BACKGROUND OF DENGUE INFECTION
Dengue is one of the most widespread and important viral infections transmitted by mosquitoes, affecting millions worldwide. As of 2015, approximately 3.2 million people globally were infected, with 2.5-3 billion individuals living in 112 countries where dengue is common. The virus that causes dengue belongs to the ‘Flavivirus’ family and has four distinct serotypes (types of the virus). An infection by one serotype gives lifelong immunity against that particular type, but only temporary protection (about two years) against the others. This means a person can get infected by different serotypes throughout their life.
Dengue is spread by mosquitoes from the ‘Aedes’ genus, which are found mostly in tropical and subtropical areas. These mosquitoes become infectious 5-10 days after biting an infected person, and they remain capable of spreading the virus for the rest of their lifespan, which can be up to a month. The ‘Aedes albopictus’ mosquito can survive in cooler climates, making it a potential risk in more temperate regions.
The global spread of dengue has increased significantly, with 40-50% of the world’s population now at risk of infection. Severe cases of dengue, which primarily affect Asian and Latin American countries, are a leading cause of hospitalization and death. The World Health Organization (WHO) has even ranked dengue as one of the top ten global health threats in 2019.
A dengue infection can range from being completely asymptomatic to causing classic dengue fever (DF), a condition characterized by a sudden onset of high fever, intense headache, pain behind the eyes, body pain (including muscles and bones), weakness, vomiting, and sometimes a rash. The extreme body pain led to the nickname “breakbone fever.”
A small percentage of those who contract dengue develop a more severe form of the disease, known as severe dengue, which can lead to serious complications like bleeding, blood vessel leakage, and organ damage. This can result in a life-threatening condition known as dengue shock syndrome, especially when there is circulatory collapse due to severe blood loss.
There are two patterns of dengue transmission: ‘epidemic’ and ‘hyperendemic’. Epidemic transmission occurs when a dengue virus is introduced to a new area, leading to sudden outbreaks. Hyperendemic transmission is when multiple serotypes of the virus circulate continuously in a region, causing a higher risk of severe dengue and making travelers to such areas more likely to contract the disease.
Diagnosing dengue can be challenging due to its nonspecific symptoms, which resemble other febrile illnesses. Lab tests like serology, RT-PCR, and virus cultures are crucial to confirm the infection. While dengue typically resolves on its own with proper rest and hydration, severe cases require close medical monitoring and intensive care.
Historically, records of dengue-like illnesses date back centuries, with the first epidemic described in the 1630s in the West Indies. Since World War II, the spread of dengue has intensified, with outbreaks becoming more frequent and severe, particularly in Asia, Latin America, and parts of the Pacific. Countries that had previously eradicated the ‘Aedes’ mosquitoes have seen a resurgence in dengue cases due to halted mosquito control efforts.
Dengue remains a major global health challenge today, and its spread is driven by factors like climate change, urbanization, and travel. Continued efforts in vector control and disease management are critical to reducing its impact worldwide.
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