Assessing reservoir host status in leishmaniasis with special reference to the infectiousness of Leishmania (Viannia) braziliensis infections in wild rodents

ABSTRACT Molecular methods have been responsible for a notable increase in the detection of Leishmaniinae infections in wild animals. Determining their infectiousness is of paramount importance in evaluating their epidemiological significance. One of the most efficient ways of determining infectiousness for vector borne diseases is xenodiagnosis with the appropriate vector. However, this is logistically very difficult to accomplish in the field, and an ideal solution is to find a molecular surrogate for xenodiagnosis. In this review we discuss different approaches to the problem by focusing on the infectiousness of Leishmania (Viannia) braziliensis in rodents under laboratory and field conditions. Comparisons with similar studies for other Leishmania species emphasizes that there are pivotal differences in the infectiousness and the importance of asymptomatic infections in different hosts. Potentially the most promising surrogate is the real time quantitative PCR (qPCR). However, its success depends on choosing a tissue that relates to the vector's feeding location and the parasite's tissue tropism. This requires detailed knowledge of the infection of each species in its wild hosts. We conclude that for L. (V.) braziliensis infections in wild rodents the tissue of choice for a molecular xenodiagnostic test, based on the qPCR is blood, providing that a significant number of samples must be examined.

Should reproductively isolated populations of Lutzomyia longipalpis sensu lato receive taxonomically valid names?

A group of 18 research workers involved in different aspects of the biology of Lutzomyia longipalpis discussed whether or not it is important to give taxonomically valid names to populations that have been defined by biological, biochemical and molecular methods to be reproductively isolated. The type material of this medically important species has been lost and because of this it was recommended that a colony should be established from insects captured in the region of the type area and that their description should serve as the basis for future descriptions. It was pointed out that there is a lack of uniformity in the naming of closely related American sand flies and that some of the differences between populations of Lu. longipalpis are greater than those between accepted species. The majority of the participants agreed that the populations that have been defined in the literature as sibling species should be named.

Recent observations on the sand fly (Diptera: Psychodidae) fauna of the State of Rondônia, Western Amazônia, Brazil: the importance of Psychdopygus davisi as a vector of zoonotic cutaneous leishmaniasis

Sand flies were collected in the central region of the state of Rondônia (W 64 30' to 63 00' and S 10 00'to 11 00') using Shannon and CDC light traps from October 1997 to August 2000. A total of 85,850 specimens representing 78 named species were captured. Of these 14 were new records for Rondônia. The proportion of males/females was 1/1.131. Trypanosomatids, that are presently being identified, were detected in 11 species. Leishmania (Viannia) naiffi was recorded from Psychodopygus davisi and P. hirsutus. In the present study the dominant species was P. davisi (39.6 percent) followed by Lutzomyia whitmani (13.1 percent), P. carrerai (11.6 percent), and P. hirsutus (10.2 percent). The importance of P. davisi as a vector of zoonotic cutaneous leishmaniasis is discussed

Teste de aglutinaçäo directa no sorodiagnóstico da leishmaniose visceral no estado do Pará / Direct agglutination test in the serodiagnosis of human visceral leishmaniases in the State of Pará, Brazil

The direct agglutination test (DAT) was evaluated for serodiagnosis of visceral leishmaniasis (VL) in human and canids (dogs and foxes Cerdocyon thous). The results were compared with those of the immunofluorescent antibody assay (IFAT) and enzyme-linked immunosorbent assay (ELISA). The sera used were from: humans (303): confirmed VL (16), suspected VL (65), other conditions (102), negative controls (15) and individuals from an endemic area (105); dogs (82): from an endemic area (68), Salvaterra/Marajó/Pará (21 of which were parasitologically positive), and negative controls (14), from Belém; foxes (9): caught on Marajó Island. Antigens for DAT were prepared from promastigots of L. (L.) donovani, L. (L.) chagasi. Antigens used in ELISA and IFAT were prepared from promastigotes (soluble antigen) and amastigotes respectively of L. (L.) chagasi. In humans, the specificity and sensitivity of DAT using L. (L.) donovani were high (98.4 per cent and 100 per cent respectively) and comparable to that of IFAT (97.5 per cent and 100 per cent). ELISA was less specific (84.8 per cent) although similarly sensitive (100 per cent). In dogs, DAT was more specific using L. (L.) donovani as antigen than using L. (L.) chagasi. However, both DAT and ELISA were less sensitive (both 71.4 per cent) than IFAT (100 per cent). This difference was reflected in the results from endemic dogs, 87 per centof which were positive by IFAT but only 54 per cent by ELISA and 49 per cent by DAT. Similarly, all 9 fox sera were positive by IFAT, 7 of 9 (78 per cent) by ELISA but none by DAT. In conclusion, DAT using L. (L.) donovani antigen can provide a useful test for human VL; utilization on a large scale would be possible with a suitable reference laboratory to monitor antigen quality. However, DAT appears less useful for canine studies, as it was less sensitive than ELISA and especially IFAT in detecting canine infection.

