MAT Titer Research Articles

Preliminary study on the status of feline leptospirosis in Kerala

Leptospirosis is a disease of zoonotic importance in worldwide scenario and is caused by the infection of Leptospira species. The present study was undertaken to estimate the seropositivity of leptospirosis in cats of Kerala. A total of 200 serum samples were collected from apparently healthy cats from different parts of Kerala such as Thiruvananthapuram, Kollam, Alappuzha, Pathanamthitta, Kottayam, Thrissur, Ernakulam, Malappuram, Kozhikode, Wayanad, and Kannur. Among these samples, 12 samples (6 %) were found to be positive with the MAT titre above 1:20. The serovar identified in this study was serovar Djasiman, Autumnalis, Icterohaemorrhagiae, Australis, Grippotyphosa, and Hardjo. The highest prevalence in cat was for serovar Djasiman (50%) followed by serovar Autumnalis (25%). The majority of cats were crossbreds, males and in age groups between one and two years (58.33%). The majority of animals had both indoor with outdoor access, the presence of rodents and other animals in the household or surroundings.

Treatment of Bovine Leptospirosis with Enrofloxacin HCl 2H2O (Enro-C): A Clinical Trial.

Simple SummaryUnlike standard enrofloxacin, its crystal solvate enrofloxacin HCl-2H2O (enro-C) exhibits favorable pharmacokinetics and PK/PD ratios compatible with its use as a treatment during the clinical phase of leptospirosis in cattle. Hence, a clinical trial was conducted in cattle located either in the highlands (HL) or the tropics (TL). A high dose of 15 mg/kg day IM of enro-C administered over 5 days was compared against the conventional treatment with streptomycin/penicillin-G. The cows treated with enro-C became PCR negative: 87.5% and 78.94% on day 5, and 92.85% and 94.73% on day 28 (in the HL and TL, respectively). For streptomycin/penicillin-G, the same values were 65.45% and 70.90% on day 5 and 73.68% in both scenarios on day 28. In both groups, the microagglutination titers dropped on day 28, and gestation rates were statistically indistinguishable between the groups. This is the first report of successful treatment with fluoroquinolone in treating bovine leptospirosis.Pharmacokinetics/pharmacodynamics ratios of enrofloxacin HCl-2H2O (enro-C) in cows to treat bovine leptospirosis prompted this clinical trial in the highlands (HL) and the tropics (TL) in Mexico. In the HL, 111 Holstein-Friesian cows were included and 38 F1 Zebu–Holstein/Friesians in the TL. Affected cows were randomly divided into two treatment groups, both in the HL and TL. PCR and MAT tests were performed before and after treatment. Treatments in both groups were administered for 5 d with either IM injections of enro-C or streptomycin/penicillin-G. Reproductive performance data were gathered for 90 d. The cows treated with enro-C became PCR negative: 87.5% and 78.94% on day 5, 92.85% and 94.73% on day 28 (in the HL and TL, respectively). For streptomycin/penicillin-G, the same values were 65.45% and 70.90% on day 5, and 73.68% twice on day 28 in the HL and TL, respectively. In both groups and geographical settings, the MAT titers dropped on day 28 but remained above reference values usually considered negative. The gestation rates were: 86.53% and 79.06% and 88.88% and 87.5% for the HL and TL, either with enro-C or streptomycin/penicillin-G, respectively. This is the first report of successful treatment with a fluoroquinolone derivative in treating bovine leptospirosis with a high bacteriological cure rate.

Longitudinal Testing of Leptospira Antibodies in Horses Located near a Leptospirosis Outbreak in Alpacas.

