Miquel Alsedà

Estudio de contactos de enfermos tuberculosos en un área semiurbana

Introduccion Los factores mas importantes en el establecimiento de prioridades para realizar un estudio de contactos son la situacion bacteriologica del paciente y el nivel de exposicion al caso indice. El objetivo del trabajo es analizar los resultados del estudio de contactos de enfermos tuberculosos y su asociacion con la bacteriologia del caso indice y el nivel de exposicion Metodos Se estudiaron los contactos de enfermos tuberculosos que fueron examinados en el Centro de Prevencion y Control de la Tuberculosis (CPCT) de Lleida en el periodo 1991-1997. Para el diagnostico de infeccion tuberculosa se realizo la prueba de Mantoux con 2 UT de derivado proteico purificado RT23 (PPD-RT23). Para diagnosticar la enfermedad tuberculosa se examinaron la situacion clinica, la radiografia de torax y la bacteriologia. Se analizo la asociacion entre la deteccion de infeccion o enfermedad tuberculosa con la bacteriologia del caso indice y el grado de intimidad entre este y el contacto. En el analisis estadistico se realizo la prueba de la chi cuadrado (x2) y se considero significativo un valor de p Resultados La prevalencia de infeccion tuberculosa entre los contactos fue del 44% (763/1.733). Se observo una conversion tuberculinica en el 7,8% de los contactos y se detectaron 31 nuevos casos de tuberculosis (1,8%). La proporcion de infeccion tuberculosa, conversion tuberculinica y deteccion de nuevos casos de tuberculosis fue superior entre los contactos de pacientes con baciloscopia positiva y mayor grado de exposicion. La asociacion de la infeccion tuberculosa con la bacteriologia del caso indice y el grado de exposicion se incremento al restringir el analisis a los contactos menores de 15 anos. La proporcion de casos de tuberculosis detectados entre los contactos convivientes de enfermos con baciloscopia de esputo positiva fue del 4% Conclusiones La investigacion de los contactos de enfermos tuberculosos presenta un elevado rendimiento, incluso entre los contactos de los enfermos de tuberculosis pulmonar con cultivo negativo y entre los contactos de pacientes con tuberculosis extrapulmonar

Smoking in tuberculosis patients increases the risk of infection in their contacts

OBJECTIVE To determine the risk of latent tuberculous infection (LTBI) among contacts of smokers with tuberculosis (TB). METHODS A study was conducted to determine the prevalence of LTBI among contacts of TB cases aged >14 years in Catalonia, Spain. A survey was carried out for each TB case and their contacts. LTBI was diagnosed using the tuberculin skin test (≥5 mm). The risk of LTBI associated with smoking was determined by multi-variate logistic regression analysis, with adjusted odds ratio (aOR) and their 95% confidence intervals (CI). RESULTS The smoking prevalence among TB cases was 40.7% (439/1079). The prevalence of LTBI among their contacts was 29.7% (2281/7673). It was higher among contacts of smoking index cases (35.3%) than among those of non-smokers (25.7%). Smoking was independently associated with an increased risk of LTBI among contacts (aOR 1.5, 95%CI 1.3-1.7), and was estimated to be responsible for 12.8% of infections. CONCLUSIONS Index case smoking increases the risk of LTBI and should be systematically investigated. A reduction in smoking could lower the risk of infection substantially.

Person-to-person transmission of norovirus resulting in an outbreak of acute gastroenteritis at a summer camp.

Background A significant proportion of norovirus (NV) gastroenteritis outbreaks described in the Spanish literature have been because of contaminated food or water. Aim This study describes an outbreak of acute gastroenteritis because of NV in which there was person-to-person transmission. Materials and methods A retrospective cohort study was carried out; we established the case definition for primary and secondary cases. An epidemiological survey was designed, including possible food exposures, and clinical and laboratory data. Water and stool samples were taken from affected individuals and food handlers. The presence of NV was detected using a reverse transcription-PCR assay. We analyzed the risk of gastroenteritis using relative risk and its 95% confidence interval as the measure of association, and estimated the basic reproductive number (R0). Results The primary attack rate was 45.0%, with no significant differences between sexes. The secondary attack rate during the camp stay was 22.7%. The basic reproductive number for 5 days was R0=2.62. The most frequent symptoms were abdominal pain (85.7%) and vomiting (81.9%). Epidemiological analysis showed no association with food or drinking water. A total of 66.6% (8/12) of stool samples tested positive for NV (genogroup II). Conclusion Control measures in general, and hand hygiene in particular, should be extended to the families once the children return home, to prevent secondary cases in NV outbreaks.

