Drug and Alcohol Knowledge and Use Amongst Primary School Children (PDF 246 KB)

Mar-04

Leishmanial antigens in the diagnosis of active lesions and ancient scars of American tegumentary leishmaniasis patients

Cutaneous biopsies (n = 94) obtained from 88 patients with American tegumentary leishmaniasis were studied by conventional and immunohistochemical techniques. Specimens were distributed as active lesions of cutaneous leishmaniasis (n = 53) (Group I), cicatricial lesions of cutaneous leishmaniasis (n = 35) (Group II) and suggestive scars of healed mucosal leishmaniasis patients (n = 6) (Group III). In addition, active cutaneous lesions of other etiology (n = 24) (Group C1) and cutaneous scars not related to leishmaniasis (n = 10) (Group C2) were also included in the protocol. Amastigotes in Group I biopsies were detected by routine histopathological exam (30.2%), imprint (28.2%), culture (43.4%), immunofluorescence (41.4%) and immunoperoxidase (58.5%) techniques; and by the five methods together (79.3%). In Group II, 5.7% of cultures were positive. Leishmanial antigen was also seen in the cytoplasm of macrophages and giant cells (cellular pattern), vessel walls (vascular pattern) and dermal nerves (neural pattern). Positive reaction was detected in 49 (92.5%), 20 (57%) and 4 (67%) biopsies of Groups I, II and III, respectively. Antigen persistency in cicatricial tissue may be related to immunoprotection or, on the contrary, to the development of late lesions. We suggest that the cellular, vascular and neural patterns could be applied in the immunodiagnosis of active and cicatricial lesions in which leishmaniasis is suspected.

Distribution of sand flies (Diptera: Psychodidae) at different altitudes in an endemic region of American cutaneous leishmaniasis in the State of Espírito Santo, Brazil

The involvement of different sand fly species in the transmission of American cutaneous leishmaniasis (ACL) at different altitudes was evaluated in the municipality of Afonso Cláudio in the State of Espírito Santo, Brazil, from November 1995 to February 1997. CDC light traps and Shannon traps baited with human volunteers were hung simultaneously at three altitudes of a river valley: (a) 650-750 m in an area of active ACL transmission; (b) 750-850 m in a transitional area; and (c) 850-950 m in an area where no ACL transmission occurred. A total of 13,363 specimens belonging to 28 species was collected. The five most abundant man-biting species were Lutzomyia intermedia, which constituted 24.3% of the total, Lu. migonei (22.3%), Lu. whitmani (15.4%), Lu. fischeri (14.9%) and Lu. monticola (5.8%). Analysis of the distribution of these species at the three altitudes provided evidence that Lu. fischeri and Lu. monticola were not involved in ACL transmission, whereas Lu. migonei and Lu. whitmani might act as secondary vectors of Leishmania (Viannia) braziliensis and Lu. intermedia was probably the principal vector of the parasite. These results reinforce those published in the existing literature, which indicate that Lu. intermedia is the main vector of Le. (V.) braziliensis in Southeast Brazil, while Lu. migonei and Lu. whitmani are of secondary importance.

Leishmania cysteine proteinases: from gene to subunit vaccine.

Whole genome sequences of microbial pathogens present new opportunities for clinical application. Presently, genome sequencing of the human protozoan parasite Leishmania major is in progress. The driving forces behind the genome project are to identify genes with key cellular functions and new drug targets, to increase knowledge on mechanisms of drug resistance and to favor technology transfer to scientists from endemic countries. Sequencing of the genome is also aimed at the identification of genes that are expressed in the infectious stages of the parasite and in particular in the intracellular form of the parasite. Several protective antigens of Leishmania have been identified. In addition to these antigens, lysosomal cysteine proteinases (CPs) have been characterized in different strains of Leishmania and Trypanosoma, as new target molecules. Recently, we have isolated and characterized Type I (CPB) and Type II (CPA) cysteine proteinase encoding genes from L. major. The exact function of cysteine proteinases of Leishmania is not completely understood, although there are a few reports describing their role as virulence factors. One specific feature of CPB in Leishmania and other trypanosomatids, is the presence of a Cterminal extension (CTE) which is possibly indicative of conserved structure and function. Recently, we demonstrated that DNA immunization of genetically susceptible BALB / c mice, using a cocktail of CPB and CPA genes, induced long lasting protection against L. major infection. This review intends to give an overview of the current knowledge on genetic vaccination used against leishmaniasis and the importance of CP genes for such an approach.

