Comparing healthcare needs by language: interpreted Arabic and Somali telehealth calls in two regions of Sweden, 2014-18.

BACKGROUND: Limited language fluency can impede healthcare system navigation. In Sweden, the national telehealth line (Healthcare Guide 1177) offers interpretation in Arabic and Somali. We compared calls by language to identify differences in healthcare use for immigrant populations, focusing on three contact causes: pregnancy; vomiting or nausea in children; and worry/anxiety. METHODS: We conducted a cross-sectional analysis of 3.9 million (n = 18 351 Arabic, n = 7199 Somali) telehealth calls (2014-18). Using multivariable logistic regression, we investigated associations between language of the call (Arabic, Somali, non-interpreted) and each contact cause. Potential confounders (age, region, year, and additionally for vomiting or nausea, month) and an interaction between age and language were considered. RESULTS: Compared with non-interpreted calls, interpreted calls were associated with increased odds of being for pregnancy, especially for 19 to 29-year-olds [adjusted odds ratio (aOR) (95% CI) = 4.04 (3.66-4.46) and 4.60 (4.05-5.23), for Arabic and Somali calls, respectively]. Vomiting or nausea showed similar results, with aOR increasing with age: from 0.90 (0.75-1.07) (Arabic, <1 year) to 3.79 (2.86-5.01) (Somali, 5-9 years). In contrast, in unadjusted analyses, Arabic and Somali calls were associated with decreased odds of being for worry/anxiety [OR = 0.47 (0.38-0.58) and 0.34 (0.21-0.50)], respectively, compared with non-interpreted calls. CONCLUSION: Our results suggest callers to the interpreted lines may need additional assistance navigating the healthcare system for pregnancy and for vomiting or nausea among children. These findings can inform healthcare services planning for immigrants to Sweden and highlight a novel use of telehealth data as a way to uncover disparities in healthcare use within a multi-linguistic population.

Estimated number of reported vaccine-preventable disease cases averted following the introduction of routine vaccination programs in Sweden, 1910-2019.

BACKGROUND: Routine childhood vaccination programs have had enormous positive public health impacts worldwide. However, in some areas, these benefits may be impeded by vaccine hesitancy and undervaccination. We estimated the number of reported cases of measles, pertussis, mumps and poliomyelitis averted in Sweden after the introduction of routine childhood vaccination programs. METHODS: We used annual national data on population size and the number of reported cases of measles (1911-2019), pertussis (1911-2019), mumps (1914-2019) and poliomyelitis (1910-2019) for Sweden. For each disease, we calculated the median and 95% confidence interval of the annual pre-vaccination incidence to estimate the number of counterfactual cases; that is, the estimated number of cases that would have been observed in the post-vaccination period had no vaccine been introduced (median incidence × average annual population). For the post-vaccination periods, we calculated reported cases averted and assumed all decreases were due to vaccines. RESULTS: In total, for all four diseases combined, over 2.1 million cases were reported over the respective surveillance periods. Since the introduction of vaccinations, we estimate that over 1.5 million reported cases of these four diseases combined have been averted: measles (633 091), pertussis (608 670), mumps (262 951) and poliomyelitis (58 240). However, due to underreporting, especially during pre-vaccination years, these are likely underestimates. CONCLUSIONS: Since the introduction of these routine childhood vaccination programs in Sweden, a substantial number of reported cases of vaccine-preventable diseases have been averted. Vigilance against both failure to vaccinate and undervaccination is necessary to prevent future increases of these vaccine-preventable diseases.

Estimating the burden of recurrent events in the presence of competing risks: the method of mean cumulative count.

Cumulative incidence has been widely used to estimate the cumulative probability of developing an event of interest by a given time, in the presence of competing risks. When it is of interest to measure the total burden of recurrent events in a population, however, the cumulative incidence method is not appropriate because it considers only the first occurrence of the event of interest for each individual in the analysis: Subsequent occurrences are not included. Here, we discuss a straightforward and intuitive method termed "mean cumulative count," which reflects a summarization of all events that occur in the population by a given time, not just the first event for each subject. We explore the mathematical relationship between mean cumulative count and cumulative incidence. Detailed calculation of mean cumulative count is described by using a simple hypothetical example, and the computation code with an illustrative example is provided. Using follow-up data from January 1975 to August 2009 collected in the Childhood Cancer Survivor Study, we show applications of mean cumulative count and cumulative incidence for the outcome of subsequent neoplasms to demonstrate different but complementary information obtained from the 2 approaches and the specific utility of the former.

