Eradication of targeted species of internal parasites

Eradication can be defined as the permanent reduction to zero of the incidence of infection caused by a specific agent as a result of deliberate efforts. Eradication strategies must be designed to increase access to and utilization of veterinary and animal health support services beyond that normally achieved by routine services. Consequently, before undertaking an eradication program, proponents must be certain that they can be sure of a commitment of resources sufficient to complete the project. A helminth eradication campaign would require the application of anthelmintics to all hosts at a level aimed at killing heterozygote resistant individuals. This strategy runs counter to the prevailing opinion that resistance to chemicals will always occur and control schemes should accept some production loss by letting a proportion of parasites escape selection (in refugia) and thereby increase the useful life of the chemical. Under certain circumstances, environmental constraints may make some species of parasitic nematodes vulnerable to an eradication program. Anthelmintics have been used to exploit these constraints in past control programs and have lead to local eradication of several species of gastro-intestinal parasitic nematodes. Also, there are at present eradication programs for nematode parasites of human that are based on anthelmintic treatment. However, the suppressive pesticide treatment required to bring about the virtual elimination of species is a high-risk strategy and should only be undertaken if eradication is an achievable goal. It is also important to plan an exit strategy if eradication fails.     

Surveillance and risk management during the latter stages of eradication: experiences from Australia

The paper reviews the eradication of bovine tuberculosis from Australia with special reference to surveillance and managing the risk of animals exposed to tuberculosis infected animals during the latter stages of eradication. The successful eradication was based on a sound technical program with strong industry and government support. The model of joint industry and government funding and decision-making first used during the brucellosis and tuberculosis eradication campaign (BTEC) has been successfully incorporated within subsequent livestock disease control programs in Australia. An overview of the history of tuberculosis eradication in Australia provides a background to the surveillance approach. Australia was fortunate that there were no wildlife reservoir hosts. Feral animal reservoir hosts were removed during the eradication program. Surveillance to detect rare diseases is recognised to be statistically challenging with high resource requirements. Australian veterinary authorities have a high level of confidence that the combination of increasing sensitivity of abattoir surveillance systems by the submission of all granulomas detected at slaughter with increasing risk management of animals exposed to tuberculosis infected animals during the final stages of eradication provides a high level of assurance that Mycobacterium bovis has been eradicated.     

Antimicrobial susceptibility patterns of thermotolerant Campylobacter strains isolated from food animals in Ethiopia

Thermotolerant Campylobacter spp. are frequent causes of diarrhoea in humans worldwide mostly originating from poultry. It has been suggested that extensive veterinary use of antibiotics is largely responsible for resistance in human isolates. During a 4-month period from January to April 2004, 192 Campylobacter spp. were isolated from fecal samples of 485 healthy food animals. The in vitro susceptibility to 12 antibiotics was determined by the agar disk diffusion method. Among the 192 Campylobacter spp. isolated, 135 (70.3%) were identified to be C. jejuni, 51 (26.6%) were C. coli and 6 (3.1%) were C. lari. C. jejuni was the most prevalent species in chickens (80.8%) versus 16.2% C. coli and 3.0% C. lari. All isolates found in pigs were C. coli. All strains were sensitive to chloramphenicol and ciprofloxacin and all were resistant to cephalothin. More than 90% of the strains were sensitive to clindamycin, erythromycin, gentamicin, nalidixic acid, norfloxacin, streptomycin and tetracycline. Resistance was found against ampicillin in 20% and trimethoprim-sulphamethoxazole in 37.5%. Resistance was not statistically different among C. jejuni, C. coli and C. lari (p>0.05). Multidrug resistance to two or more drugs was detected in 14.5% of strains. In conclusion, the study showed that antimicrobial resistance is found only at relatively low frequencies for most antimicrobial agents tested except for ampicillin and trimethoprim-sulphamethoxazole. The low percentages of resistance to most antimicrobial agents tested in this study may be the result of low/no usage of these agents as a growth promoters or treatment in the Ethiopian animal farm setting. The detection of multidrug resistant isolates may pose a threat to humans and further limits therapeutic options.     

