Outbreak of Powassan Encephalitis Maine and Vermont, 1999-2001

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nal fluid (CSF) contained 40 white blood Her clinical examination showed agita- Outbreak of cells (WBCs)/mm3 (normal: Ͻ4/mm3) tion without confusion, ataxia, bilat- (87% lymphocytes) with elevated pro- eral lateral gaze palsy, and dysarthria. Powassan tein (96 mg/dL; normal: 20-50 mg/dL). CSF contained 148 WBCs/mm3 (46% Encephalitis— Magnetic resonance imaging (MRI) neutrophils, 40% lymphocytes). Dur- revealed parietal changes consistent with ing hospitalization, she developed al- Maine and Vermont, microvascular ischemia or demyelinat- tered mental status, generalized muscle 1999-2001 ing disease. No causes for his apparent weakness, and complete ophthalmople- stroke were found. After 22 days of hos- gia. An electroencephalogram (EEG) in- MMWR. 2001;50:761-764 pitalization, he was discharged to a reha- dicated diffuse encephalitis, and a MRI bilitation facility. Nearly 3 months after showed bilateral temporal lobe abnor- POWASSAN (POW) VIRUS, A NORTH symptom onset, he remains in the facil- malities consistent with microvascular American tickborne flavivirus related to ity and is unable to move his left arm or ischemia or demyelinating disease. Af- the Eastern Hemisphere’s tickborne en- leg. Serum specimens and CSF col- ter 13 days, she was transferred to a re- cephalitis viruses,1 was first isolated from lected 3 days after hospitalization habilitation facility where she re- a patient with encephalitis in 1958.1,2 revealed POW virus-specific IgM; neu- mained for 2 months. Nine months after During 1958-1998, 27 human POW en- tralizing antibody (1:640 titer) also was onset of symptoms, she was walking and cephalitis cases were reported from found in serum specimens. Although had regained her strength, but the oph- Canada and the northeastern United some cross-reaction with WNV and St. thalmoplegia continued. A serum speci- States.3 During September 1999-July Louis encephalitis (SLE) virus occurred men collected 19 days after illness on- 2001, four Maine and Vermont resi- in the IgM assay, no neutralizing anti- set was positive for POW virus-specific dents with encephalitis were found to body was found. IgM and neutralizing antibody (1:640 be infected with POW virus. These per- The patient had not left Maine for 25 titer) and negative for WNV and SLE sons were tested for other arbovirus in- years. On ecologic investigation, over- virus antibodies. fections found in the northeast after test- grown bushes, leaf piles, and stacks of The patient had not left Maine in sev- ing for West Nile virus (WNV) infection old lumber and scrap metal covered his eral months before illness onset. Dur- was negative. This report describes these property. Family members reported see- ing two visits to a rural vacation home four cases, summarizes the results of eco- ing woodchucks, skunks, and squirrels in the month before illness onset, the pa- logic investigations, and discusses a po- on the property. During the 2 weeks be- tient removed several squirrel nests but tential association between ticks that in- fore illness, the patient’s main activi- reported no contact with ticks or ro- fest medium-sized mammals and the risk ties were lying on the ground repairing dents. One month after illness onset, an for human exposure to POW virus. The a boat hull and yard work. Approxi- ecologic evaluation of her primary home findings underscore the need for per- mately 6 weeks after illness onset, nine noted a well-manicured suburban prop- sonal protective measures to prevent tick medium-sized mammals were trapped erty near brush and woodlands. No evi- bites and continued encephalitis sur- on or near the patient’s property. Col- dence of medium-sized mammals was veillance. lections from these mammals and the found, and only three Ix. scapularis were grassy and brushy areas of the property collected; no POW virus was isolated. Case Reports yielded 31 ticks (Ixodes cookei). Tests for Nine months after illness