Molecular and serological diagnosis of Toxoplasma gondii infection in experimentally infected chickens

Molecular detection of Toxoplasma gondii in Tunisian free-range chicken meat and their offal

Free-range chickens are infected by Toxoplasma gondii (T. gondii) mainly when they pick-up their food from the ground. The present study was performed to estimate the molecular prevalence of T. gondii in free-range chicken meat (breast and thigh muscles) and their offal (heart and gizzard). The molecular characterization and the phylogeny of T. gondii amplicons were also investigated. Two PCRs were compared, the first targeting B1 gene and a nested PCR targeting the internal transcribed spacer ITS-1 gene. Among the 60 tested birds, 47 free-range chickens had at least one positive PCR, i.e., a prevalence of 78.3% (95% CI: 67.9-88.7%). The prevalence of T. gondii infection in muscles and organs analyzed by specific PCR targeting B1 gene (43.3%; 95% CI: 37-49.6%) was significantly higher than those analyzed for ITS-1 gene detection (15%; 95%CI: 10.4-19.5%) (p < 0.001). Heart samples had the highest T. gondii infection prevalence, as well as targeting either B1 gene (48.3%; 95% CI: 35.6-60.9%) or ITS-1 gene (21.6%; 95% CI: 11.2-32%). The present study showed that the consumption of undercooked free-range chicken meat represents a high risk for seronegative pregnant women. Our phylogenetic analysis revealed homology with wild and domestic birds and domestic mammals and a large geographic distribution.

Prevalence of Toxoplasma gondii in retail fresh meat products from free-range chickens in Spain

Introduction

Toxoplasma gondii is one of the most prevalent zoonotic protozoan parasites worldwide and affects the vast majority of warm-blooded animal species, including humans. Postnatal infection in humans occurs through the ingestion of sporulated T. gondii oocysts or via the oral intake of parasite tissue cysts during the consumption of raw or undercooked meat. In this regard, given their high exposure to oocysts, chickens (Gallus domesticus) raised on the ground constitute a potential source of T. gondii.

Material and Methods

For the first time in Spain, a survey was undertaken in commercial retail free-range poultry. A total of 50 thighs from different animals were analysed. The samples were homogenised and an acid pepsin digestion procedure was applied prior to molecular analysis. Toxoplasma gondii DNA was isolated from meat by qPCR. Two sets of primers were used for DNA amplification targeting the specific sequence of a 529 bp repeat element and another set of primers was utilised for the surface antigen protein-1 gene.

Results

DNA extracted from 5 out of 50 tissue samples was positive for both genes by qPCR amplification.

Conclusion

The 10% prevalence of Toxoplasma infection found in commercial free-range chickens raises public health issues.

Global seroprevalence of Toxoplasma gondii in Camelidae: A systematic review and meta-analysis

PURPOSE

The present study aimed to analyze data available of the seroprevalence of Toxoplasma gondii (T. gondii) among camelids around the world.

METHODS

The search was performed using seven international databases including Scopus, PubMed, Google Scholar, ProQuest, ScienceDirect, Web of Science, and EMBASE up to 11 October 2018. Random effects model was used to determine the pooled seroprevalence of T. gondii infection with 95% confidence intervals (CI) and analyzed data from four continents. Subgroup and meta-regression analyses were also performed according to continent and gender.

RESULTS

In total, 42 studies out of 3517 published articles involving 14,542 camels from 17 countries were included for the final analyses. The global pooled seroprevalence of T. gondii infection in the Camelidae family was 28.16% (95% CI 23.64-32.68%). Besides, the highest seroprevalence rate was in Europe (49.64%) followed by Africa (37.63%), America (21.76%), and Asia (17.58%). Moreover, the overall seroprevalence rates of T. gondii infection were 22% (95% CI 10-33%) and 15% (95% CI 9-22%) for the females and males, respectively.

CONCLUSION

This meta-analysis showed a high seroprevalence of T. gondii infection in camelids as these animals play an important role in the transmission cycle of this zoonotic disease.

