Human-Herpesviruses-6-7-and-8-An-Overview(1).pptx

Hsv 6,7,8

1. Human Herpesviruses 6, 7, and 8: An Overview Present by : Sankhala Hasti Group: 20/19

2. Human Herpesviruses 6, 7, and 8: An Overview This presentation delves into the intricate world of Human Herpesviruses 6, 7, and 8 (HHV-6, HHV-7, and HHV-8), exploring their classification, virology, discovery, prevalence, and genomic structures. HHV-6 was identified in 1986, followed by HHV-7 in 1990, and HHV-8 in 1994. These double-stranded DNA viruses belong to the Betaherpesvirinae subfamily. Prevalence rates vary: HHV-6 affects over 90% of children by age 2, HHV-7 infects over 85% of adults, while HHV-8 prevalence differs among populations.

3. Human Herpesvirus 6 (HHV-6): Etiology and Pathology Variants HHV-6 has two variants: HHV-6A and HHV-6B. HHV-6B is the primary cause of exanthem subitum, commonly known as roseola infantum. While both variants share similarities, they differ in their epidemiology and neurovirulence. Transmission Salivary transmission is the most common route of infection. Vertical transmission, from mother to child during pregnancy, occurs in less than 1% of pregnancies. This highlights the importance of understanding transmission dynamics to implement preventive strategies.

4. Human Herpesvirus 6 (HHV-6): Etiology and Pathology Cellular Tropism The virus targets various immune cells, including CD4+ T cells, CD8+ T cells, NK cells, and monocytes/macrophages. It also infects glial cells in the nervous system. Understanding the cellular tropism of HHV-6 is crucial for comprehending its pathogenesis and clinical manifestations.

5. HHV-6: Clinical Manifestations and Diagnosis 1 Exanthem Subitum (Roseola Infantum) Characterized by a high fever (39-41°C) lasting for 3-7 days, followed by a distinctive maculopapular rash on the trunk. 2 Febrile Seizures Occur in 10-15% of children experiencing primary HHV-6 infection, representing a significant concern due to the potential for neurological complications and parental anxiety. Prompt diagnosis and management are essential. 3 Other Manifestations Rarely, HHV-6 infection can lead to more severe conditions such as encephalitis (inflammation of the brain), hepatitis (inflammation of the liver), and bone marrow suppression, highlighting the potential for systemic involvement and serious outcomes.

6. HHV-6: Treatment and Management Roseola Infantum Treatment primarily involves supportive care, focusing on managing symptoms such as fever and dehydration. Antipyretics help reduce fever, while adequate hydration is essential to prevent complications. Rest and careful monitoring are also important. Severe Cases In severe cases, such as encephalitis, antiviral therapy with ganciclovir or foscarnet may be considered. These medications can help reduce viral replication and limit the extent of neurological damage. However, their use should be carefully evaluated due to potential side effects. Monitoring for Complications Close monitoring is essential to detect and manage potential neurological sequelae, such as developmental delay and epilepsy. Early intervention and rehabilitation can help improve outcomes and quality of life for affected individuals. Ongoing support for families is also crucial

7. Human Herpesvirus 7 (HHV-7): Etiology and Pathology Etiology HHV-7 is a ubiquitous herpesvirus closely related to HHV-6. Its widespread presence underscores the importance of understanding its transmission dynamics and potential clinical implications. Transmission The primary mode of transmission is via saliva, highlighting the ease with which the virus can spread through close contact, especially among young children and within families. CD4+ T cells are the primary cellular target of HHV-7, which leads to immunosuppression. This can result in reactivation during periods of stress or immune compromise, potentially triggering various clinical manifestations. Cellular Tropism

8. HHV-7: Clinical Manifestations and Diagnosis 1 Asymptomatic Infections In many cases, HHV-7 infections are asymptomatic, meaning individuals may carry the virus without experiencing any noticeable symptoms. This makes it challenging to track the true prevalence and impact of HHV-7 in the general population. 2 Exanthem Subitum-Like Illness HHV-7 can cause an exanthem subitum-like illness, although this is less common than HHV-6B. The symptoms are similar, including fever and rash, which can make it difficult to distinguish between the two infections clinically. 3 Association with Pityriasis Rosea There is an association with pityriasis rosea, although this remains controversial. Pityriasis rosea is a skin condition characterized by a distinctive rash that typically begins with a single, large patch (herald patch) followed by smaller patches. While HHV-7 has been implicated, further research is needed.

9. HHV-7: Treatment and Management Supportive Care Treatment is primarily supportive, as most HHV-7 infections are self-limiting and resolve on their own without specific intervention. This involves managing symptoms like fever, providing adequate hydration, and ensuring rest. Antiviral Therapy In severe cases, such as those involving immunocompromised patients, antiviral therapy with medications like ganciclovir or foscarnet may be considered. However, these situations are rare, and the decision to use antiviral agents should be carefully weighed. Monitoring Close monitoring is important, particularly in immunocompromised patients, to detect and manage any potential complications. This may involve regular blood tests, clinical assessments, and imaging studies to track the course of the infection and identify any adverse effects.

10. Human Herpesvirus 8 (HHV-8): Etiology and Pathology Etiology HHV-8, also known as Kaposi's sarcoma-associated herpesvirus (KSHV), is the causative agent of Kaposi's sarcoma, primary effusion lymphoma (PEL), and multicentric Castleman's disease (MCD). Understanding its etiology is critical for developing targeted prevention and treatment strategies. 1 Transmission HHV-8 can be transmitted through various routes, including sexual contact, saliva, and possibly vertical transmission. The relative importance of each route may vary depending on the population and geographic region. Safe sex practices and good hygiene are important for preventing its spread. 2 Cellular Tropism HHV-8 exhibits broad cellular tropism, infecting B cells, endothelial cells, and other cell types. This versatility contributes to its ability to cause diverse clinical manifestations, including tumors of vascular origin and lymphoproliferative disorders. The virus hijacks cellular pathways to promote its replication and survival. 3

11. HHV-8: Clinical Manifestations and Diagnosis 1 Kaposi's Sarcoma (KS) 2 Primary Effusion Lymphoma (PEL) 3 Multicentric Castleman's Disease (MCD) Kaposi's Sarcoma (KS) manifests as a vascular tumor of the skin, mucous membranes, and internal organs. Primary Effusion Lymphoma (PEL) is a rare B-cell lymphoma arising in body cavities. Multicentric Castleman's Disease (MCD) presents as a lymphoproliferative disorder with systemic symptoms. Diagnosis involves PCR for HHV-8 DNA and immunohistochemistry for HHV-8 latent nuclear antigen (LANA) in tissue biopsies.

12. HHV-8: Treatment and Management Kaposi's Sarcoma Treatment options include local therapy (cryotherapy, radiation, excision), systemic therapy (chemotherapy, antiviral therapy), and immunotherapy. Primary Effusion Lymphoma Combination chemotherapy with or without antiviral therapy is the standard approach. Multicentric Castleman's Disease Immunomodulatory therapy (e.g., rituximab) and chemotherapy are commonly used.

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