Zoonotic diseases are those illnesses that can be transmitted between animals and humans. These diseases can be caused by bacteria, viruses, fungi, parasites, or other infectious agents. Transmission of these diseases can occur through direct contact with infected animals, ingestion of contaminated food, inhalation of aerosols or respiratory droplets, or via vectors such as mosquitoes or ticks.
In addition to the serious implications for human and animal health, it is important to understand the broader impact of zoonotic diseases and other infectious diseases on global health. According to the World Health Organization (WHO), nearly 16 percent of global deaths are attributed to infectious diseases. This underscores the importance of addressing these diseases comprehensively and taking proactive measures to prevent their spread and control their impact on public health.
Some of the zoonotic diseases we encounter include:
· Dengue: Dengue is a viral disease primarily transmitted by mosquitoes of the Aedes genus, such as Aedes aegypti, also known as the tiger mosquito. This disease is endemic in tropical and subtropical areas of the world, where the mosquitoes that transmit it can be found in abundance. In more severe cases, known as severe dengue or dengue hemorrhagic fever, the disease can cause potentially fatal complications such as severe bleeding and shock. Therefore, it is crucial to seek medical attention if you experience dengue symptoms and live in an area where this disease is common.
The Southern Cone of America is currently facing one of the worst dengue epidemics in recent history, with over 4.2 million cases reported in the first three months of 2024, and unfortunately, more than 1,200 related deaths. Faced with this public health challenge, scientists and health experts are working hard to find new tools and strategies to help prevent and combat the spread of this devastating disease.
In Brazil, public researchers have devised a revolutionary technique that uses the dengue-transmitting mosquito itself, Aedes aegypti, as a "Trojan horse" to exterminate larvae and thus reduce the population of infected mosquitoes. This innovative strategy, developed by the Fiocruz Institute and led by Professor Rodrigo Gurgel from the University of Brasilia, is based on the concept of "Larvicide Dissemination Stations (LDS)."
How does this strategy work? LDSs are traps designed with a special lure for Aedes aegypti mosquitoes. These traps, resembling black cubes, contain a fabric impregnated with pyriproxyfen, a highly effective larvicide. Mosquitoes, attracted by the water and the black color of the container, come to the traps and perch on the impregnated fabric. In doing so, they become contaminated with the larvicide, which adheres to their bodies.
Here lies the brilliance of the strategy: as mosquitoes move to other areas in search of new larval breeding sites, they carry the larvicide with them. Upon contact with water in these new sites, pyriproxyfen dissolves, acting as a lethal agent for Aedes aegypti larvae but without harming other non-target organisms. Essentially, the mosquitoes themselves become carriers of the larvicide, delivering the solution to where it is most needed.
This approach represents a significant step in the fight against dengue and other mosquito-borne diseases. By leveraging the natural behavior of mosquitoes, effective reduction in the population of Aedes aegypti and thus the spread of the dengue virus can be achieved. Furthermore, this strategy is environmentally friendly and offers a promising alternative to traditional vector control methods.
· Avian Influenza: Avian influenza, also known as bird flu, is a viral disease that primarily affects birds but can be transmitted to humans and other mammals. It is highly contagious and can have serious consequences for the poultry industry and public health. Transmission occurs mainly through direct contact with contaminated secretions or feces, as well as contact with contaminated surfaces. In humans, symptoms range from mild to severe respiratory complications and even death. Although transmission from birds to humans is rare, there is a risk that the virus may mutate and become more transmissible among humans, triggering a pandemic. To prevent its spread, biosecurity measures are applied on poultry farms, vaccination campaigns are conducted in high-risk birds, and active surveillance is carried out to detect outbreaks and respond promptly. Additionally, it is crucial to educate the population about proper hygiene and promote early detection of suspected cases.
- Recently, the World Health Organization (WHO) confirmed a case of avian influenza (H5N1) in a man in Texas, United States. This individual was exposed to dairy cattle, presumably infected with the virus. The young man, who is recovering, experienced redness in the eyes, suggesting conjunctivitis, as the only symptom.
Human infections with avian influenza A viruses, including H5N1 viruses, are rare but can occur sporadically worldwide. However, this case is particularly noteworthy as it appears to be the first human infection with H5N1 acquired through contact with an infected mammal. Although human infections with other subtypes of influenza acquired through mammals have been recorded, this situation is unique.
So far, no additional cases of human infection associated with this particular event have been identified. The WHO emphasizes that this is the first time that human infection with H5N1 acquired through contact with infected livestock has been confirmed.
- The National Veterinary Services Laboratory in North Carolina has identified a new case of avian influenza in a dairy herd, marking a milestone in an outbreak that has already affected six states in the United States. This incident, which adds to a series of previous positives, raises concerns about animal health and food safety, as well as the potential for transmission to humans.
The initial cases were identified through unpasteurized clinical samples of milk from sick cattle on farms in Kansas and Texas, where dead wild birds were also found, suggesting a possible transmission route. Since then, up to twenty cases have been confirmed, with Texas being the most affected state.
Federal agencies are working closely with the industry to encourage rapid reporting of livestock diseases, thereby minimizing the impact on farmers, consumers, and other animals. Although only 10% of the livestock on affected farms show symptoms such as reduced production and loss of appetite, authorities assure that the loss of milk will not have a significant impact on supply or prices.