Chikungunya

Causative organism: Chikungunya virus
Alternative names: Buggy Creek virus
Properties:

• Family: Togaviridae
• Genus: Alphavirus

1. A positive-sense, single-stranded RNA virus,Chikungunya virus is highly infective and disabling but is not transmissible between people.
   
2. It would most likely be dispensed as an aerosol or by the release of infected mosquitos.
3. The disabling joint pain and fever, the lack of a suitable animal reservoir in Western countries and its lack of lethality make it a very "clean" weapon that could be used against key civilian installations.
   
4. The name comes from the Swahili for "that which bends up" that is a reference to the positions that victims take to relieve the joint pain.

Vector involvement: The disease is spread by culicine mosquitoes.

Symptoms:

• Sudden severe headache, chills, fever, joint and muscle pain are the commonest symptoms.
• After an incubation period of 3-12 days there is a sudden onset of flu-like symptoms including a severe headache, chills, fever (>40°C,104°F), joint pain, nausea and vomiting.
• The joints of the extermities in particular become swollen and painful to the touch.
  
• A rash may sometimes occur.
  
• Hemorrhage is rare and all but a few patients recover within 3-5 days.
  
• Some can suffer for joint pain for months.
  
• Children may display neurological symptoms.

Diagnosis:

• Detection of antigens or antibody to the agent in the blood (serology)
• ELISA is available
• An IgM capture ELISA is necessary to distinguish the disease from dengue fever.

Vaccination (Immunoprophylaxis): A vaccine is not available.

Treatment:

• No specific therapies are available.
• Symptoms are treated, e.g. with analgesics and anticonvulsants.
• The virus is killed by common disinfectants, moist heat and drying. The vector (a mosquito) also needs to be controlled with insecticides.

Chikungunya is generally not fatal. However, in 2005-2006, 200 deaths have been associated with chikungunya on Réunion island and a widespread outbreak in India (especially in Tamil Nadu, Karnataka, Kerala, and Andhra Pradesh). Andhra Pradesh saw a huge outbreak which spread to neighbouring states. As of September 2006, after the flood and heavy rains in Rajasthan in August 2006, India, thousands of cases have been detected in Rajsamand, Bhilwara, Udaipur, and Chittorgarh districts and also in adjoining regions of Gujarat and Madhya Pradesh.

manifestations observed in a recent outbreak of Chikungunya fever in Southern India includes the following:

• Maculopapular rash
• Nasal blotchy erythema
• Freckle-like pigmentation over centro-facial area
• Flagellate pigmentation on face and extremities
• Lichenoid eruption and hyperpigmentation in photodistributed areas
• Multiple aphthous-like ulcers over scrotum, crural areas and axilla.
• Lympoedema in acral distribution (bilateral/unilateral)
• Multiple ecchymotic spots (Children)
• Vesiculobullous lesions(infants)
• Subungual hemorrhage
• Urticaria
• Acral Urticaria

Pedal oedema (swelling of legs) is observed in many patients, the cause of which remains obscure as it not related to any cardiovascular, renal or hepatic abnormalities.

Category: Medicine Notes , Microbiology Notes