Simple SummaryThe objective of this study was to look at antibodies in repeated blood samples from horses kept near, or on, a farm where Leptospirosis was diagnosed in a herd of alpacas, resulting in kidney disease and abortion in the alpacas. Blood samples from horses in New Zealand have previously shown approximately 25% have antibodies to Leptospira, although there are few reports of clinical disease. Seven of twelve horses had positive antibody results during the current study, and two horses had high concentrations of antibodies in their blood together with evidence of leptospires in their urine. These results suggest the two horses could have been actively infected with Leptospira, and potentially be at risk of transmitting the disease to humans and other animals on the property. It was not able to be determined if there was a direct association between the positive horses in this study and the outbreak in alpacas. Potentially, there could have been a common exposure for both horses and alpacas, or one group may have infected the other. The potential risk of horses shedding leptospires that could infect humans, or other species, should not be overlooked in New Zealand.The objectives of this study were to determine if horses located near an outbreak of leptospirosis in alpacas had Leptospira titres indicative of a previous or current infection and, if so, to determine the magnitude in change of titres over time. Further, the objective was to determine if horses with high titre results were shedding Leptospira in their urine. Blood samples were collected from twelve horses located on or next to the farm with the outbreak in alpacas, on day zero and at four subsequent time points (two, four, six and nine weeks). The microscopic agglutination test was used to test sera for five serovars endemic in New Zealand: Ballum, Copenhageni, Hardjo, Pomona and Tarassovi. A reciprocal MAT titre cut-off of ≥1:100 was used to determine positive horses. Seven out of twelve horses (58%) were positive to at least one serovar during one of the time points. Two horses recorded titres of ≥1600, one for both Pomona and Copenhageni and the other for Hardjo, and these two horses were both PCR positive for Leptospira in their urine samples. For five out of seven horses, the titres either remained the same or changed by one dilution across the sampling time points. The study confirmed endemic exposure to five endemic Leptospira serovars in New Zealand in a group of horses located near a confirmed leptospirosis outbreak in alpacas.

Exposure of pelagic seabirds to Toxoplasma gondii in the Western Indian Ocean points to an open sea dispersal of this terrestrial parasite.

Toxoplasma gondii is a protozoan parasite that uses felids as definitive hosts and warm-blooded animals as intermediate hosts. While the dispersal of T. gondii infectious oocysts from land to coastal waters has been well documented, transmission routes to pelagic species remain puzzling. We used the modified agglutination test (MAT titre ≥ 10) to detect antibodies against T. gondii in sera collected from 1014 pelagic seabirds belonging to 10 species. Sampling was carried out on eight islands of the Western Indian Ocean: Reunion and Juan de Nova (colonized by cats), Cousin, Cousine, Aride, Bird, Europa and Tromelin islands (cat-free). Antibodies against T. gondii were found in all islands and all species but the great frigatebird. The overall seroprevalence was 16.8% [95% CI: 14.5%-19.1%] but significantly varied according to species, islands and age-classes. The low antibody levels (MAT titres = 10 or 25) detected in one shearwater and three red-footed booby chicks most likely resulted from maternal antibody transfer. In adults, exposure to soils contaminated by locally deposited oocysts may explain the detection of antibodies in both wedge-tailed shearwaters on Reunion Island and sooty terns on Juan de Nova. However, 144 adults breeding on cat-free islands also tested positive. In the Seychelles, there was a significant decrease in T. gondii prevalence associated with greater distances to cat populations for species that sometimes rest on the shore, i.e. terns and noddies. This suggests that oocysts carried by marine currents could be deposited on shore tens of kilometres from their initial deposition point and that the number of deposited oocysts decreases with distance from the nearest cat population. The consumption of fishes from the families Mullidae, Carangidae, Clupeidae and Engraulidae, previously described as T. gondii oocyst-carriers (i.e. paratenic hosts), could also explain the exposure of terns, noddies, boobies and tropicbirds to T. gondii. Our detection of antibodies against T. gondii in seabirds that fish in the high sea, have no contact with locally contaminated soils but frequent the shores and/or consume paratenic hosts supports the hypothesis of an open-sea dispersal of T. gondii oocysts by oceanic currents and/or fish.

