Symptoms, transmission, and current treatments for dengue

Dengue

Symptoms, transmission, and current treatments for dengue

What is dengue?

Dengue is caused by a virus that is mostly transmitted by the bite of female mosquitoes of the species Aedes aegypti. Dengue symptoms range from none to serious flu-like symptoms. A small proportion of people develop severe dengue, which can be fatal.

There are four closely related dengue viruses, which are called dengue serotypes. Although recovery from infection gives immunity from the same dengue serotype, it also increases the risk of severe dengue if people are later infected by a different serotype.

Dengue is the most widely distributed mosquito-borne viral disease in the world. It continues to spread rapidly because of climate change, rapid urbanization, and population growth. Outbreaks are usually seasonal, peaking during and after rainy seasons. The World Health Organization classifies dengue as one of the top ten threats to public health.

What is the impact of dengue?

3.9 billion people at risk of dengue infection
Endemic in 129 countries, with 70% of cases in Asia
About 390 million infections per year, 96 million with symptoms
85% increase in number of cases from 1990 to 2019
60% of the world’s population predicted to be at risk by 2080
Puts immense pressure on health systems: it costs three times more to manage dengue than cholera
Most dengue cases are underreported with many cases asymptomatic, mild and self-managed, or misdiagnosed

Source: European Centre for Disease Prevention and Control

What are current treatments for dengue?

There are no specific antiviral drugs to treat dengue infection.

Acetaminophen or paracetamol can be taken to control muscle aches, pains, and fever. Non-steroidal anti-inflammatory drugs such as ibuprofen and aspirin should be avoided.

Hospitalised dengue patients must be closely observed and their fluid intake carefully managed, according to strict guidelines. In countries where early detection and such medical care is available, the fatality rate from dengue has dropped to below 1%.

The currently available vaccine is limited to people aged 9-45 years old who have had at least one previous episode of dengue virus infection. Several additional dengue vaccine candidates are under evaluation.

The lack of treatment options increases the risk of people developing severe dengue, which is potentially fatal.

What new treatments for dengue are needed?

Dengue-specific treatments are needed to treat the disease at different stages and to reduce the risk of an infection progressing to severe disease.

What dengue treatments are we working on?

We are establishing a global partnership with dengue-endemic countries to carry out pre-clinical studies and clinical trials to find a safe, affordable, and effective treatment for dengue. We are looking at repurposed drugs or drug combinations as well as pursuing a portfolio of dengue treatment options already in clinical development.

Find out about our work developing treatments for dengue.

How do you get dengue?

Insect bites: the virus that causes dengue can be transmitted by the bite of infected female mosquitoes of the species Aedes aegypti and, to a lesser extent, the species Aedes albopictus
Mother-to-child: possible transmission from mother to child during pregnancy or childbirth
Rare cases of transmission via blood products, organ donation, and transfusions

What are the symptoms of dengue?

Dengue
Dengue can have no symptoms or cause only mild illness, but it can also cause flu-like symptoms such as:

high fever (40°C/104°F)
severe headache
pain behind the eyes
nausea
vomiting
swollen glands
rash
muscle, joint, or bone pains so severe that dengue is sometimes referred to as ‘breakbone fever’

Severe dengue
Severe dengue happens when blood vessels become damaged and leaky, and the number of platelets (cells which form clots) drops. As a result, severe dengue can cause shock, internal bleeding, bleeding gums or nose, organ failure, and death. The symptoms of severe dengue include:

severe abdominal pain
persistent vomiting
rapid breathing
bleeding gums or nose
fatigue
restlessness
liver enlargement
blood in vomit or stool
potentially fatal

How is dengue diagnosed?

Dengue infection can be diagnosed in several ways, all of which require a blood sample. Reverse transcriptase–polymerase chain reaction (RT–PCR) detects the virus directly and is the gold standard; it can be used in the first days after infection. Rapid diagnostic tests are also available, which test for a protein produced by the virus called NS1. Serological methods can be used to confirm recent (within the previous 3 months) or past infection.