Bacillus anthracis

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Bacillus anthracis - Anthrax

Hosts

This bacterium infects multiple types of hosts including herbivorous mammals such as livestock and is considered zoonotic however humans are a dead end host and do not become infectious.

Transmission/Exposure Routes

Cutaneous: skin contact with spores from infected animals.
Gastrointestinal: eating poorly cooked meat/dairy from infected animal.
Inhalation: Inhalation of spores

Case fatality ratio

Case fatality ratios
Case Fatality Ratio Pathway/conditions Population References
1% Cutaneous with treatment General US Population (CDC)
20% Cutaneous without treatment General US population (CDC)
75% Inhalation despite treatment (CDC)
45% 2001 US Attack Adult US (Holty et al, 2006)
14% (5 of 37) Cutaneous Children 1900-2005 (Bravata et al, 2007)
60% Inhalation Children 1900-2005 (Bravata et al, 2007)
65% (13 of 20) Gastrointestinal Children 1900-2005 (Bravata et al, 2007)
100% (6 of 6) primary meningoencephalitis Children 1900-2005 (Bravata et al, 2007)
1.5% (of 132) Not reported Hospitalized adults and children, Turkey 1986 to 2000 (Kaya et al, 2002)

Incubation Times

Incubation Times
Days Pathway Population Reference
0-1 Cutaneous (CDC)
1-7 days Inhalation

Ingestion

(CDC)
60 (max) Inhalation

Ingestion

(CDC)
10 Days (SD: 8.67) Inhalation Sverdlovsk 1979 outbreak (70 cases) (Brookmeyer et al, 2005)

Burden of Disease

Duration of infectiousness and disease

Anthrax is not contagious and cannot be transmitted from person-to-person.

Symptomology

Flu-like symptoms including: Fever (temperature greater than 100 degrees F). The fever may be accompanied by chills or night sweats. Cough, usually a non-productive cough, chest discomfort, shortness of breath, fatigue, muscle aches Sore throat, followed by difficulty swallowing, enlarged lymph nodes, headache, nausea, loss of appetite, abdominal distress, vomiting, or diarrhea

Excretion Rates (see Exposure)

Immunity

Anthrax vaccination consists of 5 total intramuscular injections, followed by recommended annual boosters to maintain immunity.

Microbiology

Gram +, aerobic, encapsulated, nonmotile, spore-forming, rod-shaped bacterium. Extremely hardy spores can persist for years, even decades.

Envrionmental Survival

Recommended Dose Response model

Dose response models for Bacillus anthracis

Exponential model: optimal value of k is 1.65E-05
Exponential model.png



References

CDC Anthrax Page
http://en.wikipedia.org/wiki/Anthrax
Holty J, Bravata D, Liu H, Olshen R, Mcdonald K, and Owens D. (2006) Systematic Review: A Century of Inhalational Anthrax Cases from 1900 to 2005. Annals of Internal Medicine. 144, 4. 270-280. Full Text
Bravata D, Holty J, Wang E, Lewis R, Wise P, McDonald K, and Owen D. (2007) Inhalational, Gastrointestinal, and Cutaneous Anthrax in Children. Arch Pediatr Adolesc Med. 161 (9): 896-905. Full Text
Kaya A, Tasyaran M, Erol S, Ozkurt Z, and Ozkan B. (2002) Anthrax in Adults and Children: A Review of 132 Cases in Turkey. Eur J Clin Microbiol Infect Dis. 21: 258-261. Full Text
Brookmeyer, R., Johnson, E., & Barry, S. (2005). Modelling the incubation period of anthrax. Statistics in Medicine, 24(4), 531–542. doi:10.1002/sim. [http://onlinelibrary.wiley.com.proxy1.cl.msu.edu/doi/10.1002/sim.2033/pdf}}