Mucambo virus: Infectious substances pathogen safety data sheet

Section I – Infectious agent

Name

Mucambo virus

Agent type

Virus

Taxonomy

Family

Togaviridae

Genus

Alphavirus

Species

Mucambo virus

Synonym or cross-reference

Also known as Venezuelan equine encephalitis (VEE) virus subtype IIIA ^Footnote 1 and previously referred to as a strain of VEE virus ^Footnote 2.

Characteristics

Brief description

Mucambo virus (MUCV) is a member of the Venezuelan equine encephalitis (VEE) complex of viruses^Footnote 1. MUCV is an arbovirus that can cause self-limiting febrile illness in humans and is considered to be an enzootic VEE complex virus^{Footnote 3Footnote 4}.

Properties

MUCV is a spherical, enveloped virus measuring 65-70 nm in diameter^Footnote 1. The nucleocapsid core contains a single-stranded positive-sense RNA genome approximately 11.4 kb in length.^{Footnote 1Footnote 5}.

Section II – Hazard identification

Pathogenicity and toxicity

MUCV causes subclinical infection or self-limiting febrile illness in humans, indicating that MUCV exhibits reduced virulence in humans relative to closely phylogenetically related viral species of the VEE complex.^{Footnote 3Footnote 6Footnote 7}. Symptoms include fever, headache, and malaise lasting 2 to 3 days^Footnote 3. No MUCV-associated human fatalities have been reported.

In natural settings, enzootic strains of the VEE complex, including MUCV, are generally avirulent for horses^Footnote 4; however, horses experimentally inoculated with MUCV developed febrile illness and viremia^Footnote 2. Macaques experimentally infected with MUCV via the aerosol route developed fever and clinical signs of mild encephalitis, including loss of balance and muscle control^Footnote 8. The viremic period was short, lasting about 2 days^Footnote 8. Symptoms resolved after approximately 10 days and all macaques fully recovered^Footnote 8.

Epidemiology

MUCV has been found in several restricted geographic foci within South America, including parts of Brazil^{Footnote 9Footnote 10}, Trinidad^Footnote 11, Suriname^Footnote 7, and Peru^{Footnote 12Footnote 13}. MUCV disease incidence in humans is sporadic, with only seven MUCV isolates recovered from humans prior to 1992^Footnote 3. In MUCV-endemic areas in the Brazilian Amazon, prevalence of MUCV antibodies in humans ranges from 0% to 34% (average 6%)^Footnote 6. MUCV is generally avirulent for equines^{Footnote 4Footnote 14}.

Host range

Natural host(s)

MUCV has been isolated from humans^Footnote 3, non-human primates^Footnote 15, and rodents^{Footnote 9Footnote 10}. Serological evidence indicates that horses^Footnote 16, opossums^Footnote 9, wild birds^Footnote 10, and bats^Footnote 17 are occasionally infected in regions where MUCV is prevalent.

Other host(s)

Experimental hosts include hamsters^Footnote 18 and guinea pigs^{Footnote 4Footnote 14}.

Infectious dose

Unknown.

Incubation period

The incubation period for VEE complex viruses in humans is approximately 2 to 5 days^Footnote 4. The incubation period for non-human primates infected with MUCV via the aerosol route is approximately 3 days^Footnote 8.

Communicability

In natural settings, MUCV is primarily transmitted to humans and other mammals via bites from infected mosquitoes^Footnote 9. In laboratory settings, MUCV is highly infectious via the aerosol route^{Footnote 19Footnote 20} and infection may occur through direct contact of virus with damaged skin or mucous membranes^{Footnote 21Footnote 22}.

Section III – Dissemination

Reservoir

MUCV is maintained in a transmission cycle involving mosquitoes and rodents^{Footnote 11Footnote 12Footnote 23}. Rodents including Oryzomys capito^Footnote 6, Oecomys spp.^Footnote 9, and Proechimys spp.^Footnote 9 have been implicated in MUCV transmission in the Amazon region.

Zoonosis

There is no evidence of MUCV transmission between humans and non-arthropod animals.

