A One Health Perspective on the Human-Companion Animal Relationship with Emphasis on Zoonotic Aspects

Over time the human-animal bond has been changed. For instance, the role of pets has changed from work animals (protecting houses, catching mice) to animals with a social function, giving companionship. Pets can be important for the physical and mental health of their owners but may also transmit zoonotic infections. The One Health initiative is a worldwide strategy for expanding collaborations in all aspects of health care for humans, animals, and the environment. However, in One Health communications the role of particularly dogs and cats is often underestimated.

OBJECTIVE

Evaluation of positive and negative One Health issues of the human-companion animal relationship with a focus on zoonotic aspects of cats and dogs in industrialized countries.

METHOD

Literature review.

RESULTS

Pets undoubtedly have a positive effect on human health, while owners are increasing aware of pet's health and welfare. The changing attitude of humans with regard to pets and their environment can also lead to negative effects such as changes in feeding practices, extreme breeding, and behavioral problems, and anthropozoonoses. For the human, there may be a higher risk of the transmission of zoonotic infections due to trends such as sleeping with pets, allowing pets to lick the face or wounds, bite accidents, keeping exotic animals, the importation of rescue dogs, and soil contact.

CONCLUSIONS

One Health issues need frequently re-evaluated as the close human-animal relationship with pet animals can totally differ compared to decennia ago. Because of the changed human-companion animal bond, recommendations regarding responsible pet-ownership, including normal hygienic practices, responsible breeding, feeding, housing, and mental and physical challenges conforming the biology of the animal are required. Education can be performed by vets and physicians as part of the One Health concept.

[Veterinarian: a healthy profession?]

Data of the insurance company Movir reveals that veterinarians are more often occupationally disabled compared to other occupations. The causes for this disability are: problems with the locomotion apparatus, accidents and psychological problems. Regarding the complaints of the locomotion apparatus is found that proportionally between 51 and 65 years there are more vets disabled. In absolute numbers the majority of the problems at Movir involves the farm animal vet. About the relative importance or indemnities of other insurance companies no statements can be made. The localisation of the affections are: lower back, knees, shoulders, neck and wrist/hand. Regarding the accidents is found that a lot of problems happen in the private situation, but that the high percentage of disability caused by accidents compared with other professions is probably caused by the profession related accidents. From the numbers of Movir comes forth that especially working with horses is dangerous, but there is no specific veterinarian skill very risky. Regarding the psychological problems comes forth that there are no differences between men and women. Proportionally from 46 years until 65 years there is a higher incidence of burnout then at younger ages. In absolute numbers more companion animal vets are burnout, but no statements can be made about the relative importance. There is no difference at Movir between the solopractice and the partnership regarding burnout. The professional circumstances playing a role in developing burnout are: a too high workload, problems with colleagues within the partnership, irregular shifts, organisation and management and financial management. The personal aspects of these veterinarians that play a role in burnout are: high expectations and demands, perfectionism and insecurity about the own abilities. In many of the files there were also problems within the private situation.

Sensitivity of Shiga toxin-producing Escherichia coli (STEC) strains for colicins under different experimental conditions

Twenty Escherichia coli strains producing well-characterised colicins were tested for their inhibitory activity against five Shiga toxin-producing E. coli (STEC) strains using different media under aerobic and anaerobic conditions. The five STEC strains used were of serotype O26, O111, O128, O145 and O157:H7 which are frequently isolated serotypes associated with disease in humans. The main route of infection for humans is through the eating of badly cooked or handled beef. The major reservoir for STEC strains in cattle is the rumen. To mimic the situation in the rumen of cattle, overlay assays were also performed under anaerobic conditions in the presence of 30% rumen fluid. Colicins E1, E4, E8-J, K and S4 are most active against STEC strains under anaerobic conditions in the absence or presence of rumen fluid. These colicins will be used in future experiments with the aim to eradicate the presence of STEC in cattle.

