Increased rainfall is associated with increased risk for legionellosis

Legionnaires' disease (LD) is caused by Legionella species, most of which live in water. The Mid-Atlantic region experienced a sharp rise in LD in 2003 coinciding with a period of record-breaking rainfall. To investigate a possible relationship, we analysed the association between monthly legionellosis incidence and monthly rainfall totals from January 1990 to December 2003 in five Mid-Atlantic states. Using negative binomial model a 1-cm increase in rainfall was associated with a 2.6% (RR 1.026, 95% CI 1.012-1.040) increase in legionellosis incidence. The average monthly rainfall from May to September 1990-2002 was 10.4 cm compared to 15.7 cm from May to September 2003. This change in rainfall corresponds to an increased risk for legionellosis of approximately 14.6% (RR 1.146, 95% CI 1.067-1.231). Legionellosis incidence increased during periods of increased rainfall; identification of mechanisms that increase exposure and transmission of Legionella during rainfall might lead to opportunities for prevention.

Outbreak of Legionnaires' disease associated with a display whirlpool spa

BACKGROUND

Recognized outbreaks of Legionnaires' disease (LD) are rare; when they occur, they provide opportunities to understand the epidemiology of the illness and improve prevention strategies. We investigated a population-based outbreak.

METHODS

After the confirmation of LD in October 1996 in five people in neighbouring towns in southwest Virginia, active surveillance for additional cases was undertaken. A case-control study was conducted to identify exposures associated with illness, followed by a cohort study among employees of the facility at which the source of the outbreak was located in order to assess unrecognized exposure and illness. Samples of likely sources of LD in the facility were cultured for LEGIONELLA:

RESULTS

In all, 23 laboratory-confirmed cases of LD were eventually identified. Of the 15 cases in the case-control study, 14 (93%) reported visiting a home-improvement store, compared with 12 (27%) of 45 controls (matched odds ratio [MOR] = 23.3; 95% CI : 3-182). Among home-improvement centre patrons, 10 (77%) of 13 cases questioned recalled either visiting or walking by a display whirlpool spa, compared with 3 (25%) of 12 controls (MOR = 5.5; 95% CI : 0.7-256.0). Two cases' sputum isolates were an exact match, by monoclonal antibody subtyping and arbitrarily primed polymerase chain reaction, to a whirlpool spa filter isolate from the store. Employees reporting more exposure to the display spas were more likely to report symptoms of LD or to have an elevated titre.

CONCLUSIONS

This investigation shows that LD can be transmitted from a whirlpool spa used for display only, and highlights the need for minimizing the risk of transmission of LD from all water-filled spas. Key messages This paper describes an investigation of a population-based outbreak of Legionnaires' disease (LD). A case-control study first identified a home-improvement store as the likely source of the outbreak. An environmental investigation later confirmed that finding, as two cases' sputum isolates were an exact match, by monoclonal antibody subtyping and arbitrarily primed polymerase chain reaction, to a whirlpool spa filter isolate from the store. The spa was intended and used for display only.

High dose rate (HDR) brachytherapy technique: for carcinoma of uterine cervix using Nucletron applicators

This study describes our existing treatment method for high dose rate (HDR) brachytherapy of carcinoma of uterine cervix using Nucletron applicators. Based on our clinical experience with low dose rate (LDR) brachytherapy since 1986, we deliver 40-45Gy by external and 30Gy by internal radiation therapy. The change in regimen using HDR brachytherapy is that internal radiation dose is given in 5 fractions at weekly intervals following external radiotherapy. We have analyzed the dosimetry of 20 patients; total of 100 treatments done at our center using ring-tandem (R-T) and ovoid-tandem (O-T) applicator combinations. Since O-T applicator has more flexibility of using desired tandem length and reduced rectum and bladder dose due to internal shielding inside the ovoids, we have made the transition from R-T to O-T combination of applicator. The dose volume histogram of the isodose curve indicates that there is an increase in isodose volume with the O-T applicator by as much as 1.5 times as compared to R-T applicator. In majority of the treatments, rectum and bladder doses are less than 70% of target dose, however in very few treatments, the bladder dose has increased to more than the target dose, in which case, the applicators were reseated and added more packing or reduced the dose per fraction, for better tolerance of late responding normal tissues. All our dose calculations are checked with an independent calculation method and agreement was obtained with in 5-7% discrepancy.(ABSTRACT TRUNCATED AT 250 WORDS)