onset, an eco- Case 1. In June 2001, a 70-year-old man POW virus infection were conducted at logic evaluation of the patient’s vaca- from Kennebec County, Maine, was CDC. Of the nine mammal serum tion home found several mammals, but taken to a local hospital with general- samples, four (two woodchucks and two none had ticks, and no serology samples ized muscle weakness, somnolence, diar- skunks) contained neutralizing anti- were collected. rhea, and anorexia. On clinical exami- body to POW virus, but no virus was iso- Case 3. In July 2000, a 25-year-old nation, he had a fever of 104.7°F lated from the ticks. man from Waldo County, Maine, sought (40.4°C), leukocytosis of 11,500/mm3 Case 2. In September 2000, a 53- medical care at a local hospital for fe- (normal: 4,300-10,800/mm3), decreased year-old woman from York County, ver of 101.3°F (38.5°C), headache, vom- renal function, and anemia. He subse- Maine, sought medical care at a local iting, somnolence, and confusion. On quently developed left-sided hemiple- hospital for loss of balance, visual dis- clinical examination, the patient had dif- gia and marked confusion. Cerebrospi- turbance, and fever of 103°F (39.4°C). ficulty answering simple questions and

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was intermittently uncooperative. He len, MD, Veterans Affairs Medical Center, White River fore they attach or as soon after attach- Junction; P Tassler, PhD, Vermont Dept of Health. Ar- had bilateral hand twitching, muscle bovirus Diseases Br and Bacterial Zoonoses Br, Div of ment as possible. Checking family pets weakness, and pronounced lip smack- Vector-Borne Infectious Diseases, National Center for also can prevent ticks from entering the ing. CSF contained 920 WBCs/mm3 Infectious Diseases; and an EIS Officer, CDC. home. Because Ix. cookei are often found (74% lymphocytes) with elevated pro- on woodchucks and skunks and may be tein (77 mg/dL). EEG showed diffuse CDC Editorial Note: These four cases the primary vector of POW virus, envi- background slowing consistent with en- of POW encephalitis are the first re- ronmental controls reducing human cephalitis. After 11 days of hospitaliza- ported in Maine and Vermont and the contact with small and medium-sized tion, he was transferred to a rehabilita- first in the United States since 1994.4 mammals should reduce risk for expo- tion facility. When discharged home 44 Since the introduction of WNV into the sure to POW virus-infected ticks. Per- days later, the patient required assis- northeastern United States in 1999,5 test- sons should keep areas adjacent to their tance to stand and perform daily activi- ing for POW virus and other arbovi- home clear of brush, weeds, trash, and ties. Serum specimens and CSF col- ruses that cause encephalitis has in- other elements that could support small lected 3 days after illness onset were creased (CDC, unpublished data, 2001). and medium-sized mammals. When re- negative for antibody to WNV and SLE These cases were identified as a direct moving rodent nests, avoid direct con- virus but positive for POW virus- result of requests for WNV testing. As tact with nesting materials and use sealed specific IgM antibody. The serum sample surveillance continues, knowledge of the plastic bags for disposal and to prevent also had neutralizing antibody (1:80 ti- epidemiology of POW virus in the direct contact with ticks. ter) to POW virus. At the time of ill- United States may increase. Because of the lack of awareness and ness onset, the patient worked as a log- In North America, POW virus has the need for specialized laboratory tests ger and lived in rural Maine where he been isolated from four tick species, in- to confirm diagnosis, the frequency of raised livestock. cluding Ix. cookei, Ix. marxi, Ix. spinipa- POW encephalitis may be greater than Case 4. In September 1999, a 66- lpus, and Dermacentor andersoni; a vari- previously suspected. POW encephali- year-old man from Washington County, ant POW virus also has been isolated tis should be included