There are many challenges in the prevention and control of dengue fever in Latin America. Scan the code and read the mobile version.

From the beginning of this year to the beginning of April, the number of dengue fever cases in America, especially in Latin America and the Caribbean, surged. More than 4.25 million people were confirmed to be infected with dengue virus, and more than 1,400 people died, three times that of the same period last year. Local medical and health professionals told CCTV reporters that the dengue fever epidemic in Latin America continued to spread due to multiple reasons. Although the response measures of Latin American governments and health organizations have achieved certain results, the epidemic prevention and control still faces many challenges.

Dengue fever cases surge in Latin America

Dengue fever is an acute infectious disease caused by dengue virus, which is mainly transmitted by mosquitoes and is prevalent in tropical and subtropical regions. Typical symptoms include persistent fever, headache, muscle pain, joint pain, etc., and can be fatal in severe cases.

The latest epidemiological alert issued by the Pan American Health Organization on April 9 this year shows that in the first 12 weeks of 2024, more than 4.25 million cases of dengue fever were reported in the Americas, with 1,423 deaths, three times that of the same period in 2023. Among them, Brazil, Argentina and Paraguay have the most serious epidemics, accounting for the vast majority of dengue infection cases and deaths in this area.

According to the data released by the Brazilian Ministry of Health on April 8, the number of dengue fever cases recorded in this country has reached 2,747,643 (including suspected cases) and 1,078 deaths. As of early April, the number of deaths from dengue fever in Brazil this year has reached the third highest since the epidemic was recorded in 2000.

According to the report released by the Ministry of Health of Argentina on April 7, 215,885 cases of dengue fever have been diagnosed in Argentina since 2024, and the prominent feature of this dengue epidemic is "continuous occurrence". In 19 of Argentina’s 24 provinces, dengue virus has spread locally. In addition, dengue fever deaths have occurred in all ages, with the highest mortality rate among people over 80 years old.

According to data released by the Ministry of Health of Paraguay on April 5, there were 4,848 new cases of dengue fever in the country in the past three weeks, and the most seriously affected people were children aged 5 to 9. At present, 83% of the country’s territory has been affected by dengue fever.

Other countries in Latin America are also more or less affected by the dengue epidemic. At present, dengue fever is still at the peak of transmission, and the epidemic continues to spread in this area.

△ Main vector of dengue fever: Aedes aegypti

Multiple factors lead to the rapid spread of dengue fever in Latin America.

According to the analysis of local disease control experts, natural factors are an important reason for the rapid spread of dengue fever in Latin America, especially the climate change brought about by global warming has promoted the increase of dengue cases. Jarbas barbosa, head of Pan-American Health Organization, said in an interview with the general station reporter that the continued spread of dengue fever was mainly due to El Niñ o phenomenon and climate change, especially the high temperature and intermittent rainfall brought by El Niñ o phenomenon led to the accelerated reproduction of Aedes aegypti, which further accelerated the spread of the epidemic.

Relevant research shows that the number of dengue cases tends to increase in the year of El Niñ o phenomenon. In the past 15 years, there have been five El Niñ o phenomena in Brazil in summer, and the number of people infected with dengue fever has exceeded 1 million each time. Kleber Luz, an expert on dengue infectious diseases at the Pan American Health Organization, said that the El Niñ o phenomenon caused the sea water temperature to rise, which led to an increase in the number of Aedes aegypti, an increase in reproductive capacity and an increase in life expectancy. With the climate change, the increase in the number of Aedes aegypti will not only increase the number of dengue cases, but also expand the area affected by dengue fever.

Climate change has also aggravated the spread of dengue fever. Paul Lotufo, an expert on dengue fever prevention and control, told the CCTV reporter that climate change is a major reason for the spread of dengue fever. Around 1986, Aedes aegypti mainly existed in Rio de Janeiro in the southeast of Brazil, and since the 1980s, Aedes aegypti has moved southward year by year, resulting in cases in places where dengue fever did not occur before.

Antonio Bandala, an infectious disease expert in Brazil, said that a climate corridor starting from central and western Brazil and running through the southeast and southwest of the country had an impact on the dengue epidemic in Latin America. The climate corridor is characterized by high temperature, frequent fluctuations and heavy rainfall, which creates conditions for the massive reproduction of Aedes aegypti and increases the number of dengue cases in Brazil, Paraguay and Argentina.

