Epidemiological aspects of American Cutaneous Leishmaniasis in a periurban area of the metropolitan region of Belo Horizonte, Minas Gerais, Brazil

In order to characterize the epidemiology of American Cutaneous Leishmaniasis (ACL) in a periurban area of the municipality of Sabará in the metropolitan region of Belo Horizonte (MRBH), an area until then considered free of the disease, a cross sectional survey was undertaken in 1990. The survey of the population consisted of 1119 interviews and 881 clinical examinations using Montenegro's skin test (MST). A low prevalence (3.7%) of positive MST was encountered. The disease had been occuring in the area for about 20 years in the form of sporadic cases. The predominant species of sandfly both in domestic areas and nearby areas of secondary vegetation was Lutzomyia whitmani. A canine survey of delayed hypersensitivity to the antigen P10,000 identified only one dog with a positive reaction out of 113 examined. The transmission of ACL in MRBH was confirmed. The occurrence of the disease in women, children and individuals with no contact with forest areas as well as the presence of potential vector species in the domiciliar environment, suggests the transmission of the disease in this environment.

The subclinical form of experimental visceral leishmaniasis in dogs

Pathological aspects of a subclinical form of experimental canine leishmaniasis is reported here for the first time. Fifteen mongrel dogs were used in the present study. Eight dogs were infected and seven were used as control. Four of the control dogs were inoculated with spleen cells from non-infected hamsters. The eight mongrel dogs inoculated intravenously with amastigotes forms of Leishmania chagasi envolved for periods as long as 25 months without any clinical characteristic sign of classical Visceral Leishmaniasis (VL). Most of the laboratory test results were compatible to those of the seven control animals but culture of bone marrow aspirated material and serologic testing (IIF) demonstrated or provided evidence that the animals were infected. The most important and predominant histopathological lesion in infected animals were epitheloid granulomas presented in the liver, spleen, adrenal gland and lung of some animals. Channels containing erythrocytes in some granulomas of the liver suggeste that these granulomas are formed inside sinusoidal capillaries. Despite the animals were proved to be infected and presented characteristic histologic lesions, they did not present external signs of disease. The granulomatous aspect of the lesions indicates a good immunologic reactivity and suggest that a host-parasite equilibrium does exist in the dog experimental model

Resistance to oxidative stress is associated with metastasis in mucocutaneous leishmaniasis.

Mucocutaneous leishmaniasis (MCL) in South and Central America is characterized by the dissemination (metastasis) of Leishmania Viannia subgenus parasites from a cutaneous lesion to nasopharyngeal tissues. Little is known about the pathogenesis of MCL, especially with regard to the virulence of the parasites and the process of metastatic dissemination. We previously examined the functional relationship between cytoplasmic peroxiredoxin and metastatic phenotype using highly, infrequently, and nonmetastatic clones isolated from an L. (V.) guyanensis strain previously shown to be highly metastatic in golden hamsters. Distinct forms of cytoplasmic peroxiredoxin were identified and found to be associated with the metastatic phenotype. We report here that peroxidase activity in the presence of hydrogen peroxide and infectivity differs between metastatic and nonmetastatic L. (V.) guyanensis clones. After hydrogen peroxide treatment or heat shock, peroxiredoxin was detected preferentially as dimers in metastatic L. (V.) guyanensis clones and in L. (V.) panamensis strains from patients with MCL, compared with nonmetastatic parasites. These data provide evidence that resistance to the first microbicidal response of the host cell by Leishmania promastigotes is linked to peroxiredoxin conformation and may be relevant to intracellular survival and persistence, which are prerequisites for the development of metastatic disease.

Visceral leishmaniasis in Teresina, state of Piauí, Brazil: preliminary observations on the detection and transmissibility of canine and sandfly infections

A Leishmania donovani-complex specific DNA probe was usedto confirm the widespread dissemination of amastigotes in apparently normal skinof dogs with canine visceral leishmaniasis. When Lutzomyia longipalpis were fed on abnormal skin of five naturally infected dogs 57 of 163 (35 per cent) fliesbecame infected: four of 65 flies (6 per cent) became infected when fed on apparently normal skin. The bite of a single sandfly that had fed seven days previouslyon a naturally infected dog transmitted the infection to a young dog from a non-endemic area. Within 22 days a lesion had developed at the site of the infectivebite (inner ear): 98 days after infection organisms had not disseminated throughout the skin, bone marrow, spleen or liver and the animal was still serologically negative by indirect immunofluorescence and dot-enzyme-linked immunosorbent assay. When fed Lu. longipalpis were captured from a kennel with a sick dog known to be infected, 33 out of 49 (67 per cent) of flies contained promastigotes. In contrast only two infections were detected among more than 200 sandflies captured in houses. These observations confirm the ease of transmissibility of L.chagasi from dog to sandfly to dog in Teresina. It is likely that canine VL is the major source of human VL by the transmission route dog-sandfly-human. the Lmet2 DNA probe was a useful epidemiological tool for detecting L. chagasi in sandflies.

