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Dengue & Chikungunya Viral infections

Arbo Viral InfectionsRNA viruses

Prof. Ashok Rattan, MD, MAMS, INSA DFG, WHO Lab Director

Academics, Industry: Research, Diagnosis, Public Health, Academics

Dengue• Of great antiquity, clinically known in China• Swahili “ka dinga pepo”• Along with slaves ; Africa Caribbean• In Cuba (Spanish) Dinga is Dengue (fastidious)• 4 closely related RNA viruses

– DEN 1, DEN 2, DEN 3, DEN 4– Share same geographical & ecological niche– Ss RNA, flavi virus

Dengue Virus

Mosquito Transmission: Aedes aegypti and Aedes albopictus

Transmission: Aedes mosquito• Aedes aegypti

– Urban mosquito– Needs standing water for larvae– Prefers cool, dark areas for resting– Feeds through the day, most active at dawn/dusk– Eggs do not survive winter in temperate climates

• Aedes albopictus: Asian Tiger Mosquito– Urban, periurban, rural habitats– Feeds through the day, most active dawn/afternoon– Eggs survive winter in temperate climates– Invasive- spreading in Europe and Americas

www.cdc.gov

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Course of Dengue illness

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Lumsden WH. Trans Roy Soc Trop Med Hyg 1955;49:33-57

Chikungunya Virus (CHIKV): Alphavirus

• “That which bends up” in Swahili• Togaviridae family • Single strand RNA virus, mosquito-transmitted

www.cdc.gov/ncidod/dvbid/arbor/alphavir.htm

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What is Chikungunya?• Chikungunya is a virus that is transmitted from human

to human mainly by infected Aedes albopictus and Aedes aegypti mosquitoes acting as the disease-carrying vector

• Chikungunya causes sudden onset of high fever, severe

joint pain, muscle pain and headache– 3 main presentations

• Acute: – sudden onset,– Severe, incapacitating polyarthralgia– Maculopapular rash on trunk & extremities

• Subacute:– Relapse of symptoms 2 to 3 months following initial infection– Exacerbated pain in previously affected joints

• Chronic:– Persistence of arthralgia & fatigue for > 3 months– Prevalence in 12 to 50%

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Symptoms

• Symptoms include:

Sudden onset of high feverHeadacheBack painMyalgiaArthralgia

• The symptoms will appear on average 4 to 7 days (but can range from 1 to 12 days) after being bitten by an infected Aedes mosquito

Mosquito Transmission: Aedes aegypti and Aedes albopictus

Transmission: Aedes mosquito• Aedes aegypti

– Urban mosquito– Needs standing water for larvae– Prefers cool, dark areas for resting– Feeds through the day, most active at dawn/dusk– Eggs do not survive winter in temperate climates

• Aedes albopictus: Asian Tiger Mosquito– Urban, periurban, rural habitats– Feeds through the day, most active dawn/afternoon– Eggs survive winter in temperate climates– Invasive- spreading in Europe and Americas

www.cdc.gov

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Epidemiology Chikungunya risk zones

Outbreaks of Chikungunya virus are usually found in:– Africa– Southeast Asia– Indian subcontinent and islands in the Indian Ocean

CHIKV: re-emerging disease• Initial descriptions in 1950s• 2000 Epidemic in Kinshasa, DRC,

1st in 39 years• 2001-2003 epidemic in Indonesia,

1st in 20 years• 2004 Coastal Kenya

– E226V mutation more efficiently transmitted by Aedes albopictus

– 2005 Spread to Comoros Islands • 2005-2007 Epidemic in Réunion:

35% attack rate– 266,000 cases– 0.1% mortality

• 2006 Maldives & India• 2008 Singapore• 2012 Rural Cambodia

– 44.7% prevalence– 5.3% asymptomatic

• 2012 Bhutan– 1st cases reported– Index case recent travel from

India– East/Central/South African

genotype• 2012 Papua New Guinea

– 1st cases reported

MMWR 2012; 61: 737-40www.cdc.gov/eid 2013 vol 19

Treatment and Prevention• Acute Illness

– Supportive care– NSAIDS– Case reports of short steroid courses for severe early

disease• Persistent arthralgias: no good data for treatment

– Chloroquine, hydroxychloroquine • No sig difference in efficacy for acute arthralgias

between chloroquine and meloxicam in 509 indiv in India

– Sulfasalazine, methotrexate, ribavirin, interferon-alpha• Mosquito avoidance• Vaccines in research, not licensed• Monoclonal antibodies as prophylaxis effective in mouse

models

Incubation Period

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What should I do if I suspect my patient has Chikungunya?

Chikungunya is a reportable disease. ECDC proposes the following reporting levels:

Case categories

• Possible case: a patient meeting clinical criteria

• Probable case: a patient meeting both the clinical and epidemiological criteria

• Confirmed case: a patient meeting the laboratory criteria, irrespective of the clinical presentation

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Algorithm for ascertainment of suspected Chikungunya case

Source: ECDC Mission Report: Chikungunya in Italy, Joint ECDC/WHO visit for a European risk assessment 17 – 21 September 2007

Protection

• Personal protection: DEET, Picaridin• Household prevention: Screen, Bed nets• Neighbourhood & community prevention• Vector Control

– Same as for Dengue vector control