the face, joint pains, severe headaches with neck stiffness, or heart palpitations, among others. Months to years later, repeated episodes of joint pain and swelling may occur. Occasionally, people develop shooting pains or tingling in their arms and legs. Despite appropriate treatment, about 10 to 20% of people develop joint pains, memory problems, and feel tired for at least six months.
  • Treatment: Antibiotics (Doxycycline in non pregnant adults, Amoxicillin in pregnant adults and children)

Doxycycline is an antibiotic that is used in the treatment of a number of types of infections caused by bacteria and protozoa. It is useful forbacterial pneumonia, acne, chlamydia infections, early Lyme disease,cholera and syphilis. It is also useful for the treatment of malariawhen used with quinine and for the prevention of malaria. Doxycycline can be used either by mouth or intravenously.

Doxycycline

Amoxicillin (amox), also spelled amoxycillin, is an antibiotic useful for the treatment of a number of bacterial infections. It is the first line treatment for middle ear infections. It may also be used for strep throat, pneumonia, skin infections, and urinary tract infections among others. It is taken by mouth.

Amoxicillin

• Relapsing fever (Tick-borne relapsing fever, different from Lyme disease due to different Borrelia species and ticks)
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  • 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
  • Rocky Mountain spotted fever (RMSF), also known as blue disease, is the most lethal and most frequently reported rickettsial illness in the United States. It has been diagnosed throughout the Americas. Some synonyms for Rocky Mountain spotted fever in other countries include “tick typhus,” “Tobia fever” (Colombia), “São Paulofever” or “febre maculosa” (Brazil), and “fiebre manchada” (Mexico). It is distinct from the viral tick-borne infection, Colorado tick fever. The disease is caused by Rickettsia rickettsii, a species of bacterium that is spread to humans by Dermacentor ticks. Initial signs and symptoms of the disease include sudden onset of fever, headache, and muscle pain, followed by development of rash. The disease can be difficult to diagnose in the early stages, and without prompt and appropriate treatment it can be fatal
  • Treatment: Antibiotic 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 in Laos
  • Symptoms:Most often small red spots, other symptoms are fever, muscle pain, headache and respiratory problemsTreatment: Broad band Antibiotic therapy are needed, it is likely that phenoxymethylpenicillin is sufficient.
• Ehrlichiosis anaplasmosis (formerly human granulocytic ehrlichiosis or HGE)
• Ehrlichiosis is a tickborne bacterial infection, caused by bacteria of the family Anaplasmataceae, genera Ehrlichia and Anaplasma. These obligate intracellular bacteria infect and kill white blood cells.
  The average reported annual incidence is 0.7 cases per million people.
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  • Anaplasmosis is a disease caused by a rickettsial parasite ofruminants, Anaplasma spp. The microorganism is gram-negative and occurs in the red blood cells. It is transmitted by natural means through a number of haematophagous species of ticks. Anaplasmosis can also be transmitted iatrogenically by the use of surgical, dehorning, castration, and tattooinstruments and hypodermic needles that are not disinfected between uses.
  Region (US): South-Atlantic South-Central
• Tularemia
  • Tularemia is a serious infectious disease caused by the intracellularbacterium Francisella tularensis. It causes fever, and sometimes ulceration at the site of entry and/or swelling of nearby lymph nodes.It can cause severe pneumonia.
  • Region (US): Southeast, South-Central, West, Widespread

Viruses

• Tick-borne meningoencephalitis
  • Tick-borne encephalitis (TBE) is a viral infectious disease involving the central nervous system. The disease most often manifests asmeningitis, encephalitis, or meningoencephalitis. Although TBE is most commonly recognized as a neurological disorder, mild fever can also occur. Long-lasting or permanent neuropsychiatric sequelae are observed in 10 to 20% of infected patients.
  Endemic to: Europe and Northern Asia
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• Colorado tick fever
  • Organism: Colorado Tick Fever virus (CTF), a coltivirus from Reoviridae
  • Colorado tick fever (CTF) (also called mountain tick fever, American tick fever, and American mountain tick fever) 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 fever.
  • Region: US (West)
• Crimean-Congo hemorrhagic fever
  • Organism: CCHF virus, a nairovirus, from Bunyaviridae
  • Crimean–Congo hemorrhagic fever (CCHF) is a widespread tick-borne viral disease that is endemic in Africa, the Balkans, the Middle East and Asia. The virus is a member of the Bunyaviridae family ofRNA viruses. It is a zoonotic disease carried by several domestic and wild animals. While clinical disease is rare in infected animals, it is severe in infected humans, with a mortality rate of 10-40%. Outbreaks of illness are usually attributable to Hyalomma tick bites or contact with infected animals or people.
  Region: Southern part of Asia, Northern Africa, Southern Europe
• Severe Febrile Illness
  • Organism: Heartland virus, a phlebovirus, from Bunyaviridae
  • Vector: Lone Star Tick (Amblyomma americanum)
  • Region: Missouri and Tennessee, United States

Protozoa

• Babesiosis
  • Organism: Babesia microti, B. equi
  • Babesiosis is a malaria-like parasitic disease caused by infection with Babesia, a genus of Apicomplexa. Human babesiosis is an uncommon but emerging disease in the Northeastern and Midwestern United States and parts of Europe, and sporadic throughout the rest of the world. It occurs in warm months. Ticks transmit the human strain of babesiosis, so it often presents with other tick-borne illnesses such as Lyme disease. After trypanosomes,Babesia is thought to be the second-most common blood parasite of mammals, and they can have a major impact on health of domestic animals in areas without severe winters. In cattle, a major host, the disease is known as Texas cattle fever, redwater, or piroplasmosis.
  Region (US): Northeast West Coast
• Cytauxzoonosis
  • Organism: C. felis
  • 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 Florida bobcat, eastern bobcat, Texas cougar, and a white tiger in captivity. C. felis infection is limited to the family felidae which means that C. felis poses no zoonotic (transmission to humans) risk or agricultural (transmission to farm animals) risk. Until recently it was believed that after infection with C. felis, pet cats almost always died. As awareness of C. felis has increased it has been found that treatment is not always futile. More cats have been shown to survive the infection than was previously thought. New treatments offer as much as 60% survival rate.
  Region (US): South, Southeast

Toxin

• Tick paralysis
  • Cause: Toxin
  • 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. The incidence of tick paralysis is unknown. Patients can experience severe respiratory distress (similar to anaphylaxis).
  Region (US): East
  • Region (Australia): East