Vectors

Mosquitoes, primarily Culex (Melanoconion) portesi, become carriers of MUCV when they feed on viremic MUCV-infected hosts^{Footnote 6Footnote 11Footnote 24}.

Section IV – Stability and viability

Drug susceptibility/resistance

There are no approved drugs to treat illnesses caused by MUCV or other VEE complex viruses. Sorafenib, an FDA-approved drug used to treat carcinoma, inhibited replication of VEE complex viruses in vitro^Footnote 25. Pyrimethamine, an anti-malarial drug, and Prest-392 (Ketanserin tartrate hydrate) showed antiviral activity against VEE virus in vitro^Footnote 26.

Susceptibility to disinfectants

Ethanol (60-80%)^{Footnote 27Footnote 28}, quaternary ammonium compounds^{Footnote 28Footnote 29}, peracetic acid^Footnote 30, sodium hydroxide (100-500 mM)^Footnote 31, glutaraldehyde (0.1%)^Footnote 32, and free chlorine (1 ppm)^Footnote 33 are effective against MUCV.

Physical inactivation

Togaviruses are inactivated by UV irradiation^{Footnote 31Footnote 32} and heat treatment at 65 °C for 15 minutes^{Footnote 31Footnote 34}

Survival outside host

Alphaviruses are highly stable over a wide range of relative humidities (18 to 90%) and temperatures (-40 to 24 °C) in aerosol form^Footnote 35. Alphaviruses are also stable on dry surfaces. In darkness, the viral load on a glass surface decreased by 90% after approximately 4 days^Footnote 36.

Section V – First aid/medical

Surveillance

Illness caused by MUCV is clinically indistinguishable from other febrile illnesses such as dengue fever^Footnote 23. MUCV can be detected in tissue samples and in blood during the viremic phase of illness using reverse transcription polymerase chain reaction (RT-PCR) and sequencing^Footnote 37. Serological tests including plaque reduction neutralization assay, enzyme-linked immunosorbent assay (ELISA), hemagglutination inhibition, and complement fixation have been used in the diagnosis of illnesses caused by alphaviruses^Footnote 38. RT-PCR followed by electrospray ionization mass spectrometry has also been used to detect MUCV in mosquito samples^Footnote 13.

Note: The specific recommendations for surveillance in the laboratory should come from the medical surveillance program, which is based on a local risk assessment of the pathogens and activities being undertaken, as well as an overarching risk assessment of the biosafety program as a whole. More information on medical surveillance is available in the Canadian Biosafety Handbook (CBH).

First aid/treatment

Illness caused by MUCV is usually mild and self-limiting^Footnote 6. Treatment is mainly supportive to manage symptoms.

Note: The specific recommendations for first aid/treatment in the laboratory should come from the post-exposure response plan, which is developed as part of the medical surveillance program. More information on the post-exposure response plan can be found in the CBH.

Immunization

There are currently no licenced vaccines for VEE complex viruses, including MUCV. Alphavirus vaccine research has identified promising candidates^Footnote 20. Investigational vaccine products (e.g., live-attenuated TC-83 strain) have been administered to at-risk personnel working with VEE complex viruses^{Footnote 21Footnote 39}.

Note: More information on the medical surveillance program can be found in the CBH, and by consulting the Canadian Immunization Guide.

Prophylaxis

None.

Note: More information on prophylaxis as part of the medical surveillance program can be found in the CBH.

Section VI – Laboratory hazard

Laboratory-acquired infections

Prior to 1970, two laboratory workers developed febrile illness caused by MUCV^Footnote 19. The likely route of exposure was inhalation of infectious aerosols^Footnote 19.

Note: Please consult the Canadian Biosafety Standard (CBS) and CBH for additional details on requirements for reporting exposure incidents. A Canadian biosafety guideline describing notification and reporting procedures is also available.

Sources/specimens

Blood, cerebrospinal fluid, brain tissue, throat washings^{Footnote 8Footnote 12}.

Primary hazards

Inhalation of aerosolized infectious material, bite of an infected animal/arthropod, exposure of mucous membranes or broken skin to infectious material, and parenteral inoculation are primary exposure hazards for MUCV^Footnote 21.