All-cause and HIV-related mortality rates among HIV-infected patients after initiating highly active antiretroviral therapy: the impact of Aboriginal ethnicity and injection drug use.

BACKGROUND: Aboriginals are over-represented in Canada's HIV epidemic and are commonly infected with HIV via injection drug use (IDU); however, little is known about the impact of Aboriginal ethnicity on mortality after starting highly active antiretroviral therapy (HAART). Therefore, we compared mortality rates between Aboriginal and non-Aboriginal HIV patients and between IDU and non-IDU HIV patients after they initiated HAART. METHODS: We conducted a retrospective cohort study of antiretroviral-naïve patients starting HAART January 1999-June 2005 (baseline), followed until December 2005. We constructed two Cox proportional hazards models, one to estimate all-cause and one to estimate HIV-related mortality hazard ratios (HRs), considering sex, and baseline age, CD4 cell count, HIV RNA level, calendar year, and HAART regimen as potential confounders. RESULTS: The 548 study patients were followed for 1,889.8 person-years; 194 (35%) were Aboriginal, 255 (46%) were IDUs. We observed 55 deaths; 47% were HIV-related. In multivariable models, Aboriginals experienced higher all-cause (HR = 1.85, 95% CI = 1.05-3.26, p = 0.034) and HIV-related (HR = 3.47, 95% CI = 1.36-8.83, p = 0.009) mortality rates compared to non-Aboriginals; and, compared to patients with other exposures, IDUs experienced higher all-cause (HR = 2.45, 95% CI = 1.31-4.57, p = 0.005) but similar HIV-related (p = 0.27) mortality rates. CONCLUSIONS: Compared to non-Aboriginals, Aboriginal HIV patients suffer higher all-cause and HIV-related mortality rates after starting HAART. The strongest and most significant predictor of higher all-cause mortality was IDU. Future research should examine reasons for the observed poorer survival of Aboriginal and IDU HIV patients after initiating HAART to develop interventions to improve the prognosis for these vulnerable populations.

Interaction of prenatal bisphenols, maternal nutrients, and toxic metal exposures on neurodevelopment of 2-year-olds in the APrON cohort.

BACKGROUND: Epidemiological studies suggest that Bisphenol-A (BPA) is a developmental neurotoxicant, but the modifying effects of maternal nutrient status or neurotoxicant metal co-exposures have not been reported. Bisphenol-S (BPS) is being used as a BPA-alternative, but few epidemiological studies have evaluated its effects. OBJECTIVES: To examine if prenatal maternal BPA or BPS exposure are associated with children's neurodevelopment at two years of age while adjusting for effect-measure modification by sex, maternal nutrients, and co-exposure to neurotoxic metals. METHODS: Total BPA and BPS concentrations were analyzed in spot maternal urine from the second trimester; metals and maternal nutrient status were analyzed in blood. Child neurodevelopment was evaluated with the Bayley Scales of Infant Development-III (Bayley-III) at age 2 (394 maternal-child pairs) and linear regression was used to investigate associations. RESULTS: Among nutrients and neurotoxic metals, selenium (Se) and cadmium (Cd) were the most significant predictors of Bayley-III scale scores. Higher maternal Cd was significantly correlated with poorer motor performance (p < 0.01), and higher levels of maternal Se were significantly associated with poorer performance on the cognitive, motor, and adaptive behavior scales (p < 0.05). While maternal Cd did not modify relationships between bisphenol exposures and Bayley-III scores, both maternal Se and child sex were significant effect-measure modifiers. Associations between BPA exposure and social emotional scores were negative for boys (p = 0.056) but positive for girls (p = 0.046). Higher exposure to bisphenols was associated with lower motor scores among children with lower levels of maternal Se. CONCLUSION: Higher maternal Cd was associated with poorer motor development, but it was not an effect-measure modifier of bisphenols' effects on motor development. Maternal Se may be protective against adverse effects of bisphenols, and additional nutrient-bisphenol interaction studies examining sex-specific effects of BPA and BPS on child development are warranted.

Investigating novel approaches to tick-borne encephalitis surveillance in Sweden, 2010-2017.

