Dengue

dengue summary

Dengue is a disease caused by a virus of the genus Flavivirus, transmitted by the bite of the Aedes aegypti mosquito , with 4 serotypes: DEN1, DEN2, DEN3 and DEN4. A new strain, DEN-5, was recently described as a new serotype of the disease. This serotype is under investigation. It is endemic to tropical zones, especially in summer and rainy seasons. In Brazil, the Southeast and Northeast regions are the most affected and annually the Ministry of Health runs several campaigns, especially in the summer, alerting the population to prevent the disease.

Transmission occurs through the bite of an infected mosquito because it has already bitten another sick person. The main transmitter is the Aedes aegypti, a daytime mosquito. The insect’s saliva, when in contact with human blood, causes the virus to proliferate. The mosquito reproduces in places with clean and still water, therefore, populations that live in regions without basic sanitation or that accumulate places with clean and still water are exposed to a greater risk.

Symptoms of classic dengue include muscle aches, high fever , joint pain, vomiting, nausea, etc. In dengue hemorrhagic fever, bleeding occurs after the fever subsides . The Ministry of Health warns of some symptoms that may indicate dengue hemorrhagic fever, such as severe abdominal pain, cyanosis and spontaneous bleeding. The diagnosis is based on the patient’s clinical history and reported symptoms. Blood tests may sometimes be needed to prove the disease. Recently, research has been conducted with a focus on the development of diagnostic methods for the early detection of the dengue virus, including research on the NS1 viral protein.

The treatment is symptomatic and it is recommended to avoid the use of medicines based on acetylsalicylic acid .

Plants such as guaco, melissa and lemon balm help relieve the patient’s symptoms. It is advisable for the patient not to use plants that contain salicylate or salicylic acid in their composition. Homeopathic medicines like Eupatorium Perfoliatum 5 CH, Phosphorus 5 CH, Sulfur 5 CH can be used in dengue prevention. The Ministry of Health does not recommend the use of homeopathy to the detriment of current therapies.

The fight against dengue should be done by not leaving clean water accumulated in bottles, tiles, gutters, etc. The use of screens, repellents and insecticides also helps to prevent mosquito bites. It is also very important that you make your friends, relatives and family aware so that they take the necessary measures to prevent the disease. Many people are infected by mosquitoes that come from outbreaks far from their homes.

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Definition

Dengue is an acute infectious disease, of varying severity, caused by a virus of the genus Flavivirus, whose transmission occurs through the bite of a mosquito that occurs in tropical and subtropical countries, such as countries in Latin America, the Caribbean and Southeast Asia. There are 4 types of dengue fever DEN-1, DEN-2, DEN-3 and DEN-4. In Brazil, the 4 types of the disease have already been identified. Recently (in October 2013), researchers described a possible fifth type of the disease, DEN-5. This type is still under study by scientists.

The disease can manifest mildly or severely. In the mild form, the patient has fever and muscle aches, among other symptoms. The severe form, also known as dengue hemorrhagic fever, can lead the patient to death due to a drop in blood pressure due to hemorrhage.

Epidemiology

According to the WHO, around 390 million people are infected with the dengue virus annually around the world, approximately 96 million end up needing treatment. Infected people largely reside in tropical and subtropical regions of Asia, Africa, Latin America (Brazil, Antilles…) and the Pacific (Australia). In general, the affected areas are urban and semi-urban.

More than 2.5 billion people (according to the WHO) are directly or indirectly affected by dengue.

In general, dengue kills a few thousand people a year worldwide. In 2015, there were 4,032 deaths caused by dengue.

In early 2013 (January to April), Paraguay was particularly affected by dengue. On April 20, 2013, 45 deaths and 65,000 cases of the disease were recorded. The resurgence of dengue cases also reached neighboring Brazil. From January 1 to 23, 2013, 635,000 cases and 108 deaths were registered by the Brazilian Ministry of Health.

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In the State of São Paulo, the disease killed more than January 1 to April 17, 2015, with 122 deaths, which during the entire year of 2014.
As of November 15, 2015, about 1.5 million Brazilians suffered with dengue during the course of the year, according to the Brazilian Ministry of Health.

Sri Lanka
– A terrible dengue epidemic was observed in Sri Lanka, with more than 114,000 people infected and 315 deaths between early January and late July 2017, according to official statistics cited by the German press agency dpa . The police and the army were mobilized in the country’s capital, Colombo, to fight the mosquitoes that transmit dengue. According to the Red Cross, it is the country’s worst known epidemic.

