Leishmanaisis

Leishmanaisis

Date: 
01/07/2000
Investigation Line: 

Abstract

The objective of the present study is to describe two cases of dogs with mucocutaneous lesions caused by Leishmania spp. Both dogs presented destruction of the nasal septum, hyperemia with soft palate edema and barking alteration due to laryngeal compromise. Biopsies were taken from the lesion border and Leishmania spp. amastigotes were seen in the imprints. The dogs presented positive serology when complex soluble antigen from Leishmania mexicana was used. One of the dogs was also suspected to be infected by Trypanosoma cruzi as suggested by its positive reaction with a purified specific antigen, Ag163B6-cruzipain. Most of the studies concerning leishmaniosis in dogs have described the cutaneous form of this disease in close association with human cases of Leishmania infection instead of the mucocutaneous form described herein. The presence of dogs with mucocutaneous leishmaniosis alerts on an increase of the prevalence of this form in humans, which can cause deforming lesions, alterations of the speech and even an inadequate nutrition due to difficulties in deglutition.

Date: 
30/04/1999
Investigation Line: 

Abstract

The existence of patients suffering a double infection caused by Trypanosoma cruzi and Leishmania spp. has been suggested by several authors. Since the conventional serological tests now available for the diagnosis of Chagas' disease lack specificity due to the cross-reactivity between these two parasites, a serological confirmation of a T. cruzi infection cannot be made unless specific antigens are used. An enzyme linked immunosorbent assay (ELISA) to detect antibodies against a specific T. cruzi antigen, named Ag163B6, and immunoblotting using T. cruzi epimastigotes, are non-conventional serological techniques that could be employed for specific diagnosis of Chagas' disease. Using these two methods 34 cutaneous or mucocutaneous leishmaniasis patients were classified into two groups: (A) patients with serological evidence of T. cruzi infection, i.e. those who tested positive in at least one assay (18/34); and (B) patients with no serological evidence of T. cruzi infection, i.e. those who were negative for both assays (16/34). Taking into account the difficulties of xenodiagnosis and its low sensitivity (less than 50%) for a direct diagnosis in the chronic period of the disease, we used polymerase chain reaction (PCR) to confirm a T. cruzi infection in those leishmaniasis patients who presented positive results with the non-conventional serological techniques. Of the 18 patients with serological evidence of T. cruzi infection, 17 gave positive results when genomic DNA primers were used. Using minicircle primers, 15/18 of that group were positive. Nevertheless, all the patients suspected of being double infected were positive in at least one PCR test. Just one patient with no serological evidence of T. cruzi infection gave a positive PCR result when amplifying the minicircle sequence. The proof of the existence of a T. cruzi infection by PCR in leishmaniasis patients suspected to be chagasic when non-conventional serology was used, strongly supports the use of the specific Ag163B6 and immunoblotting with epimastigotes as specific serological diagnostic tools to determine a T. cruzi infection.

Date: 
03/01/1996
Investigation Line: 

Abstract

The occurrence of leishmaniasis patients carrying a double infection with Trypanosoma cruzi has been suspected but not proved. In this study, we analyzed sera of leishmaniasis patients from a region endemic for both parasites by using immunoblotting with epimastigotes and a purified antigen specific for T. cruzi (Ag 163B6). Seven of 12 patients showed a pattern of bands characteristic of chagasic patients reacting with antigens with molecular weights of 131, 125, 116, 111, 51-45, and 43 kD, and positive reactivity with Ag 163B6. Xenodiagnosis for T. cruzi was carried out in all patients; this technique has a positivity rate of 50% in chronic chagasic patients. The presence of T. cruzi trypomastigotes was shown in the blood of three, thus confirming the existence of a double infection in humans. Since the two parasites possess cross-reacting antigens, it may be assumed that previous infection with one of the parasites may affect the course of subsequent infection with the other. Nevertheless, T. cruzi infection did not prevent the appearance of typical leishmaniasis lesions. Therefore, antigenic cross-reactivity is unable to induce a sterilizing immune response against Leishmania.

