Seroprevalence of Toxoplasma gondii infection in domestic dogs in an area from northwest of Iran: a cross-sectional study using immunodominant surface antigen 1 (SAG1).

Toxoplasma gondii is an obligate intracellular protozoan parasite that infects humans and animals. T. gondii surface antigen 1 (SAG1) is an appropriate antigen with high specificity and sensitivity for the detection of T. gondii infection in humans and animal hosts. The aim of this study was to determine the seroprevalence of T. gondii infection using SAG1 antigen (P30) in ownership dogs in Meshkin-Shahr district in the northwestern Iran. The sera samples were collected from 171 domestic dogs and tested using indirect ELISA (SAG1 antigen). The data were analyzed using SPSS software version 13. From a total of 171 dogs, 82 (48 %) of them were sero-positive. No statistical significant difference was seen between T. gondii infection and gender (P = 0.995). The highest sero-prevalence of rate was observed in >5 years animals; but no statistical significant difference was seen between T. gondii infection and age (P = 0.589). Our findings indicate that Toxoplasma seropositivity rate is high in ownership dogs in northwest of Iran. This is probably due to high exposure to contaminated food, soil, or water sources with sporulated Toxoplasma oocysts.

Evaluation of an indirect ELISA using a tachyzoite surface antigen SAG1 for diagnosis of Toxoplasma gondii infection in cats.

Toxoplasma gondii infection is very common in cats throughout the world. Most cats are subclinically infected and potentially fatal clinical disease occurs in some of them. The aim of this study is to develop an indirect enzyme linked immunosorbent assay (ELISA) test using an affinity purified tachyzoite surface antigen (SAG1) to detect T. gondii infection in cats. Six sero-negative kittens were used in this study; four kittens received 10(4) T. gondii tachyzoites of NED strain (type III) and the remaining two were used as uninfected controls. Serum samples were collected within 41 days and were evaluated for anti-T. gondii antibodies using indirect fluorescent antibody test (IFAT) and ELISA method. IgG antibodies were detectable at least from eight days after tachyzoites inoculation and an increasing pattern in both serum ELISA indices (SIns) and IFAT titers were detected. SIns were significantly different in sera of cats presenting different IFAT titers. In order to evaluate the performance of ELISA to detect anti-T. gondii antibodies of naturally infected cats, serum samples were also collected from household and stray cats and evaluated in the same way. IFAT was regarded as the standard test and sensitivity and specificity of the ELISA to detect the infection in naturally infected kittens were analyzed using two-graph receiver operating characteristic (TG-ROC) analysis. An area under curve (AUC) of 0.996 revealed the test as a highly accurate test with relative sensitivity and specificity of 100% and 96% for a cut-off value of 0.10 for SIn.

Neospora caninum and Leishmania infantum Co-Infection in Domestic Dogs (Canis familiaris) in Meshkin-Shahr District, Northwestern Iran.

BACKGROUND: Mediterranean visceral leishmaniasis (MVL) is an infectious disease that affects both human and animals. Domestic dogs (Canis familiaris) are principal reservoir hosts of MVL caused by Leishmania infantum. Dogs are definitive hosts for Neospora caninum and a risk factor for infecting intermediate hosts. The immunosuppression caused by visceral leishmaniasis (VL) can promote the occurrence of co-infections with other agents such as neosporosis. This study aimed to determine the frequency of co-infection of the both protozoan parasites in the endemic areas of VL from Meshkin-Shahr District, north-west of Iran. METHODS: Altogether, 171 serum samples were collected from domestic dogs of Meshkin-Shahr District by multistage cluster sampling from October 2008 to August 2009. The collected serum samples were tested for the detection of simultaneous infection of L. infantum and N. caninum using direct agglutination test (DAT) and indirect ELISA, respectively. RESULTS: Of the 171 domestic dogs, 27 (15.8%) and 52 (30.4%) were showed antibodies against L. infantum and N. caninum, respectively. Simultaneous infections of N. caninum and L. infantum was found in 16 (9.4%) of the dogs. In VL-positive and VL-negative dogs, N. caninum infection was found in 59.3% and 25.0%, respectively. A statistically significant difference was found between VL-positive and VL-negative dogs with N. caninum infection (P= 0.001). CONCLUSION: These findings indicate that Meshkin-Shahr District in northwestern Iran is an active focus of canine visceral leishmaniasis (CVL). Neospora caninum and L. infantum co-infection is prevalent in the area and infection by L. infantum seems to enhance susceptibility to N. caninum infection in domestic dogs.

