Widespread Dissemination Of Diarrhea Due To Rotavirus Serotype G9p8 In The Solomon Islands After A Focal Flood-Related Outbreak

Background Extreme weather events can precipitate epidemic transmission of diarrhea. We describe a large nationwide epidemic in the Solomon Islands following a focal flash flood disaster on April 3-5, 2015 in the capital city of Honiara. Methods The Early Warning Alert and Response Network surveillance system (EWARN) detected an outbreak of diarrhea in Honiara. We identified cases from EWARN and retrospective review of outpatient registries in Honiara prior to and during the outbreak. We reviewed data from the public adverse event system to identify diarrhea-related deaths. Rapid diagnostic testing for rotavirus was performed on stool samples from cases. RT-PCR analysis was used to genotype rotavirus isolates. Results We identified 4,231 cases of diarrhea in the city of Honiara (pop. 64,609) during an epidemic which occurred following massive flooding. The mean weekly incidence of diarrhea increased from 21.6 to 43.7 cases per 10,000 population during the period before and after flooding. Although flooding was limited to Honiara and the province of Guadalcanal, hospital-based surveillance detected increase in weekly cases of diarrhea in 4 additional provinces situated on separate islands. Peak weekly incidences in these provinces occurred 4-10 weeks after the peak of the outbreak in Honiara. The highest attack rates for diarrhea in Honiara and nationwide were observed in children with age \u3c5 years. In total, 27 children died due to diarrhea related causes, which exceeded the 22 deaths directly attributed to the flash flood emergency. Rotavirus was identified in 26 of 61 (43%) of the outbreak cases for which testing was performed. All four isolates that were genotyped were found to be serotype G9P8. Conclusions Our findings indicate that a disaster sparked a large nationwide epidemic of diarrhea which spread rapidly across islands unaffected by the flood event. Although laboratory testing was limited, rotavirus appears to be an important pathogen in this outbreak. Outbreaks caused by extreme weather events carry a significant burden and should be given large consideration when describing the health impacts of climate change

HARNESSING ANTIBODY KINETICS TO IMPROVE EPIDEMIOLOGIC INFERENCE: CASE STUDIES IN CHOLERA AND SARS-COV-2

Serological surveillance can complement traditional surveillance systems, providing information about exposure to and protection from pathogens at the population-level. In this dissertation, I investigated how longitudinal serum samples could be leveraged to understand the potential of serological surveillance systems for SARS-CoV-2 and Vibrio cholerae. In mid-2020, we measured anti-receptor binding domain (RBD) IgG, IgA, and IgM antibodies using an enzyme-linked immunosorbent assay (ELISA) in longitudinally collected serum samples (<122 days after symptom onset) from 343 PCR confirmed cases of coronavirus disease 2019 (COVID-19). Using samples from 1,548 pre-pandemic controls, we set a threshold to determine seropositivity with perfect specificity. The median time to seroconversion was approximately 12 days for all three isotypes. Anti-RBD IgA and IgM responses were short-lived while IgG responses decayed slowly. We also tested 305 serum samples from 48 culture confirmed cholera cases (collected 2-1083 days post-infection) and 3 uninfected household contacts in Bangladesh for serological biomarkers using a multiplex bead assay (MBA) (IgG, IgA, and IgM for 11 antigens), vibriocidal assay (Ogawa and Inaba serotypes), and ELISA (IgG and IgA for 2 antigens). While vibriocidal responses often had high initial fold-changes (52 and 50 fold-change on-average), several MBA-measured antibodies demonstrated robust responses with similar or longer half-lives. Combining all MBA antibody measures allowed for accurate identification of previous cholera infections including a cross-validated AUC of 92% for infections in the past 200 days. We also tested 248 serum samples from 51 Haitian volunteers vaccinated with killed whole-cell cholera vaccine for the same MBA markers. Both vaccination and infection stimulated anti-Ogawa OSP and anti-Inaba OSP responses. Classification models trained with anti-CT-B, anti-Ogawa OSP, and anti-Inaba OSP IgG measurements to detect individuals infected <200 days prior misclassified recently vaccinated people as recently infected shortly after receiving a second dose. In simulated cross-sectional surveys, we found that measuring additional markers or knowing vaccination status was sufficient to accurately adjust seroincidence estimates. I demonstrated how serological data can be used to measure incidence of previous infection with SARS-CoV-2 and V. cholerae. Integrated approaches for monitoring seroincidence and population-level immunity for more pathogens should be considered to advance surveillance systems