Vaccine Preperative Trial for Leptospirosis and their Pathological, Immunological Study by Serum Electrophoresis

Leptospirosis is a fatal infectious disease caused by different serovars of Leptospira spirochetes affecting humans and animals. In the present study, the trials of the whole-cell killed formalin treated monovalent vaccine using Leptospira icterohaemorrhagiae and trivalent vaccine using Leptospira icterohaemorrhagiae, Leptospira louisiana, and Leptospira hebdomadis were studied. The serum electrophoresis studies were done after administration of the vaccine into the experimental albino mice along with the booster dose of the vaccinated serum by densitometric readings. Similarly, the pathological observations were made by dissecting the virulent mice, vaccinated mice, and comparing them with the control mice. The MAT titre was also studied after the booster dose administration of the vaccinated serum. The monovalent and trivalent whole-cell killed formalin treated vaccines shows significant raise in the total proteins, albumin, globulin, α 1 globulin, α 2 globulin, β globulin and γ globulins of the serum as well as increase in significant levels in the antibody levels after the administration of the booster dose at an interval of 14 days.
 Keywords: Leptospira, Whole-cell killed formalin treated vaccine, Immunological study, Pathological study, Serum electrophoresis.

High Seroprevalence But Low Rate of Isolation of Toxoplasma gondii from Wild Elk (Cervus canadensis) in Pennsylvania

Toxoplasma gondii infections are prevalent in most warm-blooded animals worldwide. During the 2018 November hunting season in Pennsylvania, fresh (unfixed, not frozen) samples obtained from 99 harvested elk (Cervus canadensis) were tested for T. gondii infection. Antibodies to T. gondii were detected in 69 of 99 (69.7%) elk tested by the modified agglutination test (MAT, 1:25 cut-off). Tongues and hearts from 16 elk with high MAT titers (>1:200) were bioassayed for T. gondii by inoculation in outbred Swiss Webster (SW) and interferon-gamma gene knockout (KO) mice. Viable T. gondii was isolated from tongues of 2 elk with MAT titers of 1:200 and 1:3,200. Toxoplasma gondii from both isolates were successfully propagated in cell culture. Genetic typing on DNA extracted from culture-derived tachyzoites using the PCR restriction fragment length polymorphism with 10 genetic markers (SAG1, SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, and Apico) revealed that both isolates belonged to ToxoDB PCR-RFLP genotype #5 that is widely prevalent in wildlife in the United States. Our results suggest that elk may clear T. gondii organisms from their tissues.

Evidence of Leptospira species and their significance during reintroduction of Eurasian beavers (Castorfiber) to Great Britain

The Scottish Beaver Trial (SBT) reintroduced the Eurasian beaver (Castor fiber) in 2009 using wild-caught Norwegian beavers. This included a six-month prerelease quarantine in Devon, England. The International Union for...

Seroprevalence, frequency of leptospiuria, and associated risk factors in horses in Kansas, Missouri, and Nebraska from 2016-2017.

Leptospirosis is a worldwide veterinary and public health concern, and well recognized infectious disease of horses. Seroprevalence rates vary with geography, but many studies have confirmed a high exposure rate. The correlation between seropositivity and shedding status has not been made in horses, however. The aims of this study were to use semi-nested PCR on urine from apparently healthy horses to determine period prevalence of leptospiral shedding and to correlate these findings with MAT results to establish associations with client based survey data regarding horse management and environment. Serum and free-catch urine were collected from 204 healthy horses between May 2016-December 2017. Serum was used to determine GGT, creatinine concentrations, and six serovar MAT. Urine samples were submitted for PCR testing of leptospiral 23S rRNA. Client consent and survey data were collected for all subjects. Potential risk factors included drinking water source, exposure to livestock and dogs, geographical location, season, and precipitation. Two horses were positive on urine PCR for leptospirosis (shedding prevalence 1%), yet only one had a high reciprocal MAT titer of ≥ 800. Both horses were negative on urine PCR one month later without treatment. Approximately 77% of horses (157/204) were seroreactive (MAT reciprocal titer ≥ 100) with titers to serogroup Australis detected more frequently than others (47.5%; (97/204)). Apparently healthy horses infrequently shed Leptospira spp. in urine, yet seroreactivity in clinically normal horses is high (77%), confirming high exposure rates to Leptospira spp. in the Central Midwest.

High incidence of leptospirosis in an observational study of hospital outpatients in Vanuatu highlights the need for improved awareness and diagnostic capacities.

