Climate emergency multiplies cholera outbreaks as vaccines run short | future planet

The world is experiencing an emergency of cholera outbreaks never seen since there were vaccines. In 2022 alone, this disease emerged in 30 countries against an annual average of 20 epidemics in the last five years, as warned by the World Health Organization (WHO), which also points out that mortality has tripled. The causes are many, but researchers and experts agree on this global temperature increase due to climate change plays a fundamental role in the intensification of cholera cases, together with forced migrations and conflicts. All of this is taking place against a backdrop of vaccine shortages, which has made it necessary to reduce the doses administered in these outbreaks from two to one.

“Global rising temperatures and extreme weather events favor the reproduction of the bacillus that causes cholera. Droughts reduce water sources and increase the risk of contamination, while floods destroy drainage systems, benefiting the contagion. Add to this climate migration and conflicts, we are facing the perfect storm, with millions of people living in refugee camps, with limited access to health and poor sanitation conditions,” says Miriam Alía, Head of Immunization and Response to the epidemics of Médecins Sans Frontières (MSF).

Cholera is an old knowledge of humanity, an acute diarrheal disease caused by the ingestion of food and above all water contaminated by the bacillus Vibrio cholerae. Currently endemic in 47 countries of the world, the least developed, where sanitation systems are more precarious, it is capable of killing in just four hours. It has a mortality rate of up to 50% without access to treatment, basically oral or intravenous hydration for the most severe cases, but which is reduced to 1% if there is early diagnosis and health care. The best news is that there is a vaccine, and it’s relatively easy to administer.

[El cólera] It has a mortality rate of up to 50% without access to treatment, basically oral or intravenous hydration for the most severe cases, but it drops to 1% if there is early diagnosis and health care.

Haiti is one of the affected countries. The epidemic began at the end of September and has already reached a hundred deaths and practically 10,000 cases, with a large outbreak in the capital, Port-au-Prince. The rate of expansion is alarming. Cholera had not been present in Syria for 15 years, but made a strong reappearance last September, reaching 13,000 cases and 60 deaths. In Malawi it is much more lethal: the outbreak has spread to all 29 districts of the country, causing 10,300 cases and 300 deaths. This is due to the passage of Tropical Storm Ana and Cyclone Gombe in January and March of this year, which caused extensive flooding and the displacement of thousands of people who now have little access to water, services sanitation and adequate hygienic conditions. . Lebanon, Kenya, Nigeria or Bangladesh are other countries with active outbreaks.

Last October, Tedros Adhanom Ghebreyesus, director of the WHO, sounded the alarm: “We are not only seeing more outbreaks, but more deadly outbreaks. The data we have, which is limited, shows that the average death rate so far this year is nearly three times that of the past five years.” There is no doubt in his view: “Extreme weather events, such as floods, cyclones and drought, further reduce access to drinking water and create the ideal environment for the spread of cholera”. This disease, he added, “feeds on poverty and conflict, but is now exacerbated by climate change”.

Extreme weather events such as floods, cyclones and droughts further reduce access to clean water and create an ideal environment for cholera to spread

Tedros Adhanom Ghebreyesus, director general of the World Health Organization (WHO).

The cholera vaccine “is oral, like the polio vaccine, and can last up to 14 days outside the cold chain,” says Alía. However, the current production for both preventive needs and active outbreaks is not sufficient. In 2022 it was expected to produce about 36 million doses, most of them for the so-called reactive or preventive vaccination. However, the “unprecedented” appearance (according to the WHO) of outbreaks in around thirty countries has forced more doses to be allocated to emergencies. For this reason, on October 19, the International Coordination Group (ICG), which coordinates this immunization, decided to reduce the outbreak response doses from two to one, which shortens the immunity time. “The single-dose strategy has been shown to be effective in responding to outbreaks, although evidence on the exact duration of protection is limited. It appears to be much lower in children,” says the ICG.

Virtually all cholera vaccine production is concentrated in two plants located in India and South Korea, but they are at capacity limits. “We will not have an increase in production for at least the next two years and the buffer stock the current is not enough”, explains Alía, who insists that, in any case, preventive vaccination is only one pillar of the fight against this disease, “the cheapest and most effective”, but must be accompanied by measures such as improving health systems Some countries that had planned to immunize their at-risk population had to delay these plans to deal with outbreaks, such as Nigeria, Cameroon or the Democratic Republic of Congo (DRC).

The emergence of epidemics due to climate change This represents a major setback for the strategy defined by the Global Task Force on Cholera Control (GTFCC), whose goal was to reduce cases by 90% by 2030 through preventive vaccination in the 47 countries where this disease is endemic. More than half of the production went to three African countries, Ethiopia, Nigeria and the DRC, which are now concentrating their efforts on tackling the emergency.

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