Dengue Fever, a public health threat that´s on the rise worldwide
What is Dengue Fever and why is it considered a Public Health threat? Dengue fever is a viral infection that begins when a “Flavivirus”, also known as the dengue virus, enters the human body through a mosquito bite. Thus, this is a mosquito-borne viral infection that is mainly spread by female mosquitoes of the Aedes Aegypti family. This type of mosquito has several distinctive traits, such as having white body bands, and scales in its legs and thorax. Typically, when a person is bitten by an infected mosquito, it will start feeling sick. In this case, the person will likely develop a high fever, intense headaches, muscle pain, nausea, and vomit. Moreover, in some cases, this illness can get worse and turn into dengue hemorrhagic fever.
In recent years, dengue fever has become a rising public health threat worldwide. For example, just in the last decade, the number of reported dengue fever cases has increased 8 fold over the past 20 years. In fact, the number of reported dengue infections went from 505,000 cases in 2000, to 4.2 million in 2019. Moreover, according to the World Health Organization (WHO), half of the people in the world are now at risk of acquiring this infection. Therefore, the WHO estimates that over 390 million people become infected every year. In terms of geographic risk, dengue fever is prevalent and widespread among countries located at or near the tropics, and especially in rural areas. Nevertheless, in recent years it has also spread across countries further from the tropics, as well as cities and urban areas.
Dengue Fever Risk Factors
The factors that increase the risk of being infected by the dengue virus are the following:
- Living in or traveling through a tropical region. Living at or traveling through tropical or subtropical regions increases the risk of being exposed to the dengue virus. Most importantly, the specific regions that have the highest risk of having dengue prevalence and transmission are Southeast Asia, the Pacific Islands, Latin America, and the Caribbean.
The following factors increase the risk of developing dengue hemorrhagic fever:
- Having had a previous dengue fever infection. Indeed, a previous dengue infection increases the risk of developing dengue hemorrhagic fever and its severe dengue symptoms.
About the Aedes aegypti mosquito
There are several things to note about this mosquito. First of all, it’s important to know that its main habitats are tropical and urban settings. Second, in terms of breeding grounds, the Aedes Aegypti mosquito thrives in wet places such as old tires, discarded buckets, uncovered cisterns, and pet dishes. Third, this mosquito is a daytime feeder, with its peak biting periods being in the early morning and in the evening just before dusk. Fourth, in each feeding period, this mosquito bites many people and can thus spread the dengue virus rapidly. Finally, a key trait of this mosquito is that its eggs can survive in dry places for more than one year. Once they come into contact with water in wet surfaces, they are ultimately able to hatch.
Dengue Transmission. How is dengue fever spread?
The first thing to note is that the only two mosquito species that can carry and spread the dengue virus are the Aedes aegypti and the Aedes Albopictus. However, from these two species, the Aedes aegypti is by far the most active in spreading this viral disease. In turn, when this mosquito bites a person that is currently infected and sucks its blood, it also ingests the dengue virus. Once this happens, the dengue virus´ incubation period for the mosquito ranges from 8 to 12 days. Once this time has passed, the mosquito will start to spread the disease every time it bites a person. Consequently, the newly infected person can develop dengue symptoms 2 to 7 days after being bitten by an infected mosquito. Thus, as explained above, dengue fever is not contagious and/or spread from person to person. The dengue virus is only spread from one infected person to a mosquito (through a mosquito bite), and from this infected mosquito to another person.
Dengue virus serotypes and Dengue fever types or categories
Dengue fever is caused by a virus pertaining to the Flaviviridae family. In turn, this virus has four closely related but distinct serotypes that cause dengue: DENV-1, DENV-2, DENV-3, and DENV-4. On the other hand, in terms of dengue fever types, also known as dengue categories, the WHO recognizes the following:
Dengue fever types (Dengue categories)
- Dengue fever: This illness is usually not severe, as the body tends to recover by itself with proper care and rest. In turn, dengue fever is further split into two subcategories.
- Dengue with mild symptoms and/or no symptoms.
- Dengue with alarm symptoms: this type of dengue usually comes with a high fever (40°C/104°F), and is accompanied by two or more of the following symptoms; severe headaches, pain behind eyes, nausea, vomiting, skin rash as well as muscle and joint pains.
People who have dengue without symptoms and those who have dengue with alarm symptoms, may both develop dengue hemorrhagic fever.
- Dengue hemorrhagic fever: This illness, also known as severe dengue, has an incubation period in humans that ranges from 5 to 8 days. Unlike normal dengue, dengue hemorrhagic fever is a severe illness that may cause grave symptoms and even death. In this case, the following severe symptoms may appear: tachycardia, severe bone aches and hemorrhages, blood pressure variations, circulatory failure, and dehydration.
