The longitudinal biomonitoring of residents living near the waste incinerator of Turin: Polycyclic Aromatic Hydrocarbon metabolites after three years from the plant start-up.

The waste-to-energy (WTE) incinerator plant located in the Turin area (Italy) started to recover energy from the combustion of municipal solid waste in 2013. A health surveillance program was implemented to evaluate the potential health effects on the population living near the plant. This program included a longitudinal biomonitoring to evaluate temporal changes of some environmental pollutants, including polycyclic aromatic hydrocarbons (PAHs), in residents living in areas near the Turin incinerator (exposed group, E) compared to those observed in subjects living far from the plant (not exposed group, NE). Ten monohydroxy-PAHs (OH-PAHs), consisting in the principal metabolites of naphthalene, fluorine, phenanthrene, and pyrene, were analyzed in urines collected from the E and NE subjects after one (T1) and three years (T2) of plant activity and compared with those determined in the same cohort established before the plant start-up (T0). Spearman correlation analysis was undertaken to explore possible associations between OH-PAHs and personal characteristics, lifestyle variables, and dietary habits. A linear mixed model (LMM) approach was applied to determine temporal trends of OH-PAHs observed in the E and NE subjects and to evaluate possible differences in trend between the two groups. Temporal trends of OH-PAHs determined by LMM analysis demonstrated that, at all times, the E group had concentrations lower than those assessed in the NE group, all other conditions being equal. Moreover, no increase in OH-PAH concentrations was observed at T1 and T2 either in E or in NE group. Significant positive correlations were found between all OH-PAHs and smoking habits. Regarding variables associated to outdoor PAH exposure, residence near high traffic roads and daily time in traffic road was positively correlated with 1-hydroxynaphthalene and 1-hydroxypyrene, respectively. In conclusion, no impact of the WTE plant on exposure to PAHs was observed on the population living near the plant.

Early childhood vaccination coverage and timeliness by macro-area of origin in children born to foreign women residing in Italy.

OBJECTIVES: Country of origin might affect vaccine uptake in children born to immigrants. We aimed to evaluate differences in childhood vaccination coverage (VC) and timeliness by macro-area of origin of foreign mothers residing in Italy. STUDY DESIGN: Multicentre retrospective birth cohorts. METHODS: We analysed data of 23,287 children born in 2009-2014 to foreign women in the cities of Rome, Turin and Treviso. We retrieved data through record-linkage of the population, vaccination and birth registries. We estimated VCs at different ages for vaccines against tetanus, measles and meningococcal group-C, using the Kaplan-Meier method. Factors associated with vaccine uptake were evaluated using multilevel Poisson models. RESULTS: Estimates of VC at any age and for all antigens were significantly lower in children born to women from Asia and higher in children born to women from Africa, as compared to other macro-areas. Similar differences by area of origin were observed for timeliness; independently of mother's sociodemographic characteristics and neonatal outcomes, the probability of delay vaccination after 2 years of age for each antigen was highest in children born to women from Asia. The risk of missed vaccination for all antigens was significantly higher in children born to younger and unemployed women. CONCLUSIONS: Factors related to area of origin (e.g., cultural habits, language skills) are likely to affect parents' decision to vaccinate their children. These factors, as well as sociodemographic characteristics, should be adequately investigated and addressed to increase vaccine uptake in foreign children, especially those born to Asian women.

Biomonitoring of the adult population living near the waste incinerator of Turin: Serum concentrations of PCDDs, PCDFs, and PCBs after three years from the plant start-up.

In September 2013 a waste-to-energy (WTE) incinerator located in the Turin area (Piedmont, Northern Italy) started to produce energy by the incineration of municipal solid wastes. The plant, one of the largest WTE incinerator in Europe, burns up to 490,000 tons of waste per year. A health surveillance program was implemented in order to evaluate the potential health effects on the population living near the plant. This program included a biomonitoring study aimed at assessing levels of several environmental contaminants including, among others, PCDDs, PCDFs, and PCBs. Before the WTE incinerator start-up (T0), a group of 85 subjects (41 "exposed" and 44 "not exposed" subjects) was randomly selected for enrollment by the local health units among individuals aged 36-50 years who had been living in the same area for at least five years prior to the study. Subjects were balanced by exposure area, sex and five-year age classes. As from the study design, the same cohort was re-evaluated after three years of incinerator activity (T2). A parallel study was conducted on a group of 12 farmers living and/or working in farms located in an area in the range of 5 km around the incinerator. Results of this study did not evidence any impact of the WTE plant on human exposure to PCDDs, PCDFs, and PCBs. In fact, no significant differences were found in the concentrations of PCDDs + PCDFs, DL-PCBs, and NDL-PCBs measured in the population group residing near the plant after three years of activity (T2) with respect to the control group. A significant decrease of serum concentrations of all the analytes was observed at T2 in both groups compared to T0. Serum concentrations of PCDDs, PCDFs, and PCBs in the group of farmers were higher than those observed in the adult population under study.