Comparison of serological and molecular techniques to detect Toxoplasma gondii in free-range chickens (Gallus gallus domesticus)

The present study aimed to compare different indirect and direct diagnostic techniques to diagnose Toxoplasma gondii in free-range chickens. Samples of 386 chickens obtained from 24 Paraná properties were used for serological analysis by indirect fluorescent antibody test (IFAT), modified agglutination test (MAT), and enzyme-linked immunosorbent assay (ELISA). Animals positive by IFAT and/or MAT had their tissues submitted to the mouse bioassay, and those who were positive in this technique had their blood, tissues, and acidic pepsin tissue digestion submitted to PCR (conventional, nested, and quantitative-PCR (qPCR)). One hundred and nineteen chickens (30.8 %) were positive in at least one of the serological tests, being 102 (26.4 %) in the IFAT, 64 (16.6 %) in the MAT, and 62 (16.0 %) in the ELISA. The IFAT was used as a gold standard, and the MAT showed higher sensitivity (46.0 %) and specificity (94.0) compared to ELISA (43.5 % and 93.6 %, respectively). Ninety samples of eighteen chickens positive in the mouse bioassay were subjected to PCR, and according to molecular tests, the conventional PCR detected the T. gondii DNA in 30 % (27/90) of the samples, in 38.8 % (35/90) with nested-PCR and 40.0 % (36/90) with real-time. According to molecular analyzes, the sensitivity was higher in ITS1 nested-PCR (69.4 %) and specificity in conventional PCR-529bp (90.7 %), using the qPCR as the gold standard. MAT and ELISA had similarities in concordance analyzes. The IFAT was the serological technique with the highest agreement with the mouse bioassay, and serological tests in parallel showed to be a good screening option for the isolation of T. gondii in chick tissues. The PCR markers effectively detected the parasite DNA, and the heart was the tissue with the highest number of positives samples. The conventional PCR had sensitivity similar to nested-PCR and qPCR and could be a cheaper alternative to diagnose T. gondii infection in chicken tissues.

Experimental infection with Toxoplasma gondii in broiler chickens (Gallus domesticus): seroconversion, tissue cyst distribution, and prophylaxis

Toxoplasma gondii is a widespread zoonotic protozoan that infects most species of mammals and birds, including poultry. This study aimed to investigate the course of T. gondii infection and the efficacy of diclazuril and Artemisia annua in preventing infection in experimentally infected chickens. Seventy-five 1-month-old chickens, female and male, were randomly divided into five groups (n = 15 each) as follows: (1) uninfected untreated (negative control, NC); (2) infected with T. gondii genotype II/III isolated from a wild cat (group WC); (3) infected with T. gondii genotype II isolated from a domestic cat (group DC); (4) infected with T. gondii domestic cat strain and treated with the anticoccidial diclazuril (group DC-D); and (5) infected with T. gondii domestic cat strain and treated with the medicinal plant Artemisia annua (group DC-A). Clinical signs, body temperature, mortality rate, weight gain, feed conversion ratio, hematological parameters, and the presence of T. gondii-specific IgY antibodies were recorded in all groups. Five chickens per group were euthanized 28 days post-infection (p.i.) and their brains, hearts, and breast muscle tested for T. gondii by mouse bioassay and polymerase chain reaction (PCR). No clinical signs related to the experimental infection were observed throughout the study period. T. gondii-specific antibodies were detected by day 28 p.i., but not in all infected chickens. Overall, T. gondii DNA was detected (bioassay or tissue digests) in all infected and untreated chickens (10/10), while viable parasite (bioassay) was isolated from 7 out of 10 chickens. The parasite was most frequently identified in the brain (7/10). There were no differences in the T. gondii strains regarding clinical infection and the rate of T. gondii detection in tissues. However, higher antibody titers were obtained in chickens infected with T. gondii WC strain (1:192) comparing with T. gondii DC strain (1:48). A. annua reduced replication of the parasite in 3 out of 5 chickens, while diclazuril did not. In conclusion, broiler chickens were resistant to clinical toxoplasmosis, irrespective of the strain (domestic or wild cat strain). The herb A. annua presented prophylactic efficacy by reduced parasite replication. However, further studies are required aiming at the efficacy of diclazuril and A. annua for the prevention of T. gondii infection in chickens using quantitative analysis methods.

