No abstract

BackgroundToxoplasma gondii is a zoonotic parasite of global importance. The outcome of infection in humans can depend on a number of factors including the infecting stage of the parasite, inoculating dose and virulence of the infecting strain. Molecular epidemiological studies have demonstrated an abundance of atypical strains of T. gondii in South America, many of which have been associated with more severe sequelae of infection. The aim of this study was to compare the virulence of T. gondii strains isolated in the Caribbean to a virulent Brazilian strain and an avirulent European strain.MethodsOne hundred and twenty Swiss CD-1 mice were split into 8 groups of 15 mice and each group was inoculated with 200 tachyzoites of one of 8 isolates, comprising ToxoDB genotypes #1, #141, #265, #13, #3 and #6. Five mice per group were euthanized at day 8 post-inoculation (p.i.) and parasite burden was determined in heart, lungs and eyes using quantitative PCR. Lungs and brain were also examined by histopathology and immunohistochemistry. The remaining 10 mice per group were part of a survival experiment to assess virulence. DNA was extracted from tachyzoites of each of the 8 T. gondii isolates and genotyped at four ROP gene loci, including ROP5, ROP16, ROP17 and ROP18 to look for association with markers of virulence.ResultsInfection with ToxoDB genotype #13 from the Caribbean resulted in 100% of mice being euthanized which was comparative to infection with the virulent Brazilian strain (ToxoDB genotype #6). Significantly higher parasite burdens were recorded in the lungs and eyes of mice infected with ToxoDB genotypes #13 and #6. Genotyping of ROP loci revealed that the virulent Caribbean isolates had a different ROP18/ROP5 allelic profile (3/1) to the virulent Brazilian isolate (1/3); however, the avirulent Caribbean isolate (ToxoDB genotype #1) had the same ROP18/ROP5 profile as the avirulent European isolate (ToxoDB #3) (both 2/2). Caribbean isolates of intermediate virulence (ToxoDB #141 and #265) all had the same ROP18/ROP5 allelic profile (2/2).ConclusionsIsolates from the Caribbean with ToxoDB genotype #13 were acutely virulent for mice and comparable to a known virulent Brazilian isolate. The ROP protein allelic profile of the virulent Caribbean and Brazilian isolates differed indicating that perhaps other factors are involved in predicting virulence. Understanding virulence is important for predicting disease outcome in humans and may also aid vaccine design as well as drug discovery.

No abstract

No abstract

In a double-blind controlled study, oral acyclovir has been compared to a placebo in a series of 39 consecutive patients undergoing bone marrow transplantation. A dose of 200 mg was given every 6 h from day 8 to day 35 after transplantation. Pharmacokinetic studies have shown the good absorption of the drug despite intestinal damage related to chemoradiotherapy or gut graft-versus-host disease (GVHD); there was no sign of toxicity. The protection against herpes simplex virus (HSV) infection was complete in the treated group when compared to the control group even in patients with high anti-HSV antibody titres. The same protection was observed against cytomegalovirus (CMV) infection. The incidence of HSV and CMV was the same in both groups after treatment ended. This study confirms the efficacy of acyclovir against HSV infection and possibly against CMV infection when it is given prophylactically after bone marrow transplantation.

No abstract

The purpose of this study was to perform genotypic characterization and to evaluate the virulence of Toxoplasma gondii obtained from aborted fetuses in an abortion outbreak in goats from northeastern Brazil. Brain samples from 32 fetuses were submitted to mouse bioassay for T. gondii isolation. Two isolates were obtained and subjected to genotypic characterization. Isolate virulence was evaluated using murine model in different doses (from 10 to 10 tachyzoites/mL). In genotyping, both isolates were classified as clonal lineage type II (genotype #1 ToxoDB) and showed to be virulent for mice. This is the first description of genotype #1 in cases of goat abortion, showing the circulation of virulent T. gondii isolate producing reproductive disorders in pregnant goat.

Toxoplasmosis, caused by the protozoan Toxoplasma gondii, is zoonotic disease and is one of the most important foodborne parasitic diseases globally. The prevalence in humans is highly variable, being influenced by cultural habits, socioeconomic, and environmental conditions. The objective of this study was to estimate the prevalence of T. gondii infection in humans on the archipelago of Fernando de Noronha, Pernambuco State, Brazil, and to identify the risk factors associated with this infection. The seroprevalence of immunoglobulin G anti-T. gondii antibodies was 50.4% (172/341, 95% CI: 45.2%–55.7%). Factors associated with the infection were consumption of well water or rainwater (odds ratio [OR]: 2.43, p=0.020) and consumption of game meat (OR: 1.80, p=0.026). This is the first study to provide epidemiological information of T. gondii infection among the residents of the Island of Fernando de Noronha, revealing a considerable antibody seroprevalence in this population. This study provides information for the adoption of prevention and control measures in island environments.