Reported are results of serologic examinations for the presence of anti-Toxoplasma antibodies by direct agglutination in 1,497 people: 1,327 forestry workers and 86 farmers occupationally exposed to T. gondii from the Lublin region (eastern Poland) and 84 inhabitants of the city of Lublin examined as the control group, including 50 blood donors and 34 workers from forestry headquarters. 58.5% positive results in forestry workers, 56.9% in farmers and 46.4% in the control group were obtained. The highest percentages of positive results were obtained in Sosnowica, Wlodawa and Sobibor, all localities in the Chelm district. This finding and the prevalence of clinical cases may suggest that the Chelm district (easternmost area of the Lublin region, bordering Ukraine) is an endemic area of toxoplasmosis. A case of toxoplasmosis in a 39 year old farmer is described in whom reinfection was identified 20 years after primary diagnosis. Rapid increase in specific serologic titres and symptoms typical for toxoplasmosis were noted. The rest of the family and household animals were also found to be positive which supports the suggestion of a family-environmental case of toxoplasmosis. Survey for anti-Toxoplasma antibodies in various domestic and wild animals comprised sera from 262 cows, 120 pigs, 34 geese, 65 chickens, 3 roe deer and 10 sheep from the Lublin region. High percentages of positive results were found in cattle (53.8%) and in pigs (15%). Fowl were positive only in 0-5.9%. The cattle and pigs from the Chelm district are most probably the main sources of toxoplasmosis threatening humans in this area.

BACKGROUND: Outbreaks of toxoplasmosis are recognised infrequently. In March, 1995, a sudden increase of serologically diagnosed cases of acute toxoplasmosis was noted in the Greater Victoria area of British Columbia, Canada. Concurrently, but independently, seven cases of acute toxoplasma retinitis were diagnosed against a background of no cases in the previous 5 years. METHODS: Cases were defined by serological testing, clinical presentation, and residence in Greater Victoria. A screening programme for women who were or had been pregnant was started. Geographical mapping of cases, and case-control studies of symptomatic cases and of women enrolled in the screening programme were done. FINDINGS: 100 individuals aged 6 to 83 years met the definition for an acute, outbreak-related case. 94 resided in Greater Victoria and six had visited it; 19 had retinitis, 51 had lymphadenopathy, four others had symptoms consistent with toxoplasmosis, seven had other symptoms, 18 were symptom-free, and one would not provide information. 36 (0.9%) of 3812 screened pregnant and postnatal women were cases. Excess cases were not detected outside Greater Victoria and no conventional source of toxoplasmosis was implicated. Mapping studies of cases and of the screened women, and both case-control studies showed significant associations between acute infection and residence in the distribution system of one reservoir supplying water to Greater Victoria (ORs or RRs: 3.53, 3.05, 8.27, and 5.42, respectively). The epidemic curve appeared bimodal, with peaks in December, 1994, and March, 1995, that were preceded by increased rainfall and turbidity in the implicated reservoir. INTERPRETATION: A municipal water system that uses unfiltered, chloraminated surface water was the likely source of this large community-wide outbreak of toxoplasmosis.

Classification systems and case definitions provide the foundations upon which clinical and epidemiological studies are based. The European Research Network on Congenital Toxoplasmosis acknowledged the lack of such a system or definitions within its field of interest and established a working group to address the issue. Congenital Toxoplasma gondii infection was defined as occurring in four separate patient groups: pregnant women, fetuses, infants, and individuals > 1 year of age. The likelihood of Toxoplasma gondii infection was separated into five mutually exclusive categories: definite, probable, possible, unlikely, and not infected. Inclusion within a specific category is dependent upon the case definition, which is in turn derived from criteria based on serological, parasitological, and clinical information. Notes are included within the classification not only to clarify the definitions, but also to improve the reliability and quality of diagnosis. The goal is to construct a system that encompasses all aspects of congenital toxoplasmosis, which is applicable to different countries and health services, suitable for large epidemiological studies, aids the diagnosis and management of individual cases, and lends itself to computerisation.

Primary infection with Toxoplasma gondii, a parasite found in most regions of the world, is asymptomatic in more than 80% of cases. However, primary infection with Toxoplasma gondii in a pregnant woman might cause fetal infection and severe damage. Most cases do not require treatment. This applies to women without any infection (denoted as seronegative) and women who have acquired the infection before conception (denoted as latent). In contrast, women with postconceptual infection require immediate treatment to prevent or ameliorate fetal infection. We have developed an expert system, called Toxoport-I, designed for routine laboratory work, which automatically interprets serological test results of toxoplasma infection. By using the system the clinician can also examine questionable cases by interactively exploring possible results. We used a popular method of designing expert systems applied to medical interpretation and therapy advice, the rule-based one. In order to meet the requirements of automatic interpretation in toxoplasma serology the following characteristics were introduced: the interpretation of sequences of test results, the possibility of excluding inconsistent test results and the adaptability of the knowledge base. A decision graph that covers the different kinds of infections as well as therapy and recommendations for further tests was designed, implemented and was clinically tested by carrying out a retrospective study including 1000 pregnant women. A comparison of Toxoport-I and the clinician's interpretations yielded sensitivity and specificity rates of over 99% each.

Toxoplasmosis encompasses a variety of clinical conditions. Serious sequelae are seen in congenital toxoplasmosis and in infections of the immunocompromised host. In the former, prevention of maternal acquisition of toxoplasmosis during pregnancy is paramount. Infection in the compromised host often presents with neurologic abnormalities. Unfortunately, the HIV syndrome itself or other opportunistic infections can present in a similar manner. Often, empiric treatment for toxoplasmosis is begun based on clinical findings and an enhancing lesion noted on the head CT. Pyrimethamine and sulfadiazine remain the drugs of choice for toxoplasmosis and are able to penetrate blood-brain barriers. Currently, trials using other agents are in progress.