Taxonomy of the genus Leishmania: present and future trends and their implications

The application of different taxonomic methods (Cladistic, Evolutionary Taxonomy and Numerical Taxonomy) to the taxonomy of the Genus Leishmania are reviewed. The major groupings of the most recent classifications obtained using the cladistical approach agree with the major divisions of previous classifications which used traditional taxonomy (Evolutionary Taxonomy). The advantage of the cladistical approach is that it produces cladograms whose branches indicate more accurately levels of relationships between the different taxa. Numerical Taxonomy is useful for identification but not as good as the cladistical approach for classification. The ancient division of this monophyletic genus into two major evolutionary lines supports the use of the subgeneric names Leishmania and Viannia.

Nota sobre leishmaniose canina no noroeste do Estado do Paraná, sul do Brasil / Leishmaniasis in dogs in southern Brazil

Em área endêmica de leishmaniose tegumentar americana no Município de Jussara, Estado do Paraná, Brasil, detectaram-se três cäes domésticos infectados por Leishmania (Viannia) brasiliensis

Leishmaniose cutânea experimental: III. Aspectos histopatológicos do comportamento evolutivo da lesäo cutânea produzida em Cebus apella (Primates: Cebidae) por Leishmania (Viannia) lainsoni, L. (V.) brasiliensis e L. (Leishmania) amazonensis / Experimental cutaneous leishmaniasis: III. Histophatological aspects of the evolutive behavior of the cutaneous lesion induced in Cebus apella (Primates: Cebidae) by Leishmania (Viannia) lainsoni, L. (V.) braziliensis and L. (Leishmania) amazonensis

Estudaram-se os aspectos histopatológicos relativos à evoluçäo da infecçäo experimental produzida em Cebus apella (Primates: Cebidae) por Leishmania (V.) lainsoni, L. (V.) braziliensis e L. (L.) amazonensis. O exame microscópico de biópsias seqüênciais, obtidas dos animais a intervalos definidos d etempo (a primeira, âs 48 ou 72 horas após a inoculaçäo, e as seguintes, a cada 30 dias), mostrou que o desenvolvimento das lesöes, independente da espécie de Leishmania inoculada, pass por uma seqüência de etapas a nível tecidual - 1) infiltrado inespecífico crônico; 2) nódulo macrofágico (com numerosos parasitas); 3) necrose das células parasitadas; 4) granuloma epitelióide; 5) absorçäo da área necrosada (às vezes formando granuloma de corpo estranho); 6) infiltrado inespecífico crônico residual); e 7) cicatrizaçäo - que representaria a formaçäo e a resoluçäo das lesöes. Discutiram-se também os prováveis mecanismso imunopatológicos que determinaram esta seqüência de eventos e sua possível semelhança com a evoluçäo das lesöes na leishmaniose tegumentar humana

Eimeria vitellini n. sp. (Apicomplexa: eimeriidae) from the brazilian toucan Rhamphastos vitellinus vitellinus Lichtenstein (Aves: Picicformes: Rhamplastidae)

Eimeria vitellini n. sp. is described from the faeces of the Rhamphastos v. vitellinus. Oocysts broadly ellipsoidal to oval (egg-shaped), 22,6 x 18.3 (20.0-25.0 x 16.3-22.5) micronm, shapeindex (length/width) 1.2 (1.1-1.1). Oocyst wall a single colourless layer about 0.5 micronm thick, becoming thinner at one ectremity, at which point the oocyst usually ruptures. No oocyst residuum, but 1 or 2 small polr bodies of about 1.0-1.5 x 0.5-1.0 micronm. Sporocysts ellongated ellipsoid (pearshaped), 14.3 x 7.5 (13.8-15.0 x 6.9-7.5) micronm, shape-index (1.9 (1.8-2.0), with a thin colourless wall bearing a very delicate Stieda body: a conspicuous sub-Stieda body is present. Sporozoites with anterior and posterior regractile bodies and strongly recurved around a bulky, compact sporocyst residuum composed of relatively fine granules and spherules

Leishmaniose cutânea experimental: II. Aspectos evolutivos da infecçäo no primata Cebus apella (Cebidae) pela Leishmania (V.) braziliensis e L. (L.) amazonensis / Experimental skin leishmaniasis: II. Course of the infection in the Cebus apella primate (Cebidae) caused by Leishmania (V.) braziliensis and L. (L.) amazonensis