Tick-borne encephalitis (TBE) is a vaccine-preventable, high-priority disease in Sweden, with increasing incidence. However, surveillance is limited to case reports. We investigated relationships between reported TBE incidence and syndromic surveillance data to determine if these novel data sources could provide earlier indications of disease activity. We retrospectively compared national, weekly (2010-2017) reported TBE incidence to the percentage of TBE-related a) searches on the main Swedish healthcare information website and b) calls to its telehealth service using Spearman's ρ to determine the most strongly correlated lags. We conducted a sub-analysis (2012-2017) of TBE-related Google Trends queries and compared the number of TBE-related media stories to each novel surveillance dataset. Healthcare website searches for "tbe" and "vaccine" combined, "tbe", "tick", and "tick bite" led case data by 12, 8, 7, and 6 weeks, respectively (ρ = 0.87-0.89); telehealth calls led by 4 weeks (ρ = 0.92; all p < 0.001). Correlations and lags for Google Trends and healthcare website searches were fairly similar to each other. In comparison, correlation between the different syndromic surveillance datasets and the number of media stories was lower (ρ = 0.25-0.56). We observed volume discrepancies between TBE incidence and the novel surveillance datasets during some years, particularly for web searches. Syndromic surveillance data were strongly correlated with and preceded case data by 4-12 weeks. Syndromic data may provide advanced awareness and earlier indications of TBE activity, which can improve timing and specificity of public health communications. The use of these data as supplements to notifiable disease data for national planning and preparedness in real-time should be investigated.

Disposition of perfluorinated acid isomers in Sprague-Dawley rats; part 1: single dose.

Perfluorinated acids (PFAs) and their precursors (PFA-precursors) exist in the environment as linear and multiple branched isomers. These isomers are hypothesized to have different biological properties, but no isomer-specific data are currently available. The present study is the first in a two-part project examining PFA isomer-specific uptake, tissue distribution, and elimination in a rodent model. Seven male Sprague-Dawley rats were administered a single gavage dose of approximately 500 microg/kg body weight perfluorooctane sulfonate (C(8)F(17)SO(3)(-), PFOS), perfluorooctanoic acid (C(7)F(15)CO(2)H, PFOA), and perfluorononanoic acid (C(8)F(17)CO(2)H, PFNA) and 30 microg/kg body weight perfluorohexane sulfonate (C(6)F(13)SO(3)(-), PFHxS). Over the subsequent 38 d, urine, feces, and tail-vein blood samples were collected intermittently, while larger blood volumes and tissues were collected on days 3 and 38 for isomer analysis by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). For all PFAs, branched isomers generally had lower blood depuration half-lives than the corresponding linear isomer. The most remarkable exception was for the PFOS isomer containing an alpha-perfluoromethyl branch (1m-PFOS), which was threefold more persistent than linear PFOS, possibly due to steric shielding of the hydrophilic sulfonate moiety. For perfluoromonomethyl-branched isomers of PFOS, a structure-property relationship was observed whereby branching toward the sulfonate end of the perfluoroalkyl chain resulted in increased half-lives. For PFHxS, PFOA, and PFOS, preferential elimination of branched isomers occurred primarily via urine, whereas for PFNA preferential elimination of the isopropyl isomer occurred via both urine and feces. Changes in the blood isomer profiles over time and their inverse correlation to isomer elimination patterns in urine, feces, or both provided unequivocal evidence of significant isomer-specific biological handling. Source assignment based on PFA isomer profiles in biota must therefore be conducted with caution, because isomer profiles are unlikely to be conserved in biological samples.

Disposition of perfluorinated acid isomers in Sprague-Dawley rats; part 2: subchronic dose.

Two major industrial synthetic pathways have been used to produce perfluorinated acids (PFAs) or their precursors: Telomerization and electrochemical fluorination (ECF). Products of telomer and ECF origin can be distinguished by structural isomer profiles. A mixture of linear and branched perfluoroalkyl isomers is associated with ECF. Telomer products characteristically consist of a single perfluoroalkyl geometry, typically linear. In biota, it is unclear if the isomer profile is conserved relative to the exposure medium and hence whether PFA isomer profiles in organisms are useful for distinguishing environmental PFA sources. A companion study suggested isomer-specific disposition following a single oral gavage exposure to rats. To confirm these findings under a more realistic subchronic feeding scenario, male and female rats were administered PFA isomers by diet for 12 weeks, followed by a 12-week depuration period. The diet contained 500 ng/g each of ECF perfluorooctanoate (PFOA, approximately 80% n-PFOA), ECF perfluorooctane sulfonate (PFOS, approximately 70% n-PFOS), and linear and isopropyl perfluorononanoate (n- and iso-PFNA). Blood sampling during the exposure phase revealed preferential accumulation of n-PFOA and n-PFNA compared to most branched isomers. Female rats depurated all isomers faster than males. Both sexes eliminated most branched perfluorocarboxylate isomers more rapidly than the n-isomer. Elimination rates of the major branched PFOS isomers were not statistically different from n-PFOS. Two minor isomers of ECF PFOA and one branched PFOS isomer had longer elimination half-lives than the n-isomers. Although extrapolation of these pharmacokinetics trends in rats to humans and wildlife requires careful consideration of dosage level and species-specific physiology, cumulative evidence suggests that perfluorocarboxylate isomer profiles in biota may not be suitable for quantifying the relative contributions of telomer and ECF sources.