Associations of veterinary services and farmer characteristics with the prevalences of brucellosis and border disease in small ruminants in Spain

We investigated the farm factors associated with the prevalences of brucellosis and border disease (BD) in small-ruminant herds in the Madrid region of Spain. These infections were used as models of diseases of well-known and totally unknown distribution, respectively, to assess the association between the perception of the importance of a given disease on the relative contributions of veterinary services and the farmer's attitudes to its prevention. Sera, farming-management information and data concerning veterinary assistance and farmer characteristics were collected from 60 sheep or goat herds. The overall sero-prevalence of brucellosis was 5.7% (complement fixation) and for BD was 17.9% (ELISA test). The relationship between sero-positivity and the variables in the questionnaire was assessed by multivariable analysis using random-effects logistic-normal regression. ‘Availability of veterinary services' was a major protective factor for brucellosis. In contrast, no association with veterinary services was observed for BD, whereas ‘membership in a farmers' organization' (a variable associated with good farming practice and animal care) was a protective factor. ‘Membership of a farmers' organisation' and two other farmer variables indicative of good husbandry (‘youth' and ‘schooling') were associated with a lower sero-prevalence of brucellosis in univariable analysis but they did not remain significant in the multivariable model. Our observations suggest that veterinary-activity variables predominate over non-specific protective farm factors related to good husbandry in the case the disease is subject to disease surveillance. This underscores the importance of organized control programs for veterinary services to be effective in terms of animal disease prevention.     

Global veterinary leadership.

The public needs no reminder that deadly infectious diseases such as FMD could emerge in any country at any moment, or that national food security could be compromised by Salmonella or Listeria infections. Protections against these risks include the knowledge that appropriate and equivalent veterinary education will enable detection and characterization of emerging disease agents, as well as an appropriate response, wherever they occur. Global veterinary leadership is needed to reduce the global threat of infectious diseases of major food animal and public health importance. We believe that the co-curriculum is an excellent way to prepare and train veterinarians and future leaders who understand and can deal with global issues. The key to the success of the program is the veterinarian's understanding that there is a cultural basis to the practice of veterinary medicine in any country. The result will be a cadre of veterinarians, faculty, and other professionals who are better able (language and culture) to understand the effects of change brought about by free trade and the importance of interdisciplinary and institutional relationships to deal effectively with national and regional issues of food safety and security. New global veterinary leadership programs will build on interests, experience, ideas, and ambitions. A college that wishes to take advantage of this diversity must offer opportunities that interest veterinarians throughout their careers and that preferably connect academic study with intensive experiential training in another country. At its best, the global veterinary leadership program would include a partnership between veterinarians and several international learning centers, a responsiveness to the identified international outreach needs of the profession, and attention to critical thinking and reflection. The global veterinary leadership program we have described is intended to be a set of ideas meant to promote collaboration, coalitions, and discussion among veterinarians and veterinary educators who may be intrigued by the concept. The impact of the program can be summarized as follows: Outreach Programs: The global veterinary leadership program will establish new partnerships between veterinarians and veterinary college faculty as they supervise the international internships and see a relationship between their goals and the value of food safety to this country. Strategic Opportunity: The program will build on the critical role that US veterinarians and veterinary colleges already play in strengthening the safety of free trade in this hemisphere. Diversity in an Age of Specialization: The program will combine a global orientation, language ability, and access to comprehensive, research- and economic-related work/study opportunities to expose veterinarians to the expanding world market for veterinary expertise. New Linkages Through Corporate Partners: Through the success and high visibility of current research and education programs, most veterinary colleges are well positioned to engage industry, government, and university leaders in ways to use the proposed program to increase the flow of new ideas and talent into the world food enterprise. International Funding: A new partnership among veterinarians, industry, government, and university leaders can coordinate strong multilateral requests for funding from national and international sources. An Interdisciplinary Strategy that Benefits Veterinary Medicine: The program will combine the diverse veterinary research and education system with our strong national and international network of collaborators to provide globally competent veterinarians who will be needed for the corporate and public opportunities of the future.     

