Toxoplasmosis in rams: possible significance of venereal transmission

Detection of Toxoplasma gondii infection in semen of rams used for natural mating in commercial sheep farms in Tunisia

Toxoplasmosis, a parasitic infection, disrupts sexual functions resulting in decline in reproductive and economic performance in sheep. Lacking discernible symptoms, toxoplasmosis is difficult to detect and diagnose in infected animals. Here, to estimate the prevalence of natural infection by Toxoplasma gondii, we used PCR to amplify and detect T. gondii DNA in semen from 92 rams of three breeds from four regions in Tunisia and seroprevalence was determined using a commercial ELISA kit. From the PCR amplifications, 51.09 ± 10.21% of the rams were tested positive for T. gondii with an overall seroprevalence of 39.13 ± 9.97%. Risk factors including ram location and number of accomplished mating seasons significantly (p < .05) affected the sero- and molecular prevalence of T. gondii in semen but, there was a fair concordance between sero- and molecular prevalence (Kappa = 0.33). Sequences of T. gondii from five positive samples were 100% identical (same haplotype). Comparison of these sequences with those archived at the GenBank showed a sequence similarity range between 95 and 100%. The haplotype defining the five Tunisian sequences was similar to the one observed in chicken, cats, European pole cat and humans from Brazil, St Kitts and Nevis, Great Britain and Tunisia, respectively. This indicates its wide geographic distribution and non-species specificity. Our findings suggest a high prevalence of toxoplasmosis in Tunisian matting rams; further studies concerning its venereal transmission capacity are needed prior to recommending a systematic screening of T. gondii DNA in rams' semen used for both natural breeding and artificial insemination.

High Seroprevalence of Toxoplasma Gondii Infection in Female Sex Workers: A Case-Control Study

Through an age- and sex-matched case-control study, we sought to determine whether female sex workers have an increased risk of Toxoplasma gondii exposure and to determine the sociodemographic, work, clinical, and behavioral characteristics of these workers associated with T. gondii exposure. Female workers (n = 136) and controls (n = 272) were examined with enzyme-linked immunoassays (EIA) for the presence of anti-Toxoplasma IgG and IgM antibodies. IgM positive sera were additionally tested with enzyme linked-fluorescence immunoassay (ELFA). Anti-T. gondii IgG antibodies were found in 21 (15.44%) of 136 cases and in 10 (3.67%) of 272 controls (OR = 4.05; 95% CI: 1.84–8.89; P = 0.0001). Anti-T. gondii IgG levels higher than 150 IU/ml were found in 13 (9.6%) of 136 cases and in 8 (2.9%) of 272 controls (P = 0.007). Anti-T. gondii IgM antibodies were found in two cases and in six controls by EIA, but all were negative by ELFA. T. gondii seropositivity was associated with being born out of Durango State (OR = 10.47; 95% CI: 2.9–36.8; P < 0.01), injuries during sex work (OR = 6.30; 95% CI: 1.1–33.7; P = 0.03), and soil contact (OR = 4.11; 95% CI: 1.2–14.0; P = 0.02). This is the first report of an association of T. gondii infection and female sex workers.

Occurrence of Toxoplasma gondii DNA in sheep naturally infected and slaughtered in abattoirs in Pernambuco, Brazil

The aim of the present study was to assess the occurrence of antibodies to Toxoplasma gondii and to detect genomic DNA of the parasite in the reproductive organs, fetuses and fetal membranes of sheep in slaughterhouses in the state of Pernambuco, Brazil. The Indirect Immunofluorescence technique (IFA) was used for screening. The Polymerase Chain Reaction (PCR) was used to detect DNA of T. gondii in the animals that were positive in the serology. In the serology, 13/50 samples were positive and genomic DNA of T. gondii was detected in one uterus, tube, ovary, placenta and fetus (heart, brain and umbilical cord) sample from a sheep that was positive in the serology. The present study provides evidence of the occurrence of T. gondii DNA in the organs of the reproductive system, placenta and fetus of a naturally infected sheep.

