Public Health Investigation Research Articles

Public health risk assessment tool: strategy to improve public policy framework for onsite wastewater treatment systems (OWTS)

Public health risk assessment of onsite wastewater treatment systems (OWTS) in the city of Port Harcourt, Nigeria and its environs was carried out between the period of August 2012 and April 2013. The objective of the study was to show how the public health risk assessment tool can be used to improve public policies on OWTS. The study involved desk study reviews of the related literature on OWTS, an audit survey of 245 OWTS in the residential area of the city, a public policy survey of OWTS in Port Harcourt city, a public health risk assessment, field observations and investigations. The results revealed that there were no specific policies, legislative and regulatory standards for sustainability of OWTS practice and no risk assessment considerations in the current policy instruments. In general terms, the public policy instruments of OWTS were found to be inadequate for improved and standard system construction, installation, operations and maintenance, compliance, enforcement and inspection. The outcome of the risk map showed widespread and dispersed risk in the use of OWTS.

The Salmonella In Silico Typing Resource (SISTR): An Open Web-Accessible Tool for Rapidly Typing and Subtyping Draft Salmonella Genome Assemblies.

For nearly 100 years serotyping has been the gold standard for the identification of Salmonella serovars. Despite the increasing adoption of DNA-based subtyping approaches, serotype information remains a cornerstone in food safety and public health activities aimed at reducing the burden of salmonellosis. At the same time, recent advances in whole-genome sequencing (WGS) promise to revolutionize our ability to perform advanced pathogen characterization in support of improved source attribution and outbreak analysis. We present the Salmonella In Silico Typing Resource (SISTR), a bioinformatics platform for rapidly performing simultaneous in silico analyses for several leading subtyping methods on draft Salmonella genome assemblies. In addition to performing serovar prediction by genoserotyping, this resource integrates sequence-based typing analyses for: Multi-Locus Sequence Typing (MLST), ribosomal MLST (rMLST), and core genome MLST (cgMLST). We show how phylogenetic context from cgMLST analysis can supplement the genoserotyping analysis and increase the accuracy of in silico serovar prediction to over 94.6% on a dataset comprised of 4,188 finished genomes and WGS draft assemblies. In addition to allowing analysis of user-uploaded whole-genome assemblies, the SISTR platform incorporates a database comprising over 4,000 publicly available genomes, allowing users to place their isolates in a broader phylogenetic and epidemiological context. The resource incorporates several metadata driven visualizations to examine the phylogenetic, geospatial and temporal distribution of genome-sequenced isolates. As sequencing of Salmonella isolates at public health laboratories around the world becomes increasingly common, rapid in silico analysis of minimally processed draft genome assemblies provides a powerful approach for molecular epidemiology in support of public health investigations. Moreover, this type of integrated analysis using multiple sequence-based methods of sub-typing allows for continuity with historical serotyping data as we transition towards the increasing adoption of genomic analyses in epidemiology. The SISTR platform is freely available on the web at https://lfz.corefacility.ca/sistr-app/.

Tuberculosis in Newborns: The Lessons of the "Lübeck Disaster" (1929-1933).

In an accident later known as the Lübeck disaster, 251 neonates were orally given three doses of the new Bacille Calmette–Guérin (BCG) antituberculosis (TB) vaccine contaminated with Mycobacterium tuberculosis. A total of 173 infants developed clinical or radiological signs of TB but survived the infection, while 72 died from TB. While some blamed the accident on BCG itself by postulating reversion to full virulence, such a possibility was conclusively disproven. Rather, by combining clinical, microbiological, and epidemiological data, the chief public health investigator Dr. A. Moegling concluded that the BCG vaccine had been contaminated with variable amounts of fully virulent M. tuberculosis. Here, we summarize the conclusions drawn by Moegling and point out three lessons that can be learned. First, while mortality was high (approximately 29%), the majority of neonates inoculated with M. tuberculosis eventually overcame TB disease. This shows the high constitutional resistance of humans to the bacillus. Second, four semiquantitative levels of contamination were deduced by Moegling from the available data. While at low levels of M. tuberculosis there was a large spread of clinical phenotypes reflecting a good degree of innate resistance to TB, at the highest dose, the majority of neonates were highly susceptible to TB. This shows the dominating role of dose for innate resistance to TB. Third, two infants inoculated with the lowest dose nevertheless died of TB, and their median time from inoculation to death was substantially shorter than for those who died after inoculation with higher doses. This suggests that infants who developed disease after low dose inoculation are those who are most susceptible to the disease. We discuss some implications of these lessons for current study of genetic susceptibility to TB.

