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PubMed2000

Giardiasis as a re-emerging infectious disease and its zoonotic potential.

The reasons for considering giardiasis as a re-emerging infectious disease are presented, with emphasis on Giardia infections in child care centres, livestock and pets, and the role of zoonotic transmission. However, the aetiology and control of giardiasis is complicated by the genetic and phenotypic variability of Giardia species infective to mammals. Of particular significance has been the uncertainty about host specificity and the question of zoonotic transmission. The recent application of molecular characterisation procedures based on PCR has made an enormous contribution to an understanding of the genetic structure of Giardia populations, and this is reviewed in the context of the zoonotic transmission and molecular epidemiology of Giardia infections.

Adult↗
PubMed2004

The zoonotic potential of rotavirus.

Rotaviruses are generally species-specific, but cross-species transmission is possible, as has been demonstrated experimentally. Several case studies have indicated infection of humans by animal rotaviruses. Comparison of genetic sequences of human and animal rotaviruses often reveals close identity. Surveillance of circulating rotaviruses in the human population has revealed the presence of several uncommon genotypes. Many of these have been found in domestic animals, and it is possible that they arose in the human population through zoonotic transmission. The low incidence of uncommon strains would suggest that such transmission, or at least the establishment of an animal rotavirus or a human/animal reassortant virus in the human population, does not happen with any great frequency. However, many millions of people will be exposed year on year to animal rotaviruses. This happens within farming communities, and potentially to visitors to the countryside. There may be some measure of environmental contamination through livestock excrement. This exposure may not result in high levels of infection, but some infection could occur. There may be a continual input of rotavirus strains or sequences into the human population from the animal population albeit at a very low level.

Animals↗
PubMed2002

Presence of human Giardia in domestic, farm and wild animals, and environmental samples suggests a zoonotic potential for giardiasis.

Giardia lamblia which parasitize humans belong to either of two genotypes, A or B, based on specific signature sequences in the 5' end of the small subunit (16S) ribosomal RNA (rRNA) gene. These two genotypes also were found in cysts from fecal samples of animal origin such as dogs, cats, some farm animals and wild animals. In addition, trophozoites recovered from cysts obtained from environmental samples belonged to these two genotypes as well, suggesting that the G. lamblia genotypes A and B are widespread and possibly zoonotic. Trophozoites were recovered from rats and these isolates might belong to another genotype of G. lamblia. Deer mice and one dog appeared to be parasitized by genotypes of Giardia with close affinity to G. microti. This species, therefore, also consists of a genotype complex.

Animals↗
PubMed2002

[Chlamydial diseases of domestic animals--zoonotic potential of the agents and diagnostic issues].

The role of chlamydiae as agents of a number of important animal and human diseases is still the subject of intensive research. Recently, a proposal for taxonomic reclassification of this group of obligate intracellular bacteria was published, which was based on a large amount of new data on genetic relatedness. According to this proposal, the family Chlamydiaceae now comprises two genera (Chlamydia and Chlamydophila) with 9 largely host-related species. The previously accepted classification scheme had distinguished 4 species within the genus Chlamydia. The most important animal chlamydiosis with zoonotic character is psittacosis, a systemic disease in psittacine birds of acute, protracted, chronic or subclinical manifestation. The analogous infection in domestic and wild fowl is known as ornithosis. Avian strains of C. psittaci (new classification: Chlamydophila psittaci) can also infect humans, the symptoms being mainly unspecific and influenza-like, but severe pneumonia, endocarditis and encephalitis are also known. The main group of persons facing an elevated risk of infection includes those having frequent contact with domestic and companion birds at work or in their spare time. In Germany, the annual average of notified cases is approximately 100. Cases of transmission to humans were repeatedly reported in connection with enzootic abortion in sheep (causative agent: C. psittaci or Chlamydophila abortus, respectively). Various chlamydial species occur as pathogens and commensals as well in cattle, pigs, horses, and cats. The assessment of the actual epidemiological importance is, however, often difficult because of their almost ubiquitous spread. Likewise, those strains of C. pneumoniae (new classification: Chlamydophila pneumoniae) found in several animal species can not yet be assessed for pathogenic properties. The possibilities for diagnostic detection of chlamydiae have considerably improved following the introduction of molecular methods, particularly the polymerase chain reaction (PCR), which permits direct identification from clinical specimens and differentiation of species.

Animals↗
PubMed2001

Zoonotic potential of Enterocytozoon bieneusi.

The reservoirs and the modes of transmission of the most frequent microsporidial species in humans, Enterocytozoon bieneusi, are still unknown. We have examined fecal samples of 26 humans and 350 animals from 37 species to find 18 samples containing this parasite from humans, cats, pigs, cattle, and a llama. Genotypic characterization of the internal transcribed spacer of the rRNA gene resulted in 14 different genotypes, 6 of them previously undescribed. Phylogenetic analysis revealed the lack of a transmission barrier between E. bieneusi from humans and animals (cats, pigs, and cattle). Thus, E. bieneusi appears to be a zoonotic pathogen.

