In this issue

Microbiology Australia Microbiology Australia
Issue 4

Tick-borne Pathogens and Diseases

Vertical Transmission

I will begin this Vertical Transmission by highlighting the links between the ASM National Executive and our State branches, and the steps we are taking to strengthen interactions between these important ASM groups.

Tick-borne pathogens and diseases

Welcome to this edition of Microbiology Australia in which we examine the second most dangerous ectoparasite for humans, the tick (the most dangerous being without doubt the mosquito!), for the pathogens it carries and the diseases it can cause.

Laboratory diagnosis of human infections transmitted by ticks, fleas, mites and lice in Australia

A wide range of human pathogens (viruses, bacteria, protozoa) are transmitted by ticks, fleas, mites and lice worldwide. Some of these infections occur in Australia1, whereas others appear to be absent, although they may occur in returned travellers. The key to diagnosis is two-fold: recognition of the possibility of a vector-borne infection by the treating doctor and confirmation of the diagnosis in a diagnostic, microbiology laboratory. Laboratory diagnostic assays include culture (used rarely), nucleic acid amplification (used inc...

Could Australian ticks harbour emerging viral pathogens?

Tick-borne viruses contribute significantly to the disease burden in Europe, Asia and the US. Historically, some of the most well-known viruses from this group include the human pathogens, tick-borne encephalitis virus and Crimean-Congo haemorrhagic fever virus. More recently multiple emerging tick-borne viruses have been associated with severe disease in humans with Bourbon virus and Heartland virus isolated from patients in the US and severe fever with thrombocytopenia syndrome virus reported from China, Japan, and South Korea. Such examples ...

Tick-borne encephalitis and its global importance

Tick-borne encephalitis (TBE) is the most important tick-transmitted human viral disease in Europe and Asia with up to 10000 human cases annually. The etiologic agents of TBE are the three subtypes of tick-borne encephalitis virus (TBEV), a member of the genus Flavivirus in the family Flaviviridae. The Far-Eastern subtype and the Siberian subtype are both mainly transmitted by Ixodes persulcatus; the European subtype is mainly transmitted by Ixodes ricinus. Besides tick bite, TBEV can be transmitted by unpasteurised milk fr...

Ticks in Australia: endemics; exotics; which ticks bite humans?

At least 71 species of ticks occur in Australia; a further 33 or so species are endemic to its neighbours, New Guinea and New Zealand. The ticks of Australia and other parts of Australasia are phylogenetically distinct. Indeed, there are at least two lineages of ticks that are unique to Australasia: the genus Bothriocroton Klompen, Dobson & Barker, 2002; and the new genus Archaeocroton Barker & Burger, 2018. Two species of ticks that are endemic to Australia are notorious for feeding on humans: (i) Ixodes holocyclus, the ea...

Bacterial tick-associated infections in Australia: current studies and future directions

It may seem perplexing that there is any uncertainty in Australia about the existence of zoonotic tick-associated infections13. Outside this country, particularly in the northern hemisphere, tick-borne diseases such as human granulocytic anaplasmosis, babesiosis, Boutonneuse fever, ehrlichiosis, Lyme borreliosis, and tick-borne encephalitis, have well documented aetiologies, epidemiology, diagnostic methods, and treatments. Why is Australia different and what research is being conducted to address this i...

Tick-transmitted human infections in Asia

Vector-borne pathogens of human significance cause a predicted 17% of infectious diseases worldwide, of which, ~23% are tick transmitted1. Although second to mosquitoes in terms of impact, ticks are thought to carry a greater diversity of pathogens than other arthropod vectors2. Asia is a key region for tick-borne pathogens, with tick species typically restricted to latitudes below 60–55°N3 where the climate is warmer and wetter – from the steppe regions of Russia to the tropical rainforests o...

A concise overview on tick-borne human infections in Europe: a focus on Lyme borreliosis and tick-borne Rickettsia spp.

Ticks are blood-feeding external parasites of mammals. Almost all ticks belong to one of two major families, the Ixodidae or hard ticks, and the Argasidae or soft ticks. Ticks are responsible of transmitting many diseases called ‘tick-borne diseases'. Borrelia and Rickettsia spp., are the most important tick-transmitted bacterial pathogens circulating in Europe. In this review we will focus on the two tick-borne diseases caused by these bacterial pathogens, their vector, epidemiology, clinical diagnosis and sy...

Non-infectious illness after tick bite

Tick bites are common and may have non-infectious complications. Reactions range from local reactions to systemic syndromes, tick paralysis, mammalian meat allergy and tick anaphylaxis. Management revolves around prevention with vector avoidance and immediate removal of the tick if bitten. Treatment of bite reactions is usually symptomatic only with anti-histamines or corticosteroids. Adrenaline may be indicated for severe cases.

Bovine theileriosis in Australia: a decade of disease

Theileriosis refers to the clinical disease caused by organisms from the genus Theileria, tick-borne haemoprotozoans infecting a diverse range of mammalian hosts. In Australia, Theileria spp. have been identified in both domestic and wildlife species but the bovine parasite, Theileria orientalis, has received the most attention due to the emergence and spread of clinical disease over the past 12 years, particularly in cattle herds on the east coast. At an estimated $20million per annum, the burden to cattle production is si...

Variables affecting laboratory diagnosis of acute rickettsial infection

The reference standard for the confirmation of a recent rickettsial infection is by the observation of a four-fold or greater rise in antibody titres when testing paired acute and convalescent (two to four weeks after illness resolution) sera by serological assays (Figure 1). At the acute stage of illness, diagnosis is performed by molecular detection methods most effectively on DNA extracted from tissue biopsies (eschars, skin rash, and organs) or eschar swabs. Less invasive and more convenient samples such as blood and serum may also be used ...

Rethinking Coxiella infections in Australia

Coxiellaburnetii is the causative agent of coxiellosis in animals and Q fever in humans. Despite being a vaccine preventable disease, Q fever remains a frequently reported zoonotic infection in Australia. Recently, a Coxiella species was identified in brown dog ticks (Rhipicephalus sanguineus) in urban and rural regions of Australia. Further molecular characterisation revealed that it is genetically identical to ‘Candidatus Coxiella massiliensis’ (KM079627) descri...

EduCon 2018

Book reviews

Vale A/Professor Horst Werner Doelle (1/9/1932–6/9/2018)

Vale Dr David Leslie

Corrigendum to: ASM Summer Student Research Awards: 2018

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Volume 39 Number 4

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