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) and arachnids (ticks). Arbovirus is not part of the current viral classification system, which is based on the nature and structure of the viral genome.
Families in the current classification system that have some arbovirus members include
Most viruses associated with hemorrhagic fevers are classified in the families Arenaviridae and Filoviridae. However, some arboviruses, such as some flaviviruses (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 , 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 viruses) and some Bunyaviridae (Rift Valley fever virus Rift Valley fever 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 , Crimean-Congo hemorrhagic fever virus, severe fever with thrombocytopenia virus, the hantaviruses Hantavirus Infection Bunyaviridae contain the genus Hantavirus, which consists of at least 4 serogroups with 9 viruses causing 2 major, sometimes overlapping, clinical syndromes: Hemorrhagic fever with renal syndrome... read more ), may be associated with hemorrhagic symptoms.
Arbovirus species number > 250 and are distributed worldwide; at least 80 cause human disease. Most arboviruses are transmitted by mosquitoes, but some are transmitted by ticks, and one (Oropouche virus) is transmitted by midges. Birds are often reservoirs for arboviruses, which are transmitted by mosquitoes to horses, other domestic animals, and humans. Other reservoirs for arboviruses include arthropods and vertebrates (often rodents, monkeys, and humans). These viruses may spread to humans from nonhuman reservoirs, but human-to-human transmission may also occur by blood transfusion, organ transplantation, sexual contact, and from mother to child during birth depending on the specific virus involved. Human-to-human transmission of most arboviruses through casual, everyday contact has not been documented. Most arboviral diseases are not transmissible by humans, perhaps because the typical viremia is inadequate to infect the arthropod vector; exceptions include 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 virus infection 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 , and 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 , which can be transmitted from person to person via mosquitoes. Also, Zika virus 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 can be transmitted during sexual activity from infected symptomatic or asymptomatic men to their sex partners (male or female) or from infected women to their sex partner.
Some infections (eg, West Nile virus infection 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 , Colorado tick fever, 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 , Zika virus 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 ) have been spread by blood transfusion or organ donation.
The Arenaviridae includes lymphocytic choriomeningitis virus Lymphocytic Choriomeningitis Lymphocytic choriomeningitis is caused by an arenavirus. It usually causes a flu-like illness or aseptic meningitis, sometimes with rash, arthritis, orchitis, parotitis, or encephalitis. Diagnosis... read more , Lassa fever virus Lassa Fever Lassa fever is an often fatal arenavirus infection that occurs mostly in West Africa. It may involve multiple organ systems. Diagnosis is with serologic tests and polymerase chain reaction ... read more , Mopeia virus, Tacaribe virus, Junin virus, Lujo virus, and Machupo virus; all are transmitted by rodents and thus are not arboviruses. Lassa fever virus Lassa Fever Lassa fever is an often fatal arenavirus infection that occurs mostly in West Africa. It may involve multiple organ systems. Diagnosis is with serologic tests and polymerase chain reaction ... read more can be transmitted from person to person.
The Filoviridae consists of 2 genera: Ebolavirus (consisting of 5 species) and Marburgvirus (consisting of 2 species). The specific vectors of these viruses have not been confirmed, but fruit bats are the prime candidates; thus, Filoviridae are not arboviruses. Human-to-human transmission of Ebola virus and Marburg virus Marburg and Ebola Virus Infections Marburg and Ebola are filoviruses that cause hemorrhage, multiple organ failure, and high mortality rates. Diagnosis is with enzyme-linked immunosorbent assay, polymerase chain reaction (PCR)... read more occurs readily.
Many of these infections are asymptomatic. When symptomatic, they generally begin with a minor nonspecific flu-like illness that may evolve to one of a few syndromes (see table Arbovirus, Arenavirus, and Filovirus Diseases ). These syndromes include lymphadenopathy, rashes, aseptic meningitis Viral Meningitis Viral meningitis tends to be less severe than acute bacterial meningitis. Findings include headache, fever, and nuchal rigidity. Diagnosis is by cerebrospinal fluid (CSF) analysis. Treatment... read more , 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 , arthralgias, arthritis, and noncardiogenic pulmonary edema. Many cause fever and bleeding tendencies (hemorrhagic fever). Decreased synthesis of vitamin K–dependent coagulation factors, disseminated intravascular coagulation Disseminated Intravascular Coagulation (DIC) Disseminated intravascular coagulation (DIC) involves abnormal, excessive generation of thrombin and fibrin in the circulating blood. During the process, increased platelet aggregation and coagulation... read more , and altered platelet function contribute to bleeding.
Laboratory diagnosis often involves viral cultures, polymerase chain reaction, electron microscopy, and antigen and antibody detection methods where available.
Treatment
Treatment for most of these infections is supportive.
