Human immunodeficiency virus/acquired immunodeficiency syndrome and tropical diseases: a Brazilian perspective

The paper summarizes recent findings on the epidemiology and pathogenesis of human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/Aids), highlighting the role of co-infections with major tropical diseases. Such co-infections have been studied in the Brazilian context since the beginning of the Aids epidemic and are expected to be more frequent and relevant as the Aids epidemic in Brazil proceeds towards smaller municipalities and the countryside, where tropical diseases are endemic. Unlike opportunistic diseases that affect basically the immunocompromised host, most tropical diseases, as well as tuberculosis, are pathogenic on their own, and can affect subjects with mild or no immunossuppression. In the era of highly active anti-retroviral therapies (HAART), opportunistic diseases seem to be on decrease in Brazil, where such medicines are fully available. Benefiting from HAART in terms of restoration of the immune function, putative milder clinical courses are expected in the future for most co-infections, including tropical diseases. On the other hand, from an ecological perspective, the progressive geographic diffusion of Aids makes tropical diseases and tuberculosis a renewed challenge for Brazilian researchers and practitioners dealing with HIV/Aids in the coming years.

Studies on the biology of schistosomiasis with emphasis on the Senegal river basin

The construction of the Diama dam on the Senegal river, the Manantali dam on the Bafing river, Mali and the ensuing ecological changes have led to a massive outbreak of Schistosoma mansoni in Northern Senegal, associated with high intensity of infections, due to intense transmission, and the creation of new foci of S. haematobium. Data on the vectorial capacity of Biomphalaria pfeifferi from Ndombo, near Richard Toll, Senegal are presented with sympatric and allopatric (Cameroon) S. mansoni. Comparisons are made on infectivity, cercarial production, chronobiology of cercarial emergence and longevity of infected snails. Recent data on the intermediate host specificity of different isolates of S. haematobium from the Lower and Middle Valley of the Senegal river basin (SRB) demonstrate the existence of at least two strains of S. haematobium. The role of Bulinus truncatus in the transmission of S. haematobium in the Lower and Middle Valleys of the SRB is reviewed. Both S. haematobium and S. mansoni are transmitted in the same foci in some areas of the SRB.

Ecological Data of Travassosnema travassosi travassosi (Dracunculoidea: Guyanemidae) from the Humour of the Eyes of Acestrorhynchus lacustris from Tibagi River, Paraná, Brazil

Data obtained between 1990 and 1995 provide, for the first time, ecological information of the parasitic nematode Travassosnema travassosi travassosi Costa, Moreira & Oliveira, 1991 from Acestrorhynchus lacustris (Characiformes: Acestrorhynchidae) collected in the Tibagi River, Sertanópolis, Paraná, Brazil. These nematode occurred with low prevalences (7.7% to 28.6%) and intensities (1 to 3) during almost the whole year. The observation of mature females throughout the year indicate that liberation of larvae can occur during all the year around. This is the first report on the occurrence of T. travassosi travassosi inside the eyes. These nematodes were mostly located in humour of the eyes (87% of cases), being less frequently detected in tissues behind the eyes (13% of cases).

A New Species of Kritskyia (Dactylogyridae, Ancyrocephalinae) Parasite of Urinary Bladder of Prochilodus lineatus (Prochilodontidae, Characiformes) from the Floodplain of the High Paraná River, Brazil

A new species of Kritskyia inhabits the urinary bladder of the "curimba", Prochilodus lineatus in the floodplain of the high Paraná river. The new species resembles others members of Kritskyia in the following features: haptor lacking anchors and with 14 hooks marginal, posterior male copulatory organ non articulated with the accessory piece and vagina a sclerotized tube. However, it differs from the known species mainly by the shape of the copulatory complex. This is the third endoparasitic monogenean species reported from freshwater Neotropical fish.