Social factors are another reason for the rapid spread of dengue fever in Latin America. The rapid population growth and mobility, the lack of urban infrastructure-related services and the lack of control measures have led to a large number of Aedes aegypti breeding. In 2010, Brazil had 191 million residents. In 2022, the number of residents in the country reached 203 million. Verdo Naviganster, a professor of epidemiology at the University of Brasilia, pointed out that it is difficult for Aedes aegypti to fly long distances. Areas with high urbanization and dense population are conducive to mosquito predation, and the increase in population also leads to an increase in the number of susceptible people.

Experts also said that the accelerated population movement is also one of the reasons for the continuous outbreak of dengue fever in Latin America. In addition, inadequate urban infrastructure services, including sewage discharge, urban cleaning and garbage disposal, have also led to the spread of dengue fever. The data shows that the total number of households in Brazil is 74 million, of which nearly 9 million cannot use the conventional water supply network; Nearly 7 million people face the problem of insufficient water supply. According to data collected by the Brazilian Institute of Geography and Statistics from 2013 to 2022, 22 million people in Brazil lack sewage collection facilities in their daily lives. Unstable infrastructure increases the probability of sewage accumulation, and mosquitoes can breed in large numbers.

Latin American governments have different attitudes towards the use of vaccines.

In the face of the epidemic, Brazil, Argentina, Paraguay and other Latin American countries have taken a number of prevention and control measures in vector control, vaccination, publicity and prevention. The analysis pointed out that because the current vaccine research and development is in the initial stage, different Latin American countries hold different attitudes towards the use of vaccines, but the countermeasures taken to eliminate mosquito breeding environment are the same.

The Brazilian government plans to vaccinate the public with 6.5 million doses of dengue vaccine this year, giving priority to adolescents aged 10 to 14 who have the highest proportion of hospitalized cases. In February this year, more than 500 cities in Brazil launched a large-scale dengue vaccination, and the government provided free vaccination for 3.2 million people. On March 29th, the Brazilian Ministry of Health announced that residents of 165 cities would be vaccinated against dengue fever based on the spread rate of dengue fever, and on March 31st, the economic center of Sã o Paulo State was included in the list of dengue vaccination areas. The vaccine is divided into two doses, and the interval between the two vaccinations is three months. The vaccine is delivered by the Brazilian Ministry of Health to the state government, and the local municipal department is responsible for drawing up the vaccination time.

△ Rio de Janeiro, Brazil vaccinates children against dengue fever

Brazil’s Ministry of Health standardized and strengthened the monitoring and reporting system of dengue fever, so as to ensure the timely grasp of the epidemic situation and adjust the public health response measures accordingly. At the same time, the Ministry of Health coordinates the establishment of dengue emergency operation centers in various places to coordinate epidemic prevention actions and monitor and analyze the epidemic situation. Rio de Janeiro and other states declared a state of public health emergency and opened specialized treatment centers for dengue fever in order to relieve the pressure on hospitals. The Brazilian government has also vigorously promoted anti-mosquito measures, publicized the people through various channels such as the media, raised public awareness of the epidemic disease, guided the people to prevent dengue fever in their daily lives, tried to eliminate the stagnant water environment suitable for Aedes mosquitoes to breed, and sought medical attention in time when symptoms appeared.

Argentine authorities launched "fumigation operations" in different regions to fight mosquitoes. Since November 2023, the Argentine government has provided dengue vaccine to the public, but at present, the vaccine is still a prescription drug, and the cost is about 70,000 Argentine pesos (about 590.58 yuan), while providing a 40% discount for some susceptible people. From January to February, 2024, the provinces of Misiones in the northeast and Salta in the northwest of Argentina successively launched free dengue vaccination programs for the 20-40 age group. In March, the Ministry of Health of Argentina issued a proposal for prevention and control of dengue fever, urging people to strengthen protection, guiding people to eliminate mosquito breeding sites, using regular insect repellents, identifying dengue fever symptoms and seeking medical treatment in time. On March 26th, the first meeting of the Argentine Federal Health Committee on the prevention and control of dengue fever was held in Buenos Aires, the capital, to discuss the measures of joint action of epidemic prevention and control and the vaccination plan.

