[Prevalence of Echinococcus infections in wild carnivores based on copro - DNA tests in Serthar County of Sichuan Province]

OBJECTIVE

To investigate the prevalence of Echinococcus infections in wild carnivores in Serthar County, Sichuan Province, so as to provide insights into echinococcosis control in local areas.

METHODS

Stool samples were collected from wild carnivores in Serthar County, Sichuan Province in May 2021, and the host sources of stool samples and Echinococcus infections were identified using PCR assays. The prevalence of E. multilocularis, E. granulosus and E. shiquicus infections was estimated in different hosts.

RESULTS

A total of 583 stool samples were collected from wild carnivores, including 147 stool samples from fox, 154 from wolf, 227 from wild dogs and 11 from lynx. The overall prevalence of E. multilocularis, E. granulosus and E. shiquicus infections was 5.68%, 0.19% and 14.20% in canine stool samples, and no E. granulosus infection was detected in fox stool samples, while the prevalence of E. multilocularis and E. shiquicus infections was 0.68% and 47.62% in fox stool samples (χ2 = 88.41, P < 0.001). No E. granulosus or E. shiquicus infection was detected in wolf stool samples, and the prevalence of E. multilocularis infection was 10.39% in wolf stool samples. The prevalence of E. multilocularis, E. granulosus and E. shiquicus infections was 5.73%, 0.44% and 2.20% in canine stool samples (χ2 = 12.13, P < 0.01). In addition, the prevalence of E. multilocularis infections was significantly higher in wolf stool samples than in canine and fox stool samples (χ2 = 13.23, P < 0.01), and the prevalence of E. shiquicus infections was significantly higher in fox stool samples than in canine and wolf stool samples (χ2 = 187.01, P < 0.001). No Echinococcus infection was identified in 11 lynx stool samples.

CONCLUSIONS

The prevalence of Echinococcus infections is high in wild canines in Serthar County, Sichuan Province. Wolf, wild dog and fox all participate in the wild life cycle of E. multilocularis in Serthar County, and wolf and wild dogs may play a more important role.

Simple modification to improve reliability of copro-DNA examinations for diagnosing Echinococcus multilocularis infections in red foxes

Epidemiological studies of Echinococcus multilocularis infections in definitive hosts require a reliable and economic diagnostic method. In this study, the current copro-DNA examination technique was modified by increasing the faecal amounts tested and adding a step to neutralize the faeces before DNA extraction. Reliability of the modified method was evaluated using rectal faecal samples from red foxes and comparing them with intestinal worms detected using the sedimentation and counting technique (SCT) following necropsy. The modified copro-DNA examination method demonstrated 93.9% sensitivity (138/147) on the SCT. Its detectability increased depending on the worm burden, and the sensitivity was 100% in cases harbouring over 1000 worms. From 111 SCT-negative cases, six (5.4%) were copro-DNA-positive, and all were confirmed as E. multilocularis via sequencing analysis. Five of the remaining 105 SCT-negative cases (4.8%) retained polymerase chain reaction (PCR) inhibitors in the extracted solution, suggesting that approximately 5% of the red fox faeces retained these inhibitors after treatment with the present copro-DNA extraction method. Although further evaluation is needed for faeces deposited in the wild, the present copro-DNA examination technique will help monitor the E. multilocularis prevalence in definitive hosts. When used for detailed evaluations of endemicity (e.g. changes in infection pressure or spread in non-endemic areas), the absence of PCR inhibitors should be confirmed, and multiple trials on faecal subsamples are recommended.

A PCR-RFLP assay for discrimination of Echinococcus granulosus sensu stricto and Taenia spp. in dogs stool

In order to develop a method of identification and discrimination of Echinococcus granulosus sensu stricto from faecal samples of dogs infected with taeniid eggs (Echinococcus spp., Taenia spp.), a combined strategy of Polymerase Chain Reaction (PCR) and Restriction Fragments of Lenght Polymorphisms (RFLP) was proposed. Initially, a pair of primers was designed to amplify a fragment of the 12 Subunit of ribosomal RNA gene (12SrRNA) from mitochondrial DNA. The amplified product was digested by SspI restriction enzyme, which in E. granulosus kept the intact fragment of 160 basis pairs (bp), while in Taenia spp. produced two fragments (62 bp and another of 98 bp). The method was tested using positive controls of DNA, in faecal samples experimentally contaminated with eggs of E. granulosus and Taenia spp. and in dogs naturally infected. In all of them, reproducible results were obtained and the primers were specific to amplify only Taeniidae DNA. The sensitivity of the technique was tested, achieving amplification of DNA extractions with a single egg. In conclusion, the technique developed was optimal and easy to identify patent infections by E. granulosus s.s., constituting a possible alternative for epidemiological studies in dogs, especially in endemic areas where this infection occurs.

