- Clinical science
Dengue is a viral disease transmitted by mosquitoes (especially Aedes aegypti) and is widely distributed throughout the tropics and subtropics. Dengue classically presents with high fever, headache, body aches, exanthem, and generalized lymphadenopathy. Symptoms usually subside within one week. Some cases progress to the more severe dengue hemorrhagic fever (DHF) with thrombocytopenia, spontaneous bleeding, and potentially shock (dengue shock syndrome). Treatment is supportive. A vaccination is available for use in children, living in endemic areas, with confirmed prior dengue virus infection.
- Distribution: tropical regions; worldwide, particularly Asia (e.g., Thailand)
- Most common viral disease affecting tourists in tropical regions
- ∼ 400 million infections per year worldwide
Epidemiological data refers to the US, unless otherwise specified.
Classic dengue fever
- Incubation period: 2–14 days
- Children are usually asymptomatic
- Starts with fever and malaise that lasts ∼ 1 week
- Severe arthralgia and myalgia; (often referred to as “break-bone fever”)
- Severe headache and retro-orbital pain
- Maculopapular, measles-like exanthem (typically appears 2–5 days following fever)
- Generalized lymphadenopathy
If symptoms appear more than 2 weeks after returning from a dengue-endemic region, it is very unlikely that dengue is the cause!
Dengue hemorrhagic fever (DHF)
- Occurs in 1–2% of cases
- Generally develops as the initial fever subsides (∼ 1 week after onset)
- Temperature change: ranges from hypothermia to a second spike in fever
- Abdominal pain, vomiting
- Changes in mental status (e.g., confusion)
- Hemorrhagic manifestations; (e.g., petechiae, epistaxis, gingival bleeding)
- Positive capillary fragility test 
- Increased vascular permeability; → signs of pleural effusion; and/or ascites
- Dengue shock syndrome (DSS): DHF + shock
Dengue hemorrhagic fever is more frequent in individuals who experience a repeat infection with a second serotype, especially serotype 2!
Chikungunya fever 
- Epidemiology: mainly occurs in the tropical and subtropical regions
- Pathogen: (togavirus)
- Transmission route: mosquitoes (Aedes aegypti and Aedes albopictus), possibly leading to coinfection with dengue
- Clinical features
- History of recent travel to tropical and subtropical regions
- Serology and RT-PCR
- Treatment: supportive
- Prognosis: Most individuals fully recover within a week.
The differential diagnoses listed here are not exhaustive.