Insects Arthropod borne disease Vector transmit the infection from infected to

Insects arthropod borne disease vector transmit the

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Insects Arthropod borne disease Vector: transmit the infection from infected to non infected individual Sources of Infection in Man Mechanical does not support pathogen multiplication e.g: transmission of dysentery by house fly Biological pathogen multiplies in the vector e.g : anopheles mosquito in malaria Vector
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Reservoir An environment with a continuous supply of microbes Infectious agents normally lives and multiplies e.g: ticks in relapsing fever and spotted fever It is of two types: Living: Man, animal, plant Non living: soil, water
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Soil May as source of parasite infection like roundworm and hookworm. Bacterial infections by spore forming bacteria Spores of tetanus bacilli or higher bacteria like Nocardia asteroides Fungal infection ike Histoplasma capsulatum Water Vibrio cholerae, Hepatitis-A virus
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Food Presence of pathogens in food may be due to external contamination ,e.g. food poisoning by Staphylococcus aureus
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Methods of Transmission of Infection Transmission Direct contact e.g: Gonorrhea, syphilis, trachoma Inhalation e.g : Influenza, Tuberculosis Inoculation e.g: Hepatitis B Tetanus Congenital e.g: Rubella, Toxoplasma Laboratory accidents e.g: Brucella,HBV Fecal- oral infection e.g: Cholera, Hepatitis A Insect bite e.g: Malaria
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Pathogenicity The ability of microbial species to produce disease Virulence The extent or the degree of the pathology caused by a microorganism. Differences in the efficiency with which different strains can cause symptoms e.g. Polio virus contains strain of varying degree of virulence. Pathogenicity vs Virulence
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Invasiveness Toxegenicit y Communicabilit y Infecting dose Route of infection Bacterial capsule & other bacterial products Determining Factors of Virulence
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Invasiveness The ability of organism to spread in a host tissue after establishing infection Less invasive organisms cause localized lesion, e.g. staphylococcal abscess Highly invasive organisms cause generalized infection, e.g. streptococcal septicemia
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Toxigenicity Exotoxin : Heat l abile proteins Endotoxin: Heat stable lipopolysaccharide
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Exotoxin Cannot cause pyrexia( fever ) in a host Can be toxoided Specific pharmacological effects for each exotoxin.
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