Venezuelan haemorrhagic fever

Venezuelan hemorrhagic fever (VHF) is caused by the Guanarito virus. Guanarito virus belongs to the family Arenoviridae (arenoviruses) and was identified as the causative agent of VHF in 1989. This virus occurs mainly in the area around Guanarito, a municipality in the state of Portugal, and in parts of the state of Barinas in Venezuela.

The main host for the Guanarito virus is the sugar cane rat (Zygodontomys brevicauda). Like the cotton rat (Sigmodon alstoni), which may also be infected with the guanarito virus, the sugarcane rat lives in the Venezuelan grasslands. In the years 1989 to 1997, 220 cases of VHF were described.

Pathophysiologically, generalized multi-organ infection occurs after initial multiplication of the viruses at the point of entry. Especially lymph nodes, lungs and later other organs are important sites of virus replication. The virus preferentially infects cells of the immune system and thus appears to increase vascular permeability by releasing cytokines and disrupt the defence reaction. The increased vascular permeability leads to the loss of blood proteins and fluid. A state of shock can occur.

The neurological symptoms are possibly caused by the deposition of immune complexes in the brain vessels.

Note: The Junin, Machupo, Guanarito and Sabia viruses belong to the New World family of Arena viruses and are found in South America. These arena viruses are the cause of various hemorrhagic fever diseases such as:

• Venezuelan Hemorrhagic Fever (VHF)
• Argentine hemorrhagic fever (AHF)
• Bolivian hemorrhagic fever
• Brazilian haemorrhagic fever (BHF)

The name arena virus is derived from a characteristic dark granulation (Latin arenosus = sandy) of the viruses in electron microscopic images. These are shown as ribosomes, which are included in the sprouting of the viruses.

The arena viruses consist of a lipid shell and are pleomorphic with an average diameter of 50-300nm. They contain 2 RNA segments, the L- du the S-segment, which contain the information for structural proteins (nucleocapsid protein and glycoproteins) and an enzyme (viral polymerase). In the finished virus, the nucleocapsid is stored protectively around the RNA. The glycoproteins G1 and G2 are anchored in the lipid envelope. They serve for the absorption and release of the L and S segments into the cytoplasm and are thus essential for recognition and penetration into the host cell. The reproduction of the viruses in the cell takes place via a viral polymerase.

In VHF, the symptoms are similar to those of Argentine hemorrhagic fever (AHF) and Bolivian hemorrhagic fever. Initially, in addition to the general symptoms such as fever, malaise, headache, bleeding gums and pain in the limbs, a sore throat typically occurs.

Petechiae in the skin or mucous membranes are less common than in AHF and BHF. Hemorrhagic bleeding and neurological manifestations in the second phase are responsible for the high mortality rate of 33%.

/en/internal-medicine/favipiravir-142505.amp" title="FavipiravirTheinfections with the South American hemorrhagic fever viruses are mainly treated symptomatically. In many patients a light sedation (sedation) and pain treatment with opiates is useful. Bleeding should be treated by transfusions of platelets and coagulation factors.

Control of the electrolyte and fluid balance, if necessary controlled balancing.

In individual cases, infusions of immunoplasmas (plasma from convalescent patients) have been therapeutically successful.

A commercial immunoglobulin does not yet exist.

The antiviral drug ribavirin seems to have a positive influence on the outcome of Junin and Machupo virus infections at least.

Animal experiments with the viral drug favipiravir have been successful in the treatment of arena virus infections (Gowen BB et al. 2017; Furuta Y et al. 2013), so that it can be assumed that this drug is also used in humans (see Favipiravir).

1. Golden JW et al (2017) An attenuated Machupo virus with a disrupted L-segment intergenic region protects Guinea pigs against lethal Guanarito virus infection. Sci Rep 7:4679.
2. Gowen BB et al (2017) Enhanced protection against experimental Junin virus infection through the use of a modified favipiravir loading dose strategy. Antiviral Res 145:131-135.
3. Tani H et al (2018) Arenavirus research and antiviral candidate. Uirusu 68:51-62.
4. Furuta Y et al (2013) Favipiravir (T-705), a novel viral RNA polymerase inhibitor. Antiviral Res 100:446-454.