Chikungunya and dengue fever are both mosquito-transmitted viral diseases that are endemic in Asia and Africa. Dengue may also occur in other parts of the world such as South America, Central America and the Caribbean. Both chikungunya and dengue should always be considered in case of fever in travelers returning from these countries. There is no vaccine to prevent dengue or chikungunya. Precautions taken to avoid mosquito bites can, however, reduce the risk of infection.
Similarities between Chikungunya and Dengue Fever
There are many features that are common to both the diseases such as :
- Geographical distribution. Both diseases are endemic in Southeast Asia, India, and sub-Saharan Africa.
- Incubation period (the time from infection to illness). In both cases, there is usually a sudden onset of fever about 3 to 7 days after exposure.
- Clinical course. The fever is likely to continue for about a week and may resolve spontaneously.
- Symptoms. Fever, headache, muscle pain, and rash may occur in both chikungunya and dengue. In addition, chikungunya is likely to give rise to severe and prolonged joint pains, which is one of the symptoms that distinguish it from dengue. Hemorrhagic manifestations are more likely in dengue fever.
- Vector. Both the chikungunya and dengue virus are spread by the Aedes aegypti mosquito. In addition, the Asian tiger mosquito (Aedes albopictus) may also spread the chikungunya virus. These mosquitoes bite during the day, particularly in the early hours of the morning and a couple of hours before dark, unlike the mosquitoes that spread malaria which bite at night. The Aedes mosquitoes can breed in clean as well dirty water. Aedes aegypti is more active indoors and may breed in household containers, while Aedes albopictus is more often to be found outdoors.
- Treatment. There is no specific treatment for either disease. Treatment is symptomatic.
- Prevention. There is no vaccine to prevent chikungunya or dengue. Recovery from infection usually provides life-long immunity.
Causes and Risks Factors
Chikungunya is a viral disease that is transmitted to humans by the bite of infected mosquitoes. The virus causing chikungunya fever belongs to the genus Alphavirus, of the family Togaviridae. The primary vector of chikungunya virus is usually the Aedes aegypti mosquito, but the Aedes albopictus mosquito may also be involved in transmission of the disease to humans. A mosquito gets infected with chikungunya virus while feeding on an infected person. When this mosquito bites other people, it transmits the virus to them. Monkeys and other wild animals may serve as reservoirs of chikungunya virus.
Signs and Symptoms
The incubation period can range from 2 to 12 days but is usually around 3 to 7 days. The symptoms may be similar to dengue fever hence misdiagnosis is possible. Sometimes, chikungunya and dengue may occur concurrently. In some cases, the symptoms are so mild that the infection goes undetected. Chikungunya is rarely life-threatening.
The common symptoms are :
- Sudden onset of fever.
- Fever is usually accompanied by joint pain (arthralgia). The joint pain may improve within a week or two, but it is often seen to continue over a longer period of time which may stretch to months or several years.
- Severe arthritis, often affecting multiple joints.
- Muscle pain.
- Rash – a macular or maculopapular rash, especially on the trunk and limbs.
- Hepatomegaly or enlargement of the liver.
Total recovery is common and serious complications are rare, but some patient may have :
- Eye problems.
- Neurological complications.
- Heart problems.
- Respiratory failure.
- Gastrointestinal complications.
- Chronic joint pains.
- Hemorrhagic or bleeding manifestations are rare.
- The illness may become severe in children and older patients.
- Death, though rare, may occur in elderly patients.
- Serological tests, such as enzyme-linked immunosorbent assays (ELISA) – the presence of IgM and IgG anti-chikungunya antibodies may confirm the diagnosis of chikungunya. IgM antibody levels usually peak at 3 to 5 weeks after the onset of illness and may persist for a couple of months thereafter.
- Indirect immunofluorescence.
- Reverse transcriptase-polymerase chain reaction (RT-PCR).
Causes and Risk Factors
Dengue is a mosquito-transmitted viral infection caused by the bite of infected mosquitoes. The primary vector is Aedes aegypti mosquito. Dengue may be caused by any one of the four related viruses. The 4 distinct serotypes are DEN-1, DEN-2, DEN-3, and DEN-4. It belongs to the genus Flavivirus, of the family Flaviviridae.
Besides giving rise to flu-like symptoms, it can lead to severe complications such as dengue hemorrhagic fever and dengue shock syndrome which may be potentially fatal.
Signs and Symptoms
The symptoms usually appear within a week after exposure. The clinical presentation may be similar to several other viral fevers, including chikungunya. These symptoms include :
- Sudden onset of high fever. Fever may come down rapidly within 2 to 4 days, with severe sweating.
- Muscle pain.
- Joint pain.
- Pain behind the eyes.
- Enlarged lymph nodes in the neck and groin.
- Low heart rate (bradycardia).
- Low blood pressure (hypotension).
- Dengue hemorrhagic fever is a more severe form of the illness which is characterized by signs of hemorrhage in the body. There may be bleeding gums or bleeding in the nose and petechiae or tiny red and purple spots under the skin.
- Dengue shock syndrome may show all the above symptoms, along with massive bleeding and shock.
The diagnosis is made serologically on the basis of detection of antibodies to dengue virus.
- MAC-ELISA assay – immunological M-based test.
- IgG ELISA test.
- Dengue viral plaque reduction tests
- PCR tests.
Treatment of Chikungunya and Dengue Fever
There is no specific treatment or drugs that can cure chikungunya or dengue. Treatment is mainly symptomatic and may include :
- Rest in the acute stage of the disease.
- Relief of pain and fever by acetaminophen (paracetamol) or ibuprofen.
- Chloroquine may be used for prolonged arthritis.
Prevention of Chikungunya and Dengue Fever
There is no vaccine to prevent chikungunya or dengue. Prevention may involve :
- Controlling mosquito breeding.
- By eliminating mosquito-breeding sites such as stagnant water in natural habitats as well as in household containers.
- Use of insecticides to kill mosquitoes and their larvae.
- Precautions taken to avoid mosquito bites :
- Wearing clothes that minimize skin exposure.
- Use of mosquito repellents containing DEET or icaridin on the exposed skin or on clothing.
- Sleeping under mosquito nets treated with the insecticide permethrin.
- Use of mosquito coils or insecticide vaporizers.