Queensland Tick Typhus Research Articles

Prompt defervescence after initiation of treatment for rickettsial infections – time to dispense with the dogma?

IntroductionClinicians are commonly taught that if patients with suspected rickettsial disease have continuing fever after 48 hours of anti-rickettsial therapy, an alternative diagnosis is likely. MethodsThis retrospective study of patients hospitalised with scrub typhus and Queensland tick typhus (QTT) in tropical Australia, examined the time to defervescence after initiation of the patients’ anti-rickettsial therapy. It also identified factors associated with delayed defervescence (time to defervescence >48 hours after antibiotic commencement). ResultsOf the 58 patients, 32 (56%) had delayed defervescence. The median (interquartile range (IQR)) age of patients with delayed defervescence was 52 (37-62) versus 40 (28-53) years in those who defervesced within 48 hours (p = 0.05). Patients with delayed defervescence were more likely to require Intensive Care Unit (ICU) admission than those who defervesced within 48 hours (12/32 (38%) versus 3/26 (12%), p = 0.02). Even among patients not requiring ICU care, patients with delayed defervescence required a longer hospitalisation than that those who defervesced within 48 hours (median (IQR): 6 (3-8) versus 3 (2-5) days, p = 0.006). ConclusionsA significant proportion of patients with confirmed scrub typhus and QTT will remain febrile for >48 hours after appropriate anti-rickettsial therapy. Delayed defervescence is more common in patients with severe disease.

The Characteristics and Clinical Course of Patients with Scrub Typhus and Queensland Tick Typhus Infection Requiring Intensive Care Unit Admission: A 23-year Case Series from Queensland, Tropical Australia.

Scrub typhus and Queensland tick typhus (QTT)-rickettsial infections endemic to tropical Australia-can cause life-threatening disease. This retrospective study examined the clinical course of all patients with laboratory-confirmed scrub typhus or QTT admitted to the intensive care unit (ICU) of a tertiary referral hospital in tropical Australia between 1997 and 2019. Of the 22 patients, 13 had scrub typhus and nine had QTT. The patients' median (interquartile range [IQR]) age was 50 (38-67) years; 14/22 (64%) had no comorbidity. Patients presented a median (IQR) of seven (5-10) days after symptom onset. Median (IQR) Acute Physiology and Chronic Health Evaluation II scores were 13 (9-17) for scrub typhus and 13 (10-15) for QTT cases (P = 0.61). Following hospital admission, the median (IQR) time to ICU admission was five (2-19) hours. The median (IQR, range) length of ICU stay was 4.4 (2.9-15.9, 0.8-33.8) days. Multi-organ support was required in 11/22 (50%), 5/22 (22%) required only vasopressor support, 2/22 (9%) required only invasive ventilation, and 4/22 (18%) were admitted for monitoring. Patients were ventilated using protective lung strategies, and fluid management was conservative. Standard vasopressors were used, indications for renal replacement therapy were conventional, and blood product usage was restrictive; 9/22 (41%) received corticosteroids. One patient with QTT died, and two (8%) additional patients with QTT developed purpura fulminans requiring digital amputation. Death or permanent disability occurred in 3/9 (33%) QTT and 0/13 scrub typhus cases (P = 0.055). Queensland tick typhus and scrub typhus can cause multi-organ failure requiring ICU care in otherwise well individuals. Queensland tick typhus appears to have a more severe clinical phenotype than previously believed.

Human Tick-Borne Diseases in Australia.

There are 17 human-biting ticks known in Australia. The bites of Ixodes holocyclus, Ornithodoros capensis, and Ornithodoros gurneyi can cause paralysis, inflammation, and severe local and systemic reactions in humans, respectively. Six ticks, including Amblyomma triguttatum, Bothriocroton hydrosauri, Haemaphysalis novaeguineae, Ixodes cornuatus, Ixodes holocyclus, and Ixodes tasmani may transmit Coxiella burnetii, Rickettsia australis, Rickettsia honei, or Rickettsia honei subsp. marmionii. These bacterial pathogens cause Q fever, Queensland tick typhus (QTT), Flinders Island spotted fever (FISF), and Australian spotted fever (ASF). It is also believed that babesiosis can be transmitted by ticks to humans in Australia. In addition, Argas robertsi, Haemaphysalis bancrofti, Haemaphysalis longicornis, Ixodes hirsti, Rhipicephalus australis, and Rhipicephalus sanguineus ticks may play active roles in transmission of other pathogens that already exist or could potentially be introduced into Australia. These pathogens include Anaplasma spp., Bartonella spp., Burkholderia spp., Francisella spp., Dera Ghazi Khan virus (DGKV), tick-borne encephalitis virus (TBEV), Lake Clarendon virus (LCV), Saumarez Reef virus (SREV), Upolu virus (UPOV), or Vinegar Hill virus (VINHV). It is important to regularly update clinicians' knowledge about tick-borne infections because these bacteria and arboviruses are pathogens of humans that may cause fatal illness. An increase in the incidence of tick-borne infections of human may be observed in the future due to changes in demography, climate change, and increase in travel and shipments and even migratory patterns of birds or other animals. Moreover, the geographical conditions of Australia are favorable for many exotic ticks, which may become endemic to Australia given an opportunity. There are some human pathogens, such as Rickettsia conorii and Rickettsia rickettsii that are not currently present in Australia, but can be transmitted by some human-biting ticks found in Australia, such as Rhipicephalus sanguineus, if they enter and establish in this country. Despite these threats, our knowledge of Australian ticks and tick-borne diseases is in its infancy.

