Low prevalence of viable Toxoplasma gondii in fresh, unfrozen American pasture-raised pork and lamb from retail meat stores in the United States.

In a national survey of fresh, unfrozen, American pasture-raised lamb and pork, the prevalence of viable Toxoplasma gondii was determined in 1500 samples selected by random multistage sampling (750 pork, 750 lamb) obtained from 250 retail meat stores from 10 major geographic areas in the USA. Each sample consisted of a minimum of 500g of meat purchased from the retail meat case. To detect viable T. gondii, 50g meat samples of each of 1500 samples were bioassayed in mice. Viable T. gondii was isolated from 2 of 750 lamb samples (unweighted: 0.19%, 0.00-0.46%; weighted: 0.04%, 0.00-0.11%) and 1 of 750 pork samples (unweighted: 0.12%, 0.00-0.37%; weighted: 0.18%, 0.00-0.53%) samples. Overall, the prevalence of viable T. gondii in these retail meats was very low. Nevertheless, consumers, especially pregnant women, should be aware that they can acquire T. gondii infection from ingestion of undercooked meat. Cooking meat to an internal temperature of 66°C kills T. gondii.

Survey of Obstetrician-gynecologists in the United States About Trichomoniasis, 2016.

PURPOSE: Trichomoniasis is the most prevalent nonviral sexually transmitted infection (STI) in the United States. It can present with vaginitis in women and urethritis in men, but is most often asymptomatic or occurs with minimal symptoms. It is associated with other STIs, adverse pregnancy outcomes and pelvic inflammatory disease. For these reasons, health care provider awareness of trichomoniasis is of public health importance. METHODS: To assess practitioner knowledge, attitudes, and practices concerning trichomoniasis management, the American College of Obstetricians and Gynecologists conducted an online survey in 2016 of its members, and we analyzed results from 230 respondents. RESULTS: We note discrepancies between practice and recommendations among surveyed providers: a minority of respondents routinely screen human immunodeficiency virus (HIV)-positive patients for trichomoniasis (10.7%, "most of the time"; 95% confidence interval [CI], 6.7-15.8; 33.0%, "always"; 95% CI, 26.5%-40.0%), treat trichomoniasis in HIV-positive patients with the recommended dose of metronidazole 500 mg twice a day for 7 days (25.8%; 95% CI, 20.0%-32.3%), or retest patients diagnosed with trichomoniasis 3 months after treatment (9.6%; 95% CI, 6.1%-14.3%). Only 29.0% (95% CI, 23.0%-35.5%) retreat with metronidazole 500 mg twice a day for 7 days in patients who have failed prior treatment. CONCLUSIONS: Screening for and treatment of trichomoniasis in HIV-positive patients, and retesting and retreatment for trichomoniasis in the general population appear to be suboptimal. Continuing education for providers is needed for this common but "neglected" STI.

Seroprevalence of Antibodies to Toxocara Species in the United States and Associated Risk Factors, 2011-2014.

Background: Toxocariasis results from infection with larval stages of a dog and cat intestinal nematode and causes human morbidity. The current United States estimate of Toxocara exposure is 13.9% (National Health and Nutrition Examination Survey [NHANES] III [1988-1994]). Methods: We used a multiplex bead-based assay (Tc-CTL-1MBA) with purified Toxocara canis antigen to estimate Toxocara antibody seroprevalence in serum of 13 509 persons aged ≥6 years from NHANES 2011-2014 and identified seropositivity risk factors. We tested a subset of 500 samples with the T. canis enzyme immunoassay used in NHANES III to estimate prior seroprevalence had samples from NHANES III been tested by Tc-CTL-1MBA. Results: The age-standardized estimate of Toxocara seroprevalence was 5.0% (95% confidence interval [CI], 4.2%-5.8%), lower than previously reported even after adjusting for increased Tc-CTL-1MBA specificity. Risk factors for seropositivity from multiple logistic regression were older age, non-Hispanic black/Hispanic origin, male sex, living below poverty level, households with ≥0.5 persons per room, less than college education, and birth outside of the United States. Conclusions: Toxocara seroprevalence estimates in 2011-2014 were lower than in a study from NHANES III (1988-1994), but seropositivity risk factors remained the same and should continue to be the focus of prevention efforts.