Pathogenicity of endophytic entomopathogenic fungi to Ornithodoros erraticus and Ornithodoros moubata (Acari: Argasidae)

The argasid ticks O. erraticus and O. moubata are of great medical and veterinary importance because they are vectors of the African swine fever virus and several species of human relapsing fever borreliae. Biocontrol of these ticks using entomopathogenic fungi has not been previously reported. We examined the pathogenicity to different developmental stages of these two argasids of six strains of the fungal species Beauveria bassiana (strains Bb1764 and Bb2157), Lecanicillium lecanii (strains Ll586, Ll618 and Ll3047) and Tolypocladium cylindrosporum (strain Tc3398). Three strains, Bb1764, Bb2157, and Tc3398, caused in Spanish O. erraticus mean mortality rates between 34.4% and 62% in 14-28 days post-inoculation. Additionally, Bb2157 also induced in African O. moubata mean mortality rates of 31.9%. The remaining strains caused lower mortality rates and were not considered effective. This is the first study in which some strains of entomopathogenic fungi are found to be effective against argasid ticks of the genus Ornithodoros, and its results might justify further efforts towards the application of entomopathogenic fungal strains as anti-argasid biocontrol agents.     

Bartonella and Babesia infections in cattle and their ticks in Taiwan

Bartonella and Babesia infections and the association with cattle breed and age as well as tick species infesting selected cattle herds in Taiwan were investigated. Blood samples were collected from 518 dairy cows and 59 beef cattle on 14 farms and 415 ticks were collected from these animals or in a field. Bartonella and Babesia species were isolated and/or detected in the cattle blood samples and from a selected subset (n = 254) of the ticks either by culture or DNA extraction, PCR testing and DNA sequence analysis. Bartonella bovis was isolated from a dairy cow and was detected in 25 (42.4%) beef cattle and 40 (15.7%) tick DNA samples. This is the first isolation of B. bovis from cattle in Asia and detection of a wide variety of Bartonella species in Rhipicephalus microplus. Babesia spp. were detected only on one farm from dairy cows either infected by Babesia bovis (n = 10, 1.9%) or B. bigemina (n = 3, 0.6%).     

Detection of bacterial contamination and DNA quantification in stored blood units in 2 veterinary hospital blood banks

Blood transfusions in veterinary medicine have become increasingly more common and are now an integral part of lifesaving and advanced treatment in small and large animals. Important risks associated with transfusion of blood products include the transmission of various infectious diseases. Several guidelines suggest what infectious agents to screen for in canine and feline transfusion medicine. However, while the risk of bacterial contamination of blood products during storage and administration has not been documented in veterinary medicine, it has emerged as a cause of morbidity and mortality in human transfusion medicine. Clinical experience shows that the majority of blood component bacterial contaminations are caused by only a few species. Unlike other types of bacteria, psychrotolerant species like Pseudomonas spp. and Serratia spp. can proliferate during the storage of blood units at 4°C from a very low titer at the time of blood collection to a clinically significant level (> 10⁵ CFU/mL) causing clinical sepsis resulting from red blood cell concentrate transfusions in human medicine. The purpose of this report was to describe the detection and quantification procedures applied in 4 cases of bacterial contamination of canine and feline blood units, which suggest the need for further investigations to optimize patients’ safety in veterinary transfusion medicine.     

