Molecular detection of toxoplasmosis in wild rats using loop-mediated isothermal amplification assay

Background and Aim

Toxoplasmosis is caused by the parasite Toxoplasma gondii. Cats are the only known hosts that excrete resistant oocysts. Wild rats serve as crucial reservoirs and intermediate hosts for T. gondii's survival and dissemination. Consuming soil and water containing oocysts can lead to illness. This study aimed to estimate the prevalence of toxoplasmosis in wild rats through molecular detection as an indicator of environmental contamination in Surabaya.

Materials and Methods

One hundred rats were collected from the three areas (housing, dense settlements, and traditional markets) and distributed into the five zones: West, East, Central, North, and South of Surabaya. Brain tissue samples were extracted using a Geneaid™ (New Taipei City, Taiwan) DNA isolation kit and analyzed through the loop-mediated isothermal amplification (LAMP) method.

Results

The study analyzed brain tissue from 100 wild rats, consisting of 77 Rattus tanezumi and 33 Rattus norvegicus, displaying 30% LAMP positivity. The study revealed that 30% (30/100) of wild rats tested were infected with T. gondii. The molecular prevalence rate in male rats was 32.35% (22/68), compared to females with 25% (8/32). 41.9% of the housing population, 33.3% of traditional markets, and 22.6% of dense settlements had the highest molecular prevalence. The high positive molecular rate at the trapping site can be attributed to cats and dense populations.

Conclusion

Thirty percentage wild rats were tested positive for toxoplasmosis in Surabaya, East Java, Indonesia using LAMP method. Implementing strict control and monitoring is crucial in preventing the transmission of diseases from wild rats to humans. It is necessary to carry out further research related to genetic analysis of T. gondii to determine the type of T. gondii that infects animals and humans in Surabaya through bioassay and molecular test.

Serological and molecular detection of Toxoplasma gondii and Neospora caninum in free-ranging rats from Nagpur, India

Toxoplasma gondii and Neospora caninum are cyst-forming coccidian parasites that infect both wild and domestic non-felids as intermediate hosts, with rodents serving as important reservoir hosts during their life cycles. This study was aimed at investigating T. gondii and N. caninum infections and identifying factors favouring T. gondii infection in free-ranging rats from India. A total of 181 rodents were trap-captured, and blood and brain samples were subsequently collected for serological and molecular examination of T. gondii and N. caninum. Antibodies against T. gondii and N. caninum were detected by MAT/NAT and IFAT in 13.8% (25/181) and 1.65% (3/181) of rodents, respectively. All three N. caninum samples positive by NAT/IFAT were also positive for ELISA, while for T. gondii, 19 of 25 MAT/IFAT positive samples were also positive for ELISA. The antibody titers (MAT/NAT/IFAT) of rodents seropositive for T. gondii ranged from 25 to 400, while those of rats seropositive for N. caninum ranged from 25 to 100. Also, using PCR, DNA from T. gondii (B1 gene) and N. caninum (NC5 gene) was found in 2.76% (5/181) of brain samples and 0.55% (1/181) of brain samples. All PCR positive samples were also seropositive. No mixed infections were observed in the serological and molecular detections. A Chi-square analysis revealed that older rats and rats living in urban areas are significantly associated with T. gondii infection; however, rodent species, gender, location, habitat types, and seasonality were statistically nonsignificant. Overall, this study demonstrated that T. gondii was widely distributed while N. caninum was less prevalent among free-ranging rats in the studied area.