No evidence for airborne transmission of Toxoplasma gondii in a very high prevalence area in Lancaster County.

BACKGROUND: Toxoplasma gondii (T. gondii) has been associated with acute food-borne illness, chronic low-grade inflammation, neuropsychiatric conditions and reactivation of chronic latent infection in immunocompetent hosts. Primary infection with T. gondii in pregnant women can lead to congenital toxoplasmosis. In addition to well-known oral tissue-cyst or oocyst ingestion, we hypothesized that the very high prevalence of T. gondii in certain populations exposed to agricultural dust could be, in part, a consequence of airborne infection with oocysts. METHODS: Wo collected environmental dust samples from an area with a reportedly high T. gondii seroprevalence in the Old Order Amish population, in Lancaster, Pennsylvania. Samples included: a) air filters from air-conditioning units; b) swabs of settled dust; and c) vacuum filters containing airborne field dust. Pools of the swabs and shredded sub-samples of the air filters were fed to pigs, with inoculation into mice of heart tissue from seroconverted pigs. We also investigated the presence of T. gondii DNA using PCR amplification. RESULTS: Only one pig seroconverted. However, bioassay of pig heart tissue further inoculated into mice showed no evidence of T. gondii infection. Consistently, no evidence of T. gondii DNA was revealed in any sample. CONCLUSIONS: No evidence of airborne transmission was found in the environmental samples that were examined.

Development of Dose-Response Models to Predict the Relationship for Human Toxoplasma gondii Infection Associated with Meat Consumption.

Toxoplasma gondii is a protozoan parasite that is responsible for approximately 24% of deaths attributed to foodborne pathogens in the United States. It is thought that a substantial portion of human T. gondii infections is acquired through the consumption of meats. The dose-response relationship for human exposures to T. gondii-infected meat is unknown because no human data are available. The goal of this study was to develop and validate dose-response models based on animal studies, and to compute scaling factors so that animal-derived models can predict T. gondii infection in humans. Relevant studies in literature were collected and appropriate studies were selected based on animal species, stage, genotype of T. gondii, and route of infection. Data were pooled and fitted to four sigmoidal-shaped mathematical models, and model parameters were estimated using maximum likelihood estimation. Data from a mouse study were selected to develop the dose-response relationship. Exponential and beta-Poisson models, which predicted similar responses, were selected as reasonable dose-response models based on their simplicity, biological plausibility, and goodness fit. A confidence interval of the parameter was determined by constructing 10,000 bootstrap samples. Scaling factors were computed by matching the predicted infection cases with the epidemiological data. Mouse-derived models were validated against data for the dose-infection relationship in rats. A human dose-response model was developed as P (d) = 1-exp (-0.0015 × 0.005 × d) or P (d) = 1-(1 + d × 0.003 / 582.414)(-1.479) . Both models predict the human response after consuming T. gondii-infected meats, and provide an enhanced risk characterization in a quantitative microbial risk assessment model for this pathogen.

A Systematic Meta-Analysis of Toxoplasma gondii Prevalence in Food Animals in the United States.

Toxoplasma gondii is a widely distributed protozoan parasite. The Centers for Disease Control and Prevention reported that T. gondii is one of three pathogens (along with Salmonella and Listeria), that together account for >70% of all deaths due to foodborne illness in the United States. Food animals are reservoirs for T. gondii and act as one of the sources for parasite transmission to humans. Based on limited population-based data, the Food and Agriculture Organization/World Health Organization estimated that approximately 22% of human T. gondii infections are meatborne. The objective of the current study was to conduct a systematic meta-analysis to provide a precise estimation of T. gondii infection prevalence in food animals produced in the United States. Four databases were searched to collect eligible studies. Prevalence was estimated in six animal categories (confinement-raised market pigs, confinement-raised sows, non-confinement-raised pigs, lamb, goats, and non-confinement-raised chickens) by a quality-effects model. A wide variation in prevalence was observed in each animal category. Animals raised outdoors or that have outdoor access had a higher prevalence as compared with animals raised indoors. T. gondii prevalence in non-confinement-raised pigs ranked the highest (31.0%) followed by goats (30.7%), non-confinement-raised chickens (24.1%), lambs (22.0%), confinement-raised sows (16.7%), and confinement-raised market pigs (5.6%). These results indicate that T. gondii-infected animals are a food safety concern. The computed prevalence can be used as an important input in quantitative microbial risk assessment models to further predict public health burden.

