Modified Agglutination Test Research Articles

Seroepidemiology of Toxoplasma gondii in wild ruminants in Spain.

Toxoplasmosis is a parasitic zoonosis caused by Toxoplasma gondii which infects warm-blooded species worldwide. Humans can be infected through ingestion of tissue cysts from raw or undercooked meat, including game meat. A nationwide large-scale cross-sectional study was conducted to assess exposure to T.gondii in seven wild ruminant species in Spain. A total of 2,040 serum samples from 77 sampling sites randomly distributed in the five bioregions (BRs) covering mainland Spain were tested for antibodies against T.gondii using the modified agglutination test. The overall seroprevalence was 22.0% (449/2,040). Seroprevalence by species in decreasing order was as follows: 39.6% (141/356) in roe deer (Capreolus capreolus), 37.1% (138/372) in fallow deer (Dama dama), 16.6% (92/553) in red deer (Cervus elaphus), 14.0% (26/186) in Southern chamois (Rupicapra pyrenaica), 11.5% (24/209) in mouflon (Ovis aries musimon), 7.8% (27/346) in Iberian wild goat (Capra pyrenaica) and 5.6% (1/18) in Barbary sheep (Ammotragus lervia). Seropositivity was detected in 74.0% (57/77) of the sampling sites. Results indicate widespread but not homogeneous exposure to T.gondii in wild ruminant populations in Spain during the last two decades and highlight differences related to animal species and spatial distribution of these species in this country; this implies potential consequences of T.gondii for animal health, conservation and public health.

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.

Seroprevalence of Toxoplasma gondii in Wild Rats (Rattus rattus) in Northern Iran.

Rodents are considered as reservoir hosts for various pathogens (such as Toxoplasma gondii) and have been revealed to play an important role in the spread of several infectious diseases to humans and other animals. The aim of this investigation was to survey the prevalence of anti-T. gondii IgG antibodies in wild rats in Northern Iran. One hundred rats were caught using rat traps set in different areas in Northern Iran (September 2017). The thoracic cavity of each rat was opened, and then the blood sample was collected from the heart. IgG anti-Toxoplasma gondii antibodies were detected using the modified agglutination test (MAT) with a cutoff value equal to 1 : 40. Overall, 56% of rats were infected by T. gondii. Considering the sex of rats, 45% of male and 55% of female rats were seropositive, but the differences were not statistically significant. There was a significant difference between seropositivity and habitat types and age of rodents. Our findings have public health implications and confirm the high seroprevalence of T. gondii infection in northern Iran. The study established that wild rats represent an important and persistent wildlife intermediate host reservoir for T. gondii.

Toxoplasma gondii prevalence in carnivorous wild birds in the eastern United States.

Toxoplasma gondii is an important zoonotic protozoan parasite that can infect all warm-blooded animals including mammals and birds. Raptors can be intermediate hosts for T. gondii and the infection may be dependent on their feeding habits. In this study, we investigated the seroprevalence of T. gondii in ten raptor species from Florida, Pennsylvania, and Tennessee followed by a parasite bioassay on select seropositive samples. From a total of 155 raptors, we detected T. gondii antibodies using a modified agglutination test (cutoff 1:25) in 32 (20.6%) birds. The T. gondii seroprevalence was 44.8% in Falconiformes (13/29), 75% in Strigiformes (15/20), and 3.8% in Ciconiiformes (4/106). All Ciconiiformes samples (hearts and sera) were collected from Pennsylvania during nuisance wildlife removal projects and all birds were apparently healthy. Falconiform and Strigiform samples were collected from an exotics clinic in Tennessee and a rehabilitation center in Florida. All sampled birds were dead or euthanatized due to failure of rehabilitation or treatment. There was no statistically significant difference in T. gondii seroprevalence between Tennessee and Florida in the tested raptors. There was also no statistically significant difference in T. gondii exposure between males and females or adults and subadults. Mice bioassay attempts using fresh brain and/or heart tissue were performed on four seropositive birds. We isolated viable T. gondii tachyzoites from one red-shouldered hawk (Buteo lineatus) and genotyped the isolate using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) of ten genetic markers. The isolated strain was designated as TgHawkFL1, which is ToxoDB PCR-RFLP genotype #28. Further research is needed to investigate the prevalence of T. gondii in raptors in the United States to obtain a better understanding of the life cycle, wildlife population impacts, and transmission dynamics of the parasite.

