The Bunyaviridae are a very large family of single-strand, enveloped RNA viruses that consist of more than 300 viruses that are commonly found and transmitted through rodents (rodent-borne viruses also called roboviruses) and arthropods such as mosquitoes, fleas, ticks, and sandflies (arthropod-borne viruses also called arboviruses). There are five general types of these viruses which include orthobunyavirus, phlebovirus, nairovirus, hantavirus, tospovirus. These viruses can infect humans causing mild to severe diseases. They can also infect plants and animals. Initially, the gut of the arthropod is infected and after a few days or weeks, the virus appears in the saliva. When these arthropods bite a human or other vertebrae host, this infective saliva enters the small capillaries or lymphatics. When the viruses infect humans and other vertebrates, they replicate in the cytoplasm by transcribing their RNA genome into the messenger RNA (mRNA) which is a single-stranded RNA that is complementary to one of the DNA strands of the genes and corresponds to the genetic sequence of that gene and is read by the ribosome in the process of producing proteins.

The distribution of the disease is determined through the host distribution wherein except for the hantavirus, the biologic transmission is possible through arthropods that are infected for life and in which transovarial transmission is common. To maintain the life cycle of the virus, vertebrates are needed with humans usually considered dead-end hosts except for phleboviruses. For the hantavirus, it can be transmitted through infected rodent urine and human infection is incidental.


Infections of the Bunyavirus causes diseases such as:

  • La Crosse Encephalitis. It is considered as the most serious Bunyavirus infection in the United States which was first recognized from a fatal case in La Crosse, Wisconsin, in 1960 and since then,there were at least 1,000 reported cases. Exposure in the woods such as camping activities is a common factor of contracting La Crosse Encephalitis.
    • Type: Orthobunyavirus
    • Vector: Woodland mosquito Aedes triseriatus
    • Hosts: Humans, chipmunks, squirrels
    • Symptoms: Classical acute encephalitis in children
    • Symptoms associated with the central nervous systemcan be accompanied by a stiff neck, lethargy, and seizures.
    • Complications may arise such as epilepsy and persistent paresis
  • Group C and Guama Viruses. It causes a self-limited febrile disease that lasts from 2 to 4 days and commonly occursin Central and South America.
    • Type: Orthobunyavirus
    • Vector: Forest culex (melanoconion) mosquitoes
    • Hosts: Humans, forest rodents, marsupials
    • Symptoms: Dengue-like symptoms such as:
  • Fever
  • Headache
  • Myalgia
  • Nausea
  • weakness
  • Phlebotomus Fever. A condition recognized as febrile illnesses during World War II in troops in the Mediterranean theater and is endemic in North Africa and southern Europe and from the Middle East to Pakistan.
  • Type: Phlebovirus
  • Vector: Sandfly Phlebotomus papatasii
  • Hosts: Humans, forest rodents
  • Symptoms:
    • Fever
    • Headache
    • Muscle pain
    • Joint pain
    • Loss of appetite
    • Nausea
  • Oropouche virus. It causes a major nonfatal febrile disease in Brazil, Trinidad, Peru, and Panama reporting repeated epidemics and tens of thousands of cases.
  • Type: Orthobunyavirus
  • Vector: Midges Culicoides paraennis
  • Hosts: Humans, sloths, monkeys
  • Symptoms:
    • Fever
    • Headache
    • Myalgia
    • Arthralgia
    • Prostration
  • Crimean-Congo Hemorrhagic Fever. It is a severe zoonotic viral disease that was originally recognized in Central Asia and Eastern Europe but is now also found in Bulgaria, Yugoslavia, the former Soviet Union, China, Iraq, United Arab Emirates, Pakistan, and sub-Saharan Africa. Patients with this disease should be isolated since the infection can be transmitted by contaminated blood.
    • Type: Nairovirus
    • Vector: Ticks Hyalomma genus
    • Hosts: Humans, birds, small animals
    • Symptoms: The first symptoms are similar to severe influenza
  • Fever
  • Headache
  • Severe back pain
  • Severe abdominal pain

Hemorrhagic fever symptoms appear after several days which include:

  • Petechial rash
  • Ecchymoses and bruises
  • Hematemesis
  • Melena
  • Rift Valley Fever. It is considered a devastating disease that affects livestock such as sheep, cattle, camels, and goats in Africa. Massive outbreaks of livestock deaths and cow abortions have been recognized in South Africa, Kenya, Uganda, Sudan, Egypt, and Mauritania. The people exposed to this livestock had nonlethal illness however, in 1977, an outbreak in Nile Valley affected thousands of livestock and a large number of humans. The infection was transmitted by aerosolized infected blood and mosquitoes.
    • Type: Phelobovirus
    • Vector: Aedes mosquitoes
    • Hosts: Humans, livestock
    • Symptoms:
  • Fever
  • Severe headache
  • Retroorbital pain
  • Photophobia
  • Myalgia

Complications such as mild encephalitis, retinitis, or hemorrhagic fever may also progress.

  • Hantaviruses. A family of viruses which include the Hantaan virus, Puumala virus, Belgrade Virus, and Seoul virus that mainly spread by rodents causing varied diseases with hemorrhagic fever with renal syndrome (HFRS) being the most common. The first to be recognized is the Hantaan virus which was named after the Hantaan river where the case first occurred among troops deployed in the Korean conflict.
  • Type: Hantavirus
  • Vector:
    • Field mouse Apodemus agrarius in China, Korea, and Russia
    • Field mouse Apodemus flavicollis in the Balkans
    • Bank vole Clethrionomys glareolus in Scandinavia
  • Hosts: Humans, rodents
  • Symptoms:
    • Fever
    • Hemorrhagic complications
    • Acute renal failure with shock


Laboratory tests are performed in the diagnosis of Bunyavirus infections which start by isolating the virus and performing serologic tests such as enzyme-linked immunosorbent assay (ELISA) and complement fixation, fluorescent antibody, neutralization, and hemagglutination inhibition tests.


Vaccinations for Bunyaviruses are available but not all types have vaccines today. Controlling the vectors which are the source of infection is the best way of preventing Bunyavirus infections.

Related Articles


Overview and FactsTypes and SymptomsDiagnosis & MedicationsOverview and Facts Tetralogy of Fallot is a congenital heart defect that affects the [...]


Overview and FactsTypes and SymptomsDiagnosis & MedicationsOverview and Facts Trichinosis, also known as trichinellosis, is a parasitic infection caused by [...]


Overview and FactsTypes and SymptomsDiagnosis & MedicationsOverview and Facts Trigeminal neuralgia is a neurological condition characterized by severe facial pain. [...]