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Types of Viral Disorders

by Craig R. Pringle, BSc, PhD

Categorizing viral infections by the organ system most commonly affected (eg, lungs, GI tract, skin, liver, CNS, mucous membranes) can be clinically useful, although certain viral disorders (eg, mumps) are hard to categorize. Many specific viruses and the disorders they cause are also discussed elsewhere in T he M anual .

Respiratory infections

The most common viral infections are probably URIs. Respiratory infections are more likely to cause severe symptoms in infants, the elderly, and patients with a lung or heart disorder.

Respiratory viruses include the epidemic influenza viruses (A and B), H5N1 and H7N9 avian influenza A viruses, parainfluenza viruses 1 through 4, adenoviruses, respiratory syncytial virus A and B, human metapneumovirus, and rhinoviruses (see Some Respiratory Viruses and see Respiratory Viruses). In 2012, a novel coronavirus, Middle East respiratory syndrome coronavirus (MERS-CoV—see Middle East Respiratory Syndrome (MERS)), appeared in Kuwait; it can cause severe acute respiratory illness and is sometimes fatal. Respiratory viruses are typically spread from person to person by contact with infected respiratory droplets.

Some Respiratory Viruses

Principal Syndromes

Prevalence and Distribution

Specific Therapy

Specific Prevention*

Epidemic influenza viruses A, B, and C and avian influenza viruses

Influenza

AFRD

Acute bronchitis and pneumonia

Croup

A and B: Epidemic, occasionally pandemic

C: Endemic

Global

A and B: Oseltamivir or zanamivir

A and B: Vaccine, oseltamivir or zanamivir

Avian H5N1 and avian H7N9: Poultry-associated

Oseltamivir

Avoiding contact with birds

Parainfluenza viruses 1–4

AFRD (children)

Acute bronchitis and pneumonia

Croup

1: Local epidemics

1, 2, and 3: Widespread in children

None

Vaccines under investigation

Adenoviruses

AFRD (children)

Acute respiratory disease (adults)

Acute pharyngoconjunctival fever

Epidemic keratoconjunctivitis

Viral pneumonia

Acute follicular conjunctivitis

Diarrhea

Hemorrhagic cystitis

Global

Mostly children

None

Vaccine containing types 4 and 7 for epidemics in military populations

Respiratory syncytial virus and human metapneumovirus

Lower respiratory illness (infants)

Mild upper respiratory illness (adults)

Widespread in children

Ribavirin sometimes used in immunocompromised patients

Palivizumab IM monthly (for certain infants at high risk of RSV infection)

Rhinoviruses

Common cold

Acute coryza with or without fever

Universal, especially during cold months

None

None

*Nonspecific precautions (eg, avoidance of infected patients and insect and animal vectors, routine hygiene measures) are also recommended.

Unlike RSV-IVIG, palivizumab does not interfere with immunizations (eg, MMR, chickenpox).

AFRD = acute febrile respiratory disease; IVIG = IV immune globulin; MMR =measles, mumps, and rubella; RSV = respiratory syncytial virus.

GI infections

Gastroenteritis is usually caused by viruses (see Gastroenteritis) and transmitted from person-to person by the oral-fecal route. Age group primarily affected depends on the virus:

  • Rotavirus: Children

  • Norovirus: Older children and adults

  • Astrovirus: Usually infants and young children

  • Adenovirus 40 and 41: Infants

  • Coronavirus-like agents: Infants

Local epidemics may occur in children, particularly during colder months.

The main symptoms are vomiting and diarrhea.

No specific treatment is recommended, but supportive care, particularly rehydration, is important.

A rotavirus vaccine that is effective against most pathogenic strains is part of the recommended infant vaccination schedule (see Table: Recommended Immunization Schedule for Ages 0–6 yr). Hand washing and good sanitation measures can help prevent spread.

Exanthematous infections

Some viruses cause only skin lesions (as in molluscum contagiosum and warts—see Viral Skin Diseases); others also cause systemic manifestations or lesions elsewhere in the body (see Some Exanthematous Viruses). Transmission is typically from person to person; alphaviruses have a mosquito vector.