Dynamic modeling of hepatitis C transmission among people who inject drugs.

To reach the WHO goal of hepatitis C elimination, it is essential to identify the number of people unaware of their hepatitis C virus (HCV) infection and to investigate the effect of interventions on the disease transmission dynamics. In many high-income countries, one of the primary routes of HCV transmission is via contaminated needles shared by people who inject drugs (PWIDs). However, substantial underreporting combined with high uncertainty regarding the size of this difficult to reach population, makes it challenging to estimate the core indicators recommended by the WHO. To support progress toward the elimination goal, we present a novel multi-layered dynamic transmission model for HCV transmission within a PWID population. The model explicitly accounts for disease stage (acute and chronic), injection drug use status (active and former PWIDs), status of diagnosis (diagnosed and undiagnosed) and country of disease acquisition (domestic or abroad). First, based on this model, and using routine surveillance data, we estimate the number of undiagnosed PWIDs, the true incidence, the average time until diagnosis, the reproduction numbers and associated uncertainties. Second, we examine the impact of two interventions on disease dynamics: (1) direct-acting antiviral drug treatment, and (2) needle exchange programs. As a proof of concept, we illustrate our results for a specific data set. In addition, we develop a web application to allow our model to be explored interactively and with different parameter values.

Influenza-like illness-related emergency department visits: Christmas and New Year holiday peaks and relationships with laboratory-confirmed respiratory virus detections, Edmonton, Alberta, 2004-2014.

BACKGROUND: Emergency department (ED) visit volumes can be especially high during the Christmas-New Year holidays, a period occurring during the influenza season in Canada. METHODS: Using daily data, we examined the relationship between ED visits for the chief complaint "cough" (for Edmonton, Alberta residents) and laboratory detections for influenza A and respiratory syncytial virus (RSV) (for Edmonton and surrounding areas), lagged 0-5 days ahead, for non-pandemic years (2004-2008 and 2010-2014) using multivariable linear regression adjusting for temporal variables. We defined these cough-related visits as influenza-like illness (ILI)-related ED visits and, for 2004-2014, compared Christmas-New Year holiday (December 24-January 3) and non-holiday volumes during the influenza season (October-April). RESULTS: Adjusting for temporal variables, ILI-related ED visits were significantly associated with laboratory detections for influenza A and RSV. During non-pandemic years, the highest peak in ILI-related visit volumes always occurred during the holidays. The median number of holiday ILI-related visits/day (42.5) was almost twice the non-holiday median (24) and was even higher in 2012-2013 (80) and 2013-2014 (86). Holiday ILI-related ED visit volumes/100 000 population ranged from 56.0 (2010-2011) to 117.4 (2012-2013). In contrast, lower visit volumes occurred during the holidays of pandemic-affected years (2008-2010). CONCLUSIONS: During non-pandemic years, ILI-related ED visit volumes were associated with variations in detections for influenza A and RSV and always peaked during the Christmas-New Year holidays. This predictability should be used to prepare for, and possibly prevent, this increase in healthcare use; however, interventions beyond disease prevention strategies are likely needed.

Regional, seasonal, and antimicrobial resistance distributions of salmonella typhimurium in Canada: a multi-provincial study.

