York County Medicine Winter 2019 - 20

YO R K C O M E D S O C . O R G

FEATURE:

Notes from the Field:

Zoonotic Mycobacterium bovis
Disease in Deer Hunters
- Michigan, 2002-2017
Weekly / September 20, 2019 / 68(37);807-808
Related Pages
James Sunstrum, MD1; Adenike Shoyinka, MD2; Laura E. Power,
MD2,3; Daniel Maxwell, DO4; Mary Grace Stobierski, DVM5; Kim
Signs, DVM5; Jennifer L. Sidge, DVM, PhD5; Daniel J. O'Brien,
DVM, PhD6; Suelee Robbe-Austerman, DVM, PhD7; Peter
Davidson, PhD5 (View author affiliations: https://www.cdc.gov/
mmwr/volumes/68/wr/mm6837a3.htm?s_cid=mm6837a3_e&deli
veryName=USCDC_921-DM9093#contribAff)

n May 2017, the Michigan Department of Health and Human
Services was notified of a case of pulmonary tuberculosis caused
by Mycobacterium bovis in a man aged 77 years. The patient
had rheumatoid arthritis and was taking 5 mg prednisone daily;
he had no history of travel to countries with endemic tuberculosis,
no known exposure to persons with tuberculosis, and no history of
consumption of unpasteurized milk. He resided in the northeastern
Lower Peninsula of Michigan, which has a low incidence of
human tuberculosis but does have an enzootic focus of M. bovis
in free-ranging deer (Odocoileus virginianus). The area includes a
four-county region where the majority of M. bovis-positive deer
in Michigan have been found (1). Statewide surveillance for M.
bovis via hunter-harvested deer head submission has been ongoing
since 1995 (1); in 2017, 1.4% of deer tested from this four-county
region were culture-positive for M. bovis , compared with 0.05%
of deer tested elsewhere in Michigan (2). The patient had regularly
hunted and field-dressed deer in the area during the past 20 years.
Two earlier hunting-related human infections with M. bovis were
reported in Michigan in 2002 and 2004. In each case, the patients
had signs and symptoms of active disease and required medical
treatment.

York County Medicine | WINTER 2019

Whole-genome sequencing of the patient's respiratory isolate
was performed at the National Veterinary Services Laboratories
in Ames, Iowa. The isolate was compared against an extensive
M. bovis library, including approximately 900 wildlife and cattle
isolates obtained since 1993 and human isolates from the state
health department. This 2017 isolate had accumulated one single
nucleotide polymorphism compared with a 2007 deer isolate
(Figure on opposite page), suggesting that the patient was exposed to
a circulating strain of M. bovis at some point through his hunting
activities and had reactivation of infection as pulmonary disease in
2017.
Whole-genome sequencing also was performed on archived
specimens from two hunting-related human M. bovis infections
diagnosed in 2002 (pulmonary) and 2004 (cutaneous) that were
epidemiologically and genotypically linked to deer (3). The 2002
human isolate had accumulated one single nucleotide polymorphism
since sharing an ancestral genotype isolated from several deer in
Alpena County, Michigan, as early as 1997; the 2004 human isolate
shared an identical genotype with a grossly lesioned deer harvested
by the patient in Alcona County, Michigan, confirming that his
infection resulted from a finger injury sustained during fielddressing. The 2002 and 2017 cases of pulmonary disease might
have occurred following those patients' inhalation of aerosols during
removal of diseased viscera while field-dressing deer carcasses (4).
In Michigan, deer serve as maintenance and reservoir hosts for
M. bovis, and transmission to other species has been documented (1). Since
1998, 73 infected cattle herds have been identified in Michigan
(5)
, resulting in increased testing and restricted movement of cattle
outside the four-county zone. Transmission to humans also occurs,
as demonstrated by the three cases described in this report; however,
the risk for transmission is understudied. Similar to Mycobacterium

http://www.YORKCOMEDSOC.ORG https://www.cdc.gov/mmwr/volumes/68/wr/mm6837a3.htm?s_cid=mm6837a3_e&deliveryName=USCDC_921-DM9093#contribAḀ)

York County Medicine Winter 2019

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