Hantavirus: Molecular diagnosis (RT-PCR).

Hantaviruses are viruses of the family Bunyaviridae, genus Hantavirus. They are single-stranded (ss(-) RNA viruses whose genome is divided into three segments: L (Large), which encodes the RNA polymerase or L protein; M (Medium), which encodes the G1 and G2 proteins; and S (Small), which encodes the nucleocapsid (N).

These viruses are transmitted by rodents (family Muridae) in various regions of Asia, Europe, and North America. Infection occurs through aerosols generated from the feces, urine, and saliva of infected rodents. It constitutes a public health problem in many countries.

Several different serotypes are associated with the disease. The severity of the illness depends on the specific serotype.

• Hantaan (HTN) – transmitted by Apodemus agrarius.
• Seoul (SEO) – transmitted by Rattus norvegicus.
• Dobrova (DOB) – transmitted by Apodemus agrarius and Apodemus flavicollis in the Balkans.
• Puumala (PUU) – transmitted by Clethrionomys glareolus.
• Prospect Hill (PH) – transmitted by Peromyscus manimaculatus (not associated with disease).
• Sin Nombre (SN; = Four Corner virus because it was found in a border area between four US states) – transmitted by Peromyscus manimaculatus – the deer mouse – in the southwestern US.
• Other viruses related to SN include:

-        New York virus (NYV)

-        Bayou virus (BAYV)

-        Black Creek Canal virus (BCCV)

The SN (Sin Nombre) and NYV viruses cause a severe pulmonary syndrome called HPS (Hantavirus Pulmonary Syndrome). The BAYV (Bayou virus) and BCCV (Black Creek Canal virus) viruses produce a pulmonary syndrome with renal failure.

Hantavirus pulmonary syndrome is characterized by fever, myalgia, vascular loss syndrome with hemoconcentration, thrombocytopenia, and pulmonary edema.

Hemorrhagic fever with renal syndrome (HFRS) is characterized by fever, flank pain, thrombocytopenia, elevated liver enzymes, and transient renal failure. The most severe forms are caused by serotypes found in Asia, China, and eastern Russia, but severe cases have also been reported in some parts of Europe.

There are some similarities and differences between the two syndromes. HFRS is an acute interstitial nephritis that causes azotemia and proteinuria. This is rare in HPS. Both syndromes involve fever, myalgia, thrombocytopenia, hypotension, and shock. Shock is related to vascular fluid loss, which causes the extravasation of proteinaceous fluid from the capillaries into the pulmonary interstitium in pulmonary hypertension (PHS) or into the retroperitoneal space in respiratory failure with HFRS.

There is a more severe variant of HFRS in Asia (caused by HTN virus) and in the Balkans (caused by DOB virus), and a milder variant caused by PUU and SEO virus that occurs in Northern Europe.