Diagnostic biomarkers in murine Cryptosporidiosis: dose- and age-related infection

Increasing prevalence of Cryptosporidium raises the importance to explore different aspects of its infection. In the absence of reproducible in vitro culturing, animal model is the only experimental method to study Cryptosporidium. Our study evaluated Cryptosporidium infection using coproscopy, copro-antigen and copro-DNA for early detection of murine cryptosporidiosis. Hundred and forty albino mice (neonates and adult) were divided into two groups, control group received sterile PBS solution, and infected groups were inoculated with molecularly characterized Cryptosporidium parvum oocysts and further subdivided into three subgroups for infectious dose response detection. Mice fecal samples were collected every 4 h on the first day and then daily and examined for fecal oocysts, copro-antigen and copro-DNA. Four mice from each subgroup were killed at 12, 24 and 48 h post-infection (P-I), and their intestines were examined for cryptosporidial mucosal DNA. Cryptosporidium copro-antigen and copro-DNA were detected 4 and 8 h P-I in infected neonatal and adult mice, respectively, and intestinal mucosal DNA was detected after 12 h in both. Microscopy was able to detect oocysts 48 h P-I. Inoculated C. parvum oocysts were recovered in feces of infected mice without genotypic changes. Neonate mice showed higher susceptibility for cryptosporidial infection than adults without statistical differences for the given infectious doses. Both copro-immunoassay and copro-nPCR assays can early detect Cryptosporidium infection; however, nPCR was able to identify Cryptosporidium species, making nPCR a reliable biomarker for early detection in murine model.

Molecular detection of giardiasis among children at Cairo University Pediatrics Hospitals

Giardiasis is a prevailing intestinal disease in children. This study aimed to determine molecular prevalence of Giardia intestinalis in children attending Cairo University Pediatrics Hospitals, using copro-PCR assays, conventional methods and to evaluate diagnostic effectiveness of used tests. 229 fecal samples were collected from children suffering from gastrointestinal symptoms and examined for Giardia by microscopy, Immuno-chromatographic test (ICT), copro-DNA using two PCR assays targeting tpi [nested-PCR (nPCR)] and 18S [conventional-PCR (cPCR)] genes. Out of 229 samples assessed, Giardia was diagnosed in 13.9, 17, 17.9, 4.8 % of cases using microscopy, ICT, nPCR (tpi) and cPCR (18S), respectively. Nominating both PCR assays as composite reference standard, microscopy and ICT were of reliable specificity (100 and 96.9 %) and accuracy (95.6 and 93.6 %) but of limited sensitivity (78.6 and 76.2 %). Kappa agreement showed, there was substantial agreement of ICT (0.776) and almost perfect agreement of microscopy (0.839) with PCR assays. Giardia showed a molecular prevalence of 18.3 % (42/229). ICT assay for Giardia surpassed microscopy but both couldn't be used as a consistent single detection method due to their lowered sensitivities. nPCR targeting tpi is a reliable diagnostic test aiding to determine true prevalence of Giardia.

Molecular detection of Capillaria philippinensis: An emerging zoonosis in Egypt

Human infection with Capillaria philippinensis is accidental; however, it may end fatally if not diagnosed and treated in the proper time. The first case was detected in the Philippines in 1963, but later reported in other countries around the world, including Egypt. In this report, molecular diagnosis using a specific nested PCR for detection of C. philippinensis in faeces is described based on the amplification of small ribosomal subunit. The test showed sensitivity and specificity, as it detected all the positive cases and gave no cross-reaction with human DNA and DNA of other tested parasites. This method can be very useful not only for improvement of diagnosis, but also to understand the different environmental routes of transmission by detection of C. philippinensis DNA-stages in the possible fish intermediate hosts and reservoir animal host, helping to improve strategies for surveillance and prevention of human disease.