Dengue hemorrhagic fever was first identified during the 1950s during a dengue outbreak. Currently, it has evolved to be one of the leading causes of death in both adults and children in tropical regions.
Once a person recovers from dengue fever, it acquires lifelong immunity to the particular dengue virus serotype that caused the disease. However, this person will only have temporary and partial immunity to other dengue virus serotypes. Consequently, subsequent infections caused by these other serotypes increase the risk of developing severe dengue.
Dengue Fever Symptoms
Although dengue is a Flu-like disease that affects babies, children, and adults, it very rarely causes death. Nevertheless, dengue symptoms are frequent and bothersome. Most often, dengue symptoms start after 2 to 7 days of being bitten by an infected mosquito. In the beginning, dengue may cause initial symptoms such as a high fever (40°C/104°F), and at least two of the following symptoms:
- Muscle, bone, and/or joint pain.
- Pain behind eyes.
- Swollen glands.
- Skin rash.
In turn, most people will recover from dengue in about one week. Nonetheless, there are some cases in which symptoms will become more severe and could be potentially deadly.
Dengue Hemorrhagic Fever Symptoms
Dengue hemorrhagic fever symptoms begin to appear 3 to 7 days after the initial symptoms. Most importantly, symptoms usually start with a sudden drop in body temperature (below 38°C). Furthermore, other severe symptoms that may cause a sudden emergency are:
- Intense abdominal pain.
- Constant vomiting.
- Gum bleeding or nose bleeding.
- Blood in stool, in urine or in vomit.
- Blood under the skin, which may look like a bruise.
- Breathing difficulty and/or agitated breathing.
- Cold and/or humid skin.
- Feeling irritated.
Dengue Symptoms in Kids
Fortunately, dengue symptoms tend to be mild in kids, and especially in those who suffer from this viral infection for the first time. However, kids who have had this infection previously and become ill again may develop moderate to severe dengue symptoms. Consequently, apart from the above-mentioned symptoms, kids may also develop some of the following symptoms:
- Skin rash in thorax, arms, and legs.
- Small nose bleedings.
What are the phases or stages of a dengue infection?
The dengue fever incubation period can vary from 3 to 15 days, but most often goes from 5 to 7 days. After this incubation period, dengue usually begins abruptly following these three phases: febrile, critical, and convalescent.
- Febrile phase: it can be biphasic and usually lasts from 2 to 7 days.
- Critical phase: Dengue´s critical phase begins when the febrile phase is ending and will last from 24 to 48 hours, typically from day 5 to day 7. Most patients improve during the critical phase, although some may develop severe dengue.
- Convalescent phase: the convalescent phase of dengue fever usually starts after day seven. During this phase, the patient improves and begins to feel better. In addition, White cell count and platelet count usually start to rise.
|Febrile phase||During dengue’s febrile phase, infected patients develop a high fever. This phase usually lasts between 2 to 7 days. Typically, other symptoms such as body aches, pain behind eyes, and headaches may develop during this phase. In addition, hemorrhagic skin complications may develop due to high fever. Once the high fever comes under control, patients tend to improve.||Possible complications during the febrile phase:
|Critical phase||The critical phase develops in a fairly small number of cases. When it does occur, it starts from day 3 to day 5. During this phase, body temperature decreases to 37.5°C or even less. As a result, the production of red blood cells increases, and a pulmonary or cardiac illness may appear.||Possible complications during critical phase:
|Convalescent phase||After the critical phase which usually lasts from 48 to 72 hours, the convalescent phase begins. During dengue´s convalescent phase, there’s a general health improvement. Accordingly, people regain their appetite, gastrointestinal symptoms improve and fever completely disappears.|
Dengue Tests: How to Diagnose Dengue Fever
The most common dengue fever tests are the dengue antigen test and the dengue antibody test. Accordingly, these tests are used to find out if a person is infected with the dengue virus. In general, these two tests should be performed if your doctor suspects that you have dengue symptoms. In addition, they should be used if you have traveled recently to high-risk areas where dengue fever is prevalent. Currently, it is common practice for physicians to use a combination of the following dengue tests (blood tests) to diagnose this disease:
- Dengue molecular test (Dengue PCR test): this test is used to confirm the diagnosis of a suspected dengue case. The dengue PCR test may be used after 72 hours of initial symptom onset.