Effect of fermented feed on the microbial population of the gastrointestinal tracts of pigs

An in vivo experiment was performed with pigs to study the inhibitory effect of fermented feed on the bacterial population of the gastrointestinal tract. Results demonstrated a significant positive correlation between pH and lactobacilli in the stomach contents of pigs in dry feed as well as in the stomach contents of pigs fed fermented feed. Furthermore, a significant positive correlation between the pH and the numbers of bacteria in the family Enterobacteriaceae in the contents of the stomach of pigs fed dry feed was found. In the stomach contents of pigs fed fermented feed, a significant negative correlation was found between the concentration of the undissociated form of lactic acid and the numbers of Enterobacteriaceae. The numbers of Enterobacteriaceae in the contents of the stomach, ileum, cecum, colon, and rectum of pigs fed fermented feed were significantly lower compared with the contents of the stomach, ileum, caecum, colon, and rectum of pigs fed dry feed. The numbers of total lactobacilli were significantly higher in the stomach contents of pigs fed fermented feed and in the ileum contents of one pig group fed fermented feed compared with the contents of pigs fed dry feed. However, the influence of lactobacilli on numbers of Enterobacteriaceae could not be demonstrated. It was concluded that fermented feed influences the bacterial ecology of the gastrointestinal tract and reduces the levels of Enterobacteriaceae in the different parts of the gastrointestinal tract.

Monitoring of transmission of Salmonella enterica serovars in pigs using bacteriological and serological detection methods

The standard method to detect Salmonella positive pigs is bacteriological examination of the faeces, but in recent years the use of Salmonella-ELISA's have become available to screen pigs for serological evidence of infection. This study was conducted to monitor the transmission of five different Salmonella enterica serovars (S. Typhimurium, S. Brandenburg, S. Panama, S. Livingstone, and S. Goldcoast) in fattening pigs and to test the feasibility of Salmonella-ELISA, using seeder pigs as a mode of transmission. Serovar dependence in transmission was observed. The Salmonella-ELISA proved to be useful to detect S. Typhimurium and S. Brandenburg in herds but was of limited value to demonstrate S. Livingstone, S. Goldcoast, and S. Panama.

Control of VTEC in Dutch livestock and meat production

The Dutch government and the meat industry, recognising VTEC as having important public health, meat quality and economic implications, have taken a number of initiatives within the last 5 years to control VTEC in livestock and meat. These initiatives, brought together last year in a 'Masterplan VTEC', include short-, middle- and long-term priorities. Short-term priorities include advice on interventions in the cases of an outbreak of VTEC associated with a cattle herd, the implementation of handbooks for Good Manufacturing Practice (GMP) in slaughterhouses and deboning plants, and the execution of an action programme on zero-tolerance to faecal contamination of carcasses. Mid-term activities include surveillance of the occurrence of VTEC and other enteropathogens in livestock and meat, and the investigations of VTEC population dynamics in dairy farms, transportation and farm hygiene. In the longer term, this programme aims to produce a system of Integrated Quality Assurance, consolidating effective measures to control VTEC in Dutch livestock and meat, and integrating emerging means for control and prevention.

Inhibition of a glucose-limited sequencing fed-batch culture of Salmonella enterica serovar enteritidis by volatile fatty acids representative of the ceca of broiler chickens

The effects of concentrations of volatile fatty acids on an anaerobic, glucose-limited, and pH-controlled growing culture of Salmonella enterica serovar Enteritidis were studied. Suddenly increasing volatile fatty acids to the concentrations representative of the ceca of 15-day-old broiler chickens caused washout of serovar Enteritidis. In contrast, a sudden increase to the volatile fatty acid concentrations representative of the ceca of younger broiler chickens caused a reduction in the biomass but not washout. Gradually increasing volatile fatty acids caused a gradual decrease in the biomass of serovar Enteritidis. We conclude that the concentrations of volatile fatty acids present in the ceca of broilers with a mature microflora can cause washout of serovar Enteritidis in an in vitro system mimicking cecal ecophysiology.

Genotyping by PCR, of Staphylococcus aureus strains, isolated from mammary glands of cows

A total of 71 Staphylococcus aureus strains isolated from bovine mammary glands were identified and subtyped. The methods used to differentiate between the S. aureus isolates were the DNA polymorphism pattern after amplification with a Polymerase Chain Reaction using several primer combinations and phage typing. The DNA fingerprinting technique using RAPD, ERIC1R and ERIC primers proved to be useful in differentiating isolates of S. aureus. Differentiation of isolates using phage typing gave no additional information compared to the DNA technique. The outbreak of S. aureus in the herd studied was mainly caused by one S. aureus strain. Other strains were only found on three occasions, twice in subclinical infections and once from a case of clinical mastitis. In the latter case the dominant strain was isolated from a different quarter of the same cow. Four of the ten cows studied suffered from clinical mastitis. From those four cows, three remained infected with the same S. aureus strain despite antibiotic treatment.

