Identification of the zoonotic reservoir is important for leishmaniasis control program. A number of (wild) animal species may serve as reservoir hosts, including the opossum Didelphis marsupialis. A survey carried out in Didelphis specimens (n = 111) from the metropolitan region of Belo Horizonte, an important focus of human leishmaniasis in Brazil, is reported. All animals were serologically tested with indirect fluorescence antibody test (IFAT) and direct agglutination tests (DAT) based on L. (L.) donovani or L. (V.) braziliensis antigen. A sub-population (n = 20) was analyzed with polymerase chain reaction (PCR) for the presence of Leishmania-specific DNA. For species identification, PCR-positive samples were subjected to restriction enzyme fragment polymorphism (RFLP) analysis. Depending on the sero-diagnostic test employed, the sero-prevalence varied between 8.1% (9/111 animals positive with DAT test based on L. braziliensis antigen) and 21.6% (24/111 animals positive with IFAT). Five out of 20 samples analyzed with PCR tested positive for the presence of Leishmania-specific DNA. RFLP analysis revealed that two samples contained L. braziliensis complex DNA, one contained L. donovani complex DNA, and two samples could not be typed with the methodology used. These data suggest a potential role for the opossum as a reservoir host for zoonotic leishmaniasis in the region.

The direct agglutination test (DAT) based on a freeze-dried antigen and the rK39 dipstick test were evaluated for the sero-diagnosis of visceral leishmaniasis (VL). The sensitivity and specificity of both tests were determined using sera from confirmed VL patients (n = 21), healthy controls (n = 19) and from patients with other confirmed infectious diseases (n = 42). The DAT had a sensitivity and a specificity of 100%. The rK39 had a sensitivity of 85.7% and a specificity of 82%. Both tests were also used to screen blood samples of confirmed VL patients (n = 15) Visceral leishmaniasis (VL or kala-azar) is the most severe form of leishmaniasis. Approximately 500,000 new cases of human VL occur annually and the disease is mainly found in Brazil, East Africa and on the Indian subcontinent. American visceral leishmaniasis (AVL), caused by Leishmania chagasi, is a major health problem in many parts of Brazil. Traditionally, the disease was confined to rural and peri-urban areas, but in the last few years the number of human cases of AVL in metropolitan regions is dramatically increasing (Silva et al. 2001). It is important to diagnose AVL as early as possible, because the disease is in most cases fatal if left untreated. The principal clinical symptoms of AVL are an enlarged spleen and a prolonged irregular fever (WHO 1996). Other signs and symptoms are loss of weight, pallor, enlarged liver, enlarged lymph nodes, anaemia, cough and diarrhoea. These signs and symptoms may mimic those of malaria, typhoid, tuberculosis, schistosomiasis and other diseases. The clinical suspicion may be confirmed directly by the detection of parasites in patient material or by culture. However, sample retrieval is inconvenient for the patient and parasite isolation by culture is time-consuming, expensive and difficult.Because of the above-mentioned limitations of direct diagnostic methods, a number of indirect immunological tests have been developed. These tests should meet several prerequisites in order to be of practical use. They should be sensitive and specific, cheap (in particular for use in developing countries) and easy to perform under harsh field conditions (Veeken 1999). The direct agglutination test (DAT) remains the first line diagnostic tool in many developing countries as it is a simple test with a high sensitivity, specificity and reproducibility, easyto-perform and not requiring specialised equipment (Zijlstra et al. 1991, Boelaert et al. 1999a,b, Schallig et al. 2001. The introduction of a freeze-dried antigen makes the DAT very suitable for use under remote field conditions as a cold chain for storage of antigen is not required (Meredith et al. 1995, Zijlstra et al. 1997, Schallig et al. 2001. A limitation of the DAT is the relatively long incubation time (18 h) and the fact that serial dilutions of blood or serum must be made. A dipstick, rK39 dipstick, based on the cloned antigen of a 39 amino acid repeat that is part of a 230 kDa protein encoded by a kinesin-like gene of L. chagasi (Burns et al. 1993), may circu...

In recent years, considerable attention has been given to identify new antileishmanial products derived from medicinal plants, although, to date, no new effective compound has been recently applied to treat leishmaniasis. In the present study, the antileishmanial activity of a water extract from Zingiber officinalis Roscoe (ginger) was investigated and a purified fraction, named F10, was identified as responsible by this biological activity. The chemical characterization performed for this fraction showed that it is mainly composed by flavonoids and saponins. The water extract and the F10 fraction presented IC50 values of 125.5 and 49.8 μg/mL, respectively. Their selectivity indexes (SI) were calculated and values were seven and 40 times higher, respectively, in relation to the value found for amphotericin B, which was used as a control. Additional studies were performed to evaluate the toxicity of these compounds in human red blood cells, besides of the production of nitrite, as an indicator of nitric oxide (NO), in treated and infected macrophages. The results showed that both F10 fraction and water extract were not toxic to human cells, and they were able to stimulate the nitrite production, with values of 13.6 and 5.4 μM, respectively, suggesting that their biological activity could be due to macrophages activation via NO production. In conclusion, the present study shows that a purified fraction from ginger could be evaluated in future works as a therapeutic alternative, on its own or in association with other drugs, to treat disease caused by L. amazonensis.

Routinely, diagnostic and microbiology laboratories perform antibiogram analysis which can present some difficulties leading to misreadings and intra and inter-reader deviations. An Automatic Identification Algorithm (AIA) has been proposed as a solution to overcome some issues associated with the disc diffusion method, which is the main goal of this work. AIA allows automatic scanning of inhibition zones obtained by antibiograms. More than 60 environmental isolates were tested using susceptibility tests which were performed for 12 different antibiotics for a total of 756 readings. Plate images were acquired and classified as standard or oddity. The inhibition zones were measured using the AIA and results were compared with reference method (human reading), using weighted kappa index and statistical analysis to evaluate, respectively, inter-reader agreement and correlation between AIA-based and human-based reading. Agreements were observed in 88% cases and 89% of the tests showed no difference or a o4 mm difference between AIA and human analysis, exhibiting a correlation index of 0.85 for all images, 0.90 for standards and 0.80 for oddities with no significant difference between automatic and manual method. AIA resolved some reading problems such as overlapping inhibition zones, imperfect microorganism seeding, non-homogeneity of the circumference, partial action of the antimicrobial, and formation of a second halo of inhibition. Furthermore, AIA proved to overcome some of the limitations observed in other automatic methods. Therefore, AIA may be a practical tool for automated reading of antibiograms in diagnostic and microbiology laboratories.2