IgG Anti-IgE Autoantibodies in Visceral Leishmaniasis

Procedures for IgG depletion in visceral leishmaniasis (VL) and schistosomiasis sera using Sepharose-protein G beads also deplete IgE. In this study, the presence of IgG anti-IgE autoantibodies in sera from patients with VL (n = 10), and hepatic-intestinal schistosomiasis (n = 10) and from healthy individuals (n = 10) was investigated. A sandwich ELISA using goat IgG anti-human IgE to capture serum IgE and goat anti-human IgG peroxidase conjugate to demonstrate the binding of IgG to the IgE captured was performed. VL sera had higher titers (p < 0.05) of IgG anti-IgE autoantibodies (OD = 2.01 ± 0.43) than sera from healthy individuals (OD = 1.35 ± 0.16) or persons infected with Schistosoma mansoni (OD = 1.34 ± 0.18). The immunoblotting carried out with eluates from Sepharose-protein G beads used to deplete IgG from these sera and goat anti-human IgE peroxidase conjugate, showed a similar pattern of bands, predominating the 75 kDa epsilon-heavy chain and also polypeptides resulting from physiological enzymatic digestion of IgE. A frequent additional band immediately above 75 kDa was observed only in VL sera.

Ecological Aspects of Phebotomine (Diptera, Psychodidae) in an Endemic Area of Tegumentary Leishmaniasis in the Northeastern Argentina, 1993-1998

The first epidemic tegumentary leishmaniasis´ outbreak in the province of Misiones was recorded in 1998, in the locality of Puerto Esperanza. Phlebotominae collected in the region, previously or simultaneously to the outbreak (September 1993-December 1998) showed that the species Lutzomyia intermedia s. l. was prevalent (94%, n 6,150) at all the sites sampled with miniature light trap (10) and Shannon trap (3). L. pessoai, L. whitmani, L. migonei, L. shannoni, L. fischeri, L. misionensis, Brumptomyia avellari and B. guimaraesi were also captured. Sand fly distribution in time and space suggests that in the province of Misiones (1) the species already present before 1990 could give rise to the epidemic by the density/dispersion fluctuation of their local populations; (2) the abundance of L. intermedia s. l. was associated with environments with ecotones of primary-secondary vegetation, close to water bodies and with moderate human disturbance; (3) this species showed, towards the end of 1997, peaks of exceptional abundance, subsequent to rainfall peaks in 1996. This increase in abundance of potential vector sand fly populations close to houses with colonizable surroundings could have generated the 1998 epidemic outbreak.

Muco-cutaneous leishmaniasis in the New World: The ultimate subversion.

Infection by the human protozoan parasite Leishmania can lead, depending primarily on the parasite species, to either cutaneous or mucocutaneous lesions, or fatal generalized visceral infection. In the New World, Leishmania (Viannia) species can cause mucocutaneous leishmaniasis (MCL). Clinical MCL involves a strong hyper-inflammatory response and parasitic dissemination (metastasis) from a primary lesion to distant sites, leading to destructive metastatic secondary lesions especially in the nasopharyngal areas. Recently, we reported that metastasizing, but not non-metastatic strains of Leishmania (Viannia) guyanensis, have high burden of a non-segmented dsRNA virus, Leishmania RNA Virus (LRV). Viral dsRNA is sensed by the host Toll-like Receptor 3 (TLR3) thereby inducing a pro-inflammatory response and exacerbating the disease. The presence of LRV in Leishmania opens new perspectives not only in basic understanding of the intimate relation between the parasite and LRV, but also in understanding the importance of the inflammatory response in MCL patients.

Presence of American cutaneous leishmaniasis vectors surrounding the city of Medellín, Colombia

The presence of Lutzomyia (Helcocyrtomyia) hartmanni, as a vector of Leishmania colombiensis and L. columbiana (Verrucarum group), recently incriminated in the transmission of leishmaniasis, and L. pia (Verrucarum group) are reported for the first time in a periurban area of Medellín city. There is thus a risk of leishmaniasis transmission in this town.

