Louis Pilotto

Health effects of exposure to cyanobacteria (blue–green algae) during recreational water–related activities

Abstract: The aim of this study was to investigate effects on health of exposure to cyanobacteria as a result of recreational water activities. Participants, who were aged six years and over, were interviewed at water recreation sites in South Australia, New South Wales and Victoria on selected Sundays during January and February 1995. Telephone follow–up was conducted two and seven days later to record any subsequent diarrhoea, vomiting, flu–like symptoms, skin rashes, mouth ulcers, fevers and eye or ear irritations. On the Sundays of interview, water samples from the sites were collected for cyanobac–terial cell counts and toxin analysis. There were 852 participants, of whom 75 did not have water contact on the day of interview and were considered unexposed. The 777 who had water contact were considered exposed. No significant differences in overall symptoms were found between the unexposed and exposed after two days. At seven days, there was a significant trend to increasing symptom occurrence with duration of exposure (P = 0.03). There was a significant trend to increasing symptom occurrence with increase in cell count (P = 0.04). Participants exposed to more than 5000 cells per mL for more than one hour had a significantly higher symptom occurrence rate than the unexposed. Symptoms were not correlated with the presence of hepatotoxins. These results suggest symptom occurrence was associated with duration of contact with water containing cyanobacteria, and with cyanobacterial cell density. The findings suggest that the current safety threshold for exposure of 20 000 cells per mL may be too high. (Aust N Z J Public Health 1997; 21: 562–6)

Effect of beta lactam antibiotic use in children on pneumococcal resistance to penicillin: prospective cohort study.

Abstract Objective: To examine the relation between use of antibiotics in a cohort of preschool children and nasal carriage of resistant strains of pneumococcus. Design and participants: Prospective cohort study over two years of 461 children aged under 4 years living in Canberra, Australia. Main outcome measures: Use of drugs, respiratory symptoms, and visits to doctors were documented in a daily diary by parents of the children during 25 months of observation. Isolates of pneumococci, which were cultured from nasal swabs collected approximately six monthly, were tested for antibiotic resistance. Results: From the four swab collections 631 positive pneumococcal isolates from 461 children were found, of which 13.6% were resistant to penicillin. Presence of penicillin resistant pneumococci was significantly associated with childrens use of a β lactam antibiotic in the two months before each swab collection (odds ratio 2.03 (95% confidence interval 1.15 to 3.56, P=0.01)). The odds ratio of the association remained >1 (though did not reach significance at the 0.05 level) for use in the six months before swab collection. The association was seen in children who received only penicillin or only cephalosporin antibiotics in that period. The odds ratio was 4.67 (1.29 to 17.09, P=0.02) in children who had received both types of β lactam in the two months before their nasal swab. The modelled odds of carrying penicillin resistant pneumococcus was 4% higher for each additional day of use of β lactam antibiotics in the six months before swab collection. Conclusions: Reduction in β lactam use could quickly reduce the carriage rates of penicillin resistant pneumococci in early childhood. In view of the propensity of these organisms to be spread among children in the community, the prevalence of penicillin resistant organisms may fall as a consequence. What is already known on this topic Resistance to pneumococcal antibiotics is increasing worldwide One possible cause of resistance is the excessive use of antibiotics in children with respiratory symptoms Few cross sectional studies have looked at the association between antibiotic use and subsequent carriage of organisms resistant to penicillin What this study adds Carriage of pneumococcus is high in preschool Australian children throughout the year and highest in winter The likelihood of carrying penicillin resistant pneumococcus is doubled in children who have used any β lactam antibiotic in the two months before testing The likelihood of a child carrying a penicillin resistant pneumococcus is increased by 4% for each additional day of β lactam use in the six months before testing

Health effects of daily indoor nitrogen dioxide exposure in people with asthma

Household gas appliances produce nitrogen dioxide (NO2), which may be associated with an increase in symptoms in asthmatics. The relationship between indoor NO2 exposure, and respiratory symptoms in people with asthma was evaluated. Self-reported asthmatics (n=125) wore lapel badges that measured NO2 daily over 6 weeks at home. Outdoor pollutants, spores and meteorological parameters were measured daily, in addition to smoking status and demographic factors. Seven asthma symptoms were recorded in diaries, for analysis by same day and also with 1 day lag exposures, using a generalized estimating equation. Significant interactions were demonstrated between NO2 at age < or =14 yrs, with respect to the symptoms of chest tightness on the same day (odds ratio (OR): 1.29, 95% confidence interval (CI): 1.16-1.43) and with a 1 day lag (OR: 1.29, 95% CI: 1.14-1.46), breathlessness on exertion with a 1 day lag (OR: 1.13, 95% CI: 1.00-1.28), daytime asthma attacks on the same day (OR: 1.13, 95% CI: 1.02-1.26) night asthma attacks on the same day (OR: 1.16, 95% CI:1.03-1.30) and with a 1 day lag (OR: 1.15, 95% CI; 1.03-1.29) after adjustment for potential confounders. A significant interaction between NO2 and age 35-49 yrs was demonstrated for coughs with a 1 day lag (OR: 1.15, 95% CI: 1.01-1.31). Daily personal exposures to NO2 are associated with asthmatic symptoms in children.