Carbon Monoxide Poisonings from Forklift Use During Produce Packing Operations

ABSTRACTIn August 2013, the North Carolina Division of Public Health investigated a carbon monoxide (CO) exposure on a farm. Two employees were overcome by CO and lost consciousness while using a propane-powered forklift to load produce into a refrigerated trailer backed up to a warehouse. One employee died, and the second employee was admitted to the hospital for hyperbaric oxygen treatment. Eighteen people, ranging in age from 18 to 69 years, were potentially exposed to CO, including the two employees, a family member who discovered the employees, two bystanders who stopped to offer assistance, and 13 first responders. Thirteen people who assisted in the emergency response experienced symptoms such as headache and dizziness, and all 16 who assisted were evaluated in a local hospital emergency department and released after receiving 100% oxygen. Blood tests showed five people (the two employees, family member, and two bystanders) had elevated blood carboxyhemoglobin levels, but all first responders had levels within normal range. Firefighters measured a peak CO concentration of 2214 parts per million in the warehouse. The North Carolina Division of Occupational Safety and Health investigated and determined that the forklift, operated inside the trailer with no ventilation, was the source of the CO. Public health investigation activities included interviewing responders, obtaining ambient CO concentration measurements from the fire department, advising the local health director, reviewing medical records, and developing a line listing of exposed persons. To prevent CO poisoning, employers should consider replacing gas-powered equipment with electric equipment, which does not produce CO.

An Occupational Hazard and Public Health Investigation among the Fabric Workers of India

The present study aims to investigate the occupational hazards, public health and occupational safety among the workers of fabric industry of South India and also promotes the importance of health and safety to the workers in South India. The hazards and risks involved in the fabric or textile industry is highly compared with other industries, and least importance is given to fabric industries. Most of accident does not come to the legal formalities. The people are not aware of health and safety as the workers are uneducated; moreover, management does not pay much importance because promoting industrial health and occupational safety in fabric industry becomes a barrier in implementing industrial health and occupational safety. The major hazards affecting the health of workers are physical, chemical, ergonomically and physiologically hazards; along with these, some others which can create hazards are more working hours and improper ventilation. The risk priority number (RPN) has been found out for all the hazards in the fabric industry, and fault-tree analysis is done for the hazards with highest RPN.

Whole genome multilocus sequence typing as an epidemiologic tool for Yersinia pestis

Human plague is a severe and often fatal zoonotic disease caused by Yersinia pestis. For public health investigations of human cases, nonintensive whole genome molecular typing tools, capable of defining epidemiologic relationships, are advantageous. Whole genome multilocus sequence typing (wgMLST) is a recently developed methodology that simplifies genomic analyses by transforming millions of base pairs of sequence into character data for each gene. We sequenced 13 US Y. pestis isolates with known epidemiologic relationships. Sequences were assembled de novo, and multilocus sequence typing alleles were assigned by comparison against 3979 open reading frames from the reference strain CO92. Allele-based cluster analysis accurately grouped the 13 isolates, as well as 9 publicly available Y. pestis isolates, by their epidemiologic relationships. Our findings indicate wgMLST is a simplified, sensitive, and scalable tool for epidemiologic analysis of Y. pestis strains.

Ciguatera fish poisoning in an international ship crew in Saint John Canada: 2015.

