<Emphasis Type="Italic">Toxoplasma gondii</Emphasis> antibody profile in HIV-infected pregnant women and the risk of congenital toxoplasmosis

The purpose of this study was to investigate the antibodies to Toxoplasma gondii in human immunodeficiency virus (HIV)-infected pregnant women and to determine the association between serological profile and the risk of congenital toxoplasmosis. The study, conducted in a public maternity ward from May 2002 to April 2005, included all HIV-infected women who delivered live infants during the 36 months, and, as a control group, all HIV-negative women that delivered live infants in the first 12 months of the study. Antibodies to T. gondii were detected in 1,624 of 2,421 HIV-negative women (67%; 95% confidence interval [CI] 65–69%) and in 121 of 168 HIV-infected patients (72%; 95% CI 65–79%). A total of 547 HIV-negative and 103 HIV-infected patients were tested at delivery and had positive T. gondii-specific IgG. In HIV-negative women, the median of the specific IgG concentration was 79 (interquartile range 38–160), and in HIV-infected patients, it was 283 (interquartile range 94–704) (P < 0.001). In the group of co-infected women, the only infant with congenital toxoplasmosis was born to a mother with acute toxoplasmosis infection acquired during pregnancy who did not have a high specific IgG concentration or a positive result for specific IgM. We concluded that high T. gondii-specific IgG values were much more frequent among HIV-infected pregnant women, but it did not translate into an increased risk of maternal–fetal transmission of toxoplasmosis.     

Antibody response of HIV-infected patients to latent,cerebral and recently acquired toxoplasmosis

The aim of this longitudinal study with 626 HIV-infected patients was to evaluate the capability of serological tests in diagnosing the presence of Toxoplasma gondii infection in HIV-infected patients, as well as the potential impact of various treatment regimes on serological results. Low IgG antibody levels and stable or declining titres predominated. IgM positivity occurred in ten patients (one seroconversion, seven latent, two cerebral toxoplasmosis). Complement fixation test (CFT) titres ≥1:32 imply that the relative risk of cerebral toxoplasmosis is 6.84 (95% confidence interval [CI] 1.44–32.5) but with a predictive value of only 14.0% (95% CI 5.3–27.9). Values of specific antibodies are not biassed by antiretroviral treatment and/or prophylaxis for toxoplasmosis, and the detection of specific antibodies is very useful in the identification of T. gondii infection in the HIV-infected population, but the role of serology in predicting the clinical manifestation of T. gondii infection is limited.     

Detection of toxoplasma antibodies in sera of Salmonidae by ELISA

Toxoplasma gondii is a protozoan parasite with a worldwide distribution. It is capable of infecting all warm-blooded animals. Toxoplasmosis was not considered a waterborne zoonoses, but recently, it has been reported in many marine mammals. Coastal pollution by sewage from humans and pets has been suggested as a source for toxoplasma infection in these animals. Recent reports of toxoplasmosis in marine mammals raise concern that cold-blooded marine animals are potential sources of T. gondii infection. Conversely, the increasing proclivity for eating fish, crabs, shrimp, and mollusks—raw, undercooked, smoked, or dried—facilitates zoonoses infections caused by protozoan microorganisms; and one of them is toxoplasma. Detection of antibodies against T. gondii can be achieved by different serological tests such as enzyme-linked immunosorbent assay (ELISA). To determine whether toxoplasmosis has a role in Salmonidae infection, which is the most common seafood in Shahrekord district, this research was carried out on 50 Salmonidae aged 4 months (weight 700 ± 200 g). ELISA was performed on serum samples for detecting T. gondii-specific immunoglobulin M (IgM) and immunoglobulin G (IgG). As a result, toxoplasmic IgM antibody was detected in five of 50 samples (cut-off value of ≥0.183). Based on these findings, we believe that Salmonidae may be susceptible to primary T. gondii infection. While there is still no evidence of T. gondii transmission from cold-blooded sea animals to human via consuming their meat or other products, further research can be done to prove the possibility of this hypothesis.     

