Pathogen Safety Data Sheets: Infectious Substances – Rickettsia akari

Section I - Infectious Agent

Name

Rickettsia akari

Synonym or Cross Reference

Rickettsialpox, vesicular rickettsiosis.

Characteristics

R. akari is a member of the family Rickettsiaceae. It is an obligate intracellular gram-negative coccobacillus and has a pleomorphic life cycle^{Footnote 1}. The bacterium is approximately 0.3 – 0.5 μm by 9 μm, has a transverse septum between two bacilli, and reproduces by binary fission ^{Footnote 2, Footnote 3}.

Section II - Hazard Identification

Pathogenicity / Toxicity

R. akari is the agent of rickettsialpox, which is a mild self-limited zoonotic febrile illness of the spotted fever group ^{Footnote 4}. Infection is characterized by, in 80% of cases, the appearance of a 0.5 – 1.5 cm eschar or painful lymph nodes associated with lymphadenopathy at the site of the infectious mite bite ^{Footnote 5, Footnote 6}. About 3-7 days after the skin lesion develops, the patient develops fever, headache and other systemic symptoms. Approximately 2-3 days later, a papulovesicular rash erupts on the trunk and extremities, which may be confused with chickenpox. Symptoms may later develop into organ-specific afflictions such as nausea, vomiting, and abdominal pain ^{Footnote 7}. No deaths have been reported from R. akari infections ^{Footnote 8}.

Epidemiology

Worldwide distribution – the bacteria have been found most commonly in urban areas of eastern United States, Turkey, Croatia, Ukraine, Russia, Mexico, Africa, and areas of Europe and Asia^{Footnote 5Footnote 9Footnote 10}. The first and only large epidemic occurred in 1946 in the Queens borough of New York City, and a causal agent was delineated shortly thereafter^{Footnote 9}. In total, approximately 800 cases of rickettsialpox have been reported; most of them having occurred between 1940–1950, and none has resulted in death^{Footnote 8}. Very few cases have been reported in the past 30 years.

Host Range

Humans, house-mice, domestic rats and Ukraine Rattus norvegicus, dogs, Korean reed voles, and other rodents ^{Footnote 4, Footnote 5Footnote 9Footnote 10}.

Infectious Dose

Unknown.

Mode of Transmission

R. akari can be transmitted via the bite of the house-mouse mite, or sometimes by transovarial transmission between insects ^{Footnote 1Footnote 5}.

Incubation Period

The typical incubation period is 12-15 days, but can be up to 28 days ^{Footnote 1}.

Communicability

Cannot be directly transmitted between humans.

Section III - Dissemination

Reservoir

R. akari is maintained in nature by mites carried by the house-mouse (Mus musculus) and domestic rats. Humans and other mammals can be accidental reservoirs ^{Footnote 4}.

Zoonosis

Yes. The bacteria can be transferred from animals to humans by mites ^{Footnote 5}.

Vectors

Rodent mites (Liponyssoides sanguineus) and possibly ticks as an accidental vector (Rhiphicephalus sanguineus), and has been confirmed in arthropods ^{Footnote 4Footnote 5}.

Section IV - Stability and Viability

Drug Susceptibility

Susceptible to tetracycline, and oral doxycycline for mild cases. Chloramphenicol can also be used as an alternative ^{Footnote 1}.

Drug Resistance

R. akari has not been found to be drug-resistant ^{Footnote 11}. The most effective antibiotic used to treat rickettsial infections is doxycycline.

Susceptibility to Disinfectants

Susceptible to 1% sodium hypochlorite, formaldehyde, ethanol, 2% glutaraldehyde ^{Footnote 12}.

Physical Inactivation

R. akari cells can be quickly inactivated at 56°C ^{Footnote 13}.

Survival Outside Host

Rickettsia species can only grow in living host cells (cell cultures or embryonated eggs) and do not survive well in the environment. The bacteria are unstable outside of the host and quickly lose their infectivity, as the bacteria are metabolically inactive outside of a host cell ^{Footnote 2}.

Section V – First Aid / Medical

Surveillance

Monitor for characteristic symptoms of infection, and for formation of an eschar at site of bite. Serological techniques such as indirect immunofluorescence antibody test (IFA) and enzyme-linked immunosorbent assays (ELISAs), and polymerase chain reaction techniques can also be used to diagnose R. akari infection ^{Footnote 1Footnote 8Footnote 9}.

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

First Aid / Treatment

Administer appropriate antibiotic treatment. Doxycycline is the treatment of choice for all rickettsial infections ^{Footnote 14}. Supportive therapy for the patient is important, with attention to fluid and electrolyte balance and maintenance of proper renal function.

Immunization

No vaccines are currently available for R. akari (or any rickettsial species) ^{Footnote 1}.

Prophylaxis

None. Measures in commercial rodent-control can be effective ^{Footnote 8}.

Section VI - Laboratory Hazards

Laboratory - Acquired Infections

4 cases of rickettsialpox occurred in laboratory workers shortly after an outbreak in 1946 ^{Footnote 15}. Other cases include infections in a rickettsiologist who worked with the pathogen, and in a technician who was believed to have been exposed through the respiratory or conjunctival mucous membranes during work with chicken yolk sacs infected with R. akari ^{Footnote 10}.

Sources / Specimens

Blood and serum samples of infected mammals ^{Footnote 4}.

Primary Hazards

Accidental parenteral inoculation, exposure to infective mites, inhalation of aerosols ^{Footnote 5Footnote 7Footnote 8}.

Special Hazards

None.

Section VII – Exposure Controls / Personal Protection

Risk Group Classification

Risk Group 2 ^{Footnote 16}.

Containment Requirements

Containment Level 2 facilities, equipment, and operational practices for work involving infectious or potentially infectious materials, animals, or cultures ^{Footnote 17}.

Protective Clothing

Lab coat. Gloves when direct skin contact with infected materials or animals is unavoidable^{Footnote 17}. Eye protection must be used where there is a known or potential risk of exposure to splashes.

Other Precautions

All procedures that may produce aerosols, or involve high concentrations or large volumes should be conducted in a biological safety cabinet (BSC)^{Footnote 17}. The use of needles, syringes, and other sharp objects should be strictly limited. Additional precautions should be considered with work involving animals or large scale activities.

Section VIII – Handling and Storage

Spills

Allow aerosols to settle and, wearing protective clothing, gently cover spill with paper towels and apply an appropriate disinfectant, starting at the perimeter and working towards the centre. Allow sufficient contact time before clean up.

Disposal

Decontaminate all wastes that contain or have come in contact with the infectious organism before disposing by autoclave, chemical disinfection, gamma irradiation, or incineration.

Storage

The infectious agent should be stored in leak-proof containers that are appropriately labelled. R. akari cells are best preserved by rapid freezing and storage below –50˚C ^{Footnote 13}.

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

February, 2018

Prepared by

Centre for Biosecurity, 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 ©
Public Health Agency of Canada, 2018
Canada

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