BackgroundEstimates of leptospirosis morbidity identified Oceania as the region with highest burden. Besides Australia and New Zealand, Oceania is home of Pacific Island Countries and Territories, most of which are developing countries facing a number of challenges. Their archipelago geography notably affects health infrastructure and access to healthcare. Although human leptospirosis was formerly identified in Vanuatu, there is a lack of knowledge of this disease in the country. We aimed to identify leptospirosis in outpatients visiting the hospital.Methodology/Principal findingsWe conducted a clinical study to investigate leptospirosis as a cause of non-malarial acute febrile illness in Vanuatu. A total 161 outpatients visiting the outpatient clinics at Port Vila Central Hospital for internal medicine were recruited over 20 month. We showed that leptospirosis significantly affects humans in Vanuatu: 12 cases were confirmed by real-time PCR on acute blood samples (n = 5) or by high serology titers evidencing a recent infection (MAT titer ≥800 or ELISA≥18 Units, n = 7). A high rate of positive serology was also evidenced, by MAT (100<titer<800, 9 patients) or ELISA IgM (ELISA≥12 Units, 20 patients, including 6 also positive in MAT), showing frequent exposure to pathogenic leptospires, notably from serogroup Australis.Conclusions/SignificanceThe high numbers of both seropositive patients and acute leptospirosis cases observed in outpatients visiting Port Vila Central Hospital suggest a high exposure to pathogenic Leptospira in the population studied. The MAT serology pointing to serogroup Australis as well as exposure history suggest that livestock animals largely contribute to the burden of human leptospirosis in Vanuatu. The analysis of residential and travel data suggests that the risk might even be higher in other islands of the Vanuatu archipelago. Altogether, our study emphasizes the need to increase awareness and build laboratory capacity to improve the medical care of leptospirosis in Vanuatu.

Isolation of viable Toxoplasma gondii, molecular characterization, and seroprevalence in elk (Cervus canadensis) in Pennsylvania, USA

Toxoplasmosis is a worldwide zoonosis. The ingestion of uncooked/undercooked meat and consumption of water contaminated with Toxoplasma gondii oocysts excreted by felids are the main modes of transmission of this parasite. T. gondii has been reported in multiple cervid species; however, little is known of the parasite in North American elk (Cervus canadensis). In the present study, antibodies to T. gondii were detected in serum of wild elk from Pennsylvania collected during 2013–2016 by the modified agglutination test (MAT, cut-off 1:25); 221 of 317 (69.7%) had MAT titers of 1:25 in 19, 1:50 in 28, 1:100 in 34, and 1:200 or higher in 140. Thus most (44.1%) elk had relatively high titers. Seroprevalence was slightly higher in males (76.9%) than females (67.5%, not statistically significant, Chi-square tests, P<0.0001) and was higher in adults (76.5%) than yearlings (46.4%, Odds ratio 3.82; 95% CL 1.72–8.47; P=0.001) or calves (21.7%, Odds ratio 12.58; 95% CL 4.51–35.10; P<0.0001). Annual seroprevalence was relatively stable throughout the period tested and ranged from 66.6% to 72.2%. Of the 101 elk harvested in 2016, hearts were bioassayed from 20 elk and tongues were bioassayed from 56; all tongue samples were negative. Viable T. gondii was isolated from hearts of two female elk, one of these was a seronegative adult and the other was a calf with no serum available for testing. Both T. gondii isolates were cultivated in cell culture and DNA derived from tachyzoites was characterized using the PCR-RFLP markers including SAG1, SAG2 (5′- 3′SAG2 and altSAG2), SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, and Apico. One isolate belongs to ToxoDB PCR-RFLP genotype #2 and the other is genotype #5. Both genotypes are frequently identified in animals in North America.