Some Exanthematous Viruses

Principal Syndromes

Prevalence and Distribution

Specific Therapy

Specific Prevention*

Rubeola virus

Measles

Encephalomyelitis

CNS involvement (rare)

Global

Incidence decreasing because of vaccine

None

Vaccines

Rubella virus

German measles

Birth defects due to infection during pregnancy

Universal

None

Vaccines

Human parvovirus B19

Erythema infectiosum (fifth disease)

Rash, malaise, arthritis

Hydrops fetalis (infection during pregnancy)

Anemia (in immunocompromised hosts or patients with hemoglobinopathies)

Sporadic outbreaks

IVIG (for severe anemia)

None

Human herpesvirus type 6

Roseola infantum (exanthem subitum)

Widespread

Affects young children

None

None

Varicella-zoster virus

Chickenpox

Before vaccine, almost universal in children, occasionally in adults

Acyclovir, famciclovir, valacyclovir

Immune globulins, vaccine

Zoster

Common in adults, resulting from reactivation of latent virus

Acyclovir, famciclovir, valacyclovir

Vaccine

Variola

Smallpox

Natural disease eradicated

Cidofovir

Smallpox vaccine up to 4 days after exposure

Vaccine

Cidofovir

Alphaviruses (some)

Chikungunya disease (acute febrile illness followed by more chronic polyarthritis)

Transmitted by Aedes mosquitoes

Africa, Southeast Asia, India, Europe

None

None

Mayaro disease (a dengue-like disease)

Mosquito-borne

South America, Trinidad

None

None

Molluscum contagiosum virus

Molluscum contagiosum papules

Genital (adults)

Exposed skin (children)

More severe (AIDS patients)

Cryotherapy, curettage

None

*Nonspecific precautions (eg, avoidance of infected patients and insect and animal vectors, routine hygiene measures) are also recommended.

Based on animal studies.

IVIG = IV immune globulin.

Hepatic infections

At least 5 specific viruses (hepatitis A, B, C, D, and E viruses) can cause hepatitis; each causes a specific type of hepatitis (see Viral Hepatitis and see Hepatitis). Hepatitis D virus can infect only when hepatitis B is present. Transmission is from person to person by contact with infected blood or body secretions or by the fecal-oral route for hepatitis A and E.

Other viruses can affect the liver as part of their disease process. Common examples are cytomegalovirus, Epstein-Barr virus, and yellow fever virus. Less common examples are echovirus, coxsackievirus, and herpes simplex, rubeola, rubella, and varicella viruses.

Viral Hepatitis

Principal Syndromes

Prevalence and Distribution

Specific Therapy

Specific Prevention*

Hepatitis A (acute)

Widespread, often epidemic

None

γ-Globulin, vaccine

Hepatitis B (acute and chronic)

Widespread

Interferon, other antivirals, including nucleoside analogs (eg, entecavir) and nucleotide analogs (eg, tenofovir)

Screening for hepatitis B surface antigen

Vaccine, γ- or hyperimmune globulin

Hepatitis C (acute and chronic)

Widespread

Interferon, ribavirin

Screening for hepatitis C

Hepatitis D (delta)

Endemic pockets in several countries

Parenteral drug users at relatively high risk

Can infect only in the presence of hepatitis B

Interferon

None

Hepatitis E

Outbreaks

Developing world

Severe during pregnancy

None

Vaccine (not available in US)

*Nonspecific precautions (eg, avoidance of body fluids of infected patients, aseptic precautions, routine hygiene measures) are also recommended.

Neurologic infections

Most cases of encephalitis are caused by viruses (see Some Neurologic Viruses and Brain Infections). Many of these viruses are transmitted to humans by blood-eating arthropods, mainly mosquitoes and ticks (see Arboviridae, Arenaviridae, and Filoviridae); these viruses are called arboviruses (arthropod-borne viruses). For such infections, prevention includes avoiding mosquito and tick bites.

Some Neurologic Viruses

Principal Syndromes

Prevalence and Distribution

Specific Therapy

Specific Prevention*

Polioviruses

Poliomyelitis (acute flaccid paralysis)

Aseptic meningitis

Global

Incidence now low because of vaccine

None

Vaccines: Live (oral), killed (injected)

Alphaviruses (some), mosquito-borne

Western equine encephalitis

North and South America

None

None

Eastern equine encephalitis

North and South America

None

Vaccine available to protect equines only

Venezuelan equine encephalitis

Gulf states to South America

None

Vaccine available for equines

Investigational vaccine used in laboratory workers at risk

Flaviviruses (some), mosquito-borne

Japanese encephalitis

Southeast Asia, Japan, Korea, China, India, Philippines, eastern former Soviet Union

