| Cryptosporidium, microsporidia and Cyclospora have been recognized as emerging en-teric parasites, and Giardia is considered as a kind of re-emerging enteric parasite. Thus far,over 90% of the waterborne disease outbreaks have been caused by these four parasites. These parasites are able to infect human as well as many kinds of animals. Therefore, evaluating the human infection potential of these parasites originated from animals is of major public health significance. In this study, species/genotypes/subtypes of these parasites from non-human primates, sheep and wildlife animals were determined in order to assess the human infection potential and potential waterborne transmission after comparing with those commonly found in humans and water. These particular animals were chosen because: 1) Nonhuman primates were genetically close to human, and were more likely to be the animal sources for transmit-ting anthroponotic diseases to humans; 2) The farm sheep infected by Cryptosporidium or Gi-ardia may cause infection to farmers and visitors in addition to cause huge economic losses; 3)It is still unclear of the public health significance of Giardia infecting wildlife.In this study, 411 fecal specimens from rhesus monkeys in Qianling Park and 23 water samples nearby were collected. The results showed that: 1) The infection rates of these four parasites in rhesus monkeys were all high, with Cryptosporidium 10.9% (45/411), Giardia 8.5% (35/411), Enterocytozoon bieneusi 28.2% (116/411) and Cylcospora 6.6% (27/411). 2)The infection rates were positively correlated with the animal density, implying that close contact of animals may facilitate the transmission of these diseases. 3) Except for Cyclospora,the majority of the species and subtypes of Cryptosporidium, including C. hominis (39), C.parvum (5) and C. felis (1), Giardia, including genotype A (10) and B (25), and Enterocyto-zoon bieneusi, including Peru11 (69), Type? (6), WL15 (28) and Ebpc (4) were all human-pathogenic in nature. 4) The infection rates of Cryptosporidium, Giardia, E. bieneusi and Cy-clospora were 47.8%, 52.2%, 56.5% and 21.7%, respectively, in the 23 water samples, and the genotypes and subtypes of the four parasites in water were identical to those found in rhe-sus monkeys. The high infection rate, presence of human-pathogenic species and contamina-tion of water indicated that the pathogens infecting rhesus monkeys is of important public health significance to human and other animals, and there is a certain chance to cause water-borne outbreaks.In order to verify the association of infection and animal density, we compared the infec-tion of these pathogens in 205 laboratory Macaca fascicularis in three groups, with group 1 including 168 juveniles kept individually, group 2 including 18 juveniles raised in group, and group3 including 19 adults raised in groups. The results showed that: 1) The infection rates of Giardia and E. bieneusi were correlated with the animal density, with the infection rates in group 2 (11.3% and 72.2%) significantly higher than those in group 1 (1.2% and 11.3%, P <0.05). This confirmed that the animal gathering improved the transmission risk of these dis-eases. 2) Juvenile monkeys kept in groups (Group 2) had significantly higher infection rate(72.2%) of E. bieneusi than adult moneys kept in groups (Group 3) (31.6%, P = 0.01), while the infection rates of other parasites did not show any correlation with ages. 3) These labora-tory monkeys were also infected by human-pathogenic species and genotypes, including an-throponotic IdA14 (1), zoonotic Giardia assemblage A (2) and B (3), and zoonotic E. bie-neusi genotypes D (16), Peru11 (2), WL (1), Macaque3 (15) and Macaque4 (2).To understanding the public health significance caused by Giardia and Cryptosporidium infecting farm sheep, we genotyped both pathogens in lambs and ewes at parturition. The re-sults showed that: 1) High infection of Cryptosporidium (13.1%) was found, and one of the two dominant species,C. biquitum,was a new emerging species infecting humans. 2) Alt-hough the overall infection rate of Giardia (4.3%) was lower, the risk for causing public health problems of the Giardia in lambs (8.6%) was higher than that in sheep (0.94%). In ad-dition, all the genotypes belonged to zoonotic assemblage A. 3) C. xiaoi was the dominant species in lambs aged 3-4 weeks (15/16) and 15-16 weeks (6/20), and was also the dominant species in ewes in perparturient period (9/12). This indicated that ewes in perparturient period were the source of Cryposporidium to lambs. 4) Both Cryptosporidium and Giardia geno-types infecting lambs may cause waterborne transmission.To verify whether Giardia in wildlife could pose threat to public health via waterborne transmission,197 fecal specimens from 25 species of wildlife and 73 nearby water samples from 15 watershed sites were collected and subjected to genotyping using three loci (tpi, bg and gdh). The results showed that: 1) A few wildlife species were reservoirs of zoonotic Gi-ardia genotype A and B, which may pose risk to public health. 2) All of the 15 watershed sites were contaminated by Giardia and the majority of the Giardia genotypes in water were identical to those in animals. 3) PCR amplification of water samples showed 60.2% positive(44/73), with tpi owned highest sensitive, followed by P-giardin (35.6%, 26/73) and gdh(24.7%,18/73). Based on this,multi locus genotyping should be widedly used in the public health evaluation of Giardia. This study means that Giardia infecting animals can contami-nate source water, and cause potential risk to public health.The results of this study provided theoretic basis for evaluating the waterborne disease risk caused by some animals. It would also facilitate the strategy-making for the correspond-ing diseases. |
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