Isolation, genotyping and virulence determination of a Toxoplasma gondii strain from non-human primate from China.

Toxoplasma gondii infects almost all warm-blooded animals, including humans and non-human primates. Many cases of T. gondii infection in non-human primates have been reported worldwide. In this study, 15 monkeys were collected from zoos in Henan Province between 2016 and 2019. A modified agglutination test (MAT) (cut-off: 1:8) showed that 46.7% (7/15) of the heart juices had T. gondii IgG antibody transformation. One viable T. gondii strain was successfully isolated from the myocardium of a rhesus monkey by bioassay in mice. This strain was designated as TgMonkeyCHn1. The DNA of T. gondii tachyzoites was obtained using cell cultures, and the genotype of this strain was determined by PCR-RFLP with 10 markers and the virulence genes ROP5 and ROP18. The genotype and ROP18/ROP5 (3/6) of TgMonkeyCHn1 did not match any known genotypes. In addition, the TgMonkeyCHn1 formed low number of tissue cysts and was non-lethal to mice. To our knowledge, this is the first T. gondii strain isolated from Old World monkeys. Rhesus monkey is a new host record for T. gondii.

Seroprevalence of Toxoplasma gondii in outdoor dogs and cats in Bangkok, Thailand.

The aim of this study was to estimate the seroprevalence and risk factors associated with Toxoplasma gondii exposure in dogs and cats from Bangkok, Thailand. Blood samples from 318 dogs and 321 cats were tested for T. gondii antibodies by modified agglutination test (cut-off 1:25). Additionally, 18 dogs and 20 cats were longitudinally sampled for T. gondii antibodies during the same study period, between June and July 2019. The overall seroprevalence in dogs and cats was 7.9% (25/318; 95% CI 4.9–10.8%) and 18.7% (95% CI 14.4–23.0%), respectively. For dogs, risk factors identified were being a mixed-breed animal and living totally outdoors, while increasing age was shown to be a risk factor for cats. Seroconversion was not detected and titres from positive animals remained constant over longitudinal study. The present study indicates that there is a prominent presence of T. gondii in urban and peri-urban areas of Bangkok, suggesting that outdoor dogs and cats should be considered as a possible risk factor for humans.

Seroprevalence and risk factors ofToxoplasma gondiiinfection in wild ungulates that cohabit in a natural park with human–animal interaction in the Mediterranean ecosystem

The possibility of Toxoplasma gondii transmitted from game meat to humans is of public health concern. Here we determined seroprevalence and risk factors associated with T.gondii in large game ungulates that cohabit in Sierras de Cazorla, Segura and Las Villas Natural Park (SCSV-NP) (Southern Spain), a natural park with high human-animal interaction. Antibodies against T.gondii in 328 wild ungulates were assayed by the modified agglutination test (MAT≥1:25). Antibodies were found in 39 (11.9%, 95% CI: 8.4-15.4) wild ungulates, with seroprevalence levels of 20.8% in wild boars (Sus scrofa) (5/24), 19.0% in fallow deer (Dama dama) (12/63), 13.9% in Iberian ibex (Capra pyrenaica hispanica) (14/101), 7.9% in red deer (Cervus elaphus) (6/76), and 3.1% in mouflons (Ovis aries musimon) (2/64). Significantly higher seroprevalence was observed in fallow deer and wild boars compared to mouflons. Animals living close to urban areas (<2km) had 4.6-times higher risk compared to those living at >5km of urban areas. The results indicate high circulation of T.gondii in wild ungulates in SCSV-NP, which is of animal and public health concern. The increased seroprevalence of T.gondii detected in wildlife ungulates living close to urban areas may increase human infection in those areas if meat from infected animals is consumed raw or undercooked.

