Infectologist Warns That Almost 70% of Venezuelan Territory is Endemic for Yellow Fever

Infectologist Patricia Valenzuela warned that almost 70% of Venezuelan territory is endemic for yellow fever, which requires strengthening vaccination and prevention strategies due to the risk of transmission in large areas of the country. By María Iriarte / Radio Fe y Alegría Noticias In an interview with the program Háblame Bajito of Radio Fe y Alegría Noticias, the specialist explained that there are three ecological corridors in Venezuela where the disease circulates in its wild cycle: San Camilo, Sur del Lago, and Guayana. She detailed that the San Camilo corridor is located in the foothills of the states of Apure, Táchira, Barinas, and Mérida, although its area of influence extends to Portuguesa, Cojedes, and Guárico. The Sur del Lago corridor mainly covers the state of Zulia and extends to Falcón, while the Guayana corridor comprises the basins of the Yuruaní, Cuyuní, and Caroní rivers, in Bolívar state, with reach to Amazonas, Anzoátegui, Monagas, Sucre, Miranda, and Guárico. She stressed that this wide geographical distribution necessitates considering vaccination on a national scale, even though campaigns prioritize states where cases have been reported. Yellow fever circulates in Venezuela in its sylvatic cycle Valenzuela pointed out that yellow fever is an acute hemorrhagic viral disease, endemic in several South American and African countries. She recalled that since 2024, South America has been facing an outbreak that began in Brazil and currently has a greater presence in Colombia. It is transmitted by mosquitoes and has two transmission cycles: sylvatic and urban. In the sylvatic cycle, Haemagogus and Sabethes mosquitoes transmit the virus to non-human primates (howler monkeys) which act as reservoirs. Humans can become infected when they come into contact with these areas due to work in rural areas, activities in forests, or tourism. She also clarified that the cases currently reported in Venezuela correspond to this sylvatic cycle and that there has been no urban transmission since 1928. In the urban cycle, the virus is transmitted by the Aedes aegypti mosquito, known as the white-legged mosquito, which also transmits dengue, zika, and chikungunya. "We do not want an urban cycle to be established," warned Valenzuela, adding that for this reason, health education and vaccination are insisted upon. Insufficient vaccination coverage She attributed the resurgence of the disease in the region to the decrease in vaccination coverage, as well as to factors such as migration and deforestation. She noted that the Pan American Health Organization reported a regional vaccination coverage of 72% for 2024, well below the recommended 95%, and that in some Venezuelan municipalities it could be even lower. The specialist said that the yellow fever vaccine is recommended from one year of age up to 59 years. In individuals over 60 years of age, the risk-benefit must be evaluated, especially if they have chronic diseases that weaken the immune system. She also warned that immunocompromised individuals and pregnant women should not be vaccinated, unless a doctor determines otherwise after evaluating each case. She specified that a single dose of the vaccine is sufficient for lifelong protection, as it is scientifically proven that neutralizing antibodies are maintained over the years. In case of traveling to risk areas, she suggested getting vaccinated at least 10 days before the trip. Symptoms, risks, and diagnosis Regarding symptoms, she stated that the disease begins with a sudden onset of high fever, chills, headache, intense muscle pain, and back pain, symptoms that usually appear three to six days after the mosquito bite. In approximately 80% of cases, the disease progresses to recovery, but about 15% of patients may develop a severe or toxic phase, characterized by jaundice (yellowing of the skin and mucous membranes), liver and kidney failure, as well as hemorrhages. Of these severe cases, up to 50% can be fatal. The diagnosis of yellow fever can be made through molecular detection of the virus via a real-time PCR test, available at the Instituto Nacional de Higiene Rafael Rangel in Caracas, although it can also be performed at the Instituto de Medicina Tropical, from where samples are sent for confirmation to specialized laboratories. When there is suspicion in the interior of the country, health centers must notify the epidemiology system and send the sample to the National Institute of Hygiene for diagnostic confirmation. Treatment and prevention The specialist indicated that there is no specific antiviral for yellow fever, so treatment is based on symptom management. Patients must remain hospitalized in isolation and use mosquito nets to prevent mosquitoes from transmitting the virus to other people. Treatment measures include adequate hydration and the use of acetaminophen or paracetamol for fever, while non-steroidal anti-inflammatory drugs should be avoided as they can promote bleeding. She also urged taking measures to reduce the risk of contagion, such as using repellent, wearing light-colored long-sleeved clothing, using mosquito nets, eliminating mosquito breeding grounds, and keeping areas where water can accumulate clean. Finally, she highlighted that controlling the disease requires joint work between health authorities and communities.