Causes & Transmission

– Dengue is caused by an arbovirus of the genus Flavivirus. It is the most common arbovirus that affects humans, which is its vertebrate host. The dengue virus exists in four serotypes DEN-1, DEN-2, DEN-3 and DEN-4. A person with dengue serotype DEN-1 cannot, theoretically, be infected again by this serotype, since the immune system creates defenses against this form of the disease. However, the same person can get type 2 (DEN-2) and possibly type 3 or 4. Note that the order can be different, the person may be affected first type 2 (or 3 or 4) and then the type 1 etc. The same individual can therefore suffer from the 4 types of dengue more than 4 times from dengue.
– A person with dengue for the second time has a higher risk of developing a severe form of dengue (dengue hemorrhagic fever). Vaccination would be adequate to avoid the complications of the disease, and therefore, there are several researchers around the world working to find a vaccine against dengue.

Effect of climate on dengue virus transmission Dengue
virus develops and spreads more rapidly in mosquitoes at higher temperatures, and more slowly when temperatures are lower or fluctuate. These results are from a study published in 2017 and suggest that local weather conditions can have a major influence on dengue epidemics. If the outside temperature is high for an extended period of time, dengue prevention strategies should be a priority, as revealed by the scientists who conducted this study, from Southern Medical University ., in Guangzhou, China. In particular, the research team found that relatively high temperatures (23 to 28°C) resulted in faster viral growth and higher virus levels in mosquitoes. Warm conditions led to a shorter incubation period for the virus and the virus spread earlier in mosquitoes to the salivary glands, meaning more mosquitoes can infect. In contrast, in cooler conditions (at 18°C), the virus developed slowly and did not spread to the salivary glands. This study was published on December 1, 2017 in the scientific journal Frontiers in Microbiology (DOI: 10.3389 / fmicb.2017.02337).

Streaming

Dengue is transmitted through the bite of the Aedes aegypti or Aedes albopictus mosquito. In Brazil, Aedes aegypti occurs more frequently. These mosquitoes bite during the day, unlike common mosquitoes (Culex) that bite during the night. Aedes aegypti is mainly found in tropical and subtropical areas of the world, and the period of greatest expansion and transmission of the disease is during the summer, during or immediately after rainy periods.

Transmission occurs through the bite of a mosquito that became infected because it bit a sick person. During the bite, the mosquito’s saliva mixes with human blood, causing the infection of the human host. Mosquito proliferation takes place close to houses and dwellings where they have clean, still water (ideal place for reproduction). Places that accumulate water, such as old tires, beverage bottles, uncovered water tanks, bromeliads, potted plant dishes, etc., are deposits for mosquito larvae. There is no direct transmission from a sick person to a healthy person, just as there is no transmission through water, food or objects or from one mosquito to another.

In Brazil, the DEN-1, DEN-2, DEN-3 and DEN-4 types have already been identified, and in 2013, according to data from the Health Surveillance Secretariat, the DEN-4 serotype was the most prevalent in the samples studied .

Researchers from Minas Gerais discovered that the mosquito can carry two types of virus, which raises the concern of cases of dengue hemorrhagic fever. In addition, the mosquito can also carry the virus that causes another disease, chikungunya fever .

Groups of risk

Dengue affects the population as a whole, with no specific group at higher risk. In Brazil, the Midwest, Southeast and North regions are the most affected by the disease, and people who live in cities in these regions are the ones at the highest risk of contracting the disease. It is important to note that the South region, historically the region with the lowest incidence of the disease, recorded a large increase in incidence compared to 2012: 7.6 (in 2012) to 205.9 (2013). The state of PR recorded 56,173 cases of the disease, being the state with the highest number of infections in the southern region.

Places that accumulate clean water are the preferred places for the proliferation of mosquitoes, therefore, poor regions that do not have adequate basic sanitation or populations that are poorly informed about the modes of dengue transmission are at increased risk of being infected with the disease. However, as the mosquito moves across vast regions, other locations are also at risk.

Thus, the main risk group is people living in disease-endemic regions, such as tropical or subtropical areas, especially in countries in Latin America, Southeast Asia and the Caribbean. Patients who have already been infected with the virus are also at increased risk of developing the severe form of the disease.

A recent survey by the Ministry of Health found that the elderly are 12 times more likely to die from dengue . The causes are not yet fully understood, but it is believed that they may be related to the higher prevalence of chronic diseases in this population, such as diabetes . In 2013, 39.6% of deaths, that is, 61 of the 154 deaths registered due to dengue, occurred in elderly people over 60 years of age. The second age group with the highest incidence of death was 40 to 59 years old, with 26.6% of deaths.