A hotspot of Toxoplasma gondii Africa 1 lineage in Benin: How new genotypes from West Africa contribute to understand the parasite genetic diversity worldwide.

Through international trades, Europe, Africa and South America share a long history of exchanges, potentially of pathogens. We used the worldwide parasite Toxoplasma gondii to test the hypothesis of a historical influence on pathogen genetic diversity in Benin, a West African country with a longstanding sea trade history. In Africa, T. gondii spatial structure is still non-uniformly studied and very few articles have reported strain genetic diversity in fauna and clinical forms of human toxoplasmosis so far, even in African diaspora. Sera from 758 domestic animals (mainly poultry) in two coastal areas (Cotonou and Ouidah) and two inland areas (Parakou and Natitingou) were tested for T. gondii antibodies using a Modified Agglutination Test (MAT). The hearts and brains of 69 seropositive animals were collected for parasite isolation in a mouse bioassay. Forty-five strains were obtained and 39 genotypes could be described via 15-microsatellite genotyping, with a predominance of the autochthonous African lineage Africa 1 (36/39). The remaining genotypes were Africa 4 variant TUB2 (1/39) and two identical isolates (clone) of Type III (2/39). No difference in terms of genotype distribution between inland and coastal sampling sites was found. In particular, contrarily to what has been described in Senegal, no type II (mostly present in Europe) was isolated in poultry from coastal cities. This result seems to refute a possible role of European maritime trade in Benin despite it was one of the most important hubs during the slave trade period. However, the presence of the Africa 1 genotype in Brazil, predominant in Benin, and genetic analyses suggest that the triangular trade was a route for the intercontinental dissemination of genetic strains from Africa to South America. This supports the possibility of contamination in humans and animals with potentially imported virulent strains.

Toxoplasma gondii among captive wild mammals in zoos in Brazil and Cuba: seroprevalence and associated risk factors.

Toxoplasma gondii is a zoonotic parasite of worldwide distribution that can infect several species of homeothermic animals. Few studies have evaluated the exposure of captive wild animals to T. gondii. This study involved a serological survey of anti-T. gondii antibodies in mammals kept in Cuba's National Zoo (PZN) and in the Rio de Janeiro Zoo (RIOZOO) in Brazil. The study consisted of a total of 231 serum samples from mammals, 108 from PZN and 123 from RIOZOO. All the samples were subjected to IgG anti-T. gondii testing by means of the inhibition ELISA method and the modified agglutination test, respectively. T. gondii antibodies were detected in 85.2% samples from PZN and 32.5% samples from RIOZOO. At the PZN, Perissodactyla (92.3%) was the order with the highest serological prevalence rate, whereas at the RIOZOO, the order Primates (46.7%) stood out (p<0.05). In addition to this association, the origin of the PZN animals was also associated with T. gondii infection. This finding demonstrates the need for constant veterinary monitoring of captive wild mammals in order to link the serological diagnosis with clinical alterations indicative of toxoplasmosis.

Lower seroprevalence of Toxoplasma gondii in swine from central China after an outbreak of African swine fever.

Toxoplasma gondii is widespread worldwide and can infect swine. This study evaluated the seroprevalence of T. gondii in swine from central China after an outbreak of African swine fever (ASF). A total of 2683 swine serum samples were collected from farms in four provinces. Of the serum samples, 1.42% (38/2683) (95% CI, 1.03–1.94) tested positive for T. gondii IgG antibody by a modified agglutination test (MAT) (cut-off: 1:25). Comparing with the results of previous studies, specifically our survey from before the outbreak, the seroprevalence of T. gondii in swine from central China was significantly decreased after the occurrence of ASF (OR = 7.679, 2015–2017 vs. 2019–2020). In general, the proportion of seropositive animals increased with the age of the swine, indicating post-natal transmission of T. gondii. Furthermore, there was a significant difference in seroprevalence between suckling pigs and weaned pigs (p < 0.05). This is the first large-scale investigation of T. gondii infection in swine after an ASF outbreak in China. The lower seroprevalence of T. gondii in swine after ASF may be due to stricter biosecurity measures on the farms, but results indicated swine exposure to zoonotic parasites despite these measures. This highlights that pigs must be considered a potential source of human T. gondii infections.

