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Germs that infect humans

Herpes virus

Herpes virus

© Robert Alain, SME, INRS-Institut Armand-Frappier

Microorganism: herpes simplex type 1 virus, family: Herpesviridae.

Disease: cold sores

Occurrence of the disease

History: Hippocrates, the ancient Greek physician, described the symptoms of cold sores in approximately 400 BC.

Current situation: this virus is the greatest cause of blindness in the United States. It is estimated that 50-90% of all adults in the world have been infected by this virus.

Mechanism of action of the microorganism: the virus attacks skin cells, most commonly of the lips, mouth or gums. The accumulation of the virus and of dead cells causes blisters to form. The virus remains present even after the small eruptions caused by the virus have healed (within a week) and migrates to lymph glands, where they remain in an inactive form for the rest of the individual's life. From time to time, the virus becomes active again and reinfects the lips, mouth or gums, causing new cold sores to appear. Cold, fever, excessive sunlight, and stress appear to be triggers for the reactivation of the virus.

Symptoms of the disease: eruptions (blisters) around the mouth, lips or gums. In serious cases, the virus may infect the cornea (the transparent covering of the eye), causing a condition known as herpetic keratitis that may cause a loss of vision.

Incubation period: two to 12 days.

Contagious period: two to seven weeks.

Hosts: humans.

Transmission: direct contact with cold sores.

Treatment of the disease: acyclovir and vidarabine are antiviral agents that partially eradicate the virus.

Geographical distribution of the microorganism: worldwide.

Prevention: avoidance of kissing individuals with cold sores.

Vaccine: none.