Old problems on a new playing field: Helminth zoonoses transmitted among dogs, wildlife, and people in a changing northern climate

Although surveillance is limited, indigenous residents at latitudes ranging from 53 to 73°N in Canada appear to have a higher occurrence of infection with some zoonotic parasites than the general population. Conversely, they are relatively naïve to other zoonotic parasites that have previously been unable to establish at northern latitudes. For those parasites that circulate among dogs, wildlife, and people, potential risk factors in the North include limited availability of veterinary services, presence of free-roaming dog populations, and consumption of locally harvested fish and wildlife. These regions are also experiencing some of the greatest impacts of climate change in North America, including increased temperature, precipitation, and frequency and severity of extreme weather. We review the current taxonomy, genetic diversity, host and geographic distributions, epidemiology and risk factors for 3 genera of helminths (Diphyllobothrium spp., Echinococcus spp., and Toxocara sp.) in Canada's North in order to identify climate-sensitive aspects of their ecology. Free-living stages of parasitic zoonoses endemic in the Arctic (such as Diphyllobothrium dendriticum, the cervid strain of Echinococcus granulosus, and Arctic strains of Echinococcus multilocularis) will experience trade-offs between enhanced survival under wetter conditions and increased mortality under warmer conditions. Climate change might also lead to the introduction and establishment in the Arctic of parasitic zoonoses previously restricted to the sub-Arctic, such as Diphyllobothrium latum, Toxocara canis, and the prairie strain of E. multilocularis. Molecular techniques applied in broad geographic surveys are needed to address critical knowledge gaps in the geographic distribution, genetic diversity, and public health significance of zoonotic helminths already in the circumpolar North, and to determine the current barriers to range expansion of temperate-adapted parasites into the North. Dogs will continue to play important roles in the North, including that of a “bridging” host between sylvatic cycles and human communities. In a warming north, increased opportunities for business, agriculture, and tourism favor importation of dogs and their parasites into a newly suitable environment. Collaborations among veterinarians, public health personnel, and policy-makers are needed to enhance surveillance and mitigate for dog-transmitted parasitic zoonoses in a changing North.     

Molecular detection of zoonotic tick-borne pathogens from ticks collected from ruminants in four South African provinces

Ticks carry and transmit a remarkable array of pathogens including bacteria, protozoa and viruses, which may be of veterinary and/or of medical significance. With little to no information regarding the presence of tick-borne zoonotic pathogens or their known vectors in southern Africa, the aim of our study was to screen for Anaplasma phagocytophilum, Borrelia burgdorferi, Coxiella burnetii, Rickettsia species and Ehrlichia ruminantium in ticks collected and identified from ruminants in the Eastern Cape, Free State, KwaZulu-Natal and Mpumalanga Provinces of South Africa. The most abundant tick species identified in this study were Rhipicephalus evertsi evertsi (40%), Rhipicephalus species (35%), Amblyomma hebraeum (10%) and Rhipicephalus decoloratus (14%). A total of 1634 ticks were collected. DNA was extracted, and samples were subjected to PCR amplification and sequencing. The overall infection rates of ticks with the target pathogens in the four Provinces were as follows: A. phagocytophilum, 7%; C. burnetii, 7%; E. ruminantium, 28%; and Rickettsia spp., 27%. The presence of B. burgdorferi could not be confirmed. The findings of this study show that zoonotic pathogens are present in ticks in the studied South African provinces. This information will aid in the epidemiology of tick-borne zoonotic diseases in the country as well as in raising awareness about such diseases in the veterinary, medical and tourism sectors, as they may be the most affected.     

Identification,occurrence and clinical findings of canine hemoplasmas in southern Brazil

Hemoplasmas are ubiquitous pleomorphic and epicellular bacteria detected in erythrocytes in several species. In Brazil, studies on hemoplasmas have not included information on occurrence, clinical signs, and risk factors in dogs. This paper investigates the occurrence of hemoplasmas in dogs, focusing on risk factors and clinical status. Conventional PCR for the four types of canine hemoplasmas was performed in 331 blood samples collected from dogs clinically treated at a teaching veterinary hospital. Of all samples, 17/331 (5.1%) were positive for Mycoplasma haemocanis and 6/331 (1.8%) were positive for a ‘Candidatus Mycoplasma haemominutum-like’ organism. Risk factors included the presence of vectors, old age, dog bite wounds, and neoplastic diseases. In the multivariate analysis, a 4.40 odds ratio in dogs with vector-borne diseases indicated risk for hemoplasmosis. There was correlation between hemoplasma infection and neoplastic disease, suggesting that neoplastic conditions are a risk factor for hemoplasma infection in dogs.     