Toxoplasma gondii Strain and Dose Effects on Feed Conversion Rate, Body Weight, Serum Antibodies Response, and Systemic Distribution in Intraperitoneally Infected Domestic Turkey Poults.

Toxoplasmosis, caused by the protozoan parasite Toxoplasma gondii, is an important foodborne zoonosis affecting a wide range of hosts, including birds. This study investigated the seroconversion, feed conversion rate, weight gain, and parasite tissue tropism as a function of parasite dose and virulence in turkeys. Twenty-five 4-wk-old female domestic turkeys (Meleagris gallapavo) were intraperitoneally infected with two different strains and two doses (105 and 108 tachyzoites/ml) of T. gondii tachyzoites, resulting in four treatment groups. A fifth group of 10 additional birds was intraperitoneally injected with sterile phosphate-buffered saline as a negative control. All birds remained subclinical except for three birds in the two high-dose groups (108 tachyzoites/ml). Survival rate was 88% (22/25). A 92% seroconversion rate was detected in T. gondii-infected birds using a modified agglutination test. Antibody titers as well as weight gain were related to the dose and strain of T. gondii used. Feed conversion rate was higher in the high-dose groups compared with low-dose and control groups, while weight gain was significantly lower at 14 days postinfection in the group infected with 108 tachyzoites/ml of virulent T. gondii strain. Gross lesions were detected in the pancreas and lungs of only one bird, and histopathologic findings varied depending on strain and dose. The organs that most frequently contained T. gondii DNA as detected by quantitative PCR were the brain and the heart, followed by the bursa of Fabricius and the lungs. This study confirmed that turkeys can be infected with T. gondii, and turkeys can show signs of infection when exposed to high doses. Given the increased practice of outdoor-raised livestock and wildlife consumption, continual experimental infection of T. gondii in wild and domestic animals should be pursued.

Isolation and characterization of Toxoplasma gondii from captive caracals (Caracal caracal).

Toxoplasma gondii infects most warm-blooded animals, including humans. Felids can serve as both intermediate and definitive hosts for T. gondii. However, there is no direct evidence to prove the caracal (Caracal caracal) is an intermediate host for T. gondii. Here, we report T. gondii infection in two caracals in a zoo from China. Antibodies against T. gondii were found in both caracals by modified agglutination test (MAT) (cut-off titer: 1:25). Tissue cysts were observed in the leg and tongue muscles of caracal case# 1. These cysts were confirmed as T. gondii by immunohistochemical staining and T. gondii was detected by polymerase chain reaction (PCR). Viable T. gondii strain was isolated from the striated muscles of caracal case# 2 and designated as TgCaracalCHn1. DNA from tachyzoites obtained from cell cultures was characterized by RFLP-PCR using ten markers (SAG1, SAG3, SAG2, BTUB, c22-8, GRA6, c29-2, PK1, L358, and Apico) and the virulence genes (ROP5 and ROP18). The results indicate that this isolate belongs to ToxoDB genotye #2 (Type III). The virulence of this isolate was evaluated in BALB/c mice. A dose of 104 TgCaracalCHn1 tachyzoites was non-lethal to mice. Tissue cysts were found in brain tissues of infected mice. This result confirmed that the TgCaracalCHn1 is non-virulent to mice. Current study documents first isolation of viable T. gondii strain from caracal and also indicates that caracal can act as new intermediate host for T. gondii.

Environmental factors associated With Toxoplasma gondii Exposure in Neotropical Primates of Costa Rica.