BACKGROUND: This study was conducted to describe the geographical and seasonal distributions of reported human Salmonella Typhimurium (ST) definitive type 104 (DT104) cases, to compare these characteristics to those of non-DT1 04 cases, and to investigate specific antimicrobial resistance (AMR) patterns in four Canadian provinces. METHODS: All laboratory-confirmed ST cases originating from passive reporting in Alberta, British Columbia, and Saskatchewan, and every second case in Ontario identified from December 1999 through November 2000 were investigated. RESULTS: A total of 470 human Salmonella Typhimurium cases were identified during the study period. DT104 was the most common phage type, although its incidence varied by province. The proportion of DT104 cases living in urban Ontario, British Columbia and Saskatchewan did not differ from the general population, but in Alberta, the DT104 cases were more likely to live in rural areas. Overall, DT104 isolates were more often R-type ACSSuT compared to non-DT104 cases, and R-type AKSSuT was often associated with DT208. DT104 cases displayed no seasonality whereas non-DT104 cases were more frequent in the summer than in the winter. INTERPRETATION: Our results suggest that DT104 and non-DT104 cases vary by province, urban vs. rural residential status and by resistance patterns. Lack of seasonality in the DT104 cases may indicate a lesser influence of the agro-environmental route (i.e., farm -manure - water and direct contact) compared to the agro-food route (i.e., farm - animals -food) for these infections. Strain characterization and integration of surveillance information related to ST from animal, food and humans is warranted.

Antimicrobial resistance among Salmonella and Shigella isolates in five Canadian provinces (1997 to 2000).

OBJECTIVE: To describe rates of antimicrobial resistance (AMR) among Salmonella and Shigella isolates reported in five Canadian provinces, focusing on clinically important antimicrobials. METHODS: The authors retrospectively investigated AMR rates among 6219 Salmonella and 1673 Shigella isolates submitted to provincial public health laboratories in Alberta, Newfoundland and Labrador, Ontario, Prince Edward Island and Saskatchewan from 1997 to 2000; these isolates were estimated to represent 41% of Salmonella cases and 72% of Shigella cases reported by the study provinces. RESULTS: Among Salmonella isolates, 27% (1704 of 6215) were resistant to ampicillin, 2.2% (135 of 6122) to trimethoprim/ sulfamethoxazole, 1.5% (14 of 938) to nalidixic acid, 1.2% (one of 84) to lomafloxacin and 0.08% (five of 6163) to ciprofloxacin. Among Shigella isolates, 70% (1144 of 1643) were resistant to trimethoprim/sulfamethoxazole, 65% (1079 of 1672) to ampicillin, 3.1% (eight of 262) to nalidixic acid, 0.49% (eight of 1636) to ciprofloxacin, 0.14% (one of 700) to ceftriaxone and 0.08% (one of 1292) to ceftazidime. CONCLUSIONS: Higher rates of resistance to clinically important antimicrobials (including ciprofloxacin) were observed among both Salmonella and Shigella isolates than has previously been reported. Current Canadian data on rates of AMR for these pathogens are required.

Improving Google Flu Trends estimates for the United States through transformation.

Google Flu Trends (GFT) uses Internet search queries in an effort to provide early warning of increases in influenza-like illness (ILI). In the United States, GFT estimates the percentage of physician visits related to ILI (%ILINet) reported by the Centers for Disease Control and Prevention (CDC). However, during the 2012-13 influenza season, GFT overestimated %ILINet by an appreciable amount and estimated the peak in incidence three weeks late. Using data from 2010-14, we investigated the relationship between GFT estimates (%GFT) and %ILINet. Based on the relationship between the relative change in %GFT and the relative change in %ILINet, we transformed %GFT estimates to better correspond with %ILINet values. In 2010-13, our transformed %GFT estimates were within ± 10% of %ILINet values for 17 of the 29 weeks that %ILINet was above the seasonal baseline value determined by the CDC; in contrast, the original %GFT estimates were within ± 10% of %ILINet values for only two of these 29 weeks. Relative to the %ILINet peak in 2012-13, the peak in our transformed %GFT estimates was 2% lower and one week later, whereas the peak in the original %GFT estimates was 74% higher and three weeks later. The same transformation improved %GFT estimates using the recalibrated 2013 GFT model in early 2013-14. Our transformed %GFT estimates can be calculated approximately one week before %ILINet values are reported by the CDC and the transformation equation was stable over the time period investigated (2010-13). We anticipate our results will facilitate future use of GFT.

Poorer physical health-related quality of life among Aboriginals and injection drug users treated with highly active antiretroviral therapy.

