Strongyloides infection screening in transplant candidates: What is the best strategy?

BACKGROUND: The potential that Strongyloides stercoralis infection has to cause major morbidity and high mortality when the disseminated form occurs in transplant patients is of particular concern. METHODS: In this study, the objective was to observe S. stercoralis infection in patients who are candidates for transplantation by using parasitological, serological, and molecular techniques and to propose an algorithm for the detection of that infection in transplant candidates. RESULTS: By parasitological techniques, 10% of fecal samples were positive. Anti-Strongyloides antibodies immunoglobulin G were detected in 19.3% and 20.7% of patients by immunofluorescence assay and enzyme-linked immunosorbent assay, respectively. S. stercoralis DNA was observed in 17.3% of samples by conventional polymerase chain reaction and 32.7% of samples by quantitative polymerase chain reaction (qPCR). CONCLUSION: The set of results allows us to reinforce that a positive result by parasitological techniques and/or qPCR indicates that the specific treatment should be applied. However, the improvement of diagnostic techniques may suggest changes in the screening for strongyloidiasis in these patients.

Evaluation of aversive behavior in Rattus norvegicus experimentally infected by two distinct strains of Toxoplasma gondii (ME49 and VEG): study of epigenetic markers.

BACKGROUND: Behavioral changes in Rattus norvegicus infected with two strains of Toxoplasma gondii (ME49 and VEG) were investigated. METHODS: Rats were evaluated for motor activity and aversion or attraction to cat urine 60 days after infection. After euthanasia, arginine-vasopressin gene methylation in the central nervous system was evaluated. RESULTS: A significant difference was observed in the methylation of the arginine-vasopressin promoter gene between rats infected with the ME49 and VEG strains. CONCLUSIONS: Although differences were not observed in many parameters, significant differences were observed in the methylation of the arginine-vasopressin promoter gene in rats infected with the two studied strains.

Immune complexes as a tool for strongyloidiasis immunodiagnosis in kidney and liver transplant candidate.

Strongyloidiasis is a chronic and asymptomatic infection in immunocompetent patients. Immunocompromised patients, such as organ transplant candidates, can develop severe forms of this disease, and the best way to prevent progression to these forms is early diagnosis. Serological techniques using specific IgG and immune complexes (IC) detection can help in the diagnosis of these patients. This study aimed to detect specific anti-Strongyloides IC and IgG antibodies in kidney transplant (KT) and liver transplant (LT) candidates. A total of 100 blood samples was collected from transplant candidates (50 blood samples each from KT and LT candidates). Serum was obtained and analysed using enzyme-linked immunosorbent assay for IC and IgG detections. The IC levels showed frequencies of 18% and 2% in the KT and LT groups, respectively, whereas anti-Strongyloides IgG was detected in 34% and 12% of KT and LT candidates, respectively. The correlation between IC and IgG detection is poor in KT candidates, while in LT candidates, there is a significant positive correlation. The detection of IC can be an additional tool for the diagnosis of strongyloidiasis, especially when associated with the detection of specific IgG anti-Strongyloides antibodies.

Evaluation of aversive behavior in Rattus norvegicus experimentally infected by two distinct strains of Toxoplasma gondii (ME49 and VEG): study of epigenetic markers

ABSTRACT Background: Behavioral changes in Rattus norvegicus infected with two strains of Toxoplasma gondii (ME49 and VEG) were investigated. Methods: Rats were evaluated for motor activity and aversion or attraction to cat urine 60 days after infection. After euthanasia, arginine-vasopressin gene methylation in the central nervous system was evaluated. Results: A significant difference was observed in the methylation of the arginine-vasopressin promoter gene between rats infected with the ME49 and VEG strains. Conclusions: Although differences were not observed in many parameters, significant differences were observed in the methylation of the arginine-vasopressin promoter gene in rats infected with the two studied strains.

Human Toxocariasis: 2010 to 2020 Contributions from Brazilian Researchers.

This is a review of the published contributions made by Brazilian researchers between 2010 and 2020 on the natural history of human toxocariasis and the effects of human toxocariasis on nonhuman paratenic hosts.

