View source for Medicine:Queensland tick typhus

{{Infobox medical condition (new)
| name            = Queensland tick typhus
| synonyms        =  '''Australian tick typhus''' or '''Rickettsial spotted fever'''<ref>[http://medent.usyd.edu.au/fact/spotfev.htm Spotted fevers] {{Webarchive|url=https://web.archive.org/web/20101229091917/http://medent.usyd.edu.au/fact/spotfev.htm |date=2010-12-29 }}, Department of Medical Entomology, University of Sydney</ref>
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| field           = [[Medicine:Infectious disease (medical specialty)|Infectious disease]]
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'''Queensland tick typhus'''<ref>{{cite web |url=http://knowledge-storage.com/medicine/37-medicine/62-queensland-tick-typhus |title=Queensland tick typhus |access-date=2011-01-09 |url-status=bot: unknown |archive-url=https://web.archive.org/web/20101206051404/http://knowledge-storage.com/medicine/37-medicine/62-queensland-tick-typhus |archive-date=December 6, 2010 }}, (unattributed material, possibly unedited translation)</ref> is a [[Biology:Zoonosis|zoonotic]] disease<ref>{{Cite journal|last1=Stewart|first1=Adam|last2=Armstrong|first2=Mark|last3=Graves|first3=Stephen|last4=Hajkowicz|first4=Krispin|date=2017-04-15|title=Epidemiology and Characteristics of Rickettsia australis (Queensland Tick Typhus) Infection in Hospitalized Patients in North Brisbane, Australia|journal=Tropical Medicine and Infectious Disease|volume=2|issue=2|pages=10|doi=10.3390/tropicalmed2020010|issn=2414-6366|pmc=6082070|pmid=30270868|doi-access=free}}</ref> caused by the bacterium ''[[Biology:Rickettsia australis|Rickettsia australis]]''.<ref name="Bolognia">{{cite book |author=Rapini, Ronald P. |author2=Bolognia, Jean L. |author3=Jorizzo, Joseph L. |title=Dermatology: 2-Volume Set |publisher=Mosby |location=St. Louis |year=2007 |pages=1130 |isbn=978-1-4160-2999-1 }}</ref>
It is transmitted by the [[Biology:Tick|tick]]s ''[[Biology:Ixodes holocyclus|Ixodes holocyclus]]'' and ''[[Biology:Ixodes tasmani|Ixodes tasmani]]''.<ref name="urlMerckMedicus : Dorlands Medical Dictionary">{{cite web |url=http://www.merckmedicus.com/pp/us/hcp/thcp_dorlands_content_split.jsp?pg=/ppdocs/us/common/dorlands/drlnd/eight_09/000112685.htm#000112685 |title=MerckMedicus : Dorland's Medical Dictionary }}{{Dead link|date=December 2023 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>

== Signs and symptoms ==
[[File:EscharFromTick.jpg|thumb|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 [[Medicine:Tick-borne disease|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.<ref name=":0">{{Cite journal|last=Thomas|first=Stephen|date=June 2018|title=Queensland tick typhus (Rickettsia australis) in a man after hiking in rural Queensland|url=https://www1.racgp.org.au/ajgp/2018/june/queensland-tick-typhus|journal=Australian Journal of General Practice|volume= 47| issue = 6|pages=359–360|doi=10.31128/AJGP-10-17-4352|pmid=29966177|s2cid=49641323|doi-access=free}}</ref> The clinical features of this illness include [[Medicine:Fever|fever]], [[Medicine:Headache|headache]], an [[Biology:Eschar|eschar]] at the site of the tick bite, [[Medicine:Erythema|erythema]]tous eruption<ref name=":0" /> and satellite [[Medicine:Lymphadenopathy|lymphadenopathy]].<ref name=":1">{{Cite web|title=Medical Definition of Queensland tick typhus|url=https://www.medicinenet.com/queensland_tick_typhus/definition.htm|access-date=2021-12-09|website=MedicineNet|language=en}}</ref>  Queensland tick typhus symptomatically resembles [[Medicine:Rocky Mountain spotted fever|Rocky Mountain spotted fever]], a less severe tick-borne disease.<ref name=":1" />  If left untreated for longer than one to two weeks, the disease can take longer to recover from and pose a heightened risk of [[Medicine:Pneumonitis|pneumonitis]], [[Medicine:Encephalitis|encephalitis]], [[Medicine:Septic shock|septic shock]], or even [[Biology:Death|death]]. In some cases, even after the initial rash is cleared, the person may still experience prolonged lethargy or [[Medicine:Fatigue|fatigue]], which is common in such [[Biology:Rickettsia|rickettsia]]l infections.<ref name=":0" />

