Does the early frog catch the worm? Disentangling potential drivers of a parasite age–intensity relationship in tadpoles

The manner in which parasite intensity and aggregation varies with host age can provide insights into parasite dynamics and help identify potential means of controlling infections in humans and wildlife. A significant challenge is to distinguish among competing mechanistic hypotheses for the relationship between age and parasite intensity or aggregation. Because different mechanisms can generate similar relationships, testing among competing hypotheses can be difficult, particularly in wildlife hosts, and often requires a combination of experimental and model fitting approaches. We used field data, experiments, and model fitting to distinguish among ten plausible drivers of a curvilinear age–intensity relationship and increasing aggregation with host age for echinostome trematode infections of green frogs. We found little support for most of these proposed drivers but did find that the parsimonious explanation for the observed age–intensity relationship was seasonal exposure to echinostomes. The parsimonious explanation for the aggregated distribution of parasites in this host population was heterogeneity in exposure. A predictive model incorporating seasonal exposure indicated that tadpoles hatching early or late in the breeding season should have lower trematode burdens at metamorphosis, particularly with simulated warmer climates. Application of this multi-pronged approach (field surveys, lab experiments, and modeling) to additional parasite–host systems could lead to discovery of general patterns in the drivers of parasite age–intensity and age–distribution relationships

Outcome of hospitalization for COVID-19 in patients with interstitial lung disease. An international multicenter study

Rationale: The impact of coronavirus disease (COVID-19) on patients with interstitial lung disease (ILD) has not been established. Objectives: To assess outcomes in patients with ILD hospitalized for COVID-19 versus those without ILD in a contemporaneous age-, sex-, and comorbidity-matched population. Methods: An international multicenter audit of patients with a prior diagnosis of ILD admitted to the hospital with COVID-19 between March 1 and May 1, 2020, was undertaken and compared with patients without ILD, obtained from the ISARIC4C (International Severe Acute Respiratory and Emerging Infection Consortium Coronavirus Clinical Characterisation Consortium) cohort, admitted with COVID-19 over the same period. The primary outcome was survival. Secondary analysis distinguished idiopathic pulmonary fibrosis from non–idiopathic pulmonary fibrosis ILD and used lung function to determine the greatest risks of death. Measurements and Main Results: Data from 349 patients with ILD across Europe were included, of whom 161 were admitted to the hospital with laboratory or clinical evidence of COVID-19 and eligible for propensity score matching. Overall mortality was 49% (79/161) in patients with ILD with COVID-19. After matching, patients with ILD with COVID-19 had significantly poorer survival (hazard ratio [HR], 1.60; confidence interval, 1.17–2.18; P = 0.003) than age-, sex-, and comorbidity-matched controls without ILD. Patients with an FVC of <80% had an increased risk of death versus patients with FVC ≥80% (HR, 1.72; 1.05–2.83). Furthermore, obese patients with ILD had an elevated risk of death (HR, 2.27; 1.39−3.71). Conclusions: Patients with ILD are at increased risk of death from COVID-19, particularly those with poor lung function and obesity. Stringent precautions should be taken to avoid COVID-19 in patients with ILD

Tuberculosis In Domestic Pigs In Great Britain 2007-2011

Introduction Mycobacterium bovis infects a wide range of wild and domestic mammals. This study examines the epidemiology of M. bovis in pigs and correlates it with cattle and badgers. Materials and Methods: TB-suspect lesions identified in pigs at British abattoirs between 2007 and 2011 were sampled and mycobacterial isolates identified by culture and spoligo-/VNTR-typing. The geographical distribution of M. bovis and M. avium cases was determined; M. bovis isolates were also mapped against the equivalent genotypes in cattle and badgers. Data regarding the age/number of affected pigs, herd size, anatomical location of lesions and opportunity for contact with wildlife or cattle were also collected. Results Nationwide, TB lesions are as likely to be caused by M. avium (11.7% of TB-suspect lesions) as M. bovis (12.8%). However, in the South-West (SW) and West Midlands (WM) regions, M. bovis predominates (86%). Although similar genotypes occur in cattle and pigs, opportunities for direct contact between these species are rarely observed. Mapping data indicates that one strain in pigs may correlate better with the corresponding cases in badgers. M. bovis is more commonly seen on farms where pigs are kept outdoors or wildlife may have access to pens (77.4%). Conclusion M. bovis is the major cause of TB-suspect lesions in pigs in the SW and WM regions. Breakdowns are most common on farms with lower biosecurity; furthermore one M. bovis genotype correlates better with badger data, than cattle. Pigs may therefore represent a useful sentinel for this strain in the wildlife