None

Vaccine

Murray Valley encephalitis

Australia, New Guinea

None

None

St. Louis encephalitis

North and South America

None

None

West Nile virus encephalitis

Africa, Middle East, southern France, former Soviet Union, India, Indonesia, US

None

Screening blood and blood products for the virus

Flaviviruses (some), tick-borne

Powassan encephalitis

Canada, northeastern US

None

None

Tick-borne encephalitis

Eastern and Central Europe, Balkans, former Soviet Union

Outbreaks that coincide with periods of tick activity

None

Vaccine available in Europe and Russia

Bunyaviruses (some), mosquito-borne

California encephalitis and related types (eg, La Crosse encephalitis)

Probably worldwide

Common in Midwestern and eastern US

Symptomatic infection primarily in children

None

None

Arenaviruses (some)

Lymphocytic choriomeningitis

US, Europe, possibly elsewhere

Chief reservoir: House mouse

Primarily in adults during autumn and winter

None

None

Rabies virus

Rabies

Worldwide

None

Vaccine

Postexposure rabies immune globulin

*Nonspecific precautions (eg, avoidance of contaminated food and water and insect and animal vectors, routine hygiene measures) are also recommended.

Hemorrhagic fevers

Certain viruses cause fever and a bleeding tendency (see Some Viruses That Cause Hemorrhagic Fever and Arboviridae, Arenaviridae, and Filoviridae). Transmission may involve mosquitoes, ticks, or contact with infected animals (eg, rodents, monkeys, bats) and people. Prevention involves avoiding the means of transmission.

Some Viruses That Cause Hemorrhagic Fever

Principal Syndromes

Distribution

Specific Therapy

Specific Prevention*

Flaviviruses (some)

Omsk hemorrhagic fever

Former Soviet Union (Siberia)

None

None

Kyasanur Forest disease

India

None

None

Yellow fever

Africa, Central and South America

None

Vaccine for travelers to endemic areas and for populations experiencing an outbreak

Dengue fever

Tropics and subtropics, worldwide

None

None

Bunyaviruses (some)

Hemorrhagic fever with renal syndrome due to Hantaan, Puumala, Dobrava (Belgrade), or Seoul virus

Northern Asia, Europe, southwestern US

Ribavirin

None

Filoviruses

Lake Victoria marburgvirus disease

Africa

None

None

Sudan ebolavirus disease

Africa, Sumatra

None

None

Bundibugyo ebolavirus disease

Uganda

None

None

Zaire ebolavirus disease

Zaire

None

None

Reston ebolavirus disease

Philippines

None

None

Arenaviruses (some)

Lassa fever

Bolivian hemorrhagic fever (due to Machupo virus)

Argentinian hemorrhagic fever (due to Junin virus)

Venezuelan hemorrhagic fever (due to Guanarito virus)

Brazilian hemorrhagic fever (due to Sabia virus)

South America, Africa (only Lassa fever)

Ribavirin

Convalescent plasma for all except Lassa fever

Vaccine for Argentinian hemorrhagic fever under investigation

Lujo virus disease

Zambia

None

None

Nairovirus

Crimean-Congo hemorrhagic fever

Former Soviet Union, western Pakistan, Africa, Asia, Middle East, Eastern Europe

Ribavirin

Possibly convalescent plasma

Vaccine available in Eastern Europe

*Nonspecific precautions (eg, avoidance of the means of transmission, routine hygiene measures) are also recommended.

Cutaneous or mucosal infections

Some viruses cause skin or mucosal lesions that recur and may become chronic (see Some Viruses That Cause Recurrent or Chronic Skin or Mucosal Lesions). Mucocutaneous infections are the most common type of herpes simplex virus infection (see Herpes Simplex Virus (HSV) Infections). Human papillomavirus causes warts (see Warts); some subtypes cause anogenital and oropharyngeal cancer (see Genital Warts and Cervical Cancer). Transmission is by person-to-person contact.