in the differen- Vermont, sought medical care at a hos- from Ix. scapularis; and evidence of in- tial diagnosis of all encephalitis cases oc- pital for somnolence, severe head- fection has been found in 38 mammal curring in the northern United States, ache, increasing confusion, and bilat- species, primarily woodchucks.1,6 Un- especially the northeast. Laboratory tests eral leg weakness that developed over like Ix. scapularis, the primary vector for for POW virus infection are not com- 6 days. On clinical examination, he was Lyme disease, Ix. cookei rarely search for mercially available but can be re- afebrile but had slow speech, memory hosts on vegetation and are often found quested through state public health labo- loss, a wide-based gait, and bilateral in or near the nests or burrows of me- ratories for testing at CDC. Awareness weakness in proximal lower extremi- dium-sized mammals. Infections have should be promoted among clinicians ties. CSF contained 54 WBCs/mm3 occurred from May to December, with and public health staff, and tick-bite pre- (95% lymphocytes) and elevated pro- a peak during June-September when vention strategies emphasized for the tein (67 mg/dL). An EEG showed dif- ticks are most active.1 Although nei- general public. fuse background slowing consistent ther the first or second patients re- with encephalitis. When discharged called tick bites, ecologic investiga- REFERENCES* home 11 days later, he could walk but tions suggest that their illnesses resulted 1. Artsob H. Powassan encephalitis. In: Monath T, ed. The arboviruses: epidemiology and ecology. Volume had cognitive difficulties, including se- from visiting or living in areas where IV. Boca Raton, Florida: CRC Press, 1988:29-49. vere memory lapses. Serum speci- ticks are common. As with many infec- 2. McLean DM, Donohue WL. Powassan virus: isola- tion of virus from a fatal case of encephalitis. Can Med mens collected 19 days after illness on- tious agents transmitted by Ixodid ticks, Assoc J 1958;80:708-11. set contained POW virus-specific IgM few infected persons recalled tick bites 3. Gholam BIA, Puksa S, Provias JP. Powassan and neutralizing antibody (1:640 ti- because these ticks are small and can be encephalitis: a case report with neuropathology and literature review. Can Med Assoc J 1999;161: 3 ter) but no antibody to WNV and SLE easily missed. 1419-22. virus. During the month before illness POW encephalitis is associated with 4. CDC. Arboviral disease—United States, 1994. MMWR 1995;44:641-4. onset, the patient traveled frequently to significant long-term morbidity and has 5. Nash D, Mostashari F, Fine A, Miller J, O’Leary D, a vacation home where he saw numer- a case-fatality rate of 10%-15%.1,3 Be- Murray K. The outbreak of West Nile virus infection in the New York City area in 1999. N Engl J Med 2001; ous squirrels and skunks. cause there is no vaccine or specific 344:1807-14. therapy for POW encephalitis, the best 6. Ebel GD, Spielman A, Telford SR. Phylogeny of Reported by: T Courtney, MD, Southern Maine Medi- North American Powassan virus. J Gen Vir 2001;82: cal Center, Biddeford; S Sears, MD, J Woytowicz, MD, means of prevention is protection from 1657-65. MaineGeneral Medical Center, Augusta; D Preston, tick bite. This includes using insect re- MD, MaineGeneral Medical Center, Waterville; R *Reference to non-CDC sites on the Internet are pro- Smith, MD, P Rand, MD, E Lacombe, M Holman, C pellents, wearing light-colored cloth- vided as a service to MMWR readers and do not con- Lubelczyk, Lyme Disease Research Laboratory, Maine ing with long sleeves and pants tucked stitute or imply endorsement of these organizations Medical Center Research Institute, Portland; G Beck- or their programs by CDC or the U.S. Department of ett, MPH, E Pritchard, MS, K Gensheimer, MD, State into socks or boots, avoiding or clear- Health and Human Services. CDC is not responsible Epidemiologist, Maine Dept of Human Svcs. A Bee- ing brushy areas, and removing ticks be- for the content of pages found at these sites.

