Seroprevalence of Toxoplasma gondii and Neospora caninum infection in dairy cows in subtropical southern China

Prevalence and risk factors of Toxoplasma gondii infection in dairy cattle from the Western Region of Thailand

In total, 901 dairy cow sera and data were collected from 51 farms in Nakhon Pathom, Ratchaburi and Kanchanaburi provinces (Western Region of Thailand). Serum samples were processed via the multispecies ELISA method to detect IgG antibodies against Toxoplasma gondii infection. The results demonstrated that the calculated true prevalence was 1.48% (95% CI, 0.64-2.75%) for the individual-level and 29.41% (95% CI, 18.71-43%) for the farm-level. The univariate risk factor analysis showed that the number of total owned cats, the presence of stray cats, and the frequency of cleaning per day were significant factors (p < 0.2). These three factors were subjected to logistic regression analysis, and the results revealed that the frequency of cleaning farms per day was a potential risk factor for T. gondii-seropositive farms (OR = 2.745, 95% CI, 1.15-8.69, p = 0.02). The frequency of cleaning might increase the T. gondii oocyst distribution within the barn area, thus increasing the possibility of infection. Our findings show that T. gondii continues to circulate in the dairy cow population in the western part of Thailand. The presence of cats on farms was not found to be associated with T. gondii infection, but the high frequency of cleaning the floor was, and contributed to the potential risk of infection.

Neospora caninum seroprevalence in water buffaloes in Guangxi, China

Neospora caninum is an important obligate intracellular apicomplexan parasite that causes spontaneous abortions in cattle and leads to huge economic losses to the farming industry. Although a high prevalence of N. caninum infection has been reported in Asia, data on the prevalence of water buffaloes in China remain unclear. To understand the seroprevalence of N. caninum infection in water buffaloes and its definitive host dogs in China, a total of 987 water buffalo sera from Guangxi Province were tested using an indirect enzyme-linked immunosorbent assay. We obtained an overall seroprevalence of 50.9% (502/987) for water buffalo samples. And the positive rate was higher in border cities (56.8%, 425/748) than in central cities (32.3%, 77/239). We further tested 240 serum samples from dogs in Guangxi and found an overall prevalence of 57.9% (139/240). The high prevalence of N. caninum infection in both dogs and water buffaloes was first reported in southern China, and these data will surely contribute to the prevention and control of the disease.

The global seroprevalence of Toxoplasma gondii infection in bovines: a systematic review and meta-analysis

Bovines, especially cattle, are considered as one of the main sources of Toxoplasma gondii infection for humans. A more comprehensive understanding of the occurrence of T. gondii is needed to provide a global perspective on the prevalence of T. gondii in bovines. Here, we present the results of the first systematic review and meta-analysis on the global T. gondii seroprevalence in bovines. Six databases (PubMed, ScienceDirect, Web of Science, Scopus, ProQuest and Google Scholar) were comprehensively searched for relevant studies published between 1 January 1967 and 30 May 2019. Among 7691 publications searched, 178 studies (from 50 countries) with 193 datasets were included in the meta-analysis. The global pooled and weighted seroprevalence of T. gondii among bovines was 17.91% [95% confidence interval (CI): 15.32–20.6]. Weighted prevalence based on the host was as follows: cattle 16.94% (95% CI: 14.25–19.81), buffalo 22.26% (95% CI: 16.8–29), yak 23% (95% CI: 14–33) and bison 8.1% (95% CI: 3.9–13.7). Continued monitoring on the status of T. gondii seroprevalence in bovines is essential. Study on the prevalence of T. gondii in the products of bovines such as milk, meat, etc., which are considered as the source of transmission of infection to humans, is recommended.

Public Health Significance of Toxoplasma gondii Infections in Cattle: 2009-2020

Toxoplasma gondii infections are common in humans and animals worldwide. The ingestion of food or water contaminated with oocysts excreted by infected cats or ingesting uncooked or undercooked meat containing tissue cysts of T. gondii are the 2 major modes of transmission of T. gondii. Viable T. gondii is more prevalent in pork and lamb than in beef. In the past decade, there have been many articles on the high seroprevalence in cattle, particularly from China. There is a report of an outbreak of acute toxoplasmosis in humans suspected to be linked to the ingestion of Artisan fresh cheese from cow's milk. There are conflicting reports concerning the rate of congenital transmission of T. gondii in cattle, especially from Brazil. In a report from Brazil, viable T. gondii was isolated from the blood of 1 of 60 pregnant cows slaughtered at an abattoir and from 1 fetus. The role of beef in the epidemiology of T. gondii infections is still not clear. Here, we review prevalence, persistence of infection, clinical disease, epidemiology, and public health risks of T. gondii infections in cattle from beef and cow's milk worldwide for the past decade.

