Chikungunya

What is chikungunya?

Chikungunya (also known as chikungunya virus disease or chikungunya fever) is a debilitating, but non-fatal, viral illness that is spread by the bite of infected mosquitoes. It resembles dengue fever.

What is the infectious agent that causes chikungunya?

Chikungunya is caused by the chikungunya virus, which is classified in the family Togaviridae, genus Alphavirus.

How is chikungunya spread?

Chikungunya is spread by the bite of an Aedes mosquito, primarily Aedes aegypti. Humans are thought to be the major source, or reservoir, of chikungunya virus for mosquitoes. Therefore, the mosquito usually transmits the disease by biting an infected person and then biting someone else. An infected person cannot spread the infection directly to other persons (i.e. it is not a contagious disease). Aedes aegypti mosquitoes bite during the day time.

Clinical Features

Clinical presentation of Chikungunya is divided in to three phases. In Chikungunya mostly symptoms have an abrupt onset with high grade fever, single or multiple joint pains, skin rashes, headache and myalgia. Clinical presentation of Chikungunya usually follows 3 phases which are as follows:

• Acute phase : Less than 3 weeks
• Sub-acute phase : > 3 weeks to 3 months
• Chronic phase : > 3 months

Clinical presentation may be mild, moderate or severe and most of the symptoms subside within 3 weeks from the onset of symptoms. Some of the symptoms may persist for 3 months and even more. Usually 10 – 1 5 % of the patient those who present with severe Chikungunya progress to Subacute or chronic phase.

Common symptoms

• Fever
• Arthralgia/Arthritis
• Backache
• Headache
• Skin rash/Itching

Rare in adults but seen sometimes in children

• Photophobia
• Retroorbital pain
• Vomiting
• Diarrhea
• Meningeal syndrome
• Acute encephalopathy

Course of illness

Symptoms and signs are generally self limiting among most of the patients. Some of the signs and symptoms progress to Sub acute or chronic phase.

• Arthralgia
• Myalgia
• Arthritis
• Persistent Joint stiffness
• Restricted joint movement
• Painful joint movement
• Enthesopathy
• Tendinnitis
• Skin pigmentation
• Skin rash

When was chikungunya epidemic outbreak occurred in the past?

In India a major epidemic of Chikungunya fever was reported during the last millennium viz.; 1963 (Kolkata), 1965 ( Pondicherry and Chennai in Tamil Nadu, Rajahmundry , Vishakapatnam and Kakinada in Andhra Pradesh; Sagar in Madhya Pradesh; and Nagpur in Maharashtra) and 1973, (Barsi in Maharashtra ). Thereafter, sporadic cases also continued to be recorded especially in Maharastra state during 1983 and 2000.

Which are the states affected by chikungunya?

The states affected by chikungunya are Andhra Pradesh, Karnataka, Maharastra, Madhya Pradesh, Tamil Nadu, Gujarat & Kerala.

Source : National Guidelines for Chikungunya