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 in Rio de Janeiro, where there is also a programme 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. In Germany itself, no cases of such an infection are known. According to the RKI, local climatic conditions are “not yet very suitable for broadcasts”.
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How effective is the Wolbachia bacteria method in reducing dengue infections in high-risk areas?
Interview between Time.news Editor and Dr. Erin Mordecai, Stanford University
Time.news Editor: Welcome, Dr. Mordecai! It’s a pleasure to have you here today. Your recent research on dengue fever and its relation to climate change has captured global attention. Can you start by explaining how rising temperatures are influencing the spread of dengue fever?
Dr. Erin Mordecai: Thank you for having me! Our research illustrates a clear and direct relationship between rising temperatures and increasing dengue infections. With higher temperatures, particularly around 26 to 29 degrees Celsius, the mosquito vectors responsible for transmitting the dengue virus thrive and become more virulent. Essentially, as the climate warms, the conditions become more favorable for these mosquitoes, leading to a rise in cases.
Time.news Editor: That’s concerning. Your findings suggest that up to 60% of dengue cases may be climate-related by 2050. What do you think this means for global public health, especially in regions like Latin America and Southeast Asia?
Dr. Erin Mordecai: It highlights a critical public health challenge. Regions like Latin America and Southeast Asia, which already experience high incidences of dengue, could see exacerbated outbreaks. This scenario emphasizes the urgent need for proactive measures, both in terms of controlling mosquito populations and enhancing public health infrastructure to manage outbreaks when they occur.
Time.news Editor: Speaking of managing outbreaks, I understand that there’s ongoing research and initiatives using the Wolbachia bacteria to tackle dengue. Can you elaborate on this approach and its effectiveness?
Dr. Erin Mordecai: Absolutely! The Wolbachia bacteria, when introduced into mosquito populations, significantly lower their ability to transmit the dengue virus. Programs, like the one in Niterói, Brazil, have shown impressive results—dengue infections there dropped by 90% after the introduction of Wolbachia-infected mosquitoes. This method poses no risk to humans or the environment, making it a promising tool in the fight against dengue.
Time.news Editor: Fascinating! With the alarming rise in cases and the impact of climate change, what steps should be prioritized on a policy level to combat this issue?
Dr. Erin Mordecai: We need a multifaceted approach. First, there must be increased investment in vector control strategies like Wolbachia. Additionally, improving surveillance systems for rapid response to outbreaks is critical. Lastly, addressing climate change at a systemic level is vital—we must reduce greenhouse gas emissions to prevent further increases in temperature and the consequent rise in dengue cases.
Time.news Editor: You mentioned reduced infections in areas implementing these strategies. Could you share more about the overall impact of these interventions on public health in Brazil?
Dr. Erin Mordecai: Yes, the impact has been significant. In Niterói, the incidence of dengue has decreased to about 84 cases per 100,000 population per year, compared to 913 cases before Wolbachia was introduced. This massive reduction not only saves lives but also alleviates the burden on healthcare systems. The groundwork laid in Brazil could serve as a model for other regions struggling with dengue and similar mosquito-borne diseases.
Time.news Editor: As we look to the future, what gives you hope in the battle against dengue amidst rising temperatures and climate challenges?
Dr. Erin Mordecai: I’m optimistic because we’re seeing real, effective solutions being implemented. Programs like Wolbachia show that we can use innovative approaches to manage these diseases effectively. Furthermore, the awareness around the link between climate change and public health is growing, leading to more people advocating for policies that promote sustainability and health. Collectively, this shift could significantly impact the fight against dengue and similar diseases.
Time.news Editor: Thank you, Dr. Mordecai, for your insights and the important work you’re doing. It’s clear that addressing dengue requires cooperation, innovation, and urgency. We appreciate you sharing your expertise with us today!
Dr. Erin Mordecai: Thank you for having me! It’s crucial we keep the conversation going about these challenges and the solutions ahead.