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At least 217 records · Page 12Linked to original sources

Immunodiagnosis of parasitic zoonoses: comparative efficacy of three immunofluorescence tests using antigens purified by affinity chromatography.

Three immunofluorescent antibody assays were developed during this study: the direct (DFAT) and indirect (IFAT) fluorescent antibody tests using frozen worm sections, and the cyanogen bromide indirect fluorescent antibody test (CNBr-IFAT) using helminth antigens purified by affinity chromatography bound on to commercially prepared CNBr-Sepharose 4B beads. Purified antigens used in the CNBr-IFAT gave greater specificity and sensitivity than either the DFAT or IFAT. Dirofilaria immitis, Toxocara canis, Angiostrongylus cantonensis and Ascaris lumbricoides infections were studied in natural and zoonotic hosts and in rabbits immunized with antigens prepared from these parasites. In addition, a serological survey of Aboriginal Australians from Queensland was made.

Animals↗

Immunodiagnosis and seroepidemiology of Angiostrongylus cantonensis zoonoses in man.

The development of serum and cellular assays to measure responses to Angiostrongylus cantonensis antigen, purified by affinity chromatography, formed the basis of this study. The specificity and sensitivity of these techniques were established in immunized rabbits and in naturally and laboratory-infected rats. The assays were then used to determine levels of immunological responsiveness to A. cantonensis in four Australian populations. There was a direct correlation between the prevalence of the parasite in rodents and the proportion of human reactors to A. cantonensis antigen in each population studied. Five patients with similar clinical histories and presenting symptoms suggesting eosinophilic meningitis were investigated; three were admitted to hospital. Haematological examination demonstrated hypereosinophilia in all five while three had, in addition, a cerebrospinal fluid eosinophilia. Serological tests and assays of cell-mediated responses to A. cantonensis antigen showed elevated immunological reactivity during the acute phase of illness with a subsequent decrease in reactivity corresponding with the progressive recovery of the patient.

Adult↗

Immunodiagnosis of parasitic zoonoses: sensitivity and specificity of in vitro lymphocyte proliferative responsiveness using nematode antigens purified by affinity chromatography.

The sensitivity of in vitro lymphocyte proliferative responsiveness using antigens purified by affinity chromatography, was greater than that of three serological tests and allowed the specific identification of Dirofilaria immitis, Toxocara canis, Angiostrongylus cantonensis and Ascaris lumbricoides in animals sensitized with parasite antigens, and the diagnosis of natural (D. immitis, T. canis and Angiostrongylus cantonensis) and zoonotic nematode infections. Lymphocytes remained viable in whole blood suspensions in RPM 1640 in a polystyrene insulation box at air temperature for at least 12 hours and reacted in the cell-mediated immunity test (CMIT) without loss of response. The CMIT proved useful in the early immunodiagnosis of nematode infections and showed that parasite antigens purified by affinity chromatography retained a high degree of specificity and sensitivity in both the CMIT and serological tests.

Animals↗

Arthropoda as zoonoses and their implications.

Some aspects of changing patterns of arthropodal infections and arthropod-borne diseases in Mediterranean areas are briefly discussed. Selected examples are given, with particular emphasis on the phenomenon of the synanthropic flea Ctenocephalides felis felis and on health problems caused by human infections with Argas reflexus, the common tick of urban pigeons in Europe. Finally, the risk of the emergence of Lyme borreliosis (Borrelia burgdorferi) is considered in relation to the increasing spread of environmental infestation with ticks, mainly Ixodes ricinus, an efficacious vector for the spirochaete.

Animals↗

Emerging infections in animals--potential new zoonoses?

It is well recognized that most emerging diseases of humans are zoonotic, and that the forces working to create emerging diseases in humans are also operating in animal populations. However, what is often overlooked is that emerging human diseases are usually preceded by the emergence of the same pathogen in an animal population. In fact, the developing disease in animals acts as a link allowing the disease to take hold and wreck havoc in public health. Numerous examples--Rift Valley fever, monkeypox, Nipah, and Ebola--serve to underscore this linkage and to highlight the increasing interconnectedness of animal and human health.

Animals↗

Molecular epidemiology: a multidisciplinary approach to understanding parasitic zoonoses.

Sound application of molecular epidemiological principles requires working knowledge of both molecular biological and epidemiological methods. Molecular tools have become an increasingly important part of studying the epidemiology of infectious agents. Molecular tools have allowed the aetiological agent within a population to be diagnosed with a greater degree of efficiency and accuracy than conventional diagnostic tools. They have increased the understanding of the pathogenicity, virulence, and host-parasite relationships of the aetiological agent, provided information on the genetic structure and taxonomy of the parasite and allowed the zoonotic potential of previously unidentified agents to be determined. This review describes the concept of epidemiology and proper study design, describes the array of currently available molecular biological tools and provides examples of studies that have integrated both disciplines to successfully unravel zoonotic relationships that would otherwise be impossible utilising conventional diagnostic tools. The current limitations of applying these tools, including cautions that need to be addressed during their application are also discussed.