Seroprevalence of Toxoplasma gondii Infection in Dogs in Tehran, Iran.

BACKGROUND: Toxoplasma gondii infects a wide range of animals; felines are definitive hosts and other animals including the dogs are intermediate hosts. The aim of this study was to determine the seroprevalence of T. gondii infection in dogs in Tehran, capital of Iran and to investigate possible associated risk factors. METHODS: Three hundreds ninety six serum samples were collected during 2007-8 from the dogs. Collected samples were tested using an indirect fluorescent antibody test (IFAT) in dilutions of 1:16 and more. All procedures were carried out in Shahrekord University, Iran. All the data were analyzed using SPSS software, qui square test with confidence interval of 0.95. RESULTS: From evaluated samples, 89 (22.47%) were positive in titers of at least 1:16. further evaluations in other dilutions showed positive results in dilutions of maximum 1:16, 1:32, 1:64, 1:128 and 1:256 in 38, 29, 15, 2 and 5 dogs respectively. Investigation of the role of risk factors showed no sex predisposition while infection rate was significantly higher in dogs older than one year old. Living places were of significant importance; infection rate was significantly higher in stray or guard dogs in compare with household dogs (P<0.05). CONCLUSION: Relatively high seroprevalence of T. gondii infection in dogs in Tehran shows high environmental contamination. It is recommended that the dogs with suspected clinical signs be tested for T. gondii infection.

Development of an indirect ELISA test using an affinity purified surface antigen (P38) for sero-diagnosis of canine Neospora caninum infection.

Neospora caninum is an intracellular protozoan that infects domestic and wild canids, as well as many warm blooded animals as shown by the isolation of viable parasites and the detection of parasite DNA in naturally infected hosts. N. caninum is described as a cause of neuromuscular disease and death in dogs. The dog is also known as a definitive host, shedding oocysts involved in the transmission of the infection to intermediate hosts. This study was conducted to develop an indirect ELISA test using an affinity purified 38 kDa N. caninum surface antigen (P38) for the sensitive and specific diagnosis of this infection in dog populations. To define a suitable cut-off, serum samples from 233 dogs were analyzed using an N. caninum-specific indirect fluorescent antibody test. All of these serum samples were subjected to the newly designed P38-ELISA. The Two-graph Receiver Operating Characteristics (TG-ROC) of the serum ELISA was determined to examine the performance of the test. TG-ROC analysis showed an area under curve (AUC) of 0.996 that indicates the test results being highly accurate. Optimal sensitivity and specificity (100% and 97.9%, respectively) were determined for SI(n) cut-off point of 0.23. To examine possible cross-reactions with other parasites affecting dogs, sera of dogs positive for antibodies against Toxoplasma gondii (n=17) and Leishmania infantum (n=11) infections were tested. These revealed negative results when tested in the new ELISA.

Development of an indirect ELISA test using a purified tachyzoite surface antigen SAG1 for sero-diagnosis of canine Toxoplasma gondii infection.

The aim of this study was to use affinity purified 30 kDa Toxoplasma gondii surface antigen (SAG1) in an indirect ELISA and to compare it with an existing indirect fluorescent antibody test (IFAT). 245 serum samples were collected from dogs from three adjacent Iranian provinces. IFAT examination revealed positive results in 73 dogs, with titers ranging from 1:16 to 1:1024. A suitable ELISA cut-off was determined by ROC analysis in comparison with IFAT. Results showed a relative sensitivity and specificity of 94.52% and 93.60%, respectively, for a cut-off value of 0.790 in the ELISA. No cross-reactivity was detected between antibodies against T. gondii and a closely related protozoan parasite, Neospora caninum, using this newly developed ELISA test.

Characterization of a repetitive DNA fragment in Hammondia hammondi and its utility for the specific differentiation of H. hammondi from Toxoplasma gondii by PCR.