Laboratory utility of coproscopy, copro immunoassays and copro nPCR assay targeting Hsp90 gene for detection of Cryptosporidium in children, Cairo, Egypt

Cryptosporidium is a significant cause of diarrhea worldwide especially in children. Infection may end fatally in immunocompromised patients. Multi-attribute analysis was used to determine the lab utility of 4 diagnostics; coproscopy of AF stained fecal smear, fecal immunoassays by ICT and ELISA and copro-nPCR assay targeting Hsp90 gene, for detection of Cryptosporidium in stool of 250 Egyptian children (150 diarrheic and 100 non-diarrhaeic children). Also, to determine Cryptosporidium molecular prevalence. Cryptosporidium was an important enteric pathogen among both diarrheic and non-diarrheic study children with a clearly high prevalence of 16.4 % (n = 41). Conventional methods had perfect specificity (100 %) but couldn`t be used as a consistent single detection method due to their lowered sensitivities. Multi-attribute analysis ranked nPCR the highest test for lab use. Being the test with the best diagnostic yield, nPCR is a reliable diagnostic test and is going to replace conventional methods for reliable detection of Cryptosporidium.

Differential Detection of Echinococcus Spp. Copro-DNA by Nested-PCR in Domestic and Wild Definitive Hosts in Moghan Plain, Iran

BACKGROUND

Despite Echinococcus granulosus, there are merely two old reports of E. multilocularis infection among Iranian canids of Moghan Plain, the only area known endemic for the species. We detected specific DNA markers in fecal samples by PCR (Copro-PCR) for differential diagnosis of Echinococcus species in living canids.

METHODS

Totally 144 fecal samples from domestic dogs, red foxes and a golden jackal were examined for genus-specific Echinococcus coproantigens using ELISA. Forty two positive or ambiguous samples were further examined for Echinococcus species-specific DNA markers by two different set of nested-PCR.

RESULTS

Twenty five out of 144 (17.4%) animals were contaminated with E. granulosus including 14 (23.7%) domestic dogs, 10 (11.9%) red foxes and one (100%) golden jackal. But none of them harboured E. multilocularis species-specific Copro-DNA. The overall prevalence of E. granulosus and E. multilocularis infections in canids of the area was estimated to be 17.4% and 0.0%, respectively. There was a significant relation between the results of Copro-PCR and CA-ELISA.

CONCLUSION

The lack of E. multilocularis infection, compared to previous reports may be due to the differences in used diagnostic methods and/or recently limited territories of wild canids and altered their food resources in this particular area.

Molecular Diagnosis of Strongyloides stercoralis Infection by PCR Detection of Specific DNA in Human Stool Samples

BACKGROUND

Strongyloidiasis is mostly an asymptomatic infection and diagnosis of latent infections is difficult due to limitations of current parasitological and serological methods. This study was conducted to set up a PCR-based method for molecular diagnosis of Strongyloides stercoralis infection by detection of copro-DNA in stool samples.

METHODS

A total of 782 fresh stool samples were collected and examined by agar plate culture. Among those sixteen stool samples, which confirmed to be infected with S. stercoralis were examined as positive control to set up each single and nested PCR, using two primer sets designing to amplify partial ribosomal DNA of S. stercoralis genome. Since, single PCR method yielded higher efficacy in detecting positive samples, in the second step, 30 stool samples, which found negative for S. stercoralis by agar plate culture of single stool sample, were examined by single PCR. Data analysis was performed using McNemar's χ(2) test, with consideration of a P-value of <0.05 as indication of significant difference.

RESULTS

In amplification of DNA extracted from stool samples, single PCR detected S. stercoralis DNA target in all 16 positive samples, while nested PCR amplified DNA in only 75% of samples. In the second step, single PCR amplified S. stercoralis extracted DNA in 5 out of 30 samples which were negative by coproculture.

CONCLUSION

Single PCR method amplifying a short (100bp) target represented more efficacies for detection of S. stercoralis in faecal examination compared to agar plate culture and nested PCR, which amplified longer target.