In hemorrhagic fevers, bleeding may require phytonadione (vitamin K1 Vitamin K Deficiency Vitamin K deficiency results from extremely inadequate intake, fat malabsorption, or use of coumarin anticoagulants. Deficiency is particularly common among breastfed infants. It impairs clotting... read more ). Transfusion of packed red blood cells or fresh frozen plasma may also be necessary. Aspirin and other NSAIDs (nonsteroidal anti-inflammatory drugs) are contraindicated because of antiplatelet activity. For advanced cases of hantavirus cardiopulmonary syndrome, extracorporeal membrane oxygenation (ECMO) may be needed.
The following is recommended for hemorrhagic fever caused by arenaviruses or bunyaviruses including Lassa fever Lassa Fever Lassa fever is an often fatal arenavirus infection that occurs mostly in West Africa. It may involve multiple organ systems. Diagnosis is with serologic tests and polymerase chain reaction ... read more , Rift Valley fever Rift Valley fever 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 , and Crimean-Congo hemorrhagic fever:
Treatment of hemorrhagic fever with renal syndrome Treatment Bunyaviridae contain the genus Hantavirus, which consists of at least 4 serogroups with 9 viruses causing 2 major, sometimes overlapping, clinical syndromes: Hemorrhagic fever with renal syndrome... read more is with IV ribavirin: loading dose 33 mg/kg (maximum, 2.64 g), followed by 16 mg/kg every 6 hours (maximum, 1.28 g every 6 hours) for 4 days, then 8 mg/kg every 8 hours (maximum, 0.64 g every 8 hours) for 3 days.
Antiviral treatment for other syndromes has not been adequately studied. Ribavirin has not been effective in animal models of filovirus and flavivirus infections. The US Food and Drug Administration (FDA) approved 2 drugs to treat Ebola virus disease caused by Zaire Ebola virus in adults and children: a combination of three monoclonal antibodies (atoltivimab/maftivimab/odesivimab) and a single monoclonal antibody (ansuvimab).
Prevention
The abundance and diversity of arboviruses means that it is often easier and cheaper to control arbovirus infections by destroying their arthropod vectors, preventing bites, and eliminating their breeding habitats than by developing specific vaccines or drug treatments.
Vector control and bite prevention
Diseases transmitted by mosquitoes or ticks can often be prevented by the following:
-
Wearing clothing that covers as much of the body as possible
-
Using insect repellants (eg, DEET [diethyltoluamide])
-
Minimizing the likelihood of exposure to the insect or tick (eg, for mosquitoes, limiting time outdoors in wet areas; for ticks, see sidebar Tick Bite Prevention Tick Bite Prevention Lyme disease is a tick-transmitted infection caused by the spirochete Borrelia species. Early symptoms include an erythema migrans rash, which may be followed weeks to months later by neurologic... read more
) -
There has been recent progress in reducing populations of Aedes aegypti through the release of sterile males or genetically modified males. Also, field trials are underway with introduction into the wild of Aedes aegypti mosquitoes that have been infected with Wolbachia bacteria. These bacteria do not reduce mosquito populations. Instead, they block infection of the mosquitoes by dengue, chikungunya, and Zika viruses, thus reducing transmission of disease. The Wolbachia are transmitted to the infected mosquito's offspring, thus multiplying the effectiveness of the technique.
Diseases transmitted by rodent excreta can be prevented by the following:
-
Before cleaning, ventilate for ≥ 15 minutes closed spaces where mice have been.
-
Wet down surfaces with a 10% bleach solution before sweeping or cleaning.
-
Avoid stirring up dust.
-
Seal sites of potential rodent entry into homes and nearby buildings.
-
Prevent rodent access to food.
-
Eliminate potential nesting sites in and around the home and other buildings.
Guidelines for cleaning up after rodents and working in areas with potential rodent excreta are available from the Centers for Disease Control and Prevention (CDC).
Because transmission of the filoviruses Ebola virus and Marburg virus Marburg and Ebola Virus Infections Marburg and Ebola are filoviruses that cause hemorrhage, multiple organ failure, and high mortality rates. Diagnosis is with enzyme-linked immunosorbent assay, polymerase chain reaction (PCR)... read more is predominantly from person to person, prevention of spread requires strict quarantine and isolation measures.
Vaccination
At present, in the US there are effective vaccines only for Ebola virus Marburg and Ebola Virus Infections Marburg and Ebola are filoviruses that cause hemorrhage, multiple organ failure, and high mortality rates. Diagnosis is with enzyme-linked immunosorbent assay, polymerase chain reaction (PCR)... read more , yellow fever virus Prevention 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 and Japanese encephalitis virus. Vaccines for 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 are available in Europe, Russia and China. A vaccine for dengue Prevention 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 is approved in several countries outside the US, but efficacy is only moderate and varies by dengue immune status, serotype, and patient age; studies are ongoing.
