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Chikungunya an update
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CHIKUNGUNYA AN UPDATE
Dr.T.V.Rao MD
DR.T.V.RAO MD 1
• Manifest with Crippling Arthritic disease of sudden onset.
• Name is derived from Swahili – Chikungunya meaning that which bends up
• Virus isolated in 1953 from serum and Aedes mosquitoes and Culex spp
WHAT IS CHIKUNGUNYA
DR.T.V.RAO MD 2
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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 (later referred to as Aedes mosquitoes) acting as the disease-carrying vector
• Chikungunya causes sudden onset of high fever, severe joint pain, muscle pain and headache
• As no vaccine or medication is currently available to prevent or cure the infection, control of Chikungunya involves vector control measures and encouraging people to avoid mosquito bites
DR.T.V.RAO MD
EMERGING DISEASE
• Change in vector distribution due to global warming/ changing weather patterns
• Endemicity to epidemic
DR.T.V.RAO MD 4
• Isolated in Aedes aegypti mosquitoes and man in 1952 in Tanzania
• Appeared in India in 1963
• Major epidemic outbreaks in Calcutta, madras and other areas
• Manifested with Major epidemics till 1973
HISTORY
DR.T.V.RAO MD 5
CURRENT DISTRIBUTION OF
CHIKUNGUNYA
DR.T.V.RAO MD 6
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CHIKUNGUNYA RISK ZONES
Outbreaks of Chikungunya virus are usually found in:
• Africa
• Southeast Asia
• Indian subcontinent and islands in the Indian Ocean
DR.T.V.RAO MD
WHAT IS IMPORTANT IN CHIKUNGUNYA?
• Togaviridae alphavirus
• RNA virus able to evolve rapidly and expand vector
• Endemic in Africa and Asia, especially India
• Vectored by Aedes species (albopictus, aegypti)
DR.T.V.RAO MD 8
• Family – Togaviridae
• Genus - Alpha virus
• Chikungunya viral infection manifests with febrile illness
CHIKUNGUNYA VIRUS
DR.T.V.RAO MD 9
CHIKUNGUNYA VIRUS
• Enveloped virions
spherical, 60 to 70
nm in diameter
positive-sense,
single-stranded RNA
genome, ca. 11.7
kilobases long.
DR.T.V.RAO MD 10
CHIKUNGUNYA VIRUS
• Two changes to the
structure of E1 Makes
the virus more likely
to enter mosquito
cells and replicate
after the insect has fed
on the blood of an
infected person.
DR.T.V.RAO MD 11
EPIDEMIOLOGICAL TRIAD
AGENT
HOST ENVIRONMENT
VECTOR
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EPIDEMICS OF CHIKUNGUNYA
Large epidemics were recognized in Transvaal of South Africa, Zambia, India
and South east Asia, Philippines.
DR.T.V.RAO MD 13
• Out breaks occur during rainy season with increasing densities of Aedes aegypti mosquito
• Mosquitos bites infect the Humans
• Laboratory acquired infection can also occur
OUT BREAKS OF CHIKUNGUNYA
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RECENT HISTORY • 2005-2007 epidemic in
India 1.4 million
infected in 2006, 56K
infected 2007 Cases
continuing to be
reported every month
• Outbreak in Italy in
2007 OMG!
DR.T.V.RAO MD 15
NATURAL CYCLE
• Aedes mosquitoes
• Feed in daytime
• Breed in stagnant
water
• Small puddle
• Reservoir
• Primates
• Transient viremia 3-7
days DR.T.V.RAO MD 16
CYCLE OF INFECTION
DR.T.V.RAO MD 17
OTHER VECTORS • Both Ae. aegypti and Ae. albopictus have been implicated in
large outbreaks of Chikungunya. Whereas Ae. aegypti is confined within the tropics and sub-tropics, Ae. albopictus also occurs in temperate and even cold temperate regions. In recent decades Ae. albopictus has spread from Asia to become established in areas of Africa, Europe and the Americas.
• In Africa several other mosquito vectors have been implicated in disease transmission, including species of the A. furcifer-taylori group and A. luteocephalus. There is evidence that some animals, including non-primates, may act as reservoirs
DR.T.V.RAO MD 18
• Incubation 3 – 12 days
• Fever may rise to 1030c to 1040c with rigors
• Viremia lead to fever.
Fever leads to release of large amount of Interferons
CLINICAL FEATURES
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CLINICAL EVENTS IN
CHIKUNGUNYA
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CLINICAL MANIFESTATIONS
• Fever,
• Crippling Joint pains
• Lymphadenopathy
• Conjunctivitis
• A Maculopapular rash
• May lead to hemorrhagic manifestations,
• Fever is biphasic with remission after 1 - 6 days of fever.
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CLINICAL DISEASE • Significant
morbidity, minimal mortality
• Fever, rash, nausea, fatigue, arthralgia lasting days to weeks
• Arthritis may be long-term sequellae
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• In India but not in Africa, patients presented with Inguinal lymphadenopathy and red swollen ears, and are observed as part of clinical picture.
HOW SOME INDIAN PATIENTS
PRESENTED
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DIAGNOSIS OF CHIKUNGUNYA
( WHO )
• Several methods can be used for diagnosis. Serological tests,
such as enzyme-linked immunosorbent assays (ELISA), may
confirm the presence of IgM and IgG anti-Chikungunya
antibodies. IgM antibody levels are highest three to five weeks
after the onset of illness and persist for about two months. The
virus may be isolated from the blood during the first few days of
infection. Various reverse transcriptase–polymerase chain
reaction (RT–PCR) methods are available but are of variable
sensitivity. Some are suited to clinical diagnosis. RT–PCR
products from clinical samples may also be used for genotyping
of the virus, allowing comparisons with virus samples from
various geographical sources.