Experimental vaginal infection of goats with semen contaminated with the "CPG" strain of Toxoplasma gondii

The objective was to characterize the transmission of Toxoplasma gondii in goats experimentally infected vaginally with semen contaminated with the CPG strain (genotype III). Ten female goats were randomly allocated into 2 groups (G1 and G2), each with 5 animals, and inseminated during estrus. Goats in G1 were inseminated with semen containing 1 × 10(5) tachyzoites, whereas those in G2 (control) were inseminated with semen free from tachyzoites (insemination = day 0). In G1, seroconversion (indirect immunofluorescence reaction) and DNA (polymerase chain reaction) in the blood was present in 4/5 and 3/5, respectively, from the 7th day. In G2, all goats were negative in all tests. Embryonic reabsorption occurred in 4 of 5 goats from G1 between days 21 and 49. In conclusion, artificial vaginal insemination with semen containing tachyzoites of T. gondii -infected goats and is a potential transmission route of this parasite through semen.

Detecção de Toxoplasma gondii no sêmen de ovinos naturalmente infectados

O objetivo deste trabalho foi estudar a eliminação de Toxoplasma gondii no sêmen de carneiros naturalmente infectados. Foram utilizados 65 reprodutores submetidos inicialmente à pesquisa de anticorpos anti-T. gondii por meio da técnica de imunofluorescência indireta (IFI). Os carneiros sorologicamente positivos foram submetidos à colheita de sêmen para detecção do DNA de T. gondii. Na sorologia observaram-se 6/65 (9,2%) carneiros positivos, enquanto no PCR nested de sêmen 4/6 (66,6%) carneiros foram positivos. Conclui-se que a detecção, por meio da técnica da PCR nested, da forma proliferativa de T. gondii no sêmen de carneiros naturalmente infectados, reforça a necessidade de se pesquisar sobre a possibilidade da transmissão horizontal do parasito via sêmen na espécie ovina.

Characterization of reproductive disorders in ewes given an intrauterine dose of Toxoplasma gondii tachyzoites during the intrauterine insemination

The aim of this study was to characterize the reproductive disorders in the acute and chronic phases in ewes experimentally infected with different doses of Toxoplasma gondii during artificial insemination occurred. Animals (n=41) were divided into three experimental groups: in the group 1 (G1, n=15), animals were inseminated using contaminated semen containing 6.5×10⁴ tachyzoites; in the group 2 (G2, n=15), animals were inseminated with contaminated semen containing 4×10⁷ tachyzoites and in the group 3 (G3, n=11), animals were inseminated using tachyzoite-free semen, serving as control group. Parasitemia and seroconversion were observed in 28 of 30 and 20 of 30, respectively, from the seventh day after infection. Embryonic reabsorption was observed in the acute phase in ewes from G1 and G2. Persistent anestrus, hydrometra, mucometra and follicular cysts were observed in the second phase of the experiment in animals from G1 and G2. Histopathological lesions similar to those of toxoplasmosis were found in the placentas. In conclusion, artificial insemination using semen containing experimentally added tachyzoites can establish toxoplasmosis in ewes and cause reproductive pathologies during the acute and chronic phases of the disease.

Artificial insemination of cows with semen in vitro contaminated with Neospora caninum tachyzoites failed to induce neosporosis

Neosporosis is a major cause of abortion in cattle all over the world. Congenital transmission as well as horizontal transmission by ingestion of oocysts has been described. The detection of Neospora caninum DNA in bull semen warrants the investigation of possible transmission through the use of contaminated semen. In this experiment four cows were artificially inseminated with frozen-thawed semen contaminated in vitro with viable N. caninum tachyzoites (group A) and four control cows were inseminated with tachyzoites-free frozen-thawed semen, from the same bull (group B). Serum samples were collected 15 days before the artificial insemination (AI) and at days 10, 14, 21, 28, 45, 60 and 75 post-insemination. All sera samples were tested for neosporosis by direct agglutination test (DAT). Three of the cows from group A had negative DAT titers (< or =1:20) in all of the samples, while the fourth cow from this group had a low titer of antibodies (1:80) at day 10, and became negative at day 45, suggesting a stimulation of the immune system by the tachyzoites placed in uterus, rather than the induction of an infection. All of the cows from group B had negative DAT titers (< or =1:20) in all of the samples. These results suggest that transmission of neosporosis by artificial insemination with frozen-thawed semen is an unlikely event.

