Paul Rivest

Severe Complications Associated with Varicella: Province of Quebec, April 1994 to March 1996

OBJECTIVE To determine the frequency and severity of serious complications associated with varicella in Quebec; the frequency and severity of cases of congenital varicella; and hospital costs associated with hospitalizations for varicella. STUDY DESIGN All hospitalizations related to varicella were identified through the use of a hospital data bank and pertinent data were collected from hospital records. SETTING Province of Quebec with a population of 6,895,960 people. STUDY POPULATION All cases with a principal or secondary diagnosis of varicella hospitalized in Quebec between April 1, 1994 and March 31, 1996. OUTCOME MEASURES Types of complications and reason for hospitalization, risk of complications and calculation of associated costs were studied. RESULTS Nine hundred nine eligible hospitalizations were identified between April 1, 1994 and March 31, 1996. In all, 583 (64.1%) hospitalizations were for the treatment of complications, 127 (14.0%) for administration of intravenous acyclovir and 199 (21.9%) for supportive care. Healthy people accounted for 644 (70.8%) hospitalizations and immunosuppressed individuals for 136 (15.0%). Among children, one-half of the principal complications were skin infections, while 13.5% and 8.4% of principal complications were pneumonia and neurological complications, respectively. Among adults, the most common complication was pneumonia, with a rate of 43.5%, followed by thrombocytopenia and skin infections, with rates of 22.2% and 14.8%, respectively. The complication rate was 29.2 cases/10,000 cases of varicella. CONCLUSIONS Although perceived as a benign childhood disease by the general population, varicella may be accompanied by severe complications. Morbidity associated with varicella is one of the elements that must be considered when evaluating the usefulness of varicella vaccine.

Strategies to prevent varicella among newly arrived adult immigrants and refugees: a cost-effectiveness analysis.

In temperate, industrialized countries, such as Canada, varicella is a common disease in childhood [1]. In tropical countries, for reasons that are not entirely clear, varicella occurs among young adults. Seroprevalence data from tropical regions suggest that up to 30% of individuals are susceptible to varicella at 20 years of age, and 5%-10% remain susceptible at 30 years of age [2, 3]. There have been many reported outbreaks of varicella in immigrant populations in industrialized countries, suggesting that foreign-born adults are disproportionately susceptible [4-6]. Recent immigrants also have a high risk of exposure, because many are the parents of young children, who have a high annual incidence of varicella unless they are vaccinated. Varicella is more severe in adults than in children

Tuberculosis and homelessness in Montreal: a retrospective cohort study

BackgroundMontreal is Canadas second-largest city, where mean annual tuberculosis (TB) incidence from 1996 to 2007 was 8.9/100,000. The objectives of this study were to describe the epidemiology of TB among homeless persons in Montreal and assess patterns of transmission and sharing of key locations.MethodsWe reviewed demographic, clinical, and microbiologic data for all active TB cases reported in Montreal from 1996 to 2007 and identified persons who were homeless in the year prior to TB diagnosis. We genotyped all available Mycobacterium tuberculosis isolates by IS6110 restriction fragment length polymorphism (IS6110-RFLP) and spoligotyping, and used a geographic information system to identify potential locations for transmission between persons with matching isolates.ResultsThere were 20 cases of TB in homeless persons, out of 1823 total reported from 1996-2007. 17/20 were Canadian-born, including 5 Aboriginals. Homeless persons were more likely than non-homeless persons to have pulmonary TB (20/20), smear-positive disease (17/20, odds ratio (OR) = 5.7, 95% confidence interval (CI): 1.7-20), HIV co-infection (12/20, OR = 14, 95%CI: 4.8-40), and a history of substance use. The median duration from symptom onset to diagnosis was 61 days for homeless persons vs. 28 days for non-homeless persons (P = 0.022). Eleven homeless persons with TB belonged to genotype-defined clusters (OR = 5.4, 95%CI: 2.2-13), and ten potential locations for transmission were identified, including health care facilities, homeless shelters/drop-in centres, and an Aboriginal community centre.ConclusionsTB cases among homeless persons in Montreal raise concerns about delayed diagnosis and ongoing local transmission.

