Chikungunya

Introduction

Chikungunya is an infection caused by the Chikungunya virus (CHIKV), which was first identified in 1952 in Tanzania. The virus is primarily spread by the Aedes albopictus and Aedes aegypti mosquitoes, which mainly bite during the day. The name "Chikungunya" originates from the Kimakonde language, meaning "to become contorted," reflecting the severe joint pain experienced by those infected.

Signs and Symptoms

Approximately 85% of people infected with Chikungunya virus experience symptoms. The acute phase typically begins with a sudden high fever above 39°C (102°F), followed by severe muscle and joint pain. This pain is often symmetrical, affecting multiple joints in the arms and legs. Other common symptoms include headache, back pain, nausea, fatigue, and a rash that can cover over 90% of the skin in some cases.

The acute phase lasts around a week, after which most symptoms resolve. However, many individuals continue to experience joint pain in the post-acute phase (three weeks to three months) and the chronic stage (longer than three months). Chronic symptoms include arthritis, tenosynovitis, and bursitis, particularly in previously damaged joints.

Diagnosis

Diagnosing Chikungunya involves clinical, epidemiological, and laboratory criteria. Clinically, high fever and severe joint pain raise suspicion. Epidemiologically, recent travel to an area with Chikungunya presence is considered. Laboratory confirmation includes viral isolation, RT-PCR, or serological diagnosis.

Virus isolation, though definitive, takes one to two weeks and requires biosafety level III labs. RT-PCR can provide results in one to two days by amplifying Chikungunya-specific genes from blood samples. Serological tests measure Chikungunya-specific IgM levels and can detect the virus from five days to months after symptom onset.

Prevention

The most effective prevention methods include mosquito control and avoiding bites. Mosquito control focuses on eliminating standing water where mosquitoes breed. Personal protection involves using insect repellents containing DEET, icaridin, or PMD, and wearing bite-proof clothing treated with pyrethroids. Installing window and door screens can help keep mosquitoes out.

In November 2023, the USFDA approved the first Chikungunya vaccine (Ixchiq) for adults, marking a significant advancement in prevention.

Treatment

There is no specific treatment for Chikungunya. Supportive care includes rest, fluids, and medications such as nonsteroidal anti-inflammatory drugs (NSAIDs) for fever and joint pain. Aspirin is not recommended due to the risk of bleeding, and corticosteroids should be avoided during the acute phase as they may worsen the infection.

For chronic arthritis, ribavirin may be beneficial, while the role of chloroquine remains unclear. NSAIDs and simple analgesics can provide symptom relief, and methotrexate has shown benefit in treating inflammatory polyarthritis resulting from Chikungunya.

Epidemiology

Chikungunya is endemic in Africa and Asia but has caused outbreaks in Europe and the Americas since the 2000s. The disease is spread by mosquitoes in urban environments and can circulate between humans and mosquitoes during outbreaks. Genetic analysis suggests that a mutation in the virus has facilitated its spread by the Asian tiger mosquito (A. albopictus), increasing the risk of outbreaks in areas where this mosquito is present.

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Self-assessment MCQs (single best answer)

What is the primary cause of Chikungunya infection?

Which mosquitoes primarily spread the Chikungunya virus?

What is the meaning of the word "Chikungunya" in the Kimakonde language?

What percentage of people infected with Chikungunya virus experience symptoms?

Which of the following is NOT a common symptom of Chikungunya?

What is the recommended laboratory method for a rapid diagnosis of Chikungunya?

Which insect repellent ingredient is recommended for personal protection against mosquito bites?

Which vaccine was approved by the USFDA in November 2023 for Chikungunya prevention?

What type of medication should be avoided during the acute phase of Chikungunya due to the risk of worsening the infection?

Where is Chikungunya endemic?