Browsing by Subject "Ebola"

Health care workers (HCWs) are key personnel for ending outbreaks of deadly viruses and are amongst the most exposed portion of the general population. However, not all viruses present symptomatically leading HCWs to become unknowingly infected. One of the deadliest viruses with circulation of asymptomatic or paucisymptomatic illness that HCWs have had to contain is Ebola virus (EBOV)--and in Kinshasa HCWs have the largest city on the continent in their stewardship with 15 million people [2]. Understanding prevalence, risk, and protective factors for asymptomatic and pauicsymptomatic Ebola virus disease (EVD) in HCWs is essential for the security and prosperity of the city. Methods: A total of 424 HCWs were included in a serosurvey from urban and rural areas in the Kinshasa region of the Democratic Republic of Congo (DRC). An ELISA kit from Filovirus Animal Non-Clinical Group (FANG) measured titer levels of human anti-EBOV glycoprotein IgG. Associations between risk factors and seroreactivity were determined through both univariable and multivariable logistic regression. Results from these analyses were further scrutinized through a sensitivity analysis, changing our seroreactivity cutoff value from 548 EU/mL, determined through previous studies in Liberia, to 607 EU/mL, the cutoff value described from previous studies in Mali. Results: 12 participants from our cohort with no previous EVD history were seroreactive for EBOV. We determined increased odds of seroeactivity in: HCWs who have actively worked in an EBOV outbreak, individuals over the age of 60, divorced or separated participants, lab technicians, adminstrators, and room attendants. We determined decreased odds of seroreactivity in females, college and university graduates, single individuals, and nurses. In multivariable analysis, we determined conversing with patients and participating in funeral rites were predictors for seroreactivity amongst minimally symptomatic HCWs. No significant changes to our findings occurred upon further scrutiny in our sensitivity analysis. When compared to cohorts from our previous study site, Boende [4], both studies found females, university, and college graduates to have lower odds for seroreactivity while administrators were found to have higher odds of seroreactivity. Conclusions: Our findings further solidify results from our previous study site and offer additional evidence of asymptomatic and paucisymtpomatic EVD. However, further analysis and testing is required for this cohort to determine better quantitative results. Additional investigation is needed to: determine a cutoff value in DRC for the FANG ELISA kit, detect if transmission from minimally symptomatic individuals occurs, and evaluate if seroreactivity equates to immunity for individuals.

Background: Outbreaks of infectious diseases such as Ebola have dramatic economic impacts on affected nations due to significant direct costs and indirect costs, as well as increased expenditure by the government to meet the health and security crisis. Despite its dense population, Nigeria was able to contain the outbreak swiftly and was declared Ebola free on 13th October 2014. Although Nigeria’s Ebola containment success was multifaceted, the private sector played a key role in Nigeria’s fight against Ebola. An epidemic of a disease like Ebola, not only consumes health resources but also detrimentally disrupts trade and travel to impact both public and private sector resulting in the ‘fearonomic’ effect of the contagion. In this thesis, I have defined ‘fearonomics’ or the ‘fearonomic effects’ of a disease as the intangible and intangible economic effects of both informed and misinformed aversion behavior exhibited by individuals, organizations, or countries during an outbreak. During an infectious disease outbreak, there is a significant potential for public-private sector collaborations that can help offset some of the government’s cost of controlling the epidemic.

Objective: The main objective of this study is to understand the ‘fearonomics’ of Ebola in Nigeria and to evaluate the role of the key private sector stakeholders in Nigeria’s Ebola response.

Methods: This retrospective qualitative study was conducted in Nigeria and utilizes grounded theory to look across different economic sectors in Nigeria to understand the impact of Ebola on Nigeria’s private sector and how it dealt with the various challenges posed by the disease and its ‘fearonomic effects'.

Results: Due to swift containment of Ebola in Nigeria, the economic impact of the disease was limited especially in comparison to the other Ebola-infected countries such as Liberia, Sierra Leone, and Guinea. However, the 2014 Ebola outbreak had more than a just direct impact on the country’s economy and despite the swift containment, no economic sector was immune to the disease’s fearonomic impact. The potential scale of the fearonomic impact of a disease like Ebola was one of the key motivators for the private sector engagement in the Ebola response.

The private sector in Nigeria played an essential role in facilitating the country’s response to Ebola. The private sector not only provided in-cash donations but significant in-kind support to both the Federal and State governments during the outbreak. Swift establishment of an Ebola Emergency Operation Centre (EEOC) was essential to the country’s response and was greatly facilitated by the private sector, showcasing the crucial role of private sector in the initial phase of an outbreak. The private sector contributed to Nigeria’s fight against Ebola not only by donating material assets but by continuing operations and partaking in knowledge sharing and advocacy. Some sector such as the private health sector, telecom sector, financial sector, oil and gas sector played a unique role in orchestrating the Nigerian Ebola response and were among the first movers during the outbreak.