Role of pet dogs and cats in the transmission of helminthic zoonoses in Europe, with a focus on echinococcosis and toxocarosis

The close emotional tie between people and companion animals is a beneficial relation known as the human-animal bond. However, pet dogs and cats can play an important role in the transmission of helminthic zoonotic agents such as the tapeworms Echinococcus and the roundworms Toxocara which are directly transmitted from pets to the human environment without the involvement of vectors or intermediate hosts. In humans, echinococcosis has emerged in Europe and toxocarosis is still persisting in large endemic areas despite the availability of highly efficient anthelminthics for dogs and cats. Ecological changes significantly contributed to these trends: the high wild fox populations and the high density of freely roaming dogs and cats maintain a permanent infection pressure of these and other parasites. Further, the establishment of urban recreational environments closer to natural ecological systems boosted vole populations that represent urban reservoirs for zoonotic helminths. A good understanding of the parasites’ biology and epidemiology including the transmission to humans is required for planning and implementing effective prevention strategies. The continuous education of veterinarians and the information of the pet owners by providing uniform recommendations are of priority importance. A close collaboration between veterinary and public health professionals in a ‘One Health’ concept is required.     

The future of veterinary parasitology: a time for change?

The future of veterinary parasitology is discussed at a time when R&D funding from the pharmaceutical industry is declining, yet the opportunities for veterinary parasitologists to diversify their activities has never been greater. Emerging and re-emerging areas requiring input from veterinary parasitologists include: veterinary public health; conservation and wildlife diseases; emerging and exotic infectious diseases; surveillance strategies; economic effects of parasitic diseases; aquaculture; molecular epidemiology; dietary and biological control of parasitic diseases; animal welfare; organic agricultural systems; novel vaccination strategies; drug target characterisation and rational drug design. Without change, the survival of veterinary parasitology as a viable, distinct discipline is under threat. In this environment, veterinary parasitologists must be adaptable, imaginative and pro-active in terms of setting the agendas for establishing strategic alliances, promoting research needs and developing research programs.     

What veterinary practitioners should know about scrapie

Scrapie is the longest known and most widely spread of the transmissible spongiform encephalopathies and remains the model for much of the research regarding these diseases. Because scrapie is a reportable disease and the subject of an active eradication program in the United States, veterinary practitioners should have a basic understanding of the disease.     

Prevalence and characterization of Staphylococcus aureus and Staphylococcus pseudintermedius isolated from companion animals and environment in the veterinary teaching hospital in Zambia,Africa

The Republic of Zambia consists of only one veterinary teaching school at the University of Zambia (UNZA) where students and veterinarians are exposed to many bacterial pathogens including Staphylococcus aureus (SA) and Staphylococcus pseudintermedius (SP). The aim of this study was the characterization and antimicrobial susceptibility profile of eleven SA and 48 SP isolates from the veterinary hospitals’ in- and outpatients and the environment. No isolate was resistant to cefoxitin by disk diffusion test and the corresponding resistance gene mecA was not found. In contrast, the resistance rates of SA to penicillin (63.6%) and trimethoprim-sulfamethoxazole (36.4%) and SP to penicillin (52.1%) and tetracycline (25.0%) were the highest. A variety of sequence types (STs) without a predominant type including numerous novel types were determined, especially for SP (39.6%). The spa typing provided a clonal assignment for all SAs (100%) and 24 SPs (50%) with three and two novel types, respectively. This study has provided an overview of SA and SP in the veterinary teaching hospital at UNZA. However, for a better understanding of these species regarding pathogenesis and transmission, further studies on the prevalence and characterization of SA and SP from veterinary staff, pet owners, and farm animals in Zambia is needed.     

