Viral disease

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Viral disease
Classification and external resources
MeSH D014777

A viral disease (or viral infection) occurs when an organism's body is invaded by pathogenic viruses. These are tables of the clinically most important[1] viruses. A vast number of viruses cause infectious diseases, but these are the major ones.[2]

Structural characteristics[edit]

Basic structural characteristics, such as genome type, virion shape and replication site, generally share the same features among virus species within the same family. There are currently 21 families of viruses known to cause disease in humans.

There are five double-stranded DNA families: three are non enveloped (Adenoviridae, Papillomaviridae and Polyomaviridae) and two are enveloped (Herpesviridae and Poxviridae). All of the non-enveloped families have icosahedral nucleocapsids.

There is one family of partly double-stranded DNA viruses: Hepadnaviridae. These viruses are enveloped.

There is one family of single-stranded DNA viruses that infect humans: Parvoviridae. These viruses are non-enveloped.

There are seven positive single-stranded RNA families: three non enveloped (Astroviridae, Caliciviridae and Picornaviridae) and four enveloped (Coronoviridae, Flaviviridae, Retroviridae and Togaviridae). All the non-enveloped families have icosahedral nucleocapsids.

There are six negative single-stranded RNA families: Arenaviridae, Bunyaviridae, Filoviridae, Orthomyxoviridae, Paramyxoviridae and Rhabdoviridae. All are enveloped with helical nucleocapsids.

There is one family with a double-stranded RNA genome: Reoviridae.

There is one additional virus (Hepatitis D virus) which has not yet been assigned to a family but is clearly distinct from the other families infecting humans.

There is one family and one genus of viruses known to infect humans that have not been associated with disease: the family Anelloviridae and the genus Dependovirus. Both of these taxa are non-enveloped single-stranded DNA viruses.

Useful rules of thumb[edit]

Among the human infecting families there are a number of rules that may assist physicians and medical microbiologists/virologists.

As a general rule, DNA viruses replicate within the nucleus while RNA viruses replicate within the cytoplasm. Exceptions are known to this rule: Poxviruses (DNA viruses) replicate within the cytoplasm and orthomyxoviruses and hepatitis D virus (RNA viruses) replicate within the nucleus.

Four families have segmented genomes: Bunyaviridae, Orthomyxoviridae, Arenaviridae and Reoviridae (acronym BOAR). All are RNA viruses.

Three families are transmitted almost exclusively by arthropods: Bunyavirus, Flavivirus and Togavirus. Some Reoviruses are transmitted from arthropod vectors as well. All are RNA viruses.[3]

Only one family of enveloped viruses causes gastroenteritis (Coronaviridae). All other viruses associated with gastroenteritis are non enveloped.