Canine leptospirosis in Switzerland—A prospective cross-sectional study examining seroprevalence, risk factors and urinary shedding of pathogenic leptospires

Leptospirosis is an important worldwide zoonosis. While human leptospirosis remains rare in Switzerland, the incidence of canine leptospirosis is unusually high compared to other European countries. The aims of this cross-sectional study were to determine the exposure of asymtomatic dogs to pathogenic Leptospira in Switzerland, to characterise risk factors associated with seropositivity and to determine the prevalence of urinary shedding. Sampling was stratified to cover the whole of Switzerland. Sera were tested by microscopic agglutination test for antibodies against a panel of 12 serovars. Urine was tested for pathogenic Leptospira using a LipL32 real-time PCR. Of 377 sera, 55.7% (95%CI 51.2–60.7) showed a reciprocal MAT titre of ≥1:40 and 24.9% (95%CI 20.7–29.4) of ≥1:100 to at least one serovar. Seropositivity (MAT ≥1:100) was most common to serovars Australis (14.9%; 95% CI 11.4–18.6) and Bratislava (8.8%; 95%CI 6.1–11.7), followed by Copenhageni (6.1%; 95%CI 3.7-8.5), Canicola (5%; 95%CI 2.9–7.4), Grippotyphosa (4.5%; 95%CI 2.7–6.9), Pomona (4%; 95%CI 2.1–6.1), Autumnalis (2.7%; 95%CI 1.3–4.2) and Icterohaemorrhagiae (1.6%; 95%CI 0.5-2.9). In unvaccinated dogs (n=84) the prevalence of a MAT titre ≥100 was 17.9% (95%CI 10.7–26.2), with a similar distribution of reactive serovars. Variables associated with seropositivity (≥1:40) to any serovar included age (OR 1.29/year; 95%CI: 1.1–1.5) and bioregion with higher risks in the regions Northern Alps (OR 14.5; 95%CI 2.2–292.7), Central Plateau (OR 12.3; 95%CI 2.0–244.1) and Jura (OR 11.2; 95%CI 1.7–226.7) compared to Southern Central Alps. Dogs living with horses were significantly more likely to have antibodies to serovar Bratislava (OR 4.68;95%CI 1.2–17.2). Hunting was a significant risk factor for seropositivtiy to serovar Grippotyphosa (OR 8.03; 95%CI 1.6–30.8). Urine qPCR positivity was uncommon (1/408 dogs; 0.2%; 95% CI0–0.7). These results demonstrate that dogs in Switzerland are commonly exposed to pathogenic Leptospira; however, the risk of dogs contributing to the spread of Leptospira in the environment appears low.

Development of leptospiral outer membrane protein-based dot-ELISA assays and immunoprofiling for diagnosis of acute canine leptospirosis

The present study was carried out to evaluate outer membrane protein (OMP)-based relatively simple dot-ELISA assays for the diagnosis of acute canine leptospirosis and to identify the differential expression of leptospiral OMPs for identifying the markers of acute infection, if any. Among 91 canine serum samples screened, 63 samples were found to be positive by MAT. All the samples were tested by OMP-based IgM and IgG dot ELISAs. The sensitivities of IgM and IgG dot ELISA in comparison to MAT (titer: ≥1:400) were found to be 100%, whereas the specificities were found to be 89.71% and 45.31%, respectively. IgM and IgG immunoblotting of OMPs was standardized and tested with the MAT-positive samples. IgM immunoblotting of leptospiral OMP revealed proteins of 18, 21, and 32 kDa as major reactors. With IgG, proteins of 32, 41, and 66 kDa were recognized as major reactors and an 86-kDa protein was identified as a minor reactor. The 32-kDa protein was the predominant reactor in both IgM and IgG immunoblots. Thus, a combination of 18-, 21-, and 32-kDa proteins could be a good choice for the detection of IgM antibodies indicative of acute infection while that of 32-, 41-, and 66-kDa proteins could be employed for seroepidemiological studies.