Animal Diseases↗
PubMed2003

Triosephosphate isomerase gene characterization and potential zoonotic transmission of Giardia duodenalis.

To address the source of infection in humans and public health importance of Giardia duodenalis parasites from animals, nucleotide sequences of the triosephosphate isomerase (TPI) gene were generated for 37 human isolates, 15 dog isolates, 8 muskrat isolates, 7 isolates each from cattle and beavers, and 1 isolate each from a rat and a rabbit. Distinct genotypes were found in humans, cattle, beavers, dogs, muskrats, and rats. TPI and small subunit ribosomal RNA (SSU rRNA) gene sequences of G. microti from muskrats were also generated and analyzed. Phylogenetic analysis on the TPI sequences confirmed the formation of distinct groups. Nevertheless, a major group (assemblage B) contained most of the human and muskrat isolates, all beaver isolates, and the rabbit isolate. These data confirm that G. duodenalis from certain animals can potentially infect humans and should be useful in the detection, differentiation, and taxonomy of Giardia spp.

Animals↗
PubMed1981

The zoonotic potential of bovine leukemia virus.

Many workers have investigated the possibility that bovine leukemia virus (BLV) might be transmissible to man. The epidemiological studies were designed to examine for associations between human leukemia and a rural environment, cattle farming, veterinary activities, or bovine leukosis. The serological studies were used to test serum samples from human cancer patients and from persons with potential occupational exposure to BLV, among others, for evidence of BLV antibodies. All these studies are critically reviewed. It is concluded that there is no epidemiological or serological evidence from human studies to indicate that BLV can infect man.

Animals↗
PubMed2004

Molecular characterization of Enterocytozoon bieneusi in cattle indicates that only some isolates have zoonotic potential.

In this study, 338 fecal samples were analyzed for Enterocytozoon bieneusi from cattle farms in Florida, Maryland, Michigan, New York, North Carolina, Pennsylvania, Virginia, and Portugal. The internal transcribed spacer region (392 bp) of the rRNA gene of E. bieneusi was amplified using a nested PCR protocol. Thirty-two E. bieneusi-PCR positive samples were sequenced. A high degree of genetic polymorphism, represented by five distinct genotypes (BEB1-BEB5), was found among the E. bieneusi isolates from cattle. Most of the isolates formed a distinct cluster consisting of only the four cattle genotypes, but six isolates of a genotype clustered together with E. bieneusi genotypes from humans and other domestic animals. Therefore, only some E. bieneusi isolates from cattle may be of public health importance.

Animals↗
PubMed2004

Genetic heterogeneity at the beta-giardin locus among human and animal isolates of Giardiaduodenalis and identification of potentially zoonotic subgenotypes.

Human giardiasis, caused by the intestinal flagellate Giardia duodenalis, is considered a zoonotic infection, although the role of animals in the transmission to humans is still unclear. Molecular characterisation of cysts of human and animal origin represents an objective means to validate or reject this hypothesis. In the present work, cysts were collected in Italy from humans (n=37) and animals (dogs, one cat and calves, n=46), and were characterised by PCR amplification and sequencing of the beta-giardin gene. As expected, only Assemblages A and B were identified among human isolates. The host-specific Assemblages C and D were found in the majority of dog isolates; however, 6 dog isolates were typed as Assemblage A. The cat-specific Assemblage F has been identified in the single feline isolate available. Among calf isolates, most were typed as Assemblages A (n=12) and B (n=5), whereas the host-specific Assemblage E was rarely found (n=3). Sequence heterogeneity in the beta-giardin gene allowed a number of subgenotypes to be identified within Assemblage A (8 subgenotypes), B (6 subgenotypes), D (2 subgenotypes), and E (3 subgenotypes). Five of these subgenotypes, namely A1, A2, A3, A4 and B3, were found to be associated with infections of humans, of dogs and of calves; these data, therefore, supported the role of these animals as a source of infection for humans.

Animals↗
PubMed1997

PCR-based methods for identification of potentially zoonotic ascaridoid parasites of the dog, fox and cat.

Genomic DNA was extracted from ascaridoid nematodes collected from dogs, foxes and cats. A region spanning the second internal transcribed spacer (ITS-2) of the ribosomal DNA of each sample was amplified by PCR. Representative ITS-2 products for each nematode species (Toxocara canis, Toxocara cati and Toxascaris leonina) were sequenced. Restriction sites were identified for use as genetic markers in a PCR-linked RFLP assay. The three species could be differentiated from each other and from other ascaridoids that may be found in human tissues by use of two endonucleases, HinfI and RsaI. Primers were designed to unique regions of the ITS-2 sequences of the three species for use in diagnostic PCR procedures and primer sets evaluated against panels of homologous and heterologous DNA samples. Results suggest that both methods are good candidates for further development for the detection and/or identification of ascaridoid larvae in human tissues.

Animals↗
PubMed1997

Zoonotic potential of infection with Fasciola spp. by consumption of freshly prepared raw liver containing immature flukes.

