published_or_final_version / China Development Studies / Master / Master of Arts in China Development Studies

This dissertation examines factors associated with healthcare-associated infections (HAIs) in four acute care hospitals located in New York City. Specifically, this investigation focuses on the role that the physical environment plays with regard to patient-to-patient transmission. The initial analyses describe the scope of the problem by reporting the incidence of HAIs and antimicrobial resistance over a seven-year period in the study institutions. In total, 19,052 HAIs were identified among 761,426 discharges. HAI rates fell over time within all hospitals and for all organisms and infection types included in the study, and the odds of acquiring an HAI decreased significantly over time for all organisms. Resistance levels were stable for Enterococcus spp., Staphylococcus aureus, Acinetobacter baumannii, and Streptococcus pneumoniae. Multidrug resistance increased for Pseudomonas aeruginosa and decreased for Klebsiella pneumoniae, though imipenem resistance among K. pneumoniae climbed sharply in 2011. A systematic literature review is presented to summarize what is known and unknown about how patients’ exposure to infected or colonized concurrent roommates and prior bed occupants affects their risk of developing HAIs. Eighteen articles meeting the inclusion criteria were identified. More than half reported at least one statistically significant positive association between the infection/colonization status of a roommate or previous room occupant and the development of HAIs. Only a single article identified a statistically significant negative association. The remainder found no associations that reached statistical significance, though this may be due to the fact that they were insufficiently powered. The dissertation concludes with a matched case-control study designed to quantify the association between having a prior bed occupant or roommate with a positive blood, respiratory, urine, or wound culture and subsequent infection with the same organism. In a multivariable analysis controlling for patient characteristics and mutually controlling for each exposure, the odds of being exposed to a prior bed occupant with the same organism were 5.83 (95% Confidence Interval [3.62, 9.39]) times greater for cases versus controls and the odds of being exposed to a roommate with the same organism were 4.82 [3.67, 6.34] times greater.

In this research, three methods of aerosol generation, and their subsequent propagation, are investigated experimentally. These experiments provided insight into the potential risk aerosol can have pertaining to the spread of infectious disease such as COVID – 19. The first of which investigated an alternative generation route that may exist given the discovery of small numbers of viable viruses in urine and stool samples. Flushing biomatter can lead to the aerosolization of micro-organisms; thus, there is a likelihood that bioaerosols generated in public restrooms may pose a concern for the transmission of COVID-19, especially since these areas are relatively confined, experience heavy foot traffic, and may suffer from inadequate ventilation. The results indicate that the particular designs tested in the study generate a large number of droplets in the size range 0.3 𝜇𝑚 – 3 𝜇𝑚, which can reach heights of at least 1.52 m. This highlights the need for incorporating adequate ventilation in the design and operation of public spaces, which can help prevent aerosol accumulation in high occupancy areas and mitigate the risk of airborne disease transmission. Secondly, experiments were conducted to evaluate the effectiveness of facial coverings at various distances around a simulated cough. These concluded that due to the gaps along the seal of a face mask, aerosols can escape 360° around a coughing individual. In the final portion of the thesis study, an experimental method was developed and conducted to break up a droplet via mechanical excitation. The results of these experiments showed that when a droplet is placed on a vibrating string, the droplet can be broken into many secondary droplets which is analogous to one speaking or singing thus providing insight as to how vocal cords can generate respiratory aerosols. / Includes bibliography. / Thesis (MS)--Florida Atlantic University, 2021. / FAU Electronic Theses and Dissertations Collection

No description available.

