Case Fatality Rates Based on Population Estimates of Influenza-Like Illness Due to Novel H1N1 Influenza: New York City,May–June 2009

Background

The public health response to pandemic influenza is contingent on the pandemic strain''s severity. In late April 2009, a potentially pandemic novel H1N1 influenza strain (nH1N1) was recognized. New York City (NYC) experienced an intensive initial outbreak that peaked in late May, providing the need and opportunity to rapidly quantify the severity of nH1N1.

Methods and Findings

Telephone surveys using rapid polling methods of approximately 1,000 households each were conducted May 20–27 and June 15–19, 2009. Respondents were asked about the occurrence of influenza-like illness (ILI, fever with either cough or sore throat) for each household member from May 1–27 (survey 1) or the preceding 30 days (survey 2). For the overlap period, prevalence data were combined by weighting the survey-specific contribution based on a Serfling model using data from the NYC syndromic surveillance system. Total and age-specific prevalence of ILI attributed to nH1N1 were estimated using two approaches to adjust for background ILI: discounting by ILI prevalence in less affected NYC boroughs and by ILI measured in syndromic surveillance data from 2004–2008. Deaths, hospitalizations and intensive care unit (ICU) admissions were determined from enhanced surveillance including nH1N1-specific testing. Combined ILI prevalence for the 50-day period was 15.8% (95% CI:13.2%–19.0%). The two methods of adjustment yielded point estimates of nH1N1-associated ILI of 7.8% and 12.2%. Overall case-fatality (CFR) estimates ranged from 0.054–0.086 per 1000 persons with nH1N1-associated ILI and were highest for persons ≥65 years (0.094–0.147 per 1000) and lowest for those 0–17 (0.008–0.012). Hospitalization rates ranged from 0.84–1.34 and ICU admission rates from 0.21–0.34 per 1000, with little variation in either by age-group.

Conclusions

ILI prevalence can be quickly estimated using rapid telephone surveys, using syndromic surveillance data to determine expected “background” ILI proportion. Risk of severe illness due to nH1N1 was similar to seasonal influenza, enabling NYC to emphasize preventing severe morbidity rather than employing aggressive community mitigation measures.     

Evidence for ecological divergence across a mosaic of soil types in an Amazonian tropical tree: Protium subserratum (Burseraceae)

Soil heterogeneity is an important driver of divergent natural selection in plants. Neotropical forests have the highest tree diversity on earth, and frequently, soil specialist congeners are distributed parapatrically. While the role of edaphic heterogeneity in the origin and maintenance of tropical tree diversity is unknown, it has been posited that natural selection across the patchwork of soils in the Amazon rainforest is important in driving and maintaining tree diversity. We examined genetic and morphological differentiation among populations of the tropical tree Protium subserratum growing parapatrically on the mosaic of white‐sand, brown‐sand and clay soils found throughout western Amazonia. Nuclear microsatellites and leaf morphology were used to (i) quantify the extent of phenotypic and genetic divergence across habitat types, (ii) assess the importance of natural selection vs. drift in population divergence, (iii) determine the extent of hybridization and introgression across habitat types, (iv) estimate migration rates among populations. We found significant morphological variation correlated with soil type. Higher levels of genetic differentiation and lower migration rates were observed between adjacent populations found on different soil types than between geographically distant populations on the same soil type. P_ST‐F_ST comparisons indicate a role for natural selection in population divergence among soil types. A small number of hybrids were detected suggesting that gene flow among soil specialist populations may occur at low frequencies. Our results suggest that edaphic specialization has occurred multiple times in P. subserratum and that divergent natural selection across edaphic boundaries may be a general mechanism promoting and maintaining Amazonian tree diversity.     

The Association of Cardioprotective Medications with Pneumonia-Related Outcomes

Introduction

Little research has examined whether cardiovascular medications, other than statins, are associated with improved outcomes after pneumonia. Our aim was to examine the association between the use of beta-blockers, statins, angiotensin converting enzyme (ACE) inhibitors, and angiotensin II receptor blockers (ARBs) with pneumonia-related outcomes.