Endemic leishmaniasis in Brazil: future implications

Some predictions are made as to how work on leishmaniaisis and its control will develop in Brazil in the future.

Ecoepidemiological aspects of american cutaneous leishmaniasis in the state of São Paulo, Brazil

The aim of this study is to review some of the ecoepidemiological aspects of american cutaneous leishmaniasis (ACL) in the state of São Paulo, Brazil. During the first half of this century ACL occured in São Paulo, predominantly on the bank of the Tietê river, where there were railroad constructions and there was inevitable contact between and forested areas. Man's activities resulted in a drastic reduction of the forested regions of the state and molded the present landscape found in São Paulo, which brought a gradual change in the epidemiology of ACL during this century. Currently ACL can be considered as an endemic disease. Nowadays, ACL is found in different regions of São Paulo state, and is no longer limited to the bank of the Tietê river. The disease occurs in all age groups and sexes. Lack of knowledge about wild reservoir hosts of Leishmania (V.) braziliensis has simulated speculation about the possible role played by domestic animals (dogs and equines). Man's activities also favoured Lutzomyia intermedia a sandfly species which can clearly thrive in changed environments L. (V.) braziliensis continues to be transmitted, even after decades of forest destruction in São Paulo.

American cutaneous leishmaniasis in Pernambuco, Brazil: eco-epidemiological aspects in "Zona da Mata" region

American cutaneous leishmaniasis (ACL) has been increasing in Pernambuco, thus becoming an important problem for Public Health. The incindence is predominant in the region called "Zona da Mata", in the east of this state. This region corresponds geographically to the primitive area of the Atlantic forest. In order to characterize the eco-epidemiology expression of ACL in this region, two localities situated in the municipalities of Amaraji e Cortes have been selected by the criterion of higher incindence of human cases. Five stocks of patients were characterized and identified on the basis of enzyme profiles as a new variant of Leishmania (V.) braziliensis. A survey of wild and domestic animals was carried out by means of a parasitological and serological diagnosis. Through the analysis of the spleen and liver imprints, were detected amastigotes compatible with Leishmania in five Nectomys s. squamipes, five Bolomys l. pixuna, two Rattus r. alexandrinus and one Rattus r. frugivorus. For two years we carried out monthly sandflies captures using CDC light traps as well as manual captures. Lutzomyia whitmani was predominant, which accounted for 97.4 por cento of the total. These data indicate a strong evidence on the vector and the potential reservoirs of L. braziliensis in this region.

Vectors control importance on leishmaniasis transmission

We reviewed the control of transmission of leishmaniasis regarding chemotherapy, reservoirs elimination, vaccination and insect control through the use of chemical insecticides. We also discussed complementary measures like monitoring traps, impregnated bednets and curtains, repelents, pheromones, biological control, etc. A cost comparison of insecticide interventions through the use of products belonging to the four main chemical groups was also alone, comparing together conventional formulations versus a slow-release insecticide developed by the Núcleo de Pesquisas de Produtos Naturais, Universidade Federal do Rio de Janeiro. We finally did recommendations on the situation that would justify an insecticide intervention to control sandflies.

Exploitation of parasite derived antigen in therapeutic success of human cutaneous leishmaniasis in Brazil

In a complete study in 25 patients with American cutaneous leishmaniasis, caused by Leishmania braziliensis complex, immunotherapeutic efficacy of parasite derived antigen (94-67 KD) has been compared to antimonial therapy. Additionally, to delineate the mechanism of therapeutic success, microscopical features of immune response in active lesions and healed or non-healed lesions following therapy were analyzed. The results showed that cure rates in immunotherapy and chemoterapy were equal (>83 por cento). The immunohistochemical changes in two therapeutic groups were also largely similar. The analysis of humoral and cellular immune response suggest that appropriate stimulation of T helper cells in the lesion site, in association with one or more cytokines, play a key role in the healing process.

The brazilian leishmaniasis control program

The control methods used in Brazil for both cutaneous and visceral leishmaniasis by the Ministry of Health's National Health Foundation (Fundação Nacional de Saúde) are presented. Data referring to the programme between 1980 and 1991 is presented. There was an increase in the total number of notified cases of cutaneous leishmaniasis until 1987 and from this date onwards the number has remained between 23,000 and 26,000 per year. There were significantly fewer cases of visceral leishmaniasis during the same period and until 1991 the greatest number of cases reported in one year was 2,511 in 1985. The overall picture is that it is difficult to evaluate to what extent the control methods employed have reduced the number of cases of either form of the disease. It is suggested that there is an urgent need for a closer approximation of research and health workers to review the actual control strategies and to define procedures capable of assessing accurately their impact.