Seroprevalence of Toxoplasma gondii in cattle in China from 2010 to 2019: A systematic review and meta-analysis

Toxoplasma gondii can infect almost all warm-blooded animals, including cattle, causing serious disease to animals and humans. Because cattle provide milk and meat for humans, an increasing number of people are raising cattle as a source of income. However, T. gondii may be transmitted to humans through the meat and milk of cattle. Although substantial relevant studies have been performed, overall data on the seroprevalence of T. gondii in cattle is still lacking. In this meta-analysis, 71 relevant studies were included from five databases that investigated the seroprevalence of T. gondii in cattle in China from 2010 to 2019. The overall pooled T. gondii seroprevalence in cattle was 10.1% (4217/39,274) in China. The seroprevalence of T. gondii was highest in southwestern China (21.6%, 727/3117) and lowest in northern China (4.5%, 185/1966). Due to the implementation of disease control measures during 2012 to 2020, the lowest positive rate was seen in the post-2017 subgroup of sampling years (5.8%, 170/3022). In the cattle breeds subgroups, the seroprevalence was highest in yaks (14.3%, 1695/10,777). Cattle aged ≥12 months (9.6%, 1248/12,438) had a higher seroprevalence than those <12 months (6.7%, 226/3132). Female cattle had a slightly higher seroprevalence (12.5%, 793/6670) than male cattle (11.7%, 418/3856). The seroprevalence in summer (11.8%, 517/4744) was the highest of all seasons. The present study shows that T. gondii is common in cattle in China. Therefore, monitoring measures and further research are needed to control T. gondii and improve public health.

Seroprevalence of canine neosporosis and bovine viral diarrhoea in dairy cattle in selected regions of Kenya

Neospora caninum is the causative agent for canine neosporosis (CN), a disease of potential zoonotic importance causing reproductive losses in cattle while causing neuromuscular disease in dogs. Bovine viral diarrhoea on the other hand is caused by the bovine viral diarrhoea virus (BVDV) and is one of the most important reproductive diseases of cattle worldwide. In Kenya, these infections are of economic importance due to the losses they cause in farms in which they are diagnosed or are subclinical. Such losses include reduced milk production, reduced conception, early embryonic deaths and abortions which lead to reproductive wastage. This study was conducted between April 2017 and July 2018 and determined the seroprevalence of neoporosis and BVD in select dairy herds in Kenya. Kakamega, Nandi and Makueni Counties from where dairy farms were purposively sampled were used. Serum samples were collected from randomly selected dairy animals aged at least 2 years in the selected farms and screened for BVDV and CN antibodies. Seroprevalence of N. caninum was 24.1% (n = 552) and BVD, 52.3% (n = 545) across all the counties. Co-infection where antibodies against the two infective agents were present was in 14.6% (n = 541) animals. Chi-square tests of association between prevalence and county were significant for BVD (p = .000) but not for neosporosis (p = .626). Further chi-square tests of association between the two infections were not significant (p = .105) neither were the associations of BVD (p = .575) and neosporosis (p = .626) on pregnancy status. These two diseases are rarely investigated as causes of bovine infertility. Detection of antibodies in the studied dairy herds underpins the need for enhanced surveillance by laboratories and for further studies to understand associated risk factors to formulate effective control strategies in dairy cattle to forestall abortions and production and reproduction losses.

Neospora caninum, A potential cause of reproductive failure in dairy cows from Northern Greece

Neospora caninum infection has been reported in a large number of intermediate hosts, such as ruminants, rabbits, mice, etc. but neosporosis has emerged as a serious disease in cattle and dogs worldwide. Abortions and other infertility issues have been reported in the infected cows, leading to great economic losses in farmers. The aim of our study was to assess N. caninum seroprevalence in dairy cattle from Northern Greece (region of Xanthi) by using the indirect fluorescent antibody technique. Blood samples were collected from 875 Holstein – Friesian dairy cows and tested for Neospora caninum antibodies. Among the cows that were studied, 184 (21.03%) were positive for N. caninum antibodies and concurrently their farms had a known previous history of infertility problems, such as abortions, increased number of artificial inseminations needed for conception, increased rate of returning to estrus and retention of fetal membranes.

