Western gray whales on their summer feeding ground off Sakhalin Island in 2015: who is foraging where?

In the face of cumulative effects of oil and gas activities on the endangered western gray whale, informed management decisions rely on knowledge of gray whale spatial use patterns as a function of demographic group and prey energy. In particular, the gray whale foraging ground off Sakhalin Island consists of two distinct areas (nearshore and offshore) with the offshore feeding area exhibiting markedly high prey energy content. Based on photo-identification data collected from 2002 to 2015, we determined that gray whale use of the offshore feeding area increased with age. Pregnant females were more likely to be sighted only nearshore when nearshore prey energy and the proportion of nearshore energy from amphipods were higher. Likewise, females arriving with calves were less likely to be sighted offshore when the proportion of nearshore energy from amphipods was higher. Photo-identification effort in 2015 was increased substantially, with the intent of maximizing resighting data of individual whales to determine the relative proportion of different demographic groups utilizing the nearshore and offshore feeding areas. Comparing sighting data collected in 2015 with data from all previous years combined, mothers arriving with calves were sighted in the offshore feeding area earlier in 2015, with no evidence that they returned to forage nearshore later in the season. Other reproductive females constituted a higher proportion of the animals foraging nearshore prior to 2015, while juveniles were a higher proportion during 2015. Thus, the offshore feeding area is an important component of the gray whales' annual life cycle, particularly if nearshore prey energy continues to decline, and offshore anthropogenic activities need to be monitored and addressed.

Salmonella Typhimurium environmental reduction in a farrow-to-finish pig herd using a live attenuated Salmonella Typhimurium vaccine.

BACKGROUND: Salmonella Typhimurium is an important zoonotic pathogen in pigs, that can cause clinical disease. Many sow herds and finishing herds are infected with Salmonella, and therefore pose a threat for the contamination of pork and pork products and ultimately consumers. CASE PRESENTATION: This case study describes a farrow-to-finish pig herd, producing its own replacement gilts, which had experienced clinical outbreaks of salmonellosis since 2002. Outbreaks were characterised by profuse diarrhoea, dead pigs and high antimicrobial use (colistin sulphate). The aim of this study was to see whether using vaccination of sows and piglets with Salmoporc®, a live attenuated Salmonella Typhimurium vaccine, in combination with standard hygienic precautions, it was possible to reduce Salmonella Typhimurium to below the bacteriological detection limit. Monitoring of the presence of Salmonella was done using a total of 20 pooled faecal, sock and dust samples per herd visit in the period from September 2016 to October 2020. Within the first 10 months after the start of vaccination in August 2016, there was a rapid reduction in clinical symptoms, antimicrobial usage and the number of Salmonella-positive samples. During the winters of 2017/2018 and 2018/2019 the number of positive samples increased again, however with minimal need to use antimicrobials to treat the affected animals. In July 2019, only two samples from a corridor were positive. In September and November 2019 and in October 2020 all three samplings were completely negative for S. Typhimurium. CONCLUSIONS: This case, together with other longitudinal studies, can be seen as a proof of the principle that long term vaccination with a live attenuated S. Typhimurium vaccine can reduce the level of S. Typhimurium in the herd environment to very low levels within a farrow-to-finish herd initially suffering from clinical salmonellosis. Also, clinical symptoms indicating salmonellosis were no longer observed and antimicrobials to treat clinically diseased pigs were no longer needed.

Piglet coccidiosis in Belgium and the Netherlands: Prevalence, management and potential risk factors.

Piglet coccidiosis caused by Cystoisospora suis is one of the most important causes of diarrhea in suckling piglets. The parasite has a fast development and multiplies quickly and effectively under the conditions of a farrowing unit. Control measures include cleaning and disinfection and anticoccidial treatment. In Europe, toltrazuril-based products are authorized for this purpose and are applied to piglets on affected farms in the first week of life. To observe the effect of treatment and disinfection on the control of piglet coccidiosis in the field, 23 farms (11 from Belgium, 12 from the Netherlands, mean number of sows = 1413) were sampled twice by litter in the second and third week of life and fecal scores and the presence of C. suis oocysts were determined. A questionnaire was used to collect data on farm sizes, management and hygiene measures as well as treatment (product, dose and piglet age). Thirteen farms regularly treated with toltrazuril (treatment age: 1-6 days, mean 4.3 days) and 19 applied disinfection. Parasite excretion was documented on 60.9% and diarrhea on 78.3% of farms and in 34.3%/15.7% of the litters. Only 2.4% of the litters showed both, so subclinical infection appeared to be common. No significant differences between farms that did not treat against coccidiosis and farms that applied toltrazuril was observed with regard to C. suis oocysts shedding and/or diarrhea. However, in litters that were treated within the first three days of life, oocyst excretion was significantly less often observed than in litters with later treatment (p = 0.033). No significant effect of disinfection could be shown, but most farms applied disinfectants that have no proven effect against coccidia (oxygen-releasing agents or glutaraldehyde + ammonia) while the only farm that used chlorocresols (which are effective against coccidia) did not show oocyst shedding. Current control measures thus appear to be insufficient on most of the examined farms. It is therefore recommended to treat piglets timely and to apply effective disinfectants to reduce C. suis infections. Furthermore, regular evaluation of sustained efficacy of all implemented measures are necessary.

