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Other Arbovirus Infections

By

Thomas M. Yuill

, PhD, University of Wisconsin-Madison

Last full review/revision Aug 2021| Content last modified Aug 2021
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Arbovirus Overview of Arbovirus, Arenavirus, and Filovirus Infections Arbovirus (arthropod-borne virus) applies to any virus that is transmitted to humans and/or other vertebrates by certain species of blood-feeding arthropods, chiefly insects (flies and mosquitoes)... read more (arthropod-borne virus) applies to any virus that is transmitted to humans and/or other vertebrates by certain species of blood-feeding arthropods, chiefly insects (flies and mosquitoes) and arachnids (ticks).

Chikungunya disease

Chikungunya disease is an acute febrile illness followed by more chronic polyarthritis that can persist for months or years. Death is extremely rare.

Chikungunya disease is transmitted by Aedes mosquitoes and is common in Africa, India, Pakistan, Nepal, Guam, Southeast Asia, New Guinea, China, Mexico, South and Central America, islands in the Caribbean, Indian Ocean and Pacific, and limited areas of Europe. Limited local transmission has been identified in Florida, Puerto Rico, and the US Virgin Islands.

Prevention of chikungunya disease involves avoiding mosquito bites. No vaccine is available.

Mayaro disease

This dengue Dengue Dengue is a mosquito-borne disease caused by a flavivirus. Dengue fever usually results in abrupt onset of high fever, headache, myalgias, arthralgias, and generalized lymphadenopathy, followed... read more -like disease is transmitted by mosquitoes. It is common in Brazil and Bolivia, and a more recent case in Trinidad and a suspected case in Haiti suggest that there is potential for spread to other areas in the Americas that have abundant population of Aedes aegypti.. Mayaro virus is an alphavirus in the Togavirus family.

Prevention of Mayaro disease involves avoiding mosquito bites. No vaccine is available.

Oropouche fever

Oropouche virus is a Simbu group bunyavirus.

The oropouche virus is transmitted to humans by Culicoides paraensis, a species of biting midges (small flying insects) present in South and Central America and the Caribbean.

Transmission of the oropouche virus occurs in 2 cycles:

  • Wild

  • Urban-epidemic

In the wild cycle, the reservoir for the oropouche virus is wildlife (eg, primates, sloths, certain arthropods). In the urban-epidemic cycle, humans are the principal reservoir, and the infection cycle is human to human via the midge vector.

The oropouche virus has been moving closer to major cities in Brazil, and some public health officials think that the virus has major epidemic potential throughout the area in which it occurs. The World Health Organization recommends that oropouche fever be included in the clinical differential diagnosis for other common febrile arboviral infections (eg, chikungunya disease Chikungunya disease Arbovirus (arthropod-borne virus) applies to any virus that is transmitted to humans and/or other vertebrates by certain species of blood-feeding arthropods, chiefly insects (flies and mosquitoes)... read more , dengue Dengue Dengue is a mosquito-borne disease caused by a flavivirus. Dengue fever usually results in abrupt onset of high fever, headache, myalgias, arthralgias, and generalized lymphadenopathy, followed... read more , yellow fever Yellow Fever Yellow fever is a mosquito-borne flavivirus infection endemic in tropical South America and sub-Saharan Africa. Symptoms may include sudden onset of fever, relative bradycardia, headache, and... read more , Zika Zika Virus (ZV) Infections The Zika virus is a mosquito-borne flavivirus that is antigenically and structurally similar to the viruses that cause dengue, yellow fever, and West Nile virus. Zika virus infection is typically... read more ) (1 Arbovirus references Arbovirus (arthropod-borne virus) applies to any virus that is transmitted to humans and/or other vertebrates by certain species of blood-feeding arthropods, chiefly insects (flies and mosquitoes)... read more ).

Treatment is supportive.

No vaccine is available. Prevention of oropouche fever involves avoiding midge bites.