== Causes ==
Queensland tick typhus is caused by the bacteria ''Rickettsia australis'' from the genus ''[[Biology:Rickettsia|Rickettsia]]''.<ref>{{Cite journal|last1=Bechelli|first1=Jeremy|last2=Vergara|first2=Leoncio|last3=Smalley|first3=Claire|last4=Buzhdygan|first4=Tetyana P.|last5=Bender|first5=Sean|last6=Zhang|first6=William|last7=Liu|first7=Yan|last8=Popov|first8=Vsevolod L.|last9=Wang|first9=Jin|last10=Garg|first10=Nisha|last11=Hwang|first11=Seungmin|title=Atg5 Supports Rickettsia australis Infection in Macrophages In Vitro and In Vivo|journal=Infection and Immunity|year=2019|volume=87|issue=1|pages=e00651–18|doi=10.1128/IAI.00651-18|pmc=6300621|pmid=30297526}}</ref>
[[File:Life cycle of ticks family ixodidae.PNG|thumb|283x283px|General life cycle of a typical tick]]

=== Tick life cycle ===
The tick life cycle consists of four stages: egg, larva, nymph, and adult.<ref name=":2">{{Cite web|date=August 20, 2015|first=Erika|last=Mansourian|title=The Life Cycle of the Tick from Eggs to Ambush|url=https://www.akc.org/expert-advice/health/this-is-the-lifecycle-of-the-tick/|access-date=2021-12-09|website=American Kennel Club|language=en}}</ref>  An adult female tick can lay over a thousand eggs in her lifetime.<ref>{{Cite web|title=Understanding The Tick Life Cycle|url=https://mosquitojoe.com/blog/understanding-the-tick-lifecycle/|access-date=2021-12-09|website=Mosquito Control {{!}} Mosquito Joe {{!}} Eliminate Mosquitos|language=en}}</ref>  Once a [[Biology:Tick|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.<ref name=":2" />

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|date=July 2023}}

=== 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.<ref>{{Cite web|date=2020-09-21|title=How ticks spread disease {{!}} CDC|url=https://www.cdc.gov/ticks/life_cycle_and_hosts.html|access-date=2021-12-09|website=Centers for Disease Control and Prevention|language=en-us}}</ref> 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.<ref>{{Cite web|title=Tick-Borne Illnesses|url=https://www.yalemedicine.org/conditions/tick-borne-illnesses|access-date=2021-12-09|website=Yale Medicine|language=en}}</ref>

== 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.<ref>{{Cite web|title=Rickettsial infections|url=http://www.health.vic.gov.au/infectious-diseases/rickettsial-infections|access-date=2021-12-09|website=www.health.vic.gov.au|language=en}}</ref> From there, the damage continues further into vital organs and can ultimately result in sepsis with multi-organ failure if left untreated.<ref name=":3">{{Cite journal|last1=Stewart|first1=Adam|last2=Armstrong|first2=Mark|last3=Graves|first3=Stephen|last4=Hajkowicz|first4=Krispin|date=2017-07-12|title=Rickettsia australis and Queensland Tick Typhus: A Rickettsial Spotted Fever Group Infection in Australia|url=https://www.ajtmh.org/view/journals/tpmd/97/1/article-p24.xml|journal=The American Journal of Tropical Medicine and Hygiene|language=EN|volume=97|issue=1|pages=24–29|doi=10.4269/ajtmh.16-0915|issn=0002-9637|pmc=5508907|pmid=28719297}}</ref>

== Diagnosis ==
This disease can be challenging to diagnose because the initial signs are non-descript and relatively common.<ref name=":0" />  Analyzing recent travel history can be vital in the beginning stages of treatment. [[Biology:Serology|Serological assays]] are the best means of diagnosing this disease, with the indirect [[Biology:Immunofluorescence|microimmunofluorescence]] assay (IFA) being considered the best tool. However, underlying illnesses, such as rheumatologic and other immune-mediated disorders, can lead to false positives.<ref name=":3" />  To combat these limitations, a [[Biology:Polymerase chain reaction|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.<ref name=":0" />