Tuberculosis incidence in Turin, Italy, 1973-1999.

SETTING: Turin, Italy, 1973-1999. OBJECTIVE: To estimate tuberculosis (TB) incidence rates in Turin between 1973 and 1999. DESIGN: Incidence study. An active search of new TB cases was carried out by examining the clinical records of the three major TB care services in the city. New cases were defined as patients treated for the first time. To evaluate the completeness of this series, data were linked with the TB Notification Register and the Regional Hospital Discharges Register for the years 1997-1999. RESULTS: TB incidence rates declined from 25.6 cases per 100,000 population in 1973 to 6.4 in 1999. TB/human immunodeficiency virus (HIV) co-infection increased after 1985, reaching a peak (16.5%) in 1994-1996, and significantly decreasing in 1997-1999. Foreign-born cases started to increase after 1988, reaching 25.8% of total cases in 1997-1999. TB infections in Italian-born, non-HIV-infected cases occurred mostly among the elderly, while HIV/TB co-infections and TB in immigrants occurred mostly in younger age groups. The study captured 59% of cases diagnosed in Turin in 1997-1999. CONCLUSIONS: In recent years, new cases of TB have been diagnosed mostly among HIV-positive people and immigrants. Preventive and control strategies should focus on these population groups, improving quick identification and effective treatment of cases, and implementing accessible services.

[Inguinal tension-free hernioplasty performed by day-care surgery in a non-specialized hospital]. / Ernioplastica inguinale tension-free praticata in regime di Day Surgery in un ospedale non dedicato.

BACKGROUND: At present, as a result of the introduction of tension-free techniques, the general opinion is that the treatment of inguinal hernia needs day-care surgery. Nevertheless day-care surgery requires a specific organization of the hospital and of the territorial services, after the discharge of the patient. These facilities are not always available all over the country. The aim of this paper is to present the results of the treatment of inguinal hernia performed by day-care surgery in an unspecialized hospital. METHODS: From April 1999 to April 2000, 28 patients (25 M), median age 54 years (range 25-85), affected by inguinal hernia, underwent ernioplasty operation according to Trabucco technique, by only one skilled surgeon, in an unspecialized hospital. Five patients were affected by inguinal hernia of type I of Nyhus, 9 of type II, 10 of type IIIa and 4 of type IIIb. Twenty-five patients underwent spinal anaesthesia and 3 general anaesthesia due to failure of the previous one or for contraindications due to spine diseases or due to patient's request. All patients remained in the hospital the night after the operation. After discharge, patients were controlled in the outpatient ambulatory every other day for 10 days. After that, patients were required to submit to physical examination only if they were symptomatic. At present, average follow-up is of 18.1+/-6.3 months. RESULTS: The following unspecific complications prevalently due to spinal anaesthesia were observed: 2 (7.1%) acute urinary retentions, 1 (3.6%) headache, 1 (3.6%) acute hypotension, 2 (7.1%) feverets, 1 (3.6%) vomiting, and 1 (3.6%) influenza. The specific complications were: 2 (7.1%) transient neuralgias, 2 (7.1%) ecchimosis and 1 (3.6%) infection of the wound. Average intensity of postoperative pain (VAS) was of 2.8+/-1.2. The average abstention from work was of 12.5 days. Until now, any recurrence has been observed. CONCLUSIONS: In spite of the few cases, our results are similar to those of specialized hospitals organized for day-care surgery. Anyway, in the management of these patients in unspecialized hospitals, according to our opinion one night in the hospital after the operation is required for the easiness of the patient and of the surgeon.

Tuberculin reactivity in adult BCG-vaccinated subjects: a cross-sectional study.