Molecular detection of Toxoplasma gondii among commensal rodents from the Sahiwal division, Punjab, Pakistan

Toxoplasmosis is a zoonotic disease in humans and animals caused by the protozoan parasite Toxoplasma gondii. Rodents not only act as intermediate hosts for T. gondii but are also a significant source of T. gondii infection for other hosts. There is limited information about the prevalence of this protozoan within rodents in Pakistan. The current study was conducted to determine the prevalence of T. gondii in commensal rodents as well as associated risk factors. A total of 236 rats including Rattus rattus and Rattus norvegicus were captured from three districts of the Sahiwal division in Punjab province, Pakistan. Brain samples were collected from each specimen. Data was gathered about rodent species, gender, age, location, districts, seasonality, and habitat type. PCR assays were used to screen for T. gondii from the brain samples. A Chi-square analysis was used to investigate the association between positive samples and risk factors. A total of 236 rodent spleen samples were examined for detection of the B1 and SAG3 genes of T. gondii DNA by conventional PCR, and 14 (5.9%) were positive. T. gondii prevalence was higher in R. norvegicus (8.2%) compared to R. rattus (4.6%). All risk factors were statistically non-significant. This study provides evidence of T. gondii in rodents in the Sahiwal division and indicates that other animals and humans are at risk of infection.

The Detection of Toxoplasma gondii in Wild Rats (Rattus norvegicus) on Mink Farms in Shandong Province, Eastern China

Toxoplasma gondii is a worldwide distributed zoonotic pathogen that threatens public health. However, there have been limited data for T. gondii infection in wild rats (Rattus norvegicus) in China. In the present study, a total of 227 wild rats were captured from three mink farms to investigate T. gondii infection in Shandong Province, eastern China. The DNA was extracted from 25 mg rats' brain tissues and subjected to a PCR amplification by targeting to the T. gondii B1. In 227 wild rat samples, 18 samples (7.93%) were positive for T. gondii. Then, the positive samples were further genotyped based on eight genetic markers, including eight nuclear loci (SAG1, 5'-SAG2, and 3'-SAG2, alternative SAG2, SAG3, GRA6, c29-2, and L358) and an apicoplast locus (Apico) by using the multilocus PCR-restriction fragment length polymorphism technology. Of these samples, eight were genotyped at nine nuclear loci, and two were genotyped at eight nuclear loci, forming three known genotypes (ToxoDB no. 43, ToxoDB no. 91, and ToxoDB no. 189) and two new genotypes. The closest ToxoDB genotypes were observed in wild rats, suggesting the differences in the population structure of the T. gondii between breed farm animals and wild rats. These data revealed the genetic variability of T. gondii in wild rats on mink farms in Shandong Province, with possible implication for public health.

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.

Epidemiological Significance of Toxoplasma Gondii Infections in Wild Rodents: 2009-2020

Toxoplasma gondii infections are common in humans and animals worldwide. Rodents are one of the most important intermediate hosts for T. gondii because they are preyed on by cats, who in turn excrete the environmentally resistant oocysts in their feces and thus spread the infection. Information on T. gondii infections is spread in numerous reports and is not easily accessible to readers. Here, we review prevalence, persistence of infection, clinical disease, epidemiology, and genetic diversity of T. gondii infections in wild rodents worldwide. Data are tabulated by country, by each rodent species alphabetically, and chronologically. Recent genetic diversity of T. gondii strains in rodents is critically evaluated.

Prevalence and Risk Factors of Toxoplasma gondii Infection Among Five Wild Rodent Species from Five Provinces of China