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Of 24 isolates tested at a clinical labo- Dubuque County Board of Health; AJ Behnke, United Clinical Laboratories, Dubuque; MS DeMartino, AK Shigellosis Outbreak ratory, 16 (67%) were resistant to am- Houston, Univ of Iowa Hygienic Laboratory, Iowa City, picillin and sensitive to trimethoprim- Iowa. Div of Bacterial and Mycotic Diseases and Div Associated With an of Parasitic Diseases, National Center for Infectious Dis- sulfamethoxazole, cefotaxime, and eases, CDC. Unchlorinated levofloxacin. Illness onset among primary case- CDC Editorial Note: In this outbreak, Fill-and-Drain patients occurred during June 12-14. the drain-and-fill pool contained mu- Wading Pool— The median age was 6 years (range: 1-31 nicipal water (0.4-0.5 ppm free avail- years); 23 (51%) were female. Symp- able chlorine) with no subsequent chlo- Iowa, 2001 toms included diarrhea (100%), nau- rination so that the pool was probably sea (51%), vomiting (47%), bloody di- unchlorinated for most of the time it was MMWR. 2001;50:797-800 arrhea (39%), and headache (29%). in use. Inadequate disinfection of this 1 figure omitted Seven (16%) patients were hospital- pool, combined with heavy use by dia- ized. Pool exposure was associated sig- per- and toddler-aged children, who are ON JUNE 15, 2001, LOCAL PHYSICIANS RE- nificantly with illness (risk ratio=5.7; often incontinent and may have an in- ported 11 cases of diarrhea to a county 95% confidence interval=1.6-20.4). Ill- creased prevalence of enteric infec- health department. Stool samples from ness onset among the 24 secondary case- tions, created a favorable environment two of these persons were culture con- patients occurred during June 15-22. for transmission of shigellosis. firmed as Shigella sonnei; one person The median age was 24 years (range: Transmission of shigellosis over sev- was hospitalized. A preliminary inves- 0-63 years); 14 (58%) were female. eral days may have been a result of the tigation found that nine of these per- The pool, which has been in opera- residual contaminated water left in the sons recently had visited a large city tion for approximately 60 years, is 40 feet pipes after draining the pool and per- park with a wading pool. The Iowa De- in diameter, has a maximum depth of sons with diarrhea visiting the pool on partment of Public Health was asked to 14 inches, and has a 9400-gallon capac- subsequent days. The infectious dose for assist in an investigation of this out- ity. It is frequented by diaper- and tod- Shigella1 is low; as a result, a small vol- break. This report summarizes the re- dler-aged children and as many as 20-30 ume of ingested water can cause infec- sults of the investigation, which impli- children may be in the pool at one time. tion. The lack of chlorination that led cated the inadequately disinfected The pool is a “fill-and-drain” system and to transmission of shigellosis in this wad- wading pool as the source of the out- is filled each morning with potable city ing pool also increased the risk for break and presents strategies for pre- water through a direct inlet pipe and a spreading life-threatening pathogens venting such outbreaks. centrally located fountain; it is drained such as E. coli O157:H7. Beginning on June 15, telephone in- and left empty each evening. The pool This outbreak together with surveil- terviews were conducted using a ques- includes a backflow device but has no lance data that suggest an increase in dis- tionnaire that included information recirculation or disinfection system (i.e., ease outbreaks associated with recre- about demographics, illness history, par- pump, filter, or mechanical disinfec- ational water exposure2 illustrate the ticipation in group gatherings, water ac- tion system). Each morning before fill- need for strict adherence of recre- tivities, and use of the park or wading ing, the pool is rinsed with a high- ational water venues to existing health pool. Ill persons were asked to identify pressure washer and is scrubbed with a codes, enforcement of these codes, and others who were at the park or had simi- chlorine cleanser twice weekly. How- education of pool operators about ad- lar symptoms. A primary case was de- ever, chlorine levels were not moni- equate disinfection and maintenance of fined as self-reported diarrhea in a per- tored and chlorine was not added to the pool water quality. Improved facility de- son within 72 hours of visiting the park pool water. Samples from the pool and sign and adequate water treatment can during June 11-13. A