Ocular toxoplasmosis in the United States: recent and remote infections.

We tested all samples from patients with ocular toxoplasmosis sent to the Palo Alto Medical Foundation Toxoplasma Reference Laboratory from June 2004 through August 2010 for serologic evidence of recent Toxoplasma gondii infection. Of 205 patients aged 10-96 years, 11.7% had recent infection. Many people develop ocular disease soon after T. gondii infection.

Survey of obstetrician-gynecologists in the United States about toxoplasmosis: 2012 update.

PURPOSE: Toxoplasmosis, caused by the parasite Toxoplasma gondii, can have serious impacts on fetal development in the setting of acute maternal primary infection. The American College of Obstetricians and Gynecologists (ACOG) sought to determine current knowledge, practices, opinions, and educational preferences regarding T. gondii infection in pregnancy among ACOG members practicing prenatal care. METHODS: ACOG sent a survey to 1,056 members chosen by stratified random sampling from membership lists, including 370 participants and 686 non-participants in the Collaborative Ambulatory Research Network (CARN). Mailings were sent up to four times to nonresponders. RESULTS: Survey minimum response rates were 40.3% (CARN) and 19.7% (non-CARN); response rates adjusted for imputed non-eligibility were 59.7% (CARN) and 22.6% (non-CARN). Among providers, 80.2% had diagnosed no acute maternal T. gondii infections in the past 5 years, 12.7% correctly identified the screening role of the Toxoplasma avidity test, 42.6% performed serologic T. gondii screening for at least some asymptomatic pregnant women, and 62.1% of those who so did used appropriate approaches. Providers in the northeastern United States were 2.02 times more likely to routinely screen than those in the west (p = 0.025) and female providers were 1.48 times more likely than male providers (p = 0.047). The potential educational interventions considered useful by the most practitioners were updated ACOG guidelines on screening (81.4%) and management (71.7%) for acute T. gondii infection in pregnancy. CONCLUSIONS: ACOG members would benefit from educational efforts targeted at risk factor counseling and screening approaches.

The association of Toxoplasma gondii infection with neurocognitive deficits in a population-based analysis.

PURPOSE: To examine the relationship between infection with Toxoplasma gondii (toxo) and cognition. METHODS: Multivariate logistic regression was used to test the association of toxo seropositivity with indices of cognitive function among over 4,200 adults in the third National Health and Nutrition Examination Survey. RESULTS: Toxo-seropositive participants were more likely than seronegative participants to score in the worst quartile of the simple reaction time test (OR 1.3, 95 % CI 1.0, 1.6), symbol-digit substitution test (SDST, OR 1.5, 95 % CI 1.2, 1.9) and the serial-digit learning test (trials to criterion) (SDLTNT, OR 1.4, 95 % CI 1.1, 1.8) in models adjusted for age, race/ethnicity, gender and foreign birth. After further adjustment for all cofactors, the association between toxo seropositivity and these outcomes was no longer significant. However, seropositivity was associated with worse scores on the SDST (OR 2.9, 95 % CI 1.8, 4.8) among those in the lowest income category and the SDLTNT (OR 1.5, 95 % CI 1.1, 2.5) among those foreign born. CONCLUSIONS: Toxo seropositivity may be associated with poor cognitive test scores in certain subgroups; however, causation cannot be established in this cross-sectional study.

Neglected parasitic infections: what every family physician needs to know.

Neglected parasitic infections, including Chagas disease, toxocariasis, cysticercosis, and toxoplasmosis, affect millions of persons in the United States. Relatively few resources have been devoted to surveillance, prevention, and treatment of these diseases. Chagas disease primarily affects Latin American immigrants and can cause heart failure and death if not treated. Immediate antiparasitic treatment is indicated for most patients with acute Chagas disease. Treatment is recommended for patients younger than 18 years who have chronic Chagas disease and is generally recommended for adults younger than 50 years who do not have advanced cardiomyopathy; treatment decisions for other patients should be made on an individual basis. Toxocariasis primarily affects children and can cause gastrointestinal, respiratory, and ophthalmologic disease. Treatment options include albendazole and mebendazole. Patients with ocular infection require referral to an ophthalmologist. Neurocysticercosis, a form of cysticercosis, is the most common infectious cause of seizures in some parts of the United States. Initial treatment should focus on symptom control. Humans generally acquire toxoplasmosis by eating undercooked contaminated meat or ingesting things that have been contaminated with cat feces. Congenital infection can result in miscarriage or adverse fetal effects. Treatment is recommended for immunosuppressed persons, pregnant women, and immunocompetent persons with severe symptoms.

