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Leishmaniasis in Sardinia. 5. Leishmanin reaction in the human population of a focus of low endemicity of canine leishmaniasis.

About half (640 subjects) of the population of Soleminis, a canine leishmaniasis focus 15 km north of Cagliari, Sardinia, was subjected to the leishmanin skin test. The total positive rate was 9.7%, and that of males was 15.5%. The age trend in the positive rate resembled a hyperbolic curve, with the 0-5 years age group rate being zero and the highest rate (39.3%) occurring in the 55-65 years age group. The Soleminis focus was classified as hypoendemic, with a prevalence of canine leishmaniasis of about 3%. Dog surveillance, land reclamation and changes in population habits during the last few decades are considered to be responsible for the reduction of transmission to man.

Adolescent↗

Leishmaniasis in Sudan. Post kala-azar dermal leishmaniasis.

Post kala-azar dermal leishmaniasis (PKDL) is increasingly recognized in Sudan as a complication of visceral leishmaniasis (VL), occurring in c. 55% of patients after, or during treatment of, VL. The development of PKDL seems to be restricted to parasites of the Leishmania donovani sensu stricto cluster; no particular zymodeme has been found to be associated with it. In contrast to PKDL in India, PKDL in Sudan occurs within 0-6 months after treatment for VL. The rash may be macular, maculo-papular or nodular, and spreads from the perioral area to other parts of the body, depending on grade of severity. Young children are particularly at risk of developing more severe disease. In 16% of PKDL patients, parasites can be demonstrated by microscopy in lymph node or bone marrow aspirates and, with the aid of the polymerase chain reaction (PCR), in lymph nodes of 81% of patients, possibly indicating persistent visceralized infection. Diagnosis can be made by demonstration of parasites in skin smears or biopsies in 20-30% of cases; newer techniques, using PCR with skin smears, have higher sensitivity (83%). Monoclonal antibodies against L. donovani can detect parasites in 88% of biopsies. Serological tests are of limited value. The leishmanin skin test is positive in 50-60% of cases; there is an inverse relationship between the skin test result and severity of PKDL. In differential diagnosis, miliaria rubra is the most common problem; differentiation from leprosy is the most difficult. In biopsies, hyperkeratosis, parakeratosis, acanthosis, follicular plugging and liquefaction degeneration of the basal layer may be found in the epidermis; in the dermis there are varying intensities of inflammation with scanty parasites and mainly lymphocytes; macrophages and epithelioid cells may also be found. In 20% of cases discrete granulomas may be found. After VL, the immune response shifts from a Th2-type to a mixed Th1/Th2-type. High levels of interleukin-10 in skin biopsies as well as in peripheral blood mononuclear cells and plasma in patients with VL predict the development of PKDL. Treatment is needed only for those who have severe and prolonged disease; sodium stibogluconate (20 mg/kg/d for 2 months) is usually sufficient. (Liposomal) amphotericin B is effective, whereas ketoconazole, terbinafine and itraconazole are not.

Age Distribution↗

Leishmaniasis in Greece I. Isolation and identification of the parasite causing human and canine visceral leishmaniasis.

Three human and 19 canine leishmanial stocks were typed according to their excreted factor serotype and the electrophoretic mobility of their MDH, GPI, G6PDH and 6PGDH and shown to be identical with regard to these characters and, thus with Leishmania donovani infantum. This verifies the opinion of earlier researchers, who suggested that the parasites which cause human and canine visceral leishmaniasis in Greece are the same organism and that dogs are the reservoir for the human infection. The complexities raised by the co-existence of human cutaneous leishmaniasis in Greece caused by L. tropica (formerly L. t. minor) are stressed. A comparison was made of the clinical symptomatology, serological diagnosis by IFA and ELISA tests and parasitological diagnosis of the human cases and canine infections.

Adult↗

Leishmaniasis in Greece II. Isolation and identification of the parasite causing cutaneous leishmaniasis in man.

The serological and biochemical identity of four Greek leishmanial strains isolated from cases of cutaneous leishmaniasis was determined. All four strains were identical and shown to be Leishmania tropica (formerly L. t. minor). The cases are described; two came from the Greek mainland and two from Greek islands, one of the latter being a case of leishmaniasis recidivans. The significance of the results is discussed, in particular the co-existence in Greece of strains of L. tropica and L. donovani infantum.

Adult↗

Leishmania aethiopica derived from diffuse leishmaniasis patients preferentially induce mRNA for interleukin-10 while those from localized leishmaniasis patients induce interferon-gamma.