The apicomplexan parasite Toxoplasma gondii (T. gondii) has been found in more than 350 species of homoeothermic vertebrates in diverse climates and geographic areas. In most animals, T. gondii produces mild or asymptomatic infection. However, acute and hyperacute toxoplasmosis is associated with high mortality rates observed in Neotropical primates (NP) in captivity. These primates are distributed in 20 countries across the Americas, and although infection has been reported in certain countries and species, toxoplasmosis in the wild and its impact on NP population survival is unknown. Differences among species in exposure rates and disease susceptibility may be due in part to differences in host behavior and ecology. Four species of NP are found in Costa Rica, i.e., howler (Alouatta palliata), spider (Ateles geoffroyi), capuchin (Cebus imitator), and squirrel monkeys (Saimiri oerstedii). This study reports NP exposure to T. gondii using the modified agglutination test in 245 serum samples of NP (198 wild and 47 from captivity) from Costa Rica. Associations of serostatus with environmental (forest cover, annual mean temperature), anthropogenic (human population density), and biological (sex) variables in howler and capuchin monkeys were evaluated. The seroprevalence among wild NP was 11.6% (95% CI = 7.7–17.34), compared with 60% in captive monkeys (95% CI = 44.27–73.63), with significant differences between species (X2 = 20.072; df = 3, p = 0.000164), suggesting an effect of behavior and ecology. In general, antibody titers were low for wild NP (<1:128) and high for captive NP (>1:8192), suggesting higher exposure due to management factors and increased life span in captivity. Seropositivity in howler monkeys was positively related to forest cover and inversely related to annual rainfall. For capuchins, annual rainfall was inversely related to seropositivity. Surveillance of T. gondii exposure in NP in captivity and in the wild is required to understand drivers of the infection and develop novel strategies to protect them.

Toxoplasma gondii Infection in Cattle Egret (Bubulcus ibis): First Report from Shebin El-Kom, Menoufia Governorate, Egypt.

Toxoplasma gondii (T. gondii) is capable of infecting a broad range of intermediate hosts. Cattle egret (Bubulcus ibis) is a species of herons that is common in Egypt. This work aimed to study the prevalence of T. gondii in cattle egret which is an efficient tool of investigating environmental contamination with T. gondii. Serum, heart and brain tissues of 51 cattle egrets were collected from Shebin El-Kom, Menoufia, Egypt and tested using Modified Agglutination Test (MAT) and mice bioassay. There was a detection rate of 13.7% (7/51) in these birds using MAT. By intraperitoneal injection of mice with heart and brain tissues digest of MAT positive birds, the parasite was isolated from two T. gondii sero-positive birds (28.6%). The mice bioassay was confirmed by MAT, Hematoxylin and Eosin (HAND E) staining of the brain of the infected mice, also by Polymerase Chain Reaction (PCR) and sequencing. This is the first report of T. gondii infection in cattle egret from Egypt and more studies are needed on Egyptian wildlife to understand the sylvatic life cycle of the parasite.

Toxoplasma gondii seropositivity across urban and agricultural landscapes in an Australian owl

ABSTRACT In Australia, Toxoplasma gondii is an introduced parasite with a wide host range. House cats (Felis catus) are one of its definitive hosts. Little is known about T. gondii infection rates in Australian wildlife. Since cat abundance varies with landscape composition, we hypothesised that T. gondii infection would be more prevalent in urban and agricultural landscapes than intact bushland and sought to use samples from the Southern Boobook (Ninox boobook) as an indicator of ecosystem-wide T. gondii contamination. We used modified agglutination tests to determine T. gondii seropositivity in serum and meat juice samples taken from boobooks. Moderately low levels of seropositivity were detected and non-significant landscape-related patterns of seroprevalence were observed. We also examined correlations and interactions with owl age, season, injury status and exposure to an anticoagulant rodenticide. Only season showed significant correlations with observed seropositivity. To the best of our knowledge, this is the first published detection of T. gondii seropositivity in a wild predatory bird in Australia.

