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Category: Clinical Microbiology
Human Herpesviruses 6, 7, and 8, Page 1 of 2
< Previous page | Next page > /docserver/preview/fulltext/10.1128/9781555819156/9781555819149.ch29-1.gif /docserver/preview/fulltext/10.1128/9781555819156/9781555819149.ch29-2.gifAbstract:
Human herpesvirus 6 (HHV-6A and -6B variants), human herpesvirus 7 (HHV-7), and human herpesvirus 8 (HHV-8) were the last three herpesviruses identified, from 1986 to 1994 (1–3). HHV-6 and HHV-7 are ubiquitous viruses showing >95% prevalence worldwide from early childhood, usually with asymptomatic primary infection. HHV-6 has been associated with many clinical conditions, but attempts to establish clear etiologic relationships with human disease have largely been confounded by the ubiquity of HHV-6 and the only relatively recent formal recognition of variants HHV-6A and HHV-6B. The most well-recognized clinical presentations of HHV-6 infections, roseola infantum and fever, occur as a result of primary infection mainly in otherwise healthy infants and young children. Primary infection in adults is uncommon. Severe syndromes typically result from HHV-6 reactivation in immunocompromised hosts. Most infections are caused by HHV-6B; disease attributed to HHV-6A is rare. Both of the HHV-6 variants and HHV-7 have been associated with disease in immunocompromised organ transplant recipients. HHV-8 stands out as being the only human herpesviruses with low prevalence in most of the world and is mainly known as the etiologic agent of Kaposi's sarcoma (KS). Like other herpesviruses, these viruses establish lifelong infections in their host and are maintained through a combination of latent (nonproductive) infections and intermittent or persistent lytic infections; consequently, they present diagnostic challenges.
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The photomicrograph depicts histopathologic changes seen in a human skin biopsy of Kaposi's sarcoma, most notably the appearance of the dermal layer with a cellular infiltrate and proliferation of vascular elements.
The photomicrograph depicts histopathologic changes seen in a human skin biopsy of Kaposi's sarcoma, most notably the appearance of the dermal layer with a cellular infiltrate and proliferation of vascular elements.
The skin of a patient displaying characteristic reddish-brown cutaneous plaques indicative of Kaposi's sarcoma.
The skin of a patient displaying characteristic reddish-brown cutaneous plaques indicative of Kaposi's sarcoma.
Laboratory diagnosis of HHV-6
Laboratory diagnosis of HHV-6
Laboratory diagnosis of HHV-8
Laboratory diagnosis of HHV-8