Seroprevalence and sources of Toxoplasma infection among indigenous and immigrant pregnant women in Taiwan

Investigation on seroprevalence and risk factors of Toxoplasma gondii infections among indigenous and immigrant pregnant women in Mid-Taiwan showed that anti Taxoplasma-specific IgG antibody counts were significantly higher in indigenes (40.6%) than in immigrants (18.2%), with an odds ratio of OR = 3.34 (95% CI: 1.93–4.80). The titre of Taxoplasma-specific IgG was also significantly higher in indigenes than in immigrants (P < 0.001). Differences of living styles for Toxoplasma infection between the two groups were drinking untreated water (OR = 2.34, 95% CI: 1.36–4.02), consumption of raw/undercooked meats (OR = 10.11 95% CI: 4.92–20.78), especially raw/undercooked pork (P = 0.000), or raw/undercooked viscera (OR = 9.16, 95% CI: 2.97–27.94), contact with cats (OR = 5.69, 95% CI: 2.83–11.47), or soil (OR = 2.55 95% CI: 1.72–3.80). Differences of risk factors for Toxoplasma infection in terms of positive IgG in the two groups were consumption of raw/undercooked meats (P = 0.005) especially raw/undercooked pork (P = 0.004), and contact with cats (P = 0.013) or soil (P = 0.028). It is concluded that seroprevalence of Toxoplasma infection is higher in indigenous pregnant women and related to their living styles. To prevent congenital toxoplasmosis, health education seems required.     

Reference values for the erythrocytic profile of Anak 2000 broilers and Lohmann brown pullets in Nsukka,Eastern Nigeria

Reference values for the erythrocytic indices are vital for the diagnosis of anaemia and polycythemia and also for the assessment of efficacy of therapy instituted to correct these abnormalities. This study determined the reference values for the packed cell volume (PCV), haemoglobin concentration (HbC), red blood cell (RBC) counts, mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH) and mean corpuscular haemoglobin concentration (MCHC) of Anak 2000 broilers (A2B) at 14-day intervals for 84 days and Lohmann brown pullets (LBP) at 21-day intervals for 147 days. A total of 120 chickens were used for the study (60 A2B and 60 LBP), and all haematological determinations followed standard procedures. Results of the determinations on the A2B showed that PCV and HbC did not significantly vary (p > 0.05) with age and had a low correlation with age (r = −0.22 and r = 0.15, respectively), but RBC counts increased with and positively correlated with age (r = 0.78), while MCV and MCH decreased with and were strongly inversely correlated with age (r = −0.80 and r = −0.84, respectively), and MCHC did not follow a definite pattern. For the LBP, there were no significant variations (p > 0.05) associated with age in the PCV, RBC counts, MCV, MCH and MCHC up to 105 days of age; the significant variations (p < 0.05) obtained after day 105 were associated with pre-lay and egg-laying. The HbC of the LBP did not significantly vary (p > 0.05) all through the study. When compared with findings in similar studies as reported by other investigators, some of the values obtained in this study and the patterns of change in relation to age were in agreement while some others contrasted, probably because of differences between the strains and the climatic/environmental conditions under which the chickens were raised.     

Haematology of the German Shepherd dog in a humid tropical environment

To study the haematology of the German Shepherd breed of dog in a humid, tropical environment, an experiment was conducted to elucidate the effects of sex, age, and breed on the erythrocyte and leukocyte values of this species. There were no significant (p > 0.05) gender-related differences in the values of red blood cell counts (RBC), packed cell volume (PCV), haemoglobin (Hb) concentration, mean corpuscular haemoglobin concentration (MCHC), mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH), total and differential white blood cell counts (WBC) of the German Shepherd dog. The study also revealed that the adult German Shepherd dog (between 3 and 5 years old) had significantly higher RBC, total WBC, PCV and Hb, MCV, MCH, MCHC and lymphocyte values than a younger animal (between 8 and 15 weeks old). However, neutrophil, monocyte and eosinophil counts were similar (p > 0.05) in the two age groups. Although there were no breed differences in the erythrocyte values between the Nigerian local dog and the German Shepherd dog, the WBC and neutrophil counts were however significantly higher in the Nigerian dog. This study revealed that although there were no gender or breed differences in the erythrocyte values of the German Shepherd dog, there were some age-related differences.     