== 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.{{cn|date=April 2023}}

Before going into these areas, the following preparations should be followed:
* Wear protective clothing that will cover your arms and legs, with closed-toed shoes. Wearing long socks that you can tuck your pants into will provide an extra layer of safety, especially if you are walking in areas with tall grass for an extended period of time.<ref name=":4">{{Cite web|date=2020-07-01|title=Preventing tick bites on people {{!}} CDC|url=https://www.cdc.gov/ticks/avoid/on_people.html|access-date=2021-12-09|website=Centers for Disease Control and Prevention|language=en-us}}</ref>
* Use strong insect repellent such as [[Chemistry:DEET|DEET]] on your body and [[Chemistry:Permethrin|Permethrin]] on your clothes<ref name=":4" />
* If you are taking a pet with you, they should also be updated on all preventative medications, and a veterinarian should be consulted for any extra precautions.<ref name=":4" />

After you return from these areas, the following precautions should be taken to prevent ticks from entering your home:
* Check clothes and gear used for any ticks. Dry clothes should be put into a dryer on high heat for 10 minutes to effectively kill any small ticks that may not be visible to the naked eye. If the clothes are wet, then they should be washed with hot water then dried on high heat.<ref name=":4" />
* Each individual should shower within two hours of returning home since this can help wash off any unattached ticks.<ref name=":4" />
* Finally, a full-body check should be performed to ensure that there is no attached tick.<ref name=":4" />
* If a pet was taken with you, they should receive a bath and a full-body tick check as well to ensure that they are not carrying anything into the home.<ref name=":4" />

== Treatment ==
Early treatment for Queensland tick typhus is relatively simple. It includes a course of oral antibiotics such as [[Chemistry:Doxycycline|doxycycline]] or [[Chemistry:Chloramphenicol|chloramphenicol]].<ref name=":0" /> If a patient cannot take the medication orally, then the antibiotics are given intravenously by a medical professional.{{cn|date=April 2023}}

== Epidemiology ==
Queensland tick typhus is endemic to {{wipe|Australia}}.<ref>{{Cite journal|last1=Wang|first1=Jin-Mei|last2=Hudson|first2=Bernard J.|last3=Watts|first3=Matthew R.|last4=Karagiannis|first4=Tom|last5=Fisher|first5=Noel J.|last6=Anderson|first6=Catherine|last7=Roffey|first7=Paul|date=June 2009|title=Diagnosis of Queensland Tick Typhus and African Tick Bite Fever by PCR of Lesion Swabs|url=http://wwwnc.cdc.gov/eid/article/15/6/08-0855_article.htm|journal=Emerging Infectious Diseases|volume=15|issue=6|pages=963–965|doi=10.3201/eid1506.080855|issn=1080-6040|pmc=2727311|pmid=19523304}}</ref> Since there is no compulsory reporting of rickettsial infections in {{wipe|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.<ref name=":5">{{Cite journal|last1=Stewart|first1=Adam|last2=Armstrong|first2=Mark|last3=Graves|first3=Stephen|last4=Hajkowicz|first4=Krispin|date=2017-07-12|title=Rickettsia australis and Queensland Tick Typhus: A Rickettsial Spotted Fever Group Infection in Australia|journal=The American Journal of Tropical Medicine and Hygiene|language=en|volume=97|issue=1|pages=24–29|doi=10.4269/ajtmh.16-0915|issn=0002-9637|pmc=5508907|pmid=28719297}}</ref> The disease is most common along the east coast of {{wipe|Australia}}, coinciding with the geographic range of its tick vectors.<ref name=":5" />

== History ==
This disease was noted during [[Social:World War II|World War II]] among Australian soldiers undergoing basic training on the Atherton Tableland in Queensland.<ref>{{Cite web|title=Rickettsial Diseases of Military Importance: An Australian Perspective - JMVH|url=https://jmvh.org/article/rickettsial-diseases-of-military-importance-an-australian-perspective/|access-date=2021-12-09|website=jmvh.org}}</ref> It is most common along the east coast of Australia, including that of Queensland.<ref name=":0" />

== See also ==
* [[Medicine:Typhus|Typhus]]
* [[Medicine:North Asian tick typhus|North Asian tick typhus]]
* [[Medicine:Rocky Mountain spotted fever|Rocky Mountain spotted fever]]
* List of cutaneous conditions

== References ==
{{Reflist}}

== External links ==
{{Medical resources
|  DiseasesDB = 33840
|  ICD10 = {{ICD10|A|77|3|a|75}}
|  ICD9 = {{ICD9|082.3}}
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{{Gram-negative proteobacterial diseases}}

[[Category:Typhus]]
[[Category:Tick-borne diseases]]

{{Sourceattribution|Queensland tick typhus}}