IgG reactivity with 40-35 kDa soluble and membrane antigen of Strongyloides venezuelensis in immunocompromised patients.

Immunocompromised patients constitute a risk group for the development of severe clinical forms of human strongyloidiasis. The diagnosis of this infection is primarily performed by parasitological techniques, but with low sensitivity. Serological techniques appear as an alternative, especially with heterologous antigens use. The aim of this study was to perform the Western blot technique by using S. venezuelensis infective third stage larva (iL3) soluble (TS) and membrane (TM) saline antigens to reveal immunoreactive bands in immunocompromised patients with strongyloidiasis. Serum samples from 117 parasitologically well-characterized patients were divided into four groups: S. stercoralis positive and immunocompetent (S + IC); S. stercoralis positive and immunocompromised (S + IP); negative and immunocompetent (S-IC); negative and immunocompromised (S-IP). A 40-35 kDa band was recognized by 100% of patients in the S + IC group in both antigenic fractions, and by 62.5% and 50% in the S + IP group using the TS and TM fractions, respectively. A 29 kDa band was recognized by 86.3% and 72.7% (for TS and TM, respectively) of patients in the S + IC group, and only by 12.5% of patients in the S + IP group on the TM antigen. Regardless of the patients' immunological condition, the 40-35 kDa band from S. venezuelensis was detected more frequently and can be used as an important marker to the immunodiagnosis of human strongyloidiasis.

Effect of sex on Toxocara canis larval migration to the cerebellum during experimental infection of Rattus norvegicus

The presence of Toxocara canis third instar larvae in the cerebellum of Rattus norvegicus may alter rodent behavior and movement. In this study, we investigated whether the sex of the rodent affects the migration of larvae to the cerebellum. Thirty-six Rattus norvegicus specimens (18 males and 18 females) were infected with 300 T. canis eggs and were euthanized after 60 days. The cerebellum was removed and treated with 0.5% HCl to recover the T. canis larvae. The number of larvae recovered from male rodents was significantly higher than in females, suggesting that the sex of the animal influences larval migration to the cerebellum

Experimental toxocariasis in BALB/c mice: relationship between parasite inoculum and the IgG immune response

BALB/c mice were inoculated with 5-500 Toxocara canis infective eggs, and bled at 15-120 days post infection (dpi) to evaluate the dynamics of IgG antibody response and larvae distribution. Positive results were observed in all occasions for every inoculum, and a direct proportional relationship between antibody detection and the parasitic load was observed. In samples collected at 60 dpi, detection of IgG was more intense, especially with the 50 and 500 egg doses; also, a correlation between antibody level and egg count was observed with these two inocula. At 120 dpi, a decrease in antibody titer was observed for all groups; and at the end of the experiment, larvae were recovered from carcass, liver and brain. In the liver, larvae were only found in mice inoculated with 500 T. canis eggs. In carcasses, these were recovered in all groups, and the group inoculated with 50 eggs showed the highest percentage of larvae in the brain.

Experimental toxocariasis in BALB/c mice: relationship between parasite inoculum and the IgG immune response.

BALB/c mice were inoculated with 5-500 Toxocara canis infective eggs, and bled at 15-120 days post infection (dpi) to evaluate the dynamics of IgG antibody response and larvae distribution. Positive results were observed in all occasions for every inoculum, and a direct proportional relationship between antibody detection and the parasitic load was observed. In samples collected at 60 dpi, detection of IgG was more intense, especially with the 50 and 500 egg doses; also, a correlation between antibody level and egg count was observed with these two inocula. At 120 dpi, a decrease in antibody titer was observed for all groups; and at the end of the experiment, larvae were recovered from carcass, liver and brain. In the liver, larvae were only found in mice inoculated with 500 T. canis eggs. In carcasses, these were recovered in all groups, and the group inoculated with 50 eggs showed the highest percentage of larvae in the brain.

DIAGNOSIS OF Strongyloides stercoralis INFECTION IN IMMUNOCOMPROMISED PATIENTS BY SEROLOGICAL AND MOLECULAR METHODS.

