Know the difference between dengue and flu symptoms

At some point, the symptoms of dengue and flu may be the same: headache, body and joint pain, fever and malaise. Although both diseases are viral, there are other signs that differentiate them, especially those that indicate a possible progression to more serious conditions. As Brazil faces an increase in the number of dengue cases at the beginning of 2024, it is important to know these symptoms to help identify the disease.

“The main similarity between dengue and influenza is the sudden onset of fever, usually the first manifestation of both diseases, and pain behind the eyes. The main difference is the respiratory symptoms that appear in the first few days of influenza symptoms, such as runny nose, productive cough and painful swallowing, in addition to the red spots on the skin that typically occur in dengue fever around three to five days”, he explains. the infectious disease specialist and medical manager of Clinical Development at Butantan, Érique Miranda.

According to the infectious disease specialist, the duration of symptoms is also a difference between diseases.

“I believe that the duration of symptoms is a little longer in dengue, in which prostration and muscle pain can last up to a week”, he highlights.

Dengue is caused by the bite of a female mosquito Aedes aegypti, which essentially inhabits urban and domestic areas, where it essentially feeds on human blood. Mosquitoes proliferate in hot and humid environments and lay their eggs in artificial breeding sites such as containers with stagnant water, tires, plant pots, among others.

How the A. aegypti It is a vector of the four dengue viruses (DENV-1, DENV-2, DENV-3, DENV-4), as well as the Zika and chikungunya viruses. If it bites someone infected, it will be able to transmit the pathogen to other people.

Influenza, in turn, is caused by the virus Influenza, which generally circulates in the Southern Hemisphere in the winter months, between June and September – therefore, flu vaccination usually takes place before this period. As influenza frequently mutates, every year the World Health Organization (WHO) defines the three strains that will make up the vaccines for each hemisphere, according to the viruses that circulated most in the previous year. In 2024, for the southern hemisphere, the following strains were determined: A/Victoria/4897/2022 (H1N1); A/Thailand/8/2022 (H3N2); and B/Austria/1359417/2021 (B/Victoria lineage).

Dengue symptoms x flu symptoms

The first symptoms of dengue are high fever, pain in the body and behind the eyes, redness of the skin and fatigue. They begin, on average, five days after the mosquito bite, a period called incubation, and can last from two to seven days.

At this stage, the disease is classified as classic dengue or dengue without warning signs and can be controlled with intense hydration and medications such as dipyrone or paracetamol to control the pain (some medications need to be avoided), until it disappears in a few days.

Other more specific symptoms may appear later, especially when the fever stops around the fifth day. This is the phase of dengue with warning signs, a name given by the World Health Organization (WHO) as it indicates the severity of the clinical condition. At this time, it is important to have medical supervision. In severe dengue, which is the most worrying, there is a greater systemic inflammatory reaction, which alters blood clotting and causes fluid loss. This phase usually requires hospitalization.

Flu symptoms usually appear suddenly and include fever, sore throat, cough, body aches and headache. It is common for them to disappear spontaneously in approximately seven days, although the cough, malaise and fatigue may persist for a few weeks.

In healthy adults, the clinical picture can vary in intensity, while in children the temperature can reach higher levels, with enlarged cervical lymph nodes and bronchitis or bronchiolitis, in addition to gastrointestinal symptoms, being common. In the elderly, it is common to have a fever, although the temperature does not reach very high levels, according to the Ministry of Health.

Dengue symptoms without warning signs

• High fever (40°C);
• Splitting headache;
• Pain behind the eyes;
• Nausea;
• Vomiting;
• Red spots on the skin.

Dengue symptoms with warning signs

• Severe abdominal pain;
• Persistent vomiting;
• Panting;
• Bleeding of mucous membranes;
• Fatigue;
• Vomiting blood;
• Dehydration and feeling of dry mouth;
• Pale skin;
• Weakness;
• Somnolence;
• Excessive tiredness;
• Decrease in body temperature;
• Sudden increase in hematocrit (percentage of red blood cells);
• Abrupt drop in platelets;
• Hypothermia.

Symptoms may worsen after the first week and become worse in a small fraction of people.

Severe dengue symptoms

• Dengue hemorrhagic fever (extravasation of blood plasma, which causes severe bleeding);
• Dengue shock syndrome (circulatory collapse and multiple organ failure);

Flu symptoms

• Fever;
• Runny nose;
• Sore throat;
• Cough;
• Body ache;
• Headache;
• Joint and muscle pain;
• Chills;
• Malaise;
• Headache;
• Diarrhea;
• Vomiting;
• Fatigue;
• Prostration;
• Hoarseness;
• Red, watery eyes.

Vaccination

This year, a vaccine against dengue was incorporated into the National Immunization Program (PNI), of the Ministry of Health. With reduced distribution, vaccination was only recommended for children and adolescents. The Butantan Institute is developing a new vaccine candidate against dengue, with a single dose, in the final phase of research. Its results must be presented to the National Health Surveillance Agency (Anvisa) by the end of 2024.

In Brazil, the vaccination campaign promoted by the PNI offers the influenza vaccine produced at the Butantan Institute. Proven to be safe and effective, the vaccine has been part of the SUS list of vaccines since 1999, helping to reduce the transmission of the virus and the number of serious cases and deaths. In 2021, the vaccine joined the WHO’s list of pre-qualified vaccines, which means international validation of Butantan’s Good Manufacturing Practices.

Follow the “Governo de São Paulo” channel on WhatsApp:
https://bit.ly/govspnozap