Animals↗

Navigating parasite webs and parasite flow: emerging and re-emerging parasitic zoonoses of wildlife origin.

Wildlife are now recognised as an important source of emerging human pathogens, including parasites. This paper discusses the linkages between wildlife, people, zoonotic parasites and the ecosystems in which they co-exist, revisits definitions for 'emerging' and 're-emerging', and lists zoonotic parasites that can be acquired from wildlife including, for some, estimates of the associated global human health burdens. The paper also introduces the concepts of 'parasite webs' and 'parasite flow', provides a context for parasites, relative to other infectious agents, as causes of emerging human disease, and discusses drivers of disease emergence and re-emergence, especially changes in biodiversity and climate. Angiostrongylus cantonensis in the Caribbean and the southern United States, Baylisascaris procyonis in California and Georgia, Plasmodium knowlesi in Sarawak, Malaysia, Human African Trypanosomiasis, Sarcoptes scabiei in carnivores, and Cryptosporidium, Giardia and Toxoplasma in marine ecosystems are presented as examples of wildlife-derived zoonotic parasites of particular recent interest. An ecological approach to disease is promoted, as is a need for an increased profile for this approach in undergraduate and graduate education in the health sciences. Synergy among scientists and disciplines is identified as critical for the study of parasites and parasitic disease in wildlife populations. Recent advances in techniques for the investigation of parasite fauna of wildlife are presented and monitoring and surveillance systems for wildlife disease are discussed. Some of the limitations inherent in predictions for the emergence and re-emergence of infection and disease associated with zoonotic parasites of wildlife are identified. The importance of public awareness and public education in the prevention and control of emerging and re-emerging zoonotic infection and disease are emphasised. Finally, some thoughts for the future are presented.

Animals↗

Cryptosporidium and Giardia-zoonoses: fact or fiction?

Giardia and Cryptosporidium are enteric protozoan parasites that infect a wide range of vertebrate hosts. Both are transmitted either by direct faecal/oral contact or by the ingestion of contaminated food or water. The discovery of morphologically similar organisms infecting humans and a variety of mammals and birds has led to the proposal that both Cryptosporidium and Giardia are zoonotic (i.e. transmitted in nature between humans and animals). Transmission between humans and animals has been supported by cross-infection studies. However, closer examination of many of these studies reveals limitations in the methodologies utilised. More recent molecular genetic studies have demonstrated considerable genetic diversity among isolates of the same species of Giardia and Cryptosporidium, suggesting that these species are in fact species complexes and that some of these novel species may be host-specific. This paper will critically examine the evidence for the zoonotic transmission of these parasites.

Animals↗

Emerging helminth zoonoses.

As our ability to recognise and diagnose human disease caused by helminth parasites has improved, so our understanding of the epidemiology and clinical manifestations of these diseases has improved. Humans can develop patent infection with a wide range of helminth parasites, whose natural host is another vertebrate. Rather than focusing on a comprehensive review of zoonotic helminth infections, this review describes in detail examples of zoonotic helminth infections that have newly appeared in human populations, or have existed but are increasing in incidence or geographic range. Examples include intestinal capillariasis, anisakidosis, eosinophilic enteritis, oesophagostomiasis and gnathostomiasis. Potential reasons for the emergence of these infections, including changes in social, dietary or cultural mores, environmental changes, and the improved recognition of heretofore neglected infections often coupled with an improved ability to diagnose infection are discussed.

Animals↗

Emerging parasite zoonoses associated with water and food.

The environmental route of transmission is important for many protozoan and helminth parasites, with water, soil and food being particularly significant. Both the potential for producing large numbers of transmissive stages and their environmental robustness, being able to survive in moist microclimates for prolonged periods of time, pose a persistent threat to public and veterinary health. The increased demands on natural resources increase the likelihood of encountering environments and produce contaminated with parasites. For waterborne diseases, the protozoa, Cryptosporidium, Giardia and Toxoplasma, are the most significant causes, yet, with the exception of Toxoplasma, the contribution of zoonotic transmission remains unclear due to the absence of 'standardised' methods. The microsporidia have been documented in one waterborne outbreak, but the role of animals as the cause of contamination was not elucidated. In foods, surface contamination is associated with the faecal-oral pathogens, and some data are available to indicate that animal wastes remain an important source of contamination (e.g. cattle faeces and apple cider outbreaks), however, further work should focus on examining the source of contamination on fruit and vegetables. Increasing recognition of the burden of human fascioliasis has occurred; it is now recognised as an emerging zoonosis by the WHO. Toxoplasma, Trichinella and Taenia spp. remain important meatborne parasites, however, others, including Pleistophora-like microsporidians may be acquired from raw or lightly cooked fish or crustaceans. With increased international travel, the public health importance of the foodborne trematodiases must also be realised. Global sourcing of food, coupled with changing consumer vogues, including the consumption of raw vegetables and undercooking to retain the natural taste and preserve heat-labile nutrients, can increase the risk of foodborne transmission. A greater awareness of parasite contamination of our environment and its impact on health has precipitated the development of better detection methods. Robust, efficient detection, viability and typing methods are required to assess risks and to further epidemiological understanding.

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