Phlebotomine sand flies (Diptera: Psychodidae) associated with the appearance of urban leishmaniasis in the city of Sincelejo, Colombia

Although once associated only with rural areas, the American leishmaniasis vectors now appear to be associated also with urban and suburban areas of the Neotropics. Following the appearance of the first autochthonous visceral and cutaneous leishmaniasis cases in the urban area of the city of Sincelejo, Colombia, a preliminary entomological survey of the sand fly species composition was performed using Shannon and CDC light traps. A total of 486 sand flies representing six Lutzomyia species were collected. L. evansi, L. panamensis and L. gomezi, known vectors of Leishmania spp. were the predominant sand fly species around dwellings. The finding of these species in relation to the appearance of the first cases of leishmaniasis in the city mentioned is discussed.

Seasonality of Lutzomyia intermedia and Lutzomyia whitmani (Diptera: Psychodidae: Phlebotominae), occurring sympatrically in area of cutaneous leishmaniasis in the State of Rio de Janeiro, Brazil

Lutzomyia intermedia and Lutzomyia whitmani occur sympatrically in the district of Posse, municipality of Petrópolis, in the State of Rio de Janeiro (114 km from the city of Rio de Janeiro), where sand flies were captured weekly for three consecutive years in both the peridomicile and forest, in two first years from 18:00 to 22:00 h, using a Shannon trap and CDC light traps. The anthropophilic habit was assessed by recording the specimens that bit the human captors. Considering the different capture types and sites, the following species were identified: Brumptomyia brumpti, B. cardosoi, B. guimaraesi, Lutzomyia amarali, L. longipalpis, L. microps, L. costalimai, L. edwardsi, L. firmatoi, L. migonei, L. termitophila, L. tupynambai, L. fischeri, L. pessoai, L. lutziana, L. shannoni, L. barrettoi, L. intermedia, L. whitmani, L. lloydi, and L. minasensis. L. intermedia (38.3%) and L. whitmani (38.6%) predominated. L. intermedia predominated in the peridomicile, where it displayed more intense anthropophily, while L. whitmani displayed greater density in the banana plantations and forest, preferential sites for biting humans. Studies on seasonality showed that while L. intermedia displayed greater density in the hottest months of the year (December, January, and February), L. whitmani was abundant in the coolest months (June, July, and August), although both occurred throughout the year.

Making Knowledge Work for Health: A Strategy for Health Research

Making Knowledge Work for Health: A Strategy for Health Research, provides a framework for the development of health research to enhance health and quality of life and help ensure that our research compares favourably with the rest of the world. I believe that an active research community working close to the delivery of health care in clinical settings, laboratories, the community, third-level institutions and the healthcare industry is critical to the improvement of the quality of health services generally. It is vital for professional development and career satisfaction of health service staff. It is also important for the translation of ideas into medical and IT products that can add value to our economy Download the Report here

Evaluation of the direct agglutination test and the rK39 dipstick test for the sero-diagnosis of visceral leishmaniasis

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) and serum samples of VL suspects (n = 61). The DAT found all blood samples of confirmed VL patients positive and tested 98.4% of the serum samples of the VL suspects positive. In contrast, rK39 detected in 9/15 blood samples (60%) antibodies against Leishmania chagasi and found 85.3% of the serum samples of the suspected patients positive. Although the rK39 dipstick is more rapid and user friendlier than the DAT, the latter has a superior sensitivity and specificity. Furthermore, the reagents used for DAT do not require cold storage, whereas the buffer of the rK39 must be stored at 4ºC. Therefore, the DAT is the most suitable test for the sero-diagnosis of VL under field conditions.

Epidemiological and immunological aspects of human visceral leishmaniasis on Margarita Island, Venezuela

Sixty-five patients were diagnosed with visceral leishmaniasis (VL) on Margarita Island in the decade from 1990 to1999; 86.2% were <= 3 years old. All were leishmanin-negative at diagnosis. Evaluation of 23 cured patients in 1999 revealed that 22/23 had converted to leishmanin-positive; five had persisting antibodies to rK39 antigen, with no clinical evidence of disease. Leishmanin tests were positive in 20.2% of 1,643 healthy individuals from 417 households in endemic areas. Of the positive reactors, 39.8% were identified in 35 (8.4%) of the households, 15 of which had an antecedent case of VL, a serologically positive dog or both. Weak serological activity to rK39 antigen was detected in 3 of 488 human sera from the endemic areas. The presence of micro-foci of intense peri-urban transmission and the apparent absence of other Trypanosomatidae causing human disease offer a unique opportunity for the study of reservoirs, alternative vectors and evaluation of control measures on the Island.