Epidemiology of tuberculosis on Gran Canaria: a 4 year population study using traditional and molecular approaches.

BACKGROUND: In recent years several population based studies using restriction fragment length polymorphism (RFLP) analysis have shown a higher rate of recent transmission of tuberculosis than previously thought. This study was undertaken to determine the transmission patterns of tuberculosis and the potential causes of recent transmission on the island of Gran Canaria (Spain). METHODS: The strains of all patients diagnosed with tuberculosis confirmed by culture between 1 January 1993 and 31 December 1996 were typed by RFLP using the insertion sequence IS6110. A cluster was defined as two or more isolates with an identical RFLP pattern. Epidemiological linkage through contact tracing was investigated. RESULTS: Of the total of 719 patients, 153 (21.3%) were excluded because there was inadequate bacterial DNA for genotyping (n=129) or the isolates of Mycobacterium tuberculosis had less than five copies of IS6110 (n=24). The isolates from 409 patients (72.3%) were grouped into 78 different clusters with an estimated 58.5% of the cases being due to recent transmission. Young age was the only significant predictor of clustering. Only in 147 (35.9%) of the 409 patients belonging to a cluster could an epidemiological link be found. 111 patients (19.6%) were identified as having had previous contact with a tuberculosis patient and 81 of them (72.9%) belonged to a cluster. The three largest clusters included 75, 49 and 20 patients, respectively. CONCLUSION: Recent transmission is frequent among patients with tuberculosis on Gran Canaria and could be associated with certain aspects of control measures. Some of the clusters described in the study could be due to the prevalence of particular strains of M tuberculosis on the island.

[Clinical evaluation of the Amplified Mycobacterium Tuberculosis Direct 2 test]. / Valoración clínica de la prueba Amplified Mycobacterium tuberculosis Direct 2 (AMTD-2, GenProbe) en el diagnóstico rápido de la tuberculosis.

OBJECTIVE: To evaluate the performance of the Amplified Mycobacterium tuberculosis Direct Test 2- Gen Probe (AMTD- 2) for direct detection of Mycobacterium tuberculosis in smear-negative samples. PATIENTS AND METHODS: From January to December 1999, 683 specimens, 333 respiratory and 350 non-respiratory ones collected from 457 patients, were included in the study. All the samples of HIV-positive patients, the respiratory samples from patients suspected of having pulmonary tuberculosis (at least two by patient) and all non-respiratory samples were included. As diagnosis method of reference, the culture isolation was considered. Clinical data were analyzed in case of discrepant results and clinical diagnosis was considered the reference criteria. The technique was performed once a week. RESULTS: The sensitivity, specificity, and positive and negative predictive values of this assay were 58.9%, 93.9%, 37.1% and 97.4% respectively related to the standard culture. When referred to clinical diagnosis of active tuberculosis, these values improved to 70.4%, 97.7%, 73.1% and 96.8% respectively (in respiratory samples were 67.6%, 98.6%, 86.2% and 95.9% and in nonrespiratory ones 76.5%, 96.9%, 56.5% and 98.7% respectively). The mean time of diagnosis by culture and by AMTD-2 were 20.3 days (range 10-63) and 5.7 days (range 2-20) respectively. DISCUSSION: It is concluded that AMTD-2 is a rapid diagnosis method when clinical data are sugestive with active tuberculosis. However, due to the low positive predictive value, it would be convenient to obtain successive samples to confirm the result in patients without clinical evidence of tuberculosis.

[Usefulness of detecting Mycobacterium tuberculosis by genome amplification in the diagnosis of childhood pulmonary tuberculosis]. / Utilidad de la detección de Mycobacterium tuberculosis mediante amplificación genómica en el diagnóstico de la tuberculosis pulmonar en la infancia.