Observation of Exclusive Gamma Gamma Production in p pbar Collisions at sqrt{s}=1.96 TeV

We have observed exclusive \gamma\gamma production in proton-antiproton collisions at \sqrt{s}=1.96 TeV, using data from 1.11 \pm 0.07 fb^{-1} integrated luminosity taken by the Run II Collider Detector at Fermilab. We selected events with two electromagnetic showers, each with transverse energy E_T > 2.5 GeV and pseudorapidity |\eta| < 1.0, with no other particles detected in -7.4 < \eta < +7.4. The two showers have similar E_T and azimuthal angle separation \Delta\phi \sim \pi; 34 events have two charged particle tracks, consistent with the QED process p \bar{p} to p + e^+e^- + \bar{p} by two-photon exchange, while 43 events have no charged tracks. The number of these events that are exclusive \pi^0\pi^0 is consistent with zero and is < 15 at 95% C.L. The cross section for p\bar{p} to p+\gamma\gamma+\bar{p} with |\eta(\gamma)| < 1.0 and E_T(\gamma) > 2.5$ GeV is 2.48^{+0.40}_{-0.35}(stat)^{+0.40}_{-0.51}(syst) pb.Comment: 7 pages, 4 figure

Combined search for the standard model Higgs boson decaying to a bb pair using the full CDF data set

We combine the results of searches for the standard model Higgs boson based on the full CDF Run II data set obtained from sqrt(s) = 1.96 TeV p-pbar collisions at the Fermilab Tevatron corresponding to an integrated luminosity of 9.45/fb. The searches are conducted for Higgs bosons that are produced in association with a W or Z boson, have masses in the range 90-150 GeV/c^2, and decay into bb pairs. An excess of data is present that is inconsistent with the background prediction at the level of 2.5 standard deviations (the most significant local excess is 2.7 standard deviations).Comment: To be published in Phys. Rev. Lett (v2 contains minor updates based on comments from PRL

Shrinking a large dataset to identify variables associated with increased risk of Plasmodium falciparum infection in Western Kenya

Large datasets are often not amenable to analysis using traditional single-step approaches. Here, our general objective was to apply imputation techniques, principal component analysis (PCA), elastic net and generalized linear models to a large dataset in a systematic approach to extract the most meaningful predictors for a health outcome. We extracted predictors for Plasmodium falciparum infection, from a large covariate dataset while facing limited numbers of observations, using data from the People, Animals, and their Zoonoses (PAZ) project to demonstrate these techniques: data collected from 415 homesteads in western Kenya, contained over 1500 variables that describe the health, environment, and social factors of the humans, livestock, and the homesteads in which they reside. The wide, sparse dataset was simplified to 42 predictors of P. falciparum malaria infection and wealth rankings were produced for all homesteads. The 42 predictors make biological sense and are supported by previous studies. This systematic data-mining approach we used would make many large datasets more manageable and informative for decision-making processes and health policy prioritization

Evidence for t\bar{t}\gamma Production and Measurement of \sigma_t\bar{t}\gamma / \sigma_t\bar{t}

