Queensland tick typhus

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Queensland tick typhus
Other namesAustralian tick typhus or Rickettsial spotted fever [1]
Specialty Infectious disease

Queensland tick typhus [2] is a zoonotic disease [3] caused by the bacterium Rickettsia australis . [4] It is transmitted by the ticks Ixodes holocyclus and Ixodes tasmani . [5]

Contents

Signs and symptoms

A presentation of an eschar on a person's back due to tick bite. This suggests that this may be the initial site of contact. EscharFromTick.jpg
A presentation of an eschar on a person's back due to tick bite. This suggests that this may be the initial site of contact.

Queensland tick typhus is a tick-borne disease. Onset of the illness is variable; there is an incubation period of 2 to 14 days after being bitten by the infected tick. [6] The clinical features of this illness include fever, headache, an eschar at the site of the tick bite, erythematous eruption [6] and satellite lymphadenopathy. [7] Queensland tick typhus symptomatically resembles Rocky Mountain spotted fever, a less severe tick-borne disease. [7] If left untreated for longer than one to two weeks, the disease can take longer to recover from and pose a heightened risk of pneumonitis, encephalitis, septic shock, or even death. In some cases, even after the initial rash is cleared, the person may still experience prolonged lethargy or fatigue, which is common in such rickettsial infections. [6]

Causes

Queensland tick typhus is caused by the bacteria Rickettsia australis from the genus Rickettsia . [8]

General life cycle of a typical tick Life cycle of ticks family ixodidae.PNG
General life cycle of a typical tick

Tick life cycle

The tick life cycle consists of four stages: egg, larva, nymph, and adult. [9] An adult female tick can lay over a thousand eggs in her lifetime. [10] Once a tick hatches from an egg, it enters the larvae stage, where it must attach to any available host and begin feeding. After it has fed, it detaches and molts, entering the larger nymph stage. In this stage it must reattach to a larger host and feed again, whereupon it detaches and molts again. This results in the adult stage, where it feeds one last time and is able to sexually reproduce. [9]

The stage when ticks are most able to transmit this disease is the nymph stage. They are also the most dangerous in this stage since they are usually less than two millimeters in size and can stay virtually undetected until they are done feeding.[ citation needed ]

Transmission

Queensland tick typhus is transmitted primarily by two types of tick: Ixodes holocyclus and Ixodes tasmani. After the initial attachment to a host, depending on the species and life stage of the tick, it takes anywhere from 10 minutes to 2 hours for it to begin to feed. [11] Once a tick attaches, it can stay on a host for about 12 to 18 hours and then falls off when full. A tick must be attached for a long period of time to transmit bacteria. A tick that appears flat and small probably has not eaten yet. [12]

Pathogenesis

After transmission from the infected tick, the bacterium Rickettsia australis enters the body via the bloodstream. The first sign of disease is damage to the skin's microcirculation, which results in a rash. [13] From there, the damage continues further into vital organs and can ultimately result in sepsis with multi-organ failure if left untreated. [14]

Diagnosis

This disease can be challenging to diagnose because the initial signs are non-descript and relatively common. [6] Analyzing recent travel history can be vital in the beginning stages of treatment. Serological assays are the best means of diagnosing this disease, with the indirect microimmunofluorescence assay (IFA) being considered the best tool. However, underlying illnesses, such as rheumatologic and other immune-mediated disorders, can lead to false positives. [14] To combat these limitations, a PCR test may also be used; this test looks for rickettsial DNA. It can sensitively detect the target DNA in a sample taken from an eschar or blood during the first few days of infection. [6]

Prevention

There is no vaccine available for this disease, so to prevent infection, the US CDC recommends taking personal safety measures when venturing out into areas known to harbour ticks.[ citation needed ]

Before going into these areas, the following preparations should be followed:

After you return from these areas, the following precautions should be taken to prevent ticks from entering your home:

Treatment

Early treatment for Queensland tick typhus is relatively simple. It includes a course of oral antibiotics such as doxycycline or chloramphenicol. [6] If a patient cannot take the medication orally, then the antibiotics are given intravenously by a medical professional.[ citation needed ]

