Types and Varieties of Viruses: Current Threats and Diagnostic Methods
Virus Classification
Viruses are non-cellular infectious agents that affect all forms of life, from plants and animals to bacteria and archaea. They are classified based on various criteria:
- By nucleic acid type: DNA-containing and RNA-containing viruses.
- By capsid shape: Helical, icosahedral, and complex viruses.
- By transmission method: Airborne, contact, fecal-oral, vector-borne (through insect bites).
Current Viral Threats
- Respiratory Viruses:
- Human Metapneumovirus (hMPV): In January 2025, an outbreak of metapneumovirus was reported in China, causing flu-like and COVID-19-like symptoms. Symptoms include cough, nasal congestion, fever, shortness of breath, and hoarseness. Children under five and the elderly are particularly vulnerable. In Russia, hMPV accounts for about 0.1% of acute respiratory viral infections (ARVI).
- Coronaviruses (SARS-CoV-2): Although the COVID-19 pandemic has subsided, the virus continues to circulate, causing localized outbreaks. Symptoms include fever, cough, loss of smell and taste, and fatigue.
- Hepatotropic Viruses:
- Hepatitis B Virus (HBV): Transmitted through blood and other bodily fluids, it can cause chronic liver disease.
- Hepatitis C Virus (HCV): Often leads to chronic infections and is primarily spread through blood contact.
- Sexually Transmitted Viruses:
- Human Papillomavirus (HPV): Some strains are linked to cervical cancer and other oncological diseases.
- Herpes Simplex Virus (HSV): Causes genital and oral herpes, characterized by periodic outbreaks.
- Herpesviruses:
- Epstein-Barr Virus (EBV): Associated with infectious mononucleosis and some types of lymphoma.
- Cytomegalovirus (CMV): Can cause severe complications in immunocompromised individuals.
Methods for Diagnosing Viral Infections
- Molecular Methods:
- Polymerase Chain Reaction (PCR): Detects and identifies viral genetic material with high accuracy.
- Reverse Transcription PCR (RT-PCR): Used for RNA-containing viruses, such as SARS-CoV-2.
- Serological Methods:
- Enzyme-Linked Immunosorbent Assay (ELISA): Identifies the presence of antibodies or viral antigens in the blood, indicating a current or past infection.
- Neutralization Test: Assesses the ability of antibodies to neutralize the virus, useful for evaluating immune response.
- Virological Methods:
- Virus Cultivation: Growing the virus in cell cultures for further study.
- Electron Microscopy: Allows visualization of viral particles, determining their morphology.
Statistics and Projections
- ARVI and Influenza: In January 2025, Russia recorded a 30% increase in ARVI cases, with 573,000 reported cases across 49 regions.
- Hepatitis B and C: According to the World Health Organization, over 296 million people worldwide live with chronic hepatitis B infection, and about 58 million with hepatitis C.
- HPV: Around 85% of sexually active women and 90% of men contract HPV during their lifetime. More than 300,000 deaths occur annually due to HPV-related cancers.
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Understanding the diversity of viruses and their diagnostic methods is key to effectively controlling and preventing infectious diseases. Regular medical check-ups and timely vaccinations help reduce the risk of infection and the spread of viral diseases.