Diarrhea is the second leading cause of death in children under-5; it kills more children than HIV/AIDS, measles, and malaria combined. Despite this significant health burden, our ability to anticipate and prepare for diarrhea outbreaks remains limited. Precipitation and temperature variability have been shown to affect diarrhea dynamics and therefore contribute to outbreak predictions, but the observed environment-diarrhea relationships are complex and context-specific, depending on local pathogen distribution, host population behavior, and physical environments. To date, studies in sub-Saharan Africa, where the burden of under-5 diarrhea is particularly high, are limited due to sparse diarrheal disease surveillance data. In this dissertation, we leverage unique under-5 diarrhea incidence data to explore the effects of meteorological variability on childhood diarrhea incidence and develop a real-time forecasting system for diarrheal disease in Botswana, where diarrhea remains an important cause of childhood morbidity and mortality. The study focuses in Chobe District, which has an annual dry (April – September) and wet (October – March) season, during which the Chobe River, the primary source of drinking water in the region, floods. Weekly cases of under-5 diarrhea in Chobe District exhibit strong seasonal dynamics with biannual outbreaks occurring during the wet and the dry season. In Chapter 1, we show that wet season diarrhea incidence is strongly associated with increased rainfall and Escherichia coli concentrations in the Chobe River, while dry season incidence is associated with declines in Chobe River flood height and increased total suspended solids in the river. In Chapter 2, we confirm the existence of an El Niño-Southern Oscillation teleconnection with southern Africa by demonstrating that La Niña conditions are associated with cooler temperatures, increased rainfall, and higher flooding in Chobe District during the wet season. In turn, we show that La Niña conditions lagged 0-5 months are associated with higher than average incidence of under-5 diarrhea in the early wet season (December – February). In Chapter 4, we develop and test an epidemiological forecast model for childhood diarrheal disease in Chobe District. The prediction system uses a compartmental susceptible-infected-recovered-susceptible (SIRS) model coupled with Bayesian data assimilation to infer relevant epidemiological parameter values and generate retrospective forecasts. The model system accurately forecasts diarrhea outbreaks up to six weeks before the predicted peak of the outbreak, and prediction accuracy increases over the progression of the outbreak. Many forecasts generated by the model system are more accurate than predictions made using only historical data trends. This dissertation work is an important step forward in our understanding of the links between proximal and distal climatic variability and childhood diarrhea in arid regions of sub-Saharan Africa. Furthermore, it advances methods for generating accurate long-term and short-term forecasts of under-5 diarrhea. We demonstrates the potential use of ENSO data, which are publicly available, to prepare for and mitigate diarrheal disease outbreaks in a low-resource setting up to 5 months in advance, and develop a model-inference system that can generate accurate predictions during an outbreak. Deaths caused by diarrhea are preventable using low-cost treatments. Hence, accurate predictions of diarrhea outbreak magnitudes could help healthcare providers and public health officials prepare for and mitigate the significant morbidity and mortality resulting from diarrhea outbreaks.

Community-associated methicillin-resistant Staphylococcus aureus has been an increasing public health problem since its emergence in the 1990s and incarcerated populations are at disproportionately high-risk for colonization and infection. However, few studies have investigated why levels of S. aureus remain endemic in correctional settings in the absence of an outbreak. The overall objective of this dissertation was to evaluate S. aureus transmission in two maximum-security prisons using a molecular epidemiologic approach and data collected on over 2,700 inmates from 2009 – 2013. The objective of this dissertation was met using three aims. First, a systematic literature review was conducted to identify studies that used social network analysis (SNA) to evaluate infectious disease transmission via non-sexual/non-injection drug use contact pathways to detect influences of social networks on disease risk. Results of the review demonstrated that SNA approaches in infectious disease epidemiology are flexible and can be used to enhance traditional contact investigations, reveal granular patterns of transmission, evaluate influences of high-risk behaviors and activities, and identify both protective and causal effects resulting from context-specific social interactions. Second, changes in the distribution and diversity of S. aureus isolates with increasing length of incarceration were assessed. The results revealed some evidence for S. aureus transmission based on greater representation of certain strains; however, the genetic diversity of S. aureus was high regardless of length of time served. Third, the influence of social interactions among prison inmates on S. aureus colonization status was examined using SNA. The results showed that S. aureus colonized inmates were more likely to spend time in social groups and that the mechanisms of transmission differed for men and women. For women, the association was driven by being centrally located in the social network and for men it was driven by higher proportions of colonized inmates in close proximity. Overall, the results of this dissertation support the hypothesis that S. aureus is transmitted within prisons as a result of direct skin-to-skin contact and/or exposure to contaminated environmental surfaces. However, the results also demonstrate that, in the absence of an outbreak, S. aureus transmission within prisons is low indicating that endemic levels of S. aureus are primarily maintained by the constant introduction of clones into prisons from jails and the community.