OBJECTIVE: To evaluate the polymerase chain reaction in the diagnosis of pulmonary tuberculosis in children. PATIENTS AND METHODS: 135 samples (68 sputum and 67 gastric aspirates) of 72 patients under 15 years old with suspected tuberculosis and a negative acid-fast stain were included in the study. In all the samples an acid-fast stain and culture in Lowestein-Jensen with and without piruvate were performed. Also, a specific detection of Mycobacterium tuberculosis complex (MT) was made by PCR (Amplicor-MT-Roche Diagnostic). Tuberculosis was certainly diagnosed when M. tuberculosis was isolated or clinical evidence of tuberculosis in positive-PCR cases with negative culture was achieved. RESULTS: Ten samples of six patients were positive culture. Four of these samples were positive PCR. In addition, two samples of two patients with negative culture were positive PCR. Both patients had a clinical diagnosis of pulmonary tuberculosis with effective anti-tuberculosis treatment, one of them had also another positive PCR and culture sample. The results of sensitivity, specificity, positive predictive value and negative predictive value by patient according to the reference methodology were 57.1, 100, 100 and 95.4%, respectively, and by sample 66.6%, 100, 100 and 96.8%, respectively. Other 15 patients presented pulmonary tuberculosis with negative PCR and culture; so the sensitivity of the culture and the PCR regarding a clinical diagnosis were 27.3% (6/22) and 18% (4/22) respectively. CONCLUSION: Due to the diagnosis by culture takes a long time and the low percentage of samples of pediatric patients with positive acid-fast rain stain, the PCR would be useful in order to achieve quickly and specific diagnosis of tuberculosis in a high-prevalence population.

[Epidemiologic study of infection by hepatitis C virus in a hemodialysis unit]. / Estudio epidemiológico de la infección por el virus de la hepatitis C en una Unidad de Hemodiálisis.

OBJECTIVE: To analyze the prevalence of infection, the frequency of HCV genotypes and the epidemiology characteristics among the patients in hemodialysis treatment in one 25 years old hospital hemodialysis center and one 15 years old secondary unit by a transversal cross-section study in 1998. PATIENTS AND METHODS: 171 hemodialyzed-patients were studied. Patients sera were analyzed by the presence of HCV antibodies anti-VHC by a enzymoimmunoassay (Abbott Cientifica) and the presence of antibodies was confirmed by a line immunoassay (Inno-LIA HCV AbIII) and by the presence of VHC-RNA by reverse transcriptase PCR (Cobas Amplicor HCV). Genotypes were determinate by reverse hybridization (Inno-LIA HCV III). RESULTS: Fifty (29.2%) of the patients were HCV antibody positive. Forty-five (26.3%) were HCV-RNA positive, all of them with antibodies positive. The distribution of genotypes was: 1b, 34 (75.5%); 4f, 4 (8.9%); 1a, 3 (6.7%); 1, 3 (6.7%) and 1 case could not be typed (2.2%). In 14 patients (28.0%), seroconversions were documented Twenty-one patients (42.0%) were diagnosed when the routine tests were available and 15 patients (30.0%) were diagnosed pre-dialysis. The multivariate analysis showed that the risk of HCV infection was greater for patients who had been more 8 years on dialysis (OR: 6.22; 95% CI: 1.24-31.07). CONCLUSIONS: Data presented indicate that the prevalence of HCV infections in our hemodialysis units and the number of seroconversions were high and the HCV subtype 1b was more frequent; because of this, the screening by both serological and molecular methods is necessary, at least twice a year, to identify all the infected patients. Besides, we think that is necessary to increase the control of the completion of the Universal Precautions.

[The importance of polymerase chain reaction in the diagnosis of enterovirus infections of the central nervous system in children. Clinico-epidemiologic characteristics]. / Importancia de la reacción en cadena de la polimerasa en el diagnóstico de las infecciones del sistema nervioso central por Enterovirus en la población pediátrica. Características clinicoepidemiológicas.

BACKGROUND: To compare the diagnosis utility of a reverse transcription-polymerase chain reaction (RT-PCR) for detection of enteroviral RNA in cerebrospinal fluid (CSF) in comparison to viral culture for central nervous system infections in pediatric population and to know the clinic epidemiological characteristics of this infection. METHODS: From June to December of 1997, 116 CSF samples of children were included in the study. The samples were inoculated in MRC-5 and HEP-2 and the enterovirus RNA was detected with AMPLICOR-Enterovirus (Roche Diagnostic System). The virus were typed by neutralization. RESULTS: 36 samples were positive (30 were positive for RT-PCR and 6 for RT-PCR and viral culture). The media time in detect the CPE was 4.8 days. The viruses found were four echovirus 6, one echovirus 30 and one echovirus 7. Fifteen children were under 6 months (93.3% under two months) and 21 children over 6 months with a media age of 81 months (range, 38-160 months). In over 6 months old children, the most frequent clinical presentation was meningitis aseptic syndrome with pleocytosis and in under 6 months old ones was fever and only 60% of these children had pleocytosis. The evolution was good in all the cases. CONCLUSIONS: AMPLICOR-Enterovirus is a sensitive method for the diagnosis of enteroviral meningitis. The clinical manifestations are different with the age and due to the absence of neurological symptoms and pleocytosis in the patients under two months, we think that it is necessary to study the presence of enterovirus with genetic amplification methods in this population of patients.