INTRODUCTION: Interpretation of the tuberculin skin test (TST) may be complicated by prior bacille Calmette-Guérin (BCG) vaccination. The skin reaction to the vaccination interferes with the management of individuals who may be infected with Mycobacterium tuberculosis. OBJECTIVE: To discriminate between TST reactions due to infection and those due to vaccination in subjects with unknown BCG status. METHODS: Among 60200 subjects tested with 5TU PPD for screening purposes, 4987 contacts of infectious TB cases (Group A), 4962 BCG-vaccinated subjects (Group B) and 5000 subjects from the general population (Group C) were sampled. The frequencies of TST cut-off diameters were calculated for the three groups using a logistic regression model. The frequency of positive subjects in each group and the sensitivity, specificity and predictive values were also computed by means of these cut-offs. RESULTS: The risk of being a contact versus BCG-vaccinated increases 2.43-fold with every mm of TST diameter. The 11 mm cut-off point seems to be the best discriminating value. CONCLUSIONS: Using the traditional 10 mm cut-off, we can consider all vaccinated subjects with a positive TST to be infected. The TST remains a valuable tool for the evaluation of household contacts and suspected cases of tuberculosis in BCG-vaccinated subjects and in populations with high vaccination coverage.

Selection criteria and long-term results of surgery in symptomatic rectocele.

BACKGROUND: The aim of this study was to confirm some selection criteria for the transrectal repair of the anterior rectocele and to compare our surgical results with those reported in the literature. METHODS: From January 1992 to December 1999, 30 females (mean age 52.9 years, range 28-70 yrs) affected by anterior rectocele were prospectively evaluated with a standard questionnaire, clinical examination, proctosigmoidoscopy, colonic transit time, dynamic defecography, anal EMG, anal manometry. Then, they were submitted to transrectal repair of rectocele with anterior plication of the rectal muscular wall. Fourteen (46.6%) of them were also submitted to perineal levatorplasty. Patients were followed postoperatively (mean 25.7 months) with the same standard questionnaire, clinical examination, defecography, and manometry. Results were tested by Fisher's Exact text, Wilcoxon's test, and "t"-test. RESULTS: Rectal dyschezia, incomplete evacuation, digital help in defecating, mean stool frequency, and rectal bleeding significantly improved. After 3 months, 30% of patients had no complaints, 40% had only 1-2 episodes/month complaints, 13.3% had evacuation only using laxatives, and 16.6% were unchanged. Defecography showed a significant reduction of the rectocele in 70% of patients after 3 months. Manometric parameters were not significantly modified. Four (28.6%) out of 14 patients submitted to perineal levatorplasty complained of dyspareunia. CONCLUSIONS: Our surgical results were comparable with those reported in the literature, with more than 80% of successful outcome. Preoperative clinical data and defecography were confirmed to be basic parameters in selecting patients for surgery. Colonic transit time, anal EMG, and anorectal manometry demonstrated to be useful to recognize conditions as slow colonic transit time, peripheral denervation, and reduced voluntary contraction that could lead to a less satisfactory outcome after surgery, and might benefit with a postoperative perineal rehabilitation by biofeedback and anal electrostimulations. The perineal levatorplasty is not suitable in young females, due to the risk of dyspareunia.

Two-year population-based molecular epidemiological study of tuberculosis transmission in the metropolitan area of Milan, Italy.

A 2-year, population-based, molecular epidemiological study was conducted in Milan, Italy, to determine the proportion of tuberculosis (TB) cases attributable to recent transmission. All strains were typed by restriction fragment length polymorphism (RFLP) analysis; clustering was considered indicative of recent transmission. Of the 581 cases, 239 (41.1%) belonged to clusters that consisted of 2 to 11 patients; 28.1% were attributable to recent transmission (number of clustered patients minus 1). Clustering was associated with multidrug-resistant Mycobacterium tuberculosis strains (74.2% of cases), AIDS (60.2%), and a history of incarceration (67.4%). The frequency of multidrug-resistant Mycobacterium tuberculosis was 5.3% overall (15.4% among AIDS patients). Among AIDS patients, infection with a resistant strain was independently associated with clustering (odds ratio, 1.32; 95% confidence interval, 1.07-1.163), while among non-AIDS patients, three factors were associated with clustering: history of incarceration (odds ratio, 2.03; 95% confidence interval, 1.41-2.92), age <30 years (odds ratio, 1.43; 95% confidence interval, 1.05-1.94), and native-born Italian nationality (odds ratio, 1.44; 95% confidence interval, 1.08-1.92). Of the 118 patients who belonged to either the smallest or the largest cluster, 19 (16.1%) reported an epidemiological link with another study patient. The results of this study highlight the need for control programs that focus on selected high-risk groups consisting primarily of HIV-infected individuals and persons with social and lifestyle risks for TB. These programs should be aimed at reducing the probability of transmission of drug-resistant TB through early identification of cases and provision of effective treatment until the individual is cured.

