Chikungunya: A Viral Infection with Fever and Joint pains

Key facts

Chikungunya and dengue are prevalent in Asia and Africa.
Both Chikungunya and dengue cause fever, joint pain, swelling, and muscle pains.
Both are viral infections, and currently, there are no antiviral medicines or vaccines available for treatment.
These infections seldom lead to fatalities.

Virus

Overview

Chikungunya is a viral disease caused by an RNA virus called alphavirus of Togaviridae family. This virus enters the human body through mosquito bite of Aedes and Anopheles genera. In Asia its outbreak was reported in 1963 with around 400,000 cases in Calcutta. This disease re-merged as a major outburst in 2005-2006 with more than 1.3 million cases in many states of India.

Why it is called Chikungunya?

The word Chikungunya originated in southern Tanzania (country in Africa) where this disease was spotted first time in 1952. In native language of Tanzania called “Makonde” the word chikungunya means “contorted or twisted posture”. The term was coined due to intense pain in joints and muscles. So, folks Chikungunya is not caused by chicken.

Map showing origin of chikungunya

TransmissionTop of Form

A mosquito that is not carrying the virus, when feeding upon blood of Chikungunya-infected person, ingest the virus along with the blood. The virus multiplies within the mosquito over a span of several days, eventually making its way to the mosquito's salivary glands. When the mosquito bites another human, it transmits the virus into the blood circulation of new host. Here, virus replicates, and its numbers reach significant levels, potentially infecting other mosquitoes biting the infected human, thus continuing the cycle of transmission.

Transmission of infection

Symptoms

Symptoms appears 3–7 days after the bite of virus-infected mosquito. These symptoms include a sudden onset of fever followed by severe joint pain and swelling, along with common symptoms such as fatigue, rashes, muscle pain, and headache. The pain may disable the person for few days, but these joint and muscle pains may extend for months.

Symptoms

The risk is higher in old age (>65 years) and in those who have certain medical conditions like diabetes, heart disease or high blood pressure.
The infection can be transferred from mother to the unborn/newborn child during pregnancy or childbirth but chances of happening this are low. But virus can transfer through placenta, during delivery or through breastfeed and such transmission is called vertical transmission.

The risk in elderly and newborns is high due to their compromised immune system. The body becomes a battleground for the virus, often delaying its natural ability to clear the infection.

Why it causes pain in joints?

The residual toxins from the virus, after the infection subsides, target the cartilage and trigger inflammation in the joints, especially in the elbow, wrist, knee, and ankle. This results in intense pain and stiffened joints, a condition also known as chikungunya arthritis. Top of Form

What is the major difference in symptoms of dengue and chikungunya?

Chikungunya:

Intense pain in joints, mainly in the hands, wrist, and knees, can persists for months even after the infection has cleared.

Dengue:

The platelet count may decrease to levels below 100,000, and in severe cases of haemorrhagic fever, it may lead to internal bleeding.

Clinical tests for Chikungunya

· The RT-PCR test can be done using the blood sample of the patient specially during first week of illness when the virus load remains high. As it is caused by an RNA alphavirus, so this test utilizes its RNA to create complementary DNA using enzyme reverse transcriptase (RT) and then amplifies it through Polymerase chain reaction (PCR). Its amplification indicates presence of Chikungunya virus in blood sample (RT-PCR Diagnostic assay).

Another test includes detection of antibodies or viral antigen in the blood. Antibody (IgM) detection-based test can be done mostly in the second week of infection because the body takes time to generate a significant number of antibodies (an immune response) against the viral antigen. These antibodies can remain in the blood for more than two months. But antibody detection test is usually less sensitive because it takes time to produce antibodies by the body, whereas, early and rapid diagnosis can be done by detection of viral antigen to help prompt disease management. It can be easily detected by using any rapid diagnostic kit.

Tests for Chikungunya

Treatment

Simon et al. (2015) have given guidelines for management of chikungunya, which includes:

Adequate rest (obviously to relive joint pains).
Hydration or increase fluid intake (to remove viral toxins from the body).
Paracetamol (to control fever).
Avoiding the use of non-steroidal anti-inflammatory drugs (NSAIDs) like Ibuprofen, Asprin, Aceclofenac etc. until dengue is ruled out. This is because dengue itself can cause hemorrhage (the flow of blood from ruptured blood vessels), and NSAIDs can further increase the risk of bleeding.

Treatment of symptoms

If the symptoms of joint pain persist even after three weeks due to synovitis (inflammation of the synovial membrane around the joints) and tenosynovitis (inflammation of tendons supporting the joints), a low dose of oral prednisolone can be taken only under the supervision of your doctor for few days (not more than 10 days).

Prevention is better than cure

Avoid mosquito bites. Note: If you are infected it become even more important to prevent mosquito bites during the first week of illness because mosquitoes can transfer the infection to other people including your family members.
Support mosquito control programs by emptying containers containing water in and around your locality where mosquitoes can breed.
Spray insecticides and use nets where required.
Wear clothing to cover exposed skin, and apply skin-friendly mosquito repellents, especially during the day time when you are outdoors.