Strongyloidiasis is a potentially serious infection in immunocompromised patients. Thus, the availability of sensitive and specific diagnostic methods is desirable, especially in the context of immunosuppressed patients in whom the diagnosis and treatment of strongyloidiasis is of utmost importance. In this study, serological and molecular tools were used to diagnose Strongyloides stercoralis infections in immunosuppressed patients. Serum and stool samples were obtained from 52 patients. Stool samples were first analyzed by Lutz, Rugai, and Agar plate culture methods, and then by a quantitative real time polymerase chain reaction (qPCR). Serum samples were evaluated by an enzyme-linked immunosorbent assay (ELISA) using a soluble (AS) or a membrane fractions antigen (AM) obtained from alkaline solutions of the filariform larvae of Strongyloides venezuelensis. Of the 52 immunosuppressed patients, three (5.8%) were positive for S. stercoralis by parasitological methods, compared to two patients (3.8%) and one patient (1.9%) who were detected by ELISA using the AS and the AM antigens, respectively. S. stercoralis DNA was amplified in seven (13.5%) stool samples by qPCR. These results suggest the utility of qPCR as an alternative diagnostic tool for the diagnosis of S. stercoralis infection in immunocompromised patients, considering the possible severity of this helminthiasis in this group of patients.

IMMUNODIAGNOSIS OF HUMAN STRONGYLOIDIASIS: USE OF SIX DIFFERENT ANTIGENIC FRACTIONS FROM Strongyloides venezuelensis PARASITIC FEMALES.

The aim of this study was to evaluate six different antigenic fractions from Strongyloides venezuelensis parasitic females for the immunodiagnosis of human strongyloidiasis. Soluble and membrane fractions from S. venezuelensis parasitic females were prepared in phosphate-buffered saline (SSF and SMF, respectively), Tris-HCl (TSF and TMF, respectively), and an alkaline buffer (ASF and AMF, respectively). Serum samples obtained from patients with strongyloidiasis or, other parasitic diseases, and healthy individuals were analyzed by enzyme-linked immunosorbent assay (ELISA). Soluble fractions SSF, TSF, and ASF showed 85.0%, 75.0%, and 80.0% sensitivity and 93.1%, 93.1%, and 87.5% specificity, respectively. Membrane fractions SMF, TMF, and AMF showed 80.0%, 75.0%, and 85.0% sensitivity, and 95.8%, 90.3%, and 91.7% specificity, respectively. In conclusion, the present results suggest that the fractions obtained from parasitic females, especially the SSF and SMF, could be used as alternative antigen sources in the serodiagnosis of human strongyloidiasis.

Comparative Study of the Accuracy of Different Techniques for the Laboratory Diagnosis of Schistosomiasis Mansoni in Areas of Low Endemicity in Barra Mansa City, Rio de Janeiro State, Brazil.

Schistosomiasis constitutes a major public health problem, with an estimated 200 million people infected worldwide. Many areas of Brazil show low endemicity of schistosomiasis, and the current standard parasitological techniques are not sufficiently sensitive to detect the low-level helminth infections common in areas of low endemicity (ALEs). This study compared the Kato-Katz (KK); Hoffman, Pons, and Janer (HH); enzyme-linked immunosorbent assay- (ELISA-) IgG and ELISA-IgM; indirect immunofluorescence technique (IFT-IgM); and qPCR techniques for schistosomiasis detection in serum and fecal samples, using the circumoval precipitin test (COPT) as reference. An epidemiological survey was conducted in a randomized sample of residents from five neighborhoods of Barra Mansa, RJ, with 610 fecal and 612 serum samples. ELISA-IgM (21.4%) showed the highest positivity and HH and KK techniques were the least sensitive (0.8%). All techniques except qPCR-serum showed high accuracy (82-95.5%), differed significantly from COPT in positivity (P < 0.05), and showed poor agreement with COPT. Medium agreement was seen with ELISA-IgG (Kappa = 0.377) and IFA (Kappa = 0.347). Parasitological techniques showed much lower positivity rates than those by other techniques. We suggest the possibility of using a combination of laboratory tools for the diagnosis of schistosomiasis in ALEs.

