In recent years, the dengue It has become an increasingly serious public health problem. Until 1970 outbreaks of this disease had been reported in only 9 countries in the world, while last year it occurred in more than 100according to data from the World Health Organization (OMS).
One of those countries is Argentinawhich in the previous 2023/2024 dengue season, recorded the historic number of infections, with more than 783,000 and deaths (503).
The person responsible for this happening is almost entirely the Aedes aegypti mosquito, an insect that is characterized by being small, just 3 to 4 millimeters, dark brown in color, with black and white striped legs.
Today, the Aedes aegypti it’s a domestic and domiciliary mosquito, adapted to the urban environment, due to its ease in laying eggs in buckets of water, flower pots, puddles, abandoned tiresclogged ducts or any other small container with that stagnant liquid. Males have feathery antennae, but are not hematophagous (do not feed on blood), and do not play an active role in disease transmission.
On the other hand, the female mosquito becomes infected with dengue after feeding on the blood of a person who has the virus in their body (whether or not they may have symptoms of the disease) and thus, after a few days, she can transmit the virus to others. people when it bites them.
“When the mosquito bites a infected personthis replicates in the midgut of the mosquito before disseminating to secondary tissues, such as the salivary glands. The time between ingestion of the virus and transmission to a new host is called extrinsic incubation periodand when the ambient temperature ranges between 25 °C and 28 °C it lasts between 8 and 12 days. Once it has become infective, the mosquito can transmit the pathogen for all his life”explain WHO experts.
Meanwhile, the United States Centers for Disease Control and Prevention (CDC) commented that “when a mosquito bites, it pierces the skin with a specific part of the mouth (the proboscis) to suck blood. As it feeds, the mosquito inject saliva into the skin. Your body reacts to the saliva and a itchy lump. Some people only have a mild reaction to the bites. Other people have a stronger reaction, and may have a large area that is swollen, painful, and red.”
After the bite of the Aedes aegyptithe reaction of each individual’s body is to generate discomfort that may be greater or lesser, while It does not differ significantly from the injuries caused by other species of mosquitoes that do not transmit the dengue virus..
After a few days, it is key to pay attention to the symptoms and consult a doctor if you suffer from high fever and pain in the joints, head and behind the eyes.
Originally from Africadengue was introduced to the American continent through the Aedes aegypti mosquito during the time of Spanish and Portuguese colonization through maritime trade in the 17th and 18th centuries.
This insect, known for its role as a transmitter of diseases such as dengue, zika, chikungunya and yellow fever did not always live in the Americas. According to recent research led by Dr. Sylvia Fischer, researcher at the National Council of Scientific and Technical Research (CONICET) of Argentina, this mosquito has its origin in sub-Saharan Africa. There, he lived in the hollows of trees and fed on the blood of non-human animals, a very different lifestyle from the one he adopted after his arrival on the American continent.
The discovery, which yields new light on mosquito historyshows how this insect survived a long and challenging intercontinental journey, successfully adapting to a new environment. “The water barrels on ships of the time became ideal larval habitats for this mosquito, facilitating its migration and adaptation to a new continent,” explained Fischer, who also directs the Mosquito Study Group at the Faculty of Exact and Natural Sciences of the University of Buenos Aires (UBA).
The scientific article published in 2013 in the magazine Memories of the Oswaldo Cruz Institute highlights that the Aedes aegypti it may have arrived in America shortly after the arrival of European colonizers. This process coincided with the time when the Portuguese and Spanish ships sailed between Africa, Europe and America transporting enslaved people and goods. During these long voyages, which often lasted weeks, the ships had to transport large quantities of food and water.
The barrels used to store water became an unexpected vehicle for mosquito larvae. This artificial habitat allowed Aedes aegypti gradually adapt to the human environmentmarking a crucial change in their way of life. Originally, the insect depended on holes in trees to lay its eggs, but over time it managed to establish itself in the domestic environment, where humans became its main source of food.
The impact of this accidental migration was significant. Before the 15th century, yellow fever, transmitted by Aedes aegypti, was known in Africa, but not in America. However, After the arrival of the mosquito to the continent, the first recorded outbreak occurred in Yucatán in 1648, according to the aforementioned document.. Cases may have occurred in Haiti since 1495, although there are no confirmed records of this.
This event marked the beginning of a dangerous relationship between the mosquito and the American population. Since then, Aedes aegypti has established itself as a key disease vector that continue to affect millions of people in the region.
The history of the Aedes aegypti is also an example of its remarkable capacity for adaptation. In Africa, this mosquito coexisted with non-human animals and depended on natural ecosystems to complete its life cycle. However, Upon arriving in America, he had to adjust to an urban environment. This transition included a change in their feeding behavior, going from preferring animal blood to focusing almost exclusively on humans.
In American cities, the mosquito found ideal conditions to reproduce: stagnant water in domestic containers, favorable temperatures, and a human population that offered a constant supply of blood. Their ability to adapt to these changes has been key to their success as an invasive species and disease vector.
Currently, Aedes aegypti is widely distributed in the Americas, where it continues to be a public health challenge. The diseases it transmits, such as dengue, affect millions of people every year in Latin America and other parts of the world. According to WHO data, lOutbreaks of these diseases are on the risedriven in part by climate change and urban expansion that favor the proliferation of the mosquito.
Fischer emphasizes that, although it is perceived today as a local species, Aedes aegypti is actually an intruder that arrived on the continent at a critical time in history. “In summary, the mosquito that is currently putting the Latin American population on alert is not local, but rather arrived to the continent through intercontinental transport,” says the specialist.
Knowledge of the history of this mosquito not only offers insight into its expansion, but also helps understand the challenges posed by its control. The eradication of Aedes aegypti has been a difficult goal to achieve due to its ability to quickly adapt to new conditions.. This underlines the importance of prevention strategies, such as eliminating breeding sites and promoting vaccination campaigns against diseases such as dengue and yellow fever.
The case of Aedes aegypti also illustrates how Interactions between humans and their environment can have unexpected and long-lasting consequences. What began as an accidental trip in water barrels centuries ago has evolved into a major public health concern in the Americas.
The historic migration of Aedes aegypti from Africa to the Americas highlights global interconnectedness even in times past and underscores the importance of understanding the impact of invasive species. This knowledge allows scientists and health authorities to develop better strategies to control the mosquito and mitigate outbreaks of diseases it transmits.
Ultimately, the study led by Sylvia Fischer and the historical analysis of the mosquito offer an opportunity to reflect on the role of science in protecting public health. By understanding how this insect adapted and thrived on a foreign continent, paths are opened to more effectively face the challenges it represents in the 21st century.
