Ross River virus (RRV) is a small encapsulated single-strand RNA Alphavirus endemic to Australia, Papua New Guinea and other islands in the South Pacific. It is responsible for a type of mosquito-borne non-lethal but debilitating tropical disease known as Ross River fever, previously termed "epidemic polyarthritis". The virus is suspected to be enzootic in populations of various native Australian mammals, and has been found on occasion in horses.
|Ross River virus|
Ross River virus
Taxonomically, Ross River virus belongs to the virus genus Alphavirus, which is part of the family Togaviridae. The alphaviruses are a group of small enveloped single-strand positive-sense RNA viruses. RRV belongs to a subgroup of "Old World" (Eurasian-African-Australasian) alphaviruses, and is considered closely related to Sagiyama virus.
The virions (virus particles) themselves contain their genome in a protein capsid 700 Å in diameter. They are characterised by the presence of two glycoproteins (E1 and E2) embedded as trimeric dimers in a host-derived lipid envelope.
In 1928, an outbreak of acute febrile arthritis was recorded in Narrandera and Hay in New South Wales, Australia. In 1943, several outbreaks of arthralgia and arthritis were described in the Northern Territory, Queensland and the Schouten Islands, off the northern coast of Papua New Guinea. The name epidemic polyarthritis was coined for this disease. In 1956, an epidemic occurred in the Murray Valley which was compared to "acute viral polyarthritis" caused by Chikungunya virus. The Australian disease seemed to progress in milder fashion. In 1956, serological testing suggested an unknown new species of alphavirus (group A arbovirus) was the likely culprit.
In July and August 1956 and 1957, a virus recovered from mosquitoes collected near Tokyo, Japan, and was dubbed Sagiyama virus. This was considered a separate species for a time, but now is considered conspecific with Ross River virus.
In 1959, a new alphavirus was identified in mosquito (Ochlerotatus vigilax) samples trapped near Ross River, near Townsville, Queensland, Australia. Further serological testing showed that patients who had suffered "epidemic polyarthritis" in Queensland had antibodies to the virus. The new virus was named Ross River virus, and the disease Ross River fever.
The virus itself was first isolated in 1972 using suckling mice. It was found that RRV isolated from human serum could kill mice. However, the serum containing the virus that was used had come from an Aboriginal boy from Edward River, North Queensland. The child had a fever and a rash but no arthritis making the link between RRV and Ross River fever less than concrete.
The largest ever outbreak of the virus was in 1979–1980 and occurred in the western Pacific. The outbreak involved the islands of Fiji, Samoa, the Cook Islands, and New Caledonia. However, RRV was later isolated in humans following a series of epidemic polyarthritis outbreaks in Fiji, Samoa and the Cook Islands during 1979. RRV was isolated in an Australian patient suffering from Ross River fever in 1985.
In 2010, Ross River virus was found to have made its way to the Aundh area in Pune, India and spread to other parts of the city. A tourist to Australia probably returned infected with the virus. The RRV infection is characterised by inflammation and pain to multiple joints. Hydration by sufficient fluid intake is recommended to ensure that the fever does not rise to very dangerous levels. It is recommended that a doctor be consulted immediately as regular paracetamol gives only temporary reprieve from the fever.
In rural and regional areas of Australia, the continued prevalence of Ross River virus is thought to be supported by natural reservoirs such as large marsupial mammals. Antibodies to Ross River virus have been found in a wide variety of placental and marsupial mammals, and also in a few bird species. It is not presently known what reservoir hosts support Ross River virus in metropolitan areas such as Brisbane.
The southern saltmarsh mosquito (Aedes camptorhynchus), which is known to carry the Ross River virus, was discovered in Napier, New Zealand, in 1998. Due to an 11-year program by the New Zealand Ministry of Health, and later the Ministry of Agriculture & Fisheries, the species was declared completely eradicated from New Zealand in July 2010. As of September 2006, there has never been a report of a case of Ross River virus acquired within New Zealand.
Separate mosquito species may act as vector, widespread across areas and seasonal/geographical locations. In southern and northern regions, the Aedes group (camptorhynchus and vigilax) are the main RRV carriers. However, inland the Culex annulirostris is the main carrier with Aedes mosquitoes becoming active during wet seasons.
