Dengue fever is a disease that causes fever, chills, and body aches. It’s caused by the dengue virus and transmitted by mosquitoes.
This article will explain what dengue is, including how it is transmitted, the symptoms it presents, and the complications it causes. There will be a thorough description of how this infectious disease is diagnosed, treated, and prevented.
For further information directly from a healthcare professional, continue reading this article.
What is dengue?
Dengue is a virus that typically causes dengue fever in humans, and its transmission is through a mosquito. It is a very common disease since nearly half the population of the earth lives in risk areas. These are countries in the American continent, Africa, Asia, the Middle East, and islands in the Pacific Ocean. What makes these places of higher risk? Well, the hot temperature and high levels of humidity. This makes it a perfect environment for mosquitoes to live and reproduce and that way transmit the disease.
The female mosquito of the genus Aedes is the one that transmits the dengue virus infection. The main type is Aedes aegypti, but there are also others like the Aedes albopictus mosquito. The latter doesn’t transmit the disease as effectively but can resist colder temperatures. Besides the dengue fever virus, they can also transmit yellow fever, the Zika virus, and the Chikungunya virus.
There are four serotypes of the dengue virus; DENV-1, DENV-2, DENV-3, and DENV-4. After someone has one of these, they develop protection or immunity to just that type, meaning they can still have the disease again, up to four times. Each time a person gets the disease again from another type of dengue virus due to an infected mosquito, it’s worse than the last time. There can be more than one dengue serotype in a particular area. This means people need to prevent getting the infection even if they already got it before and have stayed in their community.
How is dengue transmitted?
As we already know, the dengue virus infects people through a mosquito bite. First, the mosquito needs to acquire the virus by biting a person with the infection. Then the virus replicates in the Aedes mosquito, specifically in the salivary glands, from 8 to 12 days.
Afterward, the mosquito remains infectious (contagious) for the rest of its life, which can be up to 65 days, although the average is approximately three weeks. The dengue transmission happens later to whoever they bite to feed on; despite that, not all people develop the disease.
Then there is an incubation period in which the patient doesn’t present symptoms. In that time, the virus replicates within the human body. It can take from 3 to 14 days until the symptoms begin, although the average is between 4 and 7 days. Eventually, there is the febrile phase, in which the patient has dengue fever symptoms.
Furthermore, there is a critical phase in which some patients can present complications, which will be explained further on. Finally, there is the recovery phase, in which the patient goes back to normal.
A dengue outbreak usually happens in places where there is stagnated water. Since in that latter place is where mosquitos lay eggs. This can happen because of large amounts of rain or poor hygiene of outdoor areas. For example, tires, buckets, trash cans, pots, and pools that aren’t cleaned continuously can allow mosquitos to lay eggs. Water from rain or from other sources that get in those places is perfect for their growth. In cities with poor planning and cleaning services, dengue epidemics can happen more often because of more standing water.
Dengue transmission can similarly occur to unborn children if a pregnant woman has the disease and is pregnant or passing dengue to the recently born child while giving birth to him or her. Besides, rarely do dengue transmissions happen due to blood transfusion, organ transplant, or needlestick cut.
What are the symptoms of dengue fever?
The main dengue fever symptom people have is a fever. This is the increase of the body temperature above the normal range the body has. It is a defense mechanism against microbes since most of them don’t survive the high temperature. It also helps the immunological system to work better against these microbes. In some cases, they can do more harm than good since the body cannot control it or is a very high fever.
Dengue fever usually lasts from two to seven days, and its onset is sudden and comes along with chills. In some children, the dengue fever ceases for a day and then appears again, continuing to follow that pattern. The dengue infection also comes with muscle and joint severe pain throughout the body, giving it the name of breakbone fever.
This first phase comes with many other symptoms, such as:
- Skin rash that lasts for three days approximately. It can look like tiny, not well defined red spots throughout the whole body.