Epidemiological Aspects in the Leptospira spp. and Toxoplasma gondii Infection in Horses from Botucatu,São Paulo,Brazil

Leptospirosis and toxoplasmosis are zoonoses with high importance because of the economic and public health impact. This study was aimed to determine the seroprevalence of leptospirosis and toxoplamosis in 714 serum samples of horses from different farms from Botucatu, São Paulo, Brazil. The samples were researched for Toxoplasma gondii antibodies by indirect immunofluorescence antibody test (IFAT) and for Leptospira spp. antibodies by microscopic agglutination test. Of 714 serum samples, 128 (17.9%; 95% CI: 15.3%-20.9%) were positive for one or more serovars of Leptospira spp., with icterohaemorrhagiae, canicola, and castellonis as the most prevalent serovars, whereas 42 (5.9%; 95% CI: 4.4%-7.9%) were positive for T gondii, of which 33 samples (78.57%; 95% CI: 64.0%-88.2%) presented a titer of 16, 7 (16.7%; 95% CI: 8.4%-30.7%) a titer of 64, and 1 (2.38%; 95% CI: 0.6%-12.3%) a titer of 256. No significant difference was found among the results obtained and the associated variables such as age and sex.     

The role of final year extramural placements in the undergraduate veterinary curriculum

OBJECTIVE: To examine the role of a final year program of extramural placements in the undergraduate veterinary curriculum. DESIGN: An online questionnaire was made available to all students who completed the first lecture free final year of clinical placements offered by the Faculty of Veterinary Science, University of Sydney in 2004. The questionnaire collected information regarding the effectiveness of preparation for veterinary practice through: rating the usefulness of tasks and processes in achieving final year learning outcomes; collecting students' opinions on attributes vital to success as a veterinary practitioner and the value of extramural placements in developing these attributes; and rating the value of extramural placements in preparing students for veterinary practice. RESULTS: The most useful tasks or processes as evidenced by the percentage of students rating these tasks or processes as either very useful or useful were receiving feedback (80%) and completing case logs (78%). The main attribute considered vital to success as a veterinarian was communication skills and extramural placements were generally rated as very valuable in developing this competency. This program was considered to be particularly successful in facilitating the link between theory and practice, enabling the recognition and treatment of a range of diseases and developing interpersonal skills. CONCLUSION: The model for extramural placements implemented was generally regarded by students to be valuable in preparing them for veterinary practice.     

A new approach to teaching veterinary public health at the Ohio State University

Public-health practitioners with expertise in the area of veterinary public health are expected to understand the prevention and control of zoonotic infectious diseases in both human and animal populations. This focus on multiple species is what makes the veterinary public health (VPH) official unique. The development of a new VPH specialization within the existing Master of Public Health (MPH) degree program at the Ohio State University represents a significant new collaboration between the College of Veterinary Medicine and the College of Public Health. The main objective of the VPH specialization is to educate and train professionals to provide them with the skills, knowledge, and resources necessary to protect and improve human health using a One Medicine approach. The program targets a population of students who will likely enter the professional veterinary medicine curriculum but have one year available to enhance their preparatory training in health sciences before beginning the program. A core series of VPH courses was initiated to complement the existing MPH course requirements. The program has been successful in attracting students from the primary target population, but it has also attracted students wanting the MPH as a terminal degree and veterinarians returning to school to expand their career options.     

Veterinary and public health aspects of Toxocara spp

Pet dogs and cats can play an important role in the transmission of zoonotic nematodes such as Toxocara canis and Toxocara cati, by excreting eggs directly into the human environment, without the involvement of vectors or intermediate hosts. Human toxocarosis remains a hazard despite the availability of highly effective anthelmintics for dogs and cats. A good understanding of the biology and epidemiology of these parasites, and the risk factors that lead to their transmission to humans is required for effective prevention strategies. In this respect, the maintenance of high quality continuing education for veterinarians and the provision of suitably presented information to pet owners are of priority importance. A closer collaboration between veterinary and public health professionals within the ‘One Health’ concept is also required.