Effects of degree and timing of social housing on reversal learning and response to novel objects in dairy calves

Rodents and primates deprived of early social contact exhibit deficits in learning and behavioural flexibility. They often also exhibit apparent signs of elevated anxiety, although the relationship between these effects has not been studied. To investigate whether dairy calves are similarly affected, we first compared calves housed in standard individual pens (n = 7) to those housed in a dynamic group with access to their mothers (n = 8). All calves learned to approach the correct stimulus in a visual discrimination task. Only one individually housed calf was able to re-learn the task when the stimuli were reversed, compared to all but one calf from the group. A second experiment investigated whether this effect might be explained by anxiety in individually housed animals interfering with their learning, and tested varying degrees of social contact in addition to the complex group: pair housing beginning early (approximately 6 days old) and late (6 weeks old). Again, fewer individually reared calves learned the reversal task (2 of 10 or 20%) compared to early paired and grouped calves (16 of 21 or 76% of calves). Late paired calves had intermediate success. Individually housed calves were slower to touch novel objects, but the magnitude of the fear response did not correlate with reversal performance. We conclude that individually housed calves have learning deficits, but these deficits were not likely associated with increased anxiety

Serotype distribution of Streptococcus pneumoniae causing invasive disease in children in the post-PCV era:A systematic review and meta-analysis

BACKGROUND:Routine immunisation with pneumococcal conjugate vaccines (PCV7/10/13) has reduced invasive pneumococcal disease (IPD) due to vaccine serotypes significantly. However, an increase in disease due to non-vaccine types, or serotype replacement, has been observed. Serotypes' individual contributions to IPD play a critical role in determining the overall effects of PCVs. This study examines the distribution of pneumococcal serotypes in children to identify leading serotypes associated with IPD post-PCV introduction. METHODS:A systematic search was performed to identify studies and surveillance reports (published between 2000 and December 2015) of pneumococcal serotypes causing childhood IPD post-PCV introduction. Serotype data were differentiated based on the PCV administered during the study period: PCV7 or higher valent PCVs (PCV10 or PCV13). Meta-analysis was conducted to estimate the proportional contributions of the most frequent serotypes in childhood IPD in each period. RESULTS:We identified 68 studies reporting serotype data among IPD cases in children. We analysed data from 38 studies (14 countries) where PCV7 was administered and 20 (24 countries) where PCV10 or PCV13 have been introduced. Studies reported early and late periods of PCV7 administration (range: 2001∓13). In these settings, serotype 19A was the most predominant cause of childhood IPD, accounting for 21.8% (95%CI 18.6∓25.6) of cases. In countries that have introduced higher valent PCVs, study periods were largely representative of the transition and early years of PCV10 or PCV13. In these studies, the overall serotype-specific contribution of 19A was lower (14.2% 95%CI 11.1∓18.3). Overall, non-PCV13 serotypes contributed to 42.2% (95%CI 36.1∓49.5%) of childhood IPD cases. However, regional differences were noted (57.8% in North America, 71.9% in Europe, 45.9% in Western Pacific, 28.5% in Latin America, 42.7% in one African country, and 9.2% in one Eastern Mediterranean country). Predominant non-PCV13 serotypes overall were 22F, 12F, 33F, 24F, 15C, 15B, 23B, 10A, and 38 (descending order), but their rank order varied by region. CONCLUSION:Childhood IPD is associated with a wide number of serotypes. In the early years after introduction of higher valent PCVs, non-PCV13 types caused a considerable proportion of childhood IPD. Serotype data, particularly from resource-limited countries with high burden of IPD, are needed to assess the importance of serotypes in different settings. The geographic diversity of pneumococcal serotypes highlights the importance of continued surveillance to guide vaccine design and recommendations