- Headaches (it can be a severe headache)
- Pain behind the eyes
- Fatigue and weakness
- Lack of appetite
- Sore throat
- Mild bleeding in the gums
- Petechiae, which are small red, purple or brown spots in the skin due to bleeding under the skin.
What are the possible complications of dengue fever? What is dengue hemorrhagic fever?
The main complication of dengue is “severe dengue.” This is a condition where common dengue fever develops more severe symptoms.
Severe dengue cases include dengue hemorrhagic fever (DHF) and dengue shock syndrome; still, this is an old classification of severe cases. Today the only categories are dengue and severe dengue. Uncomplicated dengue presents the typical symptoms that were mentioned above.
Both dengue and severe dengue start the same way. The severe or critical phase (warning signs) can appear around the third or seventh day of disease onset, meaning possible severe dengue fever. It includes severe abdominal pain, vomiting, difficulty breathing, bleeding gums and nose, liver enlargement, dizziness, or extreme sleepiness.
Careful monitoring is necessary after the fever is gone for 24-48 hours. These patients with severe dengue usually develop warning signs at that time, although it can also happen a day before the fever goes away.
Severe dengue occurs as an immunologic response to Dengue Virus. This means that the immune system attacks the virus in a way that causes harm instead of benefit. In this case, the body experiences generalized body swelling. Swelling or inflammation is one of the many weapons the immune system has for battling infections.
In severe disease, inflammation occurs without control. This leads to plasma leakage. Plasma is the part of the blood that contains all the water. The “leakage” means that it escapes the blood vessels, which leaves less circulating blood.
The decrease in circulating blood is what causes shock in patients and can kill them. This is because the organs don’t get enough blood and begin to fail. It is what specialists call organ damage, and it mostly happens in the liver. The damage comes with elevated ALT or AST. These are blood markers of liver damage. Severe bleeding is also a hallmark of severe dengue since it can cause terrible hemorrhages, especially internally.
How is dengue fever diagnosed?
To help with the diagnosis, notify if you have traveled to an area where dengue is common. If the symptoms match, your doctor will order some tests to confirm. There are different types of tests: serologic, virus detection, and molecular methods.
Serologic tests evaluate the presence of antibodies in the blood sample. Antibodies are part of your immune system. This system is in charge of fighting off infections; antibodies are present to help the body get rid of the dengue virus. If antibodies are present, the body is fighting dengue or has recovered from it recently.
The test measures the antibody titer for an antibody called IgM. A titer is a measure of the elevation of your antibody levels. For this test to be positive, doctors need to take two blood samples (seven to twenty-one days apart from each other) and cath a four-fold (or a significant) increase between them of the IgM antibody to any dengue virus type. Other tests like the Plaque Reduction Neutralization Test (PRNT) can help determine the virus causing the problem, but it is not widely available. If a serologic test is negative at the beginning of the disease, it should be repeated afterward (seven days after symptoms began).
Virus detection tests use blood samples to determine the presence of the virus itself. This is useful to diagnose a dengue virus infection before the first week has passed. Seven days after symptoms onset, the test usually comes out negative and provides little information.
Molecular methods (PCR) detect the virus presence in a different but more reliable way. They are most useful in the first week of the disease. When results are positive, these confirm dengue infection. A negative PCR in the febrile phase (when there is fever), without another diagnosis, should undergo serologic testing anyway further on.
What is the treatment for dengue?
In uncomplicated dengue fever, the main treatment is bed rest and hydration. This means that patients should not engage in physical activity and should drink plenty of water.
No special drug can make viral infection shorter. In other words, no medicine is going to make the patient feel better quicker. If fever occurs, patients should take only acetaminophen. Patients must avoid Aspirin (acetylsalicylic acid, ASA) and other ASA-containing medications. This is very important because Aspirin interferes with the normal function of platelets. These are part of the blood coagulation process, and they decrease in the critical phase of dengue. Consuming Aspirin with low platelet counts can be life-threatening as they can prone to hemorrhages.
