Carlos James Scaini

Human toxocariasis: current advances in diagnostics, treatment, and interventions

Toxocariasis is a neglected zoonosis caused by the nematodes Toxocara canis and Toxocara cati. This disease is widespread in many countries, reaching high prevalence independently of the economic conditions. However, the true number of cases of toxocariasis is likely to be underestimated owing to the lack of adequate surveillance programs. Although some diagnostic tests are available, their sensitivity and specificity need to be improved. In addition, treatment options for toxocariasis are limited and are non-specific. Toxocariasis is listed as one of the five most important neglected diseases by the CDC. This review presents recent advances related to the control of toxocariasis, including new immunodiagnostics, therapies, and drug formulations, as well as novel interventions using DNA vaccines, immunomodulators, and probiotics.

Presence of Toxocara canis eggs on the hair of dogs: A risk factor for Visceral Larva Migrans

The close contact between dogs and humans poses a high risk of exposure to Toxocara canis eggs, which can lead to Visceral Larva Migrans (VLM) syndrome. The objective of this study was to investigate the existence of these nematode eggs on the hair of the perianal region in stray and owned dogs. Samples of hair from 104 dogs of different ages were collected: 25 (24%) were positive for T. canis eggs, with mean of 614.8 eggs per gram of hair. Puppies were responsible for 99% of the total number of eggs. The ages of the animal and hair length were factors that influenced the intensity of the observed eggs. This study showed that dog hair contaminated by T. canis eggs in different developmental stages represents a potential source of VLM infection for humans.

Seroprevalence of Toxocara Infection in Children from Southern Brazil

Abstract: The seroprevalence of Toxocara canis antibodies in children aged from 1 to 12 yr old was evaluated in Pelotas City, Rio Grande do Sul, Brazil. Human toxocariasis or visceral larva migrans (VLM) was diagnosed with the use of an ELISA based on the T. canis excretory–secretory (TES) antigens; Western blotting was used to confirm the ELISA-positive results. From 427 samples, 50.6% were positive for the presence of anti-TES antibodies. A confirmatory test (Western blot) was carried out on a sample of the ELISA-positive sera (n = 70), and all were positive. The Western blots had specific banding pattern characteristics, where the 30-kDa fraction demonstrated the highest reactivity. This fraction could be important for the specific diagnosis of toxocariasis.

Contaminação ambiental por ovos e larvas de helmintos em fezes de cães na área central do Balneário Cassino, Rio Grande do Sul

In order to investigate the presence of helminthes agents of parasitic zoonoses, were examined 237 fecal samples of dogs from central area of the main beach of south coast of Rio Grande do Sul State. The eggs and larvae of genus Ancylostoma (71.3%) and Trichuris (32.5%) and Toxocara eggs (9.3%) were the most prevalent parasites detected.

Saccharomyces boulardii reduces infection intensity of mice with toxocariasis.

Several studies have shown the benefit of the use of probiotics in the prevention and treatment of diseases; however, few of them have investigated the effect of probiotics on parasitosis. In this study, the effect of Saccharomyces boulardii on the intensity of infection of mice with toxocariasis was evaluated. The animals were fed with a diet supplemented with S. boulardii for 15 days before inoculation with Toxocara canis eggs and for 2 or 60 days post-inoculation. S. boulardii promoted a reduction of approximately 36% in the average number of recovered T. canis larvae, suggesting that it can be used as an alternative to help control toxocariasis.

Activity of β-lapachone derivatives against rifampicin-susceptible and -resistant strains of Mycobacterium tuberculosis

The increase of incidence of tuberculosis (TB) with resistant strains and HIV co-infection has reinforced the necessity of developing new drugs for its treatment. The reaction of naphthoquinones with aromatic or aliphatic aldehydes in the presence of ammonium acetate led to the synthesis of the three β-lapachone derivatives (naphthoimidazoles) that were tested in this study. Phenazines were prepared by the reaction of the respective naphtoquinone with o-phenylenediamine in acetic acid under reflux. The antimicrobial activity of the derivatives was evaluated in vitro against Mycobacterium tuberculosis H37Rv (ATCC 27294) and the rifampicin-resistant strain (ATCC 35338) containing a His-526-Tir mutation in the rpoB gene. Using the Resazurin Microtiter Assay (REMA) method, bioactive molecules were observed in the susceptible and resistant strains with MICs ranging from 2.2 μM to 17 μM. The naphthoimidazoles with p-toluyl and indolyl group attached to the imidazole ring were more active against the H37Rv strain (MIC 9.12 μM and 4.2 μM, respectively) than the rifampicin-resistant strain (MIC 8.3 μM and 17 μM, respectively). The phenazine with the allyl-pyran group was most active among the two strains and had an MIC of 2.2 mM. These results show the potential of these molecules as prototypes for future drugs used in treating TB.