EFFICACY OF NITAZOXANIDE AGAINST Toxocara canis: LARVAL RECOVERY AND HUMORAL IMMUNE RESPONSE IN EXPERIMENTALLY INFECTED MICE.

The efficacy of nitazoxanide (NTZ) against toxocariasis was investigated in an experimental murine model and results were compared to those obtained using mebendazole. Sixty male BALB/c mice, aged six to eight weeks-old, were divided into groups of 10 each; fifty were orally infected with 300 larvaed eggs of T. canis and grouped as follows, G I: infected untreated mice; G II: infected mice treated with MBZ (15 mg/kg/day) 10 days postinfection (dpi); G III: infected mice treated with NTZ (20 mg/kg/day) 10 dpi; G IV: infected mice treated with MBZ 60 dpi; G V: infected mice treated with NTZ 60 dpi; GVI: control group comprising uninfected mice. Mice were bled via retro-orbital plexus on four occasions between 30 and 120 dpi. Sera were processed using the ELISA technique to detect IgG anti- Toxocara antibodies. At 120 dpi, mice were sacrificed for larval recovery in the CNS, liver, lungs, kidneys, eyes and carcass. Results showed similar levels of anti- Toxocara IgG antibodies among mice infected but not submitted to treatment and groups treated with MBZ or NTZ, 10 and 60 dpi. Larval recovery showed similar values in groups treated with NTZ and MBZ 10 dpi. MBZ showed better efficacy 60 dpi, with a 72.6% reduction in the parasite load compared with NTZ, which showed only 46.5% reduction. We conclude that administration of these anthelmintics did not modify the humoral response in experimental infection by T. canis. No parasitological cure was observed with either drug; however, a greater reduction in parasite load was achieved following treatment with MBZ.

Efficacy of nitazoxanide against toxocara canis: larval recovery and humoral immune response in experimentally infected mice / Eficácia da nitazoxanida contra Toxocara canis: recuperação larvária e resposta imune humoral em camundongos experimentalmente infectados

SUMMARYThe efficacy of nitazoxanide (NTZ) against toxocariasis was investigated in an experimental murine model and results were compared to those obtained using mebendazole. Sixty male BALB/c mice, aged six to eight weeks-old, were divided into groups of 10 each; fifty were orally infected with 300 larvaed eggs of T. canisand grouped as follows, G I: infected untreated mice; G II: infected mice treated with MBZ (15 mg/kg/day) 10 days postinfection (dpi); G III: infected mice treated with NTZ (20 mg/kg/day) 10 dpi; G IV: infected mice treated with MBZ 60 dpi; G V: infected mice treated with NTZ 60 dpi; GVI: control group comprising uninfected mice. Mice were bled via retro-orbital plexus on four occasions between 30 and 120 dpi. Sera were processed using the ELISA technique to detect IgG anti- Toxocaraantibodies. At 120 dpi, mice were sacrificed for larval recovery in the CNS, liver, lungs, kidneys, eyes and carcass. Results showed similar levels of anti- ToxocaraIgG antibodies among mice infected but not submitted to treatment and groups treated with MBZ or NTZ, 10 and 60 dpi. Larval recovery showed similar values in groups treated with NTZ and MBZ 10 dpi. MBZ showed better efficacy 60 dpi, with a 72.6% reduction in the parasite load compared with NTZ, which showed only 46.5% reduction. We conclude that administration of these anthelmintics did not modify the humoral response in experimental infection by T. canis. No parasitological cure was observed with either drug; however, a greater reduction in parasite load was achieved following treatment with MBZ.