Materials and Methods

We conducted a retrospective population-based study on male patients ≥65 years of age hospitalized with pneumonia and who did not have pre-existing cardiac disease. Our primary analyses were multilevel regression models that examined the association between cardiovascular medication classes and either mortality or cardiovascular events.

Results

Our cohort included 21,985 patients: 22% died within 90 days of admission, and 22% had a cardiac event within 90 days. The cardiovascular medications studied that were associated with decreased 90-day mortality included: statins (OR 0.70, 95% CI 0.63–0.77), ACE inhibitors (OR 0.82, 95% CI 0.74–0.91), and ARBs (OR 0.58, 95% CI 0.44–0.77). However, none of the medications were significantly associated with decreased cardiovascular events.

Discussion

While statins, ACE inhibitors, and ARBs, were associated with decreased mortality, there was no significant association with decreased CV events. These results indicate that this decreased mortality is unlikely due to their potential cardioprotective effects.     

The Clinical Characteristics and Pathological Patterns of Postinfectious Glomerulonephritis in HIV-Infected Patients

Background

Postinfectious glomerulonephritis (PIGN), a form of immune complex GN, is not well-defined in HIV-infected patients. This study characterizes PIGN in this patients’ population and determine the impact of histopathological patterns on renal outcome and mortality.

Methods

HIV-infected patients with PIGN from September 1998 to July 2013 were identified. Archived slides were reviewed by a blinded renal pathologist, classified into acute, persistent and healed PIGN. Groups were compared using Wilcoxon rank-sum and Fisher’s exact test. Survival analyses were performed to determine association of histopathological pattern with renal outcome and mortality.

Results

Seventy-two HIV-infected predominantly African American males were identified with PIGN. Median (interquartile range) age and creatinine at the time of renal biopsy was 48 years (41, 53) and 2.5 mg/dl (1.5, 4.9) respectively. Only 2 (3%) had acute PIGN, 42 (58%) had persistent PIGN and 28 (39%) had healed PIGN. Three patients (4%) had IgA-dominant PIGN. Only 46% of the patients had confirmed positive cultures with Staphylococcus the most common infectious agent. During a median follow up of 17 months, the pathological pattern had no impact on renal outcome (P = 0.95). Overall mortality was high occurring in 14 patients (19%); patients with healed PIGN had significantly increased mortality (P = 0.05).

Conclusion

In HIV-infected patients, Staphylococcus is the most common cause of PIGN. Renal outcome was not influenced by the histopathological pattern but those with healed PIGN had greater mortality which was potentially due to a confounder not accounted for in the study.     

Expressions of Leptin and Insulin‐Like Growth Factor‐I Are Highly Correlated and Region‐Specific in Adipose Tissue of Growing Rats

Objective: Anatomically distinct adipose tissue regions differ in their predominant modality of growth (i.e., cellular hypertrophy vs. hyperplasia). We examined site‐specific patterns of expression of two genes whose products, leptin and insulin‐like growth factor‐I (IGF‐I), could be involved in mediating differential growth and metabolism of white adipose tissue. We also related these patterns of expression to measures of adipose depot cellularity. Research Methods and Procedures: Male Wistar rats were fed ad libitum and studied from ages 7 weeks to ～12 months. Terminal measures of body weights; weights, composition, and cellularity of four white adipose depots; circulating leptin and IGF‐I; and adipose depot‐specific expression levels of leptin and IGF‐I were measured in subsets of rats at 7, 12, 22, 42, and 46 weeks of age. Results: Both leptin and IGF‐I mRNAs are quantitatively expressed in a depot‐specific manner, in the following order: retroperitoneal ? epididymal > mesenteric > subcutaneous inguinal. Furthermore, there is a marked correlation between the expressions of these hormones in the various regions of adipose tissue of rats during the first year of life. The mechanisms that underlie the parallel expressions of leptin and IGF‐I appear to be related to fat‐cell volume. Discussion: Because both leptin and IGF‐I have been implicated in the regulation of energy homeostasis and are both expressed in adipose tissue, the depot‐specific linkage between the two genes suggests interaction at the autocrine level. This interaction may have an important role in determining functional properties particular to individual adipose depots.