A pilot study using residual newborn dried blood spots to assess the potential role of cytomegalovirus and Toxoplasma gondii in the etiology of congenital hydrocephalus.

BACKGROUND: Congenital hydrocephalus is a condition characterized by accumulation of cerebrospinal fluid in the ventricles of the brain. Prenatal infections are risk factors for some birth defects. This pilot study investigated whether residual dried blood spots (DBS) could be used to assess infections as risk factors for birth defects by examining the associations between prenatal infection with Toxoplasma gondii (T. gondii) or cytomegalovirus (CMV) with congenital hydrocephalus. METHODS: Case-infants with hydrocephalus (N=410) were identified among live-born infants using birth defects surveillance systems in California, North Carolina, and Texas. Control-infants without birth defects were randomly selected from the same geographic areas and time periods as case-infants (N=448). We tested residual DBS from case- and control-infants for T. gondii immunoglobulin M and CMV DNA. When possible, we calculated crude odds ratios (cORs) and confidence intervals (CIs). RESULTS: Evidence for prenatal T. gondii infection was more common among case-infants (1.2%) than control-infants (0%; p=0.11), and evidence for prenatal CMV infection was higher among case-infants (1.5%) than control-infants (0.7%; cOR: 2.3; 95% CI: 0.48, 13.99). CONCLUSIONS: Prenatal infections with T. gondii and CMV occurred more often among infants with congenital hydrocephalus than control-infants, although differences were not statistically significant. This pilot study highlighted some challenges in using DBS to examine associations between certain infections and birth defects, particularly related to reduced sensitivity and specimen storage conditions. Further study with increased numbers of specimens and higher quality specimens should be considered to understand better the contribution of these infections to the occurrence of congenital hydrocephalus.

Toxoplasmosis hospitalizations in the United States, 2008, and trends, 1993-2008.

BACKGROUND: Toxoplasmosis-related hospitalizations often occur in persons with human immunodeficiency virus (HIV) infection and other causes of immunosuppression. METHODS: Using the National Inpatient Sample (NIS) from the Healthcare Cost and Utilization Project, we examined trends in toxoplasmosis-related hospitalizations by HIV infection status from 1993 through 2008, and rates by sex and race or ethnicity in 2008. The NIS is designed to represent a 20% sample of US community hospitals and currently includes information on up to 8 million discharges per year from ∼1000 hospitals. We used International Classification of Diseases, Ninth Revision, Clinical Modification codes 130-130.9 for toxoplasmosis and 042-044/795.8/795.71/V08 for HIV infection. RESULTS: Estimated HIV-associated toxoplasmosis hospitalizations increased from 9395 in 1993 to 10583 in 1995 (P = .0002), then dropped to 3643 in 2001 (P < .0001), with similar levels thereafter. The rate of HIV-associated toxoplasmosis hospitalizations among all HIV-related hospitalizations decreased from 3.33% in 1993 to 1.25% in 2008 (P < .0001). Estimated non-HIV-associated toxoplasmosis hospitalizations were less variable from 1993 to 2008 (range, 386-819; 0.0020% in 1993, 0.0015% in 2008). In 2008, the rates of both HIV- and non-HIV-associated toxoplasmosis hospitalizations were higher in Hispanic persons than in white persons. CONCLUSIONS: HIV-associated toxoplasmosis hospitalizations dropped markedly after 1995 when highly active antiretroviral therapy was introduced; however, hospitalizations decreased relatively little after 2000, suggesting late diagnosis of some HIV-infected persons or antiretroviral therapy failure. Non-HIV-associated toxoplasmosis hospitalizations have been more stable. The rates of toxoplasmosis-related hospitalizations varied markedly among racial and ethnic groups.

Foodborne toxoplasmosis.

