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Aside from formal systems of nomenclature, viruses are often informally grouped into categories based on chemistry, morphology, or other characteristics they share in common. Categories may include naked or enveloped structure, single-stranded (ss) or double-stranded (ds) DNA or ss or ds RNA genomes, segmented or nonsegmented genomes, and positive-strand (+) or negative-strand (−) RNA. For example, herpes viruses can be classified as a dsDNA enveloped virus; human immunodeficiency virus (HIV) is a +ssRNA enveloped virus, and tobacco mosaic virus is a +ssRNA virus. Other characteristics such as host specificity, tissue specificity, capsid shape, and special genes or enzymes may also be used to describe groups of similar viruses. [link] lists some of the most common viruses that are human pathogens by genome type.

Common Pathogenic Viruses
Genome Family Example Virus Clinical Features
dsDNA, enveloped Poxviridae Orthopoxvirus Skin papules, pustules, lesions
Poxviridae Parapoxvirus Skin lesions
Herpesviridae Simplexvirus Cold sores, genital herpes, sexually transmitted disease
dsDNA, naked Adenoviridae Atadenovirus Respiratory infection (common cold)
Papillomaviridae Papillomavirus Genital warts, cervical, vulvar, or vaginal cancer
Reoviridae Reovirus Gastroenteritis severe diarrhea (stomach flu)
ssDNA, naked Parvoviridae Adeno-associated dependoparvovirus A Respiratory tract infection
Parvoviridae Adeno-associated dependoparvovirus B Respiratory tract infection
dsRNA, naked Reoviridae Rotavirus Gastroenteritis
+ssRNA, naked Picornaviridae Enterovirus C Poliomyelitis
Picornaviridae Rhinovirus Upper respiratory tract infection (common cold)
Picornaviridae Hepatovirus Hepatitis
+ssRNA, enveloped Togaviridae Alphavirus Encephalitis, hemorrhagic fever
Togaviridae Rubivirus Rubella
Retroviridae Lentivirus Acquired immune deficiency syndrome (AIDS)
−ssRNA, enveloped Filoviridae Zaire Ebolavirus Hemorrhagic fever
Orthomyxoviridae Influenzavirus A, B, C Flu
Rhabdoviridae Lyssavirus Rabies
  • What are the types of virus genomes?

Classification of viral diseases

While the ICTV has been tasked with the biological classification of viruses, it has also played an important role in the classification of diseases caused by viruses. To facilitate the tracking of virus-related human diseases, the ICTV has created classifications that link to the International Classification of Diseases (ICD) , the standard taxonomy of disease that is maintained and updated by the World Health Organization (WHO). The ICD assigns an alphanumeric code of up to six characters to every type of viral infection, as well as all other types of diseases, medical conditions, and causes of death. This ICD code is used in conjunction with two other coding systems (the Current Procedural Terminology, and the Healthcare Common Procedure Coding System) to categorize patient conditions for treatment and insurance reimbursement.

For example, when a patient seeks treatment for a viral infection, ICD codes are routinely used by clinicians to order laboratory tests and prescribe treatments specific to the virus suspected of causing the illness. This ICD code is then used by medical laboratories to identify tests that must be performed to confirm the diagnosis. The ICD code is used by the health-care management system to verify that all treatments and laboratory work performed are appropriate for the given virus. Medical coders use ICD codes to assign the proper code for procedures performed, and medical billers, in turn, use this information to process claims for reimbursement by insurance companies. Vital-records keepers use ICD codes to record cause of death on death certificates, and epidemiologists used ICD codes to calculate morbidity and mortality statistics.

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Source:  OpenStax, Microbiology. OpenStax CNX. Nov 01, 2016 Download for free at http://cnx.org/content/col12087/1.4
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