secondary case was other water sources in the park, includ- decrease the risk for transmission of ill- defined as self-reported diarrhea in a per- ing drinking fountains and faucets, were ness. In addition to improved pool de- son within 72 hours of household con- collected on June 15 and tested by the sign and improved management and tact with a primary case-patient. Colilert test, a rapid procedure to de- maintenance, increased education of Of 89 persons interviewed, 69 met one termine the presence of fecal coli- pool staff and the public about the po- of the case definitions. Of these, 45 forms. One pool sample tested positive tential for spreading recreational water (65%) were categorized as primary cases for fecal coliforms and Escherichia coli. illness and development of strategies for and 24 (35%) as secondary cases. Stool The pool was closed on June 15. reducing the spread of swimming- samples from 16 primary case-patients related illness is crucial to decreasing Reported by: CJ Lohff, MD, GM Nissen, ML Mag- 3 and 10 secondary case-patients were nant, MP Quinlisk, MD, State Epidemiologist, Iowa transmission. laboratory confirmed as S. sonnei, and Dept of Public Health; CL Tieskoetter, PL Kowalski, Swimming is a shared water activity Visiting Nurse Association of Dubuque; PA Buss, PhD, all 26 isolates were indistinguishable by Dubuque County Health Dept; TA Link, MR Corri- that can result in disease transmission, pulse field gel electrophoresis (PFGE). gan, City of Dubuque Health Svcs Dept; JP Viner, MD, even with adequate chlorination, when

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water becomes contaminated and is sub- REFERENCES erinary clinic; 10 of 20 persons had ab- sequently swallowed. Strategies for pre- 1. Acheson DK, Bennish ML. Shigella and Enteroin- dominal cramps and diarrhea, and two vention include (1) not swimming when vasive Escherichia coli. In: Blazer MJ, Smith PD, Rav- of the 10 had bloody diarrhea. The me- din JI, Greenberg HB, Guerrant RL, eds. Infections of ill with diarrhea, (2) not swallowing rec- the gastrointestinal tract. New York, New York: Raven dian age of the ill persons was 31 years reational water, and (3) practicing good Press, 1995. (range: 19-44 years), the median du- 2. Barwick RS, Levy DA, Beach MJ, Craun GF, Cal- hygiene when using a pool. Parents deron RL. Surveillance for waterborne-disease out- ration of illness was 7 days (range: 4-12 should take children on bathroom breaks—United States, 1997-1998. In: CDC surveil- days), and four persons sought medi- breaks regularly, use appropriate dia- lance summaries (May). MMWR 2000;49(no. SS-4). cal care. The index patient reported car- 3. CDC. Healthy swimming 2001. Available at http:// per changing areas, wash hands after us- www.healthyswimming.org. Accessed August 2001. ing for several kittens with diarrhea 1 ing the toilet or changing diapers, and 4. CDC. Shigella surveillance: annual tabulation sum- or 2 days before illness onset; stool mary, 1999. Atlanta, Georgia: US Department of Health shower before entering the pool. Swim and Human Services, CDC, 2000. specimens were not cultured and the pants and diapers do not prevent leak- 5. CDC. Community outbreaks of shigellosis— kittens died. All 10 ill employees ate age of diarrhea; therefore, they are not United States. MMWR 1990;39:509-13,519. meals in the clinic and had no com- an acceptable solution for a child with mon exposures outside the clinic. Stool diarrhea and are not a substitute for fre- specimens from five ill employees quent diaper changing. Outbreaks of yielded S. Typhimurium. All isolates Approximately 10,000 cases of S. son- Multidrug-Resistant were indistinguishable by pulsed-field nei are diagnosed each year in the United gel electrophoresis (PFGE); reacted to States, and most occur in young chil- Salmonella phage but did not conform to a defini- dren.4 Subsequent to the outbreak de- tive phage type; and were resistant to scribed in this report, a community- Typhimurium ampicillin, ceftriaxone, cephalothin, wide outbreak of shigellosis involving Associated With chloramphenicol, clavulanic acid/ several local day care centers occurred; amoxicillin, gentamicin, kanamycin, PFGE patterns were identical for both Veterinary streptomycin, sulfamethoxazole, and swimming-related and community- Facilities—Idaho, tetracycline. outbreak isolates. The ease with which single outbreaks can expand into com- Minnesota, and Minnesota munitywide outbreaks of S. sonnei5 un- Washington, 1999 The Minnesota Department of Health derscores the importance