Exposure of peripheral blood mononuclear cells to promastigotes of Leishmania aethiopica derived from patients with the self-limiting, localized form of the disease (local cutaneous leishmaniasis; LCL) preferentially induced mRNA for interferon (IFN)-gamma but little for interleukin (IL)-10. In contrast, stimulation of the same cells with promastigotes derived from patients with the persistent, disseminated form of the disease (diffuse cutaneous leishmaniasis; DCL) stimulated the expression of IL-10 rather than IFN-gamma. In general, parasites derived from LCL patients induced more expression of other cytokines tested, including IL-4, IL-6, and transforming growth factor-beta, although tumor necrosis factor-alpha was equivalent in cultures stimulated with LCL or DCL promastigotes. The results suggest that the antigen-specific immunosuppression observed in DCL patients and the resulting clinical picture could in part be due to the properties of the infecting parasite to induce more IL-10 than IFN-gamma.

Animals↗

Sero-epidemological survey on canine visceral leishmaniasis and the distribution of sandfly vectors in northwestern Turkey: prevention strategies for childhood visceral leishmaniasis.

Visceral leishmaniasis (VL) caused by Leishmania infantum, is an endemic disease in Aegean and Mediterranean Regions among humans and dogs. In this study, a sero-epidemiological survey for VL and cutaneous leishmaniasis (CL), which both are sporadically reported in the region, were carried out in the villages of Eskisehir, Afyon, and Bilecik cities. The study was designed according to the location of the sporadic cases of VL and CL, and blood samples of 111 dogs were randomly collected. Lymph node aspiration samples were taken from dogs that have popliteal lymphadenopathy. Sand flies were also collected using CDC light traps in the several localities. The sera samples were screened using IFAT, ELISA, rk39 ELISA and dip-stick tests for anti-Leishmania antibodies. A total of 15 (13.51 per cent) dogs out of 111 were found to be seropositive by at least one of the tests. The seropositivity ratios among dogs were found to be 27.5 per cent (8/29), 9.09 per cent (4/44) and 7.8 per cent (3/38) in Afyon, Bilecik and Eskisehir cities respectively. Leishmania amastigotes were detected in 4 of the 14 lymph node aspiration samples (eight seronegative, six seropositive), and all of them were seropositive dogs. One year later, two of the dogs were found to be dead and the other two were severely ill. Among the 179 collected Phlebotomus specimens from, Phlebotomus major was found to be abundant (35.7 per cent) and the other species were P. simici (28.5 per cent), P. similis (34.7 per cent) and P. alexandri (1.1 per cent). In the study area, canine VL is more spread than human VL. Because dogs are playing an important role for VL in Mediterranean Basin, and development of appropriate control measures will be necessary for childhood VL.

Animals↗

Leishmaniasis recidiva cutis in American cutaneous leishmaniasis.

BACKGROUND: Leishmaniasis recidiva cutis (LRC) consists of active lesions around or inside the scar of classical cutaneous leishmaniasis (CL). In the literature it is considered as an hyperergic form of CL because the patients show a strong response to intradermal testing with leishmania antigen and, histologically, the parasites are scarce or absent; a well-organized granuloma is always observed. METHODS: Three patients from Bahia (Brazil) with LRC were evaluated by clinical examination, biopsies, skin tests with leishmania antigen, serology, and culture. In addition, a specific lymphocyte blastogenesis test was done and the species of leishmania characterized. RESULTS: The disease was caused by both L. amazonensis and L. braziliensis and serological titers varied from 1/16 to 1/64. The patients presented histologic and immunologic aspects different from those referred to in the literature. From four biopsies obtained only two presented a granulomatous reaction and parasites varied from absent to a parasite index 3. In one patient an absence of T cell response to leishmania antigen was observed in the first evaluation with restoration of the response after cure. In the other two, the degree of the specific proliferative response was lower than that usually observed in patients with classical CL. CONCLUSIONS: These findings indicate that New World LRC can not be considered a hyperergic form of CL. With respect to its clinical aspects and response to treatment, LRC must be considered as an entity different from the classical CL.

Adult↗

Studies on the control of visceral leishmaniasis: validation of the Falcon assay screening test--enzyme-linked immunosorbent assay (FAST-ELISA) for field diagnosis of canine visceral leishmaniasis.

The Falcon assay screening test-enzyme-linked immunosorbent assay (FAST-ELISA), the latest version of the enzyme-linked immunosorbent assay, uses antigen-coated beads. A 96-well plate can be run in 20 min without electricity or expensive equipment. We compared the FAST-ELISA, a standard ELISA, and an indirect immunofluorescent assay (IFA) for evaluation of canine leishmaniasis under field conditions using samples from 161 dogs from our longitudinal study in the endemic area of Jacobina, Bahia, Brazil. Organisms were isolated by culture (NN medium) or by inoculation of hamsters with samples from 59 of the dogs. When plasma were tested, we found a sensitivity of 88% and a specificity of 90% using the FAST-ELISA with a spectrophotometer. Using the same plasma samples, the IFA had a sensitivity of 75% and a specificity of 93%. The standard ELISA had a sensitivity of 90% and a specificity of 85%. When whole blood was tested with the FAST-ELISA, we found a sensitivity of 85%. There was no significant difference between visual and spectrophotometric results with plasma or whole blood. The FAST-ELISA system provides a sensitive, specific, and field-adaptable test for canine visceral leishmaniasis, which can be evaluated quickly without the use of a microscope or spectrophotometer.