- Dengue virus antigen detection test (NS1 test): High concentrations of the NS1 antigen are found during the first dengue phase. In addition, it is found in both patients with their first dengue infection, as well as patients with a subsequent re-infection. This antigen can be found from the first day of illness onset. Thus, this test can be performed after day one of symptom onset, and up to day seven of symptom onset.
- Dengue antibody test IgM and IgG (Dengue serologic test): our immune system reacts against this infection and produces enough IgM antibodies to be detected after 3 to five days from fever onset. On the other hand, IgG antibodies are produced after 14 days of fever onset and remain in our body for life.
Dengue test methodology: to obtain a blood sample for your dengue test, the laboratory technician will draw blood from your vein. In order to do so, he will insert a needle in your vein and will extract a small amount of blood. Subsequently, he will place the blood in a laboratory vial. Unfortunately, you might feel a little pain or discomfort during this procedure. However, it is usually a quick and painless diagnostic method that should take less than 5 minutes.
Dengue Fever Treatment and Dengue Hemorrhagic Fever Treatment
Treatment of Dengue Fever without signs of alarm
Although there’s no actual medical treatment that can cure a dengue infection, medical treatment is indeed effective at controlling and managing dengue symptoms. First of all, in the case of dengue fever without alarm symptoms, treatment usually consists of staying at home and keeping hydrated. In addition, the fever and pain medication called “Paracetamol” is the only medication that should be used to control both fever and pain. Alternatively, if the patient develops diarrhea, medications such as “Loperamide” or “Hidrasec” can be used. In any case, symptoms should be monitored closely. Most importantly, the patient should call its doctor immediately if symptoms such as severe abdominal pain, profuse vomiting, bleeding, or sleepiness appear.
Dengue Hemorrhagic Fever Treatment
Similarly to the above-mentioned instance, treatment for dengue hemorrhagic fever consists of staying at home, getting plenty of rest, staying hydrated, and managing fever. However, with this grave infection, it is important to closely monitor the known alarm symptoms on a daily basis. In particular, a patient should seek immediate medical care and may be admitted to a hospital if severe abdominal pain or profuse bleeding develops. If this is the case and the patient is admitted to a hospital, treatment will focus on monitoring platelet levels and keeping the patient hydrated through an IV solution. In addition, fever should be managed with “Paracetamol”, Diarrhea with “hidrasec” or “loperamide” and multivitamins might also be used. Most importantly, if the platelet level falls beneath a certain level, a blood transfusion may be necessary.
To appropriately monitor a dengue hemorrhagic fever infection, a daily lab platelet test will be needed. With this exam, one should check that platelet levels do not drop below 60,000. If this happens, the patient should be hospitalized immediately.
How to Prevent Dengue
Dengue fever can be prevented by preventing and stopping the reproduction of the Aedes aegypti mosquito. In addition, avoiding this mosquito bite is also a viable preventive measure. Moreover, by following these recommendations we can prevent dengue fever:
- Wash frequently with soap-buckets, tanks, and cisterns, as well as any item that can serve to store water.
- Cover household items that can hold or contain water.
- Throw away junk and maintain your house junk-free.
- Always keep your house and its surroundings clean and tidy.
- Invest in a screen for your windows and doors.
- Use protective clothing such as long-sleeve shirts and pants.
- You can use insecticides that are effective against mosquitoes.
- Use mosquito repellent all over your body.
- Avoid high-risk areas where dengue is known to be prevalent.
If I have Dengue Fever, when should I seek medical care?
- Severe abdominal pain.
- Profuse vomiting.
- Breathing difficulty.
- Bleeding in gums, nose, in your vomit, or your stool.
If, on the other hand, you have dengue fever without symptoms or with mild symptoms, you should keep to the following instructions:
- Stay at home.
- Get plenty of rest.
- Take Paracetamol to manage and control your fever (following your doctor´s instructions).
- Do not take aspirin or ibuprofen.
- Always keep yourself hydrated; drink lots of water and electrolytes.
Frequently Asked Questions about dengue
Dengue fever is a disease caused by a virus called Flavivirus, which is transmitted by Aedes aegypti mosquitoes. Particularly, this type of mosquito has white body bands and scales in its legs and thorax. According to the World Health Organization, the first dengue cases were reported in Asia, Africa, and North America in 1780. In Mexico, the first dengue cases were reported in 1941. In recent decades, the incidence rate of this disease has grown rapidly.
Nonetheless, in reality, dengue cannot be spread from one person to another. Thus, the only way that the virus can spread is when a person is bitten by a mosquito that has been previously infected with the dengue virus. In other words, for dengue to be spread, a mosquito has to bite an infected person, carry the virus for several days and bite a healthy individual which in turn will become infected.
