Hantaviruses

Key Features

Essentials of Diagnosis

• Transmitted by rodents and cause two clinical syndromes

• Hemorrhagic fever with renal syndrome (HFRS): mild to severe illness

• Hantavirus pulmonary syndrome (HPS): 40% mortality rate

General Considerations

• Hantaviruses are enveloped RNA bunyaviruses; hosts are rodents, moles, and shrews

• Hantavirus infection in humans can cause several disease syndromes

• HFRS is caused by viruses called Old World hantaviruses (in Asia and Europe)

  • Dobrava-Belgrade virus

  • Puumala virus

  • Seoul virus and Hantaan virus

• Nephropathia epidemica is a milder form of HFRS; Puumala virus is the most prevalent pathogen and is present throughout Europe

• HPS, also known as hantavirus cardiopulmonary syndrome, is caused byviruses called New World Hantaviruses (in the Americas), primarily Sin Nombre virus and Andes virus

• A specific strain is not associated with a specific syndrome and overlap is seen between the syndromes

• Aerosols of virus-contaminated rodent urine and feces are thought to be the main vehicle for transmission to humans

• Person-to-person transmission is observed only with the Andes virus

• Occupation at highest risk for transmission of all hantaviruses include

  • Animal trappers

  • Forestry workers

  • Laboratory personnel

  • Farmers

  • Military personnel

Demographics

• A total of 728 cases of hantavirus infection have been reported in the United States since 1993

• Average case fatality rate is 36%

• Most cases reported from states west of the Mississippi River

• Outbreaks of HPS associated with other hantavirus types are also reported in Central and South America and the Caribbean

Clinical Findings

Symptoms and Signs

• Vascular leakage is the hallmark of disease for both syndromes

  • Kidneys are main target with variants associated with HFRS

  • Lungs are the main target with variants associated with HPS

• HFRS manifests as mild, moderate, or severe illness depending on the causative strain

  • A 2- to 3-week incubation period is followed by a protracted clinical course, typically consisting of five distinct phases

    • Febrile period

    • Hypotension

    • Oliguria

    • Diuresis

    • Convalescence phase

  • Varying degrees of renal involvement are seen, occasionally frank hemorrhage

  • Disseminated intravascular coagulation (DIC) and thromboembolic phenomena are recognized complications

  • Pulmonary edema is not typically seen but when present usually occurs in the final stages of disease (oliguric and diuretic phase)

  • Encephalitis and pituitary involvement are rare, although cases are reported with Puumala virus

  • Patients may have persistent hematuria, proteinuria, or hypertension up to 35 months after infection

  • Smoking appears to exacerbate the viremia with the Puumula variant of HFRS

• Clinical course of HPS is divided into a febrile prodrome, a cardiopulmonary stage, oliguric and diuretic phase followed by convalescence

  • A 14- to 17-day incubation period is followed by a prodromal phase

    • Typically lasts 3–6 days

    • Associated with myalgia, malaise, abdominal pain along with nausea, vomiting, and diarrhea, headache, chills, and fever of abrupt onset

  • Cardiopulmonary phase ...