Ocular surface health with contact lens wear

Eye care practitioners (ECPs) would tend to agree that wearing contact lenses increases the risk for infection, but millions of patients are still fitted with lenses every year because ECPs feel that the risk is manageable and that their patients' eye health can be protected. The Fusarium and Acanthamoeba keratitis outbreaks of years past were a wake-up call to manufacturers, ECPs, and regulatory agencies that risk cannot be managed without diligence, and that the complex relationship between contact lens materials, contact lens solutions, and compliance needs to be better understood in order to optimize the efficacy of contact lens care and improve care guidelines.

Comparative susceptibility of mosquito populations in North Queensland, Australia to oral infection with dengue virus

Dengue is the most prevalent arthropod-borne virus, with at least 40% of the world’s population at risk of infection each year. In Australia, dengue is not endemic, but viremic travelers trigger outbreaks involving hundreds of cases. We compared the susceptibility of Aedes aegypti mosquitoes from two geographically isolated populations with two strains of dengue virus serotype 2. We found, interestingly, that mosquitoes from a city with no history of dengue were more susceptible to virus than mosquitoes from an outbreak-prone region, particularly with respect to one dengue strain. These findings suggest recent evolution of population-based differences in vector competence or different historical origins. Future genomic comparisons of these populations could reveal the genetic basis of vector competence and the relative role of selection and stochastic processes in shaping their differences. Lastly, we show the novel finding of a correlation between midgut dengue titer and titer in tissues colonized after dissemination.

Epidemiological and molecular features of dengue virus type-1 in New Caledonia, South Pacific, 2001–2013

Background The epidemiology of dengue in the South Pacific has been characterized by transmission of a single dominant serotype for 3–5 years, with subsequent replacement by another serotype. From 2001 to 2008 only DENV-1 was reported in the Pacific. In 2008, DENV-4 emerged and quickly displaced DENV-1 in the Pacific, except in New Caledonia (NC) where DENV-1 and DENV-4 co-circulated in 2008–2009. During 2012–2013, another DENV-1 outbreak occurred in NC, the third DENV-1 outbreak in a decade. Given that dengue is a serotype-specific immunizing infection, the recurrent outbreaks of a single serotype within a 10-year period was unexpected. Findings This study aimed to inform this phenomenon by examining the phylogenetic characteristics of the DENV-1 viruses in NC and other Pacific islands between 2001 and 2013. As a result, we have demonstrated that NC experienced introductions of viruses from both the Pacific (genotype IV) and South-east Asia (genotype I). Moreover, whereas genotype IV and I were co-circulating at the beginning of 2012, we observed that from the second half of 2012, i.e. during the major DENV-1 outbreak, all analyzed viruses were genotype I suggesting that a genotype switch occurred. Conclusions Repeated outbreaks of the same dengue serotype, as observed in NC, is uncommon in the Pacific islands. Why the earlier DENV-1 outbreaks did not induce sufficient herd immunity is unclear, and likely multifactorial, but the robust vector control program may have played a role by limiting transmission and thus maintaining a large susceptible pool in the population. Keywords: Dengue; Phylogeny; Genotype; Epidemics; New Caledonia

Nowhere to hide: informal disease surveillance networks tracing state behaviour

Since the revisions to the International Health Regulations (IHR) in 2005, much attention has turned to how states, particularly developing states, will address core capacity requirements attached to the revised IHR. Primarily, how will states strengthen their capacity to identify and verify public health emergencies of international concern (PHEIC)? Another important but under-examined aspect of the revised IHR is the empowerment of the World Health Organization (WHO) to act upon non-governmental reports of disease outbreaks. The revised IHR potentially marks a new chapter in the powers of ‘disease intelligence’ and how the WHO may press states to verify an outbreak event. This article seeks to understand whether internet surveillance response programs (ISRPs) are effective in ‘naming and shaming’ states into reporting disease outbreaks.