An international ship crew presented for medical care in Saint John, New Brunswick, following rapid onset of gastrointestinal and in some cases neurological and cardiac symptoms after a common fish meal. Ciguatera poisoning was identified as the cause of illness. This report describes the public health investigation and management of this incident, including collaboration between the implicated provincial and federal authorities.

Genomic DNA “finger-printing” in diagnostic virology to clarify discrepant HIV results

BackgroundWe describe two case studies in the antenatal setting where human immunodeficiency virus (HIV) antibody results were discrepant in serial sera. Root cause analysis including genomic DNA fingerprinting was performed. ObjectiveTo analyze serial sera with HIV antibody discrepant results using genomic DNA “finger-printing” to determine whether the sera were from the same or different individuals. Study designIn case study 1, two serial sera with HIV antibody discrepant results, supposedly from a pregnant lady were subjected to root cause analysis. In case study 2, four serial sera ‘from’ a pregnant lady were subjected to root cause analysis. All sera were analyzed forensically using genomic DNA (gDNA) fingerprinting. In the case study 1, public health look-back exercise was done prior to forensic analysis unlike case study 2, when it was planned for later. ResultsCase study 1 gDNA results showed that both sera had identical genotypes and sex indicating that these were from the same individual and that the problem was within automated serum separator pipette syringe. Case study 2 gDNA analysis showed that the 3 of 4 sera were from three different unrelated females indicating an intentional sample mix-up. ConclusionsForensic gDNA “finger-printing” in diagnostic virology changed the direction of the investigations; one pointing to a laboratory issue and the other to an intentional deception by the patient. We recommend considering gDNA fingerprinting in any sample discrepancy investigation prior to any public health investigation. This is the first reported use of gDNA analysis in diagnostic virology.

Calling all Campy--how routine investigation and molecular characterization impacts the understanding of campylobacteriosis epidemiology--Alaska, United States, 2004-2013.

Unlike most jurisdictions in the United States, Alaska performs pulsed-field gel electrophoresis (PFGE) characterization of all Campylobacter sp. isolates at the state public health laboratory--a practice that started in 2002. Moreover, in order to ensure early detection and response to campylobacteriosis outbreaks, the Alaska Section of Epidemiology has investigated all incident Campylobacter sp. case reports since 2004. This report summarizes the public health impact of routine incident case investigations and molecular characterization of all Campylobacter sp. isolates. In sum, we found that these efforts have contributed to better characterization of the epidemiology of campylobacteriosis in Alaska, and facilitated more rapid outbreak detection, more public health investigations, and earlier public health interventions.

Human anthrax outbreak associated with livestock exposure: Georgia, 2012

Human anthrax cases reported in the country of Georgia increased 75% from 2011 (n = 81) to 2012 (n = 142). This increase prompted a case-control investigation using 67 culture- or PCR-confirmed cases and 134 controls matched by residence and gender to investigate risk factor(s) for infection during the month before case onset. Independent predictors most strongly associated with disease in the multivariable modelling were slaughtering animals [odds ratio (OR) 7·3, 95% confidence interval (CI) 2·9-18·1, P 1 km; 15 (12%) of 125 had sick livestock; and 11 (9%) of 128 respondents reported finding dead livestock. We recommend joint public health and veterinary anthrax case investigations to identify areas of increased risk for livestock anthrax outbreaks, annual anthrax vaccination of livestock in those areas, and public awareness education.

Use of Digital Pens for Rapid Epidemiologic Data Collection During a Foodborne Outbreak Investigation.

Public health investigations require rapid assessment, response, and initiation of control measures. In 2012, the New Hampshire Department of Health and Human Services used digital pens to rapidly acquire epidemiologic data during a gastrointestinal illness outbreak. Menus were obtained and a standard questionnaire was administered to exposed persons using digital pens. Questionnaire data were downloaded into an electronic file for analysis. Sixty-nine (74%) of 93 exposed persons completed a questionnaire. Of 6389 data entries made on digital paper, 218 (3%) required correction; of these, 201 (92%) involved a free-form variable and 17 (8%) involved a check-box variable. Digital pens saved an estimated 5 to 6 hours of data-entry time. This outbreak provided an opportunity to assess the value of digital pens for decreasing data-entry burden and allowing more timely data analysis in an emergent setting. Depending on the size of the outbreak and complexity of the survey, there is likely a threshold when use of digital pens would provide a clear benefit to outbreak response. As new technology becomes available for use in emergency preparedness settings, public health agencies must continuously review and update response plans and evaluate investigation tools to ensure timely disease control and response activities.