Randomised controlled trial between stapled circumferential mucosectomy and conventional circular hemorrhoidectomy in advanced hemorrhoids with external mucosal prolapse.

BACKGROUND: This randomized prospective study compared the outcome of circular hemorrhoidectomy according to the Hospital Leopold Bellan (HLB) technique (Paris) with Longo stapled circumferential mucosectomy (LSCM) in two homogeneous groups of patients affected by circular fourth-degree hemorrhoids with external mucosal prolapse. METHODS: From December 1996 to December 1999, 80 consecutive patients with fourth-degree hemorrhoids and external mucosal prolapse were randomly assigned to two groups. Forty patients (group A: 18 men, 22 women, mean age 50.5 years, range 21 to 82) underwent HLB hemorrhoidectomy, and 40 patients (group B: 15 men, 25 women, mean age 51.0 years, range 29 to 92) underwent LSCM. Before surgery, all patients were selected with a standard questionnaire for symptom evaluation, full proctological examination, flexible rectosigmoidoscopy, dynamic defecography, and anorectal manometry. No significant differences among the two groups were found. All patients were controlled with follow-up questionnaire and with clinical examination at 1, 2, 4, 12, and 54 weeks after the operation. A postoperative manometry was performed 3 months after surgery. RESULTS: The length of the operation was significantly lower in group B (25 +/- 3.1 SD versus 50 +/- 5.3 minutes, P <0.001). Mean hospital stay was 3 +/- 0.4 days in group A and 2 +/- 0.5 days in group B (P <0.01). Mean duration of inability to work was 8 +/- 0.9 days in group B and 15 +/- 1.4 days in group A (P <0.001). Postoperative pain was significantly lower in group B (P <0.001). Mean length of follow-up was 20 +/- 8.0 months in group A and 20 +/- 7.8 months in group B. Late complications were similar in the two groups, with 0%, at present, recurrence rate. CONCLUSIONS: Our results confirm that both operations are safe, easy to perform, and effective in the treatment of advanced hemorrhoids with external mucosal prolapse. However, the LSCM seems to be preferable owing to the fewer postoperative complications, easier postoperative management, and shorter time to return to work. A longer follow-up is required to confirm the true efficacy of this surgical method.

Effectiveness of infection control measures in controlling a nosocomial outbreak of multidrug-resistant tuberculosis among HIV patients in Italy.

SETTING: Between October 1992 and February 1994, 33 cases of multidrug-resistant tuberculosis (MDR-TB) were diagnosed among patients infected by the human immunodeficiency virus (HIV) and hospitalised in an HIV ward in Milan, Italy. This outbreak was part of a much larger outbreak, begun in another hospital and probably transferred through a patient. OBJECTIVE: To evaluate risk factors for transmission and the effectiveness of infection control measures. DESIGN: 1) Active follow-up of exposed patients, 2) cohort study among HIV-infected patients exposed to MDR-TB cases before and after the implementation of control measures, 3) screening of close contacts of MDR-TB cases, and 4) molecular typing by restriction fragment length polymorphism (RFLP) analysis. RESULTS: The risk of MDR-TB was higher in patients with lower CD4+ lymphocyte percentages and longer duration of exposure. No difference in the daily risk was observed for in-patients vs day-hospital patients or by room distance from an infectious case. Of the 90 patients exposed before the implementation of infection control measures (i.e., October 1992-June 1993) 26 (28.9%) developed MDR-TB, whereas none of the 44 patients exclusively exposed after implementation developed MDR-TB, despite the continuing presence of infectious MDR-TB cases in the ward. CONCLUSION: Simple control measures were effective in significantly reducing nosocomial transmission among patients.

Simple and complicated acute appendicitis. Indications for a correct diagnosis.

BACKGROUND: In this retrospective investigation the symptoms, signs, and laboratory findings collected in 2 groups of patients with simple and complicated acute appendicitis, respectively, have been observed in order to give some indication for a correct diagnosis and surgical treatment. METHODS: A total of 103 consecutive patients affected by simple and complicated acute appendicitis submitted to surgical operation have been studied. RESULTS: Data collected show statistically significant differences between clinical presentation of simple and complicated acute appendicitis. CONCLUSIONS: The conclusion is draws in that anamnesis and clinical examination of the patients affected by acute appendicitis are the best indications for an exact diagnosis and to select patients who need an immediate operation.

Laparotomic vs. laparoscopic rectopexy in complete rectal prolapse.