Duty in the time of epidemics : what China and Zimbabwe teach us

In November 2002, a man with ‘atypical pneumonia’ treated in Foshan hospital, Guangdong Province, in the People's Republic of China, was the first known case of Severe Acute Respiratory Syndrome (SARS). However, it was not until April 2003 that the Chinese government admitted to the full scale of ‘atypical pneumonia’ cases infected with SARS, two months after the disease had rapidly spread across the world with initial infections in Hong Kong and Vietnam sourced to Guangdong. In 2008, Zimbabwe experienced one of the biggest outbreaks of cholera ever recorded. By February 2009, the disease had spread across all of Zimbabwe's 10 provinces and to neighbouring countries—Botswana, South Africa, Zambia and Mozambique—causing thousands of infections amongst their populations. This article seeks to examine what duties the Chinese and Zimbabwe states had to protect their citizens and the international community from these outbreaks. The article refers to the findings of the International Law Commission's study into the role of states and international organisations in protecting persons in the event of a disaster to consider whether there is an international duty to protect persons from epidemics. The article concludes that both cases reveal a growing concept of protection that entails an international duty to assist individuals when an affected state proves unwilling or unable to assist its own population in the event of a disease outbreak.

Securitizing infectious disease

Over the past decade there has been an increased awareness in the field of international relations of the potential impact of an infectious disease epidemic on national security. While states’ attempts to combat infectious disease have a long history, what is new in this area is the adoption at the international level of securitized responses regarding the containment of infectious disease. This article argues that the securitization of infectious disease by states and the World Health Organization (WHO) has led to two key developments. First, the WHO has had to assert itself as the primary actor that all states, particularly western states, can rely upon to contain the threat of infectious diseases. The WHO's apparent success in this is evidenced by the development of the Global Outbreak Alert Response Network (GOARN), which has led to arguments that the WHO has emerged as the key authority in global health governance. The second outcome that this article seeks to explore is the development of the WHO's authority in the area of infectious disease surveillance. In particular, is GOARN a representation of the WHO's consummate authority in the area of coordinating infectious disease response or is GOARN the product of the WHO's capitulation to western states’ concerns with preventing infectious disease outbreaks from reaching their borders and as a result, are arguments expressing the authority of the WHO in infectious disease response premature?

The international politics of disease reporting : towards post-Westphalianism?

Since the outbreak of Severe Acute Respiratory Syndrome (SARS) in 2003, there has been much discussion about whether the international community has moved into a new post-Westphalian era, where states increasingly recognize certain shared norms that guide what they ought to do in responding to infectious disease outbreaks. In this article I identify this new obligation as the ‘duty to report’, and examine competing accounts on the degree to which states appreciate this new obligation are considered by examining state behaviour during the H5N1 human infectious outbreaks in East Asia (since 2004). The article examines reporting behaviour for H5N1 human infectious cases in Cambodia, China, Indonesia, Thailand and Vietnam from 2004 to 2010. The findings lend strong support to the claim that East Asian states have come to accept and comply with the duty to report infectious disease outbreaks and that the assertions of sovereignty in response to global health governance frameworks have not systematically inhibited reporting compliance.

Seasonal amplitude of hemorrhagic fever with renal syndrome in China : a call for attention to neglected regions

Hemorrhagic fever with renal syndrome (HFRS), a rodent-borne viral disease characterized by fever, hemorrhagic, kidney damage and hypotension, is caused by different species of hantaviruses [1]. Every year, HFRS affects thousands of people in Asia, and more than 90% of these cases are reported in China [2, 3]. Due to its high fatality, HFRS has attracted considerable research attention, and prior studies have predominantly focused on quantifying HFRS morbidity [4], identifying high risk areas [5] and populations [6], or exploring peak time of HFRS occurrence [3]. To date, no study has assessed the seasonal amplitude of HFRS in China, even though it reveals the seasonal fluctuation and thus may provide pivotal information on the possibility of HFRS outbreaks.

National security and pandemics

Pandemics are for the most part disease outbreaks that become widespread as a result of the spread of human-to-human infection. Beyond the debilitating, sometimes fatal, consequences for those directly affected, pandemics have a range of negative social, economic and political consequences. These tend to be greater where the pandemic is a novel pathogen, has a high mortality and/or hospitalization rate and is easily spread. According to Lee Jong-wook, former Director-General of the World Health Organization (WHO), pandemics do not respect international borders. Therefore, they have the potential to weaken many societies, political systems and economies simultaneously.