OP89 – 3062: Escherichia coli 055 associated D+haemolytic uraemic syndrome with severe neurological phenotype in southern England

Objective Diarrhoea associated HUS with neurological involvement in the context of E. Coli 0157 is well described. Spreading microvascular thrombosis caused by combined effects of lipopolysaccharide, cytokine, enhanced shear stress, and verotoxin is purported to play a major role in the development of central nervous dysfunction. Methods We report part of a retrospective case series of 42 patients with D+ HUS. 6 had E Coli055 associated HUS and presented over 7 months in 2014 from a circumscribed geographical area of Southern England. Results 4 boys and 2 girls with median age 40.5 months (range 19m to 60m). Of these 5 had neurological involvement within 2–5 days of start of illness in the form of: generalised seizures – 2, encephalopathy – 2 and focal seizure+hemiplegia – 1. Only the child with hemiplegia had residual neurology at discharge and 6 months follow up. Of the 5, 2 were too unwell to have an MRI scan and the other three had high signal in the basal ganglia or deep white matter or both. EEG in all patients was encephalopathic. All 5 with neurological disease required peritoneal dialysis or haemodialysis or both. 2 required inotropic support. In total 42 patients were admitted with HUS between July 2004 and Jan 2015. 9/42 (21.4%) developed cerebral involvement. 3 children were positive for E. Coli 0157 and 1 was Rotavirus positive. 9 children had atypical HUS and were treated with Ecluzimab, which is a monoclonal antibody directed against complement protein, C5. Conclusion To our knowledge, this is the first case series of D+HUS with E. Coli 055; causing a severe phenotype with neurological involvement in most children in our cohort. Encouragingly only one child has sustained medium term neurological deficit. Epidemiogical and public health investigations are ongoing to try and explain this cohort from a small geographical area.

PP10.13 – 2944: An unusual case of infantile botulism: Clostridium botulinum Bf (C. botulinum Bf) infection in UK

Objective We discuss a rare case of infantile Clostridium botulinum Bf infection, the associated diagnostic pitfalls and paediatric-specific management strategies. Methods A retrospective review of the patient's medical notes was undertaken. Results A previously well, weaned infant presented at 6 months with two days of reduced feeding and salivary pooling. There was no history of honey exposure. Initially, gag-reflex was absent, with preservation of other cranial nerves. Antigravity movements of limbs, reflexes, and respiratory effort, were maintained. Symptoms progressed within a week to reveal hypotonia, absent antigravity movements, with preservation of reflexes, within upper limbs. Lower limb examination was normal. Eye-movements were preserved, however pupils were slowly and asymmetrically reactive. Respiratory decompensation led to intubation and subsequent tracheostomy. Lumbar puncture, metabolic screens, and MRI brain were normal. Neurophysiology showed diffuse, severely attenuated motor nerve amplitude consistent with axonal variant Guillian-Barre Syndrome, thus IVIG was commenced. Due to the atypical presentation of descending paralysis, infantile botulism was considered. Stool specimens were positive for C. botulinum Bf. Botulinum antitoxin therapy (Baby BIG) was initiated, leading to rapid recovery. Public health investigation did not show a reservoir for this infection. Conclusion C. botulinum Bf is rare, with eight previous international cases. Our case is only the second recent presentation in UK. The case confirms that dual C.botulinum neurotoxins should be considered in diagnoses for infants presenting with isolated cranial nerve palsies, including bulbar signs. Furthermore, rapidly descending paralysis involving pupillary mydriasis and poorly reactive pupils are consistent features of infantile botulism. Additionally this case highlights that neurophysiology interpretation in infants is unreliable, with clinical suspicion of botulism guiding investigation. Treatment for infantile botulism centres on Baby BIG therapy. This immunoglobulin is specifically selected for high titres of type A and B “neutralising antibodies”, which combat the most common strains of infantile botulism.