Changes in the haematological values of avian blood samples stored at varying temperatures for a period of up to 72 hours

Avian blood samples collected from remotely located farms may not always reach the laboratory for analysis immediately upon collection. This study investigated the changes that occur in the packed cell volume (PCV), haemoglobin concentration (HbC), red blood cell (RBC) counts, mean corpuscular values and white blood cell (WBC) counts of avian blood samples stored at refrigerator (4°C), room (average of 29°C) and incubator (37°C) temperatures across a storage period of 72 h. Blood samples for the study were collected from 12 adult chickens. All haematological determinations were carried out on the blood samples individually immediately upon collection to obtain the baseline value (BV) and thereafter at specific time intervals across the 72-h duration of storage (DOS). Results showed that for the samples stored at 4°C, there were no significant changes (p > 0.05) from the BV in the PCV, HbC, RBC counts, mean corpuscular haemoglobin (MCH) and mean corpuscular HbC (MCHC) all through the 72-h DOS, but the mean corpuscular volume (MCV) significantly increased (p < 0.01), while WBC counts significantly decreased (p < 0.01) from their BV after 30-h DOS. For the blood samples kept at 29°C, there were no significant changes (p > 0.05) from the BV in the HbC, RBC counts and MCH all through the 72-h DOS, but PCV and MCV significantly increased (p < 0.01) from their BV after 18 and 12-h DOS, respectively, while MCHC and WBC counts significantly decreased (p < 0.01) from their BV after 12 and 18-h DOS, respectively. For the samples kept at 37°C, there were significant changes (p < 0.01) from the BV in the MCHC after 9-h DOS, MCV after 12-h DOS, PCV and WBC counts after 18-h DOS, HbC and RBC counts after 48-h DOS and MCH after 60-h DOS. All changes in PCV, MCV and MCH were directly correlated with DOS, while the changes in HbC, RBC counts, MCHC and WBC counts were inversely correlated with the DOS. It was concluded that for avian blood samples stored at 4°C, reliable results (results not significantly different from the BV) can be obtained for the PCV, HbC, RBC counts, MCH and MCHC for up to 72-h DOS and for MCV and WBC counts for up to 30-h DOS; while for samples stored at 29°C, reliable results for HbC, RBC counts and MCH can be obtained for up to 72-h DOS and for MCV and MCHC for up to 12-h DOS but for PCV and WBC counts for up to 18-h DOS. Samples kept at 37°C can give reliable MCHC for up to 9-h DOS, MCV for up to 12-h DOS, PCV and WBC counts for up to 18-h DOS, HbC and RBC counts for up to 48-h DOS and MCH for up to 60-h DOS. A preliminary report of this study has been presented at the 43rd Annual Congress and Regional Conference of the Nigerian Veterinary Medical Association, Minna, Nigeria, November 6–10, 2006.     

Seroepidemiology of Toxoplasma gondii, Neospora caninum, and Leishmania spp. infections and risk factors for cats from Brazil

The seroprevalence of infection by Toxoplasma gondii, Neospora caninum, and Leishmania spp. was detected through an indirect immunofluorescence in 70 cats from the Andradina Municipality, S?o Paulo State, Brazil. Anti-T. gondii antibodies (titer >64) were detected in 15.7% (11/70) of animals, whereas positivity for N. caninum (titer 16) was not observed in any animal. Of the cats from urban and rural areas, 10.4% (5/48) and 27.2% (6/22) were positive for T. gondii, respectively. Breed, age, food, and contact with animals of other species were significant for considering the positivity for T. gondii (P ≤ 0.0001). Cats having access to streets (17.1%, 11/64), cats cohabiting with rats (19.6%, 10/51), and cats feeding on homemade food and raw milk (27.2%, 6/22) were positive for T. gondii. In addition, 4.2% (3/70) of the cats were positive for Leishmania spp. by ELISA technique and negative by IFAT without coinfection with T. gondii and Leishmania spp. There was no serological positivity against feline immunodeficiency virus or feline leukemia virus. In conclusion, T. gondii infection in part of the feline population from Andradina is not linked to immunosuppressions or coinfections but probably to postnatal infection in association with the type of diet and presence of rats.     