Toxoplasmosis can be due to congenital infection or acquired infection after birth and is one of the leading illnesses associated with foodborne hospitalizations and deaths. Undercooked meat, especially pork, lamb, and wild game meat, and soil contaminated with cat feces on raw fruits and vegetables are the major sources of foodborne transmission for humans. The new trend in the production of free-range organically raised meat could increase the risk of Toxoplasma gondii contamination of meat. Foodborne transmission can be prevented by production practices that reduce T. gondii in meat, adequate cooking of meat, washing of raw fruits and vegetables, prevention of cross contamination in the kitchen, and measures that decrease spread of viable oocysts into the environment.

Population-based active surveillance for Cyclospora infection--United States, Foodborne Diseases Active Surveillance Network (FoodNet), 1997-2009.

BACKGROUND: Cyclosporiasis is an enteric disease caused by the parasite Cyclospora cayetanensis. Since the mid-1990 s, the Centers for Disease Control and Prevention has been notified of cases through various reporting and surveillance mechanisms. METHODS: We summarized data regarding laboratory-confirmed cases of Cyclospora infection reported during 1997-2009 via the Foodborne Diseases Active Surveillance Network (FoodNet), which gradually expanded to include 10 sites (Connecticut, Georgia, Maryland, Minnesota, New Mexico, Oregon, Tennessee, and selected counties in California, Colorado, and New York) that represent approximately 15% of the US population. Since 2004, the number of sites has remained constant and data on the international travel history and outbreak status of cases have been collected. RESULTS: A total of 370 cases were reported, 70.3% (260) of which were in residents of Connecticut (134 [36.2%]) and Georgia (126 [34.1%]), which on average during this 13-year period accounted for 29.0% of the total FoodNet population under surveillance. Positive stool specimens were collected in all months of the year, with a peak in June and July (208 cases [56.2%]). Approximately half (48.6%) of the 185 cases reported during 2004-2009 were associated with international travel, known outbreaks, or both. CONCLUSIONS: The reported cases were concentrated in time (spring and summer) and place (2 of 10 sites). The extent to which the geographic concentration reflects higher rates of testing, more sensitive testing methods, or higher exposure/infection rates is unknown. Clinicians should include Cyclospora infection in the differential diagnosis of prolonged or relapsing diarrheal illness and explicitly request stool examinations for this parasite.

Ocular toxocariasis: epidemiologic, anatomic, and therapeutic variations based on a survey of ophthalmic subspecialists.

PURPOSE: To assess the current burden of ocular toxocariasis (OT) and to gain knowledge regarding the diagnostic and treatment practices used in the ophthalmologic community in the United States. DESIGN: Web-based, cross-sectional survey. PARTICIPANTS: Subspecialty ophthalmologists who are currently practicing in the United States. METHODS: An electronic survey was sent to 3020 ophthalmologic subspecialists belonging to the American Uveitis Society (AUS), the American Society of Retina Specialists (ASRS), or the American Association for Pediatric Ophthalmology and Strabismus (AAPOS) to capture demographic, clinical, diagnostic, and treatment data on patients with OT seen in their practices between September 2009 and September 2010. MAIN OUTCOME MEASURES: The demographic, epidemiologic, and clinical characteristics of each reported patient with OT. RESULTS: A total of 159 patients with OT were reported by 559 respondents (19%). The median patient age was 11.5 years (range, 1-66 years). Seventy-two patients (45%) with OT lived in the Southern region of the United States. Thirty-one (69%) of 45 patients with OT owned a dog or cat. Vision loss was reported in 46 (85%) of 54 patients with OT; 32 (71%) of 45 patients had permanent vision loss, 13 patients (29%) had temporary vision loss, and duration of vision loss was unreported for 1 patient. Of the 32 patients with OT with permanent vision loss, 30 (94%) had a subretinal granulomatous mass/scar, peripheral granuloma with traction bands, or posterior pole granuloma noted on ophthalmologic examination. Subretinal granulomatous mass/scar, vitritis, and scotoma were the most common ophthalmologic signs found on examination of patients with OT. CONCLUSIONS: Ocular toxocariasis continues to occur in the United States, where it affects mainly children and causes permanent vision loss in many patients. Healthcare professionals should counsel patients and their family members about prevention strategies in an effort to decrease infection rates and morbidity due to Toxocara. Further improvement of diagnostic and treatment tools is needed to assist ophthalmologists in treating patients with OT. FINANCIAL DISCLOSURE(S): The author(s) have no proprietary or commercial interest in any materials discussed in this article.