[Outbreak of schistosomiasis in a group a travellers returning from Burkina Faso]. / Brote de esquistosomiasis en un grupo de viajeros procedentes de Burkina Fasso.

BACKGROUND: Schistosomiasis in Spain is always an imported disease mainly presented in travellers from endemic areas with a history of having bathed in fresh water and in immigrants from these areas. A group of travellers presenting infection by schistosomes following an 8-day journey to Burkina Faso. PATIENTS AND METHODS: The travellers, residents of Gran Canaria (Spain), who had bathed in fresh water were studied by schistosomiasis serology and parasitologic examination in stools and urine. RESULTS: A total of 29 travellers were studied, 20 (69%) of whom were considered to be infected, on presenting positive serology and/or coproparasitologic examination. Fourteen of the infected patients presented clinical symptomatology compatible with the Katayama syndrome, while 6 were asymptomatic. The mean time to appearance of the symptoms was 27 days and these were most frequently fever, headache, neck pain, diarrhea and arthromyalgia together with eosinophilia achieving a mean value of 3,513 eosinophils/microliter. All the infected travellers presented positive serology and in 5 eggs of a Schistosoma mansoni were observed in stools. All the infected patients were treated with praziquantel. CONCLUSIONS: Limited exposure by bathing in fresh water in this group of travellers led to a high rate of infection. The diagnosis of schistosomiasis should be considered in any traveller from an endemic area with a history of having bathed in fresh water. In the case of an outbreak, investigation of all the travellers who had bathed is recommendable given that the infection may be asymptomatic.

[The experience of the search for Lyme disease in the eastern Canary Islands]. / Experiencia en las Islas Canarias orientales en la búsqueda de la enfermedad de Lyme.

BACKGROUND: The eastern region of Canary Islands presents certain climatic and atmospheric conditions which differentiate it from the accepted parameters in cases of Lyme disease. We present a serologic study of patients with clinical syndrome which is potentially compatible with Lyme disease, in an effort to clarify the presence of this disorder region. MATERIAL AND METHODS: We assayed type IgG and IgM antibodies against the flagellin antigen of the native Borrelia burgdorferii using indirect enzymeimmunoassay (EIA) as a screening technique. In the serum presenting positive screening we confirmed this result with immunoblot (IB) type IgG and/or IgM with synthetic peptides for the antigenic epitopes p14, p41, p100, OspA and OspC. We review the clinical history of the patients with reactive sera. RESULTS: We studied a sample group of 1,452 patients considered clinically compatible with Lyme disease over a 42-months period, presenting the screening results for serologic positive 47 (3.2%). From this sample, 24 (1.65%) were IB reactive, independent of the type of immunoglobulin. Only two fulfilled the criteria of both IB-IgM positive, one with antibodies against OspC and p41 proteins finally diagnosed as arteriosclerotic encephalopathy suboccipital Binswanger and another with antibodies against p100 and p41 proteins, diagnosed as presenting a primary cytomegalovirus disease. The bands that, most often lead to reactive IB were p41 and p14. Of the 24 patients who presented reactive IB, 14 (58.3%) also presented other previous data wich produced the false positives, 8 with autoimmune disease, 5 viral infectious and one infection due to Treponema pallidum. CONCLUSION: Due to the lack of studies carried out in this field which would verify or rule out an epidemiologic chain in our region, our serologic and clinical data put the eastern Canary Islands in doubt as an endemic area of Lyme disease.

[Usefulness of determining low-avidity IgG antibodies in the diagnosis of primary rubella infection in pregnant women]. / Utilidad de la determinación de anticuerpos IgG de baja avidez en el diagnóstico de la primoinfección por rubéola en la mujer embarazada.