In addition, in response to the epidemic, the Ministry of Health of Paraguay has taken public health measures, provided vaccination services and carried out fumigation operations in many places. At the same time, guide the public to eliminate stagnant water, prevent mosquito breeding, and publicize and emphasize avoiding mosquito bites for susceptible people, especially children, and seek medical advice in time when relevant symptoms appear. Due to the dengue fever epidemic, the Peruvian government declared a 90-day health emergency in 20 regions of the country on February 27th. In this state, the government can provide more financial budget to support epidemic prevention and control measures. On April 5, the Ministry of Health of Peru announced that fumigation activities would be carried out in eight regions of the country from now on, aiming at eliminating adult Aedes aegypti and its larvae to curb the spread of dengue fever.

Unlike Brazil’s large-scale free vaccination against dengue fever and active vaccine development, Argentina is more cautious about vaccination. Panama’s Ministry of Health recently said that considering the actual effect of the vaccine in the prevention and control of dengue fever, the country does not plan to launch a large-scale vaccination. Barbosa, the head of the Pan American Health Organization, told the general station reporter that the current use of vaccines has no obvious effect on cutting off the transmission chain. On the one hand, the current vaccines need to be vaccinated with two injections, with an interval of three months, which is of little significance for quickly cutting off the transmission chain. On the other hand, the current supply of vaccines is limited and can only partially meet the vaccination needs of specific people.

△ Fumigation activities in Brasilia, the capital of Brazil

Pan American Health Organization (PAHO) calls on all countries and regions in the region to support the prevention of dengue fever and intensify efforts to reduce mosquito breeding sites, which is the main measure to prevent the spread of dengue fever at present. Because vaccine research and development is still in the early stage, barbosa emphasized the importance of health system construction, vector control and international cooperation in an exclusive interview with the reporter from the General Station, and called on all countries to strengthen the training of medical staff and strengthen the construction of primary health institutions, so as to diagnose and treat as soon as possible and prevent deaths. Barbosa said that the Pan American Health Organization (PAHO) is providing technical support to member countries to help them strengthen the surveillance system, monitor the epidemic development in each region and determine the serotype of dengue virus that is spreading. In addition, the organization has provided training for more than 300,000 medical staff on the clinical treatment of severe cases of dengue fever.

Dengue fever prevention and control faces multiple challenges

Although the current prevention and control measures have achieved certain results, the dengue fever epidemic in Latin America continues to spread.

Barbosa said that artificial water storage is the biggest challenge for dengue prevention and control. In slums all over Latin American cities, all water storage containers of residents may become mosquito breeding grounds. Countries in southern Latin America may reach the peak of dengue fever transmission in April, while countries in northern Latin America need to prepare for the possible dengue fever epidemic season.

Lotufo said that compared with Paraguay and Argentina, Brazil is more effective in curbing the spread of Aedes mosquitoes, but the control ability of local governments still needs to be improved. Mosquito control is the most important measure to prevent and control dengue fever, and vaccination has limited effect in reducing the severity and mortality of cases.

In the face of dengue fever, the prevention and control measures in Latin America are still insufficient. On the one hand, some experts said that people’s awareness of epidemic prevention is still relatively weak. The chairman of Brazil’s National Health Sector Joint Committee said that until a month or two ago, people still paid insufficient attention to the dengue fever epidemic. On the other hand, some people think that the government’s prevention and control measures have limited effect. Ricardo Guttler, an Argentine health expert, said that since the outbreak of dengue fever in Argentina, the national and local governments have gradually withdrawn from the prevention and control of dengue fever. The Argentine Ministry of Health issued a statement on April 2, saying that the government has not yet had enough evidence to prove the effectiveness of dengue vaccine, and it is impossible to include it in the national vaccination plan and carry out free vaccination for the people.

Experts said that there is no specific antiviral drug for dengue fever at present, and only symptomatic treatment measures can be taken. The principle of treatment is early detection, early diagnosis, early treatment, early mosquito prevention and isolation, and early diagnosis and timely treatment of severe cases are the key to reduce mortality.