Toxoplasma gondii, an intracellular zoonotic parasite, can infect humans and various animals worldwide. Wild rodents plan an important role as intermediate hosts of T. gondii. Some studies on T. gondii from wild rodents have been published, but the investigation data of T. gondii in wild rodents in China are limited. Therefore, brain tissue samples from 382 wild rodents in four provinces and one autonomous region of China were screened by PCR amplification of T. gondii B1 gene. Furthermore, the wild rodents were identified as five species based on their morphological characteristics, including Citellus dauricus (n = 35 from Heilongjiang), Lasiopodomys brandti (n = 81 from Inner Mongolia), Apodemus agrarius (n = 12 from Heilongjiang), Rattus norvegicus (n = 2 from Heilongjiang; n = 99 from Zhejiang; n = 54 from Shanxi), and Mus musculus (n = 99 from Guangxi). The overall prevalence of T. gondii in these wild rodents was 5.24% (20/382) in this study. At different regions, the highest prevalence of T. gondii was in Guangxi (12.12%) compared with other regions (0% in Heilongjiang; 2.47% in Inner Mongolia; 2.02% in Zhejiang; 7.41% in Shanxi). At different climates, the higher prevalence was found in temperate/mesothermal climates (7.07%) compared with continental/microthermal climates (3.26%). Also, the results showed that M. musculus had the highest prevalence of T. gondii infection (12.12%) among the rodent species sampled. Moreover, sampling year was significantly related to the prevalence of T. gondii in investigated wild rodents (p = 0.0117). This is the first report of T. gondii in wild rodents from Zhejiang, Guangxi, Shanxi, Heilongjiang provinces and Inner Mongolia autonomous region in China, providing the fundamental information for further prevention and control of toxoplasmosis in China.

Global Status of Toxoplasma gondii Seroprevalence in Rodents: A Systematic Review and Meta-Analysis

Toxoplasmosis is one of the most prevalent infections in humans and animals caused by the intracellular protozoan parasite Toxoplasma gondii (T. gondii). Rodents, as intermediate and reservoir hosts, play a key role in the maintenance and transmission of T. gondii. They can be contaminated and maintain the parasite in the form of cysts in their bodies, demonstrating an infection source for their offsprings, predators (particularly felids), and other animals. Therefore, the present systematic review and meta-analysis study was carried out to evaluate the global seroprevalence of T. gondii in these mammals. For achieving the purpose of the current study, six English databases (PubMed, Science Direct, Web of Science, Scopus, ProQuest, and Google Scholar) were systematically searched for related studies from 1970 to 2018. Finally, a total of 52,372 records were screened, 105 records including 26,221 rodents were incorporated in the present study. By random effect models, the overall seroprevalence was calculated at 6% (95% CI = 6-7%), with the highest amount was observed in Africa (24%) and South America (18%), and the lowest amount in Europe (1%). The subgroup data analysis by gender manifested that the prevalence of Immunoglobulin G antibodies did not differ between genders (P > 0.05). Due to the significant heterogeneity, meta-regression models were applied based on serological techniques and continental regions; however, the obtained values were not statistically significant (P = 0.480 and P = 0.295, respectively). The present study revealed a relatively low level of T. gondii seroprevalence in rodents; however, if they were the main food source for their predators, they would cause high transmission of T. gondii.

Serosurvey and molecular detection of the main zoonotic parasites carried by commensal Rattus norvegicus population in Tehran, Iran

Background

Rattus norvegicus are reservoirs for transmission of various zoonotic parasites, and they have become a threat to public health worldwide. Given the large number and the significant presence of R. norvegicus throughout the city of Tehran, this study aims to assess the frequency of zoonotic parasites carried by commensal rodents wandering in Tehran, Iran. The study considered the north, south, west, east, and center regions of Tehran for the purposes of this study. The serological tests were applied in order to detect effective antibodies against Trichomonas vaginalis (T. vaginalis), Babesia spp., and Cryptosporidium spp. using a commercial qualitative rat ELISA kit. The frequency of Toxoplasma gondii (T. gondii) was surveyed by using the conventional PCR method. Furthermore, nested PCR was employed to detect the presence of Giardia spp. and Leishmania spp. in commensal R. norvegicus dispersed in Tehran.

