Chikungunya Virus

Chikungunya Virus

PATHOGEN SAFETY DATA SHEET – INFECTIOUS SUBSTANCES

SECTION I – INFECTIOUS AGENT

NAME: Chikungunya virus

SYNONYM OR CROSS REFERENCE: CHIKV (1-6), CHIK (2, 7-9), and chikungunya fever (2, 10).

CHARACTERISTICS: A member of the Togaviridae family (4, 10, 11), and Alphavirus genus (10, 11), belonging to the Semliki Forest serological complex (1, 11). CHIKV is a spherical enveloped virion that measures 60 to 70 nm in diameter (1, 11), and contains a single-stranded, positive-sense RNA genome (11).

SECTION II – HAZARD INFORMATION

PATHOGENICITY/TOXICITY: Translated from the African dialect of Swahili or Makonde, chikungunya means, “that which bends up” (1, 2, 12), “what bends” (10), or “to walk bent over” (13), and refers to the effect of the incapacitating arthralgia experienced by patients with CHIKV fever (1). CHIKV infection has an abrupt onset, characterised by fever, and severe arthralgia (2, 13), which is seen in 70% of cases (1). The fever rises quickly, often reaching 39 to 40 °C and is accompanied by intermittent shaking chills (2). The arthralgias are polyarticular, migratory and predominantly affect the small joints of the hands, wrists, ankles, and feet (2). Cutaneous manifestations are typical with many patients presenting a flush over the face and trunk. This is usually followed by a maculopapular rash, involving most commonly the trunk, and limbs, but the face, palms and soles can also show lesions (2). Other symptoms of CHIKV include myalgia, nausea, vomiting, headaches, nasal discharge, conjunctivitis, retrobulbar pain, photophobia, and lymphadenopathy (10). Haemorrhagic manifestations (petechiae, purpura, bleeding gums, nosebleeds, haematemesis, and melena) (1) have been documented, but only in Asia (10). The average fatality rate is 0.4% (2.8% in children and 1.6% in elderly people) (10).

EPIDEMIOLOGY: CHIKV was first recognised in Tanzania (formerly Tanganyika) in 1953 during an epidemic of dengue-like illness (12). Between the 1960s and 1990s, the virus was isolated repeatedly from numerous countries in Central and Southern Africa, including Sudan, Uganda, Democratic Republic of Congo, the Central African Republic, Malawi, Zimbabwe, Kenya, and South Africa (3). CHIKV has also been isolated in Western African countries, including Senegal, Benin, the Republic of Guinea, Côte d’Ivoire and Nigeria (3).

In Southeast Asia, frequent outbreaks were reported from the 1960s through to 2003 in India, Malaysia, Indonesia, Cambodia, Vietnam, Myanmar, Pakistan, and Thailand (3). Indeed, numerous cities, including Bangkok and Calcutta have been identified as particularly active sites of transmission and disease (3).

Beginning in 1986, CHIKV outbreaks resurged with major clusters documented in Senegal (1986, 1996, and 1997), Côte d’Ivoire (1996 and1997), Democratic Republic of Congo (1998-2000), Indonesia (2003), Kenya (2004), Comoros (2005), the Seychelles, Mauritius, Madagascar and Réunion islands (2005-2006), and India (2006 and 2007) (3).

Cases have also been reported in Europe (United Kingdom, Belgium, Germany, Czech Republic, Norway, Italy, Spain and France), Hong Kong, Canada, Taiwan, Sri Lanka and United States; however, these were directly associated with the return of tourists from India and the affected islands of the Indian Ocean (3, 13).

At Present, CHIKV is endemic in 23 countries and phylogenetic analysis of viral sequences has identified 3 distinct clades: West African, Central/East African and Asian (3, 7).

There are 2 epidemiological transmission cycles of CHIK fever: a sylvatic cycle, occurring primarily in Africa mainly between wild primates and arboreal Aedes mosquitoes (2, 3), where humans are accidental hosts; and an urban human-mosquito-human transmission cycle that typically occurs in cities in Asia (2).

HOST RANGE: Humans (1-3, 6, 7, 10, 11, 13), non-human primates, rodents, and birds (11, 13).

INFECTIOUS DOSE: Unknown.

MODE OF TRANSMISSION: CHIKV is transmitted to humans from infected non-human primates and other humans by the bite of Aedes mosquitoes (1). Evidence exists that CHIKV can also be passed from an infected mother to a developing foetus (2, 13). Furthermore, inhalation of aerosolised CHIKV in a laboratory setting may lead to CHIKV infection (14).

INCUBATION PERIOD: Usually 2 to 3 days (1, 2), with a range of 1 to 10 days (2, 10, 12).

COMMUNICABIILTY: Person-to-person transmission is only thought to occur in utero between a mother and her foetus (2).

SECTION III – DISSEMINATION

RESERVOIR: Humans serve as the reservoir for CHIKV during epidemic periods (2, 11, 13). Outside these periods the main reservoirs are monkeys (10, 11, 13), rodents (10, 13), bats (10), and birds (10, 11, 13).

ZOONOSIS: Yes, indirectly from mosquitoes infected by non-human reservoir hosts (sylvatic cycle transmission) (2, 3).