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• The primary differential
diagnosis of
Chikungunya, should
be made from Dengue,
and O’Nyong nyong
fevers
• Chikungunya manifest
with Myalgia rather
than Arthritis.
DIAGNOSIS
DR.T.V.RAO MD 25
LABORATORY CRITERIA Laboratory criteria: at least one of the following tests in the acute phase:
• Virus isolation
• Presence of viral RNA by RT-PCR
• Presence of virus specific IgM/IgG antibodies in single serum sample collected
• Seroconversion to virus-specific antibodies in samples collected at least one to three weeks apart
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MICROBIOLOGICAL DIAGNOSIS
• Isolation of Virus
• Amplification of Nucleic acid
• Routine Diagnosis with serology
Detection of IgM antibody provides a
specific and reliable means for early diagnosis
ELISA and Dot blotting methods are used
DR.T.V.RAO MD 27
TREATMENT
• Chikungunya fever is not a life threatening infection. Symptomatic treatment for mitigating pain and fever using anti-inflammatory drugs along with rest usually suffices. While recovery from Chikungunya is the expected outcome, convalescence can be prolonged (up to a year or more), and persistent joint pain may require analgesic (pain medication) and long-term anti-inflammatory therapy
DR.T.V.RAO MD 28
CDC GUIDELINES FOR MANAGEMENT OF
CHIKUNGUNYA
DR.T.V.RAO MD 29
• There is no vaccine or specific antiviral treatment
currently available for Chikungunya fever. Treatment is
symptomatic and can include rest, fluids, and
medicines to relieve symptoms of fever and aching
such as ibuprofen, naproxen, acetaminophen, or
paracetamol. Aspirin should be avoided. Infected
persons should be protected from further mosquito
exposure (staying indoors in areas with screens and/or
under a mosquito net) during the first few days of the
illness so they can not contribute to the transmission
cycle.
VACCINES FOR CHIKUNGUNYA
• An experimental – live attenuated vaccine ( TSI – GSD – 218 ) enveloped by passage of an isolate from Thailand in MRC – 5 cell.
• At present used in some laboratory workers who can be protected,
Vaccine produces neutralizing antibodies
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PREVENTIVE MEASURES
SEEKING PROTECTION FROM CHIKUNGUNYA
When staying in affected areas:
• Wear long-sleeved shirts and long trousers
• Use mosquito repellents, coils or other devices that will help fend off mosquitoes
• If possible, sleep under bed nets pre-treated with insecticides
• If possible, set the air-conditioning to a low temperature at night – mosquitoes do not like cold temperatures
• Pregnant women, children under 12 years old, and people with immune disorders or severe chronic illnesses should be given personalised advice
DR.T.V.RAO MD
HOW CHIKUNGUNYA CAN BE
PREVENTED
• There is neither Chikungunya virus vaccine nor drugs are available to cure the infection. Prevention, therefore, centres on avoiding mosquito bites. Eliminating mosquito breeding sites is another key prevention measure. To prevent mosquito bites, do the following:
• Use mosquito repellents on skin and clothing • When indoors, stay in well-screened areas. Use bed
nets if sleeping in areas that are not screened or air-conditioned.
• When working outdoors during day times, wear long-sleeved shirts and long pants to avoid mosquito bite.
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BREEDING PLACES OF AEDES MOSQUITOS
TRY TO ELIMINATE ….
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REDUCING THE SPREAD OF THE
VECTOR
• The vector lives in a number of different habitats
• The presence of water is of great importance for mosquitoes’ breeding as their eggs require water in order to develop into adult mosquitoes
DR.T.V.RAO MD
USE OF LARVICIDES
(i) Where the water cannot be removed but used for cattle or other purposes, Temephos can be used once a week at a dose of 1 ppm (parts per million).
(ii) Pyrethrum extract (0.1% ready-to-use emulsion) can be sprayed in rooms (not outside) to kill the adult mosquitoes hiding in the house.
DR.T.V.RAO MD 35
SEVERITY OF INDIAN EPIDEMIC
• Till 10 October 2006, 151 districts of eight states/provinces of India have been affected by Chikungunya fever. The affected states are Andhra Pradesh, Andaman & Nicobar Islands, Tamil Nadu, Karnataka, Maharashtra, Gujarat, Madhya Pradesh, Kerala and Delhi.
• More than 1.25 million cases have been reported from the country with 752,245 cases from Karnataka and 258,998 from Maharashtra provinces. In some areas attack rates have reached up to 45%.
DR.T.V.RAO MD 36
CURRENT RESEARCH ON
CHIKUNGUNYA
• Researchers at the Institute Pasteur have managed to retrace the origin and evolution of the Chikungunya virus in the Indian Ocean through complete sequencing of the genome of six viral strains isolated from patients from Reunion Island and the Seychelles, as well as through partial sequencing of the viral protein E1 from 127 patients from the Indian Ocean islands (Reunion, Madagascar, Seychelles, Mauritius, Mayotte). Their study, published in PLoS Medicine, opens up new research paths that should help to explain the magnitude of the epidemic and the occurrence of severe forms of the disease.
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