Identification of Human T-lymphotropic Virus Type I (HTLV-I) Subtypes Using Restrited Fragment Length Polymorphism in a Cohort of Asymptomatic Carriers and Patients with HTLV-I-associated Myelopathy/tropical Spastic Paraparesis from São Paulo, Brazil

Although human T-lymphotropic virus type I (HTLV-I) exhibits high genetic stability, as compared to other RNA viruses and particularly to human immunodeficiency virus (HIV), genotypic subtypes of this human retrovirus have been characterized in isolates from diverse geographical areas. These are currently believed not to be associated with different pathogenetic outcomes of infection. The present study aimed at characterizing genotypic subtypes of viral isolates from 70 HTLV-I-infected individuals from São Paulo, Brazil, including 42 asymptomatic carriers and 28 patients with HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), using restricted fragment length polymorphism (RFLP) analysis of long terminal repeat (LTR) HTLV-I proviral DNA sequences. Peripheral blood mononuclear cell lysates were amplified by nested polymerase chain reaction (PCR) and amplicons submitted to enzymatic digestion using a panel of endonucleases. Among HTLV-I asymptomatic carriers, viral cosmopolitan subtypes A, B, C and E were identified in 73.8%, 7.1%, 7.1% and 12% of tested samples, respectively, whereas among HAM/TSP patients, cosmopolitan A (89.3%), cosmopolitan C (7.1%) and cosmopolitan E (3.6%) subtypes were detected. HTLV-I subtypes were not statistically significant associated with patients' clinical status. We also conclude that RFLP analysis is a suitable tool for descriptive studies on the molecular epidemiology of HTLV-I infections in our environment.

Proteocephalidean larvae (Cestoda) in naturally infected cyclopid copepods of the upper Paraná River floodplain, Brazil

The occurrence, prevalence and infection intensity of proteocephalidean larvae in naturally infected intermediate hosts of the Upper Paraná River floodplain are reported. A total of 5,206 zooplanktonic and benthic organisms were analyzed, namely cyclopid (2,621) and calanoid (1,479) copepods, cladocerans (704), rotifers (307), chironomid larvae (41) and ostracods (54). Eight cyclopid copepods - two copepodids, one male and five females - comprising 0.3% of the cyclopid copepods examined, were naturally infected. The male infected belonged to a species of Paracyclops, and the females to Paracyclops sp., Thermocyclops minutus and Mesocyclops longisetus.

Horizontal stratification of the sand fly fauna (Diptera: Psychodidae) in a transitional vegetation between caatinga and tropical rain forest, state of Bahia, Brazil

A study about the horizontal stratification of the sand fly fauna in two distinct ecosystems, caatinga area, endemic for visceral leishmaniasis, and the tropical rain forest area, endemic for cutaneous leishmaniasis, was performed in the state of Bahia, Brazil. Lutzomyia longipalpis was predominant in the caatinga, and following it came the species L. capixaba and L. oswaldoi. In the tropical rain forest other species were found, such as L. intermedia, L. migonei, L. whitmani, L. yuilli, L.fischeri, L. damascenoi, L. evandroi, L. monticola, and L. lenti. It was found that the geographical limits of the vector species of visceral and cutaneous leishmaniasis are clearly defined by the biological and phytogeographic characteristics.

Standardization of in-house polymerase chain reaction for the identification of Mycobacterium tuberculosis at the reference tropical disease hospital in the State of Goiás, Brazil

This study compares smear, growth in Lowenstein-Jensen medium, and in-house polymerase chain reaction (PCR) techniques for the detection of Mycobacterium tuberculosis. A total of 72 specimens from 72 patients with clinical symptoms of tuberculosis, including 70 sputum and two bronchial aspirate samples, were tested in parallel by smear, culture, and in-house PCR techniques. From these, 48 (66.6%) were negative by the 3 methods, 2 (2.8%) were smear positive and negative by culture and in-house PCR, 11 (15.3%) were both smear and culture negative, and in-house PCR positive, 7 (9.7%) were positive by the 3 methods, 2 (2.8%) were positive by smear and culture, and negative by PCR, 2 (2.8%) were positive by culture and PCR, but smear negative. After the resolution of discrepancies in PCR results, the sensitivity and specificity for in-house PCR technique to M. tuberculosis relative to the culture, were 81.8% and 81.9%, respectively. These results confirm that this method, in-house PCR, may be a sensitive and specific technique for M. tuberculosis detection, occurring in both positive and negative smear and negative cultures.