Mice were successfully infected with metacercariae of the Japanese Fasciola sp., resulting in the recovery of a mean number of 110 live immature flukes per mouse 4-5 days after inoculation. Twenty-four mice were then inoculated orally, each with a mean number of 68 freshly recovered immature flukes. The livers of 7 of the 24 recipient mice showed migratory lesions of capsular and subcapsular granulomatous infiltration and 2 of those mice also had haemorrhagic lesions. The lesions were typical of those caused by active migration of early immature flukes. However, no flukes were found in the livers of the recipient mice at necropsy when the flukes were aged 14 weeks. In another experiment, 10 piglets were given fresh livers of mice harbouring approximately 2000 live immature flukes aged 3-7 days. Two additional piglets were inoculated with 2000 metacercariae of Fasciola. All pigs were killed when the flukes were 14 days old. Granulomatous lesions were present in all pigs, except in those that were given livers containing flukes aged 7 days. The lesions were localized, forming well-defined foci, different from the typical migratory lesions normally observed in mouse or sheep liver at the early stage of fluke migration. From the 10 pigs given livers, 65 live flukes were recovered at necropsy, 0.29% of the estimated number of immature flukes given. From the 2 pigs which received 2000 metacercariae each, a total of 198 flukes were recovered (5%). The results of the experiments suggest that humans consuming raw liver dishes prepared from fresh livers infected with immature Fasciola spp. could become infected with liver fluke.

Animals↗
PubMed1998

Characterisation of anisakid nematodes with zoonotic potential by nuclear ribosomal DNA sequences.

Larvae of three species of anisakid nematode from fish, Anisakis simplex, Hysterothylacium aduncum and Contracaecum osculatum, were characterised genetically using a molecular approach. The nuclear ribosomal DNA region spanning the first internal transcribed spacer, the 5.8S gene and the second internal transcribed spacer was amplified and sequenced. The lengths of the first and second internal transcribed spacer sequences of the three species ranged from 392 to 449 bp and 262 to 347 bp, respectively, whereas the 5.8S sequence was 157 bp. For the three species, the G+C contents for the three regions of ribosomal DNA ranged from 42.4 to 52.2%. While no intraspecific variation was detected in the second internal transcribed spacer or 5.8S sequence of any species examined, one polymorphic nucleotide position was detected in the first internal transcribed spacer sequence for A. simplex and H. aduncum. The extent of sequence differences in the first (approximately 34-45%) and second (approximately 50-53%) internal transcribed spacers among the species was greater than in the 5.8S gene (approximately 3-5%). Based on the sequence differences, PCR-based restriction fragment length polymorphism and single-strand conformation polymorphism methods were established for the unequivocal delineation of the three species. These methods should provide valuable tools for studying the life-cycle, transmission pattern(s) and population structure of each of the three anisakid nematodes examined herein, and for the diagnosis of anisakiasis in humans and animals.

Animals↗
PubMed1987

The zoonotic potential of feline leukemia virus.

The many studies that have addressed the possibility for FeLV infection in human beings are reviewed in this article. Because of the many similarities between FeLV-induced immune system impairment in cats and retrovirus related acquired immune deficiency syndrome in man, these two conditions are discussed as well.

Animals↗
PubMed2001

An examination of risk factors associated with beef cattle shedding pathogens of potential zoonotic concern.

The prevalence of three waterborne zoonotic pathogens (Campylobacter sp., Giardia sp. and Cryptosporidium parvum) in rectal faecal samples from a random sample of adult beef cattle was determined. Management factors that may be associated with shedding of these organisms were examined. For Campylobacter sp. prevalence was 5.0%, and the number of females on the farm was positively associated with the proportion that tested positive. For Giardia sp. prevalence was 6.5%, and none of the management factors examined was significantly associated with the proportion in a herd testing positive. C. parvum was identified in 1.1% of samples. The length of calving season and whether any procedures were performed on the calves in the first 2 days of life were positively associated with the proportion that tested positive. We conclude that this sample of adult beef cattle represent a relatively limited threat to water supplies and subsequent disease transmission to humans from these pathogens.

Animals↗
PubMed2002

High resolution genotyping of Campylobacter jejuni strains by macrorestriction analysis with XhoI and polymerase chain reaction targeting enterobacterial repetitive intergenic consensus sequences: can we predict the zoonotic potential of strains?

Campylobacter jejuni isolates of human, canine, feline, bovine and poultry origin were investigated for their genomic diversity using O-antigen typing (n = 271), SmaI (n = 158) and XhoI (n = 158) macrorestriction analysis and ERIC-PCR (n = 107). The O-antigens O:1/44, O:2, O:4 complex, O:37. O:40 were identified and 53.7% of the human and 56.1% of the animal strains were typable with the available antisera. Two ERIC-PCR pattern groups were generated representing human and animal strains as well as those exclusively of animal origin. XhoI macrorestriction analysis also distinguished 'human' and 'non-human' strain clusters, but by SmaI restriction mainly serotype-associated clusters were found. In conclusion, genomic differences may occur between 'human' and 'non-human' strains and this may reflect their potential to overcome the barrier from animals to humans.

Animals↗