Pox viruses
Pox virus is enveloped. They are largest and most complex virus of vertebrates. They are DNA virus.
Morphology
Pox viruses are brick shaped.
Size; 300 X 200 X 100nm in size, seen under light microscope.
Cultivation
Grow in CAM of chick embryo and in tissue culture.
Pox Virus Causing Human Infection;
1. Variola virus
2. Vaccinia Virus; cause vaccinia (localized skin infection)
3. Molluscum contagiosum
2. Herpes Virus
Pox virus Causing Human Infection;
1. Variola virus
Variola virus causes small pox. It is infectious disease manifested as skin lesions, known as complex virus.
A natural infection of small pox gives complete protection against reinfection.
2. Vaccinia virus; cause vaccinia (localized skin infection)
3. Molluscum contagiosum
Epidermal tumor - like lesion occurs in human body.
Pathogenesis
Incubation period is about 12 days.
The rashes appear 3rd-4th day on buccal mucosa which develop into macule which change into papule, vesicle and finally pustule which dry up in 10-12 days.
They may lead conjunctivitis and lesion on cornea may cause reason of blindness.
Sources and Modes of Infection
Small pox causes by variola virus and is spread from person to person.
Small pox spread when an infected person talks, cough, sneeze, small droplet containing infectious agent in air.
Variola Virus is transmitted by respiratory route.
Laboratory Diagnosis
Specimen; Sputum, blood, lesions
Isolation; Cultured on CAM of chick embryo. Virus is detected by characteristics pocks produce in CAM.
Virus; Demonstrated by electron microscope viruses antigen and antibody.
Prophylaxis
Vaccines prepared from these strains of Viruses;
1. Elstree strain
2. EM63 strain
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