Epidemiological characteristics of bovine clinical mastitis caused by Staphylococcus aureus and Escherichia coli studied by DNA fingerprinting

OBJECTIVE

To study the epidemiology of clinical mastitis caused by Escherichia coli and Staphylococcus aureus by differentiating isolates with DNA fingerprinting techniques, using polymerase chain reaction.

DESIGN

Milk samples were collected from cases of clinical mastitis in dairy cows. Escherichia coli and S aureus isolates from these cases were compared within and between cows and herds.

SAMPLE POPULATION

Seven dairy herds with an average bulk milk somatic cell count < 150,000/ml, and incidence of cows with clinical mastitis of > 25%/y.

PROCEDURE

Chromosomal DNA was isolated from E coli and S aureus strains isolated from cases of clinical mastitis, and amplified by polymerase chain reaction, using enterobacterial repetitive intergenic consensus primers for E coli and a random amplified polymorphic DNA primer for S aureus. Escherichia coli and S aureus strains were identified and differentiated, using their DNA polymorphism pattern.

RESULTS

Multiple E coli genotypes were found in each of the herds. Persistent infections with E coli were sporadic. Only a limited number of different S aureus genotypes was found in each of the herds studied. Recurrent cases of S aureus mastitis were found in 25% of quarters with clinical S aureus mastitis. Comparing S aureus isolates from different herds indicated that 1 S aureus genotype was most prevalent.

CONCLUSIONS

Because different quarters were infected with different genotypes, it was concluded that E coli is an environmental pathogen, and does not generally spread from quarter to quarter. The hypothesis that S aureus mastitis is a contagious disease, spreading from infected to uninfected quarters, could not be rejected.

Isolation and identification of fimbriae and toxin production by Escherichia coli strains from cows with clinical mastitis

A total of 20 Escherichia coli strains isolated from cases of bovine mastitis were examined for fimbriae production, for the presence of genes coding for enterotoxins (LT and ST1), verotoxins (VT), and for the production of cytotoxic necrotizing factors (CNF1 and CNF2). Fimbriae could be isolated from four strains. The N-terminal amino acid sequence of the fimbriae from two strains, was determined. The two sequences were almost identical and homologous to that of the major subunit of E. coli F17 fimbriae. A DNA probe was derived from this N-terminal sequence and used as probe in hybridization experiments with chromosomal DNA of the 20 strains. To test if the strains contained genes that code for the F17 adhesin and the F17 major subunit, a Polymerase Chain Reaction (PCR) assay was performed with primers based on the nucleotide sequence of the genes. Eleven of 20 strains contained sequences that were homologous with sequences for the F17 fimbrial subunit and the F17 adhesin. Strains were tested directly for toxin production on Hela cells and by PCR for the presence of toxin genes. One of the twenty strains, produced a CNF toxin. No strains reacted positive in the PCR for LT, ST1 and verotoxin genes.

Identification of Escherichia coli strains from cows with clinical mastitis by serotyping and DNA polymorphism patterns with REP and ERIC primers

A number of Escherichia coli strains was isolated during a study of clinical mastitis on seven farms in the Netherlands. From these E. coli strains, 30 were characterised with regard to their serotype and their DNA polymorphism pattern with REP and ERIC primers. Special attention was given to recurrent E. coli mastitis in cows. The combination of serotype and DNA pattern observed, was used to study the epidemiology of clinical E. coli mastitis. The results demonstrated that the PCR reaction with the ERIC primers can be used for differentiation of E. coli strains. The DNA polymorphism patterns showed that E. coli strains isolated from cases of clinical mastitis have a great variability in genotype. More 3 than one case of clinical mastitis associated with E. coli during the same lactation period occurred infrequently. However when it took place, E. coli strains isolated from the separate episodes of inflammation, were in most instances of the same serotype and had the same DNA amplification pattern.