Factores asociados a la infección tuberculosa latente en los contactos de pacientes afectados

Background: As tuberculosis control programs have reached acceptable levels in the identification and treatment of persons with active tuberculosis, the next step should be to develop methods of preventing new cases. Persons with latent tuberculosis infection (LTI) are considered to have a higher risk of developing active tuberculosis. The objective of this study was to evaluate the prevalence of LTI and its associated factors in the contacts of tuberculosis patients. Methods: We studied the contacts of tuberculosis patients who were examined in the Center for Tuberculosis Control and Prevention in Lleida (Spain) from 1991-1997. Factors associated with the index case (demographic, radiographic, bacteriologic and therapeutic) and tuberculin skin test results and demographic data in contacts were collected. Data on HIV infection, injection drug use and alcohol consumption in tuberculosis patients were also collected. The associations were assessed by obtaining crude and adjusted odds ratios. Results: The prevalence of LTI among contacts was 36.1% (780/2,161). In the multivariate analysis a higher frequency of LTI was detected in contacts older than 14 years (ORa = 3.34; 95% CI, 2.51-4.45), contacts who had a higher degree of exposure to the index case (ORa = 1.96; 95% CI, 1.59-2.42), contacts of pulmonary tuberculosis patients (ORa = 1.54; 95% CI, 1.01-2.35), contacts of patients with a positive sputum smear (ORa = 1.51; 95% CI, 1.15-1.99), contacts of patients with caverns on chest x-ray (ORa = 1.27; 95% CI, 1.01-1.61) and contacts of patients with delayed treatment (ORa = 1.31; 95% CI, 1.05-1.62). Conclusions: The overall prevalence of LTI in the contacts of patients with tuberculosis was high. Among the factors studied, delayed treatment in the index case was independently associated with the frequency of LTI in tuberculosis contacts. Measures for the early diagnosis and treatment of tuberculosis should be intensified.

BROTES POR NOROVIRUS EN RESIDENCIAS Y CENTROS SANITARIOS DE CATALUÑA

BACKGROUND The low infectious dose and multiple transmission routes favour the appearance of norovirus outbreaks. The objective of this study was to compare the incidence of norovirus outbreaks in hospitals and nursing homes in Catalonia. METHODS A descriptive study of norovirus outbreaks between 15/10/2004 and 30/10/2005 was carried out. An epidemiological survey was completed for each outbreak. Norovirus in clinical samples was determined by PCR techniques. The incidence in each centre and the annual incidence of outbreaks by centre were calculated. Differences were calculated using the chi-square test and the Students t test, taking a p value of > 0.05 as significant. RESULTS Seventeen outbreaks (6 in hospitals and 11 in nursing homes) were detected. The global attack rate was 33.4% (652/1951) and was slightly higher in nursing homes (35.2%) than in hospitals (31.4%). A total of 94.1% (16/17) of outbreaks were caused by person-to-person transmission and only 5.9% (1/17) by foods. The mean number of days between the first and last case was 11.4 (SD = 6.9). The mean duration of symptoms was 2.39 days (SD=1.6), and was higher hospitals, 2.63 (SD=1.7), than in nursing homes, 1.97 (SD=1.7) (p < 0.0001). CONCLUSIONS Norovirus is responsible for a large number of outbreaks due to person-to-person transmission. Control should be standardized to reduce the number and duration of outbreaks.

The case-fatality rate of meningococcal disease in Catalonia, 1990-1997.

