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Germs that infect humans


Herpes virus

Herpes virus

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

Microorganism: the herpes simplex type 2 virus belongs to the family Herpesviridae

Disease: genital herpes

Occurrence of the disease

History: in the United States, genital herpes can be found in 20 to 30% of adults. This rate increases dramatically (to more than 60%) among people with several sexual partners.

Mechanism of action of the microorganism: the virus penetrates inside the cell and multiplies, causing an immune system reaction that gives rise to sores. When the sores heal, the virus withdraws to neighboring nerve cells from where it returns periodically to re-infect the genitals.

Symptoms of the disease: fever, burning sensation, pain in the genitals. Some sores can appear and disappear on the penis and in the vagina. A large quantity of viruses is produced inside these sores.

Incubation period: about one week

Contagious period: the contagious period is intermittent. It is often associated with the presence of sores but these are not required for the disease to be transmitted.

Hosts: humans

Transmission: sexual contact. An infected woman can also transmit the disease to her child during childbirth. This infection, known as congenital herpes, can be fatal in newborns. This type of infection affects nearly 2,000 babies per year in the United States.

The sores heal in a few weeks but small quantities of the virus remain. This is why the sores reappear periodically for no apparent reason. Some researchers believe that stress, fever, or sunlight can cause the reappearance of the sores. This disease is said to be latent which means that it remains even if the affected person has no symptoms. The viruses are always present but in variable quantities.

Treatment: no treatment exists. However, some antiviral substances, such as acyclovir (Zovirax) can reduce the frequency of appearance of the sores.

Geographical distribution of the microorganism: worldwide

Prevention: use of a condom during sexual relations

Vaccine: not available