BACKGROUND: It is necessary to have an easy and quickly test to distinguish "false positive" rubella IgM results and residual antibodies from the antibodies produced in the primary infection, in pregnant women. The avidity of IgG antibodies test seems to differentiate between primary rubella infection and past infections, reinfections or postvaccination, showing its utility in the diagnosis of primary infection in other infectious diseases. METHOD: For 30 months, 178 sera from 157 patients with clinical and/or epidemiological rubella suspicion or with a positive rubella IgM result as result of an accidental serological finding, were remitted to our laboratory for a serological follow up. We distinguished 3 patient groups: outbreak group, 112; pregnant women, 36, and newborn 11. Rubella IgM antibodies by indirect EIA previous the rheumatoid factor absorption; IgG antibodies of low avidity by indirect EIA previous treatment of serum with 6 M urea, were detected in the sera. It considered a positive result, a rubella avidity index (AI) < 50%. RESULTS: In the epidemic outbreak group, 90.2% of the patients were not vaccinated. 80% of cases occurred in young men between 14 an 20 years old. From 109 patients (97.3%) with rubella IgG antibodies, 92 (84.4%) showed AI-IgG lower than 50%. In this group, the mean rate of AI-IgG rubella was 29.0%. In the pregnant women group, except for two of them, rubella IgM antibodies were an accidental finding in a serological pregnancy screening. Thirty patients (83.8%) showed AI-IgG rubella > 50%. The two pregnant women who had evidence of clinical and epidemiological rubella showed AI-IgG rubella of 37.4% and 20.9%. Another four pregnant women showed AI-IgG rubella close to cut-off (44.7-49.0%). The mean AI-IgG rubella in this group was 71.8%. The mean AI-IgG Rubella between the epidemic outbreak group and the pregnant women group, 29.0 and 71.8% respectively, was statistical significance (p < 0.001). CONCLUSIONS: The avidity IgG test is simple and quickly, and it allow to exclude most of positive results because of residual IgM antibodies and false reactive.

[Prevalence of hepatitis C virus genotypes: epidemiology and histologic characteristics]. / Prevalencia de genotipos del virus de la hepatitis C: epidemiología y características histológicas.

OBJECTIVE: To analyse the prevalence of HCV genotypes among patients from Gran Canaria and the relation with the routes of viral transmission, date of primoinfection and severity of hepatic lesion. PATIENTS AND METHODS: 179 patients were studied. In 61 patients the date of exposure was determinate. Liver biopsies were obtained in 139 patients. Genotypes were determinate by reverse hybridisation using InnoLiPA genotyping kit (Innogenetics). RESULTS: The distribution of genotypes was: 1b, 114 (63.7%), 1a, 30 (16.7%); 1, 17 (9.5%); 3a, 7 (3.9%); 4c/4d, 6 (3.3%); 2, 1 (0.5%); 2a/2c, 2 (1.1%), 3, 1 (0.5%) and 4f, 1 (0.5%). We did not find any case of coinfection with a second genotype. In univariable analysis, we found statistically differences in sex (78.9% of women infected with genotype 1b compared with 55.1% of men, p < 0.01 and 31.6% of men infected with 1a, 3a and 4c/4d compared with 15.7% of women, p < 0.01) and age (median age in genotype 1b 45 +/- 12 years vs 36 +/- 9 years in the other genotypes, p < 0.01). HCV subtypes 1a and 3a were predominant in patients IVDA (47.6% and 23.85% respectively) and 1b in blood transfusion receptors (71.2%) (p < 0.01). In 40.2% of the patients, the sources of infection were unknown. In the multivariable logistical regression analysis we found the only factor influencing the genotypes distribution was the transmission mechanism (p < 0.001) and sex and age are relationated with the transmission mode. The media infection duration in patients infected with 1b was 22 +/- 11 years vs 9 +/- 6 years in the other genotypes. We found differences in the liver histologic findings and the age of the patient, but not in the different genotypes. CONCLUSIONS: Our study reflects the higher frequency of HCV subtype 1b in our area and a different prevalence of genotypes in relation to mode of transmission. Our results suggest that in our media the liver damage seems to be directly influenced by the age of the patient, but not influenced by HCV genotype.

[Performance of the IgG avidity test in patients with cytomegalovirus disease]. / Comportamiento del test de avidez de IgG en pacientes con enfermedad por citomegalovirus.

BACKGROUND: IgG antibodies produced early in infection has a low avidity to their respective epitopes, so that an assay to detect those antibodies could be easily used to diagnose a recent primary infection. A prospective study of anti-CMV IgG avidity test in patients with microbiological evidence of active CMV infection was made. METHODS: One hundred thirty-five patients were studied. All patients sera were tested for CMV antibodies "pool" IgG/IgM, IgM and antibody IgG avidity index (AI). Furthermore, samples of blood leucocytes from immunosuppressed patients to detect CMV viremia by conventional and shell-vial cell culture isolation and to detect CMV antigenemia, were processed. The avidity index IgG-CMV (AI IgG-CMV) less than 60% was defined as a positive result. CMV infection and disease were defined. RESULTS: The avidity index was < 60% in 16.3% of all patients and in 68.7% of patients with CMV disease. AI IgG-CMV was positive in 81.8% of patients with primary CMV disease and 9.1% with secondary CMV disease. The mean avidity index reading was 35% in primary CMV disease, 88.3% in secondary CMV disease (p < 0.001) and 87.9% in infected patients without CMV disease criterion (p < 0.001). The sensitivity, specificity, VPP and VPN of avidity index IgG-CMV were 85.7%, 97.4%, 75.0% and 94.9% respectively, in primary CMV disease diagnostic respect to all patients with microbiological evidence of active CMV infection. CONCLUSIONS: Avidity index IgG-CMV seems to be a good serological test to diagnose primary CMV disease with only one serum, probably with independence of patients immune state.

