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	va1-sg19016.securesites.net

	version=3.1.8





SALMONELLOSIS, SEROTYPE ENTERITIDIS, LAB WORKERS - USA (MAINE)

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On 15 Nov 2006, the Maine Department of Health and Human Services 

(MDHHS) was notified of a case of salmonellosis (a nationally 

notifiable disease) in an employee of a facility that produced 

poultry vaccine. When a 2nd case of salmonellosis in another employee 

at the same facility was reported on 25 Nov 2007, MDHHS began an 

outbreak investigation. Results of that investigation suggested that 

21 employees of the facility became ill during a 1 month period from 

exposure to a strain of _Salmonella [enterica_] serotype Enteritidis 

that was used in vaccine production. Infection was thought to have 

resulted from environmental contamination after the spill of a liquid 

containing a high concentration of the organism. As a result, MDHHS 

recommended that the facility improve its infection control 

procedures to better protect workers. This outbreak highlights 

occupational risks that can be associated with the manufacture of 

veterinary biologics involving human pathogens.



The vaccine production facility is located in a town of approximately 

8000 persons in central Maine, has 74 employees, and manufactures 

viral and bacterial vaccines for poultry. The facility had been last 

inspected in August 2005 by staff members of the USA Department of 

Agriculture's (USDA's) Center for Veterinary Biologics, which 

regulates animal vaccine production facilities. The facility 

maintains stock cultures of 4 phage types of _S._ Enteritidis (8, 

14B, 23, and 24) for vaccine production.



On 9 Nov 2006, a spill of approximately 1-1.5 liters [1-1.58 quarts] 

of liquid occurred in the fermentation room of the production area of 

the facility; the liquid contained 20 000 000 000 to 50 000 000 000 

colony forming units per milliliter of _S._ Enteritidis phage type 8. 

The room was unoccupied at the time the spill occurred. The worker 

who was regularly assigned to this room reported finding liquid 

overflowing onto the floor from the fermentation apparatus when he 

entered the room, wearing personal protective equipment (PPE) (e.g., 

biohazard suit, hat, booties, mask, and gloves). He cleaned up the 

spill using a mop, a 5 percent bleach solution, and a commercial 

disinfectant effective against the organism. The mop was autoclaved 

before disposal in a room 30 feet away (room A) used for cleaning and 

sterilizing laboratory supplies and equipment for vaccine production. 

The facility did not have a written spill procedure or a spill 

clean-up kit. On 15 Nov 2006, the worker who cleaned up the spill had 

diarrhea of 1 day's duration. He did not miss work, seek medical 

care, or submit a stool specimen for culture.



On 13 Dec 2006, a total of 67 (91 percent) of the 74 employees were 

interviewed at the facility by MDHHS staff members using a standard 

questionnaire. A case of diarrheal illness was defined as 3 or more 

loose or watery stools in a 24 hour period since 1 Nov 2006. 21 (31 

percent) of the 67 employees interviewed had illness that was 

consistent with the case definition, with onset ranging from 8 Nov 

2006 to 11 Dec 2006 (Figure [for figure, see original URL - Mod.LL]). 

recall the exact day she became ill. When interviewed on 29 Nov 2007, 

she reported becoming ill approximately 3 weeks earlier; therefore, 



In addition to diarrhea, patients reported fatigue (86 percent), 

cramps (86 percent), body aches (71 percent), nausea (62 percent), 

headache (57 percent), chills (57 percent), fever (43 percent), 

vomiting (43 percent), and blood in stool (29 percent); none of the 

employees were hospitalized. No secondary cases in family members 

were identified. 5 of 8 stool specimens from 8 patients submitted for 

culture were positive for _S._ Enteritidis.



Among 33 workers in the production area, 18 (55 percent) had illness 

consistent with the case definition, compared with 3 (9 percent) of 

percent confidence interval = 2.0-19.0). When analysis was restricted 

to workers in the production area, the strongest association with 

illness was working in room A. 18 (69 percent) of 26 employees who 

worked in room A (including those who did so intermittently) became 

ill, compared with none of the 7 production-area workers who did not 

work in room A (p=0.002). During multiple visits to the facility, 

investigators noted inadequate handwashing and lack of personal 

protective equipment. Aside from working in room A, none of the 

exposures examined were significantly associated with illness.