Spatial-temporal epidemiological analyses of two sympatric, co-endemic alphaviral diseases in Queensland, Australia

Background: The two most reported mosquito-borne diseases in Queensland, a northern state of Australia, are Ross River virus (RRV) disease and Barmah Forest virus (BFV) disease. Both diseases are endemic in Queensland and have similar clinical symptoms and comparable transmission cycles involving a complex inter-relationship between human hosts, various mosquito vectors, and a range of nonhuman vertebrate hosts, including marsupial mammals that are unique to the Australasian region. Although these viruses are thought to share similar vectors and vertebrate hosts, RRV is four times more prevalent than BFV in Queensland. Methods: We performed a retrospective analysis of BFV and RRV human disease notification data collected from 1995 to 2007 in Queensland to ascertain whether there were differences in the incidence patterns of RRV and BFV disease. In particular, we compared the temporal incidence and spatial distribution of both diseases and considered the relationship between their disease dynamics. We also investigated whether a peak in BFV incidence during spring was indicative of the following RRV and BFV transmission season incidence levels. Results: Although there were large differences in the notification rates of the two diseases, they had similar annual temporal patterns, but there were regional variations between the length and magnitude of the transmission seasons. During periods of increased disease activity, however, there was no association between the dynamics of the two diseases. Conclusions: The results from this study suggest that while RRV and BFV share similar mosquito vectors, there are significant differences in the ecology of these viruses that result in different epidemic patterns of disease incidence. Further investigation is required into the ecology of each virus to determine which factors are important in promoting RRV and BFV disease outbreaks.

Outbreak detection algorithms for seasonal disease data : a case study using Ross River virus disease

Background Detection of outbreaks is an important part of disease surveillance. Although many algorithms have been designed for detecting outbreaks, few have been specifically assessed against diseases that have distinct seasonal incidence patterns, such as those caused by vector-borne pathogens. Methods We applied five previously reported outbreak detection algorithms to Ross River virus (RRV) disease data (1991-2007) for the four local government areas (LGAs) of Brisbane, Emerald, Redland and Townsville in Queensland, Australia. The methods used were the Early Aberration Reporting System (EARS) C1, C2 and C3 methods, negative binomial cusum (NBC), historical limits method (HLM), Poisson outbreak detection (POD) method and the purely temporal SaTScan analysis. Seasonally-adjusted variants of the NBC and SaTScan methods were developed. Some of the algorithms were applied using a range of parameter values, resulting in 17 variants of the five algorithms. Results The 9,188 RRV disease notifications that occurred in the four selected regions over the study period showed marked seasonality, which adversely affected the performance of some of the outbreak detection algorithms. Most of the methods examined were able to detect the same major events. The exception was the seasonally-adjusted NBC methods that detected an excess of short signals. The NBC, POD and temporal SaTScan algorithms were the only methods that consistently had high true positive rates and low false positive and false negative rates across the four study areas. The timeliness of outbreak signals generated by each method was also compared but there was no consistency across outbreaks and LGAs. Conclusions This study has highlighted several issues associated with applying outbreak detection algorithms to seasonal disease data. In lieu of a true gold standard, a quantitative comparison is difficult and caution should be taken when interpreting the true positives, false positives, sensitivity and specificity.

Molecular analysis of the acinetobacter baumannii biofilm-associated protein

Acinetobacter baumannii is a multidrug-resistant pathogen associated with hospital outbreaks of infection across the globe, particularly in the intensive care unit. The ability of A. baumannii to survive in the hospital environment for long periods is linked to antibiotic resistance and its capacity to form biofilms. Here we studied the prevalence, expression, and function of the A. baumannii biofilm-associated protein (Bap) in 24 carbapenem-resistant A. baumannii ST92 strains isolated from a single institution over a 10-year period. The bap gene was highly prevalent, with 22/24 strains being positive for bap by PCR. Partial sequencing of bap was performed on the index case strain MS1968 and revealed it to be a large and highly repetitive gene approximately 16 kb in size. Phylogenetic analysis employing a 1,948-amino-acid region corresponding to the C terminus of Bap showed that BapMS1968 clusters with Bap sequences from clonal complex 2 (CC2) strains ACICU, TCDC-AB0715, and 1656-2 and is distinct from Bap in CC1 strains. By using overlapping PCR, the bapMS1968 gene was cloned, and its expression in a recombinant Escherichia coli strain resulted in increased biofilm formation. A Bap-specific antibody was generated, and Western blot analysis showed that the majority of A. baumannii strains expressed an ∼200-kDa Bap protein. Further analysis of three Bap-positive A. baumannii strains demonstrated that Bap is expressed at the cell surface and is associated with biofilm formation. Finally, biofilm formation by these Bap-positive strains could be inhibited by affinity-purified Bap antibodies, demonstrating the direct contribution of Bap to biofilm growth by A. baumannii clinical isolates.