Mycobacteriosis is a common disease of laboratory zebrafish (Danio rerio). Different infection patterns occur in zebrafish depending on mycobacterial species. Mycobacterium marinum and M. haemophilum produce virulent infections associated with high mortality, whereas M. chelonae is more wide spread and not associated with high mortality. Identification of mycobacterial infections to the species level provides important information for making management decisions. Observation of acid-fast bacilli in histological sections or tissue imprints is the most common diagnostic method for mycobacteriosis in fish, but only allows for diagnosis to the genus level. Mycobacterial culture, followed by molecular or biochemical identification is the traditional approach for species identification, but recently it has been shown that DNA of diagnostic value can be retrieved from paraffin blocks. Type of fixative, time in fixative before processing, species of mycobacteria, and severity of infection were investigated as parameters to determine if the hsp gene PCR assay (primer set HS5F/hsp667R) could detect and amplify mycobacterial DNA from paraffin-embedded zebrafish. Whole zebrafish were experimentally infected with either M. chelonae or M. marinum, and then preserved in 10% neutral buffered formalin or Dietrich's fixative for 3, 7, 21 and 45 days. Subsequently, fish were evaluated by H&E and Fite's acid-fast stains to detect mycobacteria within granulomatous lesions. The PCR assay was quite effective, and obtained PCR product from 75% and 88% of the M. chelonae and M. marinum infected fish, respectively. Fixative type, time in fixative, and mycobacterial species showed no statistical relationship with the efficacy of the PCR test. Regarding natural transmission, zebrafish are capable of contracting mycobacterial infections by feeding on infected fish tissue, but other natural routes have not been clearly elucidated. Free living amoebae have been shown to be vectors for mycobacteria and their virulence is enhanced when residing in these protozoans. Paramecium caudatum are commonly used as a first food for zebrafish, and I investigated this ciliate's potential to serve as a vector of Mycobacterium marinum and M. chelonae. The ability of live P. caudatum to transmit these mycobacteria to larval, juvenile and adult zebrafish was evaluated. Infections were defined by histologic observation of granulomas containing acid-fast bacteria in extraintestinal locations. In both experiments, fish fed paramecia containing mycobacteria became infected at a higher incidence than controls. Larvae (exposed at 4 days post hatch) fed paramecia with M. marinum exhibited an incidence of 30% (24/80) and juveniles (exposed at 21 days post hatch) showed 31% incidence (14/45). Adult fish fed gelatin diets containing bacteria within paramecia or mycobacteria alone for 2 wk resulted in infections when examined 8 wk after exposure: M. marinum OSU 214; in paramecia 47% (21/45; 3.5 x 10⁵ dose/fish/day), M. marinum CH in paramecia 47% (9/19; 3.6 x 10⁵ dose/fish/day), M. chelonae in paramecia 38% (5/13; 3.5 x 10⁵ dose/fish/day). I investigated the ability of mycobacteria to persist within paramecia, as this has previously been demonstrated in amoebae. Gram negative bacteria ingested by paramecia were processed within an hour. In contrast, I determined using GFP-labeled Mycobacterium marinum that mycobacteria can persist within paramecia digestive vacuoles. The concentration of M. marinum at 1 hour was similar to that at the time of ingestion. Twenty-four hours post-ingestion and later there was significant decline in M. marinum concentrations compared to time of ingestion, but M. marinum continued to persist inside digestive vacuoles for up to one week. My results demonstrate for the first time that Paramecium caudatum can act as a vector for mycobacteria. This provides a useful animal model for evaluation of natural mycobacterial infections and demonstrates the possibility of mycobacterial transmission in zebrafish facilities via contaminated paramecia cultures. / Graduation date: 2013 / Access restricted to the OSU Community at author's request from April 2, 2013 - April 2, 2015

published_or_final_version / Community Medicine / Doctoral / Doctor of Philosophy

No description available.

Since the first detected cases of Middle East Respiratory Syndrome Coronavirus (MERS-CoV), a respiratory virus capable of causing severe human illness, surveillance and research have focused on identification of the source of primary human MERS-CoV infections. Within the One Health framework which recognizes the interconnectedness of human, animal, and environmental health, various animal hosts were investigated as sources of human infection because most emerging infectious diseases are zoonoses – pathogens spilling over from an animal host to a human. A systematic literature review was conducted to synthesize knowledge about MERS-CoV infections in livestock animals and zoonotic transmission of MERS-CoV to humans. Dromedary camels are the presumptive source of primary human MERS-CoV infections, but the importance, frequency, and specific mechanisms of camel-to-human MERS-CoV transmission have not been well characterized. Further, it is unknown what potential barriers will be faced when implementing basic biosecurity interventions to prevent zoonotic transmission at occupational sites where individuals regularly work or interact with dromedary camels. This dissertation addressed these knowledge gaps through a study of MERS-CoV serology and knowledge, attitudes, and beliefs about camel-to-human disease risks and basic biosecurity interventions in Jordan. This study detected individuals with low MERS-CoV neutralizing antibody titers in Jordan and found an association between regular work or interaction with dromedary camels or their living environments and evidence of MERS-CoV infection. Specific behavioral practices were not associated with evidence of MERS-CoV infection among those who regularly work or interact with dromedary camels or their living environments in Jordan. The study also identified multiple important barriers that may be faced when implementing basic biosecurity interventions in this population, including personal protective equipment (PPE) use and frequent handwashing. There were widespread ingrained beliefs that dromedary camels cannot transmit disease to humans and that camel milk and camel urine are beneficial to human health. Among camel workers, reported PPE use was low and frequent handwashing was uncommon. Only a few camel workers felt they would use PPE even if made freely available at their place of work. In conclusion, this dissertation provides further evidence that dromedary camel exposure is an important pathway in the epidemiology of primary human MERS-CoV infections in Jordan. The findings also support the notion that an intervention that simply provides basic biosecurity materials such as PPE and handwashing stations is likely to be ineffective in this population, and that identified barriers should be addressed to motivate behavioral change. Future studies are proposed including a longitudinal cohort study of individuals at risk for MERS-CoV that can detect individual seroconversion over time, track antibody responses among those who seroconvert, and evaluate key sub-exposures among those who are occupationally exposed to dromedary camels; as well as a pilot study to evaluate the feasibility, acceptability, and sustainability of a multifaceted biosecurity intervention that provides materials as well as training and education targeting the knowledge, attitude, and belief barriers identified.