Isolation and characterization of the full-length cDNA encoding a member of a novel cytochrome p450 family (CYP320A1) from the tropical freshwater snail, Biomphalaria glabrata, intermediate host for Schistosoma mansoni

Cytochrome p450s (cyp450s) are a family of structurally related proteins, with diverse functions, including steroid synthesis and breakdown of toxins. This paper reports the full-length sequence of a novel cyp450 gene, the first to be isolated from the tropical freshwater snail Biomphalaria glabrata, an important intermediate host of Schistosoma mansoni. The nucleotide sequence is 2291 bp with a predicted amino acid sequence of 584aa. The sequence demonstrates conserved cyp450 structural motifs, but is sufficiently different from previously reported cyp450 sequences to be given a new classification, CYP320A1. Initially identified as down-regulated in partially resistant snails in response to S. mansoni infection, amplification of this gene using RT-PCR in both totally resistant or susceptible snail lines when exposed to infection, and all tissues examined, suggests ubiquitous expression. Characterization of the first cyp450 from B. glabrata is significant in understanding the evolution of these metabolically important proteins.

The feature of papers and citation analysis of eleven journals in tropical medicine indexed by Science Citation Index Expanded

To determine the features of papers, authors, and citation of eleven journals in tropical medicine indexed by Science Citation Index Expanded, the database of the Institute for Scientific Information, we analyzed original articles, editorials, reviews, corrections, letters, biographies, and news published in these journals. The results show that these journals covered 107 countries or regions on six continents. The average number of reference was 23.05, with 87.89% of the references from periodicals. The Price Index was 31.43% and the self-citing rate was 7.02%. The references in the first 20 journals ranked by the amount of citation accounted for 36.71% of the total citations. Brazil, United States, India, and England are more advanced in tropical medicine research. The conclusion is that these journals covered most research done in these countries or regions. Most researches were done by cooperation of the researchers, but many of the publications used outdated articles and should include newer information.

Morphobiological aspects of Rhodnius brethesi Matta, 1919 (Hemiptera:Reduviidae) from the Upper and Middle Negro River, Amazon region of Brazil: I - scanning electron microscopy

The occurrence of autochthonous cases of Chagas disease in the Amazon region of Brazil over recent decades has motivated an intensification of studies in this area. Different species of triatomines have been identified, and ten of these have be proven to be carriers of the parasite Trypanosoma cruzi or " cruzi-like " parasites. Studies conducted in the municipalities of Santa Isabel do Rio Negro and Barcelos, located on the Upper and Middle of the Negro River, microregion of Negro River, state of Amazonas have confirmed not only that Rhodnius brethesi is present in the palm tree Leopoldinia piassaba, but also that this insect was recognized by palm fiber collectors. A morphological study of eyes, inter-ocular and inter-ocellar regions, antennae, buccula, labrum, rostrum, stridulatory sulcus and feet, including the apex of the tibia, spongy fossette and ctenidium was conducted by scanning electron microscopy. The buccula and the stridulatory sulcus presented notable differences in specimens of different genera and also of different species. These data make it possible to suggest that the details presented in these structures can be included as diagnostic characteristics to be used in new dichotomous keys, thereby contributing towards studies of taxonomy and systematics and furnishing backing for comparative analysis of specimens collected from different localities.

Lack of tax diversity for tropical spastic paraparesis/human T-cell lymphotropic virus type 1 (HTLV-I) associated myelopathy development in HTLV-I-infected subjects in São Paulo, Brazil

The product of human T-cell lymphotropic virus type 1 (HTLV-1) tax gene has a transactivating effect of the viral and cellular gene expression. Genetic variations in this gene have been correlated with differences in clinical outcomes. Based upon its diversity, two closely related substrains, namely tax A and tax B, have been described. The tax A substrain has been found at a higher frequency among human T-cell leukemia virus type 1 (TSP/HAM) patients than among healthy HTLV-I-infected asymptomatic subjects in Japan. In this study, we determined the distribution of tax substrains in HTLV-I-infected subjects in the city of São Paulo, Brazil. Using the ACCII restriction enzyme site, we detected only tax A substrain from 48 TSP/HAM patients and 28 healthy HTLV-I carriers. The sequenced tax genes from nine TSP/HAM patients and five asymptomatic HTLV-I carriers showed a similar pattern of mutation, which characterizes tax A. Our results indicate that HTLV-I tax subtypes have no significant influences on TSP/HAM disease progression. Furthermore, monophyletic introduction of HTLV-I to Brazil probably occurred during the African slave trade many years ago.

