What is Dengue Fever (Dengue)?
Dengue is a virus spread by mosquitoes and is a leading global health issue. Often referred to as breakbone or 7-day fever, it’s known for causing severe muscle spasms, joint pain, and high fever. It’s a representation of how severe and long-lasting the symptoms can be. Even though many people with dengue fever do not show symptoms, it can also lead to serious illness and even death. The virus is spread by Aedes mosquitoes, especially the female Aedes aegypti and Aedes albopictus, which thrive in warm, tropical regions.
The number of people affected by dengue fever has grown rapidly in the past years. It is now common in certain regions, possibly because people travel more. Over 100 million people get infected yearly, and between 20,000 to 25,000 people die from it, resulting in outbreaks worldwide. Some people who have had a type of dengue fever, known as dengue hemorrhagic fever (DHF), may develop serious conditions like excessive bleeding. Dengue fever’s symptoms often resemble those of other viral illnesses, but some unique characteristics will be discussed in the following sections.
What Causes Dengue Fever (Dengue)?
Dengue fever is caused by one of four different types of single-stranded RNA viruses, called serotypes (named DENV-1 to DENV-4). These types of viruses belong to the Flavivirus family. If you get infected by one type, your body develops lifelong immunity to that specific one. However, this doesn’t protect you against the other three types.
Risk Factors and Frequency for Dengue Fever (Dengue)
Dengue fever is a disease spread by mosquitoes that affects over 100 million people every year globally, causing 20 to 25,000 deaths, mainly among children. The disease is widespread in over 100 countries and outbreaks happen annually in the Americas, Asia, Africa, and Australia.
The disease spreads through two primary cycles:
- Mosquitoes carrying the virus from one nonhuman primate to another.
- Mosquitoes transmitting the virus from one human to another.
The cycle between human and mosquito mostly happens in urban areas. Whether the virus spreads from an infected human to a mosquito is largely dependent on the viral amount in the mosquito’s blood meal. The primary carriers of this disease are female mosquitoes, particularly of the species Aedes aegypti and Aedes albopictus.
Even though Aedes aegypti mosquitoes are linked to most infections, Aedes albopictus mosquitoes are quickly expanding their range. The latter are more resistant to cold, are aggressive feeders, albeit less frequent, which may lead to their increasing population. They tend to be active during the day and normally live indoors. Dengue fever can also spread through childbirth, blood transfusions, breastfeeding, and organ transplants.
The average age of patients was 27.2 between 1990 and 2010, which has increased to 34 since 2010. The type of dengue virus causing outbreaks varies over time. There are generally two patterns of the dengue virus transmission: epidemic dengue and hyperendemic dengue.
Epidemic dengue is when one strain of the dengue virus is at the root of introduction and transmission. This was more frequent prior to World War II. During such epidemics, all age groups are exposed, but the number of severe cases, referred to as DHF, is quite low. Hyperendemic dengue, on the other hand, is when different strains of the virus circulate within a community leading to periodic outbreaks. In such areas, children are more affected than adults and the number of DHF cases is relatively higher.
Signs and Symptoms of Dengue Fever (Dengue)
Dengue fever is a disease that generally occurs in three stages: the febrile phase, the critical phase, and the recovery phase.
The febrile phase is the first stage in dengue fever. During this time, people usually have a sudden high fever, reaching about 104 degrees Fahrenheit (or 40 degrees Celsius), that lasts for 2 to 7 days. In about 6% of cases, particularly in severe dengue fever, the fever may come and go. Accompanying symptoms can include facial flushing, skin rash, muscle and joint pain, headache, sore throat, reddening of the eyes, loss of appetite, nausea, and vomiting.
The critical phase marks the stage in the disease when the fever starts to drop, usually between the 3rd and 7th day. During this period, capillaries (small blood vessels) become more permeable and the platelet count in the blood can drop rapidly. This phase can be dangerous and, if untreated, can lead to shock, organ dysfunction, abnormal blood clotting, or bleeding.
The recovery phase comes afterwards and is characterized by the slow absorption of fluid that had leaked into tissues. During this stage, patients often have a slow heartbeat.
Expanded dengue virus syndrome refers to unusual and severe cases of dengue fever, presenting complications like seizures, inflammation of the brain or the protective lining around it, internal bleeding, liver issues, pancreatitis (inflammation of the pancreas), heart problems, respiratory distress, kidney failure, or a condition leading to the destruction of red blood cells.
Testing for Dengue Fever (Dengue)
The dengue fever is often identified by low platelet counts, low white blood cell counts, and high levels of a liver enzyme called aspartate aminotransferase. There are three levels of dengue diagnosis: probable dengue, dengue with warning signs, and severe dengue.
1. Probable dengue: This is considered if the patient lives in or has traveled to an area where dengue is common. Symptoms can include a high temperature and two or more of the following: nausea, vomiting, a skin rash, muscle pain, joint pain, a positive tourniquet test (a test that indicates the presence of small blood clots in the blood vessels), or a low white blood count.
2. Dengue with warning signs: These signs include stomach pain, continuous vomiting, abnormal fluid build-up in places like the abdomen or chest, bleeding from the nose or gums, feeling sleepy or lethargic, an enlarged liver (more than 2 cm), an increase in the proportion of red blood cells due to dehydration, and a low platelet count.
