Ecological characteristics of Triatoma patagonica at the Southern limit of its distribution (Chubut, Argentina)

This study aimed at identifying the ecological characteristics of Triatoma patagonica Del Ponte 1929 (Hemiptera: Reduviidae) and evaluating the epidemiological importance of this species at its southernmost distribution limit. We carried out two surveys in the Province of Chubut, in summer and in spring, 1998. In each survey, we interviewed local health care agents for triatomine recognition and reports of the bugs, followed by entomological searches in houses and peridomestic and silvatic biotopes. The presence of T. patagonica was confirmed in two of the five localities indicated by interview. In agreement with previous studies, all these positive localities were east of the 11°C isotherm, within the Monte phytogeographic province. Triatomine abundance and infestation levels (in peridomiciles and peridomestic biotopes) were higher in summer than in spring, possibly reflecting adverse environmental conditions such as flood and cold winter weather. In the silvatic environment, we found three adult bugs under rocks in summer. In peridomestic sites bugs were only found associated with chickens, which were also the only blood meal source identified. Infection by Trypanosoma cruzi was not detected. We conclude that T. patagonica at its southernmost distribution limit does not represent a risk to public health due to its low abundance, lack of association with humans, and absence of T. cruzi infection.

Techniques of DNA-studies on prehispanic ectoparasites (Pulex sp., Pulicidae, Siphonaptera) from animal mummies of the Chiribaya Culture, Southern Peru

During a paleoparasitological survey of several animal mummies (Cavia aperea f. porcellus and Canis familiaris) from Chiribaya Baja, an archaeological site in Southern Peru, an unexpected find was made. In the well preserved fur, large numbers of mummified fleas (Pulex simulans/irritans)that parasitized the animals during life were encountered. Due to the relative recent event of the host mummification and the outstanding preservation of the fleas, an attempt for the retrieval of DNA was made. A DNA extraction and sequencing protocol for archaeological ectoparasitic remains has been established, taking additional studies for tissue and protein preservation into account. Tissue preservation was assessed with transmission electron microscopy and the protein preservation was tested through the racemisation ratios of aspartic acid. Regions of the 28S rDNA gene were successfully amplified and sequenced. Further research perspectives are outlined.

Louse infestation of the Chiribaya Culture, Southern Peru: variation in prevalence by age and sex

In order to improve the interpretive potential of archaeoparasitology, it is important to demonstrate that the epidemiology of ancient parasites is comparable to that of modern parasites. Once this is demonstrated, then we can be secure that the evidence of ancient parasitism truly reflects the pathoecology of parasitic disease. Presented here is an analysis of the paleoepidemiology of Pediculus humanus infestation from 146 mummies from the Chiribaya culture 1000-1250 AD of Southern Peru. The study demonstrates the modern parasitological axiom that 10% of the population harbors 70% of the parasites holds true for ancient louse infestation. This is the first demonstration of the paleoepidemiology of prehistoric lice infestation.

Taxonomic reports of Otobothrioidea (Eucestoda, Trypanorhyncha) from elasmobranch fishes of the southern coast off Brazil

Specimens of elasmobranch fishes, captured in the states of Paraná and Santa Catarina, of the southern coast off Brazil, represented by three families, four genera, and four species, were parasitized with otobothrioid trypanorhynch cestodes: Heptranchias perlo (Bonnaterre, 1788), Squalus sp. and Carcharhinus signatus (Poey, 1868) were parasitized with Progrillotia dollfusi Carvajal & Rego,1987; Prionace glauca (Linnaeus, 1758) with Molicola horridus (Goodsir, 1841) Dollfus, 1942. Details of internal morphology and/or scolex and/or proglottids surface ultrastructure, that expanded the description of M. horridus, through observations with lightfield, and/or scanning eletronic microscopy, are provided. The known geographical distribution for the species M. horridus is enlarged. P. dollfusi is reported for the first time in elasmobranchs.

Blackflies (Diptera: Simuliidae) of Southern Guyana with keys for the identification of adults and pupae: a review

A revision is made of the previously poorly studied blackfly fauna from the south-western border of Guyana with Brazil. Notes on the biosystematics of the species found are provided, together with keys and illustrations based on their morphology. Of the 14 species recorded, eight are anthropophilic and two of these (Simulium oyapockense s.l. and S. guianense s.l.) are proven vectors of human onchocerciasis in the nearby Amazonia focus of the disease in neighbouring Brazil.