Genetics – Africans Less Affected (Study)
A study carried out in part by the Pasteur Institute showed that Asians and Europeans are more likely to suffer from severe dengue .in English) than Africans for genetic reasons. Dengue is a viral disease transmitted by endemic mosquitoes, especially in tropical and subtropical regions of East Asia and Latin America, but the virus has spread in recent years also in North America and Europe. In some severe cases, dengue virus can lead to death after fatal dengue shock syndrome. Researchers had long wondered why dengue was more prevalent in Latin America and Asia than in Africa, which is also located in the tropics and subtropics. The researchers identified two genes related to blood vessel inflammation that confer risk of severe dengue and four genes related to metabolism that affect risk of classic dengue. The researchers found that Africans have genes that protect them more against severe dengue than Europeans. The latter, however, were less likely to suffer from normal or classic dengue. Asians had a significant risk of suffering from normal dengue. This study was published on February 15, 2018 in the scientific journalPLOS Neglected Tropical Diseases (DOI: 10.1371/journal.pntd.0006202).

Symptoms

First, it should be noted that symptoms appear in about 40 to 50% of people infected with the dengue virus. In other words, 50-60% of people bitten by an infected mosquito have no symptoms (asymptomatic).

The incubation period for the virus lasts from 3 to 15 days after the bite. The first symptoms of classic dengue are: high fever (from 38⁰ to 40⁰C), headaches , fatigue, body aches, muscle and joint pain, eye pain, nausea, vomiting, red spots on the body, abdominal pain (mainly in children), among other symptoms. These symptoms can last up to a week, after which time, fatigue and indisposition may persist.

hemorrhagic dengue

In hemorrhagic dengue, the first symptoms are similar to those of classic dengue and last from 3 to 4 days. After this period, the fever subsides and hemorrhages appear throughout the body, mainly in the gums, nasal cavities, gastrointestinal and genital hemorrhages. These hemorrhages can damage many internal organs and lead to death. Patients who have already been infected by the virus also have an increased risk of developing the severe form of the disease (dengue hemorrhagic fever). The Ministry of Health warns of the following signs, which may be indicative of dengue hemorrhagic fever:

  1. Intense stomach pain (resistant to standard treatment) or abdominal pain
  2. Restlessness or lethargy (drowsiness)
  3. Persistent vomiting, with or without blood
  4. Fast or weak pulse
  5. Hepatomegaly (liver enlargement) painful
  6. Cold extremities, pale, cold, clammy skin
  7. Pressure drop (hypotension)
  8. Bleeding from the nose, gums or under the skin
  9. Cyanosis
  10. red spots on the skin
  11. Excessive thirst and dry mouth
  12. breathing difficulties

In addition, the Ministry of Health established a classification that allocates the patient into 4 groups according to their symptoms. This risk classification allocates patients for priority care. See the chart below:

This classification helps and facilitates the treatment of patients who arrive at health centers and hospitals.

Risk of dengue hemorrhagic fever and immunity

It is important to know that people who have been victims of dengue in the past, caused by one of the five serotypes of the dengue virus, have an increased risk of developing dengue hemorrhagic fever in case of a new infection by one of the other 4 serotypes. For example, a person who suffered from dengue by the DEN1 virus runs a greater risk of suffering from dengue hemorrhagic fever in case of being bitten by a mosquito carrying the DEN2, 3, 4 or 5 virus, compared to a person who has never suffered from dengue. Each serotype of the virus can lead to dengue hemorrhagic fever.

However, once a person has been contaminated by a type of dengue virus serotype, he acquires lifelong immunity against this type of virus. For example, a person who has suffered from dengue caused by the virus serotype DEN1 in the past will not suffer from dengue again by the same serotype. This person can, however, suffer from dengue in the event of being bitten by a mosquito that carries serotypes DEN2, DEN3, DEN4 or DEN5, provided that he has never suffered from one of these forms of dengue. Theoretically, a person can suffer from dengue a maximum of 5 times in his life, one for each serotype of the virus.

Diagnosis

The diagnosis of dengue is made clinically, that is, based on the patient’s clinical history, blood tests, which indicate the type and severity of the disease, and specific tests. To identify which type of dengue the patient has, a serology is performed after the 4th day of infection. Other complementary tests that can be performed after the onset of symptoms are virus isolation, detection of antigens in fixed tissues, hemagglutination inhibition test and RT-PCR (Real Time PCR). These tests are more specific and serve to confirm the infection.

For dengue hemorrhagic fever, there are some tests that can be done such as the loop test, platelet count and red cell count. It is important that dengue hemorrhagic fever is diagnosed quickly, because if not treated, it can lead to death. According to the World Health Organization (WHO), there are 4 criteria that facilitate the diagnosis of dengue hemorrhagic fever:

  1. Fever from 2 to 7 days.
  2. Increased vascular permeability, which is expressed by plasma leakage, hemoconcentration and cavity effusions.
  3. Thrombocytopenia (platelets < 100,000/mm³).
  4. Tendency to hemorrhage.

Researchers from the University of São Paulo (USP) recently developed a methodology for identifying the dengue virus in saliva and urine samples and the result comes out in up to 3 hours. The diagnostic method is being tested so that it can be used on a large scale, since it is faster than the blood test.