Epidemiology

Queensland tick typhus is endemic to Australia. [16] Since there is no compulsory reporting of rickettsial infections in Australia, it can be difficult to monitor the geographical distribution of this disease and have an accurate count of the number of cases occurring each year. [17] The disease is most common along the east coast of Australia, coinciding with the geographic range of its tick vectors. [17]

History

This disease was noted during World War II among Australian soldiers undergoing basic training on the Atherton Tableland in Queensland. [18] It is most common along the east coast of Australia, including that of Queensland. [6]

See also

Related Research Articles

<i>Rickettsia</i> Genus of bacteria

Rickettsia is a genus of nonmotile, gram-negative, nonspore-forming, highly pleomorphic bacteria that may occur in the forms of cocci, bacilli, or threads. The term "rickettsia" has nothing to do with rickets ; the bacterial genus Rickettsia instead was named after Howard Taylor Ricketts, in honor of his pioneering work on tick-borne spotted fever.

<span class="mw-page-title-main">Rocky Mountain spotted fever</span> Human disease

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 bleeding and starts on the wrists and ankles. Other symptoms may include muscle pains and vomiting. Long-term complications following recovery may include hearing loss or loss of part of an arm or leg.

Ehrlichiosis is a tick-borne disease of dogs usually caused by the rickettsial agent Ehrlichia canis. Ehrlichia canis is the pathogen of animals. Humans can become infected by E. canis and other species after tick exposure. German Shepherd Dogs are thought to be susceptible to a particularly severe form of the disease; other breeds generally have milder clinical signs. Cats can also be infected.

<span class="mw-page-title-main">Boutonneuse fever</span> Medical condition

Boutonneuse fever is a fever as a result of a rickettsial infection caused by the bacterium Rickettsia conorii and transmitted by the dog tick Rhipicephalus sanguineus. Boutonneuse fever can be seen in many places around the world, although it is endemic in countries surrounding the Mediterranean Sea. This disease was first described in Tunisia in 1910 by Conor and Bruch and was named boutonneuse due to its papular skin-rash characteristics.

<span class="mw-page-title-main">Scrub typhus</span> Disease caused by O. tsutsugamushi

Scrub typhus or bush typhus is a form of typhus caused by the intracellular parasite Orientia tsutsugamushi, a Gram-negative α-proteobacterium of family Rickettsiaceae first isolated and identified in 1930 in Japan.

<i>Rickettsia rickettsii</i> Species of bacterium

Rickettsia rickettsii is a gram-negative, intracellular, coccobacillus bacterium that is around 0.8 to 2.0 μm long. R. rickettsii is the causative agent of Rocky Mountain spotted fever. R. rickettsii is one of the most pathogenic Rickettsia strains. It affects a large majority of the Western Hemisphere and small portions of the Eastern Hemisphere.

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. 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.

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.

<i>Ixodes holocyclus</i> Species of tick

Ixodes holocyclus, commonly known as the Australian paralysis tick, is one of about 75 species in the Australian tick fauna and is considered the most medically important. It can cause paralysis by injecting neurotoxins into its host. It is usually found in a 20-kilometre wide band following the eastern coastline of Australia. Within this range Ixodes holocyclus is the tick most frequently encountered by humans and their pets. As this area also contains Australia's most densely populated regions, bites on people, pets and livestock are relatively common.

<span class="mw-page-title-main">Meningoencephalitis</span> Medical condition

Meningoencephalitis, also known as herpes meningoencephalitis, is a medical condition that simultaneously resembles both meningitis, which is an infection or inflammation of the meninges, and encephalitis, which is an infection or inflammation of the brain tissue.

A rickettsiosis is a disease caused by intracellular bacteria.

<i>Orientia tsutsugamushi</i> Species of bacterium

Orientia tsutsugamushi is a mite-borne bacterium belonging to the family Rickettsiaceae and is responsible for a disease called scrub typhus in humans. It is a natural and an obligate intracellular parasite of mites belonging to the family Trombiculidae. With a genome of only 2.0–2.7 Mb, it has the most repeated DNA sequences among bacterial genomes sequenced so far. The disease, scrub typhus, occurs when infected mite larvae accidentally bite humans. Primarily indicated by undifferentiated febrile illnesses, the infection can be complicated and often fatal.

