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Volume 8, Number 10—October 2002
Bioterrorism-related Anthrax

Anthrax Perspectives

Epidemiologic Responses to Anthrax Outbreaks: A Review of Field Investigations, 1950–2001

Michael E. Bales*, Andrew L. Dannenberg*Comments to Author , Philip S. Brachman†, Arnold F. Kaufmann*, Peter C. Klatsky*‡, and David A. Ashford*
Author affiliations: *Centers for Disease Control and Prevention, Atlanta, Georgia, USA; †Emory University Rollins School of Public Health, Atlanta, Georgia, USA; ‡Mt. Sinai School of Medicine, New York, New York;

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Table 2

Characteristics of CDC field investigations of anthrax in humans and animals, 1950–August 2001a

No. of cases
Reference Comments
  Human   Animal
Agricultural settings (n=24 investigations)
2001 TX (southwest) 1 1,638 Epi-Aid 2001-61 Large epizootic affecting 63 properties in five counties; members of at least 11 animal species were infected with Bacillus anthracis.
2000 ND (east) 1 Multiple Epi-Aid 2000-69, (14) USDA recommended quarantine on affected premises, vaccinating livestock on surrounding premises, and burning and/or burying infected carcasses, bedding, and other nearby materials.
1998 Kazakhstan At least 53 Multiple Epi-Aid 1998-83 Multivariate analysis found highest risk for cutaneous anthrax from slaughtering, butchering, and cutting B. anthracis–infected animals; eating cooked infected meat not an important risk factor.
1998 Uvalde, TX One vaccine exposure 0 Epi-Aid 1998-55 Patient accidentally exposed to attenuated live anthrax vaccine while vaccinating horse, experienced severe myalgia and fatigue, then began antibiotic prophylaxis and recovered. Laboratory tests negative for B. anthracis.
1993 ND (southeast) 0 8 (15) NIOSH and USDA investigation following major flooding, anthrax in livestock, and soil contamination. Concern over contaminated water supply, but all water samples negative.
1986 Paraguay At least 21 0 Epi-Aid 1986-39, (16) Community outbreak of cutaneous anthrax in a remote village.
1979 Clay County, IA 0 16 Epi-Aid 1979-95 Raising chlorine level to 2 ppm eliminated two positive samples in well water. In local hospital records, no difference in number of gastrointestinal symptoms compared with same month in previous year.
1976 Foard and Cottle Counties, TX 0 At least 160 Epi-Aid 1976-115, (17) Significantly higher attack rates in bulls and horses; evidence against flies as important vector.
1974 Falls County, TX 0 At least 236 Epi-Aid 1975-6, (18,19) B. anthracis– positive sample from city water tap, so city water supply was hyperchlorinated. Soil samples collected to document efficacy of carcass incineration were negative.
1971 Danville, PA 0 33 Epi-Aid 1972-19 B. anthracis isolated from both hay and soil samples.
1971 Gonzales, LA 2 588 Epi-Aid 1971-131, (3,20,21) One culture positive and one negative in exposed veterinarians. Low attack rate in calves reduced likelihood that biting flies were an important vector.
1970 Yoder, WY 0 8 Epi-Aid 1971-44, (22) Veterinarian placed on antibiotic prophylaxis as a result of laceration while performing necropsy.
1968 Inyo County, CA 1 176 Epi-Aid 1969-20, (23) Extensive discussion and literature review of Tabanid species (horsefly) as potential vector; role in transmission remains inconclusive.
1968 Hampton, CT 0 3 Epi-Aid 1968-78 204 kg of B. anthracis–contaminated meat sold as hamburger before investigation. No human cases of anthrax known to have occurred as a result.
1965 Grand Forks, ND 0 19 Epi-Aid 1966-12, (24) 30 diabetic children swam 3 miles downstream from where an animal was found dead from anthrax; riverborne spread determined minimal; prophylaxis considered unnecessary.
1962 MS 0 Multiple Epi-Aid 1963-2 Involved many counties.
1959 Brownsville, Cameron County, TX 5 125 Epi-Aid 1960-12 Two cases laboratory confirmed. Cases occurred in three veterinarians and two other patients who had intimate contact during necropsy, handling, or skinning.
1959 NJ (south) 1 2 cows, many hogs Epi-Aid 1959-38 Not laboratory confirmed. Several hogs developed illness after feeding on entrails of sick cows.
1958 LA (north) 0 15–20 Epi-Aid 1958-42 Involved cows, sheep, and horses.
1957 Vinita, OK 1 400–500 Epi-Aid 1958-11, (25) Large epizootic on farms curtailed after intensive immunization campaign.
1956 Saratoga, WY 0 Multiple Epi-Aid 1957-17 Animal anthrax in mountainous area led to concern over water supply downstream.
1956 MS (northwest) 0 >250 Epi-Aid 1957-3 No evidence to support insectborne transmission, despite local beliefs. Involved 224 head of cattle, 42 mules, 5 horses, 3 sheep, 2 goats, multiple hogs. One case of suspected anthrax in a child was investigated and determined to be mumps.
1955 LA (southeast) 0 1,404 Epi-Aid 1955-5 Large epizootic in cattle. Unconfirmed reports of four human cases. B. anthracis isolated from flies in two instances at State Animal Disease Laboratory.
1952 OH (five counties) 0 Multiple Epi-Aid 1952-13, (26) B. anthracis isolated from swine feed; contaminated bonemeal suspected as source of infections.
Textile mills (n=13 investigations)
1987 Charlotte, NC 1 0 Epi-Aid 1987-77, (27) Suspected cross-contamination of Australian wool from storage space shared with contaminated West Asian cashmere.