Seroprevalence, Risk Factors, and Genotypes of Toxoplasma gondii in Free-Range Chickens Intended for Human Consumption in China

Toxoplasma gondii is a protozoan with worldwide distribution that infects birds and mammals, including humans. The consumption of free-range chicken meat is a common practice in many parts of the world. However, little information is available concerning the molecular prevalence and genotypes of T. gondii infection in free-range chickens intended for human consumption in China. In this study, a total of 1360 serum samples were collected from food markets in Hunan province of China for detecting T. gondii antibodies by indirect hemagglutination assay. In addition, 650 brain tissues were also collected to investigate T. gondii DNA by amplification of B1 gene with a seminested polymerase chain reaction (PCR), and the positive DNA samples were typed at 10 genetic markers using multilocus PCR-restriction fragment length polymorphism. Antibodies to T. gondii were detected in 457 of the examined serum samples (33.6%; 95% confidence interval [CI]: 31.1-36.1), and 72 DNA samples (11.1%; 95% CI: 8.6-13.4) were positive for the T. gondii B1 gene. In this study, region and age of free-range chickens were shown to be risk factors for T. gondii infection (p < 0.01). Two genotypes (ToxoDB#9 and ToxoDB#52) were identified from two samples with complete genotyping results. Our study revealed a high prevalence of T. gondii infection in free-range chickens intended for human consumption in Hunan province, suggesting that recommendations to consumers should be made, especially in some regions of China where consumption of undercooked chicken meat is common. This is the first genetic characterization of T. gondii in free-range chickens intended for human consumption in Hunan province, China, and also the first report of genotype ToxoDB#52 in China.

Epidemiologic significance of Toxoplasma gondii infections in chickens (Gallus domesticus): the past decade

Toxoplasma gondii infections are common in humans and animals worldwide. Domestic free-range chickens (Gallus domesticus) are excellent sentinels of environmental contamination with T. gondii oocysts because they feed on the ground. Chickens can be easily infected with T. gondii; however, clinical toxoplasmosis is rare in these hosts. Chickens are comparatively inexpensive and thus are good sentinel animals for T. gondii infections on the farms. Here, the authors reviewed prevalence, the persistence of infection, clinical disease, epidemiology and genetic diversity of T. gondii strains isolated from chickens worldwide for the past decade. Data on phenotypic and molecular characteristics of 794 viable T. gondii strains from chickens are discussed, including new data on T. gondii isolates from chickens in Brazil. This paper will be of interest to biologists, epidemiologists, veterinarians and parasitologists.

A novel luciferase-linked antibody capture assay (LACA) for the diagnosis of Toxoplasma gondii infection in chickens

Toxoplasma gondii is an obligate intracellular protozoan parasite that causes the most common parasitic zoonosis worldwide in multiples species of mammals and birds. Although free-range chickens may play a role as an important reservoir for T. gondii, there is no reliable and commercially available diagnostic test for this disease in chickens. In this study, we aimed to develop a novel Luciferase-linked Antibody Capture Assay (LACA) for the serodiagnosis of Toxoplasma infection in chickens. Recombinant nanoluciferase fused-T. gondii dense granule antigen 8 (rNluc-GRA8) was produced and applied to LACA assay as a diagnostic antigen. GRA8-LACA was tested with the sera from uninfected and experimentally infected chickens with T. gondii and other parasitic pathogens and showed unexpectedly high sensitivity (90.5%) and specificity (95.4%). Interestingly, E. coli lysate expressing rNluc-GRA8 could be applied in GRA8-LACA with 85.7% sensitivity and an increased specificity (96.9%) that gave better diagnostic performance compared to conventional ELISA. We applied our diagnostic system to examine 267 free-range chicken sera collected from 12 farms and 100 closed-house broiler chicken sera from local poultry abattoirs. The overall seroprevalence of toxoplasmosis in free-range chickens was 10.9% (95% CI: 10.6%-11.1%), while no positive case was found in broiler chickens. GRA8-LACA could be a useful diagnostic technique for T. gondii infection in chickens. The detection of T. gondii seropositive chickens in this study warns a potential risk of Toxoplasma transmission by the consumption of raw or undercooked chicken meat.