Tick-borne encephalitis

Tick-borne encephalitis is caused by a flavivirus that has 3 subtypes, European, Siberian, and Far Eastern.

Tick-borne encephalitis is transmitted to humans in focal areas extending from eastern France to northern Japan by the bite of infected hard–bodied ticks, Ixodes ricinus in Europe and Ixodes persulcatus in Siberia and the Far East. Ticks are both vector and virus reservoir, and small rodents are the primary amplifying host. Tick-borne encephalitis can also be acquired by ingesting unpasteurized dairy products (such as milk and cheese) from infected goats, sheep, or cows.

Cases occur from early spring to late summer when ticks are most active. Initially, a mild flu-like illness occurs; the illness usually clears up within a few days, but about 30% of patients develop more severe symptoms (eg, meningitis Overview of Meningitis Meningitis is inflammation of the meninges and subarachnoid space. It may result from infections, other disorders, or reactions to drugs. Severity and acuity vary. Findings typically include... read more , meningoencephalitis). Incidence is highest and severity of disease is greatest in people ≥ 50 years.

Tick-borne encephalitis is not a nationally notifiable disease in the US; however, the Centers for Disease Control and Prevention (CDC) reports that 5 cases of tick-borne encephalitis occurred among US travelers to Europe and China from 2000 through 2011 (2 Arbovirus references Arbovirus (arthropod-borne virus) applies to any virus that is transmitted to humans and/or other vertebrates by certain species of blood-feeding arthropods, chiefly insects (flies and mosquitoes)... read more ).

Tick-borne encephalitis should be suspected in travelers who have both of the following:

  • A nonspecific febrile illness that progresses to neuroinvasive disease within 4 weeks after arriving from an endemic area

  • Risk of tick exposure

The diagnosis of tick-borne encephalitis is usually made serologically by detection of specific IgM antibodies in blood or cerebrospinal fluid, which typically appear only after onset of neurologic manifestations. The virus that causes tick-borne encephalitis can sometimes be detected in serum by virus isolation or reverse transcriptase polymerase chain reaction (RT-PCR) earlier in disease before antibody titers have risen.

As with other viral meningoencephalitides, treatment is supportive.

Although no vaccines for tick-borne encephalitis are licensed or available in the US, there are several effective, inactivated tick-borne encephalitis vaccines available in Russia and Europe. Vaccination is recommended for people who work outdoors or engage in recreational activities in endemic areas and are at risk of tick exposure.

Powassan virus

In the US, tick-borne encephalitis Tick-borne encephalitis Arbovirus (arthropod-borne virus) applies to any virus that is transmitted to humans and/or other vertebrates by certain species of blood-feeding arthropods, chiefly insects (flies and mosquitoes)... read more is caused mainly by Powassan virus, a flavivirus that is antigenically related to West Nile West Nile Virus West Nile virus is a flavivirus that is now the primary cause of arbovirus encephalitis in the US. Most patients have mild or no symptoms. About 1 out of 150 patients develop a severe infection... read more , St. Louis encephalitis, and tick-borne encephalitis viruses. Powassan virus infections have been reported primarily in the northeastern states and the Great Lakes region. Powassan virus infections in humans have also been reported in southeastern Canada and Russia (southeastern Siberia, northeast of Vladivostok).

In the US, there are 2 types of Powassan virus, both linked to human disease:

Lineage 2 Powassan virus infection is more likely than lineage 1 infection because I. cookei ticks rarely bite people.

Although rare, Powassan virus encephalitis appears to be increasing since 2009. A total of 181 cases of Powassan virus disease infection have been reported in the US from 2009 to 2019, ranging from 6 to 39 cases per year; most (166) were neurologic disease, resulting in 21 deaths. Cases occur in the late spring to mid-fall, when ticks are most active (4 Arbovirus references Arbovirus (arthropod-borne virus) applies to any virus that is transmitted to humans and/or other vertebrates by certain species of blood-feeding arthropods, chiefly insects (flies and mosquitoes)... read more ).