Biomphalaria tenagophila potencial vector of Schistosoma mansoni in the Paraná River basin (Argentina and Paraguay)

Susceptibility and compatibility experiments were carried out with 700 Biomphalaria tenagophila from the Paraná River basin exposed to infection with Schistosoma mansoni. Individual infection was performed with 10 miracidia of SJ2 strain from the Paraiba valley (Brazil) originally infective to B. tenagophila. These snails were laboratory-breed progeny of B. tenagophila collected from six localities of Argentina and one from Paraguay. From Argentina: Rincón de Vences (7%) and Posadas (11%) became infected with S. mansoni and the calculation of Frandsen's index (TCP/100) shows that they were Class II poorly compatible. Those snails from Goya (22%), Maloyas (5%), and Berón de Astrada (3%) were Class III compatible to the S. mansoni. None of the 100 snails exposed from Caá-Catí became infected (Class 0 incompatible). Tested samples from Paraguay (Encarnación) were infected (20%) and compatible (Class III). It was also studied the persistence of the infection in 244 snails of the first generation (F1) of those that were susceptible from three places. It was demonstrated an increment of the susceptibility in the F1 from Maloyas (chi2 = 27.22; p = 0.0001) and Posadas (chi2 = 4.24; p = 0.04). The results point out the possibility that schistosomiasis might be able to spread into the Paraná River basin where B. tenagophila exists.

Vector bionomics and malaria transmission in the Upper Orinoco River, Southern Venezuela

A longitudinal epidemiological and entomological study was carried out in Ocamo, Upper Orinoco River, between January 1994 and February 1995 to understand the dynamics of malaria transmission in this area. Malaria transmission occurs throughout the year with a peak in June at the beginning of the rainy season. The Annual Parasite Index was 1,279 per 1,000 populations at risk. Plasmodium falciparum infections accounted for 64% of all infections, P. vivax for 28%, and P. malariae for 4%. Mixed P. falciparum/P. vivax infections were diagnosed in 15 people representing 4% of total cases. Children under 10 years accounted for 58% of the cases; the risk for malaria in this age group was 77% higher than for those in the greater than 50 years age group. Anopheles darlingi was the predominant anopheline species landing on humans indoors with a biting peak between midnight and dawn. A significant positive correlation was found between malaria monthly incidence and mean number of An. darlingi caught. There was not a significant relationship between mean number of An. darlingi and rainfall or between incidence and rainfall. A total of 7295 anophelines were assayed by ELISA for detection of Plasmodium circumsporozoite (CS) protein. Only An. darlingi (55) was positive for CS proteins of P. falciparum (0.42%), P. malariae (0.25%), and P. vivax-247 (0.1%). The overall estimated entomological inoculation rate was 129 positive bites/person/year. The present study was the first longitudinal entomological and epidemiological study conducted in this area and set up the basic ground for subsequent intervention with insecticide-treated nets.

Molecular and morphological characterization of heterorhabditid entomopathogenic nematodes from the tropical rainforest in Brazil

Despite massive losses of primary forest, the Amazonian rainforest remains an extremely rich source of biodiversity. In recent years, entomopathogenic nematodes (EPNs) have been isolated from soil in various parts of the world and used successfully as biological control agents against numerous insect pests. Therefore, a sampling in the rainforest of Monte Negro, Rondônia, Brazil was conducted with the aim of discovering new strains and/or species of EPNs for future development as biological control agents. From 156 soil samples taken at nine collecting sites, 19 isolates were obtained, all of them belonging to the genus Heterorhabditis. Four strains were subjected to detailed morphological and molecular evaluation. Based on morphometrics and internal transcribed spacer (ITS) sequence data, the strains LPP1, LPP2 and LPP4 were identified as Heterorhabditis indica, whereas LPP7 was considered Heterorhabditis baujardi. Comparative analysis of the ITS1 sequence of H. indica and H. baujardi isolates showed a polymorphic site for the restriction enzyme Tth 111 that could be used to distinguish the two species. Consequently, strains LPP1, LPP2, LPP3, LPP4, and LPP9 were identified as H. indica, whereas LPP5, LPP7, LPP8 and LPP10 were identified as H. baujardi.