A rare imported disease in France

Cholera is an acute gastrointestinal infection caused by ingesting water or food contaminated with Vibrio cholerae bacteria of the toxin-producing serogroups O1 and O139 (cholera vibrios).

Today, public and personal sanitation and hygiene measures have led to the eradication of cholera in France (excluding French Guiana and Mayotte, where sporadic and limited outbreaks were reported in the 1990s and 2000s). In mainland France, cholera, which is a notifiable disease, is in fact a rare imported disease. Symptomatic cases of cholera are primarily linked to the consumption of contaminated food or beverages abroad.

Early reporting of suspected and confirmed cases, as well as notification of confirmed cases, occurs as soon as a single case is identified. This enables the prompt management of imported cholera cases. Between 0 and 2 cases of cholera have been reported annually in France since 2000; these involve travelers returning from endemic areas. This is a low figure and one that is decreasing.

Although rare in France, cholera can cause severe digestive symptoms and dehydration. Even though the risks of transmission and an epidemic are very limited within France, Santé publique France’s epidemiological surveillance requires the early reporting of cases as soon as this infection is suspected in order to prevent its spread.

Human-to-human and environmental transmission

Humans are the primary reservoir of cholera. However, in certain regions, the environment can also serve this role, leading to the endemic circulation of cholera vibrios. Cholera is linked to the ingestion of contaminated water or food. The bacteria, or cholera vibrios, secrete the cholera toxin in the intestine, which causes the loss of water and electrolytes (up to 15–20 liters per day). Large volumes of watery stools spread the bacteria into the environment and facilitate fecal-oral transmission.

High population densities, combined with poor environmental hygiene, promote the emergence and spread of cholera epidemics.

Prevention through hygiene and vaccination

When basic hygiene rules are followed, the cholera vibrio is not highly contagious. Proper water chlorination and basic hygiene measures are generally sufficient to prevent infection.
When traveling to these endemic areas, adhering to hygiene measures (food safety by consuming cooked and hot food, bottled water with a sealed cap, avoiding ice cubes, and handwashing) remains the best form of prevention.

There is no active vaccine against Vibrio cholerae serogroup O139. However, healthcare workers going to work with patients or in refugee camps during an epidemic may receive the oral cholera vaccine (against various strains of Vibrio cholerae O1 and a subunit B of the recombinant cholera toxin) (2 doses one week apart for adults and 3 doses one week apart for children aged 2 to 6 years).

Severe intestinal symptoms

The incubation period for cholera is short, ranging from a few hours to five days.

Most people infected with Vibrio cholerae have few or no symptoms, although the bacterium can be found in their stool for one to two weeks. When illness does occur, 80 to 90% of cases are mild or moderately severe, making it difficult to distinguish them clinically from other types of acute diarrhea.

Fewer than 20% of patients develop the full range of typical cholera symptoms, including signs of moderate to severe dehydration: violent, profuse “rice-water” diarrhea and vomiting, without fever.

Without treatment, death occurs within 1 to 3 days, due to cardiovascular collapse in 25 to 50% of cases. Mortality is higher among children, the elderly, and immunocompromised individuals.

The diagnosis of cholera is clinical and laboratory-based. It relies on the detection of V. cholerae serogroup O1 or O139, which produces cholera toxin, in a patient’s stool. If a cholera vibrio strain is suspected, contact the National Reference Center for Vibrio and Cholera immediately for typing and confirmation of the diagnosis: https://www.pasteur.fr/fr/sante-publique/cnr/les-cnr/vibrions-cholera

Treatment based on rehydration

Treatment for cholera consists primarily of replacing water and electrolytes lost through the digestive tract. Depending on the severity of dehydration, rehydration is administered orally or intravenously. The patient’s condition improves rapidly (within a few hours), and recovery occurs within a few days. There are no long-term effects. Antibiotic therapy may be useful in certain severe cases, but multidrug-resistant strains may emerge.

Endemic circulation in South Asia

Cholera regularly causes epidemics in developing countries, where it occurs in an endemic and/or epidemic pattern, depending on the country.

Since 1961, the world has been experiencing the seventh cholera pandemic, caused by the O1 serogroup of Vibrio cholerae.

Cholera has, in fact, been endemic to the Indian subcontinent for several centuries. Cholera spread from 1817 throughout Asia, the Middle East, and parts of Africa during the first cholera pandemic. Subsequent pandemics also originated in Asia and were facilitated by improvements in transportation. The seventh pandemic, which originated in Indonesia in 1961, affected Asia in 1962, the Middle East and parts of Europe in 1965, Africa in 1970, and South America in 1991.
On the island of Hispaniola, an epidemic has been ongoing since the emergence of V. cholerae serogroup O1 in Haiti in 2010.
Today, Africa and Asia are the two regions most affected by cholera. The disease is spreading there. The epidemic reported in Yemen since 2016 is the largest ever documented.

In 1992, a strain of Vibrio cholerae belonging to the new serogroup O139 emerged in India and Bangladesh. Since then, it has caused epidemics in several Asian countries and could one day trigger an eighth pandemic. Cholera was the first disease to be subject to international notification (since 1892).