Rickettsia australis and Queensland Tick Typhus: A Rickettsial Spotted Fever Group Infection in Australia.

Rickettsia australis, the etiologic agent of Queensland tick typhus (QTT), is increasingly being recognized as a cause of community-acquired acute febrile illness in eastern Australia. Changing human population demographics, climate change, and increased understanding of expanding vector distribution indicate QTT is an emerging public health threat. This review summarizes the epidemiology, pathogenesis, clinical features, treatment principles, and future directions of this disease. Increased recognition of QTT will enable consideration of and prompt treatment of R. australis infection by clinicians in Australia.

Clinical Manifestations and Outcomes of Rickettsia australis Infection: A 15-Year Retrospective Study of Hospitalized Patients.

Queensland tick typhus (QTT; Rickettsia australis) is an important cause of community-acquired acute febrile illness in eastern Australia. Cases of QTT were identified retrospectively from 2000 to 2015 at five sites in Northern Brisbane through a pathology database. Those included had a fourfold rise in spotted fever group (SFG)-specific serology, a single SFG-specific serology ≥ 256 or SFG-specific serology ≥ 128 with a clinically consistent illness. Cases were excluded on the basis of clinical unlikelihood of QTT infection. Thirty-six cases were included. Fever was found in 34/36 (94%) patients. Rash occurred in 83% of patients with maculopapular being the dominant morphology (70%). Thrombocytopenia, lymphopenia, and raised transaminases were common and occurred in 58%, 69%, and 89% of patients, respectively. Thirty-one of 36 (86%) patients received antibiotic therapy (usually doxycycline) and the time to correct antibiotic (from admission) ranged from 3 to 120 h (mean 45.5 h). Four of 36 (11%) required intensive care unit (ICU) admission for severe sepsis and end-organ support. There were no deaths. QTT has a wide range of clinical and laboratory features. Early and appropriate antimicrobial therapy is important and may prevent severe disease. Further prospective studies are required to identify factors associated with severe infection and sepsis.

Epidemiology and Characteristics of Rickettsia australis (Queensland Tick Typhus) Infection in Hospitalized Patients in North Brisbane, Australia.

Queensland tick typhus (QTT; Rickettsia australis) is a spotted fever group (SFG) rickettsial infection endemic to Australia. It is an underreported and often unrecognized illness with poorly-defined epidemiology. This article describes epidemiological features and the geographical distribution of QTT in hospitalized patients. Cases of QTT were identified retrospectively from 2000–2015 at five sites in Northern Brisbane through a pathology database. Included cases had a four-fold rise in SFG-specific serology, a single SFG-specific serology ≥256 or an SFG-specific serology ≥128 with a clinically consistent illness. Of the fifty cases identified by serology, 36 were included. Age ranged from 3–72 years (with a mean of 39.5 years) with a male-to-female ratio of 1:1.1. Fifteen of 36 (42%) study participants had hobbies and/or occupations linked with the acquisition of the disease. Seventeen of 36 (47%) identified a tick bite in the days preceding presentation to hospital, and reported exposure to a known animal host was minimal (25%). QTT infection occurred throughout the year, with half of the cases reported between April and July. Recent ecological and sociocultural changes have redefined the epidemiology of this zoonotic illness, with areas of higher infection risk identified. Heightened public health awareness is required to monitor QTT disease activity.

Tick‐borne infectious diseases in Australia

Tick bites in Australia can lead to a variety of illnesses in patients. These include infection, allergies, paralysis, autoimmune disease, post-infection fatigue and Australian multisystem disorder. Rickettsial (Rickettsia spp.) infections (Queensland tick typhus, Flinders Island spotted fever and Australian spotted fever) and Q fever (Coxiella burnetii) are the only systemic bacterial infections that are known to be transmitted by tick bites in Australia. Three species of local ticks transmit bacterial infection following a tick bite: the paralysis tick (Ixodes holocyclus) is endemic on the east coast of Australia and causes Queensland tick typhus due to R. australis and Q fever due to C. burnetii; the ornate kangaroo tick (Amblyomma triguttatum) occurs throughout much of northern, central and western Australia and causes Q fever; and the southern reptile tick (Bothriocroton hydrosauri) is found mainly in south-eastern Australia and causes Flinders Island spotted fever due to R. honei. Much about Australian ticks and the medical outcomes following tick bites remains unknown. Further research is required to increase understanding of these areas.