Whole-genome sequencing for national surveillance of Shiga toxin-producing Escherichia coli O157.

National surveillance of gastrointestinal pathogens, such as Shiga toxin-producing Escherichia coli O157 (STEC O157), is key to rapidly identifying linked cases in the distributed food network to facilitate public health interventions. In this study, we used whole-genome sequencing (WGS) as a tool to inform national surveillance of STEC O157 in terms of identifying linked cases and clusters and guiding epidemiological investigation. We retrospectively analyzed 334 isolates randomly sampled from 1002 strains of STEC O157 received by the Gastrointestinal Bacteria Reference Unit at Public Health England, Colindale, in 2012. The genetic distance between each isolate, as estimated by WGS, was calculated and phylogenetic methods were used to place strains in an evolutionary context. Estimates of linked clusters representing STEC O157 outbreaks in England and Wales increased by 2-fold when WGS was used instead of traditional typing techniques. The previously unidentified clusters were often widely geographically distributed and small in size. Phylogenetic analysis facilitated identification of temporally distinct cases sharing common exposures and delineating those that shared epidemiological and temporal links. Comparison with multi locus variable number tandem repeat analysis (MLVA) showed that although MLVA is as sensitive as WGS, WGS provides a more timely resolution to outbreak clustering. WGS has come of age as a molecular typing tool to inform national surveillance of STEC O157; it can be used in real time to provide the highest strain-level resolution for outbreak investigation. WGS allows linked cases to be identified with unprecedented specificity and sensitivity that will facilitate targeted and appropriate public health investigations.

Public Health Investigation of Two Outbreaks of Shiga Toxin-Producing Escherichia coli O157 Associated with Consumption of Watercress.

An increase in the number of cases of Shiga toxin-producing Escherichia coli (STEC) O157 phage type 2 (PT2) in England in September 2013 was epidemiologically linked to watercress consumption. Whole-genome sequencing (WGS) identified a phylogenetically related cluster of 22 cases (outbreak 1). The isolates comprising this cluster were not closely related to any other United Kingdom strain in the Public Health England WGS database, suggesting a possible imported source. A second outbreak of STEC O157 PT2 (outbreak 2) was identified epidemiologically following the detection of outbreak 1. Isolates associated with outbreak 2 were phylogenetically distinct from those in outbreak 1. Epidemiologically unrelated isolates on the same branch as the outbreak 2 cluster included those from human cases in England with domestically acquired infection and United Kingdom domestic cattle. Environmental sampling using PCR resulted in the isolation of STEC O157 PT2 from irrigation water at one implicated watercress farm, and WGS showed this isolate belonged to the same phylogenetic cluster as outbreak 2 isolates. Cattle were in close proximity to the watercress bed and were potentially the source of the second outbreak. Transfer of STEC from the field to the watercress bed may have occurred through wildlife entering the watercress farm or via runoff water. During this complex outbreak investigation, epidemiological studies, comprehensive testing of environmental samples, and the use of novel molecular methods proved invaluable in demonstrating that two simultaneous outbreaks of STEC O157 PT2 were both linked to the consumption of watercress but were associated with different sources of contamination.

Infection Prevention and Control in the Podiatric Medical Setting: Challenges to Providing Consistently Safe Care.

Unsafe practices are an underestimated contributor to the disease burden of bloodborne viruses. Outbreaks associated with failures in basic infection prevention have been identified in nonhospital settings with increased frequency in the United States during the past 15 years, representing an alarming trend and indicating that the challenge of providing consistently safe care is not always met. As has been the case with most medical specialties, there have been public health investigations by state and local health departments, and the Centers for Disease Control and Prevention have identified some instances of unsafe practices that have placed podiatric medical patients at risk for viral, bacterial, and fungal infections. All health-care providers, including podiatric physicians, must make infection prevention a priority in any setting in which care is delivered.

