Molluscum contagiosum pathophysiology
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Molluscum contagiosum Microchapters |
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Diagnosis |
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Treatment |
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Case Studies |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1];Associate Editor(s)-in-Chief: Mahshid Mir, M.D. [2]
Overview
This is a common infection in children and occurs when a child comes into direct contact with a lesion. The virus can spread through contact with contaminated objects, such as towels, clothing, or toys. The virus also spreads by sexual contact. Persons with a weakened immune system (due to conditions such as AIDS) may have a rapidly worse case of molluscum contagiosum.
Pathophysiology
The time from infection to the appearance of lesions ranges from 1 week to 6 months, with an average incubation period of 6 weeks. Diagnosis is made on the clinical appearance.
Transmission
In adults, molluscum infections are often sexually transmitted and usually affect the genitals, lower abdomen, buttocks, and inner thighs. In rare cases, molluscum infections are also found on the lips, mouth, and eyelids. It is spread through direct contact or shared articles of clothing (including towels).
Virology
MC has no animal reservoir, infecting only humans, as did smallpox. However, there are different pox viruses that infect many other mammals. The infecting human MC virus is a DNA poxvirus called the molluscum contagiosum virus (MCV). There are 4 types of MCV, MCV-1 to -4, with MCV-1 being the most prevalent and MCV-2 seen usually in adults and often sexually transmitted. The virus cannot routinely be cultured.
Overview
- The overview section should include the disease name in the first sentence.
- The goal is to summarize the pathophysiology page in several sentences. This section can be the same as the pathophysiology segment on the overview page.
- To see an example of an overview section on a symptoms page, click here.
Template
- The overview is highly dependent on the individual disease pathophysiology. There is no specific template preference for the first sentence.
- Template Sentences:
- Template Sentence 1: [Pathogen name] is usually transmitted via the [transmission route] route to the human host.
- Template Sentence 2: Following transmission/ingestion, the [pathogen] uses the [entry site] to invade the [cell name] cell.
- Template Sentence 3: On gross pathology, [feature1], [feature2], and [feature3] are characteristic findings of [disease name].
- Template Sentence 4: On microscopic histopathological analysis, [feature1], [feature2], and [feature3] are characteristic findings of [disease name].
- Template Sentence 5: [Disease name] is transmitted in [mode of genetic transmission] pattern.
- Template Sentence 6: [Disease/malignancy name] arises from [cell name]s, which are [cell type] cells that are normally involved in [function of cells].
- Template Sentence 7: Development of [disease name] is the result from multiple genetic mutations.
- Template Sentence 8: Genes involved in the pathogenesis of [disease name] include [gene1], [gene2], and [gene3].
- Template Sentence 9: The progression to [disease name] usually involves the [molecular pathway].
- Template Sentence 10: The pathophysiology of [disease name] depends on the histological subtype.
- Examples:
- Example 1: Spores of C. difficile are transmitted via the fecal-oral route to the human host.
- Example 2: Following ingestion, the acid-resistant spores of C. difficile are able to survive the human gastric acidity.
- Example 3: Following ingestion, Shigella spp. uses the M cells of the GI tract to invade the epithelial cells of the large intestine.
- Example 4: Following transcytosis and macrophage apoptosis, Shigella avoids extracellular exposure and spreads intercellularly using actin polymerization processes (rocket propulsion).
- Example 5: On gross pathology, hyperemia with development of ulcers and edema are characteristic findings of shigellosis.
- Example 6: On microscopic histopathological analysis, infiltration of PMN and inflammatory pseudomembrane formation are characteristic findings of shigellosis.
- Example 7: Duchenne muscular dystrophy is transmitted in an X-linked recessive pattern.
- Example 8: Malignant melanoma arises from the epidermal melanocytes, which are neural crest cells normally involved in the synthesis of melanin (a brown pigment with photoprotective properties).
- Example 9: Development of melanoma is the result of multiple genetic mutations.
- Example 10: Genes involved in the pathogenesis of melanoma include p53, RB, ARF, and BRAF.
- Example 11: The progression to melanoma usually involves the serine-threonine kinases of the MAPK/ERK pathway (mitogen-activated protein kinase) following mutation of either the N-RAS or BRAF oncogene.
- Example 12: The pathophysiology of gallbladder cancer depends on the histological subtype.
Pathogenesis
- Molluscum contagiosum is a member of the poxvirus family
- causes a chronic localized infection with small papules on the skin of an infected individual in contrast to the acute, sometimes fatal, disease induced by smallpox.
