Dengue
Dengue or break bone fever is an acute infection caused by the virus that spreads from infected mosquitoes to humans. This infection occurs more commonly in the tropical and subtropical climatic conditions. The symptoms of dengue fever include high grade fever, headeache, vomiting, loss of appetite, metallic taste, diarrhoea, muscle pain and joint pain. The fever will last for about 2-7 days. In majority of the cases the individuals the virus does not cause any complications however in a few it leads to complications like Dengue haemorrhagic fever(DHF) and Dengue shock syndrome(DSS). Dengue fever(DF) is also known as breakbone fever as it causes severe muscle spasm and joint pain.
Causes of Dengue
It is an acute viral infection caused by RNA virus of the Flaviviridae family which spreads by Aedes aegypti mosquitoes. Dengue virus (DENV) is made of 3 structural and 7 non-structural proteins. There are four serotypes of DENV namely DEN-1, DEN-2, DEN-3, DEN-4 depending upon the presence of viral structural and non-structural proteins.
Risk Factors of Dengue
- Residing in tropical and subtropical area.
- Recent history of travel to the endemic area
- Inefficient mosquito control
- Frequent air travel
- Lack of healthcare facilities
- Stagnant water in and around the home
The risk of severe disease from a secondary infection increases if an individual is previously exposed to serotype DENV-1 contracts DENV-2 and DENV-3 or if someone is previously exposed to DENV-3 acquires DENV-2.
Previous infection with dengue virus serotype DENV-1 contracts DENV-2 and DENV-3 increases the risk of developing severe form of dengue fever.
Symptoms of Dengue
After the bite from an infected mosquito, the viral replication occurs in the blood in the circulating monocytes and macrophages and then infects the solid organs and bone marrow. The symptoms of Dengue fever range from an asymptomatic state to severe infection which includes multi-organ failure. The virus incubation period is 5-7 days.
The course follows 3 phases – febrile phase, critical phase (a hallmark of plasma leak), and convalescent phase.
The febrile phase in Dengue usually lasts for about 2-7 days and is often associated with high-grade fever, severe headache, metallic taste, loss of appetite, diarrhoea, generalized body pains, muscle pain (myalgia), joint pain (arthralgia), facial flushing, redness of the skin (erythema), some individuals may also experience sore throat (injected pharynx- pharynx appears red and irritated), bloodshot eyes (injected conjunctiva-inflammation and dilation of the blood vessels), convulsions due to high fever,
Dengue is also known as breakbone fever due to the presence of joint pains and muscle pain.
In children, younger than 15 years of age the symptoms include fever, headache, muscle pain, and joint pain associated with maculopapular rash (discolored flat and raised bumps on the skin)
The critical phase begins as early as the third day after the onset of fever in patients/individuals who are still febrile (fever). This phase causes a rapid decline in platelet count with the rise in hematocrit(HCT), and also causes a decrease in white blood cell count (leukopenia).
The signs include:
- Severe abdominal pain
- Enlargement of liver (hepatomegaly)
- Fluid accumulation ascites and pleural effusion
- Persistent nausea and vomiting
- Mucosal bleeding (bleeding from gums and mouth). This occurs mainly due to the decrease in the platelet count.
- Fatigue/ weakness
The majority of the patients improve during this phase and do not deteriorate further.
Convalescent phase
As dengue is a self-limiting infection and does not cause any complications in majority of the individuals it is generally called dengue fever. Whereas, Dengue hemorrhagic fever(DHF) is a severe form of infection in which there is an increased vascular permeability and causes plasma leakage and hemorrhage.
When the dengue viral count is high in the blood the probability of Dengue hemorrhagic fever(DHF) is also high and leads to shock – this condition is known as Dengue shock syndrome(DSS).
A few other infectious diseases like influenza, chikungunya, infectious mononucleosis, measles, rubella, and HIV seroconversion illness mimic the febrile phase of dengue fever.
Diagnosis for Dengue
Your healthcare individual would ask you a few questions and collect an appropriate patient history regarding fever, diarrhea, travel history, and any comorbid conditions, which also helps in the diagnosis of dengue fever. Your healthcare provider might also perform a tourniquet test which is a clinical diagnostic method in order to determine an individual’s haemorrhagic tendency.
Your healthcare individual might advise a few blood tests to diagnose the dengue fever which include Dengue NS1 antigen testing, Dengue IgG, and IgM. The tests might also include basic blood tests like complete blood picture to look for hematocrit, platelets, total leukocyte count and peripheral smear, CRP, liver function test, and renal function test. Your healthcare provider might as well advise a chest X-ray to look for pleural effusion and an ultrasound of the abdomen to look for ascites and hepato-splenomegaly (liver and spleen enlargement).
Treatments for Dengue
Your health care provider might advise you to get admitted to the hospital to review regularly the disease progression and to watch closely to make sure that the individual is out of the critical phase. However stable ambulatory patients might be sent home in whom hematocrit is within normal limits and might be advised to return to hospital if symptoms worsen.
Treatment mostly includes fluid replacement, with increased fluid intake with oral rehydration solution with electrolytes to replace the lost fluids. Tepid sponging and paracetamol would be helpful in case of high fever.
Hospitalized patients will require intravenous fluid replacement to maintain good perfusion and urine output. Patients will be monitored for changes in temperature pattern, fluid intake, and urine output, warning signs of decrease in platelet count, WBC, and hematocrit; any bleeding manifestations, etc.
Preventive Measures for Dengue
Currently, Dengvaxia vaccine is available for Dengue fever. Dengvaxia vaccine is given to children from 9 through 16 years of age. This vaccine shall be given only to individuals who were previously infected by the dengue virus. This vaccine is given in three doses with 3 months apart (0, 6, and 12)