Occasional detection of Neospora caninum DNA in frozen extended semen from naturally infected bulls

Recently, the presence of Neospora caninum DNA in semen from naturally infected bulls was reported. In the present work, the presence and quantification of N. caninum by PCR techniques in frozen extended semen straws from naturally infected bulls was investigated. A total of 20 seropositive and five seronegative bulls raised for reproductive purposes in an AI centre were used. Ten extended semen straws from each bull obtained at different time-points during the previous 2 years were selected for Neospora testing. Eight of the seropositive bulls (40%) studied showed at least one positive straw to N. caninum DNA and 14 of their 180 semen straws examined (7.8%) were found to be positive. In all positive samples, N. caninum DNA was consistently detected in the cell fraction and not in the seminal plasma. However, the parasite number in each positive straw was under the detection level of real-time PCR. In parallel, 10 semen straws from each of the five seronegative bulls were also analyzed by the nested-PCR and no N. caninum DNA products were obtained. In order to check the consistent presence of N. caninum in a positive semen batch, three additional semen straws from the same batch of each positive straw from three seropositive bulls were analyzed but N. caninum DNA was only detected in one straw from one bull. In conclusion, we report the sporadic detection of N. caninum DNA in semen straws of naturally infected bulls but the low frequency of contaminated semen straws and the low parasite load observed indicate a minor chance of bovine neosporosis transmission by AI.

Detection of Neospora caninum in semen of bulls

In cattle, transplacental infection is the main route of Neospora caninum transmission, but postnatal transmission by the oral uptake of sporozoite-containing oocysts shed by dogs may also be possible. Other routes of horizontal transmission, such as the venereal route, have not been investigated. In this study, we evaluated the presence of N. caninum DNA by a nested-PCR in fresh non-extended semen and frozen extended semen straws of five Holstein-Friesian bulls with naturally-acquired neosporosis. The infection status was assessed by an immunofluorescent antibody test (IFAT) and confirmed by immunoblotting (IB). Because of inhibitory components of semen, a protocol was developed to purify N. caninum DNA from bovine semen. Sporadically, N. caninum DNA was detected in non-extended fresh semen samples and frozen extended semen straws of the five seropositive bulls. In all positive samples, specific DNA was consistently found in the cell fraction of semen and not in seminal plasma. The parasite mean load in positive fresh semen samples determined by a real-time PCR was low oscillating between 1 and 2.8 parasites/ml of semen (maximum parasite load detected in one sample was 7.5 parasites/ml of semen). In parallel, another three similar but uninfected bulls acted as controls and no N. caninum DNA was amplified in any of their fresh and straw semen samples assayed. Whether venereal transmission plays a role in the spread of bovine neosporosis needs to be determined.

Prevalence and transmission of Toxoplasma gondii in wild brown rats, Rattus norvegicus

Prevalence of Toxoplasma gondii within 6 UK farmstead wild rat populations, and 1 population maintained within a captive cat-free environment for 2.5 years, was examined. The mean prevalence found was 35% (n = 235), which is more than 3 times as high as all other wild rat prevalence levels previously reported in the UK. There were no significant age, sex or site differences in prevalence between or within populations irrespective of habitat type or presence of cats. Toxoplasma was also maintained within the captive rat population in the absence of cats at a prevalence, intensity, age and sex distribution similar to that of the farmstead rat populations. These results suggest, firstly, that Toxoplasma can be perpetuated within wild rat populations without the sympatric presence of cats and secondly, that the congenital route is the predominant route of transmission in wild rats. This study concludes that wild rats represent a significant and persistent wildlife intermediate host reservoir for toxoplasmosis.