The Asian tiger mosquito also originates from Germany. This country does not yet transmit the dengue virus, but cases of the disease are increasing worldwide due to climate change. Successful trials in Brazil now give hope that the bacteria can help fight the disease.
For some infectious diseases, an increase in the number of cases and the spread of pathogens can be expected due to climate change. Dengue fever is certainly one of these, as a US research group explains. Around 19% of cases in heavily affected countries can already be traced back to the effects of climate change. THE Analyze has now been presented at the annual meeting of the American Society of Tropical Medicine and Hygiene (ASTMH) in New Orleans.
Extremely high numbers of dengue will be recorded in 2024: according to the European health authority ECDC, by September there have been 13 million infections and 8,500 deaths worldwide reported. For comparison: in the entire year 2023, there were six million infections and 6,000 deaths. Brazil, among others, has been severely affected.
Dengue fever is an infectious disease caused by viruses. This can be very painful and is also known as mill fever due to the severe muscle and joint pain. Other typical symptoms include high fever, severe headache, nausea and vomiting. In rare cases, especially in cases of dengue virus reinfection, serious and sometimes fatal outcomes can occur.
The virus is transmitted mainly by the Asian tiger mosquito (Aedes albopictus) and the Egyptian tiger mosquito (Aedes a Egypti), also known as the yellow fever mosquito. In a previous study, researchers found that the number of viruses in mosquitoes in the laboratory is highest at 26 degrees (Asian tiger mosquito) and 29 degrees (Egyptian tiger mosquito). These temperatures therefore represent the highest risk of infection.
“Clear and direct relationship”
The team led by Erin Mordecai of Stanford University in California and Harvard researcher Marissa L. Childs examined the development of dengue infections in Latin America and Southeast Asia and made predictions for the future from the models. The five-member team collected observations of dengue fever in 21 countries in Latin America (from Mexico to Brazil) and Southeast Asia (from Sri Lanka to Indonesia).
There is “a clear and direct relationship between rising temperatures and rising infections,” Mordecai explained. According to the study, with steadily increasing greenhouse gas emissions, the proportion of climate-related dengue cases could increase to around 60% by 2050
On the occasion of ASTMHconference, an Australian research team led by Katie Anders of the World Mosquito Program at Monash University in Melbourne presented an apparently effective measure against the transmission of the dengue virus. By December 2019, scientists had released numerous mosquitoes infected with a naturally occurring mosquito across most of the city of Niterói, near Rio de Janeiro. Wolbachiathe bacteria were infected.
By June 2023, they had expanded the operation to the remaining areas of the city. The bacterium causes mosquitoes to transmit viruses to a significantly lower extent and, according to studies, poses no danger to humans, animals or the environment.
“We have already after the introduction of Wolbachia “We saw in Niterói that the infections practically stopped,” Anders said. And even though there would be a slight increase in 2024, the number of cases was still 90% lower than before the introduction – and in no way comparable to what was happening in the rest of Brazil.
Dengue incidence has fallen to about 84 cases per 100,000 population per year, compared to an average of 913 cases previously. There are similar projects in other places in the world, including Rio de Janeiro, where there is also a program in collaboration with Global mosquito control programme race.
“In Brazil we are there, Wolbachia “From an experimental measure to a cornerstone of the fight against dengue,” says project manager Luciano Moreira. They partnered with the Brazilian government to build a manufacturing plant for Wolbachia-Build mosquitoes that allow them to be used in multiple cities at the same time. With the aim of protecting many millions of people.
Dengue fever is a notifiable disease in Germany. The Robert Koch Institute (RKI) received a report of 953 imported cases in 2023, as recently reported published The ”Epidemiological Bulletin” reports this. The four most frequently cited countries where the respective infection may have occurred were Thailand (275 cases), Indonesia (72), Mexico (66) and India (63).
According to the alarm raised by the World Health Organization (WHO) at the end of last year, the risk of dengue fever cases is increasing in this region.
From January 1 to December 5, 2023, according to WHO information, Italy reported 82 locally transmitted infections, France 43 and Spain 3.
How does the presence of the Asian tiger mosquito indicate a potential dengue outbreak in countries with no current transmission?
Time.news Editor: Welcome to Time.news! Today, we’re exploring an alarming but interesting topic: dengue fever and how climate change is reshaping the landscape of infectious diseases like this one. Joining us is Dr. Marissa L. Childs, a researcher from Harvard University who has conducted extensive studies on the relationship between climate change and the rising number of dengue cases worldwide. Thank you for being here, Dr. Childs!
Dr. Marissa L. Childs: Thank you for having me! It’s a pleasure to be here.
Editor: To start, could you explain the current state of dengue fever globally? What trends are you observing?
Dr. Childs: Certainly! We are witnessing a dramatic rise in dengue cases. In 2024 alone, the European Centre for Disease Prevention and Control reported around 13 million infections and 8,500 deaths. This is a significant increase from the 6 million infections and 6,000 deaths reported in 2023. Our research highlights that about 19% of these cases are attributable to climate change, linking rising temperatures directly to the spread of dengue.
Editor: That’s startling. Can you elaborate on how climate change specifically influences the transmission of dengue fever?
Dr. Childs: Absolutely. The dengue virus is primarily transmitted by the Asian tiger mosquito and the Egyptian tiger mosquito. Studies indicate that these mosquitoes thrive in warmer conditions, with peak viral activity occurring at specific temperatures—26 degrees Celsius for the Asian tiger mosquito and 29 degrees Celsius for the Egyptian mosquito. With global temperatures on the rise, the conditions are becoming increasingly favorable for these mosquitoes to thrive and spread the virus.
Editor: Speaking of the Asian tiger mosquito, I understand it even originates from Germany. How might that affect countries like Germany that currently don’t have a dengue transmission issue?
Dr. Childs: Yes, it’s intriguing but concerning. While Germany hasn’t seen dengue transmission yet, the presence of the Asian tiger mosquito signifies a looming threat. As climate change continues to expand the habitats of these mosquitoes northward, it’s crucial for countries that have so far been unaffected to prepare for potential outbreaks. The shifting climate could change that status at any time.
Editor: In light of these challenges, are there any promising developments in combating the dengue virus?
Dr. Childs: There are indeed hopeful advancements! A notable initiative is the use of the bacteria Wolbachia, which has been introduced in mosquito populations in Niterói, Brazil. This naturally occurring bacterium significantly reduces the ability of mosquitoes to transmit the dengue virus. Research shows that since its introduction, dengue infections in the city have effectively plummeted—by about 90%. The results are encouraging, providing a potentially sustainable method to control the spread of dengue without harming human health or the environment.
Editor: That sounds revolutionary. What do you think the global community should focus on moving forward?
Dr. Childs: First, we need increased investment in research and public health initiatives that address climate change and its impact on infectious diseases. Public awareness is crucial as well—educating people about prevention methods and the importance of controlling mosquito populations can make a significant difference. Lastly, we must collaborate internationally to share successful strategies and adapt them to various regions threatened by dengue and other climate-related diseases.
Editor: It seems imperative that we act urgently. Dr. Childs, thank you for your insights today on this pressing public health issue. Your research is invaluable in understanding how we can combat the threat of dengue fever in an era of climate change.
Dr. Childs: Thank you for having me! It’s been a pleasure discussing these critical topics.
Editor: And thank you to our readers for tuning in. Stay informed and join us next time as we explore more developments in health and environmental science.