Ixodes holocyclus Tick-Transmitted Human Pathogens in North-Eastern New South Wales, Australia.

A group of 14 persons who live in an area of Australia endemic for the Australian paralysis tick, Ixodes holocyclus, and who were involved in regularly collecting and handling these ticks, was examined for antibodies to tick-transmitted bacterial pathogens. Five (36%) had antibodies to Coxiella burnetii, the causative agent of Q fever and three (21%) had antibodies to spotted fever group (SFG) rickettsiae (Rickettsia spp). None had antibodies to Ehrlichia, Anaplasma, Orientia, or Borrelia (Lymedisease) suggesting that they had not been exposed to these bacteria. A total of 149 I. holocyclus ticks were examined for the citrate synthase (gltA) gene of the SFG rickettsiae and the com1 gene of C. burnetii; 23 (15.4%) ticks were positive for Rickettsia spp. and 8 (5.6%) positive for Coxiella spp. Sequencing of fragments of the gltA gene and the 17 kDa antigen gene from a selection of the ticks showed 99% and 100% homology, respectively, to Rickettsia australis, the bacterium causing Queenslandtick typhus. Thus, it appears that persons bitten by I. holocyclus in NE NSW, Australia have an approximate one in six risk of being infected with R. australis. Risks of Q fever were also high in this region but this may have been due to exposure by aerosol from the environment rather than by tick bite. A subset of 74 I. holocyclus ticks were further examined for DNA from Borrelia spp., Anaplasma spp. and Ehrlichia spp. but none was positive. Some of these recognised human bacterial pathogens associated with ticks may not be present in this Australian tick species from northeastern New South Wales.

Queensland tick typhus: three cases with unusual clinical features

Queensland tick typhus (QTT), caused by Rickettsia australis, is usually a relatively mild illness but can occasionally be severe. We describe three cases of probable QTT with unusual clinical features, namely splenic infarction, fulminant myopericarditis and severe leukocytoclastic vasculitis. QTT may present with uncommon clinical features in addition to the more common manifestations. A high index of suspicion enables specific antibiotic therapy that may hasten recovery.

Genome Sequence of Rickettsia australis, the Agent of Queensland Tick Typhus

Rickettsia australis strain Phillips(T) was isolated in Queensland, Australia, in 1950. It is the tick-borne agent of Queensland tick typhus, a disease endemic in Australia. The 1.29-Mb genome sequence of this bacterium is highly similar to that of Rickettsia akari but contains two plasmids.

Severe Queensland tick typhus complicated by diabetes in south‐eastern Queensland

Severe Queensland tick typhus complicated by diabetes in south‐eastern Queensland

Diagnosis of Queensland Tick Typhus and African Tick Bite Fever by PCR of Lesion Swabs

We report 3 cases of Queensland tick typhus (QTT) and 1 case of African tick bite fever in which the causative rickettsiae were detected by PCR of eschar and skin lesions in all cases. An oral mucosal lesion in 1 QTT case was also positive.

Rickettsioses in Australia

The rickettsial diseases of Australia are described in their chronological order of discovery. The include epidemic typhus (R. prowazekii); murine typhus (R. typhi) found Australia-wide; scrub typhus (O. tsutsugamushi) only in tropical, northen Australia; Q. fever (C. burnetti) found Australia-wide; Queensland tick typhus (R. australis) along the east coast of Australia; Flinders Island spotted fever (R. honei) in southeast Australia; Variant Flinders Island spotted fever (R. honei, strain "marmionii") in eastern Australia; Rickettsia felis, Western Australia; eight new RFG rickettsiae from ticks (of unknown pathogenicity); and two nonhuman pathogens in A. platys (dogs) and A. marginale (cattle).

Severe Spotted Fever Group Rickettsiosis, Australia

We report 3 cases of spotted fever group rickettsial infection (presumed Queensland tick typhus) in residents of northern Queensland, Australia, who had unusually severe clinical manifestations. Complications included renal failure, purpura fulminans, and severe pneumonia. Clinical illness caused by Rickettsia australis may not be as benign as previously described.

Three Rickettsioses, Darnley Island, Australia

We report 3 rickettsioses on Darnley Island, Australia, in the Torres Strait. In addition to previously described cases of Flinders Island spotted fever (Rickettsia honei strain “marmionii”), we describe 1 case of Queensland tick typhus (R. australis) and 2 cases of scrub typhus caused by a unique strain (Orientia tsutsugamushi).