Special hazards

None.

Section VII – Exposure controls/personal protection

Risk group classification

MUCV is a Risk Group (RG) 3 human pathogen and Risk Group 1 animal pathogen^{Footnote 40Footnote 41}.

Containment requirements

Containment Level 3 facilities, equipment, and operational practices outlined in the CBS for work involving infectious or potentially infectious materials, animals, or cultures.

Protective clothing

The applicable Containment Level 3 requirements for personal protective equipment and clothing outlined in the CBS to be followed. At minimum, use of full body coverage dedicated protective clothing, dedicated protective footwear and/or additional protective footwear, gloves when handling infectious materials or animals, face protection when there is a known or potential risk of exposure to splashes or flying objects, respirators when there is a risk of exposure to infectious aerosols, and an additional layer of protective clothing prior to work with infectious materials or animals.

Note: A local risk assessment will identify the appropriate hand, foot, head, body, eye/face, and respiratory protection, and the personal protective equipment requirements for the containment zone must be documented.

Other precautions

All activities involving open vessels of pathogens are to be performed in a certified biological safety cabinet (BSC) or other appropriate primary containment device. The use of needles, syringes, and other sharp objects to be strictly limited. Additional precautions must be considered with work involving animals or large scale activities.

Section VIII – Handling and storage

Spills

Allow aerosols to settle. Wearing protective clothing, gently cover the spill with absorbent paper towel and apply suitable disinfectant, starting at the perimeter and working towards the centre. Allow sufficient contact time before clean up (CBH).

Disposal

Regulated materials, as well as all items and waste to be decontaminated at the containment barrier prior to removal from the containment zone, animal room, animal cubicle, or post mortem room. This can be achieved by using decontamination technologies and processes that have been demonstrated to be effective against the infectious material, such as chemical disinfectants, autoclaving, irradiation, incineration, an effluent treatment system, or gaseous decontamination (CBH).

Storage

Containment Level 2, CL3, prions: The applicable Containment Level 3 requirements for storage outlined in the CBS are to be followed. Primary containers of regulated materials removed from the containment zone to be stored in a labelled, leak-proof, impact-resistant secondary container, and kept either in locked storage equipment or within an area with limited access.

SSBA: Containers of security sensitive biological agents (SSBA) stored outside the containment zone must be labelled, leakproof, impact resistant, and kept in locked storage equipment that is fixed in place (i.e., non-movable) and within an area with limited access.

An inventory of RG3 and RG4 pathogens, and SSBA toxins in long-term storage, to be maintained and to include:

• specific identification of the regulated materials
• a mechanism that allows for the detection of a missing or stolen sample in a timely manner

Section IX – Regulatory and other information

Canadian regulatory information

Controlled activities with MUCV require a Human Pathogens and Toxins Licence , issued by the Public Health Agency of Canada.

The following is a non-exhaustive list of applicable designations, regulations, or legislations:

• Human Pathogen and Toxins Act and Human Pathogens and Toxins Regulations
• Transportation of Dangerous Goods Regulations

Last file update

2020

Prepared by

Centre for Biosecurity, Public Health Agency of Canada.

Disclaimer

The scientific information, opinions, and recommendations contained in this Pathogen Safety Data Sheet have been developed based on or compiled from trusted sources available at the time of publication. Newly discovered hazards are frequent and this information may not be completely up to date. The Government of Canada accepts no responsibility for the accuracy, sufficiency, or reliability or for any loss or injury resulting from the use of the information.

Persons in Canada are responsible for complying with the relevant laws, including regulations, guidelines and standards applicable to the import, transport, and use of pathogens in Canada set by relevant regulatory authorities, including the Public Health Agency of Canada, Health Canada, Canadian Food Inspection Agency, Environment and Climate Change Canada, and Transport Canada. The risk classification and related regulatory requirements referenced in this Pathogen Safety Data Sheet, such as those found in the Canadian Biosafety Standard, may be incomplete and are specific to the Canadian context. Other jurisdictions will have their own requirements.

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