International Global Health Blog

Dengue Fever and The Tropics

International Global Health

What is Dengue fever?
Dengue (pronounced DEN-gee) fever is a human virus transmitted by the Aedes aegypti mosquitoes which are very common in tropical and subtropical areas of the world. The World Health Organization has ranked this virus the most rapidly spreading mosquito-borne viral disease. The transmission cycle of dengue is from human, to mosquito, to human.
When a mosquito bites a person who is infected with dengue, it takes approximately 10-14 days for that mosquito to transmit the virus to another person. Meanwhile, the virus replicates within the mosquito until is reaches its salivary glands. The virus is then injected via the mosquito’s saliva into another human when it bites.
There are four different specific serotypes (strains) of dengue fever (DV-1, -2, -3, -4), and prior infection of one strain will make someone more susceptible to developing a more serious form of the virus, dengue haemorrhagic fever (DHF), if subsequent infections occur.
Signs and Symptoms of Dengue and Dengue Haemorrhagic Fever:
Dengue fever is a self-limiting virus, and will resolve on its own. However, DHF has a mortality rate of up to 50% if left untreated.
Following a dengue infection, there is an incubation period of up to 7 days. Some people remain asymptomatic during this time, however most will experience classic symptoms of dengue fever. The symptoms may include:
  • Sudden onset of fever
  • Chills
  • Rash and flushing
  • Headache
  • Retro-orbital pain (pain behind the eyes)
  • Severe myalgia (muscle pain): back, arms, legs and arthralgia (joint pain)
  • Loss of appetite, abdominal pain, nausea and/or vomiting
  • General malaise
  • Lymphadenopathy
  • Bleeding gums/nose
  • Low platelet count and petechiae rash
Dengue Haemorrhagic Fever is similar to Dengue fever, however after the initial period of febrile onset, it progresses to become more serious. Signs of plasma leakage develops, along with haemorrhages (hematuria, gastrointestinal bleeding) and symptoms of circulatory failure. This must be treated rapidly, or it may develop into dengue shock syndrome.
The most common laboratory blood test to detect dengue fever is serum Dengue NS1 Antigen. This protein is detectable within 24 -48 hours and up to 9 days following the onset of symptoms.
  •  A positive NS1 antigen test confirms an acute Dengue infection.
  •  A negative NS1 antigen may indicate that the specimen was taken less than 24 hours following infection, or after more than 7 days post infection.
  •  A false positive NS1 antigen test may be due to an active infection of other viruses such as West Nile or Yellow Fever virus.
If an NS1 test is negative, and the specimen was collected more than 7 days after the onset of symptoms, further testing for Dengue IgM and IgG antibodies would be required.
  • Treatment for Dengue fever is non-specific and typically involves symptom management.
  • Conventional pain relief with paracetamol and anti-pyretics.
  • Intravenous fluid if there is dehydration and the inability to ingest fluids.
  •  Avoid aspirin and all other medications that can cause blood thinning. Turmeric, fish oil, and other herbal and nutritional supplementations may also have blood thinning effects and ceasing these should be discussed with your healthcare professional.
  • Optimal fluid therapy and bleeding control are essential if the illness progresses into Dengue Haemorrhagic Fever.
  • There is emerging evidence that Papaya leaf juice may be beneficial in increasing platelet counts.
  • Platelets thrive off Vitamin C, so supportive therapy with Vitamin C may aid in increasing platelets during the active stage of infection.
Dengue Tips:
  • Always ensure you are wearing mosquito repellent if you are in tropical or subtropical areas.
  • Ensure there is no stagnant water around, as even puddles can harbour mosquitoes. Pet bowls, pots, bins, containers, and even gutters should be emptied or covered.
  • Use mosquito nets, and mosquito screens.
  • Some essential oils act as natural mosquito repellent, burning these or placing them in a carrier oil to apply topically may be beneficial: Neem, Eucalyptus, Lemon, Tea tree, Mint, Citronella, Holy Basil

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