The rapid test uses immunochromatographic methodology and identifies and differentiates IgG and IgM immunoglobulins. In this exam, any one of the 4 serotypes of the disease is identified, with a sensitivity of 99% and specificity of 98%.

Another test looks for the NS1 viral protein, which arises 1-3 days into the illness. This test indicates acute and active disease in the patient. The test has a sensitivity of 70% when compared to PCR. The NS1 test is indicated in cases of early diagnosis.

Rapid diagnosis has gained prominence as it facilitates the identification of the disease and which circulating serotypes are most present in the population. In addition, the faster the disease is identified, the better the management of dengue, even preventing its transmission and deaths.

Complications

Patients with untreated dengue have a mortality rate of 30%. Patients with dengue hemorrhagic fever should be treated immediately, as they are at risk of dying. One particularly important complication is called Dengue Shock Syndrome. The patient has a weak pulse, restlessness, pallor, and loss of consciousness. There are neurological complications such as delirium, drowsiness, depression , coma, irritability, psychosis, dementia, amnesia, paralysis and signs of meningitis. It is important to mention that patients who have already been infected by the virus also have an increased risk of developing the severe form of the disease (dengue hemorrhagic fever).

Other complications affect the cardiorespiratory system and can even cause liver failure, gastrointestinal bleeding and pleural effusion. If the patient is not treated quickly, he may die. Other complications include damage to the lungs and heart due to the hemorrhagic shock caused.

Treatments

The treatment for dengue has the function of combating the symptoms of the disease, such as fever , malaise, vomiting, muscle pain, etc. The patient is advised to rest and drink plenty of fluids.

The use of medications based on acetylsalicylic acid, such as aspirin, is contraindicated in cases of suspected dengue, since they facilitate bleeding. Before using any medicine, it is important to consult a doctor so that he can indicate the best treatment.

The use of insecticides against mosquitoes is still a matter of debate. Experts say these products are harmful to the environment, while others point out that mosquito strains are already resistant to the chemicals. There is also the possibility of using larvicides to kill mosquito larvae.

Experts warn that the treatment of dengue is more complicated in obese patients. This happens because, during the infection, patients have greater capillary permeability, which causes blood to pass from the vessels to the tissues. People with a high body mass index have capillaries that are more prone to this leakage into tissues, and this can get worse with dengue fever and cause complications such as too much fluid in the lungs.

There is no specific treatment against dengue. In some countries (Mexico, Philippines, Brazil), there is a vaccine commercially available, marketed by Sanofi Pasteur.

Read: Brazil is the third country to approve the vaccine against dengue, after Mexico and the Philippines

Herbal medicine

As well as conventional treatments, the use of medicinal plants has the function of combating the symptoms of dengue.

Plants that are commonly used to combat these symptoms are horsetail , weed, melissa , guaco , lemon balm and picão . With these herbs, tea is made and administered to the patient. It is important that, before using any herbal medicine or medicinal plant, the doctor is consulted and is aware.

It is important to mention that if the person has suspected dengue, they should avoid using plants of the genus Salix, since they contain salicylic acid and salicylate in their composition.

Tips

Some tips may be useful in the case of dengue:

– If you suspect dengue symptoms, do not use any medicine based on acetylsalicylic acid (such as aspirin).

– Consult a doctor to diagnose the disease and prescribe treatment.

– To avoid contagion, do not leave still and clean water, as they may be breeding grounds for the transmitting mosquito.

– Use sand or coffee powder in the saucers of the potted plants to avoid water accumulation. Avoid leaving objects that accumulate water exposed in the rain.

– Always keep the water tank covered and do not let rainwater accumulate in the gutters and roof tiles.

– Wash, weekly inside, with brushes and soap, tanks used to store water.

– Put rubbish in plastic bags and cover the bins. For more details on prevention, see the following topic.

– Advise your neighbors, friends and family to adopt preventive measures against the disease. Many people contract dengue fever from outbreaks that are far from their home. General awareness is the best measure to combat and prevent dengue.

– Welcoming health agents who come by periodically to check for outbreaks and fumigate homes.

Prevention

The mosquito that transmits dengue reproduces in clean, still water, so to prevent its proliferation, avoid keeping still, clean water. Places where water normally collects like potted plants, old tires, empty bottles, etc. should be monitored and covered. Use window screens and repellents to avoid mosquito bites. The use of insecticides also helps to fight the dengue mosquito.

Also read: 10 tips to fight dengue

Jeanne Kenney
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I’m a stylist trainer, a content creator, and an entrepreneur passion. Virgo sign and Pisces ascendant, I move easily between my dreams, the crazy world I want, and my feet on the ground to carry out my projects.

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