Seroepidemiologic study on the prevalence of Toxoplasma gondii and Trichinella spp. infections in black bears (Ursus americanus) in Pennsylvania, USA

The protozoan Toxoplasma gondii and the metazoan Trichinella spp. infect virtually all warm-blooded animals, including birds, humans, livestock, and marine mammals. Both parasitic infections can cause serious illness in human beings and can be acquired by ingesting under-cooked meat harboring infective stages. Approximately 3500 black bears (Ursus americanus) are legally-harvested each year in Pennsylvania, USA during the November hunting season. Among animals found infected with T. gondii, the prevalence of T. gondii is the highest among black bears in the USA; however, little is currently known of epidemiology of toxoplasmosis in this host species. Serum samples were collected during the winters of 2015 and 2016 from adult female bears and their nursing cubs or yearlings while they were still in their dens. Additionally, archived sera from bear samples collected throughout the year, including hunter-harvested bears in November and trapped bears in the summer, were serologically tested. Antibodies to T. gondii were assayed by the modified agglutination test (MAT, cut-off 1:25) and antibodies to Trichinella spp. were assayed using a commercial enzyme-linked immunosorbent assay (ELISA). Overall, T. gondii antibodies were found in 87.6% (206/235) of adults, and 44.1% (30/68) of yearlings. In March 2015/2016 sampling, antibodies to T. gondii were found in 94% (30/32) adult female bears while in their den. Antibodies were detected in 5% (3/66) of the nursing cubs in the dens of these sows. One positive cub had a MAT titer of 1:160 and two were positive at the 1:25 dilution but not at 1:50. The adult females of these cubs had MAT titers ranging from 1:400 to 1:3200. Antibodies to Trichinella spp. were found in 3% (6/181) of adults and 3.6% (1/28) of yearlings; these 7 bears were also seropositive for T. gondii. No antibodies to Trichinella spp. were detected in the sera of 44 nursing cubs tested. The finding of T. gondii antibodies in only 3 of 66 cubs, and higher antibody titers in their respective sows indicates that the colostrally-acquired antibodies wane to undetectable levels by 8–10 weeks, while the cubs are still in the den. The results indicate that there is no transplacental transmission of T. gondii, that antibodies acquired from colostrum are largely undetectable by the time cubs emerge from the den, and nearly that 50% of bears acquire infection postnatally by 10 months of age. This is the first report of disappearance of transcolostral antibodies of any infection in bears.

A Rapid In-Clinic Test Detects Acute Leptospirosis in Dogs with High Sensitivity and Specificity.

A rapid IgM-detection immunochromatographic test (WITNESS® Lepto, Zoetis) has recently become available to identify acute canine leptospirosis at the point of care. Diagnostic sensitivity and specificity of the test were evaluated by comparison with the microscopic agglutination assay (MAT), using a positive cut-off titer of ≥800. Banked serum samples from dogs exhibiting clinical signs and suspected leptospirosis were selected to form three groups based on MAT titer: (1) positive (n = 50); (2) borderline (n = 35); and (3) negative (n = 50). Using an analysis to weight group sizes to reflect French prevalence, the sensitivity and specificity were 98% and 93.5% (88.2% unweighted), respectively. This test rapidly identifies cases of acute canine leptospirosis with high levels of sensitivity and specificity with no interference from previous vaccination.

Patterns in Leptospira Shedding in Norway Rats (Rattus norvegicus) from Brazilian Slum Communities at High Risk of Disease Transmission.

BackgroundWe address some critical but unknown parameters of individuals and populations of Norway rats (Rattus norvegicus) that influence leptospiral infection, maintenance and spirochetal loads shed in urine, which contaminates the environment ultimately leading to human infection.Methodology/Principal FindingsOur study, conducted in Salvador, Brazil, established the average load of leptospires in positive kidneys to be 5.9 x 106 per mL (range 3.1-8.2 x106) genome equivalents (GEq), similar to the 6.1 x 106 per ml (range 2.2-9.4 x106) average obtained from paired urines, with a significant positive correlation (R2=0.78) between the two. Based on bivariate and multivariate modeling, we found with both kidney and urine samples that leptospiral loads increased with the age of rats (based on the index of body length to mass), MAT titer and the presence of wounding/scars, and varied with site of capture. Some associations were modified by sex but trends were apparent. Combining with data on the demographic properties and prevalence of leptospiral carriage in rat populations in Salvador, we estimated that daily leptospiral loads shed in the urine of a population of 82 individuals exceeded 9.1 x 1010 leptospires.Conclusions/SignificanceThese factors directly influence the risk of leptospiral acquisition among humans and provide essential epidemiological information linking properties of rat populations with risk of human infection.