Flinders Island Spotted Fever Rickettsioses Caused by “marmionii” Strain of Rickettsia honei, Eastern Australia

Abstract Australia has 4 rickettsial diseases: murine typhus, Queensland tick typhus, Flinders Island spotted fever, and scrub typhus. We describe 7 cases of a rickettsiosis, with an acute onset and symptoms of fever (100%), headache (71%), arthralgia (43%), myalgia (43%), cough (43%), maculopapular/petechial rash (43%), nausea (29%), pharyngitis (29%), lymphadenopathy (29%), and eschar (29%). Cases were most prevalent in autumn and from eastern Australia, including Queensland, Tasmania, and South Australia. One patient had a history of tick bite (Haemaphysalis novaeguineae). An isolate shared 99.2%, 99.8%, 99.8%, 99.9%, and 100% homology with the 17 kDa, ompA, gltA, 16S rRNA, and Sca4 genes, respectively, of Rickettsia honei. This Australian rickettsiosis has similar symptoms to Flinders Island spotted fever, and the strain is genetically related to R. honei. It has been designated the “marmionii” strain of R. honei, in honor of Australian physician and scientist Barrie Marmion.

Flinders Island Spotted Fever Rickettsioses Caused by “marmionii” Strain ofRickettsia honei,Eastern Australia

Australia has 4 rickettsial diseases: murine typhus, Queensland tick typhus, Flinders Island spotted fever, and scrub typhus. We describe 7 cases of a rickettsiosis with an acute onset and symptoms of fever (100%), headache (71%), arthralgia (43%), myalgia (43%), cough (43%), maculopapular/petechial rash (43%), nausea (29%), pharyngitis (29%), lymphadenopathy (29%), and eschar (29%). Cases were most prevalent in autumn and from eastern Australia, including Queensland, Tasmania, and South Australia. One patient had a history of tick bite (Haemaphysalis novaeguineae). An isolate shared 99.2%, 99.8%, 99.8%, 99.9%, and 100% homology with the 17 kDa, ompA, gltA, 16S rRNA, and Sca4 genes, respectively, of Rickettsia honei. This Australian rickettsiosis has similar symptoms to Flinders Island spotted fever, and the strain is genetically related to R. honei. It has been designated the "marmionii" strain of R. honei, in honor of Australian physician and scientist Barrie Marmion.

Queensland tick typhus as a cause of seizures and acute confusion

Queensland tick typhus is a rickettsial disease transmitted via a tick bite. The illness is usually mild, consisting of fever, myalgia and a rash. We present the case of a severe form of the illness which manifested as seizures and acute confusion. We highlight the need to consider this disease in the critically ill patient who presents with a febrile illness and a rash, and the need to consider empirical treatment in such patients.

A case of Queensland tick typhus

Medical Journal of AustraliaVolume 163, Issue 3 p. 167-167 Letter A case of Queensland tick typhus Ralph L Doherty, Ralph L Doherty Professor Emeritus Department of Social and Preventive Medicine, University of Queensland, 141 Sackville Street, Greenslopes, QLD, 4120Search for more papers by this author Ralph L Doherty, Ralph L Doherty Professor Emeritus Department of Social and Preventive Medicine, University of Queensland, 141 Sackville Street, Greenslopes, QLD, 4120Search for more papers by this author First published: 01 August 1995 https://doi.org/10.5694/j.1326-5377.1995.tb127988.xAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume163, Issue3August 1995Pages 167-167 RelatedInformation

Rapid detection and molecular characterization of australian human rickettsial isolates

Australia has a number of unique rickettsial diseases including Queensland Tick Typhus. More recently, Flinders Island Spotted Fever ( FISF ) of presumed rickettsial origin has been described. We have studied Australian human rickettsial disease from 2 perspectives. Firstly, we have detected rickettsial DNA in blood samples of 2 patients with FISF by DNA amplification utilizing the Polymerase Chain Reaction. Confirmation of the rickettsial origin of the amplified DNA was made by hybridization with a rickettsia-specific DNA probe. This probe, made from the genus-common 17 kilodalton antigen of <i>Rickettsia australis</i> has been fully characterised and incorporates non-radioactive detection of target molecules. We aim to develop this method to provide rapid diagnosis of rickettsial disease Secondly, by applying the molecular typing technique of ribosomal DNA hybridization we have investigated the DNA relatedness of Australian human rickettsial isolates from Queensland Tick Typhus and presumptive human rickettsial isolates from FISF. Digestion of purified rickettsial chromosomal DNA from human isolates with the restriction endonuclease Eco R1 revealed specific differences between rickettsial isolates from patients with Queensland Tick Typhus and FISF when probed with ribosomal DNA. Ongoing studies are in progress to establish the relatedness of these isolates.