Comparative evaluation of the Nitrate Reductase Assay and the Resazurin Microtitre Assay for drug susceptibility testing of Mycobacterium tuberculosis against first line anti-tuberculosis drugs

Tuberculosis remains as a serious infection disease of worldwide distribution, with high morbidity and mortality, mainly in low socio-economic condition countries. The state of emergency of tuberculosis caused by the resistant and multidrug-resistant (MDR) strains, became the main threat to the tuberculosis treatment and control programs. A fast detection method for the resistant strains will allow the implementation of an adequate treatment and contribute for controlling the dissemination of these resistant strains. This study evaluated the performance of the nitrate reductase assay in solid (NRA-LJ) and liquid (NRA-7H9) media, to determine the susceptibility to first line anti-tuberculosis drugs: isoniazid (INH), rifampicin (RMP), ethambutol (EMB) and streptomycin (SMR). Both methods NRA-LJ and NRA-7H9 were evaluated among 18 strains with a known susceptibility profile. The resazurin microtiter assay (REMA) was performed as a reference method. One hundred percent of accordance was observed between NRA-7H9 and REMA for the four tested drugs. When the NRA-LJ method was compared to REMA, the sensitivity and the specificity to INH, RMP, EMB and SMR were 100%, 100 %, 85.7%, 76.9% and 80%, 100%, 75% and 80%, respectively. From the 57 clinical isolates of M. tuberculosis evaluated by NRA-7H9 and REMA, 56 (98.2%) were sensitive to all antibiotics tested (INH, RMP, EMB and SMR) by the NRA-7H9 method, while three of these strains were resistant to INH by REMA. One strain showed resistance to INH and RMP for both methods, and MIC of 1.0 μg/ml to INH for both methods, while MIC of 1.0 and 2.0 μg/ml to RMP for REMA and NRA-7H9, respectively. The three assays showed a high level of agreement for rapid detection of rifampicin and isoniazid resistance. Regarding rapidness, the detection of color change in the NRA method is within instants as compared to the overnight incubation required for the REMA test. NRA might represent an inexpensive and alternative assay for rapid detection of resistance in low-income countries.

Evaluation of diagnostic methods for the detection of Helicobacter pylori in gastric biopsy specimens of dyspeptic patients

Helicobacter pylori infects nearly 50% of the world’s population. This microorganism is accepted as the most important agent of gastritis and as a risk factor for peptic ulcer disease and gastric adenocarcinoma. Currently many diagnostic methods exist for detecting H. pylori, however they all have limitations, thus it is recommend a combination of at least two methods. The aim of this study was to evaluate diagnostic methods, such as in-house urease test, culture and Polymerase Chain Reaction (PCR), for the detection of the H. pylori in gastric biopsy specimens of 144 dyspeptic patients, using as gold standard the association between histology and rapid urease test. According to the gold standard used in this study, 48 (33.3%) patients were infected with H. pylori, while 96 (66.7%) were classified as not infected. The in-house urease test and the PCR were the most sensitive methods (100%), followed by culture (85.4%). However, the inhouse urease test and the culture were the most specific (100%), followed by PCR (75%). In conclusion, this study showed that, in comparison with the combination of histology and rapid urease test, the in-house urease test and the PCR presented 100% of sensitivity in the diagnosis of gastric infection by H. pylori, while the in-house urease test and the culture reached 100% of specificity. These finding suggest that the combination of two or more methods may improve the accuracy of the H. pylori detection.

Molecular Basis of Pathogenicity in Helicobacter pylori Clinical Isolates

ABSTRACT This study identified pathogenicity genes in 40 Helicobacter pylori clinical isolates. The cagA, vacA, and iceA genes were detected in 65%, 97.5%, and 97.5% of the isolates, respectively. The cagA, iceA1, and vacAs1a/m1 genes were related to erosive gastritis, whereas the vacAs2/m2 and iceA2 genes were associated with enanthematous gastritis.

Clonal diversity of M. tuberculosis isolated in a sea port city in Brazil

Genotyping tools have been widely used to study the occurrence of outbreaks and to identify the patterns of transmission of Mycobacterium tuberculosis strains. The clonal diversity of 65 clinical isolates of M. tuberculosis was determined by PCR methods. The Double Repeat Element method (DRE-PCR) and spoligotyping identified 45 and 26 distinct patterns respectively. Among these, LAM (38%) was the most frequent lineage, followed by Haarlem (31%) and T (20%). Five orphan patterns were not present in the SITVIT database. Mycobacterial interspersed repetitive units (MIRU) using 12 loci revealed 46 distinct patterns. MIRU loci 10, 23, 26 and 40 had the highest discriminatory power. The high genetic diversity found among M. tuberculosis isolates in this study suggests a high level of recent TB transmission, indicating an endemic mode of TB transmission and a putative importation of new TB genotypes. In addition, the high diversity among the isolates could indicate early detection of the infection in patients and an efficient rate of cure.