This paper utilizes the lessons from Nigeria’s containment of Ebola to highlight the potential of public-private partnerships in preparedness, response, and recovery during an outbreak.

Human genetic variation can be leveraged to understand the subtleties of how common variants with small effect sizes can alter cellular phenotypes and ultimately affect susceptibility to pathogenic disease. By combining GWAS of different phenotypic scales and basic cell biology, we can answer how a particular SNP affects a disease. This body of work elucidates the biological mechanism of how a SNP in VAC14, which encodes a human scaffolding protein involved in phosphoinositide metabolism, alters susceptibility to Typhoid Fever and other pathogens.

Using Hi-HOST (High-throughput Human in vitro Susceptibility Testing), a GWAS platform for cellular host-pathogen traits, we discovered that the ‘A’ allele of rs8060947 was associated with decreased VAC14 protein expression and increased Salmonella Typhi invasion. We experimentally confirmed the phenotype using RNAi to transiently decrease VAC14 protein expression in LCLs and Helas and saw increased Salmonella Typhi invasion. Further studies, using genetic and pharmacological manipulations were able to determine how VAC14 affects Salmonella Typhi invasion. CRISPR knockout VAC14 cells had a robust increase in invasion, and had increased cholesterol accumulation in the cell. Salmonella preferentially docks to cholesterol on the host plasma membrane as one of the first steps involved in invasion. Thus, increasing cholesterol at the plasma membrane increased the number of docked bacteria and ultimately caused higher invasion percentages.

To confirm the relevance of cholesterol and Salmonella Typhi beyond cell culture, we infected the swim bladder of Zebrafish with S. Typhi. Fish were pretreated with Ezetimibe, an FDA approved cholesterol-reducing drug, and then subsequently infected with S. Typhi. Fish treated with Ezetimibe, had decreased cholesterol staining by filipin, and had increased survival from S. Typhi infections. Additionally, because of the optically transparent nature of the zebrafish embryo we were able to image the fish 24hrs after infection and show that ezetimibe treated fish had higher bacterial clearance.

In addition to the fish studies, a collaboration with Dr. Sarah Dunstan (University of Melbourne) was able to retrospectively determine that VAC14 had an effect on human susceptibility to typhoid fever. The ‘A’ allele for SNP rs8060947, which we showed had decreased VAC14 protein expression and increased S. Typhi invasion in cell culture, was found to be more common in people with typhoid fever, suggesting the ‘A’ allele increases human susceptibility to this disease. All together, we have shown that decreased VAC14 expression causes an increase in cellular cholesterol, leading to an increase in docking and invasion of Salmonella and ultimately increasing your chances of acquiring typhoid fever.

The central role of cholesterol in entry of multiple pathogens led us to hypothesize that natural variation or experimental manipulation of VAC14 expression could play a role in pathogens beyond Salmonella. Here we show that its effects extend beyond bacteria to parasites. With cholesterol regulating entry of Plasmodium into hepatocytes, we hypothesized that increasing the amount of cellular cholesterol in hepatocytes will increase Plasmodium entry. These ideas are being tested in collaboration with Maria Toro and Dr. Emily Derbyshire (Duke University). However, unpublished human genetic data already support the idea that VAC14 regulates susceptibility to malaria infection. The same SNP associated with Salmonella invasion (rs8060947) is associated with malaria risk in African populations (Gavin Band and the MalariaGEN Consortium, personal communication).

VAC14 may also affect pathogen entry through its role in regulation of endosomal trafficking. VAC14 forms a complex with the FIG4 phosphatase and PIKfyve kinase to modulate endosomal trafficking through the metabolism of PtdIns(3,5)P2. Recently, FIG4 and PIKfyve were found to be necessary for Ebola entry in a somatic cell genetic screen. Using our VAC14 CRISPR knockout cells we determined that cells mutated for VAC14 had a similar phenotype. Ebola virus-like-particle (VLP) entry decreased dramatically in cells lacking VAC14. While we discovered that VAC14 affects cellular cholesterol, its main reported function is to regulate endosomal trafficking. We hypothesize that lack of VAC14 interferes with proper endosomal maturation and thus prevents the Ebola VLP from reaching its intracellular receptor NPC1 and exiting into the cytoplasm.

The common allele (A) that alters VAC14 expression is associated with decreased protein synthesis, and increased susceptibility to both Salmonella and Malaria infection. On the other hand, decreased VAC14 expression inhibits proper endolysosomal trafficking, inhibiting Ebola infection. These two mechanisms of affecting different infectious diseases may provide opposing forces in an example of balancing selection.