Dengue cases surge in Asia

Amidst the bizarre of COVID-19 spread, the dengue outbreak in several countries has put the people in an even more difficult state. The fear of getting tested positive for the coronavirus have stopped thousands of people from seeking medical attention for dengue. Further, the misdiagnosis of dengue as COVID-19 and vice versa has created more complications. Even though dengue has been an annually occurring threat, the pandemic has made it severe this year.
Dengue is the fastest spreading mosquito-borne viral disease and is one of the World Health Organizations top 10 threats to global health in 2019. Dengue is pandemic prone, and outbreaks are observed in tropical and sub-tropical areas and have recently caused outbreaks in parts of the continental United States and Europe. A study on the prevalence of dengue estimates that 3.9 billion people are at risk of infection with dengue viruses. Despite the risk of infection existing in 129 countries, 70% of the actual burden is in Asia.

All travellers are at risk during outbreaks. Long-term travellers and humanitarian workers going to areas where Dengue is endemic are at higher risk. Whereas Dengue prominently occurs in urban and suburban settings with higher transmission rates during the rainy season.
In Asia so far in June/July 2020, the prevalence of dengue in some of the countries at risk are as follows.
Indonesia 68 700 cases and 446 deaths.
Malaysia 59 378 cases and 96 deaths.
Philippines 50 169 cases and 173 deaths
Vietnam 31 466 cases and 3 deaths.
Sri Lanka 23 217 cases and 0 deaths.
Thailand & Singapore over 17,000 cases.

Experts say that the countries in the region that are above the equator are“going into a critical time” as they enter the rainy season, usually between July and November. That period coincides with increased transmission for dengue fever. Further, they highlight that the lockdown measures may also be contributing to increased mosquito larvae in areas such as unmanned construction sites, where pools of stagnant water form due to rains, creating the perfect breeding site for these mosquitoes.

Dengue and the symptoms
Dengue is a viral infection caused by four types of viruses (DENV-1, DENV-2, DENV-3, DENV-4) belonging to the Flaviviridae family. The viruses are transmitted through the bite of infected Aedes aegypti and Aedes albopictus female mosquitoes that feed both indoors and outdoors during the daytime (from dawn to dusk). These mosquitoes thrive in areas with standing water, including puddles, water tanks, containers and old tires. Lack of reliable sanitation and regular garbage collection in the environment contributes to the spread of these mosquitoes.
When considering the symptoms of dengue infection, in some cases it is asymptomatic which means the infected person does not exhibit any symptoms. For those with symptoms, they get ill between 4 to 7 days after the bite. The infection is characterized by flu-like symptoms which include a sudden high fever coming in separate waves, pain behind the eyes, muscle, joint, and bone pain, severe headache, and a skin rash with red spots.

At times the illness may progress to Dengue Hemorrhagic Fever (DHF) which exhibit symptoms like severe abdominal pain, vomiting, diarrhoea, convulsions, bruising, and uncontrolled bleeding. High fever can last from 2 to 7 days. Complications can lead to circulatory system failure and shock, and can be fatal (also known as Dengue Shock Syndrome). Dengue is related to Zika Virus, Yellow Fever, West Nile Virus, and Japanese Encephalitis. There is also a possibility that it can be misdiagnosed for Chikungunya, Zika Virus, or Yellow Fever.
Dengue symptoms are almost indistinguishable from COVID-19. Whereas both present symptoms like fever, breathing difficulties, headaches, fatigues and a loss of appetite. Complicating things further, it’s been reported that COVID-19 patients can get false-positive results from rapid serological testing for dengue. And experts emphasize that “Very early on, there was misdiagnosis because there was not as much COVID but there was dengue. So they misdiagnosed dengue. But now it could be the other way round, they may be misdiagnosing dengue patients as COVID.”

When considering about the prevention and control the World Health Organization warns “if you know you have dengue, avoid getting further mosquito bites during the first week of illness. The Virus may be circulating in the blood during this time, and therefore you may transmit the virus to new uninfected mosquitoes, who may, in turn, infect other people”.
The proximity of mosquito vector breeding sites to human habitation is a significant risk factor for dengue as well as for other diseases that Aedes mosquito transmit. At present, the main method to control or prevent the transmission of the dengue virus is to combat the mosquito vectors. This is achieved through Prevention of mosquito breeding, Personal protection from mosquito bites, Community engagement, Reactive vector control and Active mosquito and virus surveillance.

In case of Vaccines against dengue, the first dengue vaccine, Dengvaxia (CYD-TDV) which was developed by Sanofi Pasteur was licensed in December 2015 and has now been approved by regulatory authorities in approximately 20 countries. The use of the vaccine is targeted for persons living in endemic areas, ranging from 9-45 years of age, who have had at least one documented dengue virus infection previously.

By Jumana J.

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