Caroline C. Johnson

It’s Not the Heat, It’s the Humidity: Wet Weather Increases Legionellosis Risk in the Greater Philadelphia Metropolitan Area

BACKGROUND Legionella species are abundant in the environment and are increasingly recognized as a cause of severe pneumonia. Increases in cases of community-acquired legionellosis in the greater Philadelphia metropolitan area (GPMA) led to concern that changing environmental factors could influence occurrence of disease. METHODS We evaluated the association between weather patterns and occurrence of legionellosis in the GPMA, using both traditional Poisson regression analysis and a case-crossover study approach. The latter approach controls for seasonal factors that could confound the relationship between weather and occurrence of disease and permits the identification of acute weather patterns associated with disease. RESULTS A total of 240 cases of legionellosis were reported between 1995 and 2003. Cases occurred with striking summertime seasonality. Occurrence of cases was associated with monthly average temperature (incidence rate ratio [IRR] per degree Celsius, 1.07 [95% confidence interval [CI], 1.05-1.09]) and relative humidity (IRR per 1% increase in relative humidity, 1.09 [95% CI, 1.06-1.12]) by Poisson regression analysis. However, case-crossover analysis identified an acute association with precipitation (odds ratio [OR], 2.48 [95% CI, 1.30-3.12]) and increased humidity (OR per 1% increase in relative humidity, 1.08 [95% CI, 1.05-1.11]) 6-10 days before occurrence of cases. A significant dose-response relationship for occurrence of cases was seen with both precipitation and increased humidity. CONCLUSIONS Although, in the GPMA, legionellosis occurred predominantly during summertime, the acute occurrence of disease is best predicted by wet, humid weather. This finding is consistent with the current understanding of the ecological profile of this pathogen and supports the contention that sporadic legionellosis occurs through contamination of water sources.

Peritonitis: Update on Pathophysiology, Clinical Manifestations, and Management

by directly traversing the intact intestinal wall. In an animal Although primary peritonitis may occur in children without model, Escherichia coli passes from the bowel into the peritopredisposing disease, it is especially associated with post- neal cavity after the introduction of hypertonic solutions into necrotic cirrhosis and nephrotic syndrome. In adults, primary the peritoneum. The infrequent occurrence of bacteremia and peritonitis develops in up to 25% of patients with alcoholic the multiplicity of species in peritoneal fluid when anaerobic cirrhosis but has also been reported to occur in adults with bacteria are involved suggest that transmural migration of bacpostnecrotic cirrhosis, chronic active hepatitis, acute viral hepa- teria is the probable route of infection of ascitic fluid in most of these patients. In prepubertal girls, the pathogenesis of primary peritonitis is likely related to an ascending infection of genital origin, as

Let the sun shine in: effects of ultraviolet radiation on invasive pneumococcal disease risk in Philadelphia, Pennsylvania.

BackgroundStreptococcus pneumoniae is a common cause of community acquired pneumonia and bacteremia. Excess wintertime mortality related to pneumonia has been noted for over a century, but the seasonality of invasive pneumococcal disease (IPD) has been described relatively recently and is poorly understood. Improved understanding of environmental influence on disease seasonality has taken on new urgency due to global climate change.MethodsWe evaluated 602 cases of IPD reported in Philadelphia County, Pennsylvania, from 2002 to 2007. Poisson regression models incorporating seasonal smoothers were used to identify associations between weekly weather patterns and case counts. Associations between acute (day-to-day) environmental fluctuations and IPD occurrence were evaluated using a case-crossover approach. Effect modification across age and sex strata was explored, and meta-regression models were created using stratum-specific estimates for effect.ResultsIPD incidence was greatest in the wintertime, and spectral decomposition revealed a peak at 51.0 weeks, consistent with annual periodicity. After adjustment for seasonality, yearly increases in reporting, and temperature, weekly incidence was found to be associated with clear-sky UV index (IRR per unit increase in index: 0.70 [95% CI 0.54-0.91]). The effect of UV index was highest among young strata and decreased with age. At shorter time scales, only an association with increases in ambient sulphur oxides was linked to disease risk (OR for highest tertile of exposure 0.75, 95% CI 0.60 to 0.93).ConclusionWe confirmed the wintertime predominance of IPD in a major urban center. The major predictor of IPD in Philadelphia is extended periods of low UV radiation, which may explain observed wintertime seasonality. The mechanism of action of diminished light exposure on disease occurrence may be due to direct effects on pathogen survival or host immune function via altered 1,25-(OH)2-vitamin-D metabolism. These findings may suggest less diminution in future IPD risk with climate change than would be expected if wintertime seasonality was driven by temperature.

