Dengue: 10 more die, 990 hospitalized

 
Ten more people have died of dengue while 990 new patients have been hospitalised with the Aedes mosquito-borne disease across Bangladesh over the past 24 hours. The number of patients hospitalised with the disease this year has risen to 88,715. The total number of deaths from the illness now stands at 471.

The Directorate General of Health Services, or DGHS, said as many as 345 new patients were hospitalised in the Dhaka metropolitan area until Tuesday.

In addition, 215 were hospitalised in the Dhaka Division, 38 in the Mymensingh Division, 103 in the Chattogram Division, 146 in the Khulna Division, 59 in the Rajshahi Division, two in the Rangpur Division, 81 in the Barishal Division, and one in the Sylhet Division.

As many as 3,522 patients are currently undergoing treatment for dengue in hospitals across the country. Of them, 1,373 are hospitalised in the capital and 2,149 are outside Dhaka.

The DGHS has been keeping records of dengue hospitalisations and fatalities since 2000.

Since then, a record 321,179 dengue hospitalisations were logged in 2023. That year also saw the most deaths with 1,705.

Dengue (break-bone fever) is a viral infection that spreads from mosquitoes to people. It is more common in tropical and subtropical climates.

Most people who get dengue will not have symptoms. But for those who do, the most common symptoms are high fever, headache, body aches, nausea, and rash. Most will get better in 1-2 weeks. Some people develop severe dengue and need care in a hospital.

In severe cases, dengue can be fatal. 

You can lower your risk of dengue by avoiding mosquito bites especially during the day.

Dengue is treated with pain medicine as there is no specific treatment currently.

DIAGNOSTICS AND TREATMENT:

There is no specific treatment for dengue. The focus is on treating pain symptoms. Most cases of dengue fever can be treated at home with pain medicine.

Acetaminophen (paracetamol) is often used to control pain. Non-steroidal anti-inflammatory drugs like ibuprofen and aspirin are avoided as they can increase the risk of bleeding.

For people with severe dengue, hospitalization is often needed.

GLOBAL BURDEN:

The incidence of dengue has grown dramatically around the world in recent decades, with cases reported to WHO increasing from 505 430 cases in 2000 to 5.2 million in 2019. A vast majority of cases are asymptomatic or mild and self-managed, and hence the actual numbers of dengue cases are under-reported. Many cases are also misdiagnosed as other febrile illnesses (1).

The highest number of dengue cases was recorded in 2023, affecting over 80 countries in all regions of WHO. Since the beginning of 2023 ongoing transmission, combined with an unexpected spike in dengue cases, resulted in a historic high of over 6.5 million cases and more than 7300 dengue-related deaths reported.

Several factors are associated with the increasing risk of spread of the dengue epidemic: the changing distribution of the vectors (chiefly Aedes aegypti and Aedes albopictus mosquitoes), especially in previously dengue naïve countries; the consequences of El Niño phenomena in 2023 and climate change leading to increasing temperatures and high rainfall and humidity; fragile health systems in the midst of the COVID-19 pandemic; and political and financial instabilities in countries facing complex humanitarian crises and high population movements.

One modelling estimate indicates 390 million dengue virus infections per year of which 96 million manifest clinically (2). Another study on the prevalence of dengue estimates that 3.9 billion people are at risk of infection with dengue viruses (3).

The disease is now endemic in more than 100 countries in the WHO Regions of Africa, the Americas, the Eastern Mediterranean, South-East Asia and the Western Pacific. The Americas, South-East Asia and Western Pacific regions are the most seriously affected, with Asia representing around 70% of the global disease burden.

Dengue is spreading to new areas in Europe, the Eastern Mediterranean and South America.

The largest number of dengue cases reported was in 2023. The WHO Region of the Americas reported 4.5 million cases, with 2300 deaths. A high number of cases were reported in Asia: Bangladesh (321 000), Malaysia (111 400), Thailand (150 000), and Viet Nam (369 000).

TRANSMISSION:

The dengue virus is transmitted to humans through the bites of infected female mosquitoes, primarily the Aedes aegypti mosquito. Other species within the Aedes genus can also act as vectors, but their contribution is normally secondary to Aedes aegypti. However, in 2023, a surge in local transmission of dengue by Aedes albopictus (tiger mosquito) has been seen in Europe.

After feeding on a infected person, the virus replicates in the mosquito midgut before disseminating to secondary tissues, including the salivary glands. The time it takes from ingesting the virus to actual transmission to a new host is termed the extrinsic incubation period (EIP). The EIP takes about 8-12 days when the ambient temperature is between 25-28°C. Variations in the extrinsic incubation period are not only influenced by ambient temperature; several factors such as the magnitude of daily temperature fluctuations, virus genotype, and initial viral concentration can also alter the time it takes for a mosquito to transmit the virus. Once infectious, the mosquito can transmit the virus for the rest of its life.

HUMAN-TO-MOSQUITO TRANSMISSION:

Mosquitoes can become infected by people who are viremic with the dengue virus. This can be someone who has a symptomatic dengue infection, someone who is yet to have a symptomatic infection (they are pre-symptomatic), and also someone who shows no signs of illness (they are asymptomatic).

Human-to-mosquito transmission can occur up to 2 days before someone shows symptoms of the illness, and up to 2 days after the fever has resolved.
The risk of mosquito infection is positively associated with high viremia and high fever in the patient; conversely, high levels of DENV-specific antibodies are associated with a decreased risk of mosquito infection. Most people are viremic for about 4-5 days, but viremia can last as long as 12 days.

MATERNAL TRANSMISSION:

The primary mode of transmission of the dengue virus between humans involves mosquito vectors. There is evidence however, of the possibility of maternal transmission (from a pregnant mother to her baby). At the same time, vertical transmission rates appear low, with the risk of vertical transmission seemingly linked to the timing of the dengue infection during the pregnancy. When a mother does have a dengue infection when she is pregnant, babies may suffer from pre-term birth, low birthweight, and fetal distress.

OTHER TRANSMISSION MODES:

Rare cases of transmission via blood products, organ donation and transfusions have been recorded. Similarly, transovarial transmission of the virus within mosquitoes have also been recorded.