[Clinical characteristics and epidemiologic study of a listeriosis outbreak in Grand Canary]. / Características clínicas y estudio epidemiológico de un brote de listeriosis en Gran Canaria.

BACKGROUND AND METHODS: Human infections caused by Listeria monocytogenes often present as sporadic cases without any epidemiological relationship among them; however they also appear as outbreaks that are usually detected by an increase in the number of cases diagnosed by hospitals of the geographic area. Between December 1991 and May 1993, twenty four cases of listeriosis were detected in three hospitals of Las Palmas de Gran Canaria; and they were classified as an outbreak. Our report describes its clinical, epidemiological and microbiological aspects. RESULTS AND CONCLUSIONS: Twenty four cases of listeriosis were diagnosed, 12 occurred in pregnant women or neonates (5 and 7 respectively) and 12 in non pregnant adults. All adult infections were community-acquired. The incidence rate was, for the epidemic area, 76.3 cases per million population during the period considered (18 months). Among non pregnant adults, 9/12 patients had some underlying disease and 9/12 presented CNS affection (meningitis and/or cerebritis). In the group of pregnant women, 4 cases occurred in the second trimester and fetal loss was caused; one case was detected in the third trimester and four weeks later the patient delivered an unaffected infant. All cases of neonatal listeriosis presented as early-onset sepsis. Of the 24 strains of L. monocytogenes, 21 were serotype 4, two were serotype 1 and one was not typeable. Strains from 12 patients were available for epidemiological analysis, seven of which corresponded to the same pattern and there were three more different patterns.

[Microbiological study of vulvovaginitis in premenarcheal girls]. / Estudio microbiológico de vulvovaginitis en niñas prepúberes.

BACKGROUND: A prospective microbiological study of the vaginal swab specimens from premenarcheal girls with clinical diagnosis of vulvovaginitis was done from the 1st of September 1991 to the 31st of August 1994. PATIENTS AND METHODS: Vaginal secretions from premenarcheal girls with clinical findings were examined. Most important pathogenic agents were investigated and if there was an inflammatory reaction in the Gram stain and a heavy growth on culture, other potentially pathogenic agents were considered also. RESULTS: In 70 (28.7%) of the 262 patients a potentially pathogenic microorganism was found: eight cases (3.0%) due to Streptococcus pyogenes, four cases (1.5%) due to Candida albicans. Only in one case Neisseria gonorrhoeae was isolated. Among the uncertain etiologic agents, Haemophilus influenzae was the most frequently isolated (7.6%). In 25 (12.6%) of the 198 patients Enterobius vermicularis ova were visualized. CONCLUSIONS: Streptococcus pyogenes was the most frequently related organism with the vulvovaginitis syndrome among the traditionally established pathogens. The role of Haemophilus influenzae should be considered due to the high prevalence of isolation in this group of patients. We consider that differential diagnosis with Enterobius vermicularis infestation should be done in all cases.

[Comparative study of the serologic response of IgA and IgM type in the diagnosis of acute toxoplasmosis]. / Estudio comparativo de la respuesta serológica del tipo IgA e IgM en el diagnóstico de la toxoplasmosis aguda.

BACKGROUND: IgM serologic response in the diagnosis of acute toxoplasmosis presents interpretation problems. A comparative study with IgA detection of antibodies was performed. METHODS: A parallel serologic study was carried out with IgM and IgA enzymoimmunoassay enhancement techniques in the sera of patients suspected of having toxoplasmosis. RESULTS: Positive results for IgM and/or IgA were presented in 74 sera (47 patients): 86.3% for the former and 58.9% for the latter (p < 0.001). The group of IgA-/IgA+ sera presented a low mean of proportionality index (PI): 1.6 versus the IgM+ sera group in the context of IgG seroconversion with a PI of 3.4 (p < 0.001). Out of the 9 patients with demonstrated IgG, all were IgA+ and seven IgM+. CONCLUSIONS: The present data seem to support greater specificity of the determination of IgA antibodies than that of IgM in the diagnosis of acute toxoplasmosis.