Epidemiological surveillance of Toxoplasma gondii in small ruminants in southern Spain

Toxoplasmosis, caused by the protozoan Toxoplasma gondii, is a worldwide zoonotic disease, which affects most warm-blooded species. Besides the zoonotic relevance, toxoplasmosis is one of the major causes of reproductive disorders in small ruminants. A cross-sectional study was carried out to determine the seroprevalence, spatial distribution and risk factors associated with T. gondii infection in sheep and goats in southern Spain. During 2015–2017, a total of 1,943 small ruminants (998 sheep and 945 goats) from 127 flocks were tested for antibodies against T. gondii using the modified agglutination test (MAT, cut-off 1:25). Antibodies against T. gondii were detected in 464 of the 998 sheep (46.5 %; CI95 %: 43.4–49.6%) and 362 of the 945 goats (38.3 %; CI95 %: 35.2–41.4%) tested. The farm prevalence was 98.4 % (CI95 %: 95.4–100%) for sheep and 93.7 % (CI95 %: 87.6–99.7%) for goats. The generalized estimating equation analysis showed that presence of cats and existence of previous reproductive disorders were risk factors potentially associated with T. gondii seropositivity in small ruminants. Two statistically significant spatial clusters (P < 0.001) were identified. The seroprevalence observed in the present study indicates a widespread exposure to T. gondii in sheep and goats in southern Spain, which might have important implications for animal and public health. Management measures should be implemented in small ruminant farms in this region in order to reduce the risk of T. gondii infections, particularly in those areas identified in the spatial analysis.

Relationship between Toxoplasma gondii seroprevalence and lamb marking in South Australian sheep flocks.

Toxoplasmosis in sheep has negative impacts on reproductive performance. This study aimed to estimate the prevalence in Toxoplasma gondii infection in the South Australian sheep population, and assess any association between within-flock prevalence and reproductive efficiency (measured by lamb marking percentage), climatic region and rainfall. A total of 875 individual mixed-age breeding ewes from 29 South Australian properties were blood sampled with an average of 30.2 ewes per property (min 28, max 32). Sera were tested for T. gondii-specific IgG antibody using a commercial Modified Agglutination Test kit. Overall, 209 of 875 (23.9%; 95% confidence interval [CI] 16.3% to 31.4%) of individual ewes tested seropositive for T. gondii-specific IgG antibodies, with a flock level seroprevalence of 28/29 (96.6%, 95% CI 96.6% to 100%). On individual farms, the seroprevalence ranged from 0% to 93.3%. Analysis showed that Kangaroo Island properties had significantly higher mean seroprevalence than any mainland climatic regions, and that the mainland regions did not significantly differ from each other. Linear regression revealed a significant association between seroprevalence and lamb marking percentage, with a slope of -5.4% lamb marking per +10% seroprevalence.

Distribution of Toxoplasma gondii Tissue Cysts in Shoulder Muscles of Naturally Infected Goats and Lambs

Toxoplasmosis has been recognized as a major public health problem worldwide. The consumption of uncooked or undercooked meat infected with Toxoplasma gondii tissue cysts is one of the main means of transmission of this parasite. Although sheep, goats, and pigs are commonly infected with T. gondii, little information is available on the distribution of T. gondii tissue cysts in naturally infected meat. In this study, we investigated the distribution of viable T. gondii tissue cysts in shoulder muscles of naturally infected lambs and goats. Hearts and shoulders of 46 lambs and 39 goats from a local grocery store were tested for T. gondii infection. Animals were evaluated for the presence of anti-T. gondii antibodies in heart blood and clots by the modified agglutination test. Fourteen of the 85 animals (seven lambs and seven goats) were seropositive. Six to 12 samples weighing 5, 10, and 50 g were obtained from shoulder muscles of each seropositive animal and used for bioassay in mice. The distribution of viable T. gondii differed according to the size of the sample analyzed, but in general larger sample sizes resulted in higher isolation rates (P < 0.05). Results of the study revealed an uneven distribution of T. gondii in muscle samples of lambs and goats and that T. gondii can be transmitted by consumption of very small servings (5 and 10 g) of meat when it is consumed raw or is undercooked.

