Guyana is in the grip of a dreaded dengue epidemic

This year, mosquitoes are proving to be particularly lively. A particularly severe dengue epidemic is affecting Guyana, with an average of 800 new cases reported each week, health authorities announced on Monday, February 12. According to Public Health France, 5,800 cases have been reported in the Amazon department of 300,000 inhabitants since the beginning of 2023, including 2,996 in 2024. Hadn’t heard in twenty years.

“In the Antilles and throughout the Caribbean the epidemic has crossed the line. But for Guyana, it is very recent,” confirmed epidemiologist Antoine Flaholt, director of the Institute of Global Health at the Faculty of Medicine of the University of Geneva, on France 24. .

In its latest bulletin, the Regional Health Agency (ARS) has mentioned 1^er At least 253 patients were hospitalized in February, including ten “admitted to intensive care.” “Four people who tested positive for dengue died, one of which was directly linked to dengue,” ARS indicated.

The regional health agency has opened a dedicated emergency reception at the Cayenne Hospital Center (CHC) for people with symptoms to receive immediate care if needed.

For the moment, the impact on the Guyanese health system remains “relatively limited”. As of early February, the infection had generated only “8 to 10% more activity” for the emergencies at Kourou and Cayenne hospitals.

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An aggressive virus for people with sickle cell disease

The Institut Pasteur indicates on its website that “most infected people have only mild or no symptoms.” In its classic form, dengue fever presents as a “high fever with frequent headache, nausea and vomiting” lasting two to seven days.

But in the most severe cases, endemic in tropical areas, this disease can cause bleeding or shock syndrome that can lead to death. Dengue virus can be very aggressive, especially for people with sickle cell disease.

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“Dengue fever is usually benign (…) It is sometimes called tropical flu but its development is dangerous for certain subjects,” warns Professor Narcisse Elenga at Guyenne la Premier, Head of the Pediatric Department and Head of the Integrative Sickle Cell Center. . at Cayenne Hospital Center. However, in Guyana, according to the Regional Health Monitor, 10% of the population carries the gene that transmits the disease.

“Domestic” mosquitoes in gardens

In tropical and subtropical areas such as Guyana, dengue epidemics are common. They come back every three to five years and usually last 12 to 18 months. Viral waves are more or less intense.

Two of the four existing dengue genotypes (DEN-2 and DEN-3) are circulating in the region at the same time, which may have contributed to intensifying the epidemic, because after being infected by dengue DEN-2, an immune individual, if it is this Once infected with dengue DEN-3, it can be re-infected.

Climatic conditions also contribute to the severity of epidemics. According to the World Health Organization (WHO), dengue fever is increasing worldwide due to climate change. In Guyana, the epidemic was favored by the rainy season, which increased the number of standing water areas and therefore larval breeding sites.

Dengue fever is usually transmitted by the bite of the Aedes mosquito, also known as the tiger mosquito. “These are mosquitoes that don’t travel much, they have a flight radius that only goes up to 70 or 100 meters,” explains Antoine Flaholt, who describes them as ‘domestic’ mosquitoes because they live close to houses. “You grow it in your garden, usually under flower pots in gardens,” the epidemiologist explains sarcastically. “You really need to remove the water from under the saucer, don’t water your plants, try to avoid these small pools of stagnant water that cause swarms of mosquitoes in your direct environment,” he recommends.

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To combat their spread, a monitoring unit bringing together state services and the Territorial Collectivity of Guyana (CTG) was activated on February 6, said Prefect of Guyana Antoine Poussier. An order was signed to remove end-of-life vehicles, which are numerous on roads and “which create breeding grounds for mosquitoes that facilitate the spread of dengue”.

CTG pledged to “increase its human and physical resources” in the field of mosquito control, for which it has competence. Chemical spreading operations are not without side effects. Mosquito control is usually done at night because the released product can cause health problems. In addition, warns the Pasteur Institute that “insecticides can also be used but their widespread use can create a resistance phenomenon in the mosquito population, making them less effective”.

A “promising” Brazilian vaccine

Although there is no specific treatment for dengue fever, vaccines have been developed over the years. But they have not yet been recommended by the French authorities.

Sanofi has developed a vaccine, but “it is not recommended in most cases”, explains Antoine Flahout, adding that it has “proved to be frustrating and complicated for the moment due to adverse effects”. In a report published in January 2019 on the vaccine, Dengvaxia, the highest authority for health, noted that there was an “increased risk of hospitalization and severe dengue” in people who had not been infected with the disease in the past, “especially in young children”.

In Brazil, where 395,103 possible dengue cases and 53 virus-related deaths were reported in the first five weeks of the year, a free vaccination campaign was launched on February 9. Conducted with the Kyudenga vaccine, produced by the Japanese laboratory Takeda, it will begin in children aged 10 and 11 and will gradually be extended to patients up to the age of 14.

This vaccine “has the distinction of being usable by all, but it does not protect against all types of dengue”, we can read on Guyana La Premier.

A third vaccine, currently under study, raises much hope. This is the Brazilian Butatan-DV vaccine, “very promising” according to Antoine Flaholt. A single-dose vaccine will protect against all four types of dengue. Preliminary results of the trial, conducted on 16,235 people in Brazil and started in February 2016, show high efficacy, 90% in people over 18 years old and 77.8% in children over 7 years old. But it should not be marketed before 2025, the time to be examined by health authorities who will decide to give the green light to its marketing.

with AFP