Prevalence of infection with Toxoplasma gondii in landrace and mixed breed pigs slaughtered in Baja California Sur State, Mexico.

We performed a cross-sectional study to determine the seroprevalence of Toxoplasma gondii infection in 308 domestic pigs slaughtered in La Paz, Baja California Sur State, Mexico using the modified agglutination test (MAT, cut off 1:25). Forty (13%) of the 308 pigs were seropositive with MAT titers of 1:25 in 16, 1:50 in 5, 1:100 in 4, 1:200 in 5, 1:400 in 3, 1:800 in 3, 1:1600 in 2, and 1:3200 in 2. Multivariate analysis of pigs' characteristics showed that seropositivity to T. gondii was negatively associated with mixed breed (OR = 0.02; 95% CI: 0.003-0.26; P = 0.001). Other variables including sex, type of raising, and municipality did not show an association with T. gondii seropositivity by multivariate analysis. The frequency of high antibody titers (≥1:400) was significantly higher (P < 0.001) in Landrace pigs than mixed breed pigs. The seroprevalence of T. gondii infection in pigs for slaughter in Baja California Sur State is low compared with seroprevalences reported in pigs in other Mexican states. Landrace pigs demonstrated higher seroprevalence rates and antibody levels than mixed breed pigs. This is the first report of T. gondii infection in pigs raised in a desert climate.

Seroprevalence and seroincidence of Leptospira infection in dogs during a one-year period in an endemic urban area in Southern Brazil.

Leptospirosis is a zoonosis that affects both humans and animals. Dogs may serve as sentinels and indicators of environmental contamination as well as potential carriers for Leptospira. This study aimed to evaluate the seroprevalence and seroincidence of leptospirosis infection in dogs in an urban low-income community in southern Brazil where human leptospirosis is endemic. A prospective cohort study was designed that consisted of sampling at recruitment and four consecutive trimestral follow-up sampling trials. All households in the area were visited, and those that owned dogs were invited to participate in the study. The seroprevalence (MAT titers ≥100) of Leptospira infection in dogs was calculated for each visit, the seroincidence (seroconversion or four-fold increase in serogroup-specific MAT titer) density rate was calculated for each follow-up, and a global seroincidence density rate was calculated for the overall period. A total of 378 dogs and 902.7 dog-trimesters were recruited and followed, respectively. The seroprevalence of infection ranged from 9.3% (95% CI; 6.7 - 12.6) to 19% (14.1 - 25.2), the seroincidence density rate of infection ranged from 6% (3.3 - 10.6) to 15.3% (10.8 - 21.2), and the global seroincidence density rate of infection was 11% (9.1 - 13.2) per dog-trimester. Canicola and Icterohaemorraghiae were the most frequent incident serogroups observed in all follow-ups. Follow-ups with mean trimester intervals were incapable of detecting any increase in seroprevalence due to seroincident cases of canine leptospirosis, suggesting that antibody titers may fall within three months. Further studies on incident infections, disease burden or risk factors for incident Leptospira cases should take into account the detectable lifespan of the antibody.

Seroprevalence of Toxoplasma gondii infection in water buffaloes (Bubalus bubalis) in Veracruz State, Mexico and its association with climatic factors.

