Adenovirus infections B34.0

Adenoviruses were first isolated from tonsils and adenoid tissue (hence the name adenovirus) by Rowe in 1953.

Human pathogenic adenoviruses (Adenoviridae, serotypes 1-47) are DNA viruses classified according to 3 major capsid antigens (hexon, penton, and fiber). There are 7 human adenovirus species (A through G). The different serotypes cause a variety of diseases, including respiratory, gastrointestinal, ocular conjunctival, and corneal. The viruses are highly contagious and resistant.

Adenoviruses dock to the cellular receptor with the button-like ends of their fibers. This is the case with most CAR (coxsackie adenovirus receptor) virus types. In the course of penetration through the cell membrane, the virus loses its fibers and is taken up into the endosome. In the endosome, the capsid of the virus is partially destroyed by a viral protease and transported to a nuclear pore. Here, the genomic DNA is inserted into the karyoplasm and anchored therein with the help of the terminal protein TP. With the help of cellular transcription factors , the early proteins are now expressed, including a viral DNA polymerase that is required for DNA replication. Morphogenesis of new viral particles takes place in the nucleus. With dissolution of the nuclear membrane and death of the cell, the new particles are released.

Human pathogenic adenoviruses (serotypes 1-47) are causative agents of numerous diseases of different organ systems. Seasonal accumulations are not recognizable. Infections often occur in community settings such as day care centers.

Mainly affected are:

• Eyes
• Pharynx
• respiratory and
• gastrointestinal tract.

Acute respiratory infections often occur epidemically in young adults in close community.

The infections mainly affect infants, children and adolescents. About 5% of all "common colds" in infants <5 years of age are caused by adenoviruses. Path of infection: smear and droplet infection. The indirect transmission via contaminated surfaces is possible. Adenoviruses can also be transmitted via air and water - for example when swimming.

At the age of 5 years, most children have experienced an adenovirus infection, but 50% of them are inapparent.

Infections with adenoviruses are usually asymptomatic in immunocompetent individuals or lead to specific syndromes such as respiratory infections, keratoconjunctivitis, gastroenteritis, cystitis and primary pneumonia. The diagnosis is made clinically. Adenoviral infections are increasingly recognised as the cause of severe respiratory and other clinical conditions in immunocompromised adults.

Classification:

• Infections of the eye
  • Acute Hemorrhagic Conjunctivitis
  • Keratoconjunctivitis epidemica: This disease is sometimes severe and occurs sporadically as well as in epidemic form. The pathogens are serotypes 8,19,37. The conjunctivitis is often bilateral. Preauricular adenopathy may develop. Chemosis, pain and punctiform corneal lesions may be present (detection by fluorescein staining). Systemic symptoms are usually absent. Healing mostly within 3-4 weeks.
• respiratory infections
  • Acute respiratory disease, pharyngitis, bronchitis
  • Pharyngoconjunctival fever (combined febrile pharyngitis/conjunctivitis) is caused by adenovirus types 3 and 7.
  • Pneumonia (about 10% of all childhood pneumonia; types 1-4, 7,14)
  • Pertussis syndrome (indistinguishable from the real whooping cough)
• Infections in the urogenital tract
  • Cystitis
  • Acute haemorrhagic cystitis (benign macrohaematuria, almost exclusively affecting boys)
  • Genital ulcers (sexually transmitted infection - STID)
• Other infections
  • Gastroenteritis with and without mesenteric lymphadenopathy (after rotavirus, adenovirus is the second most common pathogen; serotypes 40 and 41 account for up to 15% of all diarrhoeal diseases in young children)
  • Meningitis

In contrast to viral infections caused by other viruses, adenovirus infections often involve leukocytosis and a (usually mild) increase in CRP.

Virus isolation, detection of viral DNA by PCR; further antibody detection: 4-fold increase in titer within 2 weeks

Isolation of the virus can be done from pharyngeal rinsing water, from an eye swab, stool or urine. It plays a clinically important role, especially in infections of the eye and respiratory tract.

In case of enteric diseases, the viruses can be detected by electron microscopy. However, since adults often develop cross-reactive antibodies in the course of life, serological diagnosis is more appropriate in children.

Symptomatic

Ribavirin and cidofovir have been used in immunocompromised patients; the results vary.

Vaccines containing live adenoviruses of types 4 and 7, administered orally in an enteric coated capsule, can prevent most diseases caused by these two species. The vaccine was not available for several years, but was reintroduced in 2011. However, it is only available to military personnel.

The vaccine can be given to patients between 17 and 50 years of age and should not be given to women who are pregnant or breastfeeding.

To minimize the risk of transmission, medical personnel should change gloves and perform hygienic hand disinfection after examining infected patients, properly sterilize instruments, and not share the same ophthalmic instruments for multiple patients.

Humans are the only source of infection for adenoviruses. These are highly resistant to environmental influences, which favours their transmission. Adenoviruses are often transmitted through contact with secretions (including those on the fingers of infected persons) from an infected person or through contact with a contaminated object (e.g. towel, instrument).

However, aerogenic or aquagenic transmission is also possible (e.g. when swimming). Asymptomatic respiratory or gastrointestinal virus excretion can persist for months or even years.

A 6-year-old girl in reduced general condition, febrile, with otitis media bds., rhinitis and an ubiquitous petechial and urticarial non-itchy exanthema. No meningitic signs.

Laboratory: Increased signs of inflammation in the blood, nasopharyngeal secretion positive for adenovirus.

Course: After healing of the respiratory infection generalized exanthema persisting for months with disseminated, erythematous papules 0,2-0,5 cm in size, some of them crusty. Hemorrhagic component in places. Varioliform scars, subjectively not disturbing, no itching.

Diagnosis: Pityriasis lichenoides et varioliformis acuta.

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