Toxoplasma gondii and Neospora caninum Infections in Stray Cats and Dogs in the Qinghai–Tibetan Plateau Area, China

Exploring similarities and differences between Toxoplasma gondii and Neospora caninum infections in dogs

Toxoplasma gondii and Neospora caninum infections in dogs are predominantly manifest asymptomatic. However, these infections can also present highly varied and potentially severe clinical signs. This is due to the parasites' ability to replicate in a number of cell types within the host organism, with N. caninum exhibiting a particular tropism for the central and peripheral nervous systems, and T. gondii targeting the central nervous system and musculature. In clinical practice, toxoplasmosis and neosporosis are often considered to be closely related diseases, despite their distinct epidemiological, clinical, diagnostic, and therapeutic characteristics. The present review analyses the similarities and differences between these two protozoan infections, since an accurate and timely aetiological diagnosis is essential for establishing effective therapeutic protocols and control strategies.

A 20-year serological survey of Toxoplasma gondii and Neospora caninum infection in dogs with neuromuscular disorders from urban areas in Argentina

Toxoplasma gondii and Neospora caninum infections may be associated with neuromuscular disorders in dogs. The aim of this study was to assess the seroprevalence to these protozoan parasites in dogs with neuromuscular disease from urban areas of Buenos Aires province, Argentina, over a period of 20 years, and to evaluate the association of seropositivity and antibody titres with different variables such as sex, breed and age. For this, a total of 7238 serum samples from urban owned dogs were analysed by the indirect fluorescence antibody test (IFAT) for specific IgG antibodies. The observed seropositivity rates were 35.7 % for T. gondii and 25.7 % for N. caninum. Crossbred dogs had a significantly higher seroprevalence for T. gondii than purebred dogs (41 % vs. 29.3 %), while a trend towards significance was observed for N. caninum, which was slightly higher in purebred dogs (26 % vs. 23.6 %). Seroprevalence for both parasites increased with age and was higher in older animals. Regarding the distribution of specific antibody titres, the most frequent IFAT T. gondii titre found was 100 and for N. caninum it was ≥800. For toxoplasmosis, there was no association with age group, and low titres (50, 100 and 200) predominated in all groups. However, for neosporosis, age and titres were significantly associated for one age group, with dogs under 12 months of age having a higher proportion of high titres (400 and 800). The trend in the seroprevalence for T. gondii is increasing over the years and lower antibody titres predominate in the dogs studied, which may be more related to the presence of chronic infections and not necessarily to the clinical signs of the animals. Despite the generally low titres observed for toxoplasmosis in this study, it is important to highlight the high seroprevalence found in our region, as dogs can act as sentinels of environmental contamination and as indicators of possible human infection. In the case of neosporosis, although the trend in seroprevalence in dogs with signs appears to be decreasing over the years, our work shows that higher antibody titres predominate, and are probably related to the clinical signs presented by the dogs. This study provides the most recent epidemiological data and serological profiles of T. gondii and N. caninum infections in a large number of canine sera from urban areas in Argentina, providing relevant information for clinical veterinarians and epidemiologists in order to understand the circulation of the parasites.

Serological and molecular survey of Toxoplasma gondii infection and associated risk factors in urban cats in Kunming, Southwest China

Toxoplasma gondii (T. gondii) is a worldwide zoonotic parasite that can infect almost warm-blood animals, including humans, which seriously affect the health of host. Cats are known to be the only definitive host of T. gondii and continuously excrete highly infectious oocysts. This parasite carried by the companion animals leads to a great public health risk. However, there is little information on epidemiology of T. gondii in urban cats in Kunming, Southwest China. In the present study, a total of 231 serum and fecal samples were collected in Kunming aera, and then seroprevalence of T. gondii IgG antibodies in serum and molecular investigation in feces were analyzed to elucidate T. gondii infection in urban cats. The results revealed that 168 of 231 cats (72.7%) were positive for T. gondii antibodies, and 1 of 74 cat feces (1.4%) also showed a positive PCR for T. gondii DNA. The positive fecal sample was sequenced and then phylogenetically analyzed, and the isolate of T. gondii in the present study was closely related to T. gondii strain CN. In addition, the food, water and age of cats were identified as the risk factor for seropositivity. Overall, our findings indicate the widespread occurrence of T. gondii infection in urban cats in Kunming, Southwest China and identify food, water and age are the risk factors associated with T. gondii infection, which can provide effective information for developing strategies to prevent and control this zoonosis.