- the only known host for molluscum is humans
- inability to grow the virus in standard cell culture or in an animal model of infection.
- reports of some success in growth using human foreskin xenograft fragments.[1]
- (MCV) commonly causes asymptomatic cutaneous neoplasms in children and sexually active adults as well as persistent opportunistic acquired immunodeficiency syndrome (AIDS)-associated disease. [1]
- Sequencing the 190-kilobase pair genome of MCV has now revealed that the virus potentially encodes 163 proteins, of which 103 have homologs in the smallpox virus. MCV lacks counterparts to 83 genes of the smallpox virus, including those important in suppression of host responses to infection, nucleotide biosynthesis, and cell proliferation. MCV possesses 59 genes that are predicted to encode previously uncharacterized proteins, including major histocompatibility complex class I, chemokine, and glutathione peroxidase homologs, which suggests that there are MCV-specific strategies for coexistence with the human host.[1]
- Analysis of the molluscum contagiosum virus (MCV) genome revealed that it encodes approximately 182 proteins, 105 of which have direct counterparts in orthopoxviruses (OPV).
- The corresponding OPV proteins comprise those known to be essential for replication as well as many that are still uncharacterized, including 2 of less than 60 amino acids that had not been previously noted. The OPV proteins most highly conserved in MCV are involved in transcription; the least conserved include membrane glycoproteins. Twenty of the MCV proteins with OPV counterparts also have cellular homologs and additional MCV proteins have conserved functional motifs. Of the 77 predicted MCV proteins without OPV counterparts, 10 have similarity to other MCV proteins and/or distant similarity to proteins of other poxviruses and 16 have cellular homologs including some predicted to antagonize host defenses. Clustering poxvirus proteins by sequence similarity revealed 3 unique MCV gene families and 8 families that are conserved in MCV and OPV. Two unique families contain putative membrane receptors; the third includes 2 proteins, each containing 2 DED apoptosis signal transduction domains. Additional families with conserved patterns of cysteines and putative redox active centers were identified. Promoters, transcription termination signals, and DNA concatemer resolution sequences are highly conserved in MCV and OPV. Phylogenetic analysis suggested that MCV, OPV, and leporipoxviruses radiated from a common poxvirus ancestor after the divergence of avipoxviruses. Despite the acquisition of unique genes for host interactions and changes in GC content, the physical order and regulation of essential ancestral poxvirus genes have been largely conserved in MCV and OPV.[2]
- replicates in the cytoplasm of cells, and thus, it is not surprising that more than one-half of the genes are similar to those found in variola and vaccinia viruses.
- Pathogenesis is the mechanism by which a certain factor causes disease (pathos = disease, genesis = development). The term can also be used to describe the development of the disease, whether it is acute, chronic, or recurrent. It can also be used to describe whether the disease causes inflammation, malignancy,necrosis etc.
- For an example of a pathogenesis section within a pathophysiology page, click here
Genetics
- Some diseases are genetic, and have particular inheritance patterns, and express different phenotypes.
- The effect that genetics may have on the pathophysiology of a disease can be described in this section.
Associated Conditions
- Conditions associated with the disease can be detailed in this section.
- For an example of an associated conditions sub-section of pathophysiology, click here.
Gross Pathology
- Gross pathology refers to macroscopic or larger scale manifestations of disease in organs, tissues and body cavities. The term is commonly used by pathologist to refer to diagnostically useful findings made during the gross examination portion of surgical specimen processing or an autopsy.
- This section is a good place to include pictures. Search for copyleft images on The Pathology Wiki [3] and Ask Dr. Wiki [4].
- For an example of this section, click here.
Microscopic Pathology
- Microscopic pathology is the disease process as it occurs at the microscopic level.
- This section is a good place to include pictures. Search for copyleft images on The Pathology Wiki [5] and Ask Dr. Wiki [6].
- For an example of this section, click here.
References
- ↑ 1.0 1.1 1.2 Fife KH, Whitfeld M, Faust H, Goheen MP, Bryan J, Brown DR (1996). "Growth of molluscum contagiosum virus in a human foreskin xenograft model". Virology. 226 (1): 95–101. doi:10.1006/viro.1996.0631. PMID 8941326.
- ↑ Senkevich TG, Koonin EV, Bugert JJ, Darai G, Moss B (1997). "The genome of molluscum contagiosum virus: analysis and comparison with other poxviruses". Virology. 233 (1): 19–42. doi:10.1006/viro.1997.8607. PMID 9201214.