Dengue, influenza and chikungunya are serious viral infections that are usually accompanied by severe symptoms. And since the symptoms of all three are so similar, it can be quite difficult, if not impossible, to make a conclusive identification without laboratory testing, says Dr J. Anish Anand, consultant internal medicine, Apollo Hospitals.
Dengue is a mosquito-borne viral infection causing a severe flu-like illness, sometimes leading to severe complications. The dengue virus (DEN) comprises four distinct serotypes (DEN-1, DEN-2, DEN-3 and DEN-4) which belong to the genus Flavivirus, family Flaviviridae. Once infected, humans become the main carriers and multipliers of the virus, serving as a source of the virus for uninfected mosquitoes. The virus circulates in the blood of an infected person for 2-7 days, at approximately the same time that the person develops a fever. Patients who are already infected with the dengue virus can transmit the infection via Aedes mosquitoes after the first symptoms appear (during 4-5 days; maximum 12).
A person infected by the dengue virus develops severe flu-like symptoms. Individuals should suspect dengue when a high fever (40°C/ 104°F) is accompanied by two of the following symptoms:
- Severe headache
- Pain behind the eyes
- Nausea and vomiting
- Swollen glands
- Muscle and joint pains
Symptoms usually last for 2-7 days, following an incubation period of 4-10 days after being bitten by an infected mosquito. Severe dengue is a potentially deadly complication due to plasma leaking, fluid accumulation, respiratory distress, severe bleeding or organ impairment. The warning signs to look out for occur 3-7 days after the first symptoms in conjunction with a decrease in temperature (below 38°C/ 100°F).
Warning signs include:
- Severe abdominal pain
- Persistent vomiting
- Rapid breathing
- Bleeding gums
- Blood in vomit
- Fatigue and restlessness
The next 24-48 hours of the critical stage can be lethal, and proper medical care is needed to avoid complications and risk of death.
- There is no specific treatment for dengue fever. Patients should seek medical advice, rest and drink plenty of fluids. Paracetamol can be taken to bring down fever and reduce joint pains. However, aspirin or ibuprofen should not be taken since they can increase the risk of bleeding.
- For severe dengue, medical care by physicians and nurses experienced with the effects and progression of the disease can frequently save lives. Maintenance of the patient’s circulating fluid volume is the central feature of such care.
PREVENTION AND CONTROL
- The only current method of controlling or preventing dengue virus transmission is to effectively combat the vector mosquitoes.
- Proper solid waste disposal and improved water storage practices, including covering containers to prevent access by egg-laying female mosquitoes are among other methods that are encouraged through community-based programmes.
Chikungunya is a viral disease transmitted to humans by infected mosquitoes. It causes fever and severe joint pain. Other symptoms include muscle pain, headache, nausea, fatigue and rash.
- Joint pain is often debilitating and can vary in duration.
- There is no cure for the disease. Treatment is focused on relieving the symptoms.
- The proximity of mosquito breeding sites to human habitation is a significant risk factor for chikungunya.
Several methods can be used for diagnosis. Serological tests, such as enzyme-linked immunosorbent assays (ELISA), may confirm the presence of IgM and IgG anti-chikungunya antibodies. IgM antibody levels are highest 3 to 5 weeks after the onset of the illness and persist for about two months. Samples collected during the first week after the onset of symptoms should be tested by both serological and virological methods (RT-PCR).
There is no specific anti-viral drug treatment for chikungunya. Treatment is directed primarily at relieving the symptoms, including the joint pain using anti-pyretics, optimal analgesics and fluids. There is no commercial chikungunya vaccine.
PREVENTION AND CONTROL
- During outbreaks, insecticides may be sprayed to kill flying mosquitoes.
- Basic precautions should be taken by people travelling to risk areas and these include use of repellents, wearing long sleeves and pants and ensuring rooms are fitted with screens to prevent mosquitoes from entering.
Seasonal influenza is an acute respiratory infection caused by influenza viruses which circulate in all parts of the world. There are four types of seasonal influenza viruses - types A, B, C and D. Influenza A and B viruses circulate and cause seasonal epidemics of the disease.
- Influenza A viruses are further classified into subtypes according to the combinations of the hemagglutinin (HA) and the neuraminidase (NA), the proteins on the surface of the virus. Currently circulating in humans are subtype A(H1N1) and A(H3N2) influenza viruses.
- Only influenza type A viruses are known to cause pandemics.
SIGNS AND SYMPTOMS
- Sudden onset of fever, cough (usually dry), headache, muscle and joint pain, severe malaise (feeling unwell), sore throat and a runny nose.
- The cough can be severe and can last two or more weeks.
Collection of appropriate respiratory samples and the application of a laboratory diagnostic test is required to establish a definitive diagnosis.
- Patients that are not from a high risk group should be managed with symptomatic treatment and are advised to stay at home and monitor themselves to detect if their condition deteriorates and seek medical attention if required.
- Patients that are in a group at high risk for developing severe or complicated illness should be treated with anti-virals in addition to symptomatic treatment as soon as possible.
PREVENTION AND CONTROL
- The most effective way to prevent the disease is vaccination. Safe and effective vaccines are available and have been in use for more than 60 years. Apart from vaccination and antiviral treatment, public health management includes personal protective measures like — regular hand washing, good respiratory hygiene.
How to differentiate between dengue, flu and chikungunya
- All present with fever.
- Characteristic of dengue is fall in platelets and rash.
- Flu presents with cold and cough.
- Chikungunya presents with severe joint pains. l Lab tests help in differentiation.