On 30 Nov 2006, staff members collected 15 environmental swab 

specimens from the production area; the swabs were processed by a 

commercial laboratory used by the vaccine manufacturer. 19 additional 

environmental swabs from room A were collected and processed by MDHHS 

on 19 Dec 2006. All environmental swabs were negative for 

_Salmonella_. 6 drinking water samples from 3 sites in the facility 

were collected on 30 Nov 2006 and processed by MDHHS; all were tested 

for _Escherichia coli_ as a marker for bacterial contamination. All 

the samples were negative for _E. coli_. Testing of water samples for 

_E. coli_ and fecal coliform also was conducted by the manufacturer; 

the results were negative.



Isolates of _S._ Enteritidis from 4 patients and the 4 vaccine stock 

cultures from the facility underwent pulsed field gel electrophoresis 

(PFGE) testing with two enzymes (XbaI and BlnI) by MDHHS and were 

determined to be indistinguishable. Phage typing was then performed 

on the isolates by the National Microbiology Laboratory of Canada in 

collaboration with CDC. Isolates from all 4 patients were phage type 

8, matching the phage type of the spilled stock culture.



PFGE and phage typing also were performed on all 7 _S._ Enteritidis 

isolates from ill Maine residents with no connection to the 

vaccine-production facility that were submitted to MDHHS during 

Oct-Nov 2006. The isolates were from 4 of Maine's 16 counties; none 

were from the county where the vaccine facility was located. All 7 

isolates were indistinguishable from the phage type 8 isolates by 

PFGE testing on the 1st enzyme (XbaI); 7 of the 7 isolates were 

tested on the 2nd enzyme (BlnI), and all 5 matched the phage type 8 

isolates. However, when phage typed, all 7 isolates were determined 

to be phage type 13A.





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Salmonella infections usually are acquired by eating contaminated 

food; however, some outbreaks have been associated with environmental 

contamination (1,2). Salmonella can survive in the environment for 

months (3), and the incubation period is 6-72 hours (4). Although the 

exact mechanism for infection of workers in this outbreak remains 

unknown, environmental contamination of room A likely was the source 

of the infection.



Workers might have become infected through hand-to-mouth activities 

after touching contaminated surfaces in room A. This mode of 

transmission is plausible because 1) the materials used in the 

clean-up of the spill were processed in room A before disposal, 2) 

the phage type of the organism among 4 ill employees (type 8) was the 

same as that of the stock culture involved in the spill and different 

from that of the 7 isolates from other cases (type 13A) reported in 

Maine during the same approximate period, 3) a strong epidemiologic 

association was determined between illness and working in room A, and 

4) inadequate handwashing practices and lack of protective equipment 

were noted in room A. Person-to-person transmission also might have 

occurred because some persons continued to work at the facility while ill.



The findings in this report are subject to at least 3 limitations. 

1st, staff members at the vaccine-production facility did not 

document details of the spill that occurred on 9 Nov 2007 until 20 

days later, which might have introduced recall bias. 2nd, 

environmental specimens were not obtained until 3 weeks after the 

spill had occurred; routine cleaning and disinfecting had occurred 

during this interval. Finally, because of the clonal nature of _S. 

Enteritidis, PFGE testing and phage typing alone might not be able to 

provide definitive strain discrimination; additional typing methods 

might be required (5).



MDHHS recommended that the facility improve hand-washing practices 

among employees and, especially in room A, the use of protective 

equipment, including gloves and (where splashes might occur) gowns 

and face shields. MDHHS further recommended creation of procedures 

for handling spills and routinely disinfecting work areas and advised 

ill employees not to work until their symptoms resolved. Results of 

the investigation were shared with USDA, the Maine Department of 

Labor, and the Occupational Safety and Health Administration. USDA 

reinspected the facility in January 2007 and began a follow-up visit 

on 28 Aug 2007.



salmonellosis among children attending a reptile exhibit at a zoo. J 

salmonellosis at elementary schools associated with dissection of owl 

4. Heymann DL, ed. Control of communicable diseases manual. 18th ed. 

of Salmonella Enteritidis PFGE pattern SENXAI.0003 and SENBNI.0003, 



--



[The issues related to this cluster seem overtly clear. A laboratory 

accident results in a spill, and an inadequately documented clean-up 

together with poor infection control practices among the workers 

resulted in the outbreak of cases. - Mod.LL]



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