Due to the expansion and housing demand in the south west of Western Australia, residential development is occurring closer to wetlands despite that the ecosystem is known for mosquito breeding. Particularly in the Peel region where living near water is desirable for aesthetic value. Over the decade of June 2011 – 2012 the population increased by 44,000 residents averaging a rate of 4.5 per cent per annum. In June 2013 the Peel region accounted for approximately five per cent of the State's population and predicted to account for around 6.7 per cent of Western Australia's population by 2031.
A study comparing the risk of contracting Ross River virus (RRV) and the distance of the dwellings from Muddy Lakes. The reports showed within a one kilometre buffer zone there were approximately 1550 mosquitos in traps per night with 89% of them being Ae. camptorhynchus decreasing to approximately 450 mosquitos with 57% Ae. camptorhynchus at the six kilometre buffer zone. The study suggests that there is a significantly higher risk of contracting RRV when living closer to Muddy Lakes however, there was a rise in the two kilometre buffer zone of 3700 mosquitos with 94% Ae. camptorhynchus. A similar trend in the study same study conducted in the Peel region resulting in less mosquitoes the further away the buffer distance.
In 1995–96 Leschenault and Capel-Busselton were affected by an outbreak of 524 cases of RRV disease. Although this occurred around a decade ago, the data analysed the total RRV cases per 1000 persons for each 500m buffer zone. This shows an elevated risk of contracting the disease if living in close proximity to the Leschenault Estuary, within 2 km being the strongest disease risk gradient.
Evidence shows that there is a strong correlation between contracting RRV when living in close proximity to wetlands in the south west of Western Australia. However, due to continuous growth and development of residential areas around these wetlands it is expected that problems with RRV disease will occur.
There are several factors that can contribute to an individual's risk for Ross River virus in Australia. These risks were trialed in a study conducted in tropical Australia which illustrate that factors such as camping, light coloured clothing, exposure to certain flora and fauna and specific protective mechanisms are able to increase or decrease the likelihood of contracting the virus. By increasing the frequency of camping the individual's risk increases eight-fold, suggesting that an increased exposure to wildlife increases risk. This is shown by the narrow 95% confidence interval of 1.07–4.35 within the study. For example, an individual's exposure to kangaroos, wallabies and bromeliad plants also increased risk, suggesting that they are reservoirs for infection, breeding sites for mosquitoes and potential vectors of the virus. Although these areas show a higher risk for the virus human should still enjoy the wildlife but consider that preventive mechanisms as increasingly important while camping.
Ross River virus can be easily prevented through small behavioural mechanisms which should be of high importance in tropical areas and during participation of outdoor activities. Firstly, insect repellent should be rigorously used as to prevent bites from insects that specifically include mosquitoes which are vectors that carry the disease. A study in tropical Australia shows a very narrow 95% confidence interval of 0.20–1.00 for a decrease in Ross River virus risk as a result of increased use of insect repellent, suggesting a strong correlation between the two. Following, burning citronella candles are based on the same principle, that it repels insects that are vectors of the virus. Burning such candles also show a strong correlation with decreased Ross River virus risk shown in the same study with a narrow 95% confidence interval of 0.10–0.78. Secondly, wearing light coloured clothing decrease the risk of Ross River virus three-fold. This is again based on the repelling of vectors such as mosquitoes through the use of bright colours. Lastly, high risk areas should be minimised by mechanisms of prevention that are applied within households. For example, screens should be fitted to windows and doors to prevent entry of insects carrying the virus and potential breeding areas such as open water containers or water holding plants should be removed. Therefore, specific climatic environments should be assessed for high risk factors and the appropriate precautions should be taken in response.
The study of RRV has been recently facilitated by a mouse model. Inbred mice infected with RRV develop hind-limb arthritis/arthralgia. The disease in mice, similar to humans, is characterised by an inflammatory infiltrate including macrophages which are immunopathogenic and exacerbate disease. Furthermore, recent data indicate that the serum component, C3, directly contributes to disease since mice deficient in the C3 protein do not suffer from severe disease following infection.
Ross River virus can cause multiple symptoms on someone who is infected, the most common being arthritis or joint pain. Other symptoms include a rash on the limbs of the body, which often occurs roughly 10 days after arthritis begins. Lymph nodes may enlarge, most commonly in the arm pits or groin region, and rarely a feeling of 'pins and needles' in the persons hands and feet, but only occurs in a small number of people. The virus also causes moderate symptoms in horses.