Results

Approximately, 76% of the 100 R. norvegicus tested were infected with at least one zoonotic parasite, indicating the significant frequency of parasites within the study areas. Seroreactivity against T. vaginalis, Babesia spp., and Cryptosporidium spp. was detected in 5%, 0%, and 1% of the R. norvegicus tested, respectively. T. gondii DNA was detected in 32 out of 100 (32%) R. norvegicus. In addition, Leishmania spp. and Giardia spp. DNA were found in 18 out of 100 (18%) and 76 out of 100 (76%) R. norvegicus investigated, respectively. T. vaginalis with 15% and T. gondii with 70% had the highest frequency of parasites among the R. norvegicus collected from the western and northeastern regions of Tehran, respectively. Moreover, Giardia spp. with 95% and Leishmania spp. with 30% had the highest frequency in the east and center districts, respectively.

Conclusion

The findings showed a wide geographical dissemination of Giardia spp., Toxoplasma gondii, and Leishmania spp. in R. norvegicus within five districts of Tehran. In contrast, other parasites such as Cryptosporidium spp. infection were rarely detected in Rattus populations. No evidence for the circulation of Babesia spp. was found in this study.

Molecular Detection and Genotyping of Toxoplasma gondii in Edward's Long-Tailed Rats (Leopoldamys edwardsi)

Toxoplasma gondii is an important zoonotic parasite infecting humans and various animals with a worldwide distribution. However, limited information is available on T. gondii infection in wild rats. The present study aimed to examine the prevalence and characterize the genotypes of T. gondii in wild rats in two regions of China. Brain tissues were collected from 111 Edward's long-tailed rats (Leopoldamys edwardsi) and 117 Bower's white-toothed rats (Berylmys bowersi) between November 2017 and January 2018. Genomic DNA was extracted and amplified by PCR targeting the T. gondii B1 gene. B1 gene-positive samples were genotyped at 10 genetic markers (SAG1, SAG2 [5', 3'] and [alternative], SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, and Apico) using multilocus nested polymerase chain reaction/restriction fragment length polymorphism. Six (5.41%, 6/111) Edward's long-tailed rats from Chongqing Municipality were positive for T. gondii B1 gene, whereas no T. gondii infection was detected in Bower's white-toothed rats (n = 117) from Guangdong province. T. gondii prevalence in female and male rats was 1.77% (2/113) and 3.48 (4/115), respectively. Four of the six positive DNA samples were completely genotyped at 10 genetic loci and were identified as ToxoDB#20. The present study revealed the occurrence of T. gondii infection in Edward's long-tailed rats. These findings raised public health concerning about T. gondii infection in wild rats. These results provide reference data for understanding the distribution of T. gondii genotypes in wild rats in China.

Prevalence and genotyping of Toxoplasma gondii in naturally-infected synanthropic rats (Rattus norvegicus) and mice (Mus musculus) in eastern China

Background

Synanthropic rats and mice share the same environment with humans and play an important role in epidemiology of toxoplasmosis; however, there is limited information about prevalence and genetic characterization of Toxoplasma gondii in synanthropic rats and mice in China.

Findings

In the present study, the prevalence and genetic characterization of T. gondii naturally infected synanthropic rodents (Rattus norvegicus and Mus musculus) were investigated in the urban area of Xuzhou city, Eastern China between June 2013 and August 2014. DNA from the brain of each animal was prepared and screened by specific PCR assay targeting 35-fold repeated B1 gene (B1-PCR). PCR positive DNA samples were further genotyped by multi-locus PCR-RFLP. Overall, out of 123 synanthropic rodents, 29 samples were positive by B1 gene-targeted PCR (23.6%). Of these, 7 out of 31 (22.3%) M. musculus were positive, whereas the positive rate of R. norvegicus was 23.9% (22/92). Multi-locus PCR-RFLP analysis reveals that seven PCR-positive samples were completely genotyped and they were identified as type China 1 (ToxoDB# 9).

Conclusion

To our knowledge, this is the first report of molecular detection and genetic characterization of T. gondii infection in synanthropic rodents in Eastern China. The results of the present study showed a high infection pressure of T. gondii exists in the environment and synanthropic rodents infected by T. gondii may be an important source of infection for cats and other animals.

