Although dengue was once an occasional infection that caused long-interval epidemics, today it is considered the primary mosquito-borne viral disease in the world.
According to the World Health Organization (WHO), an estimation of fifty to one hundred million cases of dengue fever are recorded yearly. Half a million of the cases result in a more severe form of dengue fever known as dengue hemorrhagic fever (DHF).
DHF affects children under 15 years of age and is detected by the sudden beginning of the fever and vascular leak syndrome.
Now, DHF is viewed globally as a severe mosquito-borne virus. It is endemic to more than 100 countries worldwide, mostly tropical and subtropical regions.
During the 1950s to most of the 1970s, the dengue epidemic was uncommon in the majority of South and Central America because the Aedes aegypti was cleared.
However, when the extermination was stopped, Aedes aegypti started to reinvade those regions. In 1997, the dengue virus increased again.
Dengue vs dengue hemorrhagic fever
Dengue is caused by Dengue virus (DENV), a mosquito-borne flavivirus. DENV causes a wide range of diseases in humans, from Dengue Fever (DF) to a life-threatening disease called Dengue Hemorrhagic Fever (DHF) or Dengue Shock Syndrome (DSS).
Dengue hemorrhagic fever (DHF) is characterised by increased vascular permeability and abnormal blood clotting mechanisms. DHF is potentially a deadly complication with symptoms similar to those of dengue fever, but after several days the patient becomes irritable, restless, and sweaty.
What is dengue?
Dengue fever, or “break bone fever,” is characterised by the intense beginning of high fever 3–14 days following the bite of an infected mosquito.
Symptoms include frontal headache, rash, and low white blood cell count. The patient may also experience anorexia and nausea.
Those symptoms usually last about a week, but weakness and anorexia may persist for several weeks.
Often, dengue infections produce no symptoms or minor symptoms, particularly in children and those with no history of having dengue infection.
The primary medical complications of dengue fever are febrile seizures and dehydration.
Treatment of dengue fever emphasises on:
- Relieving the symptoms of pain
- Controlling fever
- Advising patients to avoid nonsteroidal medications as it might increase the risk for bleeding
- Reminding patients to drink more liquids, especially when they have a high fever
- Keeping the white blood cells count in check.
What is dengue hemorrhagic fever?
Some patients with dengue fever eventually develop dengue hemorrhagic fever (DHF), a severe and sometimes deadly form of the disease.
Around the time the fever slowly subsides (usually 3–7 days after symptoms begin), the patient may develop warning signs of severe illness.
These include severe abdominal pain, relentless vomiting, a stamped change in temperature (from fever to hypothermia), bleeding or change in mental status (irritability, confusion, or dullness).
The patient may also have early signs of shock, including restlessness, cold skin, fast frail heartbeat, and narrowing of the pulse pressure.
Patients with dengue fever should return to the hospital if they develop any of the mentioned signs.
Despite the name, the criteria that differentiate DHF from dengue is not hemorrhaging, but a plasma leakage due to higher vascular permeability.
Plasma leakage is a process when the protein-rich, fluid component of the blood leaks from blood vessels into the surrounding tissue. The degree of plasma leakage varies between each patient and can lead to intravascular volume depletion and circulatory insufficiency.
What is dengue shock syndrome?
The dengue shock syndrome (DSS) is characterised by bleeding that may appear as tiny spots of blood on skin and more significant patches of blood under the skin.
The shock that the patients experience unexpectedly happens soon after the drop in temperature between the third and the seventh day of the disease.
Following are the regular signs of circulatory failure:
- The skin becomes cold, blotchy, and congested.
- Circumoral cyanosis is often noticed.
- The pulse gets fast.
Patients may initially feel lethargic, then become restless and rapidly enter a critical stage of shock.
DSS is typically characterised by a rapid weak pulse and narrow pulse pressure or hypotension with anxiety and cold, clammy skin.