of educating (MDH) routinely receives animal S. Ty- the community about potential modes MMWR. 2001;50:701-704 phimurium isolates from the Minne- of transmission (e.g., child care facili- sota Veterinary Diagnostic Laboratory. ties, food handlers, and swimming) and CDC RECEIVED REPORTS IN 1999 FROM In 1999, MDH tested S. Typhimurium the implementation of appropriate pre- three state health departments of out- isolates from nine cats and seven hu- vention recommendations during outbreaks of multidrug-resistant Salmo- mans that were indistinguishable by breaks (e.g., thorough hand washing af- nella serotype Typhimurium infec- PFGE. All isolates were resistant to am- ter using restrooms, changing diapers, tions in employees and clients of small picillin, chloramphenicol, streptomy- and before handling/preparing food, en- animal veterinary clinics and an ani- cin, sulfamethoxazole, and tetracy- forcement of exclusion criteria at child mal shelter. Salmonella infections usu- cline (R-type ACSSuT). Three cat and care facilities, and exclusion of persons ally are acquired by eating contami- two human isolates tested were defini- from swimming while ill with diarrhea). nated food; however, direct contact with tive type (DT) 104. The cats had died Child care facilities should follow strict infected animals, including dogs and in an animal shelter during September- hygiene recommendations, including su- cats, also can result in exposure and in- October at age 6-14 weeks as a result of pervised hand washing for young chil- fection.1 This report summarizes clini- infection. The median age of ill per- dren, and may consider refraining from cal and epidemiologic data about these sons was 6 years (range: 11 months-23 using water play tables and inflatable outbreaks and reviews methods of re- years), and the median duration of di- pools that may lead to transmission. In ducing the likelihood of Salmonella arrhea was 8 days (range: 5-11 days); all addition, communication with pool op- transmission in veterinary settings by persons sought medical care, and one erators about ongoing outbreaks may avoiding fecal-oral contact. was hospitalized for 4 days. An adult improve vigilance in maintaining disin- treated with ciprofloxacin shed S. Ty- fectant levels necessary to reduce the risk Idaho phimurium in stool at least 214 days af- for transmission among bathers at com- During September-October, the Idaho ter illness onset. munity pools. Additional information Department of Health and Welfare iden- A connection with the animal shel- about preventing recreational water tified through routine surveillance an ter was established for six of the seven illness is available at http://www outbreak of Salmonella infections human patients; four purchased cats .healthyswimming.org.3 among employees of a small animal vet- from the shelter during August-

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October and two attended the same day- United States are transmitted through mon multidrug-resistant Salmonella care center as an ill child who owned a food, Salmonella also is transmitted strains, accounted for 7% and 3% of cat from the shelter. One cat developed through exposure to contaminated wa- non-Typhi Salmonella isolates, respec- bloody diarrhea 1 day after adoption and ter, reptiles, farm animals, and pets.1 It tively.5 Investigations in the United onset of illness in the patient began 4 is unknown how the human patients in States have found associations be- days later. Two cats remained asymp- these outbreaks became infected with tween human infections caused by tomatic; however, the owner became ill Salmonella; however, the inadvertent in- R-type ACSSuT and R-type AKSSuT 77 days after adopting the cats. The out- gestion of animal feces or food con- strains of S. Typhimurium and con- break strain of S. Typhimurium was re- taminated with animal feces may have tact with cattle, including eating covered from one cat 115 days after occurred as the result of suboptimal and drinking unpasteurized dairy adoption. sanitation and hygienic practices in the products.6,7 S. Typhimurium DT104 veterinary facilities. Many cats in these R-type ACSSuT has been associated Washington facilities had a diarrheal illness that also with contact with pets in the United Through laboratory-based surveillance may have contributed to Salmonella Kingdom8; outbreaks described in this and patient interviews, the Washing- transmission. Even after recovery from report are the first to associate DT104 ton State Department of Health de- an acute episode of