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A seroepizootiological study of Toxoplasma gondii infection involving a total of 488 slaughter pigs (468 market-weight pigs and 20 sows) in the Belgrade area, also included examination of the presence of T. gondii in the blood. Blood sampled at the slaughter line was examined for specific antibodies by modified direct agglutination, and blood clots of those seropositive at titres of 1:50-1:12800 were bioassayed in mice. The overall seroprevalence was 9.2%, significantly higher (p = 0.0063) in sows (30.0%) than in market-weight pigs (8.3%). Amongst the 22 bioassays performed, a total of 16 (72.7%) were positive, by observation of T. gondii cysts (12), seropositivity (7, including 3 in which cysts were not detected), and/or detection of T. gondii DNA by real-time PCR (12, including one otherwise negative). The positive bioassays originated from the blood of 12 market-weight pigs and 4 sows. Despite a general increase in the rate of demonstration of T. gondii with the increase in the specific antibody level, the association was not significant (p = 0.101). The risk of infection was 41-fold increased in sows vs market-weight pigs, and 15-fold in pigs from smallholders' finishing type farms vs those from large farrow-to-finish farms. The presence of viable T. gondii in a proportion of the samples indicates that some of the pigs had an active parasitaemia at the time of slaughter, which, along with the seroprevalence established, points to a potential source of human infection in Serbia. This is the first report on parasitaemia in naturally infected swine.

Determination of the avidity of specific IgG antibodies has become a generally accepted diagnostic aid for dating Toxoplasma infection. In this study, the Labsystems, VIDAS and EUROIMMUN Toxoplasma IgG avidity assays were compared on a series of 133 Toxoplasma IgG-and IgM-positive sera from symptomatic patients (n528), from pregnant (n543) and nonpregnant (n526) women, and on 18 IgG-positive and IgM-negative sera from chronically infected patients. The results showed excellent concordance between the Labsystems and VIDAS tests in both the IgM-positive (r50.82, k50.771) and IgM-negative (k50.609) sera, whilst the agreement of the EUROIMMUN assay with both the Labsystems and VIDAS tests in the IgM-positive sera was moderate (k50.575 and k50.525, respectively) and in the IgM-negative sera was poor (k50.000). Analysis of the kinetics of the maturation of avidity in 13 patients in whom follow-up sera were available showed that, despite a general trend of maturation, in two patients the avidity did not become high during 6 and 11 months of follow-up. In view of the clinical setting, in the symptomatic patients, despite one case of complete discrepancy and five cases of partial discrepancy, the Labsystems and VIDAS tests were in almost perfect agreement (k50.812), whilst the agreement in pregnant and non-pregnant women was substantial (k50.754 and k50.708, respectively). In conclusion, the Labsystems and VIDAS tests are equally reliable for the measurement of Toxoplasma IgG avidity; the choice of test should depend on the laboratory setup. The EUROIMMUN test may be an acceptable alternative in resource-limited settings, but should be used prudently.

To assess the role of synanthropic rodents in the epidemiology of urban toxoplasmosis, Toxoplasma gondii infection was examined in 144 rats (Rattus norvegicus) and 12 mice (Mus musculus) captured using live animal traps in three locations in Belgrade city characterized by poor housing and degraded environment. In rats, specific IgG antibodies were detected by modified agglutination test in 22 (27.5%) of the 80 blood samples available. Toxoplasma brain cysts were microscopically detected in 11 (7.6%), and Toxoplasma DNA by real-time polymerase chain reaction was demonstrated in 15 (10.4%) animals. Of these, both cysts and Toxoplasma DNA were detected in five (3.5%) rats. In mice, cysts were observed in 3 (25%), but Toxoplasma DNA was detected in even 10 (83.3%) animals, including all 3 with morphologically recognized cysts. Being a link in the chain of Toxoplasma infection, the existence of urban rodent reservoirs of infection represents a public health risk.

Seasonality patterns should be taken into account in the health education guidelines for the prevention of toxoplasmosis in pregnant women.

Despite the public health importance of giardiasis in all of Europe, reliable data on the incidence and prevalence in Western Balkan Countries (Serbia, Bosnia and Herzegovina, Croatia, Montenegro and FYR Macedonia) are scarce, and the relative contribution of waterborne and food-borne, or person-to-person and/or animalto- person, transmission of human giardiasis is not yet clear. To provide baseline data for the estimation of the public health risk caused by Giardia, we here review the information available on the epidemiological characteristics of asymptomatic and symptomatic human infection in Serbia. Although asymptomatic cases of Giardia represent a major proportion of the total cases of infection, high rates of Giardia infection were found in both asymptomatic and symptomatic populations. No waterborne outbreaks of giardiasis have been reported, and it thus seems that giardiasis mostly occurs sporadically in our milieu. Under such circumstances, control measures to reduce the high prevalence of giardiasis in Serbia have focused on person-to-person transmission, encouraging proper hygiene, but for more targeted intervention measures, studies to identify other risk factors for asymptomatic and symptomatic infections are needed.

Host lipids have been implicated in the pathogenesis of Toxoplasma gondii infection. To determine if Key words: toxoplasmosis -murine infection -lipid metabolism -cholesterol -adiponectinThere is an emerging body of evidence showing that the intracellular protozoan Toxoplasma gondii alters host cell metabolism for entry and replication and uses host metabolic products for its own metabolic pathways. Toxoplasma cannot synthesize cholesterol (Chl) de novo and depends upon acquisition of low density lipoprotein (LDL)-derived Chl from the host cell, via endocytosis mediated by the LDL receptor (Coppens et al. 2000) or the LDL receptor-related protein (Portugal et al. 2008). A mechanism by which host and not parasite Chl controls the entry of Toxoplasma into cells has been proposed (Coppens & Joiner 2003). These studies indicate that Chl does have an important role in pathogenesis of toxoplasmosis. However, data on parasite lipid sources are scarce and the molecular mechanisms by which Toxoplasma acquires host cell lipids are largely unknown (Coppens 2006).To determine if Toxoplasma infection influences the host lipid status in vivo, serum lipid levels were assessed at different time points during infection in wild-type mice. Parasites -The low virulence BGD-1 strain (human origin type-2 strain) characterized in our laboratory (Djurković-Djaković et al. 2006) was used for experimental infections. Mice were inoculated by oropharyngeal gavage with eight cysts, an inoculum shown to be non lethal for > 90% of the mice during the first eight weeks post-infection (p.i.). MATERIAL AND METHODS MiceExperimental design -Two different experimental models were used. To examine the kinetics of the lipids at an individual level during Toxoplasma infection (model 1), animals were infected (n = 54) or left uninfected (n = 18) to serve as controls. Both groups were bled at days zero and 42 p.i. and subgroups of 6-12 mice were bled on alternating weeks at days 7, 14, 21 and 28, for the measurement of total Chl, high density lipoprotein (HDL), LDL and triglyceride levels. At day 42 p.i., mice were euthanized and their brains were harvested for cyst enumeration. The experiment was performed twice and the data shown are their cumulative results.Model 2 was designed to correlate blood lipid levels with adiponectin as well as with local changes in tissues. Groups of infected (n ≥ 9) and control (n = 6) mice were euthanized at days zero, 14 and 42 p.i. and blood was drawn for the measurement of lipids as above and of adiponectin. Brains and livers were harvested for future tissue and molecular analyses.Lipids -Total Chl, HDL, LDL and triglycerides were measured on the Olympus AU 400 biochemical analyzer, according to the manufacturer's recommendations.