The symptoms of Ross River virus are important to recognise for early diagnosis and therefore early treatment. Symptoms have been illustrated in a case report of an infected Thuringian traveller returning from South-East Australia. This case showed flu-like symptoms that include fever, chills, headache and pains in the body. Additionally, joint pain arose in which some joints become swollen and joint stiffness was particularly noticeable. A clinical examination of the infected individual shows a significant decrease of specific antibodies despite the normal blood count levels. A rash is a good indication that is likely to occur but usually disappears after ten days. The symptoms of Ross River virus are important to be aware of so that early treatment can be administered before the virus worsens. The time between catching the disease and experiencing symptoms is anywhere between three days to three weeks, usually it takes about 1–2 weeks. A person can be tested for Ross River virus by a blood test, other illnesses may need to be excluded before diagnosis.
Testing for Ross River virus should occur in patients who are experiencing acute polyarthritis, tiredness and/or rashes (~90%) with a history of travel within areas prone to infection from the virus. Serology (blood tests) is the appropriate manner by which to diagnose Ross River virus. Within 7 days of infection, the virus produces Immunoglobulin M (IgM) and is a presumptive positive diagnosis. IgM may persist for months or even years and therefore false positives may be triggered by Barmah Forest virus, rubella, Q fever or rheumatoid factor. To completely test for Ross River virus, a second serology test must be conducted 10–14 days after the first. The patient may then be declared positive for Ross River virus infection if there is a 4-fold increase of IgM antibody count.
Ross River fever is also known as Ross River virus infection or Ross River virus disease. Ross River virus is named after the Ross River in Townsville, which is the place where it was first identified. Ross River fever is the most common mosquito-borne disease in Australia, and nearly 5000 people are reported to be infected with the virus each year.
Aedes (Aedimorphus) alboscutellatus is a species of zoophilic mosquito belonging to the genus Aedes. It is a member in Aedes niveus subgroup. It is found in Sri Lanka, Korea. It is one of the most common indoor human biting mosquitoes in the world with peak biting 20:00-22:00 and 04:00-06:00 hours. It is known to transmit disease-causing pathogens like Ross River virus and Barmah virus.Aedes camptorhynchus
Aedes camptorhynchus, the southern saltmarsh mosquito, is responsible for transmitting the Ross River virus, which causes Ross River fever.
The mosquito had become established in New Zealand, after it was accidentally transported from Australia to Hawke’s Bay, in 1998 from where it dispersed to another 10 localities mainly on the North Island. It was declared to be eradicated in 2010.Aedes polynesiensis
Aedes polynesiensis (also known as the Polynesian tiger mosquito) is only found in the South Pacific on the islands of Austral Islands, Cook Islands, Ellice Islands, Fiji Islands, Hoorn Islands, Marquesas Islands, Pitcairn Island, Samoa Islands, Society Islands, Tokelau Islands, Tuamotu Archipelago. It is a vector of dengue, Ross River virus, and lymphatic filariasis, and a probable vector of Zika virus. Adults lay eggs in natural and human-associated pools of freshwater. Common larval habitats include tree holes, holes in volcanic rock formations, coconut shells, water storage containers (drums), and discarded trash (including tires and bottles).Alphavirus
In biology and immunology, an Alphavirus belongs to group IV of the Baltimore classification of the Togaviridae family of viruses, according to the system of classification based on viral genome composition introduced by David Baltimore in 1971. Alphaviruses, like all other group IV viruses, have a positive sense, single-stranded RNA genome. There are thirty alphaviruses able to infect various vertebrates such as humans, rodents, fish, birds, and larger mammals such as horses as well as invertebrates. Transmission between species and individuals occurs mainly via mosquitoes, making the alphaviruses a member of the collection of arboviruses – or arthropod-borne viruses. Alphavirus particles are enveloped, have a 70 nm diameter, tend to be spherical (although slightly pleomorphic), and have a 40 nm isometric nucleocapsid.Barmah Forest virus
Barmah Forest virus is an RNA virus in the genus Alphavirus. This disease was named after the Barmah Forest in the northern Victoria region of Australia where it was first isolated in 1974. The first documented case in humans was in 1986.As of 2015, it has been found only in Australia. Although there is no specific treatment for infection with the Barmah Forest virus, the disease is non-fatal and most infected people recover. The virus was discovered in 1974 in mosquitoes in the Barmah Forest in northern Victoria. The virus has gradually spread from the sub-tropical northern areas of Victoria to the coastal regions of New South Wales, Queensland and Western Australia (WA). People are more likely to contract the disease in summer and autumn in Australia. In the south west of WA, however, spring has been found to have the highest incidence.Culex annulirostris
Culex annulirostris, commonly known as the common banded mosquito, is an insect native to Australia, Fiji, Micronesia, the Philippines and Indonesia. It is regarded as a serious pest species throughout its range.
