The time from the moment of exposure to an infectious agent until signs and symptoms of the disease appear is called as incubation period. The incubation period vary, depending on the type of infection.
The infectious period is the period where the infection can be transmitted from one person to another. Infectious period is not necessarily the same as the incubation period.
What is Listeria Incubation Period?
Listeria infection is cause by the organism Listeria monocytogenes. It is a rare disease but high number of deaths has been reported due to listeria infection. The incubation period of Listeria monocytogenes is longer than the other foodborne infections and varies according to the clinical presentation of the disease. The overall median incubation period of invasive listeriosis was 8 days (range from 1–67 days) and differed significantly by clinical form of the disease. Central nervous system infections and bacteremia incubation period is 14 days. Pregnancy-associated case the incubation period is 6 weeks. For gastroenteritis cases, the median incubation period is 24 hours (range from 6 to 240 hours). The exact incubation period of listeriosis remains controversial due to the fact it affects a large variety of foods, so hard to find the exact food source. Also the bacteria can survive in low temperatures for a long time, so the contaminated food can be eaten on several occasions and the exact date of infection cannot be determined.
What is Listeriosis Infection?
Listeroisis is a foodborne bacterial infection with a low incidence but with a high case fatality rate. It is caused by the bacteria Listeria monocytogenes. It is usually a rare disease with 0.1 to 10 cases per 1 million people per year depending on the countries and regions of the world. Although the number of cases of listeriosis is low, the high rate of death associated with the infection makes it a public concern.
Unlike the other common foodborne diseases, Listeria monocytogenes survive and multiply at low temperature usually found in refrigerators. It’s destroyed by heat. Infection is caused by eating contaminated food with L. monocytogenes. Infection can also be transmitted from the pregnant women to the fetus. The infection is potentially fatal in the fetus, newborn babies, elderly people and immunocompromised adults.
It causes invasive listeriosis with central nervous system involvement (meningitis, meningoenchephalitis) and bacteremia. It also causes gastroenteritis.
L. monocytogenes are ubiquitous in nature and found in soil, water and in the animal digestive system. Vegetables can be contaminated through soil or the use of manure as fertilizer. L. monocytogenes is commonly seen in ready-to-eat food. These processed foods can be contaminated during the processing and the bacteria can multiply to dangerous levels during distribution and storage.
What Is The Incubation Period of Listeria Monocytogenes?
Unlike the other foodborne disease like Salmonella infection the incubation period of Listeria monocytogenes can be long.
Incubation period for listeriosis varies according to the clinical presentation of the disease. Much longer incubation period was observed with pregnancy associated cases than for cases with other clinical forms.
- The overall median incubation period of invasive listeriosis was 8 days (range from 1–67 days) and differed significantly by clinical form of the disease.
- Central nervous system infections and bacteremia incubation period is 14 days.
- Pregnancy-associated case the incubation period is 6 weeks.
- For gastroenteritis cases, the median incubation period is 24 hours (range from 6 to 240 hours).
However, the exact incubation period of listeriosis is still in a controversial situation because an exact date cannot be accurately taken into account from the patients who were infected with Listeria monocytogenes due to several factors.
- Listeria monocytognes contaminate a large variety of foods, which makes it difficult to find the exact food source of the infection.
- As the incubation period is long and variable, the food products consumed during that long period should be taken into account.
- The products contaminated by Listeria monocytogenes can be kept for a long time (several days or weeks) and these can be consumed on multiple occasions, therefore the exact date of infection cannot be determined. This makes it difficult to gather data on incubation period referring to single exposure.
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