Animals↗

Transmission blocking vaccine studies in leishmaniasis: I. Lipophosphoglycan is a promising transmission blocking vaccine molecule against cutaneous leishmaniasis.

BACKGROUND: New strategies for control of leishmaniasis is needed as chemotherapy using antimonial drugs is prolonged, expensive, associated with side effects and relapses. Vector control has limitations and a vaccine which may be the best approach is not available. OBJECTIVES: To assess the level of inhibition of promastigote development and gut morphology in infected Phlebotomus duboscqi sandflies fed on different groups of BALB/c mice immunised with rgp63, lipophosglycan (LPG) or their cocktail and whole parasite antigens prepared from L. major culture-derived promastigotes. METHODS: BALB/c mice were immunised adequately with Leishmania major-derived antigens namely, crude whole parasite (WPA), recombinant 63 kilodalton glycoprotein (rgp63), LPG and a cocktail composed of rgp63 plus LPG antigens. Laboratory reared Phlebotomus duboscqi sandflies, the natural vector for L. major were later allowed to feed on immunised animals, interrupted and allowed to continue feeding on infected animals for an equal amount of time until they became fully engorged. The sandflies were maintained on apples as a carbohydrate source in an insectary maintained at a temperature of 25 degrees C and 80% relative humidity. Some of the sandflies were dissected on days 2, 4 and 6 after feeding and observed using the light and the transmission electron microscopy for any changes in their gut morphology. The remaining sandflies were all dissected on the sixth day post-feeding and examined for procyclics, nectomonads, haptomonads and metacyclic promastigote forms of Leishmania. RESULTS: Sandflies which had previously fed on WPA, LPG plus rgp63 cocktail and LPG-immunised mice showed the lowest infection rates compared to control sandflies fed on saline immunised mice (p < 0.05). A significant number of procyclic promastigotes, the first developmental form of the parasite in culture as well as in the sandfly was observed in sandflies which fed on LPG-immunised mice (p < 0.05). The dominant parasite form in sandflies which fed on rgp63 or LPG-immunised mice was the nectomonad form but very few of the infective metacyclic forms (p < 0.05). Control sandflies fed on saline immunised or infected mice alone displayed a normal pattern of parasite development up to the metacyclic stage. Studies showed that two possible mechanisms through which immune sera from immunised mice may cause inhibition of parasite development is by exflagellation of nectomonad forms and degeneration of the sandfly midgut epithelium as revealed by light and electron microscopy studies respectively. CONCLUSIONS: This study has shown that immune-mediated transmission blocking may be applied to Leishmania infections. Based on observation of the procyclic promastigotes, the dominance of the nectomonad forms, low infectivity rates in sandflies fed on LPG-immunised mice, we concluded that LPG stands out to be a promising transmission blocking vaccine candidate in leishmaniasis.

Animals↗

[Canine leishmaniasis. New concepts of epidemiology and immunopathology: their impact in the control of human visceral leishmaniasis].

Visceral leishmaniasis (VL) is a zoonosis in most regions where it occurs. Dogs are the most important reservoir of the disease and are mainly responsible for the persistence of VL in the Paleartic and Neotropical regions. Canine leishmaniasis (CaL) is a viscerocutaneous, chronic infection with a worse prognosis than human disease. We now know that, as in man, there are some cases of asymptomatic infection. Former studies indicated that dog cutaneous parasitism becomes infectious to the insect vector in later periods of the disease, but recent studies performed by xenodiagnosis have shown that it is possible that transmission might occur earlier. The infected animal reacts with a great production of antibodies and depression of cellular immunity. Antibodies are not protective and resistance is related with active cellular immunity. The presence of Th 1 response in asymptomatic animals, sometimes without humoral response, means that the prevalence of CaL, found in epidemiological surveys by searching for antibodies, may be underestimated.

Animals↗

[Epidemiology of leishmaniasis in Algeria. 6. Survey of clinical cases of infantile visceral leishmaniasis from 1965 to 1974].

The authors present the results of an inquiry conducted in the principal hospitals of Algeria. The number of cases of visceral leishmaniasis recorded over the last ten years (1965 to 1974) totaled 497. The disease occurs essentially in children under 5 years of age (94%); it is mainly detected in central and eastern parts of the Tell region: principally in the Grande Kabylie, Algerois and Constantinois areas (humid and sub-humid bioclimatic stages). The results of the malaria eradication campaign in relation to the incidence of visceral Leishmaniasis is discussed.