Infection Prevention and Control in the Podiatric Medical Setting. Challenges to Providing Consistently Safe Care.

Unsafe practices are an underestimated contributor to the disease burden of bloodborne viruses. Outbreaks associated with failures in basic infection prevention have been identified in nonhospital settings with increased frequency in the United States during the past 15 years, representing an alarming trend and indicating that the challenge of providing consistently safe care is not always met. As has been the case with most medical specialties, public health investigations by state and local health departments, and the Centers for Disease Control and Prevention, have identified some instances of unsafe practices that have placed podiatric medical patients at risk for viral, bacterial, and fungal infections. All health-care providers, including podiatric physicians, must make infection prevention a priority in any setting in which care is delivered.

Description and utilization of the United States department of defense serum repository: a review of published studies, 1985-2012.

Specimens in the United States Department of Defense (DoD) Serum Repository have accumulated in frozen storage since 1985 when the DoD began universal screening for human immunodeficiency virus. Use of the stored serum for health research has been carefully controlled, but the resulting publications have never been systematically identified or described. The Armed Forces Health Surveillance Center (AFHSC) information systems and open (online) sites were used as data sources. Through 2012, the repository contained 54,542,658 serum specimens, of which 228,610 (0.42%) have been accessed for any purpose. Between 2001 (the first year that comprehensive, digital records were available) and 2012, 65.2% of all approved requests for serum were for healthcare or public health investigations, but greater than 99% of all shipped samples were for research. Using two different methods – a structure search of PubMed and an exhaustive online search based on records from AFHSC – we identified 76 articles published between October 1988 and March 2013 that covered a multitude of infectious diseases, injuries, environmental exposures and mental health conditions through analysis of antibodies, biological metabolic, signaling and regulatory substances, Vitamin D, organochlorines, dioxin, omega-3-fatty acid, and portions of human deoxyribonucleic acid. Despite its operational and scientific value, it appears that the DoD Serum Repository has been underutilized. Changes to policy and increased capacity for specimen processing could increase use of the repository without risking privacy or the availability of specimens for the healthcare of individual service members in the future.

Clenbuterol Food Poisoning from Snake Meat Consumption: An Outbreak of 13 Cases

We report a documented outbreak of clenbuterol food poisoning involving 13 patients who consumed snake meat in Shenzhen. They developed headache, palpitation, tachycardia, hypokalaemia and other symptoms within first 3 hours after exposure. They were initially treated with gastric lavage, fluid and potassium replacement and other supportive measures. All of them completely recovered after admission for up to 48 hours. Public health investigation identified clenbuterol compound in four victims' urine and the food source of snake meat they consumed. (Hong Kong j.emerg.med. 2015;22:46-49)

Clustering Curves based on Change point analysis : A Nonparametric Bayesian Approach

Statistical methods for analyzing disease incidence and mortality data over time and geographical regions have gained considerable interest in recent years due to increasing concerns of public health, health disparity and legitimate resource allocation. Trend analysis of cancer incidence and mortality rates is essential for subsequent public health investigations. For example, the National Cancer Institute provides software for fitting statistical models to track changes in cancer curves. Currently available models for detecting trend changes over time are designed for a single curve. When multiple curves are available, current methods could be applied multiple times, however, this may not be efficient in the statistical sense. This paper proposes a statistical model that allows concurrent change-point estimation and grouping for multiple curves while maintaining local variabilities. The Bayesian analysis is carried out by eliciting a Dirichlet process prior on the relevant func- tional space to model change-points. Improper priors are elicited and the resulting posterior is shown to be valid and proper. The age-adjusted lung cancer mortality rates of U.S. states are analyzed to detect change-points and rates of change as well as clusters of states that share similar trends over time. The procedure is also compared with an approach that group states according to a penalized likelihood