Genome-wide association analysis for susceptibility to infection by Mycobacterium avium ssp. paratuberculosis in US Holsteins

Paratuberculosis, or Johne's disease, is a chronic, granulomatous, gastrointestinal tract disease of cattle and other ruminants caused by the bacterium Mycobacterium avium subspecies paratuberculosis (MAP). Control of Johne's disease is based on programs of testing and culling animals positive for infection with MAP and concurrently modifying management to reduce the likelihood of infection. The current study was motivated by the hypothesis that genetic variation in host susceptibility to MAP infection can be dissected and quantifiable associations with genetic markers identified. Two separate GWAS analyses were conducted, the first using 897 genotyped Holstein artificial insemination sires with phenotypes derived from incidence of MAP infection among daughters based on milk ELISA testing records. The second GWAS analysis was a case-control design using US Holstein cows phenotyped for MAP infection by serum ELISA or fecal culture tests. Cases included cows positive for either serum ELISA, fecal culture, or both. Controls consisted of animals negative for all tests conducted. A total of 376 samples (70 cases and 306 controls) from a University of Minnesota Johne's management demonstration project and 184 samples (76 cases and 108 controls) from a Michigan State University study were used. Medium-density (sires) and high-density (cows) genotype data were imputed to full genome sequence for the analyses. Marker-trait associations were analyzed using the single-step (ss)GWAS procedure implemented in the BLUPF90 suite of programs. Evidence of significant genomic contributions for susceptibility to MAP infection were observed on multiple chromosomes. Results were combined across studies in a meta-analysis, and increased support for genomic regions on BTA7 and BTA21 were observed. Gene set enrichment analysis suggested pathways for antigen processing and presentation, antimicrobial peptides and natural killer cell-mediated cytotoxicity are relevant to variation in host susceptibility to MAP infection, among others. Genomic prediction was evaluated using a 5-fold cross-validation, and moderate correlations were observed between genomic breeding value predictions and daughter averages (∼0.43 to 0.53) for MAP infection in testing data sets. These results suggest that genomic selection against susceptibility to MAP infection is feasible in Holstein cattle.

Effect of school reopening on SARS-CoV-2 incidence in a low-prevalence region: Prospective SARS-CoV-2 testing in healthcare workers with primary school-attending children versus without children living at home

Coronavirus disease 2019 (COVID-19) often presents asymptomatically or milder in children compared to adults. The role of young children in the transmission of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) remains largely unknown. In the Netherlands, the first action of loosening the partial lockdown that had been implemented to reduce SARS-CoV-2 transmission was the reopening of primary schools on 1 May 2020. We subsequently conducted a prospective cohort study among healthcare workers (HCWs) with primary school-attending children versus HCWs without children living at home. We tested each HCW three times for SARS-CoV-2 from May 20 to June 15 2020 at 1-week intervals. In total, 832 nasopharyngeal swabs were taken from 283 HCWs with primary school-attending children living at home and 864 nasopharyngeal swabs from 285 HCWs without children living at home. All nasopharyngeal swabs tested negative for SARS-CoV-2. In our region with a low population density and low SARS-CoV-2 prevalence, reopening of primary schools did not lead to an increase in infections. The results of this study may serve as an example for the implementation of regional strategies to reduce SARS-CoV-2 transmission in countries with large variations in both population density and SARS-CoV-2 prevalence.

Treatment of keratinocyte carcinoma in elderly patients - a review of the current literature

A large percentage of the patients with keratinocyte carcinoma (KC, formerly known as non‐melanoma skin cancer) is of advanced age and often too frail for standard therapies. However, no specific treatment recommendations are given for this population. This review aimed to give an overview of the current literature on the best practice for the treatment of elderly patients with KC. A literature search was performed in MEDLINE, using ‘keratinocyte carcinoma’, ‘elderly’, ‘treatment’ and various synonyms. Case reports, reviews, comments, non‐English literature and studies with a sample size <15 were excluded. After selection, a total of 47 studies were reviewed. Two types of studies were identified, focusing on (I) the effect of age on treatment outcomes and (II) alternative treatment schedules for elderly patients. Studies on surgery, the gold standard, describe larger lesions and defect size in the elderly population. Recurrence rate, complication rate and disease‐specific survival were not affected by age. Depending on the expected morbidity of a suggested (re‐)excision and patient preferences, a conservative watchful waiting policy can be agreed upon as a shared decision. Other common treatment modalities, such as adjuvant radiotherapy, photodynamic therapy and systemic therapy for basal cell carcinoma (BCC), show comparable results in the elderly and younger population. Alternative treatment schedules for elderly patients include primary hypofractionated radiotherapy, which seems effective and well‐tolerated, although research is limited to case series. Additionally, localized and topical treatments seem safe and effective especially for low‐risk tumours. Data are lacking on the efficacy of systemic therapies of metastatic KC in elderly patients. Efficacy of most treatments (with the exception of photodynamic therapy) is not dependent on age. There is need for more research on the efficacy of adjusted treatment modalities, such as hypofractionated radiotherapy and palliative or curative systemic treatment.