Evaluation of multiple-locus variable number of tandem repeats analysis for typing livestock-associated methicillin-resistant Staphylococcus aureus.

BACKGROUND: The increasing occurrence of livestock-associated (LA) methicillin-resistant Staphylococcus aureus (MRSA) associated with the clonal complex (CC) 398 within the past years shows the importance of standardized and comparable typing methods for the purposes of molecular surveillance and outbreak detection. Multiple-locus variable number of tandem repeats analysis (MLVA) has recently been described as an alternative and highly discriminative tool for S. aureus. However, until now the applicability of MLVA for the typing of LA-MRSA isolates from different geographic origin has not been investigated in detail. We therefore compared MLVA and S. aureus protein A (spa) typing for characterizing porcine MRSA from distinct Dutch and German farms. METHODOLOGY/PRINCIPAL FINDINGS: Overall, 134 MRSA isolates originating from 21 different pig-farms in the Netherlands and 36 farms in Germany comprising 21 different spa types were subjected to MLVA-typing. Amplification and subsequent automated fragment sizing of the tandem repeat loci on a capillary sequencer differentiated these 134 isolates into 20 distinct MLVA types. Whereas overall MLVA and spa typing showed the same discriminatory power to type LA-MRSA (p = 0.102), MLVA was more discriminatory than spa typing for isolates associated with the prevalent spa types t011 and t034 (Simpson's Index of Diversity 0.564 vs. 0.429, respectively; p<0.001). CONCLUSION: Although the applied MLVA scheme was not more discriminatory than spa typing in general, it added valuable information to spa typing results for specific spa types (t011, t034) which are highly prevalent in the study area, i.e. Dutch-German border area. Thus, both methods may complement each other to increase the discriminatory power to resolute highly conserved clones such as CC398 (spa types t011, t034) for the detection of outbreaks and molecular surveillance of zoonotic MRSA.

Longitudinal study on transmission of MRSA CC398 within pig herds.

UNLABELLED: ABSBACKGROUND: Since the detection of MRSA CC398 in pigs in 2004, it has emerged in livestock worldwide. MRSA CC398 has been found in people in contact with livestock and thus has become a public health issue. Data from a large-scale longitudinal study in two Danish and four Dutch pig herds were used to quantify MRSA CC398 transmission rates within pig herds and to identify factors affecting transmission between pigs. RESULTS: Sows and their offspring were sampled at varying intervals during a production cycle. Overall MRSA prevalence of sows increased from 33% before farrowing to 77% before weaning. Overall MRSA prevalence of piglets was>60% during the entire study period. The recurrent finding of MRSA in the majority of individuals indicates true colonization or might be the result of contamination. Transmission rates were estimated using a Susceptible-Infectious-Susceptible (SIS-)model, which resulted in values of the reproduction ratio (R0) varying from 0.24 to 8.08. Transmission rates were higher in pigs treated with tetracyclins and ß-lactams compared to untreated pigs implying a selective advantage of MRSA CC398 when these antimicrobials are used. Furthermore, transmission rates were higher in pre-weaning pigs compared to post-weaning pigs which might be explained by an age-related susceptibility or the presence of the sow as a primary source of MRSA CC398. Finally, transmission rates increased with the relative increase of the infection pressure within the pen compared to the total infection pressure, implying that within-pen transmission is a more important route compared to between-pen transmission and transmission through environmental exposure. CONCLUSION: Our results indicate that MRSA CC398 is able to spread and persist in pig herds, resulting in an endemic situation. Transmission rates are affected by the use of selective antimicrobials and by the age of pigs.

Transmission of methicillin resistant Staphylococcus aureus among pigs during transportation from farm to abattoir.

The prevalence of methicillin resistant Staphylococcus aureus (MRSA) in pigs at abattoirs is higher than in pigs sampled on farms. This study investigated whether MRSA negative pigs can become MRSA positive during transportation from the farm to the abattoir after exposure to other pigs and environmental sources of MRSA. Nasal swabs were collected from four batches of pigs during loading at the farm, on arrival at the abattoir and after stunning. Environmental wipes were taken from lorries after transporting pigs and from lairages after holding pigs. All pigs (n=117) tested MRSA negative before transportation. On arrival at the abattoir, 12/117 (10.3%) pigs in two batches tested MRSA positive. In lorries that tested positive after transportation, the prevalence of MRSA positive pigs was 21.1%, whereas no MRSA was detected in pigs that had been transported in lorries that tested negative after transportation. At stunning, all batches and 70/117 (59.8%) pigs tested MRSA positive. Pigs can become MRSA positive in the short period of time during transportation from the farm to stunning at the abattoir.