Pathogen Project PathogensHaemophilus influenza

Pathogen Project PathogensHaemophilus influenza - Causative...

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Causative agent: Haemophilus influenzae Category: Bacteria Kingdom: Bacteria Phylum: Proteobacteria Class : Gamma Proteobacteria Order: Pasteurellales Family: Pasteurellaceae Genus: Haemophilus Species: influenzae Disease: H. influenzae is highly adapted to its human host. It is present in the nasopharynx of approximately 75 percent of healthy children and adults. It is rarely encountered in the oral cavity and it has not been detected in any other animal species. It is usually the non encapsulated strains that are harbored as normal flora, but a minority of healthy individuals (3-7 percent) intermittently harbor H. influenzae type b (Hib) encapsulated strains in the upper respiratory tract. Pharyngeal carriage of Hib is important in the transmission of the bacterium. The success of current vaccination programs against Hib is due in part to the effect of vaccination on decreasing carriage of the organism. Commonly inhabits the mucous membranes of the upper respiratory tract, moth, vagina, and intestinal tract. Erroneously believed to be responsible for influenza. Common cause of meningitis in young children and is a frequent cause of earaches. Other clinical conditions caused by H. influenzae include Epiglottitis (a life threatening condition in which the epiglottis becomes infected and inflamed), septic arthritis in children, bronchitis and pneumonia, pharyngitis, cellulitis, tonsillitis, septicemia, endocarditis. The pathogenesis of H. influenzae infections is not completely understood, although the presence of the type b polysaccharide capsule is known to be the major factor in virulence. Encapsulated organisms can penetrate the epithelium of the nasopharynx and invade the blood capillaries directly. Their capsule allows them to resist phagocytosis and complement- mediated lysis in the non-immune host. Non-typable (non-encapsulated) strains are less invasive, but they are apparently able to induce an inflammatory response that causes disease. Outbreaks of H. influenzae type b infection may occur in nurseries and child care centers, and prophylactic administration of antibiotics is warranted. Vaccination with type b polysaccharide (in the form of Hib conjugate vaccines) is effective in preventing infection, and several vaccines are now available for routine use.
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This note was uploaded on 05/11/2011 for the course BIO 31 taught by Professor Silva during the Spring '11 term at Reedley.

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Pathogen Project PathogensHaemophilus influenza - Causative...

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