Other Non-Steroid Anti-Inflammatories (NSAIDs) such as ibuprofen and naproxen are not safe either. They can cause the same harm as Aspirin. Always remember to consult a healthcare provider before taking any medicine. Another good resource to lower the fever is tepid sponge baths. After three days of the disease, all patients should go to the doctor to look for warning signs and a follow-up.
Treatment for dengue with warning signs consists mainly of fluid reposition if the exams show evidence of leakage. Besides that, many parameters’ supervision is very important to timely treat complications if severe dengue develops. In severe dengue, treatment depends on whether there is fluid leakage or bleedings.
In bleedings, full blood transfusions may be necessary to restore lost blood. On the other hand, platelets and fresh frozen plasma transfusions are valid options to stop bleedings. Steroids, such as hydrocortisone, prednisone, and methyl-prednisone, are not effective in treating severe dengue.
What is the difference between dengue and Zika?
Dengue can be very similar to some diseases from the same viral family: the Flavivirus family. This group includes dengue fever virus, Zika, West Nile Virus, and Yellow Fever Virus, among many others. Particularly Dengue and Zika viruses can be difficult to differentiate because of their overall similarity in many aspects, including symptoms.
The most reliable way to differentiate both infections is through blood testing. However, even some tests are not reliable because of the virus similarities. Also, dengue fever varies from a mild case to a severe form, leaving many cases in between.
These different presentations make dengue similar to other diseases outside its virus family. The list includes Ebola virus, Malaria, Rocky Mountain spotted fever, Scarlet fever, or even Malaria. Thus, the importance of telling doctors about recent traveling.
Now, specifically when compared to Zika, here are the differences and similarities.
- Both Dengue and Zika transmissions occur by the bite of the same kind of mosquito. Still, there is a risk of Zika transmission through sexual intercourse, although this is not the main or most likely possibility.
- Common symptoms for both diseases include fever, headache, joint pain, general malaise, muscle aches. They typically last for seven days or less in dengue. Still, in some scenarios, Zika symptoms could length from days to weeks.
- Dengue usually appears the first week after traveling, although it could also appear in the second week. On the other hand, Zika tends to develop in the second week, within the two weeks after returning from traveling abroad. Sadly, Zika could similarly appear within the first week after returning from traveling.
- Zika virus generally presents with a red eye (conjunctivitis), which is exceptionally uncommon in dengue fever.
- Zika and Dengue both present rashes, and they are difficult to distinguish just by looking at them. Dengue rash typically involves petechiae (explained in symptoms) and hemorrhagic manifestations like bleeding gums. The skin feels soft to touch, without lumps or bumps. Zika’s rash feels like tiny lumps, and it tends to be itchy. The Zika’s rash location is in the face, chest, and extremities (including palms and soles).
How can you prevent dengue fever?
A critical aspect of dengue for health professionals is that it is preventable by various means. It is vital to inform the population in risk areas on how they can help prevent the disease.
In their households, they should avoid nearby standing waters. They can do this by covering cans that can accumulate water and other objects that accumulate water as well.
Using mosquito repellant every day and clothes that cover the skin can also prevent mosquito bites. People who travel to risk areas and then return to their countries should be aware of the hazard. The incubation period of the disease can be up to 14-days, which means a person can develop symptoms within two weeks later.
A functioning sewer system can make a big difference as water doesn’t stand in the streets permanently. Holes in the asphalt can also allow water to stay there and mosquitoes to lay their eggs. These depend on governments’ institutions and awareness of the problem.
There is also a dengue vaccine available which functions to prevent severe dengue. Doctors apply the vaccine to patients who already had dengue. If a person who has not had the disease gets the vaccine, it is at risk of developing severe dengue. This has to do with if the patient has dengue fever in the future, the immune system responds more aggressively, causing the severe form due to the vaccine.
Do you have symptoms of dengue fever?
This tool is a Dengue Fever Symptoms Checker. It gathers the most important signs, symptoms, and risk factors for this disease. Therefore, the tool will tell anybody who uses it the likelihood of their symptoms because of dengue. Using the tool is free and would only take a few minutes.