The effectiveness of serogroup C meningococcal vaccine estimated from routine surveillance data

Serogroup C meningococcal vaccine effectiveness was estimated from routine surveillance data, based on a comparison of the proportion of vaccine and non-vaccine serogroups in vaccinated and unvaccinated reported cases. Between 1 April 1993 and 31 March 1998, 109 eligible cases were reported. Among the 54 cases caused by serogroup C, 38 had been vaccinated. Among the 55 cases caused by non-vaccine serogroups, 49 had been vaccinated. Vaccine effectiveness was estimated at 71% (95% CI: 21-89%), a value similar to that obtained in the same population by a cohort study. Effectiveness was lower in children immunized before the age of 10. This demonstrates that meningococcal vaccine effectiveness can be estimated from information obtained routinely from cases only, as an alternative to the more expensive cohort or case-control designs.

Completion Rates of Treatment for Latent Tuberculosis Infection in Quebec, Canada From 2006 to 2010

ObjectiveTreatment of latent TB infection (LTBI) in high-risk populations has been identified as a priority activity for reducing TB incidence. Treatment completion rates are usually far from the 80% target. The objective of this study was to evaluate the proportion of individuals who obtained enough medication for standard LTBI treatment.MethodsUsing the Régie de l’assurance maladie du Québec database, we extracted data on all prescriptions filled as part of the free anti-tuberculosis medication program. We calculated the proportion of patients who had obtained at least 270 doses among patients who had started treatment with isoniazid (INH), and the proportion of patients who had obtained at least 120 doses among patients who had started treatment with rifampin (RMP).ResultsAmong the 2,895 patients who had started INH, 907 (31.3%) obtained at least 270 doses. Among the 373 patients who had started RMP, 242 (64.9%) obtained at least 120 doses. Women were more likely to stop INH treatment before acquiring 270 doses of the medication than men (hazard ratio [HR] = 1.08; 95% confidence interval [CI]: 1.01–1.17).ConclusionOnly 31.3% of patients who started treatment with INH had procured at least 270 doses. Completion rates are far below target values.RésuméObjectifTraiter l’infection tuberculeuse latente (ITL) dans les populations à haut risque représente une activité importante pour réduire le fardeau d’incidence de la tuberculose. Les taux d’achèvement du traitement demeurent en deçà de l’objectif habituel de 80 %. Le but de cette étude était d’évaluer la proportion des personnes qui se sont procuré suffisamment de médicaments pour le traitement de l’ITL.MéthodeÀ partir du fichier de données de la Régie de l’assurance maladie du Québec, nous avons obtenu toutes les ordonnances remplies dans le cadre du Programme de gratuité des médicaments pour la tuberculose. Nous avons calculé, parmi des patients qui ont été traités avec isoniazide (INH), la proportion de ceux qui se sont procuré au moins 270 doses. Nous avons également calculé, parmi des patients qui ont été traités avec rifampine (RMP), la proportion de ceux qui se sont procuré au moins 120 doses.RésultatsParmi les 2 895 patients qui ont été traités avec l’INH, 907 (31,3 %) se sont procuré au moins 270 doses. Parmi les 373 patients qui ont commencé un traitement préventif à la RMP, 242 (64,9 %) se sont procuré au moins 120 doses. Les femmes avaient plus de chances d’abandonner le traitement avant de s’être procuré au moins 270 doses d’INH que les hommes (Ratio de taux [RT] = 1,08; Intervalle de confiance [IC] à 95 %: 1,01–1,17).ConclusionSeulement 31,3 % des patients qui ont été traités avec l’INH se sont procuré au moins 270 doses. Les taux d’achèvement sont bien en deçà des taux habituellement visés.

Mycobacterium tuberculosis transmission over an 11-year period in a low-incidence, urban setting.