3. Severe dengue: This condition is marked by dengue fever along with severe plasma leakage (which can lead to shock), bleeding, altered consciousness, heart abnormalities, lung problems, and other organ issues, including high levels of liver enzymes.
Moreover, dengue shock syndrome is a severe condition where the patient experiences rapidly rising red blood cell count, intense stomach pain, continuous vomiting, and a dramatic decrease in blood pressure.
Doctors can detect the dengue virus through tests like an enzyme-linked immunosorbent assay (ELISA), polymerase chain reaction (PCR), or by isolating the virus from body fluids. An increase in immune system proteins or antibodies may also be seen in blood test results. The diagnosis can be confirmed through these tests, or by detecting the virus or its antigens (proteins that trigger an immune response). It is particularly important to consider dengue in pregnant patients, as the symptoms can be quite similar to the condition known as preeclampsia.
Treatment Options for Dengue Fever (Dengue)
Treatment for dengue fever varies depending on the stage of the illness. Patients without serious symptoms can often have their treatment at home. This involves taking acetaminophen (a common pain reliever) and drinking lots of fluids. It’s equally important to educate these patients about potential serious symptoms and to inform them that they should get immediate medical care if they notice any signs.
Those with serious symptoms, showing signs of severe dengue fever, or having certain risk factors such as old age, pregnancy, diabetes, or living alone, should be considered for hospital care. If any of these symptoms are present, starting intravenous (IV) hydration with fluids (known as crystalloids) can be beneficial. These fluids can be adjusted based on how the patient responds to treatment. Furthermore, if the patient is in shock due to severe dehydration and doesn’t respond well to initial IV fluids, a different type of IV fluids called colloids may be required.
Sometimes, if the patient’s condition remains unstable despite receiving adequate IV fluids or if there’s a noticeable drop in the blood concentration (hematocrit), a blood transfusion might be necessary. If the patient shows a high risk of bleeding and the platelet count drops below 20,000 cells per microliter, a platelet transfusion might be needed. It’s important that patients avoid aspirin, some types of painkillers called nonsteroidal anti-inflammatory drugs (NSAIDs), and other medications that thin the blood. There are no specific antiviral medications recommended for dengue fever and no lab tests can reliably forecast if the disease will get more severe.
What else can Dengue Fever (Dengue) be?
Diagnosing dengue fever can be tricky because its early symptoms are similar to those of many other diseases. Doctors also consider other possible causes, like measles, the flu, or diseases spread by mosquitoes, such as Zika, West Nile, Chikungunya, Malaria, and Yellow fever.
A patient’s history of vaccinations, travel, and exposure to certain situations is very important when diagnosing dengue fever. Quick lab tests can identify the dengue virus by detecting a specific part of the virus (the NS1 antigen) and using blood tests (serological tests). However, these blood tests are only useful after a few days of infection and may show wrong results if you have other similar infections like yellow fever or Zika virus.
What to expect with Dengue Fever (Dengue)
If severe dengue fever doesn’t get treated, its death rate can be as high as 10% to 20%. But when the right supportive care is given, this rate can be significantly lowered to around 1%.
Possible Complications When Diagnosed with Dengue Fever (Dengue)
There can be various complications associated with dengue fever. These can range from harm to different organs, pneumonia, seizure, and even brain infections. The following list outlines these potential complications:
- Liver injury
- Heart muscle disease (cardiomyopathy)
- Lung infection (pneumonia)
- Inflammation of the testes (orchitis)
- Inflammation of the ovaries (oophoritis)
- Seizures
- Brain disease (encephalopathy)
- Brain inflammation (encephalitis)
Recovery from Dengue Fever (Dengue)
Encouraging patients to take in a lot of fluids is essential. If a patient starts to feel hungry again, it’s often a positive indication that the infection is starting to go away.
Preventing Dengue Fever (Dengue)
The only way to dodge the dengue virus is by avoiding mosquito bites and staying clear of areas where it’s widespread.
How to Stay Safe
* Use bed nets during the day and beyond.
* Use materials treated with bug-killing chemicals like window curtains.
* Apply creams that repel mosquitoes. Look for ones that contain DEET, IR3535, or Icaridin.
* Use coils that repel mosquitoes.
* Aim to dress in long-sleeved shirts and pants.
Ways to Control It Naturally
* Fish: Introduce species like Poecilia reticulata into big water tanks or open freshwater wells. Use native fish species that eat mosquito larvae.
* Crustaceans: Use small freshwater critters as predators, especially in certain environments.
* Bacteria: Use mosquitoes infected with Wolbachia, a type of bacteria. These mosquitoes are less likely to get infected with the dengue virus compared to regular mosquitoes.
Using Chemicals to Control It
* Use larvicide in large breeding containers.
* Spray insecticide. It can be used as warm fogs or cold aerosols.
* Use formulas based on oil because they prevent the chemicals from evaporating.
* Use common insecticides like organophosphorus compounds (fenitrothion and malathion) and pyrethroids (bioresmethrin and cypermethrin).
Environmental Safety Measures
* Discover and remove mosquito and pest breeding areas.
* Keep rooftops and sunshades clean and well-maintained.
* Always cover water stored in containers like buckets and pots.
Importance of Health Education
Educating people about the dengue virus improves public health efforts. Using audiovisuals and big awareness campaigns are good first steps to share knowledge about the virus to individuals and large groups.
Vaccination
CYD-TDV is the first live dengue vaccine that’s been approved. It is authorized for use in 20 countries where the virus is widespread.
