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Parasitología al día

versão impressa ISSN 0716-0720

Parasitol. día v.21 n.3-4 Santiago jul. 1997 






Leishmanin skin test (LST) was applied in 115 (40.5%) females and 169 (59.5%) males whoo suffered from cutaneous leishmaniosis(CL), with 1 to 7 cutaneous lesions, with > 2l1 days of evolution (mean = 47;DE = 36.7). Their ages ranged from 0 to 75 years (mean = 21). The clinical, parasitological, serological and immunological diagnosis of CL were studied. The LST reactivity was compared with respect to years age, sex, number and evolution of the lesion, before and after the treatment with glucantime (G)injected intramuscularly (IM). Second and third injections the G were necessary in 61.97% and 12.76% of thee patients respectively. The time required for healing ranged from 30 to 120 days. The diameter of the induration was of 5 to 27 mm before the treatment, and up to 27 mm of induration when no clinical manifestations were abserved in all cases of CL. A higher proportion of positive skin test was obtained in the > 8 years age group (79.22%) than in the younger group. The relatively higher prevalence of LST in children from 1 to 10 years correlates with the percentage distribution of positive parasitaemias, and is associated wih the male patients. These findings suggest that it is the intensity rather than the simple occurrence of parasitaemia which determine, the association into the LST and number and evolution of lesion in these cases of Cl. The frequency of LST positivity was higher in individual males (55.63%). When these infections were grouped according to years age, sex and time of infection, and relationship with LST, the differences were no longer significant.

Key words: Leishmaniosis, Cutaneous; Leishmanin, Skin; Test; Treatment; Glucantime.


*Investigaciones Parasitológicas «J.F. Torrealba», Departamento de Biología, Facultad de Ciencias, Universidad de los Andes, Mérida 5101, Venezuela.



The delayed-type hypersensitivity (DTH) or skin test of leishmanin (LST), frequently used for clinical diagnosis the CL, is a reaction of great value in epidemiological studies, an important recourse as implement to diagnose, it is the most important set of tools for immunity evaluation in Leishmania infections. Specific skin test reactivity has often been associated with acquisition of immunity to the reinfection and with cross reactivity.1 The skin test will become positive with the appearance of the cutaneous lesion and may remain positive forever, even after of the treatment, it indicates that a treated patient has developed cell-mediated immunity to Leishmania and so it should be regarded as favourable sign. The duration of LST reaction is widely considered to be lifelong.2 However, the duration of LST reactivity is best evaluated by following initially LST over time, monitoring the persistence of LST reactivity. The identified anti-Leishmania antibodies is a highly sensitive method for the diagnosis of CL and appears to be capable to distinguish past and current infections. The antibody titers started to decrease during the treatment and seronegative after the treatment with glucantine G when no clinical manifestations were observed,3 however, the skin test fails to distinguish between current and past leishmanial infection,4 the LST tested more than 10 years after healing of the leishmanial lesions showed positive reaction in 87% of the patients with CL.5 The present study was designed, therefore, to evaluate the usefulness of LST to confirm diagnosis of CL in an endemic area, in a large number of the cases of both sexes, with single or multiple lesion. The assay was also used to monitor improvement of disease, changing clinical status of the patients following treatment with G. The LST was done on each patient before and two months after the treatment with the antimonial, in order to measure the development of delayed hypersensitivity and to compare the variation of LST with years age, of patients sex and time of evolution of the cutaneous lesion.


Patients. The group of patient with cutaneous lesions, from 1 to 75 years age living in an endemic are for leishmaniosis in Merida state of Venezuela, with diagnosis clinical, parasitological by microscopic observation of macrophages containing amastigotes, in smears from the lesion on microscopic slides after Giemsa staining and serological assay antibodies anti-Leishmania positive for indirect immunofluoscence (IF)6 were diagnosed as positive for CL.3

Skin test (delayed-type hypersensitivity). The skin test was carried out on each patients before and after of the treatment with G. For the assay to LST, a dose of 0.1 ml of the antigen of L. mexicana to a concentration of 105 cell/mm, was injected intradermally on the inner surface to the left forearm. The diameter of the induration was measured 48 hrs. later, the larger diameter of the indurated area was considered positive because was bigger than 5 mm7.