Comparison table of clinically important virus families and species
Family Baltimore group Important species[1] envelopment[1] Virion shape[1] Replication site[1]
Adenoviridae Group I Adenovirus non-enveloped icosahedral nucleus
Herpesviridae Group I Herpes simplex, type 1, Herpes simplex, type 2, Varicella-zoster virus, Epstein-barr virus, Human cytomegalovirus, Human herpesvirus, type 8 enveloped complex nucleus
Papillomaviridae Group I Human papillomavirus non-enveloped icosahedral nucleus
Polyomaviridae Group I BK virus, JC virus non-enveloped icosahedral nucleus
Poxviridae Group I Smallpox enveloped complex cytoplasm
Hepadnaviridae Group VII Hepatitis B virus enveloped icosahedral nucleus
Parvoviridae Group II Human bocavirus, Parvovirus B19 non-enveloped icosahedral nucleus
Astroviridae Group IV Human astrovirus non-enveloped icosahedral cytoplasm
Caliciviridae Group IV Norwalk virus non-enveloped icosahedral cytoplasm
Picornaviridae Group IV coxsackievirus, hepatitis A virus, poliovirus, rhinovirus non-enveloped icosahedral cytoplasm
Coronaviridae Group IV Severe acute respiratory syndrome virus enveloped helical cytoplasm
Flaviviridae Group IV Hepatitis C virus, yellow fever virus, dengue virus, West Nile virus enveloped icosahedral cytoplasm
Togaviridae Group IV Rubella virus enveloped icosahedral cytoplasm
Hepeviridae Group IV Hepatitis E virus enveloped icosahedral cytoplasm
Retroviridae Group VI Human immunodeficiency virus (HIV) enveloped icosahedral[4] nucleus
Orthomyxoviridae Group V Influenza virus enveloped helical nucleus[5]
Arenaviridae Group V Guanarito virus, Junin virus, Lassa virus, Machupo virus, Sabiá virus enveloped helical cytoplasm
Bunyaviridae Group V Crimean-Congo hemorrhagic fever virus enveloped helical cytoplasm
Filoviridae Group V Ebola virus, Marburg virus enveloped helical cytoplasm
Paramyxoviridae Group V Measles virus, Mumps virus, Parainfluenza virus, Respiratory syncytial virus, Human metapneumovirus, Hendra virus, Nipah virus enveloped helical cytoplasm
Rhabdoviridae Group V Rabies virus enveloped helical, bullet shaped cytoplasm
Unassigned Group V Hepatitis D enveloped spherical nucleus
Reoviridae Group III Rotavirus, Orbivirus, Coltivirus, Banna virus non-enveloped icosahedral cytoplasm

Clinical characteristics[edit]

The clinical characteristics of viruses may differ substantially among species within the same family:

Type Family Transmission[1] Diseases[1] Treatment[1] Prevention[1] laboratory diagnosis[1]
Adenovirus Adenoviridae
  • droplet contact
  • fecal-oral
  • venereal
  • direct contact (ocular infections)
None
  • vaccine
  • hand washing
  • covering mouth when coughing/sneezing
  • avoiding close contact with the sick
Coxsackievirus Picornaviridae
  • fecal-oral
  • droplet contact
None
  • hand washing
  • covering mouth when coughing/sneezing
  • avoiding contaminated food/water
  • improved sanitation
Cell culture, antibody detection
Epstein-Barr virus Herpesviridae
  • saliva
None
  • avoiding close contact with the sick
Hepatitis A virus Picornaviridae
  • fecal-oral
Immunoglobulin (post-exposure prophylaxis)
  • vaccine
  • avoiding contaminated food/water
  • improved sanitation
antibody detection
Hepatitis B virus Hepadnaviridae
  • vaccine
  • immunoglobulin (perinatal and post-exposure prophylaxis)
  • avoiding shared needles/syringes
  • safe sex
  • viral antigen detection
  • antibody detection
  • nucleic acid detection
Hepatitis C virus Flaviviridae
  • blood
  • sexual contact
  • avoiding shared needles/syringes
  • safe sex
  • antibody detection
  • nucleic acid detection
Herpes simplex virus, type 1 Herpesviridae
  • direct contact
  • saliva
  • avoiding close contact with lesions
  • safe sex
Herpes simplex virus, type 2 Herpesviridae
  • sexual contact
  • vertical transmission
  • avoiding close contact with lesions
  • safe sex
Cytomegalovirus Herpesviridae
  • hand washing
  • avoid sharing food and drinks with others
  • safe sex
antibody and nucleic acid detection
Human herpesvirus, type 8 Herpesviridae
  • bodily fluids
many in evaluation-stage
  • avoid close contact with lesions
  • safe sex
Nucleic acid and antibody detection
HIV Retroviridae HAART
  • zidovudine (perinatally)
  • blood product screening
  • avoiding shared needles/syringes
  • safe sex
  • nucleic acid,
  • p24
  • antibody detection
Influenza virus Orthomyxoviridae
  • droplet contact
  • vaccine
  • hand washing
  • covering mouth when coughing/sneezing
  • avoiding close contact with the sick
Measles virus Paramyxoviridae
  • droplet contact
None
  • vaccine
  • quarantining the sick
  • avoiding contact with the sick
antibody detection
Mumps virus Paramyxoviridae
  • droplet contact
None
  • vaccine
  • avoiding close contact with the sick
antibody detection
Human papillomavirus Papillomaviridae
  • vaccine
  • avoiding close contact with lesions
  • safe sex
  • Visual inspection
  • Antigen detection
  • Nucleic acid detection
Parainfluenza virus Paramyxoviridae
  • droplet contact
None
  • hand washing
  • covering mouth when coughing/sneezing
Antibody detection
Poliovirus Picornaviridae
  • fecal-oral
None
  • vaccine
  • avoiding contaminated food and water
  • improved sanitation
Antibody detection
Rabies virus Rhabdoviridae
  • saliva
  • droplet contact
Post-exposure prophylaxis
  • vaccine
  • avoiding rabid animals
Histology (postmortem)
Respiratory syncytial virus Paramyxoviridae
  • droplet contact
  • direct contact
(ribavirin)
  • hand washing
  • avoiding close contact with the sick
  • palivizumab in high risk individuals
  • covering mouth when coughing/sneezing
antibody and antigen detection
Rubella virus Togaviridae
  • droplet contact
None
  • vaccine
  • avoiding close contact with the sick
Antibody detection
Varicella-zoster virus Herpesviridae
  • direct contact
  • droplet contact