Comparison of the performance of SAG2, GRA6, and GRA7 for serological diagnosis of Toxoplasma gondii infection in cats

Toxoplasmosis is an important zoonotic disease caused by Toxoplasma gondii that can infect almost all warm-blooded animals worldwide, including humans. The high prevalence of T. gondii infection and its ability to cause serious harm to humans and animals, especially immunodeficient individuals, make it a key public health issue. Accurate diagnostic tools with high sensitivity are needed for controlling T. gondii infection. In the current study, we compared the performance of recombinant SAG2, GRA6, and GRA7 in ELISA for the serological diagnosis of T. gondii infection in cats. We further investigated the antigenicity of recombinant dense granule protein 3 (rGRA3), rGRA5, rGRA8, and rSRS29A expressed in a plant-based, cell-free expression system for detecting antibodies in T. gondii-infected cats. In summary, our data suggest that GRA7 is more sensitive than the other two antigens for the serodiagnosis of T. gondii infection in cats, and GRA3 expressed in the cell-free system is also a priming antigen in serological tests for detecting T. gondii infection in cats.

An Antibody-Based Survey of Toxoplasma gondii and Neospora caninum Infection in Client-Owned Cats from Portugal

Toxoplasma gondii and Neospora caninum are obligate intracellular protozoan parasites infecting a wide range of hosts worldwide. However, information on the epidemiology of toxoplasmosis and neosporosis in cats from Portugal is limited. Thus, this study aims to evaluate anti-T. gondii and anti-N. caninum seroprevalence in client-owned cats from Portugal and to identify risk factors using a panel of well-characterized sera. A total of 183 domestic cats were sampled and screened for antibodies against T. gondii and N. caninum using commercial ELISA assays, and their owners answered an online questionnaire designed to obtain background information. The overall anti-T. gondii and anti-N. caninum seroprevalences were 13.1% (CI: 8.97-18.77) and 3.8% (CI: 1.87-7.68), respectively. Univariate analysis revealed that living strictly indoors was a significant protection factor (cOR: 0.053; CI: 0.005-0.627), and the presence of a chronic disease a significant risk factor (cOR: 3.106; CI: 1.062-9.082) to T. gondii seroprevalence. When performing multivariate analysis, only chronic disease (aOR: 57.527; CI: 1.7-1976.7) and seropositivity to N. caninum (aOR: 7.929; CI:0.8-82.9) were found to be a significant risk factor to anti-T. gondii antibodies. To the best of our knowledge, this is the first report of N. caninum seropositivity in cats from Portugal.

Seroepidemiological Survey of Anti-Toxoplasma gondii and Anti-Neospora caninum Antibodies in Domestic Cats (Felis catus) in Rolim de Moura, State of Rondônia, North Brazil

Epidemiological studies on infections by Toxoplasma gondii and Neospora caninum in cats in the North Region of Brazil are scarce. We intended to assess the seroprevalence in cats of anti-T. gondii and anti-N. caninum antibodies, as well as the associated risk factors that may lead them to contract these infections in Rolim de Moura, state of Rondônia, North Brazil. For this, blood serum samples of 100 cats from different regions of the city were evaluated. To assess possible factors associated with infections, epidemiological questionnaires were applied to tutors. The Immunofluorescence Antibody Test (IFAT) was performed for anti-T. gondii (cutoff 1:16) and anti-N. caninum (cutoff 1:50) antibodies. After identifying the positive samples, antibody titration was performed. The results showed the prevalence of 26% (26/100) of anti-T. gondii antibodies, with titration varying between 1:16 to 1:8192. There were no factors associated with the prevalence of anti-T. gondii antibodies in the multivariate analysis in this study. There was no occurrence of seropositive cats for anti-N. caninum. It was concluded that there was a high prevalence of anti-T. gondii antibodies in cats in Rolim de Moura, state of Rondônia, North Brazil. However, the evaluated animals did not present anti-N. caninum antibodies. Therefore, knowing that T. gondii has different transmission forms, we emphasize the importance of spreading more information to the population about cat's relevance in the T. gondii life cycle and how to avoid the parasite transmission and proliferation.