The objective was to analyse the case-fatality rate (CFR) of meningococcal disease (MD) in Catalonia, Spain. A retrospective study was carried out. Clinical histories of cases of MD reported for the period 1990–1997 in Catalonia were reviewed. For all cases, the variables gender, age, clinical type, y of presentation, province, phenotype and death by meningococcal disease were collected. The association between death and the other variables was studied by bivariate and unconditional logistic regression analysis. In the 2343 cases studied there were 146 deaths (6.2%) due to meningococcal disease. The CFR was higher in females (OR: 1.5, 95%CI: 1.1–2.1), in the 20 to 49 y (OR: 2.4, 95%CI: 1.2–4.9) and≥50 y (OR: 5.3, 95%CI: 2.8–10.1) age groups, in cases with septicaemia (OR: 2.4, 95%CI: 1.6–3.5), in the cases produced by serogroup A (OR: 4.7, 95%CI: 1.0–23.4) and in cases occurring during 1993 (OR: 2.1, 95%CI: 1.1–4.1) or in the province of Lleida (OR: 2.9, 95%CI: 1.2–7.2). In the multivariate analysis, death was associated with the 20–49 y age group (OR: 3.9, 95% CI: 1.8–8.4), the≥50 y age group (OR: 7.3, 95%CI: 3.6–14.7), septicaemia (OR: 3.1; 95%CI: 2.0–4.7) and residing in the province of Lleida (OR: 3.2; 95%CI: 1.2–8.5). The CFR of meningococcal disease in Catalonia was not associated with the emergent phenotype C:2b:P1.2,5 strain, which caused an outbreak in other regions of Spain.

ToxiInfección alimentaria por ostras causada por virus Norwalk-like

Fundamento El objetivo del estudio fue la investigacion clinica, epidemiologica y microbiologica de un brote de toxiinfeccion alimentaria por el consumo de ostras. Pacientes y metodos Se realizo un estudio de cohortes historicas sobre consumo de 15 alimentosy sintomatologia de los casos. La implicacion de cada alimento se estudio con el riesgo relativoestratificado de Mantel-Haenszel (RRM-H) y su intervalo de confianza (IC) del 95% y seconfirmo mediante el analisis de dosis-respuesta con la prueba de la χ2 de tendencia. Se investigaronlas heces de 5 enfermos y de 2 manipuladores. Resultados La tasa de ataque global fue del 38,0% (19/50). La mediana del periodo de incubacionfue de 39,0 h (maximo de 62 y minimo de 3 h). La proporcion de sintomas fue: fiebre17,6% (3/17), diarrea 57,9% (11/19), vomitos 84,2% (16/19), nauseas 89,5% (17/19) y dolorabdominal 89,5% (17/19). En el analisis estratificado, mientras las ostras mantuvieron su relacion (RRM-H = 3,3; IC del 95%: 1,1-8,7), los caracoles de mar presentaron una reduccion del valor de la RRM-H resultando no significativo (RRM-H = 2,8; IC del 95%: 0,9-41, 1). El consumo de ostras presento una prueba dosis-respuesta estadisticamente significativa (p = 0,005). El examen por microscopia electronica detecto particulas virales de pequeno tamano compatibles con virus Norwalk-like. La implicacion de las ostras se comunico a las autoridades sanitarias. Conclusiones Esta investigacion demuestra la utilidad del analisis dosis-respuesta para aportarevidencias epidemiologicas, la implicacion potencial del consumo de ostras en las toxiinfeccionespor virus Norwalk-like y la necesidad de la investigacion de los centros de produccion parala prevencion y control.