The Escherichia coli O157:H7 EhaB autotransporter protein binds to laminin and collagen I and induces a serum IgA response in O157:H7 challenged cattle

Enterohaemorrhagic Escherichia coli (EHEC) are a subgroup of Shiga toxin-producing E. coli that cause gastrointestinal disease with the potential for life-threatening sequelae. Cattle serve as the natural reservoir for EHEC and outbreaks occur sporadically as a result of contaminated beef and other farming products. While certain EHEC virulence mechanisms have been extensively studied, the factors that mediate host colonization are poorly defined. Previously, we identified four proteins (EhaA,B,C,D) from the prototypic EHEC strain EDL933 that belong to the autotransporter (AT) family. Here we characterize the EhaB AT protein. EhaB was shown to be located at the cell surface and overexpression in E. coli K-12 resulted in significant biofilm formation under continuous flow conditions. Overexpression of EhaB in E. coli K12 and EDL933 backgrounds also promoted adhesion to the extracellular matrix proteins collagen I and laminin. An EhaB-specific antibody revealed that EhaB is expressed in E. coli EDL933 following in vitro growth. EhaB also cross-reacted with serum IgA from cattle challenged with E. coli O157:H7, indicating that EhaB is expressed in vivo and elicits a host IgA immune response.

The plasticity of NBS resistance genes in sorghum is driven by multiple evolutionary processes

Background Increased disease resistance is a key target of cereal breeding programs, with disease outbreaks continuing to threaten global food production, particularly in Africa. Of the disease resistance gene families, the nucleotide-binding site plus leucine-rich repeat (NBS-LRR) family is the most prevalent and ancient and is also one of the largest gene families known in plants. The sequence diversity in NBS-encoding genes was explored in sorghum, a critical food staple in Africa, with comparisons to rice and maize and with comparisons to fungal pathogen resistance QTL. Results In sorghum, NBS-encoding genes had significantly higher diversity in comparison to non NBS-encoding genes and were significantly enriched in regions of the genome under purifying and balancing selection, both through domestication and improvement. Ancestral genes, pre-dating species divergence, were more abundant in regions with signatures of selection than in regions not under selection. Sorghum NBS-encoding genes were also significantly enriched in the regions of the genome containing fungal pathogen disease resistance QTL; with the diversity of the NBS-encoding genes influenced by the type of co-locating biotic stress resistance QTL. Conclusions NBS-encoding genes are under strong selection pressure in sorghum, through the contrasting evolutionary processes of purifying and balancing selection. Such contrasting evolutionary processes have impacted ancestral genes more than species-specific genes. Fungal disease resistance hot-spots in the genome, with resistance against multiple pathogens, provides further insight into the mechanisms that cereals use in the “arms race” with rapidly evolving pathogens in addition to providing plant breeders with selection targets for fast-tracking the development of high performing varieties with more durable pathogen resistance.

Ross River virus disease activity associated with naturally occurring non-tidal flood events in Australia : A systematic review

Ross River virus (RRV) disease is the most common and widespread mosquito-borne disease in Australia, resulting in considerable health and economic cost to communities. While naturally occurring non-tidal flood events may enhance mosquito abundance, little is known about the impact of such events on RRV transmission. This paper critically reviews the existing evidence for an association between naturally occurring non-tidal flood events and RRV transmission. A systematic literature search was conducted on RRV transmission related to flooding and inundation from rain and riverine overflow. Overall, the evidence to support a positive association between flooding and RRV outbreaks is largely circumstantial, with the literature mostly reporting only coincidental occurrence between the two. However, for the Murray River, river flow and height (surrogates of flooding) were positively and significantly associated with RRV transmission. The association between non-tidal flooding and RRV transmission has not been studied comprehensively. More frequent flood events arising from climate change may result in increased outbreaks of RRV disease. Understanding the link between flood events and RRV transmission is necessary if resources for mosquito spraying and public health warnings are to be utilized more effectively and efficiently.