AIM: The aim of this study was to compare the functional and clinical results of laparotomic and laparoscopic rectopexy in 2 homogeneous groups of patients with complete rectal prolapse and fecal incontinence. METHODS: Between January 1989 and December 1997, twenty-three patients underwent abdominal rectopexy. Thirteen patients (group A, 12 females and 1 male, mean age 57.3, range 22-76 years), and 10 patients (group B, 10 females, mean age 52.3, range 26-70 years) were submitted respectively to either Wells laparotomic or laparoscopic rectopexy by the same surgical team using the same surgical technique and materials. Before the operation a detailed clinical history was collected, and the patients were studied by inspection and digital examination of the anorectum, proctosigmoidoscopy, pancolonic transit time, dynamic defecography, anorectal manometry and anal electromyography. After the operation all patients underwent perineal physiotherapy, external electric stimulation, and perineal biofeedback. Mean follow-up was 37.1 (range 6-90) months in group A and 25.7 (range 6-49) months in group B. Values were compared by chi(2), Mann-Whitney U, and Wilcoxon tests as appropriate. Differences were considered significant at p < 0.05. RESULTS: In both groups dyschezia and fecal incontinence improved significantly (p < 0.05) after the operation. The basal pressure of the anal sphincter, squeezing pressure and rectoanal reflex improved without significance, and anal-perineal pain was not significantly reduced. In group B the postoperative hospital stay was lower than in group A, with a reduction in costs. CONCLUSION: Laparoscopic Wells rectopexy has the same clinical and functional results as laparotomic rectopexy, but with a shorter postoperative hospital stay and lower costs.

The threat of multidrug-resistant tuberculosis: results of 1 yr of surveillance in the Lombardy region of Italy.

A descriptive multicentre study based on laboratory data was carried out in patients with culture-confirmed tuberculosis (TB) who were cared for between September 1995 and August 1996 in 14 general hospitals with at least one human immunodeficiency virus (HIV) ward, a hospital specializing in TB or a large chest clinic, all in the Lombardy region of Italy. For each culture positive for Mycobacterium tuberculosis, the results of susceptibility tests to the five first-line anti-TB drugs were collected; other information collected included: the patient's name, the ward/service where the patient was staying and the characteristics of the culture (biological sample, date of arrival and type of mycobacterium isolated). Foreign-born persons were identified through their names; acquired immune deficiency syndrome (AIDS) patients were identified through record linkage with the National AIDS Registry. Given that only one-quarter of the laboratories performed pyrazinamide-susceptibility tests, resistance to this drug was not analysed. Of the isolates tested, 28.1% were resistant to at least one drug, i.e. single-drug-resistant (SDR) and 12.9% were multidrug-resistant (MDR). The frequency of SDR and MDR strains showed considerable variation by healthcare centre (range 0.0-94.3% and 0.0-37.1%, respectively). In three hospitals, the time of occurrence and the susceptibility pattern of the MDR-TB isolates indicated that clusters of the disease occurred. The frequency of both SDR and MDR strains was significantly higher among AIDS patients (48.8% and 23.6%, respectively) than among foreign-born persons (30.2% and 6.9%) or persons belonging to no known risk group (98.3% and 11.3%). The frequency of drug resistance observed in this study is much higher than that reported in other European surveys and is comparable only to that observed in New York, before the implementation of an effective control programme. Acquired immune deficiency syndrome patients are at very high risk of multidrug-resistant tuberculosis: effective containment and infection control practices should be rigorously implemented to prevent the occurrence of this alarming phenomenon.

[Tuberculosis in Italy: available data and open questions]. / Tubercolosi in Italia: dati disponibili e questioni aperte.

OBJECTIVES: To describe the epidemiological trend of tuberculosis (TB) in Italy. DESIGN: Descriptive study on the basis of routine information sources: TB deaths (1955-1993) and TB notifications (1955-1995). To identify persons with AIDS (PWAs) among notified TB cases, a record linkage with the National AIDS Registry was performed. RESULTS: From 1955 to 1993, the TB mortality constantly decreased by a mean of 7.6% per year. From 1955 to 1995, the crude annual total incidence of TB decreased from 25.26 to 9.12 per 100,000. The trend of decrease of pulmonary TB ceased in 1980, whereas the incidence of extrapulmonary TB began to markedly increase in 1980. Between 1992 and 1995, the average annual meningitis notification rate in children < five years was 0.045 per 100,000. In 1995, the curve of incidence rates by age shows two peaks (> 75 years and 25-34 years). Persons with AIDS and foreigner-born persons represented in total 11.3% of TB cases (1992-1995); in the age class 25-34 years, this proportion was 32.5% (34.1% in 1995). A considerable undernotification of TB among PWAS was detected. CONCLUSION: The TB incidence is no longer decreasing due to the changes of TB case definition in 1987 and the.