SETTING Montreal, Canada, has a mean annual tuberculosis (TB) incidence of 9 per 100,000 population, 1996-2007. OBJECTIVE To characterise potential Mycobacterium tuberculosis transmission by patient subgroups defined by age, sex, birthplace, smear and human immunodeficiency virus status, and to estimate the proportion of cases that resulted from transmission between these patient subgroups. DESIGN Retrospective study using DNA fingerprinting techniques, with clinical and demographic information from the public health department. Among cases with matching fingerprints, a pulmonary index case was identified. The transmission index was defined as the average number of subsequent TB cases generated directly or indirectly from an index case, and was compared among subgroups, including Haitian immigrants. RESULTS Compared to non-Haitian foreign-born index cases, Canadian-born index cases were associated with 2.38 times as many (95%CI 1.24-4.58) subsequent cases, while Haitian-born index cases were associated with 3.58 times as many (95%CI 1.74-7.36). Smear-positive index cases were not independently associated with increased transmission. However, middle-aged Canadian-born index patients were associated with a disproportionate number of subsequent cases. CONCLUSION In Montreal, index patients from several high-risk groups are associated with subsequent transmission. This approach can be applied to other low-incidence settings to identify where targeted interventions could potentially further reduce transmission.

A Case of Active Tuberculosis in a Cabin Crew: The Results of Contact Tracing

INTRODUCTION Transmission of communicable diseases on board aircraft is of considerable concern for passengers and aircrew. Previously published estimates of risk of tuberculosis (TB) transmission have been highly variable. Furthermore, very few studies have been published for active TB in aircrew. METHODS The public health authorities advised the Medical Advisor of an airline that a cabin crewmember had been diagnosed with active TB. Contact tracing was done for the cabin crew who worked with the index case for more than 8 h. Cabin crewmembers were divided in two groups according to their exposure and had one tuberculin skin test (TST) more than 8 wk after the last exposure. Those with a TST > or = 5 mm have been recommended to have a QuantiFERON-TB Gold In-Tube (QFT) assay. RESULTS Among the 56 identified contacts, 32 agreed to be evaluated, of whom 6 (19%) had a TST > or = 5 mm. Of those six, four underwent a QFT with one positive result. None had active TB. The percentages of positives in the two exposure groups were similar. All the positive contacts were born in Canada in the period when the childhood Bacille Calmette-Guérin (BCG) vaccination program was in effect. DISCUSSION The same percentage of positives in the two exposure groups, the proportion of positive contacts below the expected rate in Canadians, and the high proportion of QFT negative among the TST positive contacts suggest that transmission of TB to the cabin crew is unlikely.