Outbreaks of hepatitis A associated with immigrants travelling to visit friends and relatives

We have read with interest the article by Purcell et al., who reported a cluster of hepatitis A cases in South East England. The investigation of this cluster did not identify any common exposure. In other studies, one of the most frequent reported risk factors is travel to countries with high disease endemicity. Immigrants often make trips that involve close contact with the local population and an increased risk of exposure to different diseases. In the last decade, Catalonia has received a large amount of immigrants from low income countries. Catalonia initiated a program of hepatitis AþB vaccination during 1998e1999 in preadolescents aged 11e12. This program has reduced exposure to the virus and has favoured the accumulation of a susceptible population not covered by the vaccination program. We made a descriptive epidemiological study to characterize index cases of hepatitis A outbreaks in Catalonia in 2001e2012 due to person-to-person transmission and to compare index cases in immigrants and indigenous people. Catalonia is an autonomous community in northwest Spain with a population of 7.5 million. The Statistical Institute of Catalonia (IDESCAT) estimates that 15% of the current population comes from other countries. A hepatitis A outbreak was defined as 2 associated cases with at least one microbiologically confirmed by determination of IgM antibodies. The index case of the outbreak was defined as the first case with onset of symptoms and/or diagnosed (IgM antibodies) and which, according to the epidemiological methods used, most probably began the transmission. In Catalonia, all suspected epidemic outbreaks must be notified to the epidemiological surveillance units (ESU) whose staff confirmed the outbreak and wrote a report on clinical and epidemiological characteristics. Index cases were identified by reviewing reports from each outbreak. Data on the index case was collected by ESU staff using a standardized questionnaire. The variables of the index cases collected were age, sex, country of origin (in the case of children the parents’ country of origin), the setting of the outbreak, visiting family, and men who have sex with men. Factors associated

Factors influencing the spread of pertussis in households: a prospective study, Catalonia and Navarre, Spain, 2012 to 2013

We aimed to investigate transmission rates of pertussis in household contacts of cases and factors associated with transmission. A prospective epidemiological study was conducted in 2012 and 2013 to determine the incidence of pertussis among household contacts of reported cases in Catalonia and Navarre, Spain. An epidemiological survey was completed for each case and contact, who were followed for 28 days to determine the source of infection (primary case) and detect the occurrence of secondary cases. Odds ratios (ORs) were used to estimate the effectiveness of vaccination and chemoprophylaxis in preventing new cases, using the formula (1 − OR) × 100. For the 688 primary cases, a total of 2,852 contacts were recorded. The household transmission rate was 16.1% (459/2,852) and rose according to the age (> 18 years) and lack of immunisation of the primary cases, and also the age (0–18 years), family relationship (siblings and children), lack of vaccination and chemoprophylaxis of contacts. Pertussis vaccine effectiveness in preventing new cases was 65.0% (95% confidence interval (CI): 11.6 to 86.2) for full vaccination (≥ 4 doses) and 59.7% (95% CI: −6.8 to 84.8) for incomplete vaccination (< 4 doses). The effectiveness of chemoprophylaxis was 62.1% (95% CI: 40.3 to 75.9). To reduce household transmission, contacts should be investigated to detect further cases and to administer chemoprophylaxis. The current vaccination status of cases and contacts can reduce household transmission.

Enfermedad meningocÓcica en Cataluña (1990-1997)

Fundamento y objetivo Estudiar el comportamiento de la enfermedad meningococica durante el periodo 1990-1997 e identificar los posibles periodos epidemicos. Material y metodo Se analizaron todos los casos notificados al Sistema de Enfermedades de Declaracion Obligatoria que cumplian los criterios de caso confirmado o sospechoso. Resultados La tasa de incidencia anual fue 4,8/100.000. La tasa de incidencia fue para el serogrupo B de 1,9/100.000 y para el serogrupo C, de 0,8/100.000. La incidencia de la enfermedad presento un ligero descenso en la tendencia durante el periodo estudiado, con un declive anual constante de 0,11 casos/100.000. En el periodo 1996-1997 se observo un aumento estadisticamente significativo de casos por el serogrupo C y en el grupo de edad de 10-19 anos. Conclusiones Globalmente, en el periodo 1990-1997 la incidencia de la enfermedad mostro una tendencia de ligerisima disminucion. No obstante, durante los ultimos 2 anos se observo un aumento de la incidencia, y a ello contribuyo el incremento de casos por el serogrupo C. Este fenomeno se asocio con un desplazamiento en el grupo de 10 a 19 anos, hecho que se ha observado en otros paises coincidiendo con situaciones epidemicas o de mayor actividad del meningococo.