Patients with dengue can quickly progress into DSS, which, if not immediately treated, can prompt severe complications and death. Patients may pass into a phase of profound shock, with the blood pressure or pulse becoming undetectable.
However, most patients remain conscious almost to the terminal stage. The span of shock is short: typically, the patient recovers rapidly or dies within 12–24 hours.
Causes of DHF
Dengue hemorrhagic fever can occur when someone gets bitten by a mosquito or exposed to blood infected with the dengue virus. Infected mosquitoes are the most common causes.
There are four different dengue virus. Once a person is infected with one of the viruses, they develop lifelong immunity to that virus.
However, this immunity will not give protection to the rest of the viruses. It is possible to be infected with dengue virus four times in a lifespan.
Recurrent exposure to the dengue virus can make it more probable to get DHF.
The signs of DHF are:
- High Fever
- Thrombocytopenia (platelet count <100,000 cell/cumm)
- Evidence of plasma leakage, as indicated by hemoconcentration.
Hemoconcentration is characterised as a 20% increase in hematocrit (RBC count) with a simultaneous decrease in WBC, is widely used as an indicator of plasma leakage.
High Risk for Dengue Hemorrhagic Fever
The risk of contracting the dengue virus is high on those living or travelling to tropical and subtropical.
Other people at higher risk include:
- Infants and small children
- Pregnant women (the virus could be passed from mother to fetus)
- Elderly adults
- Those with weak immune systems
Symptoms of DHF
One may feel like they are recovering from dengue fever and suddenly develop new and severe symptoms.
Symptoms of dengue hemorrhagic fever include:
- Acute or sudden fever
- Severe abdominal pain
- Bleeding or bruising under the skin
- Cold or clammy skin
- Large decrease in blood pressure (shock)
- Frequent vomiting with or without blood
- Black stools, like coal tar
- Excessive thirst (dry mouth)
More severe complications of hemorrhage include vaginal bleeding, gastrointestinal bleeding, and intracranial bleeding.
Treatment of DHF
The objective of treatment is to manage side effects and keep the infection from getting more severe. Extreme cases may require emergency treatments such as:
- Hydration with intravenous (IV) fluids
- Over-the-counter or prescription drugs to manage pain
- Electrolyte therapy
- Blood transfusions
- Careful monitoring of blood pressure
- Oxygen therapy
- Skilled nursing observation
All of these treatments are aimed at controlling and easing the symptoms while helping the body heal naturally. Doctors will continue to observe the body’s response. Severe dengue fever is harder to treat because the symptoms are worse and appear at a faster rate.
How can dengue hemorrhagic fever be prevented?
Dengvaxia is the only licensed vaccine for dengue and it is approved for use in those aged 9 to 45 that live in regions with a high occurrence of dengue fever. The vaccine is given in three doses with six months interval.
The vaccine is only approved for older children because younger vaccinated children appear to be at higher risk of severe dengue fever and hospitalisation two years after receiving the vaccine.
The World Health Organization mentions that the vaccine is not a useful tool on its own to reduce dengue fever in zones where the illness is common. Controlling mosquito breeding and human exposure is still the most critical part of prevention.
The best way to prevent dengue includes the following measures:
- Keep the windows and doors in the house closed. Aedes aegypti are most active from dawn to dusk, but can also bite at night.
- Wear protective clothing. When going into mosquito-infested areas, wear covered clothes.
- Use mosquito repellent. Use a repellent containing at least a 10% concentration.
- Curb mosquito breeding. Aedes aegypti typically breeds in standing water. It is suggested to lower mosquito populations by eliminating habitats where they lay their eggs. Clean containers that hold standing water.
The standpoint for dengue hemorrhagic fever relies on how early the condition is identified. People who receive care in the beginning stages of dengue infection will usually recover.
It’s important to talk to a doctor about any international travel plans and to be aware of any diseases in the travelling area.
The Centers for Disease Control and Prevention (CDC) keeps an up-to-date health map to show areas that have recent reports of dengue virus. See a doctor immediately if there are any symptoms of dengue.