Measurement of some haematological characteristics of the wild carp

The aim of the present study was to obtain a basic knowledge of the haematology and the influence of sex on some blood parameters of wild carp (Cyprinus carpio) spawners. Haematological indices [red blood cells (RBC), white blood cells, haemoglobin (Hb), packed cell volume (PCV), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC) and leucocyte differential count] were measured in one blood sample from 24 females (weight, 1.3 ± 0.1 kg; length, 47.4 ± 1.06 cm) and 27 males (weight, 1.265 ± 0.105 kg; length, 46.9 ± 0.8 cm). The highest haematocrit (PCV), haemoglobin concentration (Hb), RBC, MCH and MCHC were found for males. The highest leucocyte differential were also found for females. Statistical analysis revealed that differences in haematological parameters between males and females fish were not significant.     

Immunogenic characterization of the chimeric surface antigen 1 and 2 (SAG1/2) of <Emphasis Type="Italic">Toxoplasma gondii</Emphasis> expressed in the yeast <Emphasis Type="Italic">Pichia pastoris</Emphasis>

In this study, we successfully expressed a chimerical surface antigen 1 and 2 (SAG1/2) of Toxoplasma gondii in Pichia pastoris. Eighty human serum samples, including 60 from confirmed cases of toxoplasmosis, were tested against the purified recombinant SAG1/2 in Western blots. Results of Western blots targeted at Toxoplasma IgG and IgM showed that the recombinant SAG1/2 reacted with all sera from the toxoplasmosis cases but none with the Toxoplasma-negative serum samples. These results showed that the P. pastoris-derived recombinant SAG1/2 was sensitive and specific and suitable for use as antigen for detecting anti-Toxoplasma antibodies. To further investigate the immunological characteristic of the recombinant protein, the recombinant SAG1/2 was injected subcutaneously into BALB/c mice, and their serum was tested against total protein lysate of T. gondii. Mice immunized with the recombinant SAG1/2 reacted specifically with the native SAG1 and SAG2 of T. gondii. Significant proliferation of splenocytes stimulated with tachyzoite total protein lysate was observed in vaccinated BALB/c mice but not in those from negative control mice. Specific production of IFN-γ, the Th1-type cytokines, was also found in stimulated splenocytes from vaccinated mice. These results show that the chimeric protein recombinant SAG1/2 can elicit a Th1-associated protection against T. gondii infections in mice. Finally, vaccinated mice were significantly protected against lethal challenge with live T. gondii RH strain tachyzoites (P < 0.005), and their survival time increased significantly compared to the negative control.     

Evaluation of a Commercial IgG/IgM Western Blot Assay for Early Postnatal Diagnosis of Congenital Toxoplasmosis

The aim of this study was to evaluate a commercial Western blot IgG/IgM assay for use in the early serological diagnosis of congenital toxoplasmosis. This assay compares the immunological profile of mother and infant and allows differentiation between passive transmitted maternal antibodies and newly synthesized antibodies of the infant within the first 3 months of life. Over a 6-year period (1995–2001), the sera from 169 mothers and their 175 offspring (6 had twins) were examined for specific anti-Toxoplasma gondii IgG, IgM and IgA antibodies with an enzyme-linked immunosorbent assay or an immunosorbent agglutination assay. All mothers had primary Toxoplasma infection during pregnancy. Serological and clinical follow-up of the infants during the first year of life confirmed 36 cases of congenital toxoplasmosis. In 139 cases, infection could be ruled out. Three hundred fifty-one paired samples from 175 mother-child pairs were tested retrospectively for IgG and IgM patterns by Toxoplasma Western blot IgG/IgM (LDBIO Diagnostics, France). The results of conventional serological analysis (immunosorbent agglutination assay or enzyme-linked immunosorbent assay) to detect IgM or IgA were compared with the results of the Toxoplasma Western blot IgG/IgM on samples obtained within the first 3 months of life. The performance of the combination of the two methods was also assessed. At birth, the sensitivity values of conventional serological analysis and the Toxoplasma Western blot were 52% and 67%, with specificity values being 99% and 96%, respectively. Combination of the Western blot and conventional serological analysis increased the sensitivity at birth to 78% and within the first 3 months of life to 85%. Overall, the combination of both methods detected 94% of congenital infections. Therefore, this commercial Western blot represents a useful tool for early postnatal diagnosis of congenital toxoplasmosis. Electronic Publication     