Age Factors↗

[Leishmaniasis in Bolivia. IV. The dog in the cycles of leishmaniasis in Bolivia].

In Bolivia, the dog is involved in the cycle of visceral leishmaniasis (Leishmania (Le.) chagasi) in the Yungas (alt. 1,000-2,000 m), and also in the cycle of cutaneous leishmaniasis (Le. (V.) braziliensis) in the Alto Beni (alt. 400-600 m). But it plays a different role in the two cycles. In the Yungas focus, it is the main reservoir of Le. (Le.) chagasi and the source of contamination for man. In the Alto Beni focus, it is only a "victim-host", like man, of Le. (V.) braziliensis; the reservoir of which is unknown. Wild mammals are very likely to be involved.

Animals↗

[American cutaneous and mucous leishmaniasis (mucocutaneous leishmaniasis)].

The American skin and mucous membrane leishmaniasis or mucocutaneous leishmaniasis is induced through phlebotomus bites and occurs in South and Central America. Untreated severe multilating ulcerations of the face with involvement of oral, nasal, and pharyngeal mucous membranes may occur. Therapy consists of intramuscular administration of three- or pentavalent antimon preparations. In failure-patients amphotericin B is used instead.

Amphotericin B↗

[Ecology of leishmaniasis in the south of France. 11. Canine leishmaniasis: successful experimental transmission from dog to dog by the bite of Phlebotomus ariasi Tonnoir, 1921 (author's transl)].

As part of a study of visceral leishmaniasis in the Cévennes in southern France, an infection was transmitted from dog to dog by the bite of a single sandfly, Phlebotomus ariasi Tonnoir, 1921. The role of this species as a vector, suspected from earlier studies, is, therefore, confirmed. Twenty female sandflies, which had engorged on a naturally infected dog 23 +/- 2 days previously were put with a healthy dog which, after an incubation period of 15 months, developed viscero-cutaneous leishmaniasis. In dissections of the sandflies immediately after contact with the experimental dog, it was found that only one had engorged. All of 17 sandflies dissected had midgut infections: 10 of these also had infections in the pharynx. The engorged specimen additionally had parasites in the proboscis, a condition thought by many workers to be necessary for the parasite to be transmitted by bite.

Animals↗

[Epidemiology of leishmaniasis in Algeria. 3. Systematic screening of cutaneous leishmaniasis in the Biskra area].

In the Biskra area which is a historical focus of cutaneous leishmaniasis, the authors have carried out a systematic survey of the disease among the school age population (age interval: 6-15 years of age). The incidence of the disease found through the detection of suspect cutaneous leishmaniasis scars rose to 32.4%. The incidence brought about by intradermal skin-testing (to Leishmanin) was 76.9%. The comparative value of the two systematic survey methods is discussed with reference to the situation of other endemic foci.

Adolescent↗

[Leishmaniasis in Ecuador. 1. Incidence of cutaneous leishmaniasis on the Pacific coast].

A clinico-epidemiologic survey on cutaneous leishmaniasis, due to Leishmania panamensis, was carried out on 961 persons in two study areas of the Pacific coast of Ecuador, to estimate the prevalence and the incidence of the disease. In the preandean hills, at Paraiso Escondido, the prevalence of active lesions was 4.8%; in the hills of the coastal cordillera, at La Tablada, it was 3.6%. The incidence of new cases in 1991 was high: 147% in the first village, and 106% in the second. These data are far higher than the Health Ministry statistics. The cumulated prevalence, obtained by addition of the scars and active lesions of leishmaniasis, was as high as 66% at Paraiso Escondido, and 47% at La Tablada. Most of the patients (62%) had only one ulcer or scar. Most of the people are contaminated during the first five years they live in these endemic areas. Nevertheless, the incidence remains high in all the age groups, because large numbers of migrants coming from non endemic regions are continuously settling in these colonization areas. Interviews have shown that the contaminations had occurred in the dry season, between July and December. These findings were confirmed by passive case detection at the Hospital A. Egas of Santo Domingo which covered the region. Contamination of young children and position of the lesions on the face suggested a domiciliary transmission, like in Panama and on the Pacific coast of Colombia.

Adult↗

Studies on Mediterranean leishmaniasis: V.A. preliminary epidemiological survey of human leishmaniasis in Tuscany.

Leishmanin skin testing was performed on 1,285 people in the Tuscany region of Italy. In a known endemic area for leishmaniasis there was an increasing positivity with age, while in another area the curve was bell-shaped suggesting an interruption of transmission in the recent past. In all areas the positivity rate for males was higher than for females, but it was not possible to distinguish between areas of cutaneous and visceral disease.

Age Factors↗