Patients treatment. The patients undergoing treatment for injection IM of N-methyl glucamine (Glucantime® Specia, Paris, France) to reach a daily concentration of 60 mg of antimony/kg weight of body for 10 days each serie. The treatment was performed in three doses: 10 vaccine dose in patients with active cutaneous lesions (First vaccines dose), 15 days after the first vaccine dose (second dose), and 10 vaccine dose 40 days after of the second dose. The cure in patients was confirmed clinically with the complete reepithelialization of the lesion.

Statistical analysis. The result were expressed using the mean ± DE. The relationships into the LST were compared in the patient group with the age, sex and time of infection for chi-square test (X2)8. The significance level was of 0.05.


Treatment and LST. A total of 284 patients: 115(40.5%) females and 169 (59.5%) males between 1 to 7 cutaneous lesion of 30 to 211 days of evolution localized on their faces, hands, feet and other parts of the body, ranged from 1 to 75 years age (mean = 21.5 years), were diagnosis for Cl, by the recognition of amastigotes intro macrophages in smears of the cutaneous lesion, detection of antibody anti-Leishmania for IF assay and LST reactivity. The studied group received three vaccines of G. After the two course of G there was a marked clinical improvement in 61.97% of the cases. The distribution of patients for group age, sex and treatment with G are displayed in Table 1.

The patients showed a local reaction to LST antigens of 5 to 27 mm of induration (mean = 13.7l ± DE = 4.52). The group of children the 0 to 7 years age tested showed a positive skin test (mean = 12.1 ± DE = 4.22). The mean diameter of palpable induration in the group of > 8 years age was 13.7 mm ± DE = 4.52, and in the group to patient, with 8 to 75 years age (86.27%) the initial LST reaction showed an interval of diameter between 13 mm to 27 mm of induration. The higher LST reactivity was associated with the patients of > 21 years age in the 55.63% males and 36.60% in females (Table 2).

However, the difference the LST reaction was not significant when females and males the different years were compared. This difference was significant only in females and children (p < 0.05), but not in males, suggesting that children and women are exposed to the parasite in or around the houses, whereas adult males are, in addition, exposed elsewhere.


In this population with CL the size of the initial LST reaction was not statistically associated with the clinical characteristics of the disease after the treatment with G. When examined the relationship between the permanence of LST reactivity in both time of treatment with G, since healing and the time interval between the initially positive LST and a second skin test, loss of LST reactivity was not found However, were tested longer and permanence LST reactivity in the individuals had received antimonial treatment (Table 3). No significative differences between LST reaction and evolution of the lesion. The serologically monitored for determination of antibody anti-Leishmania, was positive with level up to 1:1024 and the antibody titer started to decrease and seronegative after the treatment con G.



Most of the studies on the immune response in patients with CL have been carried out measuring the LST reactivity, which produces different combination of the disease caused by Leishmania species, with different clinical conditions.9 Host characteristics also determine the sensitivity and potency of a given LST antigen, such as a lesion type (mucocutaneous and cutaneous), duration of active lesion, lesion stage (active vs healed) and time since healing.10-12 The duration of LST reaction is widely considered to be lifelong, this belief is based on observations that individuals with clinical histories consistent with having had leishmaniosis many years, in the past have been observed to remain LST reactive. However, the duration of LST reactivity is better evaluated by following initially LST-reactive individuals over time, monitoring the persistence of LST reactivity.13, 14 In this study, examined the relationship between permanence of LST reactivity in both time (active and healed), the initially positive LST and after of a second skin test in patients had received a antimonial treatment. The permanence of DHT in these cases may be due to continue exposure to Leishmania antigens either through latent infection or repeated biting by infected sand flies. In this study, the patients of 0 of 3 years (3.9%) was the group of children sedentary or in a short time exposed to the infection; the second group 3 to 7 years (9.8%), is a bit more exposed to the parasite cycle, because they are envolving in peridomestic tasks, while the third group 8 of 20 years (34.5%) and 21 years (51.8%), they are individuals who work in the field, for this reason, we suggesting that most adult could have been exposed to the infections. Other investigations, have been revelated the possibly the group with prevalence infections that included persons with a longer period of infection and with a more durable DTH response, the degree to which naturally acquired immunity confers lasting protection in subsequent infections.15

In this study, the percentage of positive LST reactions in CL is variable and the time of occurrence to the infections is independent of the sex and age of the patients. When the patients con CL were grouped according to similar ages and sex and compared with LST reactions before and after of treatment with G, were no longer significant.




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Corresponding author. Ana Lugo de Yarbuh
Mailing Address: Apartado 64, La Hechicera. Mérida 5101,
Fax (58-74)401286 or (58-74) 402418.
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