Hammondia hammondi and Toxoplasma gondii are closely related protozoan parasites. Both species use felids as definitive hosts and a broad spectrum of warm-blooded animals as intermediate hosts. Morphologically and serologically, the two parasites are difficult to differentiate. While T. gondii is an important pathogen of humans and a broad range of other vertebrates, disease has not yet been associated with H. hammondi infection. The aim of the present study was to identify and characterize a repetitive DNA fragment in H. hammondi and to evaluate its suitability for diagnostic purposes. With two primers considered to be specific for a 529 bp repetitive DNA fragment in T. gondii, weak products were amplified by polymerase chain reaction (PCR) from genomic DNA from H. hammondi oocysts. These amplicons (of approximately 150, 300 and 450 bp) were sequenced. The 292 bp consensus sequence of these three fragments revealed 84% identity with parts of the 529-bp repeat in T. gondii. Based on this sequence, a pair of primers was selected which amplified products of 98 and 630 bp from genomic DNA from H. hammondi oocysts but not from DNA from T. gondii. The 630-bp product was purified and cloned into a plasmid vector and the consensus sequence determined from seven randomly selected clones; comparison of this sequence with those available in current databases for T. gondii revealed an 84.0-88.1% identity over a length of 529 bp. The sequence data obtained was used for the development of a sensitive PCR which is entirely specific for H. hammondi and incorporates an internal control. The sequence data for the repetitive DNA element of H. hammondi provides a foundation for the design of primers specific to T. gondii, and the future optimisation of conventional and real-time PCR assays for the specific diagnosis of toxoplasmosis in definitive and intermediate hosts.

Spontaneous manifestation of polycystic kidney disease following separation anxiety in a Persian cat.

A 4-year-old female Persian cat was referred with the history of separation from the owner. There was no clinical sign and everything had been reported as normal during the veterinary checkup just before separation and traveling. The history and clinical signs were fit to separation anxiety when the cat referred to us. Ten days after the diagnosis and starting of the treatment for separation anxiety, the cat was referred again with the clinical signs of chronic renal failure. Further assessments showed an inherited polycystic kidney disease. Spontaneous manifestation of polycystic kidney disease after separation anxiety indicate that this phenomenon may cause the chronic process of polycystic kidney disease to promote.

Lymphoma in Syrian hamster.

This study describes clinical and pathologic findings in a naturally occurring lymphoma in a Syrian hamster. Lymphoma; the most common tumor of hamster is viral induced tumor with veterinary importance. Clinical signs include emaciation, weakness, lethargy, diarrhea and some rectal bleeding. The present study describes clinical and pathologic findings of lymphoma in Syrian hamster. The disease is naturally occurred.

Serologic study of anti-Neospora caninum antibodies in household dogs and dogs living in dairy and beef cattle farms in Tehran, Iran.

A few studies have been done on the seroepidemiology of anti-Neospora caninum antibodies in dairy and beef cattle farms in Iran, which suggested the presence of N. caninum in these areas, but there is no published information directed on the presence or epidemiology of this organism in the dogs in Iran. To investigate anti-N. caninum antibodies in household dogs and dogs living in cattle farms, 100 blood samples were collected: 50 from dogs living in dairy and beef cattle farms and 50 from household dogs. Serum samples were screened for detection of anti-N. caninum IgG antibodies using indirect fluorescent antibody test (IFAT; > or = 50). Antibodies were seen in 10 (20%) of 50 household dogs and in 23 (46%) of 50 farm dogs. There were significant statistical differences in seropositivity between these two groups (P = 0.005). The IFAT antibody titers were as follows: 1:50 in seven dogs, 1:100 in eight dogs, 1:200 in six dogs, 1:400 in seven dogs, 1:800 in three dogs, 1:1,600 in one dog, and 1:12,800 in one dog. There were no significant differences in seropositivity between males and females. The positive results were increasing with age, and positive results were significantly different in the age group of older than 2 years compared to the dogs of age group under 1 year (P = 0.000) and 1-2 years (P = 0.007). The results confirm the exposure of household and farm dogs to N. caninum in Tehran and the higher rate of exposure for the dogs of dairy and cattle farms around Tehran.