Introduction
Table of Contents
Hantaviruses are a group of rodent-borne viruses that cause two main life-threatening diseases in humans: Hantavirus Pulmonary Syndrome (HPS) and Hemorrhagic Fever with Renal Syndrome (HFRS). Unlike many other bunyaviruses, they are not transmitted by insects but primarily through the inhalation of aerosolized rodent excreta.
- Taxonomy: They belong to the family Hantaviridae and the order Bunyavirales.
- Geographic Split:
- Old World Hantaviruses: Found in Europe and Asia, causing HFRS (e.g., Hantaan and Seoul viruses).
- New World Hantaviruses: Found in the Americas, causing HPS (e.g., Sin Nombre and Andes viruses).
- Impact: Approximately 150,000 to 200,000 cases occur annually, with high mortality rates reaching 40–50% for HPS.
Morphology
- Structure: Enveloped, spherical to pleomorphic particles (80–210 nm in diameter) with characteristic square, grid-like surface projections.
- Genome: Tripartite, single-stranded, negative-sense RNA consisting of three segments:
- L (Large): Encodes the RNA-dependent RNA polymerase (RdRp).
- M (Medium): Encodes two surface glycoproteins, Gn and Gc.
- S (Small): Encodes the nucleocapsid (N) protein.
- Internal Symmetry: The ribonucleocapsid shows helical symmetry.
Pathogenicity
- Primary Target: Vascular endothelial cells (specifically in lungs and kidneys) and macrophages.
- Mechanism: Pathogenic strains use beta-3-integrin receptors for cell entry. Infection causes a “cytokine storm” (e.g., high TNF-alpha, IL-6) leading to:
- Vascular Leakage: The hallmark of both syndromes is caused by increased capillary permeability.
- Thrombocytopenia: Low platelet counts are common in acute stages.
- HFRS Phases: Febrile, Hypotensive, Oliguric, Polyuric, and Convalescent.
- HPS Phases: Prodromal, Cardiopulmonary (rapid pulmonary edema and shock), and Convalescent.
Lab Diagnosis
- Serology (Gold Standard): Detection of IgM antibodies (indicating acute infection) or a four-fold rise in IgG titers using ELISA or Immunoblot.
- Molecular: RT-PCR to detect viral RNA in blood or tissue samples during the early viremic phase.
- Hematology: CBC typically shows thrombocytopenia, leukocytosis (in HPS), and hemoconcentration.
- Culture: Technically difficult; requires Biosafety Level 3 (BSL-3) facilities.
Treatment and Prevention
- Treatment: No specific FDA-approved antiviral exists. Management is primarily supportive.
- HFRS: Hydration, electrolyte management, and dialysis for renal failure. Ribavirin may be effective if started very early.
- HPS: Intensive care (ICU), oxygen therapy, mechanical ventilation, or ECMO in severe cases.
- Prevention:
- Rodent Control: Seal holes, use traps, and eliminate food sources.
- Safe Cleaning: Do not vacuum or sweep dry rodent droppings. Use a 10% bleach solution to wet down areas before cleaning with gloves.
Keynotes
- Andes Virus: The only hantavirus confirmed to allow human-to-human transmission.
- Stability: Hantaviruses are susceptible to detergents, UV radiation, and heat (60°C for 30 min).
- Infectious Dose: The virus is highly infectious via inhalation, making it a significant occupational risk for agricultural and military personnel.
Further Readings
- https://pmc.ncbi.nlm.nih.gov/articles/PMC10601933/
- https://www.sciencedirect.com/topics/medicine-and-dentistry/hantavirus
- https://pmc.ncbi.nlm.nih.gov/articles/PMC6783877/
- https://www.sciencedirect.com/topics/medicine-and-dentistry/hantavirus
- https://www.cdc.gov/hantavirus/hcp/clinical-overview/hps.html
- https://www.canada.ca/en/public-health/services/diseases/hantaviruses/health-professionals-treating-hantavirus-infection.html
- https://www.who.int/emergencies/disease-outbreak-news/item/2026-DON599
- https://pmc.ncbi.nlm.nih.gov/articles/PMC4661284/
- https://pubmed.ncbi.nlm.nih.gov/10073292/
- https://www.clinicalmicrobiologyandinfection.org/article/S1198-743X(14)64767-4/fulltext
- https://www.cdc.gov/hantavirus/hcp/clinical-overview/hfrs.html
- https://pmc.ncbi.nlm.nih.gov/articles/PMC2880890/