1978 NH (southeast) 2 0 Epi-Aid 1978-65 Patients did not wear protective equipment. One had systemic signs and symptoms (fever, headache, sore neck, malaise, anorexia) after his initial lesion was lanced. Subsequent full recovery.
1978 Shelby, NC 2 0 Epi-Aid 1978-47 Contents of vacuum cleaner bags or floor sweepings from four employee homes were collected; 1 tested positive for B. anthracis. 300 soil samples tested from mill premises, landfill site, and nearby residences. In mill, more positive samples in rooms where earliest processing occurred.
1974 Belton, SC 1 0 Epi-Aid 1974-77 Report suggested prevention should be based on minimizing contact between employees and contaminated material, and on routine vaccination of employees at risk. Patient not adequately vaccinated.
1972 Manchester, NH N/A N/A Epi-Aid 1972-94 Effectiveness of formaldehyde vapor decontamination of B. anthracis spores assessed using spore strips in treated and untreated (control) areas of mill complex, and comparing pre- and posttreatment surface samples. No positives among 599 posttreatment specimens.
1967 Dillon, SC N/A N/A (28) A building contaminated with B. anthracis was successfully decontaminated with formaldehyde vapor. 100,000 spores on 24 plates pretreatment were reduced to 21 sterile plates, and 3 plates with 2 colonies each, posttreatment. 26 of 142 surface swabs tested positive before decontamination, and 1 of 200 swabs tested positive 6 months after decontamination. Building was deemed safe for occupancy and no further cases were reported.
1966 Manchester, NH 2 0 Epi-Aid 1967-43 Patient with inhalational anthrax had history of "smoker's cough," diabetes, alcoholism, and chronic pancreatitis. Exposure believed to have occurred while patient worked for 4–5 hours directly opposite a goat hair–processing mill.
1961 Philadelphia, PA 1 0 Epi-Aid 1961-40; (29) After case reported, supplies of new and improved Wright vaccine sent to mill for use among employees.
1960 SC 4 0 Epi-Aid 1960-31, (30) All four cases responded well to antibiotic treatment.
1957 Philadelphia, PA 1 0 (31,32) Two additional inhalational cases mentioned that occurred over an 8-year period in persons living near the same contaminated tannery.
1957 Manchester, NH 9 0 Epi-Aid 1958-18, (3336) Employees noted increased dust in air after initiating a new scouring technique in textile mill.
1956 Monroe, NC >5 0 Epi-Aid 1956-29, (37) Studies indicated heavy environmental contamination of mill with B. anthracis spores.
1953 Monroe, NC 1 0 Epi-Aid 1953-14 Nasal swabs of employees performed to assess exposure. No results available.
Other settings (n=7 investigations)
1998 CA, IN, KY, TN 0 0 Epi-Aid 1999-25, (38) Evaluation of multiple telephone threats and letters alleged to contain B. anthracis. Report included recommendations for response to bioterrorism threats.
1976 Morro Bay, CA 1 0 (12,39,40) Suspected source of anthrax in home craftsman was contaminated yarn imported from Pakistan. Multiple samples of yarn tested positive for B. anthracis. Subsequent CPSC warning on imported yarn.
1975 Camden, NJ 3 0 (4143) Cutaneous anthrax in three gelatin manufacturing plant workers from contact with contaminated dry cattle bones; FDA recall of dicalcium phosphate animal feed product.
1974 Sequim, WA 0 42 (44,45) Several cougars and other large felines on private game farm died after feeding on infected horsemeat. Primary source: horse's saddle pad contained B. anthracis–contaminated goat hair from Afghanistan and Pakistan. Subsequent CPSC warning on contaminated saddle pads.
1974 Haiti; FL 1 in US; 194 in Haiti (1963-1974). 0 Epi-Aid 1974-96, (7,4650) One human case in U.S.; 194 cases identified in Haiti in 1963–1974. 72 (25%) of 287 Haitian goatskin handicrafts tested from January to May 1974 were culture positive for B. anthracis, including voodoo balancing dolls, rugs, whole skins, mosaic pictures, purses, and drums. Subsequent CPSC warning on contaminated Haitian goatskin products.
1966 Manchester, NH 1 0 Epi-Aid 1967-43-3 Source of cutaneous infection in housewife unknown, but knitting yarn could not be ruled out. Three samples from knitted sweater positive for B. anthracis; samples from other sources negative.
1964 Oxford, OH 1 0 (51,52) Fatal cutaneous anthrax in installer of pipe insulation made with imported goat hair. Insulation and goat hair samples tested positive for B. anthracis.
Suspected anthrax shown due to other causes (n=5 investigations)
1975 Yavapai County, AZ 1 0 Epi-Aid 1975-115 23-year-old male machinist initially thought to have anthrax but quickly determined to have plague.
1969 Casper, WY 1 0 Epi-Aid 1969-78 Meat packing company employee; anthrax thought not to be responsible.
1967 Nepal 26 Multiple Epi-Aid 1968-34 Community outbreak of cutaneous disease; subsequently diagnosed as plague.
1965 Charleston, SC 1 0 Epi-Aid 1966-18, (53) Cutaneous disease in customs inspector; B. anthracis not implicated.
1957 Jamestown, NY 5 0 Epi-Aid 1958-16 Cutaneous disease in butchers; later believed to be a streptococcal or staphylococcal infection.

aCDC, Centers for Disease Control and Prevention; CPSC, Consumer Product Safety Commission; OSHA, Occupational Safety and Health Administration; FDA, U.S. Food and Drug Administration; USDA, U.S. Department of Agriculture; NIOSH, National Institute for Occupational Safety and Health.

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