Frederick Askew Skuse described the species in 1889 from specimens collected in the Blue Mountains and Berowra. The species name is derived from the Latin words annulus "ring" and rostrum "bill".
The female is a moderate-sized brown to dark brown mosquito, with a single pale prominent broad band on the middle third of its proboscis, and similar bands on its legs.It closely resembles the female of the related Cx. sitiens. The latter species has a narrower band on its proboscis.Breeding takes place anywhere there is standing water, from swamps and ponds to all kinds of man-made puddles—irrigation channels, bamboo stumps, cacao shells, the bottoms of canoes. The water can be clean or polluted, in sun or shade, and fresh or brackish.Culex annulirostris mosquitoes are active between spring and late autumn. During this time they appear most commonly at dusk, though can also be active during the day and indoors. They can travel 5–10 km from their place of birth and feed on mammals and birds. Only the female feeds on blood as it needs to consume protein to help in reproducing. The male drinks nectar.It is an important vector for a number of arboviruses, including Murray Valley encephalitis virus, Ross River virus, Barmah Forest virus, Kunjin virus and Japanese encephalitis, as well as dog heartworm and the roundworm Wuchereria bancrofti in New Guinea.There is evidence it carries myxomatosis.Epidemic polyarthritis
Epidemic polyarthritis is an outdated term that was formerly used to refer to polyarthritis caused by two mosquito-borne viruses endemic to Australasia:
Barmah Forest virus, which causes Barmah Forest Fever
Ross River virus (RRV), which causes Ross River FeverList of Aedes species
The mosquito genus Aedes includes the following species. Where known, the listings indicate whether the species bites humans, and any pathogens that the species is known to carry.
namesList of notifiable diseases
The following is a list of notifiable diseases arranged by country.Ochlerotatus
Ochlerotatus is a genus of mosquito - until 2000 was ranked as a subgenus of Aedes, but after Reinert work, this clade was upgraded at a generic level. Though this change causes virtually the re-naming of the subgenus species listed in, this and many aedini closelly related taxa are suffering an ongoing revision of its taxonomy and some authors still uses "old" names in scientific publications.Parramatta River virus
Parramatta River virus (PaRV) is an insect virus belonging to Flaviviridae and endemic to Australia. It was discovered in 2015. The virus was identified from the mosquito Aedes vigilax collected from Sydney under the joint research project by scientists at the University of Queensland and the University of Sydney. In experimental infections, the virus is unable to grow in vertebrate cells, but only in Aedes-derived mosquito cell lines. This suggests that the virus does not infect vertebrates. The name is given because it was discovered from Silverwater, a suburb of Sydney on the southern bank of the Parramatta River. The mosquitoes from which the virus was isolated were actually collected in 2007, and had been preserved since then. The study commenced only after the development of the technique of viral detection in mosquitoes in the University of Queensland.The virus was identified as a result of investigation on the outbreak of Ross River virus in 2015. Both the viruses are transmitted by the same mosquitoes, but PaRV is not transmitted to humans, unlike RRV. According to one of the co-authors, Cameron Webb of the University of Sydney, this unique transmission of PaRV could hold a key "to vaccinate mosquitoes and stop their bites making thousands of Australians sick every summer." The reason, explained by Jody Hobson-Peters of the University of Queensland, is that if mosquitoes (vectors for human diseases) are infected with the PaRV, then they will no longer be able to carry other human-infectious viruses.The virus was identified from the whole genome sequence using Sanger sequencing. The viral genome consists of 10,893 nucleotides and encodes a polyprotein of 3384 amino acids. Comparison with the genomes of other viruses showed that its closest relatives are the Mediterranean Ochlerotatus flavivirus (MoFV) isolated from Ochlerotatus mosquitoes in Spain, and the Hanko virus (HANKV) from Ochlerotatus mosquitoes in Finland (both identified in 2012). With MoFV its shares 72.7% nucleotide identity, and with HANKV the nucledotide similarity is 71.4%.Polyarthritis
Polyarthritis is any type of arthritis that involves 5 or more joints simultaneously. It is usually associated with autoimmune conditions and may be experienced at any age and is not sex specific.QIMR Berghofer Medical Research Institute
The QIMR Berghofer Medical Research Institute (QIMR Berghofer) is an Australian medical research institute located in Herston, Brisbane, in the state of Queensland. QIMR was established in 1945 by the Government of Queensland through the enactment of the Queensland Institute of Medical Research Act 1945 (Qld). Previously known as the Queensland Institute of Medical Research (QIMR), the original purpose of the Institute was to further the study of tropical diseases in North Queensland. The current Director is Professor Frank Gannon.RID Insect Repellent
RID is an Australian brand of personal insect repellent sold and distributed in Australia, New Zealand, worldwide and online.