Salmonella gastro- with pets in the United States. tected in late 1999 an outbreak of Sal- enteritis, fecal shedding of Salmonella To prevent salmonellosis, persons monella infections associated with a can occur and may last several months. should wash their hands before eating small animal veterinary clinic. Stool In addition, the use of antimicrobial and after handling food. Immunosup- specimens from three ill persons yielded agents in veterinary facilities may have pressed persons should avoid animals S. Typhimurium, all three sought medi- contributed to transmission of multi- aged Ͻ6 months and animals with cal care, but none was hospitalized. One drug-resistant Salmonella by lowering diarrhea.9 Veterinary workers should ill person was a clinic employee and the the infectious dose needed for inges- wash their hands after handling pets, two others recently had brought their tion to cause illness in animals and in- especially after handling feces. These cats to the clinic, one for elective sur- creasing the likelihood of transmis- workers can further reduce their expo- gery and the other for a urinary tract in- sion to humans. Although outbreaks of sure to feces by wearing rubber or dis- fection. The cats developed diarrhea af- multidrug-resistant Salmonella with hu- posable gloves, and by removing gloves ter their discharge from the clinic and man and animal illness have been re- and washing their hands immediately the owners subsequently became ill. The ported in large animal veterinary facili- after finishing a task that involves con- clinic was the only common exposure ties (e.g., horse clinics),2,3 outbreaks tact with animal feces. Although there reported by the three ill persons. S. Ty- associated with small animal facilities have been no reports of Salmonella phimurium was isolated from 14 cats as- are rare. The outbreaks described in this transmission through splash expo- sociated with this clinic; some of the cats report demonstrate that small animals sures, workers might consider taking initially presented with diarrhea. Iso- shed Salmonella and that small animal measures to reduce splashes of feces to lates from ill persons and cats were in- facilities can serve as foci of transmis- the mouth when hosing or cleaning a distinguishable by PFGE. All isolates sion for Salmonella to other animals and kennel. All surfaces contaminated with were DT104 R-type ACSSuT. humans. feces should be cleaned and disinfected. No eating should be allowed in Reported by: H Ezell, B Tramontin, Idaho District In 1999, the most commonly iso- Health Dept; R Hudson, PhD, Idaho State Public Health lated Salmonella serotype in the United animal treatment or holding areas. Be- Laboratory; L Tengelsen, DVM, C Hahn, MD, State cause use of antimicrobial agents con- Epidemiologist, Idaho Dept of Health and Welfare. K States was S. Typhimurium, account- Smith, DVM, J Bender, DVM, D Boxrud, J Adams, Min- ing for 23% of laboratory-confirmed Sal- tributes to increasing resistance and nesota Dept of Health; R Frank, DVM, Univ of Min- 4 facilitates transmission of multidrug- nesota College of Veterinary Medicine, Dept of Vet- monella cases. Multidrug resistance erinary Diagnostic Medicine; K Culbertson, DVM, among S. Typhimurium isolates is com- resistant Salmonella, eliminating inap- Animal Humane Society, Golden Valley, Minnesota. mon; of human S. Typhimurium iso- propriate use of antimicrobial agents T Besser, DVM, D Rice, MS, Washington State Univ may help to prevent outbreaks of mul- College of Veterinary Medicine, Pullman; R Gautom, lates received at CDC through the PhD, R Pallipamu, M Goldoft, MD, J Grendon, DVM, National Antimicrobial Resistance tidrug-resistant Salmonella infections in J Kobayashi, MD, Washington Dept of Health. F An- veterinary facilities.10 gulo, DVM, T Barrett, PhD, S Rossiter, MPH, S Siva- Monitoring System, 46% were multi- palasingam, MD, J Wright, DVM, Foodborne and Di- drug-resistant; 61% of these were R-type arrheal Diseases Br, Div of Bacterial and Mycotic Diseases, National Center for Infectious Diseases, CDC. ACSSuT and 23% were R-type AKSSuT REFERENCES* (resistant to ampicillin, kanamycin, 10 available CDC Editorial Note: Although most of streptomycin, sulfamethoxazole, and *All MMWR references are available on the Internet the estimated 1.4 million Salmonella in- tetracycline). R-type ACSSuT and at http://www.cdc.gov/mmwr. Use the search func- fections that occur each year in the R-type AKSSuT, the two most com- tion to find specific articles.

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