BackgroundInfection with Toxoplasma gondii in water buffaloes (Bubalus bubalis) is of epidemiological importance because of the risk for transmission to humans. We sought to determine the seroprevalence of T. gondii infection in 339 water buffaloes in Veracruz State, Mexico using the modified agglutination test (MAT, cut off 1:25). Seroprevalence association with general characteristics of buffaloes and their environment was also investigated.ResultsAntibodies to T. gondii were found in 165 (48.7%) of the 339 buffaloes with MAT titers of 1:25 in 104, 1:50 in 52, and 1:100 in 9. Bivariate analysis showed that seroprevalence of T. gondii infection was similar in buffaloes regardless of their general characteristics i.e., age, sex, and breed. In contrast, the seroprevalence in buffaloes varied significantly with environmental characteristics including altitude, mean annual temperature, and mean annual rainfall of the municipalities studied. Multivariate analysis showed that T. gondii seropositivity in buffaloes was associated with a mean annual rainfall between 1266–1650 mm (OR = 1.84; 95% CI: 1.15-2.94; P = 0.01).ConclusionsResults indicate that environmental characteristics may influence the seroprevalence of T. gondii infection in buffaloes. This is the first report on the seroprevalence of T. gondii infection in buffaloes in Mexico. Further research is needed to assess the risk for infection in humans associated with the ingestion of raw or undercooked meat from buffaloes infected with T. gondii.

Isolation and genetic characterization of Toxoplasma gondii from alpaca (Vicugna pacos) and sheep (Ovis aries).

Alpacas are important to the economy of several countries. Little is known of Toxoplasma gondii infection in alpacas worldwide. In the present study, T. gondii was isolated and genetically characterized from alpacas for the first time. Alpacas (n = 16) and rams (n = 12) pastured on a farm in Virginia, USA, were examined at necropsy. Antibodies to T. gondii were determined by the modified agglutination test (MAT, 1:25) and found in 6 of 16 alpacas with titers of 1:100 (2 alpaca), 1:400 (2 alpacas), 1:800 (1 alpaca), and 1:1,600 (1 alpaca), and 5 of 12 rams in titers of 1:50 in one, 1:400 in one, 1:800 in one, 1:1,600 in one, and 1:3,200 in one. Tissues of all 16 alpacas were bioassayed in mice or in cats. Muscles (heart, skeletal muscle) of nine alpacas with MAT titers of 1:25 were fed to T. gondii-free cats; the cats did not shed oocysts. Viable T. gondii was isolated from tissues of two of six seropositive alpacas by bioassay in mice. Viable T. gondii was isolated from three of three seropositive sheep by bioassay in mice. Genotyping using cell-cultured tachyzoites revealed four genotypes, including one for ToxoDB PCR-RFLP genotype #2 (type III), one for genotype #3 (type II variant), one for genotype #170, and two for a new genotype designated as ToxoDB PCR-RFLP genotype #230. Thus, four of the five T. gondii isolates in the present study belonged to different genotypes. These results indicate a higher genetic diversity among T. gondii isolates circulating in the USA than previously realized.

Seroprevalence and correlates of Toxoplasma gondii infection in domestic pigs in Veracruz State, Mexico

Toxoplasma gondii infection in pigs has epidemiological concern for its contributing role in human infections. We determined seroprevalence of T. gondii infection in 402 domestic pigs raised in backyards in Veracruz State, Mexico using the modified agglutination test (MAT; cut off 1:25); 182 (45.3%) of the 402 pigs were seropositive with MAT titers of 1:25 in 28, 1:50 in 22, 1:100 in 18, 1:200 in 30, 1:400 in 35, 1:800 in 23, 1:1,600 in 11, and 1:3,200 or higher in 15. Seropositive pigs were found in 137 (53.3%) of 257 homes in all 7 municipalities surveyed. Multivariate analysis showed that T. gondii seropositivity in pigs was associated with tropical-humid climate (OR = 4.32; 95% CI 1.47-12.62; P = 0.007) of the raising municipalities, feeding with leftovers (OR = 2.83; 95% CI 1.01-7.91; P = 0.04), storing pig food in the owner's home (OR = 2.39; 95% CI 1.09-5.22; P = 0.02), and free ranging (OR = 3.48; 95% CI 1.49-8.15; P = 0.003). Results indicate that backyard pigs in Veracruz have the highest seroprevalence of T. gondii infection obtained by MAT in pigs studied in Mexico so far. The correlates of T. gondii infection found in the present study may be useful for an optimal planning of preventive measures against T. gondii infection in pigs. Results also remark the risk of T. gondii infection in humans by ingestion of raw or undercook pork in Mexico.