Prevalence ofToxoplasma gondiiin localized populations ofApodemus sylvaticusis linked to population genotype not to population location

Toxoplasma gondiiis a globally distributed parasite infecting humans and warm-blooded animals. Although many surveys have been conducted forT. gondiiinfection in mammals, little is known about the detailed distribution in localized natural populations. In this study, host genotype and spatial location were investigated in relation toT. gondiiinfection. Wood mice (Apodemus sylvaticus) were collected from 4 sampling sites within a localized peri-aquatic woodland ecosystem. Mice were genotyped using standardA. sylvaticusmicrosatellite markers andT. gondiiwas detected using 4 specific PCR-based markers: SAG1, SAG2, SAG3 and GRA6 directly from infected tissue. Of 126 wood mice collected, 44 samples were positive giving an infection rate of 34·92% (95% CI: 27·14–43·59%). Juvenile, young adults and adults were infected at a similar prevalence, respectively, 7/17 (41·18%), 27/65 (41·54%) and 10/44 (22·72%) with no significant age-prevalence effect (P = 0·23). Results of genetic analysis of the mice showed that the collection consists of 4 genetically distinct populations. There was a significant difference inT. gondiiprevalence in the different genotypically derived mouse populations (P = 0·035) but not between geographically defined populations (P = 0·29). These data point to either a host genetic/family influence on parasite infection or to parasite vertical transmission.

Species or local environment, what determines the infection of rodents by Toxoplasma gondii?

Toxoplasmosis is largely present in rural areas but its spatial distribution in this environment remains poorly known. In particular, it is unclear if areas of high density of cats, the only hosts excreting Toxoplasma gondii, constitute foci of high prevalence. To improve our understanding of the spatial distribution of T. gondii in rural areas, we performed a serological survey in rodents from two villages in France. We trapped 710 rodents including commensal rats and meadow or forest voles and mice. The presence of T. gondii was examined using PCR, mice inoculation and modified agglutination test for antibodies (MAT). We conducted multivariate and discriminant analyses to identify biological, ecological or spatial variables that could explain T. gondii serology in rodents. We then used a logistic regression to assess the relative influence of each explanatory variable. Overall seroprevalence was 4·1%. Commensal-rats were more infected (12·5%) than non-commensal species (3·7%). However, the major determinant of the risk of infection was the distance to the nearest farm (OR = 0·75 for 100 m), which explained the risk in all species or non-commensal species only. We contrast the role of species characteristics and that of the local environment, and discuss the risk of environmental contamination for humans.

Seroprevalence of Toxoplasma gondii infection in dairy cattle in southern China

BACKGROUND

As an obligate intracellular parasite, Toxoplasma gondii can infect humans and almost all warm-blooded animals. The consumption of raw or undercooked beef and milk is considered a risk for T. gondii infection in humans. However, little is known of T. gondii infection in dairy cattle in metropolitan Guangzhou, southern China. This study was performed to determine the seroprevalence of T. gondii in dairy cattle in Guangzhou, southern China.

FINDINGS

Serum samples were collected from 350 dairy cattle on five farms in Guangzhou, China from 2009 to 2010, and all of the 350 serum samples were examined for specific antibodies to T. gondii by indirect hemagglutination antibody test (IHA). The overall seroprevalence of T. gondii in dairy cattle was 5.7% (20/350). Among these examined dairy cattle, dairy cattle which were < 6 year old or ≥ 5 year old had the highest seroprevalence of 12.5% followed by those dairy cattle which were < 5 year old or ≥ 4 year old (8%); dairy cattle with 3 pregnancies had the highest seroprevalence (11.5%), among the examined dairy cattle, although these differences were not statistically significant.

CONCLUSIONS

The results of the present survey indicate that T. gondii infection is prevalent in dairy cattle of all age ranges in Guangzhou, southern China, which may be a risk factor for human infection with T. gondii in this region.Dong-Hui Zhou and Fu-Rong Zhao contributed equally.