Circular hemorrhoidectomy in advanced hemorrhoidal disease.

BACKGROUND/AIMS: Milligan-Morgan's hemorrhoidectomy has a high recurrence rate (> 10%) in patients with circular IV grade hemorrhoids. In such cases a circular hemorrhoidectomy with complete elimination of residual piles, and anoplasty might be more successful. The aim of this retrospective study was to compare the results of circular hemorrhoidectomy using the Hopital Leopold Bellan (HLB) technique (Paris) with the reported results of other techniques in patients with advanced hemorrhoidal disease. METHODOLOGY: From January 87 to December 96, 100 consecutive patients with circular IV grade hemorrhoids underwent radical hemorrhoidectomy. Mean hospital stay was 4 days (range 3-7). Patients were strictly controlled in the postoperative period and in cases of early fibrosis anal dilators were used. RESULTS: Eighty one percent of patients had a complete recovery. The recurrence rate was 4%. The cumulative rate of early and late complications was 34%. Early and late hemorrhages were more frequent than in traditional hemorrhoidectomy, while the incidence of anal stenosis was the same. CONCLUSIONS: The HLB operation is the best choice for patients with advanced circular hemorrhoids because of its radicality and good results. The postoperative morbidity of HLB hemorrhoidectomy is higher than traditional hemorrhoidectomy; nevertheless, all complications are tractable without extension of hospital stay.

Shellfish consumption and awareness of risk of acquiring hepatitis A among Neapolitan families - Italy 1997.

In 1996, about 15% of all reported cases of hepatitis A (n=8651) in Italy were from the Campania region, with Naples reporting the region s highest incidence (34.9/100 000). Almost a half of all cases were between 15 and 24 years of age. In recent years,

A foodborne outbreak of gastroenteritis involving Listeria monocytogenes.

An outbreak of gastroenteritis occurred in Italy among 39 persons who had attended a private supper. All guests were previously healthy, young, non-pregnant adults; 18 (46%) had symptoms, mostly gastrointestinal (78%), with a short incubation period. Four were hospitalized with acute febrile gastroenteritis, two of whom had blood cultures positive for Listeria monocytogenes. No other microorganisms were recovered from the hospitalized patients' specimens. Epidemiological investigation identified rice salad as the most likely vehicle of the food-borne outbreak. L. monocytogenes was isolated from three leftover foods, the kitchen freezer and blender. Isolates from the patients, the foods and the freezer were indistinguishable: serotype 1/2b, same phage type and multilocus enzyme electrophoretic type. Eight (36%) of 22 guests tested were found to have antibodies against L. monocytogenes, compared with none of 11 controls from the general population. This point source outbreak was probably caused by infection with L. monocytogenes. Unusual features included the high attack rate among immunocompetent adults and the predominance of gastrointestinal symptoms.

An outbreak of hepatitis A in Puglia, Italy, 1996.

In the region of Puglia, in the south east of Italy (population: 4 million), the number of notifications of hepatitis A virus (HAV) infection increases in a two yearly cycle. In 1992 a very large outbreak was observed, but no epidemiological investigation

Incubation period of vertically acquired AIDS in Europe before widespread use of prophylactic therapies.

European surveillance data on vertically acquired (VA) AIDS cases were used to investigate the incubation period of AIDS in the absence of widespread prophylactic treatment and to assess the uncertainty associated with parametric estimates based on retrospective data. Nonparametric and parametric analyses, taking into account the effects of data truncation, were based on a total of 792 children diagnosed with AIDS between July, 1982, and June, 1990, inclusive. Among HIV-infected children who develop AIDS within 8 years, the nonparametric estimate of the median age at diagnosis was 34 months. If 20% of children are assumed to develop AIDS by the age of 1 year (a plausible estimate on the basis of published cohort data), the estimated median among all maternally HIV-infected children is 4.4 years, with 26% of children expected to remain AIDS free by 8 years of age. Results from the parametric (double Weibull) model support the hypothesis of a bimodal distribution, with a subgroup of children progressing rapidly to AIDS at a median age of approximately 5 months. However, neither the relative size of this group nor the median age at which AIDS develops in the remaining children can yet be estimated with any reasonable precision.