Studies on the sexual behaviour, haematology and spermatogenesis of male rabbits infected with Trypanosoma brucei brucei

A total of 24 crossbreed buck rabbits (New Zealand White × chinchilla) were used to evaluate the effect of experimental infection with Trypanosoma brucei on symptoms, sexual behaviours, haematology and spermatogenesis. The rabbits were divided into two groups (A and B) of 12 rabbits each. Group A rabbits were infected with 1.25 × 10⁶ of T. brucei, whereas group B served as the uninfected control. The trypanosomes were detectable in the blood of all the infected bucks by day 7 post-infection (PI) with mean pre-patent period of 4.7 ± 0.85 days. The red blood cell (RBC) and packed cell volume (PCV) decreased significantly (P < 0.05) from day 8 to 28 PI. The values however improved from day 36 PI and were similar to the uninfected control. The reverse was the case of parasitaemia. Two rats died at the peak of the decrease in RBC and PCV and increase in parasitaemia. There was also significant (P < 0.05) loss in live and testis weights, reduced libido and impaired spermatogenesis in the infected group. The infected bucks showed clinical signs similar to that reported in other trypanosome-infected animals. It is concluded that susceptibility of crossbreed rabbits usually kept in Africa to pathogenic trypanosomes is characterised by an acute stage manifested by anaemia, high parasitaemia and death and chronic stage manifested by improved PCV and RBC, very low parasitaemia but high tissue damage and low productivity. Control of this disease in endemic areas for purpose of commercial rabbit production is advocated.     

Serum protein alterations in dogs naturally infected with <Emphasis Type="Italic">Toxoplasma gondii</Emphasis>

We conducted this study to describe the serum electrophoretic pattern in dogs associated with the infection of Toxoplasma gondii (T. gondii). The serum protein pattern of 25 dogs with confirmed T. gondii infection and 15 clinically healthy dogs were evaluated using native polyacrylamide gel electrophoresis. Albumin, alpha-1 globulin, alpha-2 globulin, beta globulin, and gamma globulin bands were seen from the serum electrophoresis of infected and healthy dogs. Compared to the control group, significant decreases in the mean percentages of albumin (from 46.1 ± 7.2 to 40.8 ± 4.5%, P < 0.05), alpha-1 globulin (from 3.9 ± 0.4 to 0.8 ± 0.2%, P < 0.001), alpha-2 globulin (from 9.0 ± 0.4 to 8.3 ± 0.8%, P < 0.01), and beta globulin (from 18.4 ± 1.2 to 12.1 ± 0.6%, P < 0.001) in the infected group were determined. In contrast, gamma globulin fraction was significantly higher in infected dogs (38.1 ± 4.6%) than in control dogs (22.7 ± 7.2%; P < 0.001). Moreover, significant correlations were determined between the percentages of the albumin and gamma globulin fractions and liver enzyme tests including aspartate aminotransferase and alanine aminotransferase in infected dogs; however, no correlation was observed for the other protein fractions. In conclusion, marked alterations in serum protein pattern associated with strong modifications of serum protein concentrations are in accordance with the hepatic injury as affirmed by liver enzyme tests that were demonstrated in the canine toxoplasmosis. These findings showed that serum protein electrophoresis can be used in the diagnosis and prognosis of canine toxoplasmosis as a supplementary analysis in combination with serological, clinical, and laboratory findings of this disease.     

Seroprevalence of and risk factors for Toxoplasma gondii antibodies among asymptomatic blood donors in Egypt

A cross-sectional study was conducted to evaluate the seroprevalence of and risk factors for Toxoplasma gondii antibodies in 260 blood donors seen at blood banks in Mansoura University Hospital, Egypt. Blood donors were interviewed about sociodemographic characteristics and risk factors for T. gondii infection. A blood sample was taken to document their T. gondii antibody status using enzyme-linked immunosorbent assay. Overall, 155 (59.6%) of 260 blood donors were positive for anti-T. gondii IgG antibodies. Multivariate logistic regression analysis showed a significant association between T. gondii seropositivity and eating meat by-products (luncheon/shawerma) (adjusted odds ratio [OR] 80.82 [95% CI 18.62–350.81], P < 0.0001) or being non-educated (adjusted OR 32.25 [95% CI 7.46–139.44], P < 0.0001). These findings highlight that T. gondii is prevalent among blood donors in Egypt.     

