Adenoviruses are unenveloped, icosahedral, double-stranded DNA viruses that possess species-specific, group-specific and typespecific antigens. There are more than 50 serotypes of human adenoviruses, which are divided into six groups (A-F) on the basis of their genomic homology.
Epidemiology and Clinical features
Diagnosis is usually made by nucleic acid amplification test (NAAT) but culture, serology and electron microscopy (EM) Diagnosis are available.
Prevention and control
Outbreaks must be managed according to infection control practices (both respiratory and contact). Outbreaks of ocular infection at swimming pools are prevented by adequate chlorination. Transmission between patients undergoing ophthalmic examination can be prevented by single-use equipment, adequate decontamination of equipment and appropriate hygiene by healthcare staff.
Parvoviruses are small, unenveloped, icosahedral, single-stranded DNA viruses with one serotype, B19, known to cause human disease and given the genus name Erythrovirus.
Infection is found worldwide and throughout the year. Transmission is by the respiratory route. It may cause outbreaks of erythema infectiosum in schools. Seroprevalence increases with age with more than 60% of adults possessing antibody.
Pathogenesis and Clinical features
Prevention and control
No specific treatment or vaccine is available at present. Respiratory precautions should prevent transmission in the hospital environment.
These are small, enveloped, double-stranded DNA viruses with more than 100 types. Some are responsible for common warts and genital warts. Types 16 and 18 predominate in cervical neoplasia; they are transmitted by close contact, including by the sexual route. Diagnosis of a common wart is clinical; cervical neoplasm is diagnosed by cytology and NAAT. A vaccine against types 6, 11, 16 and 18 is now in use.
Poxviruses are double-stranded DNA viruses with complex symmetry and a shape that resembles a ball of wool.
Once a major cause of death worldwide this has now been eradicated but there are concerns that smallpox may become a bioterrorism weapon, which have prompted some countries to produce stocks of vaccine.
A zoonotic infection in rainforest areas of Central and West Africa that is similar to smallpox. The case fatality rate can reach 10% in Africa, but was much lower in the USA where there was an outbreak associated with infected prairie dogs. Diagnosis is by EM or NAAT.
A zoonotic, pustular dermatitis originating in sheep and goats that is characterized by a single vesicular lesion, which is typically found on the finger and resolves spontaneously after a few weeks. Diagnosis is usually clinical on the basis of appearance and a history of exposure.
Tanapox is a febrile illness usually associated with a single nodular skin lesion that may ulcerate and heal spontaneously. Infection is acquired in central and east Africa; the diagnosis is usually suggested by the travel history and can be confirmed by EM or NAAT.
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