Native SAG1 in Toxoplasma gondii lysates is superior to recombinant SAG1 for serodiagnosis of T. gondii infections in chickens

Toxoplasma gondii can infect almost all mammals and birds, including chickens. The aim of this study was to identify an appropriate immunogenic antigen for serodiagnosis of T. gondii infections in chickens. We examined serum samples from chickens that were intravenously or intraperitoneally infected with 10⁶-10⁸ tachyzoites of T. gondii strains PLK, RH, CTG, ME49 or TgCatJpGi1/TaJ using enzyme-linked immunosorbent assays (ELISAs), latex agglutination tests (LATs) and western blotting. Regardless of parasite strain or infection dose and route, the commercial LAT was positive for almost all sera collected 1 week post-infection. However, at 2 weeks post-infection, LATs were negative in the same birds. ELISAs using the Escherichia coli-produced recombinant T. gondii antigens SAG1 and GRA7 showed strong signals at 1-2 weeks post infection, but thereafter diminished for the majority of serum samples. In contrast, western blotting against crude tachyzoite antigens showed a persistent band up to 4 weeks post-infection. Sera from these chickens reacted much more strongly with SAG1 from crude tachyzoite antigens than with recombinant SAG1. Even in experimentally-infected birds whose parasite burdens in tissue were undetectable, sera still reacted with native SAG1. We tested sera from free-range chickens on a small farm in Ghana, Africa, using western blotting and found that the serum of one bird reacted with a single band of approximately 27 kDa, the putative molecular weight of SAG1. Thus we conclude that native SAG1, but not E. coli-produced recombinant SAG1, is suitable for serodiagnosis of T. gondii infections in chickens.

Experimental Toxoplasma gondii and Eimeria tenella co-infection in chickens

The widespread apicomplexan parasites Toxoplasma gondii (T. gondii) and Eimeria tenella (E. tenella) are important pathogens with high prevalence in poultry. The aim of our study was the investigation of mutual influences in co-infected chickens, focusing on immune response and course of infection. Two separate trials were performed using in total 96 1-day-old chickens, divided into four study groups: group NC (negative control, uninfected), group PC-T (oral or intramuscular infection with T. gondii oocysts (trial 1) or tachyzoites (trial 2), respectively), group PC-E (oral infection with E. tenella (trial 1) or E. tenella and Eimeria acervulina (trial 2)), and group TE (co-infection). T. gondii and Eimeria infections were validated by different parameters, and cytokine expression in the gut and spleen was investigated. T. gondii-specific antibodies were detected earliest 4 days post infection (p.i.) by immunoblot and direct DNA detection was possible in 22.1% of all tissue samples from infected chickens. Eimeria spp. merogony seemed to be enhanced by co-infection with T. gondii, interestingly without marked differences in oocyst excretion between co-infected and Eimeria spp. mono-infected chickens. An increase of messenger RNA (mRNA) expression of Th1- (IFN-γ, IL-12, TNF-α) and Th2-related cytokines (IL-10) mainly in groups PC-E and TE was observed, however, without statistically significant differences between co-infection and single infection with Eimeria. In conclusion, most of the measurable immune response could be attributed to Eimeria infection. To the best of our knowledge, this is the first report on co-infection experiments of T. gondii with Eimeria spp. in chickens.

Gallus gallus domesticus are resistant to infection with Neospora caninum tachyzoites of the NC-1 strain

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Neospora caninum may have been eliminated by the hens.

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The infected animals from different groups exhibited no changes in weight gain and feed intake.

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The tachyzoite infection does not appear to be appropriate to induce chronic infections in hens.

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The infection susceptibility in birds “in ovo” appears to be distinct in adult animals.

