A Historical Look at Anthrax: Facts, Misperceptions, and the Importance of Diagnostics

LTC John M. Scherer, Ph.D., M.T. (ASCP) U.S. Army LTC John M. Scherer/(301) 619-8837/[email protected]

UNCLASSIFIED 1 March 2010

Anthrax vaccine trials begin Annals New York Acad Sci 1970; 174: 577-582 LTC John M. Scherer/(301) 619-8837/[email protected]

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Fact or Fiction

• • • • • Clinical Disease = Mortality Only particles < 5um in size are important Subclincal infections do not exist Inhalation Anthrax = Widened Mediastinum Diagnosis of anthrax is easy • Diagnostics only provide post-mortem confirmation LTC John M. Scherer/(301) 619-8837/[email protected]

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Agenda

• • • • Impact of particle size on infection Subclinical infections Inhalation anthrax cases from the Anthrax letters Diagnostics – – Why is it so hard?

Are there sufficient bacteria to detect?

• Temporal influence of antibiotic use on survival of inhalation anthrax • Conclusion LTC John M. Scherer/(301) 619-8837/[email protected]

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Particle Size Alters Infectious Dose

In NHPs 12 um particles are14X less effective than single cell particles LTC John M. Scherer/(301) 619-8837/[email protected]

UNCLASSIFIED J of Hyg 1953; 51 359-371 Slide 5 1 March 2010

Aerosolized Bacillus anthracis in Goat Hair Processing Mills

Am J Hyg 1960, Vol 72: 24-31 LTC John M. Scherer/(301) 619-8837/[email protected]

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Do Subclinical Infections Occur?

LTC John M. Scherer/(301) 619-8837/[email protected]

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The case against Subclinical Infection

• No increase in protection based on length of employment in hair processing mills (Anal New York Acad Sci 1958; 70: 574-583) – Does subclinical infection correlate with protection?

• No asymptomatic cases found following sero-surveys of potentially exposed individuals of anthrax letters (n=66) (Clinical Infectious Diseases 2005; 41:991 –7) – Antibiotic use?

LTC John M. Scherer/(301) 619-8837/[email protected]

UNCLASSIFIED Slide 8 1 March 2010

The case for Subclincal Infection

Albrink WS. Am J Path 1959; 35: 1055 1065 “The first two animals (John and Melvin) exhibited no positive physical disorder after their initial exposure and survived despite the fact that organisms were demonstrated in the blood of one on the second through the tenth days and of the other from the third through the eleventh days. The animals maintained their appetites and their vigorous protestations to physical examination in unabated manner. Although a bacteremia was apparent in each, it was of low grade and exhibited no progression. The temperature varied little from normal (100 to 101 F).” Norman, PS, Am J Hyg 1960; 72: 32-37.

LTC John M. Scherer/(301) 619-8837/[email protected]

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2001 Inhalation Anthrax Cases

LTC John M. Scherer/(301) 619-8837/[email protected]

UNCLASSIFIED 1 March 2010

Inhalation anthrax from Anthrax letters

• 11 people infected with

Bacillus anthracis

by aerosol route • 55% (6/11) of the inhalation anthrax cases survived • Average time from exposure to symptoms (when known) – 4.5 days (SD 0.8 days) • Average time of symptoms before treatment with antibiotics – 3.8 days (SD 1.6 days) • On average it was ~8 days from the initial exposure before therapy was initiated UNCLASSIFIED LTC John M. Scherer/(301) 619-8837/[email protected]

1 March 2010

Inhalation anthrax from Anthrax letters

• On average it was ~8 days from the initial exposure before therapy was initiated • Observations consistent with historical cases of inhalation anthrax • Only 7 of 11 (64%) had a widened mediastinum LTC John M. Scherer/(301) 619-8837/[email protected]

UNCLASSIFIED 1 March 2010

Technical Memorandum, Medical Aspects of Anthrax, AD 801-504, 1966 (date scanned) United States Army Biological Laboratories, Fort Detrick LTC John M. Scherer/(301) 619-8837/[email protected]

UNCLASSIFIED 1 March 2010

Inhalation anthrax from Anthrax letters

• On average it was ~8 days from the initial exposure before therapy was initiated • Observations consistent with historical cases of inhalation anthrax • Only 7 of 11 (64%) had a widened mediastinum • In the post 2001 sero-survey, ~10% (n=6/66) hade a widened mediastinum that was not attributed to

B. anthracis

exposure • 3 of the 11 individuals (27%) were sent home after seeking health care UNCLASSIFIED LTC John M. Scherer/(301) 619-8837/[email protected]

1 March 2010

Diagnostics

LTC John M. Scherer/(301) 619-8837/[email protected]

UNCLASSIFIED 1 March 2010

Why is Bacillus anthracis so difficult to diagnose?