Dengue symptoms initially begin with a sudden and high fever and intense headaches. In addition, you can experience bone and muscle pain, nausea, vomit, and skin rash. Dengue fever can last up to 15 days and can become a severe disease called dengue hemorrhagic fever.
In Mexico, dengue becomes prevalent in June and remains an active threat during the summer rainy season. Consequently, dengue reaches its highest point of prevalence during August and September and usually ends its cycle in November or December.
Dengue hemorrhagic fever is the most dangerous type of dengue. First of all, it is well known that one in every 20 people who have a dengue infection will develop dengue hemorrhagic fever. Second, this type of infection is most severe as it can cause shock, internal hemorrhages, and even death in extreme situations. Finally, mothers and babies have a higher risk of developing this infection, and in general, the risk increases if you have had dengue previously.
Dengue hemorrhagic fever symptoms usually appear 24 to 48 hours after the fever has disappeared. Therefore, if you develop any of these symptoms after having a fever, go to your nearest hospital:
- Stomach pain.
- Constant vomiting.
- Bleeding in nose or gums.
- Blood presence in vomit or stool.
- A feeling of being exhausted or irritated.
In reality, there is no cure for dengue fever. However, the treatment of its symptoms can be necessary and effective. Treatment of dengue symptoms relies on getting enough rest, keeping hydrated by drinking lots of liquids, and managing fever with Paracetamol. Nevertheless, if you develop severe symptoms, you may require to be admitted to your nearest hospital.
No, you should not take aspirin when you have a dengue infection, and should only take medication that’s prescribed by your doctor. Thus, at the first sight of dengue signs or symptoms, you should call your doctor or visit your nearest hospital. This is very important because there are medications that, if taken while having dengue, can cause serious complications or may even be a cause of death. For example, aspirin acts as a blood thinner. Therefore, if you have dengue fever and are prone to bleeding, aspirin should never be taken as it increases severe bleeding risk.
Yes, dengue fever is spread by a mosquito bite, and anyone can get it, including pregnant women. Moreover, a pregnant woman infected with dengue can pass the virus to its fetus. In turn, if the fetus gets infected with the dengue virus, it can develop grave complications such as malnutrition, premature birth, or even death.
Yes, indeed; there is a dengue vaccine that is available in some countries and is manufactured by Sanofi Pasteur. In fact, this is the only dengue vaccine that currently exists and it’s called “Dengvaxia” (CYD-TDV). In the U.S., Dengvaxia was approved by the Food and Drug Administration (FDA) in May of 2019.
- Who is the dengue fever vaccine for? The World Health Organization (WHO) recommends this vaccine for people who are between 9 to 45 years old. In addition, the WHO recommends that this vaccine should only be used to persons with confirmed prior dengue virus infections. This is very important because people who receive the dengue vaccine and have not been previously infected with dengue may be at risk of developing hemorrhagic dengue if they get dengue after getting vaccinated with Dengvaxia. The dengue vaccine is given as a three-dose series on a 0, 6, and 12-month schedule.
- Is the dengue fever vaccine effective (Dengue Vaccine efficacy)? The dengue vaccine proved to be effective in randomized trials. Accordingly, its efficacy during this trial was that of 59.2% for dengue and 79.1% for hemorrhagic dengue.
- What are the common side effects of the dengue vaccine? Common side effects of the dengue vaccine include headaches, muscle pains, and pain in the site of injection.
- What is the cost of the dengue fever vaccine? The cost of the dengue fever vaccine in Mexico ranges from $2,800.00 to $4,500.00 Mexican pesos, depending on supply and demand, availability, and the specific location where it’s bought.
- How long does the dengue fever vaccine last? Although there is no definitive information about how long you will be protected from this disease after getting the dengue vaccine, we do know several things. First, the vaccine is most effective once 28 days have passed from the day you get your vaccine. Second, we know that you will be protected from a dengue infection for at least three years, and perhaps even longer.
Dengue, Zika, and Chikungunya are all viral infections that are produced when someone is bitten by an infected mosquito. Due to this fact, all three of these illnesses have the following symptoms in common: fever, headaches, as well as joint and muscle pain. Nevertheless, these three viral diseases are different in the following matter:
|Mosquito||From the Aedes aegypti and Aedes albopictus family||Aedes aegypti family||From the Aedes aegypti and Aedes albopictus family|
|Incubation period||4 – 7 days||3 – 12 days||3 – 7 days|
|Beginning of symptoms||2 – 7 days after the mosquito bite.||2 – 7 days after the mosquito bite.||4 – 8 days after the mosquito bite.|
||Treatment depends on symptoms. In general, rest, hydration, and pain management.|