O Dia em que o Vírus da DENGUE se tornou uma AMEAÇA GLOBAL

Summary

This video explores the persistent issue of dengue in Brazil, highlighting the role of four different virus serotypes and the Aedes mosquitoes as key contributors to yearly epidemics. The script delves into how the dengue virus adapted over centuries, making it challenging to control, and explains how the virus spreads silently between epidemics. It also covers factors like global warming, resistance to insecticides, and poor prevention efforts that exacerbate the problem. With a call to action for better prevention and public health measures, the video emphasizes the need for vigilance in controlling this ongoing threat.

Takeaways

• 😀 Dengue is caused by four different virus serotypes (Dengue 1, 2, 3, and 4), making it possible for a person to get infected up to four times during their life.
• 😀 The immune system's response to one serotype does not protect against others, and subsequent infections with different serotypes can lead to more severe forms of the disease.
• 😀 Secondary Dengue infections can trigger severe symptoms like hemorrhagic fever due to a process called antibody-dependent enhancement, where antibodies from a previous infection worsen the situation.
• 😀 The Aedes mosquito, specifically Aedes aegypti and Aedes albopictus, is the primary vector of the Dengue virus, thriving in stagnant water.
• 😀 These mosquitoes first arrived in the Americas during the era of large-scale navigation and the slave trade, hitching rides on ships.
• 😀 Mosquitoes can transmit the Dengue virus through their eggs, meaning offspring mosquitoes can already be infected at birth if the mother was infected.
• 😀 Mosquitoes have developed resistance to insecticides over time, making it increasingly difficult to control their population.
• 😀 Rising global temperatures are expanding the regions where Aedes mosquitoes can survive, increasing the potential spread of Dengue to new areas like Florida and Europe.
• 😀 The relationship between the virus and the mosquito is highly adaptive, with the virus evolving alongside the mosquito to maximize transmission opportunities.
• 😀 Dengue often goes unnoticed, as over 70% of infections are asymptomatic, allowing the virus to circulate silently, leading to unexpected epidemics when conditions align.
• 😀 The lack of consistent prevention efforts, especially during periods of lower mosquito population and fewer cases, contributes to recurring outbreaks, highlighting the need for continuous control measures.

Q & A

Why does Dengue continue to be a recurring problem in Brazil?

Dengue continues to be a recurring problem in Brazil due to the existence of four different serotypes of the virus, which allows for multiple infections throughout a person's life. Additionally, the virus's ability to evade immunity from previous infections and the presence of efficient mosquito vectors like Aedes aegypti and Aedes albopictus contribute to ongoing epidemics.

What are the four serotypes of Dengue, and how do they differ?

The four serotypes of Dengue are Dengue 1, Dengue 2, Dengue 3, and Dengue 4. These serotypes are distinct enough to trigger different immune responses but are not different enough to be considered separate species. The presence of these serotypes allows for repeated infections, with varying degrees of severity depending on which serotype infects the individual.

How does a second infection with a different serotype of Dengue affect the body?

When a person is infected with a second Dengue serotype, the antibodies from the first infection do not effectively neutralize the new virus. Instead, these antibodies can enhance the infection, allowing the virus to infect immune cells called monocytes, leading to increased viral replication, inflammation, and potentially severe forms of the disease, such as Dengue hemorrhagic fever.

How does the Aedes mosquito contribute to the spread of Dengue?

The Aedes mosquito, particularly Aedes aegypti and Aedes albopictus, is the main vector for transmitting the Dengue virus. The mosquito lays its eggs in water, and the virus is passed on when the mosquito bites an infected person. The mosquito is highly adapted to urban environments, allowing it to spread the virus effectively, especially in areas with poor control measures.

Why are there more cases of Dengue in regions that were previously not affected?

Dengue is spreading to new regions due to factors like climate change, which increases the areas where Aedes mosquitoes can survive. Furthermore, the mosquitoes' increasing resistance to insecticides and more global travel has allowed the virus to reach places like the United States, Europe, and parts of South America, where it was once rare.

How did the Aedes mosquito end up in the Americas?

The Aedes mosquito was brought to the Americas by ships during the Age of Exploration, around the 1500s. The mosquito's eggs likely traveled in the holds of ships from Africa and Asia, where they hatched and established new populations. This brought both the mosquito and the Dengue virus to new continents.

What is 'cryptic transmission' of Dengue, and how does it contribute to epidemics?

Cryptic transmission refers to the silent circulation of the Dengue virus in a population without noticeable outbreaks. Many people infected with Dengue do not show symptoms, allowing the virus to spread unnoticed. This can set the stage for a major epidemic when conditions change, such as an increase in mosquito populations or a decrease in immunity among the population.

Why did the Dengue virus seem to disappear for a while and then return in full force?

The virus may appear to disappear during periods of low mosquito populations and reduced disease transmission. However, the virus can continue circulating silently within the population (cryptic transmission) until conditions are right for an outbreak, such as a rise in mosquito populations, lack of proper mosquito control, and lower immunity to the virus.

How does the behavior of Aedes mosquitoes change when infected with the Dengue virus?

Research has shown that infected Aedes mosquitoes become more active and more sensitive to certain smells, which may increase their likelihood of biting a new host and spreading the virus. This altered behavior helps the virus propagate more effectively.

What is the current status of a Dengue vaccine, and why is it delayed?

A Dengue vaccine is currently being developed in phase 3 trials by the Butantan Institute in Brazil. However, the complexity of the virus, with its four distinct serotypes, has slowed down the vaccine's approval. The challenge is ensuring that the vaccine provides protection against all four serotypes and can be safely administered to the population.