Introduction
- According to the World Health Organization (WHO), the global incidence of dengue cases increased by 8-fold over the last 2 decades, predominantly affecting the younger age group
- As of February 2024, an increase of 189% compared to 2023’s statistics was reported in the World Health Organization (WHO) Pan American Health Organization (PAHO) region
- An increase in the number of cases was reported in Brazil, French Guyana and Thailand
- In the region of the Americas, an increase of 157% in 2024 compared to 2023 was reported, with 0.1% severe cases and 0.015% case fatality rate
- As of February 2024, an increase of 189% compared to 2023’s statistics was reported in the World Health Organization (WHO) Pan American Health Organization (PAHO) region
- Dengue is endemic in >100 countries in the WHO regions of Africa, the Americas, the Eastern Mediterranean, South-East Asia and the Western Pacific, with the global incidence rate of symptomatic cases coming predominantly from Asia (~70%)
Etiology
- Dengue infection is caused by the Dengue virus, which belongs to the family Flaviviridae
- There are 4 serotypes (DENV-1, DENV-2, DENV-3, DENV-4)
- Each serotype provides specific lifetime protective immunity against reinfection of the same serotype, but only temporary (within 2-3 months of the primary infection) and partial protection against the other serotypes
- Second dengue infection with a different dengue serotype are at increased risk for severe dengue
- The fifth serotype, DENV-5, is a new variant that follows the sylvatic cycle (transmission of dengue virus to non-human primates) while the other 4 serotypes are transmitted between humans
Pathophysiology
- It is transmitted to humans through the bites of infected Aedes mosquitoes
- Primarily transmitted by female Aedes aegypti, a tropical and subtropical species
- Other outbreaks were secondary to A albopictus, A polynesiensis, A scutellaris
- Humans are the main host of the virus
- After 4-10 days of incubation period, illness begins immediately
Signs and Symptoms
Phases of Dengue Infection
Febrile Phase
- Patient suddenly develops high-grade fever that commonly lasts for 2-7 days and is associated with facial flushing, skin redness, generalized arthralgia, myalgia, headache, anorexia, nausea, vomiting
- May also be accompanied by sore throat, injected pharynx, conjunctival injection, mucosal/gastrointestinal bleeding, tender hepatomegaly
- Likelihood of dengue infection is increased by a positive torniquet test and progressive decrease in total white blood cell (WBC) count
- Progression to critical phase should be recognized promptly by monitoring for warning signs and other clinical parameters
Critical Phase
- Occurs on days 3-7 of illness and usually lasts for 1-2 days
- Patient’s temperature lowers to ≤37.5-38oC and may have increase in capillary permeability concurrent with increase in hematocrit level
- Patient may develop pleural effusion, ascites, shock, organ impairment, metabolic acidosis, disseminated intravascular coagulation which may lead to severe hemorrhage
- Depends on the degree of plasma leakage and the volume of fluid therapy
- Other patient may proceed with this phase even without defervescence
- Changes in the full blood count may be the only guide to determine the onset of plasma leakage
Recovery Phase
- Two to three days after critical phase has been successfully surpassed
- Patient may develop rashes or “isles of white in the sea of red”
- Improvement in appetite and general well being
- Patients may present with respiratory distress due to massive pleural effusion and ascites if excessive intravenous (IV) fluids were given