<i>Rhipicephalus sanguineus</i> Species of species of tick found worldwide

Rhipicephalus sanguineus, commonly called the brown dog tick, kennel tick, or pantropical dog tick, is a species of tick found worldwide, but more commonly in warmer climates. This species is unusual among ticks in that its entire lifecycle can be completed indoors. The brown dog tick is easily recognized by its reddish-brown color, elongated body shape, and hexagonal basis capituli. Adults are 2.28 to 3.18 mm in length and 1.11 to 1.68 mm in width. They do not have ornamentation on their backs.

Rickettsia typhi is a small, aerobic, obligate intracellular, rod shaped gram negative bacterium. It belongs to the typhus group of the Rickettsia genus, along with R. prowazekii. R. typhi has an uncertain history, as it may have long gone shadowed by epidemic typhus. This bacterium is recognized as a biocontainment level 2/3 organism. R. typhi is a flea-borne disease that is best known to be the causative agent for the disease murine typhus, which is an endemic typhus in humans that is distributed worldwide. As with all rickettsial organisms, R. typhi is a zoonotic agent that causes the disease murine typhus, displaying non-specific mild symptoms of fevers, headaches, pains and rashes. There are two cycles of R. typhi transmission from animal reservoirs containing R. typhi to humans: a classic rat-flea-rat cycle that is most well studied and common, and a secondary periodomestic cycle that could involve cats, dogs, opossums, sheep, and their fleas.

<span class="mw-page-title-main">African tick bite fever</span> Medical condition

African tick bite fever (ATBF) is a bacterial infection spread by the bite of a tick. Symptoms may include fever, headache, muscle pain, and a rash. At the site of the bite there is typically a red skin sore with a dark center. The onset of symptoms usually occurs 4–10 days after the bite. Complications are rare but may include joint inflammation. Some people do not develop symptoms.

Rickettsia australis is a bacterium that causes a medical condition called Queensland tick typhus. The probable vectors are the tick species, Ixodes holocyclus and Ixodes tasmani. Small marsupials are suspected reservoirs of this bacterium.

<i>Rickettsia parkeri</i> Species of bacterium

Rickettsia parkeri is a gram-negative intracellular bacterium. The organism is found in the Western Hemisphere and is transmitted via the bite of hard ticks of the genus Amblyomma. R. parkeri causes mild spotted fever disease in humans, whose most common signs and symptoms are fever, an eschar at the site of tick attachment, rash, headache, and muscle aches. Doxycycline is the most common drug used to reduce the symptoms associated with disease.

Rickettsia helvetica, previously known as the Swiss agent, is a bacterium found in Dermacentor reticulatus and other ticks, which has been implicated as a suspected but unconfirmed human pathogen. First recognized in 1979 in Ixodes ricinus ticks in Switzerland as a new member of the spotted fever group of Rickettsia, the R. helvetica bacterium was eventually isolated in 1993. Although R. helvetica was initially thought to be harmless in humans and many animal species, some individual case reports suggest that it may be capable of causing a nonspecific fever in humans. In 1997, a man living in eastern France seroconverted to Rickettsia 4 weeks after onset of an unexplained febrile illness. In 2010, a case report indicated that tick-borne R. helvetica can also cause meningitis in humans.

Rickettsia felis is a species of bacterium, the pathogen that causes cat-flea typhus in humans, also known as flea-borne spotted fever. Rickettsia felis also is regarded as the causative organism of many cases of illnesses generally classed as fevers of unknown origin in humans in Africa.

<i>Ixodes tasmani</i> Species of tick (common marsupial tick)

Ixodes tasmani, colloquially known as the common marsupial tick, is an Australian species of hard-bodied tick. It is a common vector for certain pathogens. There are around 70 species of ticks found in Australia, 16 of which, Ixodes tasmani included, are able to parasitize humans.