It was the first insect repellent invented in Australia, in 1956. It is applied topically to exposed skin or clothing to repel mosquitoes, sandflies, midges, flies, fleas, ticks, head lice, mites and other insect pests, as well as leeches. RID is available in a variety of packsizes such as aerosols creams, and pump sprays. It is the only major brand of personal insect repellent that is Australian-made and -owned, and has been in production for over 57 years.
RID contains these active ingredients: DEET (N,N-diethyl-m-toluamide), Di-n-propyl isocinchomeronate (a fly repellent), N-octyl bicycloheptene dicarboximide (an insecticide synergist) and Triclosan (an antimicrobial agent which kills a broad range of bacteria). Although RID once contained DDT as an active ingredient, it has since been removed when the effects of this highly toxic substance became more known worldwide.
According to the American Mosquito Control Association's Web site, N,N-diethyl-3-methylbenzamide (DEET) remains the standard by which all other repellents are judged. DEET was developed by the U.S. Department of Agriculture and was registered for use by the general public in 1957. It is effective against mosquitoes, biting flies, chiggers, fleas and ticks. These insect repellents slowly evaporate into the air, producing an invisible chemical barrier around the areas on the body and clothes where it is applied, repelling incoming insects.RID was invented in 1956, after 3,000 hours of field research by inventor Doug H. Thorley. A bottle of RID is exhibited at the Queensland Museum in Australia.
RID insect repellents are used to repel insects which may carry a number of diseases, including; Ross River Virus, Dengue Fever, West Nile Virus, Malaria, Yellow Fever, Japanese B Encephalitis, Filariasis, Lyme Disease, Leishmaniasis, Typhus Fever, Plague and Eastern Equine Encephalitis.
RID is an insect repellent. It is not able to protect people from the actual diseases mentioned above, except to repel the insects that may transmit them.Ross River (Queensland)
The Ross River is a river located in northern Queensland, Australia. The 49-kilometre (30 mi) long river flows through the city of Townsville and empties into the Coral Sea. It is the major waterway flowing through Townsville and the city's main source of drinking water.The river is named in 1864 after William Alfred Ross (-1887), first publican of the settlement who later became a mayor of Townsville in 1868.Ross River fever
Ross River fever is a mosquito-borne infectious disease caused by infection with the Ross River virus. The illness is typically characterised by an influenza-like illness and polyarthritis. The virus is endemic to mainland Australia and Tasmania, the island of New Guinea, Fiji, Samoa, the Cook Islands, New Caledonia and several other islands in the South Pacific.Synovial membrane
The synovial membrane (also known as the synovial stratum, synovium or stratum synoviale) is a specialized connective tissue that lines the inner surface of capsules of synovial joints and tendon sheath. It makes direct contact with the fibrous membrane on the outside surface and with the synovial fluid lubricant on the inside surface. In contact with the synovial fluid at the tissue surface are many rounded macrophage-like synovial cells (type A) and also type B cells. Type A cells maintain the synovial fluid by removing wear-and-tear debris. As for type B cells, they produce hyaluronan, as well as other extracellular components in the synovial fluid.Togaviridae
Togaviridae is a family of viruses. Humans, mammals, birds, and mosquitoes serve as natural hosts. There are currently 31 species in this family in a single genus. Diseases associated with alphaviruses include arthritis and encephalitis.