on august 5 , 2011 , a community hospital laboratory contacted the minnesota department of health to submit for identification a bacillus sp .
cdc typed the isolate as gt59 using multiple - locus variable - number tandem repeat analysis specific for 8 loci ( 8) .
the isolate was related to strains with genotypes generally associated with imported animal products and most closely related to a strain obtained from a 1965 investigation of a case of cutaneous anthrax in a worker at a new jersey gelatin factory , which used bone imported from india ( 9,10 ) .
the patient , a 61-year - old florida resident , had begun a 3-week trip with his wife on july 11 , 2011 .
they drove through north dakota , montana , wyoming , and south dakota , where animal anthrax is sporadic or enzootic ( figure ) .
while traveling , they walked in national parks , collected loose rocks , and purchased elk antlers . on july 29 , they drove through herds of bison and burros , frequently stopping while animals surrounded their vehicle .
the man was hospitalized on august 2 , following onset of illness while he was en route to minnesota .
his condition was treated with antimicrobial drugs , according to published recommendations , supplemented with anthrax immune globulin , and he fully recovered ( 11 ) .
route traveled by anthrax case - patient in the united states , july 11 , 2011 to august 2 , 2011 .
the couple had no contact with dead animals , but reported dusty conditions while driving through the herds .
the patient had not traveled abroad during the past year or been exposed to tanneries , wool or goat hair mills , bone meal , african drums , or illicit drugs .
he crafted metal and stone jewelry and knives with elk - antler handles in a home workshop .
one month before illness onset , he had constructed fishing flies using hair from a healthy elk he hunted in kentucky 8 months previously . because his wife may have experienced the same exposure , postexposure prophylaxis was provided , including a 60-day course of oral antimicrobial drugs and a 3-dose series of anthrax vaccine adsorbed ( emergent biosolutions , lansing , mi , usa ) , under an investigational new drug protocol . symptoms of anthrax did not develop
; however , she was unable to provide blood for serologic testing before starting postexposure prophylaxis . environmental sampling of the entire trip route was not feasible because the travel route involved several thousand miles over 3 weeks , specific suspected exposure locations were lacking , and recovering b. anthracis from environmental samples ( 12 ) , particularly soil ( 13 ) , gives variable results and is inefficient . to identify an exposure source and focus the environmental investigation , investigators obtained targeted samples from the vehicle and personal items where spores were likely to be found . from the patient s vehicle and contents ,
47 environmental samples were collected , and 18 environmental samples were obtained from his home workshop and garage ( table ) , following procedures of the national institute for occupational safety and health and the environmental protection agency ( 14 ) .
all samples were processed and cultured by using cdc s laboratory response network culture and pcr methods at the minnesota department of health and the florida department of health .
multiple agencies , including cdc , state public and animal health departments of minnesota , north dakota , montana , wyoming , south dakota , and florida , and other federal and state partners , conducted enhanced retrospective surveillance to identify other possible human or animal anthrax cases during june 1august 31 , 2011 .
infection preventionists , medical examiners , and coroners were asked if they were aware of cases of unexplained death or fulminant illness potentially caused by anthrax .
the us department of agriculture veterinary services and wildlife services / animal and plant health inspection service , the southeastern cooperative wildlife disease study , the us geological survey national wildlife health center , the national park service , and state wildlife and veterinary agencies were asked to report unexplained animal die - offs and animal deaths consistent with anthrax . in addition
, 450 laboratory response network and 7 national animal health laboratory network laboratories in the participating states , the national veterinary services laboratories , and other veterinary and wildlife laboratories were asked to review records for non - hemolytic bacillus spp .
a single bovine case was reported in aurora county , south dakota , in august 2011 ; however , the isolate was determined to be of an unrelated genotype ( gt3 ) .
no other anthrax - associated die - offs in wildlife or domestic animals were identified , and no other suspected or confirmed human cases of anthrax were identified or reported during this period .
we did not find a specific exposure associated with anthrax infection for this case - patient and no other human or related animal cases .
the clinical isolate genotype and sequence closely matched several previous environmental sample isolates from north america , however , no epidemiologic links were identified .
the case - patient was exposed to airborne dust while traveling through areas where anthrax was enzootic ; however , testing of vehicle air filters in which the dust was concentrated was negative for b. anthracis .
nonetheless , the patient may have been exposed through contact with an unidentified contaminated item .
this investigation was limited by the poor sensitivity expected for soil sampling and lack of data to guide additional focused environmental sampling , precluding widespread random sample collection and testing along the route traveled .
it is unusual for inhalation anthrax case - patients to have no identified exposure source ( 5,9,15 ) .
inhalation of spore - contaminated soil has been suggested as a possible source of infection for bison in anthrax outbreaks in canada ( 16 ) . a heavy equipment operator acquired inhalation anthrax during a bison outbreak in canada , where he dragged carcasses to burial sites and was exposed to airborne dust during operations ( 2 ) .
chronic pulmonary disease or immunosuppression may increase a person s susceptibility to inhalation anthrax ( 9,15 ) .
this case - patient had a decades - long history of chemical pneumonitis , and although he reported no respiratory difficulties , perhaps his risk was increased .
he also had a history of mild diabetes ; diabetes has been observed in other anthrax patients ( 9 ) .
this report highlights the challenges of investigating cases of anthrax when no specific suspected source exists .
anthrax , either naturally - occurring or bioterrorism - related , is a major public health concern , and timely recognition is critical .
clinicians and public health professionals should be cognizant that naturally acquired anthrax can occur in the united states and take appropriate steps to rapidly diagnose and investigate such cases .
 inhalation anthrax occurred in a man who vacationed in 4 us states where anthrax is enzootic . despite an extensive multi - agency investigation , 
 the specific source was not detected , and no additional related human or animal cases were found . although rare , inhalation anthrax can occur naturally in the united states . 
The Study
Conclusions