The aim of this study was to experimentally evaluate infection in Gallus gallus domesticus with Neospora caninum tachyzoites of the NC-1 strain. Experimental infection was conducted in 90-day-old chickens, embryonated eggs and bioassays in dogs. In the first experiment, poults were randomly divided into four groups. Groups I and II were provided feed with coccidiostat, whereas groups III and IV received feed without coccidiostat. When the poults from groups I and III reached 90 days of age, they received a subcutaneous inoculation of N. caninum. Once the hens entered their egg-laying period, during the following 30 days, the eggs were collected, identified, weighed and placed in an incubator. On the 70th day after inoculation, all animals, including the chicks, were euthanized. Tissue samples from the adult poultry and chicks were collected for histopathology, immunohistochemistry (IHC) and PCR. Brain tissue and pectoral muscle samples from infected birds were fed to two dogs. Notably, the average weight of the group III eggs was lower than that of the group IV eggs (p < 0.05). No changes consistent with infection in adult poultry or chicks were detected by histopathology or IHC; moreover, no amplified parasite DNA was detected in the birds’ tissues or dogs’ feces. No dog eliminated oocysts. In the second experiment, the embryonated chicken eggs were inoculated with 1 × 10²N. caninum tachyzoites, on the 10th day of incubation, and chicks born from these eggs were housed in boxes suitable for the species and received commercial feed and distilled water ad libitum. On the 30th day after infection (DAI), the poultry were euthanized, and their organs were processed as described in experiment I. The amplification of parasite DNA was observed in the spleen and pectoral muscles of one of the birds. The ingestion of bird tissues by dogs did not result in oocyst elimination. These results indicate that the parasite may have been eliminated by the host and that the use of tachyzoites to induce chronic disease might be a poor source for hens.

Occurrence of anti-Toxoplasma gondii antibodies and parasite DNA in backyard chicken breeding in Northeast, Brazil

Abstract The aim of the present study was to investigate the occurrence of anti-Toxoplasma gondii antibodies and parasite DNA in backyard chickens bred in the metropolitan area of Recife, Brazil. In total, 212 serum samples were collected from 16 properties, and 12 backyard chickens were collected in the six sanitary districts of Recife. An indirect immunofluorescence assay (IFA) was used to investigate the occurrence of anti-Toxoplasma gondii antibodies. Polymerase chain reaction (PCR) was used to detect T. gondii DNA in brain, heart, liver and lung specimens. Of the samples analyzed by serology, 86/212 (40.56%) were positive; of the samples analyzed by PCR, 2/12 (16.7%) were positive, with both samples positive by both tests (serological and molecular). The presence of antibody anti-T. gondii and parasite DNA in tissues of these animals are worrying aspects for public health because there is a risk of transmission of the parasite to humans through eating undercooked or raw meat. Based on the results, the adoption of preventive measures to prevent the cats access to the chickens creations should be encouraged, since these animals were identified in most of the studied properties.

Immunoproteomic technology offers an extraordinary diagnostic approach for Toxoplasma gondii infection

Immunoproteomic technology offers an exceptional tool to fill the blanks that still exist in diagnosis of Toxoplasma gondii infection despite its annotated sequence. The pitfalls of serological assays and current immunoproteomic approaches are accentuated, and new approaches are presented to improve the signal and to eliminate the noise produced by blocking-specific background. This review also highlights examples where immunoproteomic studies have contributed to broaden our understanding of toxoplasmosis diagnosis. Further promising solutions, which immunoproteomic technology can grant for toxoplasmosis diagnosis are part of an intense discussion.

Pathogenicity of Five Strains of Toxoplasma gondii from Different Animals to Chickens