Performance of a Western Blot Assay to Compare Mother and Newborn Anti-Toxoplasma Antibodies for the Early Neonatal Diagnosis of Congenital Toxoplasmosis

 The aim of this study was to retrospectively evaluate the performance of a Western blot assay to compare mother and newborn anti-Toxoplasma gondii antibodies for the early neonatal diagnosis of congenital toxoplasmosis. Since specific anti-Toxoplasma IgM or IgA is detected inconstantly at birth in the neonate, the diagnosis of congenital toxoplasmosis is often delayed until 6–9 months, after IgG titers have been observed persistently. In this study, 81 paired samples from 60 mother/child pairs were tested for IgG and IgM patterns. All mothers had (or were strongly suspected to have) acquired toxoplasmosis during pregnancy. Specific IgM and IgA were simultaneously detected by immunocapture tests, and IgG was titrated. A serological and clinical follow-up of infants was conducted during the first year of life until the diagnosis of congenital toxoplasmosis could be either confirmed or ruled out. Seventeen of the 60 newborns were congenitally infected. Specific IgM or IgA was detected by immunocapture at birth in 76.5% and 70.6% of cord sera from infected neonates, respectively, with an equal specificity of 77.5%. Comparative Western blot allowed the detection of neosynthesized IgG and IgM in the cord blood of 50% and 78.6% of infected infants, respectively, with a specificity of 100%. The combination of IgA and IgM immunocapture tests, the analysis of IgG and IgM Western blot patterns, and the combination of both techniques allowed the detection of 94%, 94%, and 100% of cases within the first 3 months of life, respectively. In conclusion, Western blotting seems to be a useful complementary tool for the early postnatal diagnosis of congenital toxoplasmosis.     

Change in haematological profile of pregnant camels (Camelus dromedarius) at term

Haematological parameters of 28 pregnant camels (Camelus dromedarius) were compared with those of 32 non-pregnant camels (C. dromedarius). The parameters compared were: total erythrocytes count (RBC), haemoglobin (Hb), packed cell volume (PCV), mean corpuscular volume (MCV), mean corpuscular haemoglobin, mean corpuscular haemoglobin concentration and total leucocyte count (TLC). Results obtained indicate that RBC, Hb and PCV decreased in the later stages of pregnancy while TLC remained unchanged. Calculated indices revealed a significant increase in MCV (p < 0.02) of pregnant camels.     

Seroprevalence of Toxoplasma gondii infection among immigrant and native pregnant women in Eastern Spain

In European countries, toxoplasma antenatal screening is recommended to prevent toxoplasmosis. The seroprevalence of these infections in immigrants can be different than in native population. From February 2006 to June 2010, a cross-sectional study was carried out in all pregnant women attended at a reference unit in Elche, Spain. An enzyme immunoassay was used for detection of IgG antibodies against Toxoplasma gondii. For each immigrant woman, one Spanish pregnant woman of the same age cared for in the same day was recruited (Spanish control group). A total of 1,627 migrant pregnant women participated in this study. The adherence to screening among migrants was 91.9% (95% CI, 90.5–93.1%), similar than that found in Spaniards (92.2%; 95% CI, 90.8–93-4%). Among migrant women, 619 were positive for IgG anti-T. gondii antibodies (41.4%; 95% CI, 38.9–43.9%), compared with 12.0% (95% CI, 10.5–13.8%) among Spaniards (odds ratio (OR), 5.2 (95% CI, 4.3–6.3). Seroprevalence in pregnant women from Latin America, northern Africa, Eastern Europe, Africa Sub-Saharan and Western Europe was higher than in the Spanish control group (OR, 5.4, 5.8, 6.5, 5.4, and 2.4, respectively; p < 0.001). No Asian pregnant woman was immune. Seroprevalence increased with increasing age in migrant pregnant women: 15–25 years, 38.2%; 26–35 years, 40.7%; and 36–45 years, 52.8%. The seroprevalence of T. gondii infection in migrant pregnant women living in Spain was higher than in the native population. However, no cases were found in Asian immigrants, highlighting the importance of primary prevention of this infection in pregnant women coming from that geographic region.     