Date: 
01/01/1996
Investigation Line: 

Abstract

In many regions of South America there are overlapping endemic areas for American Trypanosomiasis (Chagas' disease) and Leishmaniasis. T. cruzi and Leishmania spp, the causative agents of these parasitoses belong to the Trypanosomatidae family and share various antigens that cause cross-reactivity in serological diagnosis when complex antigenic mixtures are used. We studied patients who sought medical attention because of cutaneous or mucocutaneous lesions typical of leishmaniasis infection. These patients were from the province of Salta where Trypanosomiasis and Leishmaniasis are endemic diseases. Sixty-two patients gave a positive Montenegro skin test and, of these, 53 (85, 48%) showed the presence of amastigotes in Giemsa stained smears of dermal scrapings. Seven patients were not included because they were negative for both assays. We analyzed the leishmaniasic sera against homologous antigens to study the immune response and against complex heterologous antigens from T. cruzi to evaluate cross-reactivity phenomena. We also tested these sera against specific antigens for diagnosis of Chagas' disease in order to search for mixed infections. When complex antigens from leishmania were used, the sera showed an unusually strong antibody response 100% positive by IFA, 88.7% by ELISA and 80.6% by immunoblotting. Furthermore, significant cross-reactivity was found when conventional antigens for the serodiagnosis of Chagas' disease were used: 74.19% by IHA, 91.93% by IFA, and 76.80% by ELISA. We have previously purified by immunoaffinity, using a monoclonal antibody, an antigen termed Ag163B6 which is not present in L. mexicana. This antigen has shown the ability to specifically differentiate sera of chronic chagasic patients from those of leishmaniasic patients in ELISA. Furthermore, recent studies from our laboratory by immunoblotting, have demonstrated that chronic chagasic patients exhibit a specific reactivity pattern against T. cruzi epimastigotes that can be distinguished from those presented by leishmaniasic patients in spite of cross-reactive antigens. According to the results obtained in these assays, we classified the patients in two groups: 1) Patients with evidence of T. cruzi infection, those who tested positive in at least one assay: 2) Patients with no evidence of T. cruzi infection who were negative for both assays. More than 50% (32/62) of the patients showed strong evidence of mixed infection with T. cruzi. On the other hand, high cross-reactivity between these two parasitoses was shown in the second group without any evidence of T. cruzi infection since 18 out of 30 were positive in at least two conventional serological reactions. This implies that they would be misdiagnosed as chagasics if conventional reactions were used. These results emphasize the importance of the use of defined antigens and appropriate techniques for the differential diagnosis of these parasitoses, which is more important in areas endemic for both of them.

Date: 
01/01/1994
Investigation Line: 

Abstract

In an open trial, longer courses of pentavalent antimonials (Sbv) at sub-optimal doses (10 mg/kg body weight), in association with recombinant human interferon-gamma (IFN-gamma) (100 micrograms/m2 of body surface area) were administered, by daily intramuscular injections, to 13 patients with diagnoses of cutaneous or mucocutaneous leishmaniasis unresponsive to Sbv. Four patients presented with large skin ulcers, and 9 had mucosal involvement as the main manifestation, the latter affecting the nose (3 cases), nose and septum (2 cases), nose and oral cavity (1 case), and nose, pharynx and larynx (3 cases). Except for one case with severe involvement of the upper respiratory tract, the lesions were fully resolved by the end of therapy (mean duration 40 +/- 12 [SD] d, range 30-60 d) in the 11 patients who completed therapy. The main side effects were headache and fever (7 cases), together with leucopenia and eosinophilia (4 cases). It is concluded that combined administration of low doses of Sbv plus IFN-gamma may provide a novel therapeutic approach for the treatment of antimony-resistant cutaneous or mucocutaneous leishmaniasis. The possible mechanisms by which IFN-gamma contributes to resolution of the disease are discussed.

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