The continuum of hepatitis C testing and care

A hepatitis C virus (HCV)‐infected person will ideally have access to quality health care and move through the HCV continuum of care (CoC) from HCV antibody (Ab) screening, HCV‐RNA confirmation, engagement and retention in medical care, and treatment. Unfortunately, studies show that many patients do not progress through this continuum. Because these studies may not be generalizable, we assessed the HCV CoC in Philadelphia from January 2010 to December 2013 at the population level. The expected HCV seroprevalence in Philadelphia during 2010‐2013 was calculated by applying National Health and Nutrition Examination Survey prevalences to age‐specific census data approximations and published estimates of homeless and incarcerated populations. HCV laboratory results reported to the Philadelphia Department of Public Health and enhanced surveillance data were used to determine where individuals fell on the continuum. HCV CoC was defined as follows: stage 1: HCV Ab screening; stage 2: HCV Ab and RNA testing; stage 3: RNA confirmation and continuing care; and stage 4: RNA confirmation, care, and HCV treatment. Of approximately 1,584,848 Philadelphia residents, 47,207 (2.9%) were estimated to have HCV. Positive HCV results were received for 13,596 individuals, of whom 6,383 (47%) had a positive HCV‐RNA test. Of these, 1,745 (27%) were in care and 956 (15%) had or were currently receiving treatment. Conclusion: This continuum provides a real‐life snapshot of how this disease is being managed in a major U.S. urban center. Many patients are lost at each stage, highlighting the need to raise awareness among health care professionals and at‐risk populations about appropriate hepatitis testing, referral, support, and care. (Hepatology 2015;61:783–789)

Failure to Test and Identify Perinatally Infected Children Born to Hepatitis C Virus–Infected Women

BACKGROUND Vertical transmission of hepatitis C virus (HCV) is the most common route of pediatric HCV infection. Approximately 5% of children born to HCV-infected mothers develop chronic infection. Recommendations employ risk-based HCV testing of pregnant women, and screening children at a young age. This study assesses testing rates of children born to mothers tested HCV-positive in a major US city with a high burden of HCV infection. METHODS HCV surveillance data reported to the Philadelphia Department of Public Health are housed in the Hepatitis Registry. Additional tests, including negative results, were retrospectively collected. HCV data were matched with 2011-2013 birth certificates of children aged ≥20 months to identify mothers tested HCV-positive and screened children. The observed perinatal HCV seropositivity rate was compared to the expected rate (5%). RESULTS A total of 8119 females aged 12-54 years tested HCV-positive and in the Hepatitis Registry. Of these, 500 (5%) had delivered ≥1 child, accounting for 537 (1%) of the 55 623 children born in Philadelphia during the study period. Eighty-four (16%) of these children had HCV testing; 4 (1% of the total) were confirmed cases. Twenty-three additional children are expected to have chronic HCV infection, but were not identified by 20 months of age. CONCLUSIONS These findings illustrate that a significant number of women giving birth in Philadelphia test positive for HCV and that most of their at-risk children remain untested. To successfully identify all HCV-infected children and integrate them into HCV-specific care, practices for HCV screening of pregnant women and their children should be improved.

Association between enhanced screening for Chlamydia trachomatis and Neisseria gonorrhoeae and reductions in sequelae among women.

PURPOSE Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (GC) are typically asymptomatic, but, if untreated, can lead to sequelae including pelvic inflammatory disease (PID) and ectopic pregnancy. The objective was to describe trends of these sequelae in Philadelphia after implementing citywide screening in a high-morbidity population (>6% positivity). METHODS In this ecologic study, which used data from 1996 to 2007, multivariable linear regression analysis was used to assess the association between the number of annual CT/GC screening tests by gender and the number of women aged 14-30 years hospitalized for PID or ectopic pregnancy. A standardized hospitalization database provided the number of admissions with a discharge diagnosis of PID or ectopic pregnancy. Positive CT/GC laboratory results reported by hospitals and emergency departments (EDs) were used as a proxy for outpatient PID. RESULTS Between 1996 and 2007, CT/GC screening increased by 188%, whereas declines were noted in hospitalized PID cases (36%, -173 cases), ectopic pregnancy (38%, -119 cases), and ED-diagnosed CT/GC cases (39%, -727 cases). Screening 10,000 females for CT/GC corresponded with 26.1 fewer hospitalized PID cases (95% confidence interval 11.2-41.1), whereas screening 10,000 males corresponded to 10.4 (95% CI: 2.6-18.2) fewer cases. Although male screening was not significantly associated with ectopic pregnancy, screening 10,000 females was associated with 28.6 fewer ectopic pregnancies (95% CI: 7.4-49.8). CONCLUSIONS This ecologic analysis found a correlation between large-scale CT/GC screening in a high-morbidity population and reductions in hospitalized PID, ectopic pregnancies, and ED-diagnosed CT/GC.