Toxoplasma gondii is a protozoan parasite with a broad range of intermediate hosts. Chickens as important food-producing animals can also serve as intermediate hosts. To date, experimental studies on the pathogenicity of T. gondii in broiler chickens were rarely reported. The objective of the present study was to compare the pathogenicity of 5 different T. gondii strains (RH, CN, JS, CAT2, and CAT3) from various host species origin in 10-day-old chickens. Each group of chickens was infected intraperitoneally with 5×10⁸, 1×10⁸, 1×10⁷, and 1×10⁶ tachyzoites of the 5 strains, respectively. The negative control group was mockly inoculated with PBS alone. After infection, clinical symptoms and rectal temperatures of all the chickens were checked daily. Dead chickens during acute phage of the infection were checked for T. gondii tachyzoites by microscope, while living cases were checked for T. gondii infection at day 53 post-inoculation (PI) by PCR method. Histopathological sections were used to observe the pathological changes in the dead chickens and the living animals at day 53 PI. No significant differences were found in survival periods, histopathological findings, and clinical symptoms among the chickens infected with the RH, CN, CAT2, and CAT3 strains. Histopathological findings and clinical symptoms of the JS (chicken origin) group were similar to the others. However, average survival times of infected chickens of the JS group inoculated with 5×10⁸ and 1×10⁸ tachyzoites were 30.0 and 188.4 hr, respectively, significantly shorter than those of the other 4 mammalian isolates. Chickens exposed to 10⁸ of T. gondii tachyzoites and higher showed acute signs of toxoplasmosis, and the lesions were relatively more severe than those exposed to lower doses. The results indicated that the pathogenicity of JS strain was comparatively stronger to the chicken, and the pathogenicity was dose-dependent.

Exploring early and late Toxoplasma gondii strain RH infection by two-dimensional immunoblots of chicken immunoglobulin G and M profiles

Toxoplasma gondii is an intracellular apicomplexan parasite infecting warm-blooded vertebrate hosts, with only early infection stage being contained with drugs. But diagnosis differencing early and late infection was not available. In the present investigation, 2-dimensional immunobloting was used to explore early and late infections in chickens. The protein expression of T. gondii was determined by image analysis of the tachyzoites proteome separated by standard-one and conventional two-dimentional gel polyacrylamide electrophoresis (2D- PAGE). Pooled gels were prepared from tachyzoites of T. gondii. A representative gel spanning a pH range of 3-10 of the tachyzoite proteome consisted of 1306 distinct polypeptide spots. Two-dimensional electrophoresis (2-DE) combined with 2-DE immunoblotting was used to resolve and compare immunoglobulins (Igs) M & G patterns against Toxoplasma gondii strain RH (mouse virulent strain). Total tachyzoite proteins of T. gondii were separated by two-dimensional gel electrophoresis and analyzed by Western blotting for their reactivity with the 7 and 56 days post-infection (dpi) SPF chicken antisera. Different antigenic determinant patterns were detected during analysis with M and G immunoglobulins. Of the total number of polypeptide spots analyzed (1306 differentially expressed protein spots), 6.97% were identified as having shared antigenic polypeptide spots on immunoblot profiles with IgG and IgM antibodies regardless the time after infection. Furthermore, some of the immunoreactive polypeptide spots seemed to be related to the stage of infection. Interestingly, we found natural antibodies to toxoplasmic antigens, in addition to the highly conserved antigenic determinants that reacted with non-specific secondary antibody; goat anti-chicken IgG antibodies conjugated with horseradish peroxidase. In conclusion, unique reactive polypeptide spots are promising candidates for designation of molecular markers to discriminate early and late chicken infection.

Prevalence of antibody to Toxoplasma gondii in black-headed gulls (Chroicocephalus ridibundus), Dianchi Lake, China

Sera from 659 Black-headed Gulls (Chroicocephalus ridibundus) in Dianchi Lake, China were assayed for Toxoplasma gondii antibodies using the modified agglutination test (MAT). Specific T. gondii antibodies were detected in 131 (19.9%) Black-headed Gulls (MAT titer ≥ 1 ∶ 5). These results indicate that T. gondii infection is common in Black-headed Gulls.