Serodiagnosis of acute toxoplasmosis using a recombinant form of the dense granule antigen GRA6 in an enzyme-linked immunosorbent assay

We developed an indirect enzyme-linked immunosorbent assay (ELISA) for the serological diagnosis of acute toxoplasmosis that used the recombinant granule antigen GRA6-GST as diagnostic antigen for the detection of IgG antibodies to Toxoplasma gondii in human sera. A total of 431 sera obtained from 336 patients with acute and chronic toxoplasmosis and from patients who were not infected with T. gondii were tested. Sera from patients with acute T. gondii infection, chronic infection, and no infection showed different absorbance values. For discrimination between the presence and the absence of acute toxoplasmosis the assay reached a specificity of 99.6%. Only one of the sera without significant anti-T. gondii. IgM antibodies showed a positive reaction to rGRA6-GST. The assay showed good intra- and interassay reproducibility (CV 6%/14%). We included a glutathione S-transferase (GST)-IgG enzyme immunoassay as a control assay in this study. Only 7 (4%) of 159 random sample sera reacted positively with GST. Received: 22 November 1997 / Accepted: 26 March 1998     

Borrelia burgdorferi VlsE antigen for the serological diagnosis of Lyme borreliosis

In this study, raising and development of antibody response to Borrelia burgdorferi infection in 66 Italian patients suffering from culture-confirmed Lyme borreliosis erythema migrans (EM) was investigated. Sixty-two of 66 cultures obtained from biopsies were identified as B. afzelii by PCR. A total of 175 serially collected serum samples were tested by using two different sets of commercial assays: Enzygnost Lyme link VlsE/IgG and Enzygnost Borreliosis IgM (DADE Behring, Marburg, Germany) and LIAISON Borrelia IgG and IgM (Diasorin, Saluggia, Italy). Considering only samples obtained at first presentation when EM was clinically evident, 49/66 patients (72.4%) were IgG or IgM positive by Enzygnost, whereas 33/66 (50.0%) patients were IgG or IgM positive by LIAISON. Taking into account the follow-up period, eight patients sero-converted for IgG or IgM by Enzygnost and four by LIAISON. Similar and very good specificity values were obtained by all methods. Testing sera obtained from blood donors (n = 300) and from patients suffering from some of the most common biological conditions possibly resulting in false-positive reactivity in Lyme disease serology (n = 100) showed that Enzygnost Lyme link VlsE/IgG was the more specific (98.3%), followed by LIAISON Borrelia IgG (96.5%), and considering IgM tests, Enzygnost Borreliosis IgM showed to be 95.3%% specific, whereas the LIAISON Borrelia IgM was 92.8% specific. Recombinant VlsE antigens obtained from all three B.burgdorferi genospecies pathogenic to humans (included in Enzygnost Lyme link VlsE/IgG) greatly improved serodiagnosis of Lyme disease.     

Prevalence of latent toxoplasmosis and serological diagnosis of active infection in HIV-positive patients

The seroprevalence of latentToxoplasma gondii infection was determined in a cohort of 715 HIV-positive patients followed up at an HIV outpatient clinic. Using indirect immunofluorescence and direct agglutination assays for detecting IgG, the prevalence of anti-Toxoplasma gondii antibodies was shown to be 50 %. During a four-year period, clinically apparent acute toxoplasmosis occurred in 47 patients (43 with cerebral, 3 with ocular and 1 with bone marrow toxoplasmosis) among the 360 patients positive for anti-Toxoplasma gondii IgG and in one patient (with cerebral toxoplasmosis) among the 355 patients who were serologically negative. A significant rise in IgG levels could be shown during acute toxoplasmosis episodes in only 30 % of patients, compared with 3 % of patients without active toxoplasmosis. During acute toxoplasmosis, IgM antibodies were detected in only two patients (6 %) by an immunosorbent agglutination assay and in one (3 %) by an enzymatic immunocapture assay. Specific IgA was detected by a non-enzymatic immunocapture assay in six patients (18 %) during acute episodes. The very high predictive value (99.7 %) of a negative IgG test remains the best serological parameter for excluding an acute episode of toxoplasmosis in HIV-positive patients.