In the reported cases of Powassan virus infection, neurologic sequelae were common, and the case-fatality rate was high (up to 10 to 15%). This high morbidity and mortality may result from reporting bias because seropositivity in endemic regions is known to be much more common than reported cases, suggesting that there are higher rates of asymptomatic infection.

Powassan virus infection should be considered in patients with encephalitis Encephalitis Encephalitis is inflammation of the parenchyma of the brain, resulting from direct viral invasion. Acute disseminated encephalomyelitis is brain and spinal cord inflammation caused by a hypersensitivity... read more , especially when the patient has a history of tick bite or spends a lot of time outdoors and lives in or has recently traveled to an endemic area. Diagnosis is similar to that of tick-borne encephalitis, with serologic tests to detect Powassan virus–specific IgM antibody in serum or cerebrospinal fluid and confirmed by neutralizing antibody testing of acute- and convalescent-phase serum specimens at a state public health laboratory or the CDC.

There is no vaccine for Powassan virus infection; the vaccine for tick-borne encephalitis available outside the US is directed against different flaviviruses and, when one of these tick-borne encephalitis vaccines was tested in mice, it did not prove to be protective against Powassan virus.

Other tick-borne viruses

Other tick-borne viruses in the US are

California encephalitis serogroup viruses

The California encephalitis serogroup viruses, including California encephalitis virus, La Crosse virus, and Jamestown Canyon virus, belong to the Bunyaviridae family. These viruses are transmitted and maintained by Aedes mosquitoes and occur in the Rocky Mountains, eastern US, southeast Canada, and western Europe.

California encephalitis serogroup viruses cause symptoms (eg, fever, somnolence, obtundation, focal neurologic findings, seizures) primarily in children except for Jamestown Canyon virus, which may also affect adults. Temporal lobe involvement may mimic herpes encephalitis; 20% of patients develop behavioral problems or recurrent seizures.

No treatment is available.

Omsk hemorrhagic fever and Kyasanur Forest disease

Omsk hemorrhagic fever and Kyasanur Forest disease are transmitted by ticks or by direct contact with an infected animal (eg, rodent, monkey). Omsk hemorrhagic fever is caused by a flavivirus; it occurs in Russia, including Siberia. Kyasanur Forest disease, also caused by a flavivirus, occurs in India.

Omsk hemorrhagic fever and Kyasanur Forest disease are acute febrile illnesses accompanied by bleeding diathesis, low blood pressure, leukopenia, and thrombocytopenia; some patients develop encephalitis in the 3rd week. The case fatality rate is < 3% for Omsk hemorrhagic fever and 3 to 5% for Kyasanur Forest disease (6 Arbovirus references Arbovirus (arthropod-borne virus) applies to any virus that is transmitted to humans and/or other vertebrates by certain species of blood-feeding arthropods, chiefly insects (flies and mosquitoes)... read more , 7 Arbovirus references Arbovirus (arthropod-borne virus) applies to any virus that is transmitted to humans and/or other vertebrates by certain species of blood-feeding arthropods, chiefly insects (flies and mosquitoes)... read more ).

Rift Valley fever

Rift Valley fever, caused by a phlebovirus, is spread by mosquitoes and can be transmitted by the following

  • Direct or indirect contact with the blood or organs of infected animals (eg, during slaughtering, butchering, or veterinary procedures)

  • Inhalation of infected aerosols

  • Ingestion of raw milk from infected animal

Eggs from virus-infected Aedes mosquitoes can contain the virus. Those infected eggs can persist for months to years and, when flooded, can hatch and produce infected adult female mosquitoes capable of transmission.

Rarely, Rift Valley fever progresses to ocular disorders, meningoencephalitis, or a hemorrhagic form (which has a 50% case fatality rate). Extensive clusters of abortions may develop in livestock before human cases appear.

A vaccine for livestock is available, and a human vaccine is under investigation.

Arbovirus references

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