Presence of dendritic cells in chicken spleen cell preparations and their functional interaction with the parasite Toxoplasma gondii

Toxoplasmosis is a worldwide epizootic disease of mammals. Chickens, albeit being less susceptible, can be contaminated in free-range flocks and may have an important role in parasite transmission. Plastic adherence selection of chicken spleen cells enriched 8F2+ (putative chicken CD11c) MHC II+ cells of the myeloid type; however, we did not succeed to separate dendritic cells from macrophages using their feature to become loosely adherent after culture as in mammals. Still we clearly identified dendritic-like cells being morphologically distinguishable from macrophages in the KUL01 (macrophage marker) negative fraction, exhibiting responsiveness to LPS and parasite extracts by developing characteristic cellular protrusions as well as a minor phagocytic incorporation of dead parasites. Live T. gondii tachyzoites were able to invade the two different types of myeloid adherent cells, to replicate, and to induce an overall decrease in the expression of MHC II and co-stimulatory molecules, CD80 and CD40. Our data indicate that dendritic cells in addition to macrophages may have a role in hiding viable replicating T. gondii tachyzoites from the immune system and in shuttling them to different organs in the chicken as previously described for different Apicomplexa infecting mammals.

Inactivation of exogenous endoparasite stages by chemical disinfectants: current state and perspectives

Chemical disinfection is common practice and inevitable to achieve sufficient control over parasites particularly in intensive animal housing systems. To identify suitable chemicals, reliable data on antiparasitic efficacy of disinfectants are required. This review summarizes recently published experience with procedures applied to evaluate the viability of a variety of endoparasites following physical or chemical stress. It is concluded that laboratory models used to assess antiparasitic efficacy of e.g. commercial disinfectants should consider the most resistant stages of both helminths and protozoa, i.e. ascarid eggs and coccidia oocysts. To ensure reproducibility and transparency, standardized protocols are pivotal. Such protocols are established on a national level (e.g. DVG guidelines in Germany); however, internationally accepted certification procedures are currently lacking.

First report of Toxoplasma gondii seroprevalence in peafowls in Yunnan Province, Southwestern China

Background

Toxoplasma gondii is an intracellular protozoan parasite infecting almost all warm-blooded animals, including birds, with a worldwide distribution. Surveys of T. gondii infection in wild birds have been reported extensively in the world, but little is known of T. gondii infection in peafowls worldwide. This study was performed to determine the seroprevalence of T. gondii infection in peafowls in Yunnan Province, southwestern China.

Methods

Sera from 277 peafowls, including 272 blue peafowls (Pavo cristatus) and 5 green peafowls (Pavo muticus) originated from two geographic areas in Yunnan Province were assayed for T. gondii antibodies using the modified agglutination test (MAT).

Results

Specific T. gondii antibodies were detected in 35 of 277 (12.64%) peafowls (MAT titer ≥ 1:5). Seropositive birds were found in both species, 33 in 272 blue peafowls and 2 in 5 green peafowls. There was no significant difference in T. gondii seroprevalence between the adolescent birds (6.74%) and the adult birds (6.67%) (P > 0.05). The geographical origins of peafowls was found to be highly associated with T. gondii infection in the present study, a statistically significant difference in T. gondii seropositivity was observed between peafowls from Kunming (31.08%) and those from Xishuangbanna Dai Autonomous Prefecture (5.91%) (OR = 10.956, 95% CI = 1.632-73.545, P = 0.014). Statistical analyses showed that there were no significant interactions between ages and geographical origins of peafowls (P > 0.05).

Conclusions

The results of the present survey indicated that infection of peafowls with T. gondii is widespread in Yunnan Province, which has significant public health concerns and implications for prevention and control of toxoplamosis in this province. To our knowledge, this is the first seroprevalence report of T. gondii infection in China’s southwestern Yunnan Province.

Seroprevalence of Toxoplasma gondii infection in household and stray cats in Lanzhou, northwest China

Background

Toxoplasma gondii is an important protozoan parasite infecting humans and almost all warm-blooded animals. As the only definitive host, cats play a crucial role in the transmission of T. gondii infection by shedding parasite oocysts in their feces. However, little information on T. gondii infection in cats was available in Lanzhou, northwest China. This study was performed to determine the seroprevalence of T. gondii infection in household and stray cats in Lanzhou, northwest China.