• • Physician – – Uncommon Generic flu-like illness Laboratory – – Uncommon Culture contamination with

Bacillus species

is “common” – – Looks like other non-pathogenic

Bacillus species

Clinical labs reluctant to report contaminants LTC John M. Scherer/(301) 619-8837/[email protected]

UNCLASSIFIED 1 March 2010

Why is Bacillus anthracis so difficult for clinical labs to identify?

• Study conducted by Connecticut Depart of Public Health (EID 2005; 11: 1583-1486) • • • • • • 33 of 34 of Connecticut's clinical labs participated Mar to Dec 2003 (10 months) GPRs in blood or CSF isolated < 32hours 623 isolates reported (average 62/month) 195 of the isolates were

Bacillus species

(not anthracis) Additional workload ~0.3 FTEs LTC John M. Scherer/(301) 619-8837/[email protected]

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In animal models, is there sufficient bacteremia to detect?

• Some basic assumption that are supported: – – – Higher doses decrease incubation period There is bacteraemia when animals are symptomatic Levels vary but typically are > 1000 org/ml – Toxin levels are also detectable • However, it is extremely difficult to provide a precise number because the studies use different strains, doses, animal models, and methods for determining bacteremia LTC John M. Scherer/(301) 619-8837/[email protected]

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Sample data

Technical Memorandum 19, Pathogenesis of Anthrax- A Progress Report, November 1962 United States Army Biological Laboratories, Fort Detrick LTC John M. Scherer/(301) 619-8837/[email protected]

UNCLASSIFIED 1 March 2010

Clinical Cases

LTC John M. Scherer/(301) 619-8837/[email protected]

UNCLASSIFIED 1 March 2010

1958 Ft Detrick Case Reported as a minimum value Technical Memorandum 19, Pathogenesis of Anthrax- A Progress Report, November 1962 United States Army Biological Laboratories, Fort Detrick LTC John M. Scherer/(301) 619-8837/[email protected]

UNCLASSIFIED 1 March 2010

Inhalation anthrax from Anthrax letters

• Inhalation anthrax letter cases - All blood samples tested before administration of antibiotics were positive by PCR – Assay sensitivity 1 pg or 167 org (EID 2002; 8: 1178 1181).........1 org ~6 fg – – Sample volume 5 ul Equates to ~30,000 org/ml of eluate • – Specimen processing should “concentrate” sample by a factor of 10-100x • Therefore, predicted levels in the blood would be at a minimum between 300-3,000 org/ml Time-to-positive estimates for blood cultures supports an estimate of >1000 org/ml (ave 14.5hrs from collection, n=7) UNCLASSIFIED LTC John M. Scherer/(301) 619-8837/[email protected]

1 March 2010

Legend is incorrect in manuscript, should be ng/ml

Clinical Infectious Diseases 2007; 44:968 –71

LTC John M. Scherer/(301) 619-8837/[email protected]

UNCLASSIFIED 1 March 2010

Temporal influence of antibiotic use on survival of inhalation anthrax

LTC John M. Scherer/(301) 619-8837/[email protected]

UNCLASSIFIED 1 March 2010

Anthrax survival predictions

Wilkening, PNAS 2006;103: 7589 –7594 Holty, Ann Intern Med. 2006;144: 270-280 Note: Left graph X axis is day symptoms develop, right graph is day of exposure For left graph symptoms arise at a mean of 4 days following exposure LTC John M. Scherer/(301) 619-8837/[email protected]

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Conclusion

• • • • • Diagnosis of inhalation anthrax does not equal death (with appropriate therapy, individuals who are symptomatic for 4 days still have ~50% survival rate) • Initiating therapy each day before the onset of fulminate anthrax improves survival by ~10-20% Increasing the particle size increases the ID50, it does not render the material non-infective Widened-mediastinum is present in only approximately 50% of cases and has been observed in non-anthrax cases Individuals seeking medical care are predicted to have detectable levels bacteremia Anthrax toxins are readily detectable at the same time as bacteria appear in the blood UNCLASSIFIED LTC John M. Scherer/(301) 619-8837/[email protected]

1 March 2010

LTC John M. Scherer Ph.D., M.T. (ASCP) Voice: 301-619-8837 / DSN 343-8837 Email: [email protected]

LTC John M. Scherer/(301) 619-8837/[email protected]

UNCLASSIFIED 1 March 2010