Some Viruses That Cause Recurrent or Chronic Skin or Mucosal Lesions

Principal Syndromes

Prevalence

Specific Therapy

Specific Prevention*

Herpes simplex virus

Herpes labialis

Herpetic gingivostomatitis

Dermatitis

Keratoconjunctivitis

Encephalitis

Vulvovaginitis

Neonatal disseminated disease

Labial: Recurrent, almost universal

Gingivostomatitis: Frequent in infants and children

Acyclovir, famciclovir, valacyclovir, penciclovir

Neonatal infection: Treatment of maternal infection; suppressive therapy beginning at 36 wk of gestation if patients have a history of recurrent HSV; cesarean delivery if lesions or prodromal symptoms are present at time of delivery

Human papillomavirus

Warts (verrucae)

Genital warts

Cervical, anogenital, and oropharyngeal cancer

Universal

Common, often recurrent

Cryotherapy, interferon (possibly for genital), podophyllin (genital), imiquimod

Vaccine for the 4 subtypes of HPV most commonly associated with cancers and genital warts

Condoms

*Nonspecific precautions (eg, routine hygiene measures, safe-sex practices) are also recommended.

Multisystem diseases

Enteroviruses, which include coxsackieviruses and echoviruses (see Enteroviruses), can cause various multisystem syndromes, as can cytomegaloviruses (see Some Viruses That Cause Multisystem Disease and Cytomegalovirus (CMV) Infection). Transmission is by the fecal-oral route.

Some Viruses That Cause Multisystem Disease

Principal Syndromes

Distribution and Prevalence

Specific Therapy

Specific Prevention*

Coxsackieviruses

Herpangina

Epidemic pleurodynia

Aseptic meningitis

Meningoencephalitis

Neonatal sepsis

Myocarditis

Pericarditis

AFRD (children)

Paralysis

Fever and exanthem

Varies with types

Most people infected

Increased during warm months in temperate climates and year round in the tropics and in children

Person-to-person spread usually via the fecal-oral route

None

None

Echoviruses and high-numbered enteroviruses

Aseptic meningitis

Fever and exanthem

Meningoencephalitis

Neonatal sepsis

Paralysis

Myocarditis

Pericarditis

As for coxsackieviruses

None

None

Cytomegalovirus

Congenital defects (cytomegalic inclusion disease)

Hepatitis (cytomegalovirus mononucleosis)

In immunocompromised patients (including those with AIDS): Retinitis, GI disorders, CNS disorders, pneumonia

Widespread

Congenital

Common among immunocompromised patients

Ganciclovir, foscarnet, cidofovir, sometimes immune globulin (eg, in organ transplant recipients with pneumonia)

Ganciclovir, foscarnet

*Nonspecific precautions (eg, adequate sanitation, hand washing) are also recommended.

Echovirus types 10, 21, 22, and 28 have been reclassified; these numbers are no longer used. More recently described enteroviruses have been designated as types 68 to 72.

AFRD = acute febrile respiratory disease.

Nonspecific febrile illness

Some viruses cause nonspecific symptoms, including fever, malaise, headaches, and myalgia (see Some Viruses That Cause Nonspecific Acute Febrile Illness and see Table: Arbovirus, Arenavirus, and Filovirus Diseases). Transmission is usually by an insect or arthropod vector.

Rift Valley fever rarely progresses to ocular disorders, meningoencephalitis, or a hemorrhagic form (which has a 50% mortality rate).

Some Viruses That Cause Nonspecific Acute Febrile Illness

Principal Syndromes

Distribution

Specific Therapy*

Specific Prevention

Colorado tick fever virus (coltivirus)

Colorado tick fever, with leukopenia and thrombocytopenia

Western US, Canada

None

None

Phleboviruses (some)

Phlebotomus (sandfly) fever

Mediterranean basin, Balkans, Middle East, Pakistan, India, China, eastern Africa, Panama, Brazil

None

None

Rift Valley fever

Eastern Africa, Egypt

None

Vaccine for livestock

Human vaccine under investigation

Severe fever with thrombocytopenia syndrome

China, Korea, Japan

None

None

*Treatment is usually supportive.

Nonspecific precautions (eg, avoidance of the means of transmission, routine hygiene measures, screening of bone marrow used for transplantation) are also recommended.

Resources In This Article

Drugs Mentioned In This Article

  • Drug Name
    Select Trade
  • VIRAZOLE
  • TAMIFLU
  • RELENZA
  • SYNAGIS
  • ZOVIRAX
  • FAMVIR
  • VISTIDE
  • VALTREX
  • VIREAD
  • BARACLUDE
  • DENAVIR
  • ALDARA
  • CYTOVENE
  • FOSCAVIR

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