Chikungunya in Guangdong is just a microcosm
Starting from June 2025, multiple regions in Guangdong reported local cases of chikungunya. This is a viral febrile illness caused by the chikungunya virus, with symptoms including high fever, rash, headache, and severe joint pain, which can last for weeks or even months in severe cases. Although the mortality rate is low, its prevalence and the degree of suffering should not be ignored.
The disease was first discovered in Tanzania in 1952, and the name "Chikungunya" means "to bend" in the local language, vividly describing the posture of patients who bend over due to joint pain. It is primarily transmitted by Aedes albopictus and Aedes aegypti mosquitoes, both of which are widely distributed in Guangdong, especially in urbanized suburban areas with standing water.
This outbreak in Guangdong is not the first occurrence of related cases, but the signs of local transmission indicate that the virus may have breached the "imported" defense line. This also serves as a reminder that mosquito-borne viruses are no longer distant tropical diseases; they have become a real threat in our vicinity.
This event is not only a warning to the public health system but also prompts us to reflect: what profound diseases and disasters have mosquitoes brought throughout human history?
Malaria: The "King's Plague" that has been hard to eradicate for thousands of years
Malaria is one of the oldest and most destructive mosquito-borne diseases. It is a parasitic disease caused by Plasmodium and transmitted by Anopheles mosquitoes. Symptoms include periodic fever, chills, headache, and anemia, with severe cases leading to complications in the brain and even death.
Some scholars speculate that traces of malaria existed as early as the time of the ancient Egyptian pharaohs. Hippocrates, the father of ancient Greek medicine, also described symptoms of "intermittent fever." In China, similar descriptions can be found in the Eastern Han Dynasty's "Treatise on Febrile and Miscellaneous Diseases."
More importantly, malaria is not limited to medical history; it has profoundly influenced politics and warfare. Part of the reason for Napoleon's failure in his African expedition was the rampant malaria; the initial attempts by the United States to build the Panama Canal were also thwarted by malaria and yellow fever caused by mosquitoes.
Even under modern medical conditions, malaria remains a significant challenge to global public health. According to the World Health Organization, there were approximately 240 million cases of malaria worldwide in 2023, resulting in over 600,000 deaths, the vast majority of which were concentrated in sub-Saharan Africa.
Although vaccines, medications, and insecticide measures continue to improve, malaria has not completely disappeared from the Earth due to the strong adaptability of mosquitoes and the increasingly serious issue of drug resistance. This is why mosquitoes are always listed as humanity's "number one enemy."
Yellow fever and dengue: Invisible killers in the process of urbanization
If malaria was prevalent in agricultural societies, then yellow fever and dengue are new "companion diseases" in the modern process of urbanization.
Yellow fever is an acute viral hemorrhagic fever caused by the yellow fever virus, which first appeared in Africa and later entered South America through the slave trade. During the period of Western colonial expansion in the 18th and 19th centuries, yellow fever caused massive deaths in port cities such as Havana and New Orleans. It is transmitted by Aedes aegypti mosquitoes and has a high fatality rate, with some severe patients experiencing jaundice, internal bleeding, and even organ failure.
Similarly, dengue is the most widely spread viral disease transmitted by mosquitoes today. Caused by the dengue virus, it is spread by Aedes albopictus and Aedes aegypti mosquitoes. Patients experience high fever, rash, and joint pain, with severe cases potentially leading to dengue hemorrhagic fever and dengue shock syndrome.
The spread of dengue is closely related to modern urban development. Water accumulation in bottles, flowerpot trays, and discarded building materials can all become breeding grounds for mosquitoes. Due to its rapid transmission, complex symptoms, and lack of specific treatment, dengue has become a significant public health issue in many countries in Asia and Latin America each year.
In recent years, southern cities in China have also frequently experienced outbreaks of dengue fever. For example, in 2014, Guangzhou reported over 40,000 cases of dengue fever, setting a historical high. This indicates that against the backdrop of climate warming and urban expansion, mosquito-borne viruses are continuously "moving north."