Tuberculosis In Domestic Pigs In Great Britain 2007-2011

Introduction Mycobacterium bovis infects a wide range of wild and domestic mammals. This study examines the epidemiology of M. bovis in pigs and correlates it with cattle and badgers. Materials and Methods: TB-suspect lesions identified in pigs at British abattoirs between 2007 and 2011 were sampled and mycobacterial isolates identified by culture and spoligo-/VNTR-typing. The geographical distribution of M. bovis and M. avium cases was determined; M. bovis isolates were also mapped against the equivalent genotypes in cattle and badgers. Data regarding the age/number of affected pigs, herd size, anatomical location of lesions and opportunity for contact with wildlife or cattle were also collected. Results Nationwide, TB lesions are as likely to be caused by M. avium (11.7% of TB-suspect lesions) as M. bovis (12.8%). However, in the South-West (SW) and West Midlands (WM) regions, M. bovis predominates (86%). Although similar genotypes occur in cattle and pigs, opportunities for direct contact between these species are rarely observed. Mapping data indicates that one strain in pigs may correlate better with the corresponding cases in badgers. M. bovis is more commonly seen on farms where pigs are kept outdoors or wildlife may have access to pens (77.4%). Conclusion M. bovis is the major cause of TB-suspect lesions in pigs in the SW and WM regions. Breakdowns are most common on farms with lower biosecurity; furthermore one M. bovis genotype correlates better with badger data, than cattle. Pigs may therefore represent a useful sentinel for this strain in the wildlife

Isolation of a novel thermophilic Campylobacter from cases of spotty liver disease in laying hens and experimental reproduction of infection and microscopic pathology.

The condition known as spotty liver disease or spotty liver syndrome can cause significant mortality in free range laying hen flocks. It has been described in Europe and Australia but the aetiology has not been established. There are similarities between spotty liver disease and avian vibrionic hepatitis, a condition which was reported in the 1950s. A Vibrio-like organism was suspected to be the cause of avian vibrionic hepatitis, although this organism was never fully characterised. We report the isolation of a novel Campylobacter from five separate outbreaks of spotty liver disease. The conditions required for culture, the growth characteristics, electron microscopical morphology and results of the phenotypic tests used in the identification of this novel Campylobacter sp. are described. The novel Campylobacter is slow growing and fastidious and does not grow on media routinely used for isolating Campylobacter sp. The morphology is typical for a Campylobacter sp. and phenotypic tests and a duplex real time PCR test differentiate the novel Campylobacter from other members of the genus. 16S rRNA analysis of 19 isolates showed an identical sequence which appears to represent a hitherto unknown sub lineage within the genus Campylobacter. Experimental intraperitoneal infection of four week old SPF chickens produced microscopic liver pathology indistinguishable from natural disease and the novel Campylobacter was recovered from the experimentally infected chicks. The isolates described appear to be a possible causal organism for spotty liver disease

Isolation of a novel thermophilic Campylobacter from cases of spotty liver disease in laying hens and experimental reproduction of infection and microscopic pathology.

The condition known as spotty liver disease or spotty liver syndrome can cause significant mortality in free range laying hen flocks. It has been described in Europe and Australia but the aetiology has not been established. There are similarities between spotty liver disease and avian vibrionic hepatitis, a condition which was reported in the 1950s. A Vibrio-like organism was suspected to be the cause of avian vibrionic hepatitis, although this organism was never fully characterised. We report the isolation of a novel Campylobacter from five separate outbreaks of spotty liver disease. The conditions required for culture, the growth characteristics, electron microscopical morphology and results of the phenotypic tests used in the identification of this novel Campylobacter sp. are described. The novel Campylobacter is slow growing and fastidious and does not grow on media routinely used for isolating Campylobacter sp. The morphology is typical for a Campylobacter sp. and phenotypic tests and a duplex real time PCR test differentiate the novel Campylobacter from other members of the genus. 16S rRNA analysis of 19 isolates showed an identical sequence which appears to represent a hitherto unknown sub lineage within the genus Campylobacter. Experimental intraperitoneal infection of four week old SPF chickens produced microscopic liver pathology indistinguishable from natural disease and the novel Campylobacter was recovered from the experimentally infected chicks. The isolates described appear to be a possible causal organism for spotty liver disease

Genome reduction for niche association in Campylobacter Hepaticus, a cause of spotty liver disease in poultry

The term "spotty liver disease" (SLD) has been used since the late 1990s for a condition seen in the UK and Australia that primarily affects free range laying hens around peak lay, causing acute mortality and a fall in egg production. A novel thermophilic SLD-associated Campylobacter was reported in the United Kingdom (UK) in 2015. Subsequently, similar isolates occurring in Australia were formally described as a new species, Campylobacter hepaticus. We describe the comparative genomics of 10 C. hepaticus isolates recovered from 5 geographically distinct poultry holdings in the UK between 2010 and 2012. Hierarchical gene-by-gene analyses of the study isolates and representatives of 24 known Campylobacter species indicated that C. hepaticus is most closely related to the major pathogens Campylobacter jejuni and Campylobacter coli. We observed low levels of within-farm variation, even between isolates collected over almost 3 years. With respect to C. hepaticus genome features, we noted that the study isolates had a ~140 Kb reduction in genome size, ~144 fewer genes, and a lower GC content compared to C. jejuni. The most notable reduction was in the subsystem containing genes for iron acquisition and metabolism, supported by reduced growth of C. hepaticus in an iron depletion assay. Genome reduction is common among many pathogens and in C. hepaticus has likely been driven at least in part by specialization following the occupation of a new niche, the chicken liver