References

  1. ↑ Spotted fevers, Department of Medical Entomology, University of Sydney
  2. ↑ "Queensland tick typhus". Archived from the original on December 6, 2010. Retrieved 2011-01-09.{{cite web}}: CS1 maint: bot: original URL status unknown (link), (unattributed material, possibly unedited translation)
  3. ↑ Stewart, Adam; Armstrong, Mark; Graves, Stephen; Hajkowicz, Krispin (2017-04-15). "Epidemiology and Characteristics of Rickettsia australis (Queensland Tick Typhus) Infection in Hospitalized Patients in North Brisbane, Australia". Tropical Medicine and Infectious Disease. 2 (2): 10. doi: 10.3390/tropicalmed2020010 . ISSN   2414-6366. PMC   6082070 . PMID   30270868.
  4. ↑ Rapini, Ronald P.; Bolognia, Jean L.; Jorizzo, Joseph L. (2007). Dermatology: 2-Volume Set. St. Louis: Mosby. p. 1130. ISBN   978-1-4160-2999-1.
  5. ↑ "MerckMedicus : Dorland's Medical Dictionary".
  6. 1 2 3 4 5 6 7 Thomas, Stephen (June 2018). "Queensland tick typhus (Rickettsia australis) in a man after hiking in rural Queensland". Australian Journal of General Practice. 47 (6): 359–360. doi: 10.31128/AJGP-10-17-4352 . PMID   29966177. S2CID   49641323.
  7. 1 2 "Medical Definition of Queensland tick typhus". MedicineNet. Retrieved 2021-12-09.
  8. ↑ Bechelli, Jeremy; Vergara, Leoncio; Smalley, Claire; Buzhdygan, Tetyana P.; Bender, Sean; Zhang, William; Liu, Yan; Popov, Vsevolod L.; Wang, Jin; Garg, Nisha; Hwang, Seungmin (2019). "Atg5 Supports Rickettsia australis Infection in Macrophages In Vitro and In Vivo". Infection and Immunity. 87 (1): e00651–18. doi:10.1128/IAI.00651-18. PMC   6300621 . PMID   30297526.
  9. 1 2 Mansourian, Erika (August 20, 2015). "The Life Cycle of the Tick from Eggs to Ambush". American Kennel Club. Retrieved 2021-12-09.
  10. ↑ "Understanding The Tick Life Cycle". Mosquito Control | Mosquito Joe | Eliminate Mosquitos. Retrieved 2021-12-09.
  11. ↑ "How ticks spread disease | CDC". Centers for Disease Control and Prevention. 2020-09-21. Retrieved 2021-12-09.
  12. ↑ "Tick-Borne Illnesses". Yale Medicine. Retrieved 2021-12-09.
  13. ↑ "Rickettsial infections". www.health.vic.gov.au. Retrieved 2021-12-09.
  14. 1 2 Stewart, Adam; Armstrong, Mark; Graves, Stephen; Hajkowicz, Krispin (2017-07-12). "Rickettsia australis and Queensland Tick Typhus: A Rickettsial Spotted Fever Group Infection in Australia". The American Journal of Tropical Medicine and Hygiene. 97 (1): 24–29. doi:10.4269/ajtmh.16-0915. ISSN   0002-9637. PMC   5508907 . PMID   28719297.
  15. 1 2 3 4 5 6 7 "Preventing tick bites on people | CDC". Centers for Disease Control and Prevention. 2020-07-01. Retrieved 2021-12-09.
  16. ↑ Wang, Jin-Mei; Hudson, Bernard J.; Watts, Matthew R.; Karagiannis, Tom; Fisher, Noel J.; Anderson, Catherine; Roffey, Paul (June 2009). "Diagnosis of Queensland Tick Typhus and African Tick Bite Fever by PCR of Lesion Swabs". Emerging Infectious Diseases. 15 (6): 963–965. doi:10.3201/eid1506.080855. ISSN   1080-6040. PMC   2727311 . PMID   19523304.
  17. 1 2 Stewart, Adam; Armstrong, Mark; Graves, Stephen; Hajkowicz, Krispin (2017-07-12). "Rickettsia australis and Queensland Tick Typhus: A Rickettsial Spotted Fever Group Infection in Australia". The American Journal of Tropical Medicine and Hygiene. 97 (1): 24–29. doi:10.4269/ajtmh.16-0915. ISSN   0002-9637. PMC   5508907 . PMID   28719297.
  18. ↑ "Rickettsial Diseases of Military Importance: An Australian Perspective - JMVH". jmvh.org. Retrieved 2021-12-09.
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