Fluorescent bead-based serological detection of Toxoplasma gondii infection in chickens

BackgroundFree-ranging chickens are often infected with Toxoplasma gondii and seroconvert upon infection. This indicates environmental contamination with T. gondii.MethodsHere, we established a bead-based multiplex assay (BBMA) using the Luminex technology for the detection of T. gondii infections in chickens. Recombinant biotinylated T. gondii surface antigen 1 (TgSAG1bio) bound to streptavidin-conjugated magnetic Luminex beads served as antigen. Serum antibodies were detected by a fluorophore-coupled secondary antibody. Beads of differing color codes were conjugated with anti-chicken IgY or chicken serum albumin and served for each sample as an internal positive or negative control, respectively. The assay was validated with sera from experimentally and naturally infected chickens. The results were compared to those from reference methods, including other serological tests, PCRs and bioassay in mice.ResultsIn experimentally infected chickens, the vast majority (98.5%, n = 65/66) of birds tested seropositive in the BBMA. This included all chickens positive by magnetic-capture PCR (100%, n = 45/45). Most, but not all inoculated and TgSAG1bio-BBMA-positive chickens were also positive in two previously established TgSAG1-ELISAs (TgSAG1-ELISASL, n = 61/65; or TgSAG1-ELISASH, n = 60/65), or positive in an immunofluorescence assay (IFAT, n = 64/65) and in a modified agglutination test (MAT, n = 61/65). All non-inoculated control animals (n = 28/28, 100%) tested negative. In naturally exposed chickens, the TgSAG1bio-BBMA showed a high sensitivity (98.5%; 95% confidence interval, CI: 90.7–99.9%) and specificity (100%; 95% CI: 85.0–100%) relative to a reference standard established using ELISA, IFAT and MAT. Almost all naturally exposed chickens that were positive in bioassay or by PCR tested positive in the TgSAG1bio-BBMA (93.5%; 95% CI: 77.1–98.9%), while all bioassay- or PCR-negative chickens remained negative (100%; 95% CI: 85.0–100%).ConclusionsThe TgSAG1bio-BBMA represents a suitable method for the detection of T. gondii infections in chickens with high sensitivity and specificity, which is comparable or even superior to other tests. Since assays based on this methodology allow for the simultaneous analysis of a single biological sample with respect to multiple analytes, the described assay may represent a component in future multiplex assays for broad serological monitoring of poultry and other farm animals for various pathogens.

Serological evidence of Toxoplasma gondii and Chlamydia infection in alpacas (Vicugna pacos) in Shanxi Province, northern China

Toxoplasma gondii, Neospora caninum, Chlamydia and bluetongue virus (BTV) are four important pathogens which can cause reproductive loss. The present study was conducted to estimate the seroprevalence of T. gondii, N. caninum, Chlamydia and BTV in alpacas in Shanxi Province, northern China. A total of 251 serum samples were collected from alpacas, and antibodies against T. gondii and Chlamydia were examined by the modified agglutination test (MAT) and indirect hemagglutination assay (IHA), respectively. Antibodies to N. caninum and BTV were determined by using the commercially available competitive enzyme-linked immunosorbent assay (cELISA) kits, respectively. The overall seroprevalence of T. gondii was 9.16% (95% CI 5.59–12.73) in the three sampled counties, of which, no T. gondii-seropositive samples were detected in alpacas in Fanshi County. Gender differences in the T. gondii seroprevalence were observed. The overall Chlamydia seroprevalence was 13.94% (95% CI: 9.66–18.22), and there was a statistically significant difference in Chlamydia seroprevalence in alpacas between the two counties, Jiexiu and Fanshi. All serum samples tested negative for N. caninum and BTV antibodies, respectively. To our knowledge, this is the first report of T. gondii and Chlamydia seroprevalence in alpacas in China, which provides baseline information for controlling T. gondii and Chlamydia infection in alpacas in China.