Varicella:

Zoster:

Varicella:

Zoster:

  • vaccine
  • varicella-zoster immunoglobulin
  • Cell culture
  • antigen and nucleic acid detection

Notes[edit]

In 2010 it was reported that the presence of a begomovirus (Pepper mild mottle virus) in the stool was associated with clinical disease and a specific immune response.[6] If this association can be confirmed it is the first known case of disease caused by a virus previously considered pathogenic only to plants.

Diagnosis and treatment[edit]

Clinical presentation is used to detect viral disease by looking for history of severe muscle and joint pains before fever and also detect skin rash and lymph gland swelling. Laboratory investigations is not necessary to detect viral infections, because no increase in the white blood cells, the laboratory investigation is done to find other bacterial infections, if it is suspected. Viruses commonly have self-limited life, so treatment is usually reduce the symptoms only and antipyretic and analgesic drugs are commonly be used.[7]

See also[edit]

References[edit]

  1. ^ a b c d e f g h i j Fisher, Bruce; Harvey, Richard P.; Champe, Pamela C. (2007). Lippincott's Illustrated Reviews: Microbiology. Lippincott's Illustrated Reviews Series. Hagerstown MD: Lippincott Williams & Wilkins. pp. 354–366. ISBN 0-7817-8215-5. 
  2. ^ "Dr Manny: Why are there deadly viruses in the world?". Shreveport Times. June 11, 2014. 
  3. ^ Hunt, M. "Arboviruses". University of South Carolina School of Medicine. 
  4. ^ Le, Tao; Bhushan, Vikas; Vasan, Neil (2009). First Aid for the Usmle Step 1 2010. McGraw-Hill Prof Med/Tech. p. 169. ISBN 978-0-07-163340-6. 
  5. ^ Fisher, Harvey & Champe 2007, p. 315
  6. ^ Colson P., Richet H., Desnues C., Balique F., Moal V., Grob J., Berbis P., Lecoq H., Harlé J., Berland Y., Raoult D. (2010). "Pepper Mild Mottle Virus, a Plant Virus Associated with Specific Immune Responses, Fever, Abdominal Pains, and Pruritus in Humans". PLoS ONE 5 (4): e10041. doi:10.1371/journal.pone.0010041. PMC 2850318. PMID 20386604. 
  7. ^ "Viral Fever". Web Health Centre. Retrieved August 15, 2013.