Results

A total of 221 (179 households and 42 strays) blood samples were collected from clinically healthy cats admitted to several pet hospitals located in Lanzhou City, between November 2010 and July 2011 for the serological detection of T. gondii infection. The majority (207) of these cats represented Chinese Lihua cats. 47 of 221 (21.3%) examined cats were seropositive for T. gondii infection using the modified agglutination test (MAT) at the cut-off of 1:25. The seroprevalence in household and stray cats was assessed to be 15.6% and 45.2%, respectively, and the difference was statistically significant (P <0.05). The seroprevalence ranged from 15.1% to 25.8% among different age groups, but the differences were not statistically significant (P >0.05). Studies showed that there was no relationship between seroprevalence and the gender (P >0.05).

Conclusions

The present survey indicated the high seroprevalence of T. gondii in cats in Lanzhou, northwest China, which poses a threat to animal and human health. Therefore, measures should be taken to control and prevent toxoplasmosis of cats in this area.

Molecular diagnosis of infections and resistance in veterinary and human parasites

Since 1977, >2000 research papers described attempts to detect, identify and/or quantify parasites, or disease organisms carried by ecto-parasites, using DNA-based tests and 148 reviews of the topic were published. Despite this, only a few DNA-based tests for parasitic diseases are routinely available, and most of these are optional tests used occasionally in disease diagnosis. Malaria, trypanosomiasis, toxoplasmosis, leishmaniasis and cryptosporidiosis diagnosis may be assisted by DNA-based testing in some countries, but there are very few cases where the detection of veterinary parasites is assisted by DNA-based tests. The diagnoses of some bacterial (e.g. lyme disease) and viral diseases (e.g. tick borne encephalitis) which are transmitted by ecto-parasites more commonly use DNA-based tests, and research developing tests for these species makes up almost 20% of the literature. Other important uses of DNA-based tests are for epidemiological and risk assessment, quality control for food and water, forensic diagnosis and in parasite biology research. Some DNA-based tests for water-borne parasites, including Cryptosporidium and Giardia, are used in routine checks of water treatment, but forensic and food-testing applications have not been adopted in routine practice. Biological research, including epidemiological research, makes the widest use of DNA-based diagnostics, delivering enhanced understanding of parasites and guidelines for managing parasitic diseases. Despite the limited uptake of DNA-based tests to date, there is little doubt that they offer great potential to not only detect, identify and quantify parasites, but also to provide further information important for the implementation of parasite control strategies. For example, variant sequences within species of parasites and other organisms can be differentiated by tests in a manner similar to genetic testing in medicine or livestock breeding. If an association between DNA sequence and phenotype has been demonstrated, then qualities such as drug resistance, strain divergence, virulence, and origin of isolates could be inferred by DNA-based tests. No such tests are in clinical or commercial use in parasitology and few tests are available for other organisms. Why have DNA-based tests not had a bigger impact in veterinary and human medicine? To explore this question, technological, biological, economic and sociological factors must be considered. Additionally, a realistic expectation of research progress is needed. DNA-based tests could enhance parasite management in many ways, but patience, persistence and dedication will be needed to achieve this goal.

Seroprevalence of Toxoplasma gondii infection in pet dogs in Lanzhou, Northwest China

BACKGROUND

In recent years, surveys of Toxoplasma gondii infection in dogs have been reported worldwide, including China. However, little is known about the prevalence of T. gondii in pet dogs in Northwest China. In the present study, the prevalence of T. gondii in pet dogs in Lanzhou, China was investigated using the modified agglutination test (MAT).

RESULTS

In this survey, antibodies to T. gondii were found in 28 of 259 (10.81%) pet dogs, with MAT titers of 1:20 in 14 dogs, 1:40 in nine, 1:80 in four, and 1:160 or higher in one dog. The prevalence ranged from 6.67% to 16.67% among dogs of different ages, with low rates in young pet dogs, and high rates in older pet dogs. The seroprevalence in dogs >3 years old was higher than that in dogs ≤1 years old, but the difference was not statistically significant (P >0.05). The seroprevalence in male dogs was 12.50% (17 of 136), and in female dogs it was 8.94% (11 of 123), but the difference was not statistically significant (P >0.05).

CONCLUSIONS

A high prevalence of T. gondii infection was found in pet dogs in Lanzhou, Northwest China, which has implications for public health in this region. In order to reduce the risk of exposure to T. gondii, further measures and essential control strategies should be carried out rationally in this region.