First provincial survey of Angiostrongylus cantonensis in Guangdong Province, China.

The rat lungworm Angiostrongylus cantonensis is a zoonotic nematode with a wide distribution. We report the first provincial survey of the prevalence of A. cantonensis infection among wild rodents and snails in Guangdong Province, China. A total of 2929 Pomacea canaliculata and 1354 Achatina fulica were collected from fields in 22 survey sites with a larval infection rates ranging from 0-26.6% to 0-45.4%. In addition, 114 Cipangopaludina sp and 252 Bellamya sp were bought from markets; larvae were found only in Bellamya snails from two survey sites with an infection rate of 1.4% (1/70) and 3.3% (3/91), respectively. Four hundred and ninety-one rodents were captured in nine sites (Rattus norvegicus, R. flavipectus, Suncus murinus, Mus musculus, Bandicota indica, R. losea and R. rattus). Adult worms were found in R. norvegicus, R. flavipectus and Bandicota indica. Our survey revealed a wide distribution of A. cantonensis and its intermediate hosts P. canaliculata and A. fulica in Guangdong. The prevalence of A. cantonensis in wild snails and rats poses a substantial risk for angiostrongyliasis in humans.

Identification of an atypical strain of toxoplasma gondii as the cause of a waterborne outbreak of toxoplasmosis in Santa Isabel do Ivai, Brazil.

Multilocus DNA sequencing has identified a nonarchetypal strain of Toxoplasma gondii as the causal agent of a waterborne outbreak in Brazil in 2001. The strain, isolated from a water supply epidemiologically linked to the outbreak, was virulent to mice, and it has previously been identified as BrI. Using a serologic assay that detects strain-specific antibodies, we found that 13 (65%) of 20 individuals who were immunoglobulin (Ig) M positive during the outbreak possessed the same serotype as mice infected with the purported epidemic strain. The remaining 7 individuals, plus additional IgM-negative, IgG-positive individuals, possessed 1 of 4 novel serotypes, the most common of which matched the serotype of mice infected with strains isolated from chickens foraging near the outbreak site. The latter strains likely reflect the genetic diversity of T. gondii circulating in highly endemic regions of Brazil. The serotyping assay proved a useful tool for identification of specific individuals infected with the outbreak agent.

Risk factors for Toxoplasma gondii infection in the United States.

BACKGROUND: Toxoplasmosis can cause severe ocular and neurological disease. We sought to determine risk factors for Toxoplasma gondii infection in the United States. METHODS: We conducted a case-control study of adults recently infected with T. gondii. Case patients were selected from the Palo Alto Medical Foundation Toxoplasma Serology Laboratory from August 2002 through May 2007; control patients were randomly selected from among T. gondii-seronegative persons. Data were obtained from serological testing and patient questionnaires. RESULTS: We evaluated 148 case patients with recent T. gondii infection and 413 control patients. In multivariate analysis, an elevated risk of recent T. gondii infection was associated with the following factors: eating raw ground beef (adjusted odds ratio [aOR], 6.67; 95% confidence limits [CLs], 2.09, 21.24; attributable risk [AR], 7%); eating rare lamb (aOR, 8.39; 95% CLs, 3.68, 19.16; AR, 20%); eating locally produced cured, dried, or smoked meat (aOR, 1.97; 95% CLs, 1.18, 3.28; AR, 22%); working with meat (aOR, 3.15; 95% CLs, 1.09, 9.10; AR, 5%); drinking unpasteurized goat's milk (aOR, 5.09; 95% CLs, 1.45, 17.80; AR, 4%); and having 3 or more kittens (aOR, 27.89; 95% CLs, 5.72, 135.86; AR, 10%). Eating raw oysters, clams, or mussels (aOR, 2.22; 95% CLs, 1.07, 4.61; AR, 16%) was significant in a separate model among persons asked this question. Subgroup results are also provided for women and for pregnant women. CONCLUSIONS: In the United States, exposure to certain raw or undercooked foods and exposure to kittens are risk factors for T. gondii infection. Knowledge of these risk factors will help to target prevention efforts.