OBJECTIVE: We compared the health-related quality of life (HRQL) of Aboriginal and non-Aboriginal HIV patients after they started highly active antiretroviral therapy (HAART) in Edmonton, Alberta and investigated whether clinical status (CD4 cell count and viral load) might explain any observed differences. METHODS: In 2006-2007, eligible patients who started HAART in 1997-2005 completed the MOS-HIV to measure HRQL. Using multiple linear regression models, we compared physical (PHS) and mental (MHS) health summary scores across four groups: Aboriginals infected with HIV via injection drug use (AB/IDUs); Aboriginal non-IDUs (AB/non-IDUs); non-Aboriginal IDUs (non-AB/IDUs); and non-Aboriginal non-IDUs (non-AB/non-IDUs). To assess whether clinical status could explain any observed group differences, we fitted a model adjusting for socio-demographics (age and sex) and years since starting HAART only and then additionally adjusted for current clinical status. RESULTS: Ninety-six patients were eligible (35% Aboriginal, 42% IDU). Adjusting for socio-demographics and years since starting HAART, AB/IDUs (p=0.008), AB/non-IDUs (p=0.002), and non-AB/IDUs (p=0.002) had lower PHS scores than non-AB/non-IDUs. After additionally adjusting for clinical status, these relationships remained significant for AB/non-IDUs (p=0.027) and non-AB/IDUs (p=0.048) but not for AB/IDUs (p=0.12). AB/IDUs and non-AB/IDUs tended to have worse MHS scores than non-AB/non-IDUs, but these relationships were not statistically significant and weakened after adjusting for current clinical status. CONCLUSIONS: AB/IDU, AB/non-IDUs, and non-AB/IDUs had significantly poorer physical HRQL than non-AB/non-IDUs. These differences appear to be partially explained by poorer clinical status, especially for AB/IDUs, which suggests that observed inequalities in physical HRQL may be diminished by improving patients' clinical status; for example, through improved adherence to HAART.

Quality of life of HIV patients in a rural area of western Uganda: impact of a community-based antiretroviral treatment program.

OBJECTIVE: Community-based antiretroviral treatment (CBART) programs should aim to achieve positive quality of life outcomes. The purpose of this study was to investigate changes in the health related quality of life (HRQOL) outcomes of patients in a CBART program supported by community volunteers in one sub-county in western Uganda located 50 km from the nearest urban centre. METHODS: We administered a translated version of the MOS-HIV survey and collected clinical data at baseline and after one year from 130 patients. Inclusion criteria included residency in the sub-county, eighteen years of age or, treatment-naïve, eligible for ART based on CD4 cell count <200 cells/mm3 or WHO clinical stage 3 or 4, and willing to accept daily treatment support by family/friends and to be visited by a community volunteer weekly. We assessed changes in physical health (PHS) and mental health (MHS) summary scores and examined associations between patient characteristics and changes in HRQOL. RESULTS: After one year, we observed significant increases in mean PHS (42.7 to 50.1; p<0.01) and MHS (43.5 to 49.5; p<0.01) scores. Lower age (p<0.01) and lower baseline PHS scores (p<0.01) were associated with increases in PHS scores and lower age (p=0.03) and lower baseline MHS scores (p<0.01) were associated with increases in MHS scores. Fifteen patients (12%) had reductions in their HRQOL after one year which were not associated with patient or clinical characteristics, including virological suppression. CONCLUSIONS: The observed improvements in HRQOL demonstrate that positive treatment outcomes can be achieved in CBART programs in rural Uganda. However, some patients appear to experience declines in their overall well-being, despite achieving virological suppression. HRQOL surveys can be useful in identifying these patients, who may require additional attention and support to achieve the full benefits of ART.

Increased burden of illness associated with antimicrobial-resistant Salmonella enterica serotype typhimurium infections.

This study investigated the burden of illness associated with 440 cases of Salmonella enterica serotype Typhimurium infection identified in Canada between December 1999 and November 2000. We categorized case subjects' infections by definitive phage type 104 (DT104) and antimicrobial-resistance patterns. These variables were then investigated as risk factors for hospitalization. Hospitalization was more likely to occur among case subjects whose infections were resistant to at least ampicillin, chloramphenicol and/or kanamycin, streptomycin, sulphamethoxazole, and tetracycline (R-type AK/CSSuT; odds ratio [OR], 2.3; P=.003), compared with case subjects with AK/CSSuT-susceptible infections, and among case subjects with non-DT104 R-type AKSSuT infections (OR, 3.6; P=.005), compared with case subjects with non-DT104 AKSSuT-susceptible infections. In contrast, hospitalization rates did not differ between case subjects with DT104 infections and case subjects with non-DT104 infections or between case subjects with DT104 R-type ACSSuT infections and case subjects with DT104 ACSSuT-susceptible infections. We estimated that 57% of the hospitalizations among AK/CSSuT case subjects and 72% of the hospitalizations among non-DT104 AKSSuT case subjects were attributable to the resistance patterns of the infections.