West Nile virus and Zika virus: From "exotic tropical diseases" to global alarms
In addition to traditional diseases, some emerging viruses have also entered the global spotlight due to mosquito transmission in recent years. The most typical examples are the West Nile virus and the Zika virus.
The West Nile virus was initially endemic only in Africa and the Middle East, but after its first discovery in the United States in 1999, it spread rapidly. It is transmitted by Culex mosquitoes, with birds as the main hosts, but humans can be "accidentally injured" after being bitten by mosquitoes. Most infected individuals are asymptomatic, but a small number can develop severe complications such as meningitis and encephalitis, and even death.
The impact of the Zika virus is even more social. The virus was relatively "mild" in Africa, but after a large-scale outbreak in Brazil in 2015, a close association was found between it and microcephaly in newborns. This discovery shocked the world and made the Zika virus a public health emergency.
The mosquitoes that spread the Zika virus are also Aedes aegypti, sharing "transportation" with dengue, yellow fever, and chikungunya. These mosquitoes are active during the day, prefer urban habitats, and reproduce rapidly. Their global distribution range is also continuously expanding, giving these viruses a higher potential for transmission.
The outbreak of the Zika virus not only changed people's perception of "mosquito-borne viruses" but also prompted several countries to implement stricter mosquito control and travel warning policies.
Ecological and social factors behind the "most deadly animal"
When discussing mosquito-borne diseases, it is essential to consider the complex interaction between the adaptability of mosquitoes in the ecosystem and human activities.
There are approximately 3,500 known species of mosquitoes globally, with the main ones that transmit human diseases concentrated in the Anopheles (malaria), Culex (Japanese encephalitis, West Nile), and Aedes (dengue, Zika, yellow fever) genera. The reasons these mosquitoes are difficult to control include:
Short breeding cycle: One generation can be completed in 7-10 days;
Diverse breeding sites: Even water accumulated in bottle caps can serve as breeding grounds;
Varied activity times: Some are nocturnal, while others are active during the day;
Urban ecology favors their survival: high temperatures, high humidity, and dense buildings.
At the same time, human behaviors also provide fertile ground for the spread of mosquito-borne diseases:
Frequent global travel and trade: Viruses can "board a plane" and travel abroad within hours;
Rapid urbanization but lagging infrastructure: Poor drainage systems and excessive water accumulation;
Climate warming: Increases mosquito breeding efficiency and expands suitable areas.
For example, recent studies have pointed out that as summer temperatures rise in some northern cities in China, the activity range of Aedes mosquitoes has gradually moved north to the Yellow River basin. This means that diseases like dengue and chikungunya, originally "southern diseases," may also become public health challenges in the north.
Historical experiences and future directions in mosquito control
In the long-standing struggle between humans and mosquitoes, control methods have evolved from primitive physical barriers to today's integrated prevention and control. Historical experience shows that single methods are often ineffective, and comprehensive management is the right path.
Environmental management: Eliminating standing water containers and ensuring smooth drainage is the most basic and effective method.
Chemical control: Using insecticides, mosquito coils, and electric mosquito swatters, but facing the risk of resistance.
Biological control: Introducing mosquito-eating fish and releasing male mosquitoes carrying Wolbachia bacteria to disrupt reproduction.
Vaccine development: For example, the yellow fever vaccine is already mature, but vaccines for dengue, Zika, and chikungunya are still in progress.
For instance, in 2023, Singapore launched a "mosquito-free campus" program, converting open drainage ditches on campus into closed water channels and regularly placing larvicide granules, significantly reducing the incidence of dengue fever.
Similarly, in 2024, Foshan in Guangdong, China, piloted the "mosquito control with mosquitoes" approach by releasing male mosquitoes carrying Wolbachia bacteria to reduce the fertility rate of Aedes albopictus, with preliminary data showing good results.
These explorations not only reflect the progress of technology in combating nature but also warn us: the public health defense line of human society requires long-term investment, cross-field cooperation, and participation from all.