Environmental Exposures and Invasive Meningococcal Disease: An Evaluation of Effects on Varying Time Scales

Invasive meningococcal disease (IMD) is an important cause of meningitis and bacteremia worldwide. Seasonal variation in IMD incidence has long been recognized, but mechanisms responsible for this phenomenon remain poorly understood. The authors sought to evaluate the effect of environmental factors on IMD risk in Philadelphia, Pennsylvania, a major urban center. Associations between monthly weather patterns and IMD incidence were evaluated using multivariable Poisson regression models controlling for seasonal oscillation. Short-term weather effects were identified using a case-crossover approach. Both study designs control for seasonal factors that might otherwise confound the relation between environment and IMD. Incidence displayed significant wintertime seasonality (for oscillation, P < 0.001), and Poisson regression identified elevated monthly risk with increasing relative humidity (per 1% increase, incidence rate ratio = 1.04, 95% confidence interval: 1.004, 1.08). Case-crossover methods identified an inverse relation between ultraviolet B radiation index 1–4 days prior to onset and disease risk (odds ratio = 0.54, 95% confidence interval: 0.34, 0.85). Extended periods of high humidity and acute changes in ambient ultraviolet B radiation predict IMD occurrence in Philadelphia. The latter effect may be due to decreased pathogen survival or virulence and may explain the wintertime seasonality of IMD in temperate regions of North America.

Environmental determinants of campylobacteriosis risk in Philadelphia from 1994 to 2007.

Campylobacter species infections are a common cause of acute gastroenteritis, and may uncommonly be complicated by renal, neurological, and rheumatologic sequelae. Although excess summertime campylobacteriosis has been observed, environmental mechanisms driving disease seasonality are poorly understood. We sought to evaluate the relationship between environmental factors and campylobacteriosis risk in a major North American metropolitan area. We evaluated 1532 cases of campylobacteriosis reported in Philadelphia between 1994 and 2007. We constructed Poisson regression models with oscillatory smoothers, and also used case-crossover design, to evaluate the associations between environmental exposures and disease risk on weekly and daily time scales. Both methods control for confounding by seasonally oscillating environmental factors. Incidence was greatest in June and July, with annual periodicity. Weekly incidence was associated with increasing relative humidity, (incidence rate ratio (IRR) per % 1.017, 95% CI 1.008–1.025), temperature (IRR per °C 1.041, 95% CI 1.011–1.072), and decreasing Delaware River temperature during the same week (IRR per °C 0.922, 95% CI 0.883–0.962), and at 4-week lags (IRR per °C 0.953, 95% CI 0.919–0.990). No acute associations were identified in case-crossover analyses. Our findings affirm the summertime seasonality of campylobacteriosis in Philadelphia, and the link between warm, humid weather and disease risk. However, the link between low river temperatures and enhanced campylobacteriosis risk in humans described here is novel, consistent with known links between watershed temperature and Campylobacter survival, and implicates local watersheds as epidemiologically important reservoirs for foodborne pathogens.

Adolescent Sexually Transmitted Infections and Risk for Subsequent HIV

OBJECTIVES We estimated the risk of HIV associated with sexually transmitted infection (STI) history during adolescence. METHODS We retrospectively studied a cohort of adolescents (n = 75 273, born in 1985-1993) who participated in the Philadelphia High School STD Screening Program between 2003 and 2010. We matched the cohort to STI and HIV surveillance data sets and death certificates and performed Poisson regression to estimate the association between adolescent STI exposures and subsequent HIV diagnosis. RESULTS Compared with individuals reporting no STIs during adolescence, adolescents with STIs had an increased risk for subsequent HIV infection (incidence rate ratio [IRR] for adolescent girls = 2.6; 95% confidence interval [CI] = 1.5, 4.7; IRR for adolescent boys = 2.3; 95% CI = 1.7, 3.1). Risk increased with number of STIs. The risk of subsequent HIV infection was more than 3 times as high among those with multiple gonococcal infections during adolescence as among those with none. CONCLUSIONS Effective interventions that reduce adolescent STIs are needed to avert future STI and HIV acquisition. Focusing on adolescents with gonococcal infections or multiple STIs might have the greatest impact on future HIV risk.

Pseudomonas aeruginosa bacteremia in a dialysis unit: II. Relationship to reuse of coils

Blood for culture was obtained over a six week period from 17 patients undergoing long-term hemodialysis. Bacteremia was detected during 18 of 201 dialyses. Blood drawn during fifteen of these dialyses contained pseudomonas aeruginosa. Ten of the 17 patients (59 per cent) had a Pseudomonas bacteremia some time during the study. Only one patient was symptomatic. The frequency of positive cultures was related to reuse of coils. No cultures were positive until after the fifth use, but by the tenth use, 41 per cent of the dialyses were associated with bacteremia. All coils that were used repeatedly and 32 of 48 of those used only once, grew Ps. aeruginosa when filled with media and incubated. This suggests that the coils were inoculated during dialysis and that benzalkonium chloride, the sterilizing agent, was unable to eradicate this organism. With repeated uses, the number of residual bacteria in the coil became large enough to cause detectable bacteremia during dialysis.