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Neosporis is a common parasitosis in dairy cows.

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The number of abortions was significantly higher in seropositive cows.

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In seropositive cows the number of artificial inseminations was increased.

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The birth interval was much more longer in the N. caninum seropositive cows.

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Significant economic loss was observed in the infected farms.

Molecular detection of Neospora caninum from naturally infected four passeriforme birds in China

Neospora caninum is an intracellular protozoan infecting many domestic and wild animals. In the present study, the brain tissues of wild birds collected in Hunan province of China were examined by N. caninum specific nested PCR, targeting the Nc-5 gene and the internal transcribed spacer 1 (ITS-1) region of the nuclear ribosomal DNA. The prevalence of N. caninum was detected in 15.5% (37/239) of wild birds, including 20.5% (9/44) of the examined olive-backed pipit Anthus hodgsoni, 18.3% (24/131) of the examined tree sparrows Passer montanus, 7.9% (3/38) of the examined chestnut bunting Emberiza rutila and 3.8% (1/26) of the examined yellow-breasted bunting E. aureola. Phylogenetic analyses showed that N. caninum from different hosts and geographical origins are genetically diverse and can be further classified into two distinct groups. Our findings indicated that wild birds are potential source of N. caninum for other animals. To our knowledge, this is the first report of N. caninum infection in wild birds in China, which provides a foundation for the prevention and control of this parasite in China and elsewhere.

Meta-analysis of the prevalence and risk factors associated with bovine neosporosis

Neospora caninum is one of the main infectious agents that cause reproductive disorders in cattle. However, knowledge about the prevalence and causal factors of bovine neosporosis is needed in order to establish control measures. The purpose of this study was to estimate the pooled prevalence and determine the risk factors of bovine neosporosis using meta-analytic methods. Searches for data on N. caninum seroprevalence and potential risk factors were conducted in the PubMed, LILACS, and SciElo databases. The random effects model was used for the meta-analysis of the included studies. The pooled prevalence of N. caninum in cattle was 24% (95% confidence interval (CI), 19-29) in North and Central America, 24% (95% CI, 20-28) in South America, 18% (95% CI, 14-21) in Asia, 15% (95% CI, 12-18) in Europe, 13% (95% CI, 11-16) in Africa, and 8% (95% CI, 4-14) in Oceania. A significant correlation was found between N. caninum infection and abortion in cows (odds ratio (OR) = 2.66, 95% CI, 1.97-3.59). The following risk factors were signicantly associated with N. caninum seroprevalence: presence of dogs on the farm (OR = 2.84; 95% CI, 1.40-5.80) and the type of cattle production system, with dairy cattle being more susceptible to bovine neosporosis (OR = 1.60; 95% CI, 1.16-2.19) than beef cattle. The adoption of measures to prevent the dissemination of N. caninum in cattle herds is suggested, aiming to reduce the economic losses incurred to the dairy and beef industry.

Seroprevalence of Toxoplasma gondii in goats in Hunan province, China

Toxoplasma gondii infections are prevalent in animals and humans worldwide. In the present investigation, the seroprevalence of T. gondii in goats was investigated in Hunan province, subtropical China between March 2014 and December 2015. A total of 1,028 serum samples collected from 14 administrative regions of Hunan province were evaluated by the indirect hemagglutination test (IHAT) for the detection of specific antibodies. Antibodies to T. gondii were detected in 124 serum samples (12%). The T. gondii seroprevalence ranged from 1.7% to 19% among different regions in subtropical China, and the differences were statistically significant (p < 0.01). The results of the present survey indicated that T. gondii infection is prevalent in goats in Hunan, which poses a potential risk for human infection with T. gondii in this province.

Seroprevalence and genetic characterization of Toxoplasma gondii in masked palm civet (Paguma larvata) in Hainan province, tropical China

In the present study, the seroprevalence, risk factors and genotyping of Toxoplasma gondii in masked palm civet were investigated in tropical China. A total of 500 serum were collected from five administrative farms in tropical China, and assayed for T. gondii antibodies by modified agglutination test (MAT). The brain samples of 20 aborted fetuses were examined by semi-nested-PCR, and positive aborted fetuses (50%) were necropsied to collect the brain tissue for molecular and bioassay examinations. Genomic DNA was extracted from the 29 brain tissues of infected mice and T. gondii B1 gene was amplified using multilocus PCR-RFLP. Overall, 27.6% (95% CI: 23.682-31.518) of the animals was positive for T. gondii antibodies. Ages of masked palm civet was considered as a main risk factor associated with T. gondii infection. 4 DNA samples (13.8%) were positive for the T. gondii B1 gene. Three samples belong to ToxoDB#9, and one belongs to genotype the type II variant (ToxoDB genotype#3). Our results indicated that ToxoDB Genotype#9 has a distribution in masked palm civet that could be potential reservoirs for T. gondii transmission, which may pose a threat to human health.