VECTORS: Mosquitoes (1-3, 7, 10, 11, 13). In Asia and the Indian Ocean region, the main vectors are Aedes aegypti (2, 10, 11) and Aedes albopictus (2, 11). A larger range of Aedes species transmit CHIKV in Africa, including Aedes furcifer (2, 10, 11), Aedes taylori (2), Aedes vittatus, Aedes fulgens (11), Aedes luteocephalus (2, 11), Aedes dalzieli, Aedes vigilax, Aedes camptorhynchites (11), Aedes africanus (2, 10), and Aedes neoafricanus (2).

SECTION IV – STABILITY AND VIABILITY

DRUG SUSCEPTIBILITY: No antivirals are currently available. Under experimental conditions, interferon-α2b, glycyrrhizin, 6-azauridine and ribavirin have all been shown to reduce CHIKV virus yield in a concentration dependent manner in vitro (4). Moreover there is a synergistic efficacy between interferon-α and ribavirin against CHIKV in vitro (4).

SUSCEPTIBILITY TO DISINFECTANTS: No information specific to CHIKV; however, most lipid enveloped viruses are sensitive to 70% (v/v) ethanol, sodium hypochlorite, formaldehyde, glutaraldehyde, phenolics, iodophors, and quaternary ammonium compounds (15).

PHYSICAL INACTIVATION: Inactivated by desiccation and temperatures above 58°C (11).

SURVIVAL OUTSIDE HOST: Unknown.

SECTION V – FIRST AID / MEDICAL

SURVEILLANCE: Monitor for symptoms (2). Confirmation is via detection of CHIKV in blood samples via ELISA (6), RT-PCR (16), real time RT-PCR (5), indirect immunofluorescence (6), viral culture (2, 11), neutralization assays (2, 17), and/or haemagglutinin inhibition assays (2).

Note: All diagnostic methods are not necessarily available in all countries.

FIRST AID/TREATMENT: Treatments available are for symptoms only and include antipyretic (1) and anti-inflammatory drugs (1, 11) such as diclofenac (10). The use of steroids and aspirin should be avoided (10, 11). Movement and mild exercise tend to improve stiffness in the joints (2).

IMMUNIZATION: A commercial vaccine does not exist (2, 10), although some candidate vaccines have been tested on monkeys (8) and humans (phase II) (9), and a phase III trial of a candidate vaccine is in preparation (11).

PROPHYLAXIS: The only form of prophylaxis available is to minimise the risk of being bitten by infected mosquitoes by using mosquito nets and/or mosquito repellents (1, 10).

SECTION VI – LABORATORY HAZARDS

LABORATORY-ACQUIRED INFECTIONS: Forty-one cases were reported up until 1980 (14). Two more cases were reported in 1981 (17).

SOURCES/SPECIMENS: Blood (1, 2).

PRIMARY HAZARDS: Inhalation of CHIKV containing aerosols (14).

SPECIAL HAZARDS: Exposure to infected insects whilst performing CHIKV isolations in endemic areas (17).

SECTION VII – EXPOSURE CONTROLS / PERSONAL PROTECTION

RISK GROUP CLASSIFICATION: Risk Group 3(18).

CONTAINMENT REQUIREMENTS: Containment Level 3 facilities, equipment, and operational practices for work involving infectious or potentially infectious material.

PROTECTIVE CLOTHING: Personnel entering the laboratory should remove street clothing and jewellery, and change into dedicated laboratory clothing and shoes, or don full coverage protective clothing (i.e., completely covering all street clothing). Additional protection may be worn over laboratory clothing when infectious materials are directly handled, such as solid-front gowns with tight fitting wrists, gloves, and respiratory protection. Eye protection must be used where there is a known or potential risk of exposure to splashes (19).

OTHER PRECAUTIONS: All activities with infectious material should be conducted in a biological safety cabinet (BSC) or other appropriate primary containment device in combination with personal protective equipment. Centrifugation of infected materials must be carried out in closed containers placed in sealed safety cups, or in rotors that are unloaded in a biological safety cabinet (19). The use of needles, syringes, and other sharp objects should be strictly limited. Open wounds, cuts, scratches, and grazes should be covered with waterproof dressings. Additional precautions should be considered with work involving animals or large scale activities.

SECTION VIII – HANDLING AND STORAGE

SPILLS: Allow aerosols to settle and, while wearing protective clothing, gently cover the spill with paper towels and apply suitable disinfectant, starting at the perimeter, working inwards towards the centre. Allow sufficient contact time before clean up (19).

DISPOSAL: Decontaminate all materials for disposal by steam sterilisation, chemical disinfection, and/or incineration (19).

STORAGE: In sealed, leak-proof containers that are appropriately labelled and locked in a Containment Level 3 laboratory (19).

SECTION IX – REGULATORY AND OTHER INFORMATION

REGULATORY INFORMATION: The import, transport, and use of pathogens in Canada is regulated under many regulatory bodies, including the Public Health Agency of Canada, Health Canada, Canadian Food Inspection Agency, Environment Canada, and Transport Canada. Users are responsible for ensuring they are compliant with all relevant acts, regulations, guidelines, and standards.

UPDATED: August 2010.

PREPARED BY: Pathogen Regulation Directorate, Public Health Agency of Canada.

Although the information, opinions and recommendations contained in this Pathogen Safety Data Sheet are compiled from sources believed to be reliable, we accept no responsibility for the accuracy, sufficiency, or reliability or for any loss or injury resulting from the use of the information. Newly discovered hazards are frequent and this information may not be completely up to date.

Copyright © Health Canada, 2001

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