Hantavirus
Hantaviruses belong to the genus Hantavirus within the Bunyaviridae family. The medium-sized single-stranded negative-sense RNA genome consists of three unique segments: large (L) that codes for virus polymerase, medium (m) that codes for glycoproteins G1 and G2 and small (S) that codes for the nucleocapsid. There are at least three groups of hantavirus that have been connected with disease. Each of these virus groups is associated with specific rodent hosts: Hantaan-like virus with Apodemus spp., Seoul-like virus with Rattus spp. and Puumala-like virus with Clethrionymus glareolus. The virus implicated in most cases of HPS in the USA has been named Sin Nombre and is
associated with Peromyscus maniculatus. However, in other areas of the Americas, different Sigmodontinae rodent reservoirs are important. The Sin Nombre-like viruses seems to be more related to Prospect Hill virus, which was isolated from Microtus pennsylvanicus in the USA. However, the Prospect Hill virus has not been associated with any human disease.
Hantaviruses (genus Hantavirus, family Bunyaviridae) are the causative agents of viral haemorrhagic fevers:
- Haemorrhagic fever with renal syndrome (HFRS):
- occurs primarily in Eastern Asia and the Balkans.
- Nephropathia epidemica (NE), is seen in the northwestern parts of Eurasia, especially in Scandinavia.
- The hantavirus pulmonary syndrome (HPS) was first described in the southwestern USA but more recently has also been reported in other parts of the Americas.
Transmission:
Incubation:
- 1-6 weeks.
Clinical Features:
for HPS:
- Systemic: Acute High Fever, Myalgia, Headache
- Respiratory: Cough, Acute Respiratory Distress
- Others: Nausea, Vomiting, Gastrointestinal Distress
Both HFRS and HPS start with influenza-like symptoms (acute high fever and myalgia). After 2–5 days patients develop haemorrhagic manifestations and/or renal symptoms. In milder cases of HFRS there may be few overt renal symptoms but signs of liver involvement may be present. Pulmonary symptoms dominate in HPS and the disease can progress very rapidly to fatal respiratory failure.
Complications:
HFRS: Kidney failure is often observed with transitory reduced glomerular filtration rate that may persist for months after the acute phase of the disease.
Laboratory Diagnosis:
Attempts to isolate the virus from clinical specimens are rarely successful. For HFRS and NE serological diagnosis is based on the detection of IgM antibodies in acute phase serum or IgG titre rise in paired sera using indirect immunofluorescence. The disease progression in HPS is often so rapid that a virus-specific antibody response may not be detectable in the early acute phase of the disease. PCR tests for hantavirus RNA have been used successfully to confirm the presence of virus in tissue samples.
Treatment & Prophylaxis:
The treatment in HFRS (NE) is symptomatic. Renal dialysis and support of homeostasis (fluid and electrolyte balance) are important. In HPS, respiratory and circulatory support, in addition to haemodialysis, may be necessary. The antiviral drug ribavirin may be effective in reducing mortality in severe cases of HFRS, but the effectiveness in treatment of HPS has not been established.
AMH