Using data corresponding to 6.0/fb of ppbar collisions at sqrt(s) = 1.96 TeV collected by the CDF II detector, we present a cross section measurement of top-quark pair production with an additional radiated photon. The events are selected by looking for a lepton, a photon, significant transverse momentum imbalance, large total transverse energy, and three or more jets, with at least one identified as containing a b quark. The ttbar+photon sample requires the photon to have 10 GeV or more of transverse energy, and to be in the central region. Using an event selection optimized for the ttbar+photon candidate sample we measure the production cross section of, and the ratio of cross sections of the two samples. Control samples in the dilepton+photon and lepton+photon+\met, channels are constructed to aid in decay product identification and background measurements. We observe 30 ttbar+photon candidate events compared to the standard model expectation of 26.9 +/- 3.4 events. We measure the ttbar+photon cross section to be 0.18+0.08 pb, and the ratio of the cross section of ttbar+photon to ttbar to be 0.024 +/- 0.009. Assuming no ttbar+photon production, we observe a probability of 0.0015 of the background events alone producing 30 events or more, corresponding to 3.0 standard deviations.Comment: 9 pages, 3 figure

Precision Top-Quark Mass Measurements at CDF

We present a precision measurement of the top-quark mass using the full sample of Tevatron $\sqrt{s}=1.96$ TeV proton-antiproton collisions collected by the CDF II detector, corresponding to an integrated luminosity of 8.7 $fb^{-1}$. Using a sample of $t\bar{t}$ candidate events decaying into the lepton+jets channel, we obtain distributions of the top-quark masses and the invariant mass of two jets from the $W$ boson decays from data. We then compare these distributions to templates derived from signal and background samples to extract the top-quark mass and the energy scale of the calorimeter jets with {\it in situ} calibration. The likelihood fit of the templates from signal and background events to the data yields the single most-precise measurement of the top-quark mass, \mtop = 172.85 \pm$0.71 (stat)$\pm$0.85 (syst) GeV/c^{2}.$Comment: submitted to Phys. Rev. Let

Measurement of the WZWZ Cross Section and Triple Gauge Couplings in ppˉp \bar p Collisions at s=1.96\sqrt{s} = 1.96 TeV

This Letter describes the current most precise measurement of the $WZ$ production cross section as well as limits on anomalous $WWZ$ couplings at a center-of-mass energy of 1.96 TeV in proton-antiproton collisions for the Collider Detector at Fermilab (CDF). $WZ$ candidates are reconstructed from decays containing three charged leptons and missing energy from a neutrino, where the charged leptons are either electrons or muons. Using data collected by the CDF II detector (7.1 fb$^{-1}$ of integrated luminosity), 63 candidate events are observed with the expected background contributing $8 \pm 1$ events. The measured total cross section $\sigma (p \bar p \to WZ) = 3.93_{-0.53}^{+0.60}(\text{stat})_{-0.46}^{+0.59}(\text{syst})$ pb is in good agreement with the standard model prediction of $3.50\pm 0.21$. The same sample is used to set limits on anomalous $WWZ$ couplings.Comment: Resubmission to PRD-RC after acceptance (27 July 2012

A search for resonant production of ttˉt\bar{t} pairs in $4.8\ \rm{fb}^{-1}ofintegratedluminosityof of integrated luminosity of p\bar{p}collisionsat collisions at \sqrt{s}=1.96\ \rm{TeV}$

We search for resonant production of tt pairs in 4.8 fb^{-1} integrated luminosity of ppbar collision data at sqrt{s}=1.96 TeV in the lepton+jets decay channel, where one top quark decays leptonically and the other hadronically. A matrix element reconstruction technique is used; for each event a probability density function (pdf) of the ttbar candidate invariant mass is sampled. These pdfs are used to construct a likelihood function, whereby the cross section for resonant ttbar production is estimated, given a hypothetical resonance mass and width. The data indicate no evidence of resonant production of ttbar pairs. A benchmark model of leptophobic Z \rightarrow ttbar is excluded with m_{Z'} < 900 GeV at 95% confidence level.Comment: accepted for publication in Physical Review D Sep 21, 201