Application of Toxoplasma gondii-specific SAG1, GRA7 and BAG1 proteins in serodiagnosis of animal toxoplasmosis

Toxoplasmosis is a zoonotic disease caused by the obligate intracellular protozoan parasite T. gondii which is widely prevalent in humans and animals worldwide. The diagnosis of toxoplasmosis and distinguishing acute or chronic T. gondii infections have utmost importance for humans and animals. The TgSAG1, TgGRA7, and TgBAG1 proteins were used in the present study to develop the serological rSAG1-ELISA, rGRA7-ELISA and rBAG1-ELISA methods for the testing of T. gondii specific IgG and IgM antibodies and differentiating acute or chronic toxoplasmosis in 3733 animals, including Tibetan sheep, yaks, pigs, cows, cattle, horses, chickens, camels and donkeys from the Qinghai-Tibetan Plateau. The ELISA tests showed that the overall positivity of IgG antibody was 21.1% (786/3733), 15.3% (570/3733) and 18.2% (680/3733) for rSAG1-, rGRA7- and rBAG1-ELISA, respectively, and the positivity of IgM antibody was 11.8% (439/3733), 13.0% (486/3733) and 11.8% (442/3733) for rSAG1-, rGRA7- and rBAG1-ELISA, respectively. A total of 241 animals (6.5%) positive for all rSAG1-, rGRA7- and rBAG1-IgG were found in this study, and the 141 animals (3.8%) tested were anti-T. gondii IgM positive in all three ELISAs. Moreover, the 338, 284 and 377 animals were IgG positive in rSAG1 + rGRA7-, rBAG1 + rGRA7- and rSAG1 + rBAG1- ELISAs respectively, and the 346, 178 and 166 animals in rSAG1 + rGRA7-, rBAG1 + rGRA7- and rSAG1 + rBAG1-ELISAs were IgM positive respectively. The results confirmed that the application of SAG1, GRA7, and BAG1 recombinant antigens could successfully be used in the detection of specific IgG and IgM antibodies for distinguishing between acute or chronic T. gondii infections. It is inferred that the forms in which current animal species in the plateau area were infected with T. gondii, and the period of infection or the clinical manifestations of the current infections may be different. The present study provides substantial clinical evidence for the differential diagnosis of toxoplasmosis, and the classification of acute and chronic T. gondii infections.

Seroepidemiology of Neosporosis in Various Animals in the Qinghai-Tibetan Plateau

Neosporosis is a worldwide infectious disease caused by intracellular parasite Neospora caninum that is a major pathogen of abortion in cattle and neurological disorders in other hosts. However, limited data are available on animals exposed to N. caninum in the Qinghai-Tibetan Plateau Area (QTPA), and little is known about whether animals in the plateau area play an important role in the epidemiology of N. caninum. Therefore, indirect ELISAs based on a combination of NcSAG1 and NcGRA7 antigens were developed to examine both N. caninum-specific IgG and IgM antibodies in Tibetan sheep, yak, cow, pig, cattle, horse, chicken, camel, and donkey from the QTPA in this study. The results showed that all current species present- IgG and IgM-positive animals, and that the overall seroprevalence of N. caninum were 18.6 (703/3,782) and 48.1% (1,820/3,782) for the IgG and IgM antibodies, respectively. Further analysis found significant differences from different altitudes in IgG in Tibetan sheep and IgM in the yak. Hence, the present serological results indicate that the tested animal populations in the QTPA are suffering from N. caninum infections or have become carriers of N. caninum antibodies. To the best of our knowledge, this is the first report on current N. caninum-infected animals in the QTPA, the first epidemiology of neosporosis in cow and camel in China, and the first record of N. caninum IgM antibodies in all the surveyed animals in China. This study provides the latest valuable data on the epidemiology of neosporosis in China and in plateau areas of the world.