Herd-level prevalence and associated risk factors for Toxoplasma gondii, Neospora caninum, Chlamydia abortus and bovine viral diarrhoea virus in commercial dairy and beef cattle in eastern, northern and northeastern China

Although the seroprevalence of Toxoplasma gondii, Neospora caninum, Chlamydia abortus and bovine viral diarrhea virus infection in cattle have been reported in some areas in China, most of them were conducted with small number of cattle samples and very limited districts and neglected the assessment of herd management factors associated with herd-level prevalence of these pathogen infections. Thus, from September 2013 to December 2014, a large-scale seroprevalence study was conducted to determine the animal-level and herd-level seroprevalence and identify herd-level risk factors associated with these pathogen infections in 4487 cattle from 134 herds in five provinces (Heilongjiang, Jilin, Liaoning, Shandong, Hebei) and Inner Mongolia Autonomous Region of China. At animal level, the true prevalence of antibodies against T. gondii, N. caninum, C. abortus and bovine viral diarrhoea virus (BVDV) was 10.48, 17.14, 11.92 and 50.10%, respectively. At herd level, the true prevalence of antibodies against T. gondii, N. caninum, C. abortus and BVDV was 27.16, 29.10, 37.31 and 40.30%, respectively. Multivariate analysis of these characteristics showed that source of water and presence of felids were significantly associated with T. gondii infection in the studied cattle herds. Source of water was significantly associated with N. caninum infection in the studied cattle herds. While herd size and management system were significantly associated with BVDV infection in the studied cattle herds, this is the first report of herd-level prevalence and associated risk factors of T. gondii, N. caninum, C. abortus and BVDV infection in cattle in China.

Secreted effectors in Toxoplasma gondii and related species: determinants of host range and pathogenesis?

Recent years have witnessed the discovery of a number of secreted proteins in Toxoplasma gondii that play important roles in host-pathogen interactions and parasite virulence, particularly in the mouse model. However, the role that these proteins play in driving the unique features of T. gondii compared to some of its nearest apicomplexan relatives (Hammondia hammondi and Neospora caninum) is unknown. These unique features include distinct dissemination characteristics in vivo and a vast host range. In this review we comprehensively survey what is known about disease outcome, the host response and host range for T. gondii, H. hammondi, and N. caninum. We then review what is presently known about recently identified secreted virulence effectors in these three genetically related, but phenotypically distinct, species. Finally we exploit the existence of genome sequences for these three organisms and discuss what is known about the presence, and functionality, of key T. gondii effectors in these three species.

Comparative characterization of microRNA profiles of different genotypes ofToxoplasma gondii

The present study compared the miRNA expression profiles of fiveToxoplasma gondiistrains, namely RH (Type I, ToxoDB10), TgXD (Type I, ToxoDB10), PRU (Type II, ToxoDB1), QHO (Type II, ToxoDB1) and TgC7 (ToxoDB9), by Solexa deep sequencing, bioinformatics analysis and real-time quantitative PCR. A total of 7, 15, 10, 12 and 10 miRNAs were found from RH, TgXD, PRU, QHO and TgC7 strains, respectively. Thirteen miRNAs were shared by three genotypes, with only one miRNA shared by all of the 5 strains and others shared by 2 or more strains. A large number of targets ranging from 1 to 185 were identified for commonly shared miRNAs and strain-specific miRNAs with complete or nearly complete complementarity. Functional prediction showed that these targets were mostly focused on catalytic activity (191 targets) and binding activity (183 targets). Nonetheless, the majority of targets and most of the miRNAs are related to the virulence or invasion proteins of different strains ofT. gondii, including ROP and MIC, as well as some other proteins, such as AMA1, GRA and RHO. The present study characterized comparatively the miRNA profiles of 3 different genotypes ofT. gondii, identified genotype-shared miRNAs and strain-specific miRNAs.