Objetivando avaliar o potencial do primata C. apella como modelo experimental da leishmaniose cutânea produzida pela L. (V.) brasiliensis e L. (L.) amazonensis, inocularam-se, via intradérmica, 3 X10**6 de promastigotas dessas leishmanias, em 8 sítios da cauda de 10 espécimens desse desse primata, 5 deles com a L. (V.) braziliensis e outros 5 com a L. (L.) amazonensis. Posteriormente, às inoculaçöes, o exame semanal dos animais e biópsias mensais, revelaram os seguintes resultados relativos a cada parasita: a) L. (V.) brasiliensis: o periodo de incubaçäo foi d e15-20 dias; aos 30 dias evidenciaram-se lesöes pápulo-eritematosas, que evoluiram para nódulo ao fim de 60 dias; no 3§ mês, notou-se espontânea destas lesöes e, no 4§ mês, deu-se o inicio da reparaçäo das lesöes ulceradas, culminando com a cura em um dos animais após 5 meses, em dois após 6 meses, noutro após 7 meses e, no ultimo, após 10 meses. Quanto ao parasitismo nas lesöes, foi demonstrado nos 5 animais, até 90 dias; depois disto, somente em 2 até 120 dias e, por fim, até 180 dias apenas naquele que curou depois de 10 meses. b) L. (L.) amazonensis: o período de incubaçäo foi de 20 dias; aos 30 dias notou-se lesöes pápulo-eritematosas, que também evoluiram para nódulos ao fim de 60 dias, porém, a partir do 3§ mês, estas lesöes regrediram rapidamente ao fim de 90 dias, quando näo mais detectou-se o parasita na pele dos animais. Em relaçäo aos testes de Montenegro, somente 2 dos 5 animais infectados com a L. (V.) braziliensis reagiram ao teste, 6 e 90 dias após as inoculaçöes. Os resultados observados permitiram confirmar a infectividade do C. apella a estas leishmanias e, também, reforçar a indicaçäo desse primata como modelo experimental da leishmaniose cutânea por estes parasitas

Leishmaniose cutanea experimental: I-sobre a susceptibilidade do primata cebus apella (Cebidae) a infecçäo pela Leishmania (Viannia) Lainsoni Silveira, Shaw, Braga e Ishikawa, 1987 / Experimental cutaneous leishmaniasis: I-on the susceptibility of the primate cebus apella (Cebidae) to the infection caused by Leishmania (Viannia) Lainsoni Silveira, Shaw, Braga and Ishikawa, 1987

Foi investigada a susceptibilidade do primata Cebus apella (Cebidae) à infecçäo experimentada pela Leishmania (Viannia) lainsoni, com o objetivo de estudar a patogenia desse parasita, ainda pouco conhecido para o homem. Desse forma, cinco espécimes jovens daquele primata, 2 machos e 3 fêmeas, foram inoculados, itraderme, em oito sítios diferentes da regiäo dorsal da cauda com 3 x 10***6 de promastigotas do parasita (MHOM/BR/81/M6426, Benevides, Pará), obtidas de cultura da fase estacionária. Em seguida às inoculaçöes, a infecçäo experimental no animais foi comprovada, näo só pela presença de amastigotas do parasita na pele dos animais inoculados, mas, também, pela concomitância desse achado associado ao desenvolvimento de lesäo cutânea nos pontos da pele onde o parasita foi inoculado. Diante desses resultados, ficou demonstrada a susceptibilidade do primata Cebus apella à infecçäo experimental pela leishmania lainsoni, cujo período de infecçäo durou quese quatro meses, suficiente para testar drogas antileishmanióticas e estudar a patogênese da doença causada por este parasita

Sobre a sensibilidade da cultura de leucócitos circulantes na detecçäo de Leishmania no sangue periférico de pacientes com leishmaniose tegumentar / Sensitivity of the culture of circulating leucocytes in the detection of Leishmania in the peripheral blood of patients with tegumentary leishmaniasis

Foi investigada a presença de Leishmani, através da cultura de leucócitos circulantes, no sangue periférico de 60 pacientes portadores de leishmaniose tegumentar americana, nas suas diferentes formas clínicas, assim como nas principais fases evolutivas da doença. Biópsias de lesöes cutâneas e/ou de mucosa desses pacientes foram obtidas com a finalidade de isolar e caracterizar os parasitas, através da técnica de anticorpos monoclonais. Dos 60 pacientes examinados, foram isoladas 40 amostras de Leishmania das lesöes biopsiadas, sendo 5 de Leishmania (V.) brasiliensis, 3 de L. (V.) guyanensis, 1 de L. (V.) lainsoni, 13 de L. (L.) amazonensis e 18 näo puderam ser caracterizados a nível específico, porém, reagiram com anticorpos monoclonais do grupo brazilensis. Quanto à pesquisa através das culturas de leucócitos circulantes, esta revelou resultados completamente negativos. Com base nesses achados, os autores concluíram ser pouco consciente atribuir valor à cultura de leucócitos para o diagnóstico da leishmaniose tegumentar

Infective stages of Leishmania in the sandfly vector and some observations on the mechanism of transmission

Foi demonstrado através de infecçäo experimental, que estágios infectivos de Leishmania (L.) amazonensis, capazes de produzir infecçäo na pele do hamster, encontram-se presentes no vetor flebotomíneo Lutzomyia flaviscutellata 15, 25, 40, 49, 70, 96 e 120 horas após o inseto ter recebido sua refeiçäo sangüínea infectiva. Da mesma maneira, foi comprovada a presença de estágios infectivos de L. (L.) chagasi em exemplares do vetor Lu. longipalpis, examinados 38, 50, 63, 87, 110, 135, 171 e 221 horas após o repasto sangüíneo infectivo - através da inoculaçäo em hamster por via intraperitoneal dos flagelados obtidos desses fle botomíneos. A questäo sobre a transmissäo do gênero Leishmania pelo flebotomíneo ser ou näo dependente da presença de promastigotos "metacíclios" na proboscisa do vetor, é discutida