Tissue Plasminogen Activator −7351C/T Enhancer Polymorphism Is a Risk Factor for Lacunar Stroke

Background and Purpose— Occlusive thrombosis is an important component of small- and large-vessel ischemic stroke. Endogenous tissue plasminogen activator (TPA) is the primary mediator of intravascular fibrinolysis and is predominantly expressed by the endothelium of small vessels. The acute release of TPA is influenced by the TPA −7351C/T polymorphism and therefore may play an important role in the pathogenesis of lacunar stroke. In this study, we investigated the risk of lacunar and nonlacunar ischemic stroke associated with the TPA −7351C/T polymorphism. Methods— We conducted a case-control study of 182 cases of ischemic stroke and 301 community controls. Participants were evaluated for known cerebrovascular risk factors, and the TPA −7351C/T genotype was established by a polymerase chain reaction (PCR) method. Logistic regression was used to determine the risk of lacunar and nonlacunar ischemic stroke associated with the TPA −7351C/T polymorphism. Results— The prevalence of the TPA −7351 CC, CT, and TT genotypes were 46%, 45%, and 9% for controls and 41%, 46%, and 13% for stroke patients, respectively. After adjustment for known cerebrovascular risk factors, the TT genotype was significantly associated with ischemic stroke (OR: 1.9; 95% CI: 1.01 to 3.6). Stratification for stroke subtype showed a significant association between the TT genotype and lacunar stroke but not nonlacunar stroke (OR: 2.7; 95% CI: 1.1 to 6.7). Conclusions— The TPA −7351C/T polymorphism is an independent risk factor for lacunar stroke. The findings suggest that impaired fibrinolysis may play a role in the pathogenesis of lacunar stroke.

Acute skin irritant effects of cyanobacteria (blue-green algae) in healthy volunteers.

Objective: To assess the skin irritant potential of a range of laboratory grown cyanobacterial species using skin‐patch testing on human volunteers.

A cohort study of indoor nitrogen dioxide and house dust mite exposure in asthmatic children

Objective: The purpose of this study was to investigate dose–response relationships between asthma symptoms and indoor nitrogen dioxide (NO2) and house dust mite allergen (HDM) in children. Methods: Asthmatic children from 18 primary schools in Adelaide, Australia, kept a daily symptoms diary over 12 weeks. Home and classroom NO2 levels were measured repeatedly in winter 2000. HDM levels were obtained from beds. Lung function tests were performed at the beginning and at the end of the study period. Results: Data on exposure and respiratory outcomes were gathered for 174 children. For school exposure, the estimated relative symptom rate (RR) for a 10-ppb increase in NO2 for difficulty breathing during the day was 1.09 (95% confidence interval [CI] = 1.03–1.15), at night 1.11 (95% CI = 1.05–1.18), and for chest tightness at night 1.12 (95% CI = 1.07–1.17). Significant symptom rate increases were also found for kitchen NO2 exposure. This was supported by a negative dose–response relationship between percentage predicted forced expiratory volume in 1 second and NO2 (−0.39%; 95% CI = −0.76 to −0.02) for kitchen exposure. Significant threshold effects using a 10-&mgr;g/g cutoff point for HDM exposure were established in the sensitized children for nighttime wheeze (RR = 3.62, 95% CI = 1.49–8.77), daytime cough (RR = 1.64, 95% CI = 1.14–2.36), and daytime asthma attack (RR = 1.95, 95% CI = 1.06–3.60). Conclusion: This study has established reliable risk estimates for exacerbations of asthma symptoms in children based on dose–response investigations of indoor NO2 and HDM.

Trial of nurse-run asthma clinics based in general practice versus usual medical care.

Objective:  The aim of this study was to assess the ability of nurse‐run asthma clinics based in general practice compared with usual medical care to produce at least a moderate improvement in the quality of life of adults with asthma.

Antibiotic resistance in Streptococcus pneumoniae isolated from children.

Objective: To determine the level of antibiotic resistance in pneumoniae (S. pneumoniae) isolated from nasal swabs of healthy children.

Environmental exposure to carcinogens causing lung cancer: Epidemiological evidence from the medical literature

Objective:  In 2000 there were 1.1 million lung or bronchial cancer deaths worldwide, with relatively limited evidence of causation other than for smoking. We aimed to search and appraise the literature regarding evidence for a causal relationship between air pollution and lung cancer according to the 10 Bradford Hill criteria for causality.

Foot Shape and Its Effect on Functioning in Royal Australian Air Force Recruits. Part 1: Prospective Cohort Study

OBJECTIVE To determine whether foot shape (flat, normal, or cavus feet) affects functioning among military recruits. METHODS A total of 230 Royal Australian Air Force recruits embarking on a 10-week basic training course took part in a prospective cohort study of foot shape and its effect on functioning. Recruits were divided into three groups based on their foot shape, i.e., flat feet (n = 22), normal feet (n = 139), and cavus feet (n = 44), with the diagnosis being made from the arch index measured from their footprints. The groups were assessed at baseline and week 8. Outcome measures included pain, injury, foot health, and quality of life. RESULTS There were no significant differences in outcome measures at baseline. At the end of the trial, foot shape was not related to injury. The flat feet group had significantly poorer subjective physical health than did the normal feet group (p = 0.001). CONCLUSION This study provides high-level evidence that foot shape has little impact on pain, injury, and functioning among military recruits.