RESUMOFoi investigada a eficácia da nitazoxanida (NTZ) na toxocaríase murina experimental e os resultados comparados com os obtidos usando mebendazol (MBZ). Sessenta camundongos BALB/c machos, com idade entre seis e oito semanas foram divididos em grupos de 10 cada, 50 foram infectados oralmente com 300 ovos larvados de T. canise agrupados a seguir: GI: camundongos infectados não tratados; GII: camundongos infectados tratados com MBZ (15 mg/kg/dia) 10 dias pós-infecção (dpi); GIII: camundongos infectados tratados com NTZ (20 mg/kg/dia) 10 dpi, GIV: camundongos infectados tratados com MBZ 60 dpi; GV: camundongos infectados tratados com NTZ 60 dpi; GVI: controle não infectado. Os camundongos foram sangrados via plexo retro orbitário em quatro ocasiões entre o 30º e 120º dpi. Os soros foram processados pela técnica de ELISA para detecção de anticorpos IgG anti- Toxocara.Aos 120 dpi, os animais foram sacrificados para a recuperação larvária do SNC, fígado, pulmões, rins, olhos e carcaça. Os resultados mostraram níveis similares de anticorpos IgG anti- Toxocaraentre os camundongos infectados mas não submetidos a tratamento e os grupos infectados e tratados com MBZ ou NTZ, aos 10 e 60 dpi. Os valores da recuperação larval foram similares nos grupos tratados com NTZ e MBZ 10 dpi. MBZ mostrou melhor eficácia aos 60 dpi, com redução de 72,6% da carga parasitária comparada com NTZ, que mostrou redução somente de 46,5%. Concluímos que a administração destes anti-helmínticos não modificou a resposta humoral na infecção experimental por T. canis. Não foi observada cura parasitológica com nenhuma das drogas; porém maior redução na carga parasitária foi obtida após o tratamento com MBZ.

Molecular diagnosis of strongyloidiasis in tropical areas: a comparison of conventional and real-time polymerase chain reaction with parasitological methods.

This study aimed to evaluate the use of conventional polymerase chain reaction (cPCR) and real-time quantitative PCR (qPCR) in the diagnosis of human strongyloidiasis from stool samples in tropical areas. Stool samples were collected from individuals and were determined to be positive for Strongyloides stercoralis (group I), negative for S. stercoralis (group II) and positive for other enteroparasite species (group III). DNA specific to S. stercoralis was found in 76.7% of group I samples by cPCR and in 90% of group I samples by qPCR. The results show that molecular methods can be used as alternative tools for detecting S. stercoralis in human stool samples in tropical areas.

Immunofluorescence assay for diagnosis of strongyloidiasis in immunocompromised patients.

BACKGROUND: Strongyloides stercoralis is a parasite that causes human strongyloidiasis. The disease ranges from asymptomatic to severe forms, which are often fatal in immunocompromised individuals. Laboratory diagnosis is challenging owing to limitations in the use of conventional parasitological techniques. The present study aimed to evaluate the indirect immunofluorescence assay (IFA) using infective larvae of S. venezuelensis as an antigen for the immunodiagnosis of human strongyloidiasis in immunocompromised patients. METHODS: Serum and stool samples from 200 immunocompromised patients (HIV-positive, HTLV-1-positive, and renal, liver, and/or bone marrow transplantation candidates) were used. Stool samples were examined using three parasitological methods: Lutz, Rugai, and culture agar plate. IFA was performed using sections of infective larvae of S. venezuelensis as antigens, and showed 95.4% sensitivity and 95.8% and specificity. RESULTS: Among the 200 patients, 17 (8.5%) were positive for S. stercoralis by at least one parasitological method, and 43 (21.5%) were positive by IFA. CONCLUSIONS: IFA can be used as a screening method for the detection of S. stercoralis in immunocompromised patients.

Trichuris trichiura in a post-Colonial Brazilian mummy.

Trichuris trichiura is a soil-transmitted helminth which is prevalent in warm, moist, tropical and subtropical regions of the world with poor sanitation. Heavy whipworm can result either in Trichuris dysenteric syndrome - especially in children - or in a chronic colitis. In heavy infections, worms can spread proximally and may cause ileitis. Here we provide first microscopic evidence for a T. trichiura adult worm embedded in the rectum of a post-Colonial Brazilian adult mummy. During Colonial and post-Colonial times, many European chroniclers described a parasitic disease named Maculo whose symptomatology coincides with heavy helminthiasis. Based on our findings and on comparison of ancient textual evidence with modern description of heavy whipworm, we feel confident in considering that the two syndromes are expressions of the same pathological condition.