Burden of HIV and tuberculosis co-infection in Montreal, Quebec

OBJECTIVE: Define the burden of HIV-TB co-infection and predictors of HIV screening among incident TB cases.METHODS: Analysis of surveillance data on TB incident cases reported to Montreal’s Public Health Department from 2004 to 2009. Among all reported TB cases, proportions of cases with HIV testing and HIV infection were calculated by patient characteristics. A test for linear trends was performed on the annual proportions of HIV-tested and HIV-positive cases. Adjusted odds ratios (AOR) for HIV testing at time of TB diagnosis were computed.RESULTS: A total of 778 incident TB cases were included in the analysis. HIV testing was reported for 50.8% (n=395) of cases. The proportion of HIVtested cases increased significantly from 43% in 2004 to 70% in 2009. HIV-TB co-infection was found in 9.3% of patients with reported HIV status or in 4.2% of the overall cohort. HIV prevalence was high in men, individuals aged 40-59, those originating from Sub-Saharan Africa and the Caribbean, and the homeless. Multivariate analysis revealed that HIV testing at time of TB diagnosis was performed mainly for subjects born in the Caribbean, Central or South America, or Sub-Saharan Africa, those with pulmonary disease, and injection drug users.CONCLUSIONS: Although reporting of HIV testing among incident TB patients increased, targeted HIV testing still occurs. HIV prevalence in TB cases remained stable during the study period; however, it may be underestimated due to missed opportunities for HIV testing and under-reporting.RésuméOBJECTIFS : Estimer le fardeau de la coinfection par le virus de l’immunodéficience humaine (VIH) et la tuberculose (TB) et les facteurs prédictifs du dépistage du VIH chez les cas incidents de TB.MÉTHODES : Les données de surveillance de la TB chez les cas incidents déclarés à la Direction de santé publique de Montréal de 2004 à 2009 ont été analysées. Parmi l’ensemble des cas de TB déclarés, la proportion de cas dépistés pour le VIH et la proportion des cas infectés par le VIH ont été calculées en fonction des caractéristiques des patients. Le test du χ2 pour les tendances linéaires a été utilisé pour évaluer l’évolution des proportions annuelles des cas qui étaient testés et des cas qui étaient séropositifs. Des rapports de cotes pour le dépistage du VIH au moment du diagnostic de la TB ont été calculés après ajustement.RÉSULTATS : Un total de 778 cas de TB ont été inclus aux fins d’analyse. Le résultat du dépistage du VIH était disponible pour 50,8 % (n=395) des cas. La proportion des cas dépistés pour le VIH a augmenté de façon significative passant de 43 % en 2004 à 70 % en 2009. La coinfection VIH-TB était présente chez 9,3 % des patients dont le résultat du dépistage du VIH était disponible ou chez 4,2 % de l’ensemble des patients. La prévalence du VIH était plus élevée chez les personnes de sexe masculin, chez les personnes âgées de 40 à 59 ans, chez les personnes nées en Afrique sub-saharienne et dans les Caraïbes et chez les personnes sans-abri. L’analyse multivariée a montré que le dépistage du VIH au moment du diagnostic de la TB était plus fréquent chez les cas nés dans les Caraïbes, en Amérique centrale ou du Sud et en Afrique subsaharienne, chez les patients atteints de TB pulmonaire et chez les utilisateurs de drogues injectables.CONCLUSION : Bien que le dépistage du VIH parmi les cas incidents de TB augmente, il reste influencé par le profil du patient. La prévalence du VIH parmi les cas de TB est restée stable pendant la période à l’étude; cependant, cette prévalence pourrait être sous-estimée par les occasions de dépister manquées et la sous-déclaration des résultats du dépistage lorsqu’il est fait.

Initial Drug Regimen for Active Tuberculosis Cases in Montreal, 1995-1998

OBJECTIVES To evaluate the proportion of tuberculosis (TB) cases initially treated with the recommended four-drug regimen of isoniazid (INH), rifampin (RIF), pyrazinamide (PZA) and ethambutol (EMB) or streptomycin; and to identify factors associated with the choice of initial therapy. DESIGN Descriptive analysis of surveillance data obtained by TB case notifications from physicians and microbiology laboratories. SETTING The island of Montreal (with a population of 1,854,435 people). STUDY POPULATION All TB cases reported between January 1, 1995 and December 31, 1998. OUTCOME MEASURE The proportion of TB cases initially treated with a four-drug regimen by sex, age, country of birth, site of disease and year of reporting. MAIN RESULTS Seven hundred forty-one cases were reported during the study period. Among the 687 analyzed cases, 406 (59.1%) received the recommended initial four-drug regimen (INH-RIF-PZA-EMB), 187 (27.2%) received an INH-RIF-PZA regimen, 61 (8.9%) received an INH-RIF-EMB regimen and 33 (4.8%) received an INH-RIF regimen only. In a logistical regression model, a four-drug regimen was significantly associated with respiratory disease (odds ratio [OR] 4.48; 95% CI 3.15 to 6.39), age younger than 65 years (OR 2.32; 95% CI 1.55 to 3.45), being foreign-born (OR 1.62; 95% CI 1.06 to 2.48) and later year of reporting (OR 1.27; 95% CI 1.09 to 1.47). CONCLUSIONS The proportion of TB cases initially treated with a four-drug regimen has increased steadily since 1995, reaching 65% in 1998. However, given the rate of INH resistance in Montreal, efforts to promote the use of the initial four-drug regimen must continue.