Association of human leukocyte antigen DQ1 and dengue fever in a white Southern Brazilian population

Dengue is an infectious disease of viral etiology transmitted by the mosquitoes Aedes aegypti, A. albopictus, and A. scutellaris. It can develop either as a benign form or as a severe hemorrhagic form. Previous work showed an association of the hemorrhagic form with human leukocyte antigens (HLA), suggesting a role of genetic factors in disease susceptibility. Nevertheless, data on HLA association with the classical form of the disease is scarce in literature. Sixty-four patients and 667 normal individuals, living in the state of Paraná, Southern Brazil, were used as test and control group, respectively. The patients developed the disease during a virus 1 dengue outbreak either in Maringá city in 1995 (47) or in Paranavaí city in 1999 (17). The diagnostic was confirmed through serology and/or viral culture. HLA class I and II typing was performed by the classical microlynfocitotoxicity test using monoclonal antisera and fluorobeads. Qui-square statistical analysis confirmed a positive association with HLA-DQ1 (76.6% vs 57.7%; p = 0.005243; pc = 0.026215). HLA-DR1 also presented an increased frequency in the test group, not statistically significant after p correction though (32.8% vs 15.9%; p = 0.005729; pc = 0.080206). In conclusion, genetic factors may play a role on the susceptibility to the classical dengue, virus 1, in the Brazilian population. Further independent studies should be performed in the Brazilian population to confirm these preliminary data.

Molecular differentiation of Anopheles (Nyssorhynchus) benarrochi and An. (N.) oswaldoi from Southern Colombia

Anopheles (Nyssorhynchus) benarrochi, An. (N.) oswaldoi, and An. (N.) rangeli are the most common anthropophilic mosquitoes in the southern Colombian state of Putumayo. Adult females are most commonly collected in epidemiological studies, and this stage poses significant problems for correct identification, due to overlapping inter-specific morphological characters. Although An. rangeli is easy to identify, the morphological variant of An. benarrochi found in the region and An. oswaldoi are not always easy to separate. Herein we provide a rapid molecular method to distinguish these two species in Southern Colombia. Sequence data for the second internal transcribed spacer (ITS2) region of rDNA was generated for link-reared progeny of An. benarrochi and An. oswaldoi, that had been identified using all life stages. ITS2 sequences were 540 bp in length in An. benarrochi (n = 9) and 531 bp in An. oswaldoi (n = 7). Sequences showed no intra-specific variation and ungapped inter-specific sequence divergence was 6.4%. Species diagnostic banding patterns were recovered following digestion of the ITS2 amplicons with the enzyme Hae III as follows: An. benarrochi (365, 137, and 38 bp) and An. oswaldoi (493 and 38 bp). This polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay provides rapid, accurate, and inexpensive species diagnosis of adult females. This will benefit future epidemiological studies and, as PCR amplification can be achieved using a single mosquito leg, the remaining specimen can be either retained as a morphological voucher or further used in vector incrimination studies. That An. benarrochi comprises a complex of at least two species across Latin America is discussed.

Incrimination of Anopheles (Nyssorhynchus) rangeli and An. (Nys.) oswaldoi as natural vectors of Plasmodium vivax in Southern Colombia

Malaria transmission in the Southern Colombian state of Putumayo continues despite the absence of traditional vector species, except for the presence of Anopheles darlingi near the southeastern border with the state of Amazonas. In order to facilitate malaria vector incrimination in Putumayo, 2445 morphologically identified Anopheles females were tested for natural infection of Plasmodium vivax by ELISA. Specimens tested included An. apicimacula (n = 2), An. benarrochi B (n = 1617), An. darlingi (n = 29), An. mattogrossensis (n = 7), An. neomaculipalpus (n = 7), An. oswaldoi (n = 362), An. peryassui (n = 1), An. punctimacula (n = 1), An. rangeli (n = 413), and An. triannulatus (n = 6). Despite being overwhelmingly the most anthropophilic species in the region and comprising 66.1% of the mosquitoes tested, An. benarrochi B was not shown to be a vector. Thirty-five An. rangeli and one An. oswaldoi were naturally infected with P. vivax VK210. Sequence data were generated for the nuclear second internal transcriber space region of 31 of these 36 vivax positive mosquitoes (86.1%) to confirm their morphological identification. An. oswaldoi is known to be a species complex in Latin America, but its internal taxonomy remains unresolved. Herein we show that the An. oswaldoi found in the state of Putumayo is genetically similar to specimens from the state of Amapá in Brazil and from the Ocama region in the state of Amazonas in Venezuela, and that this form harbors natural infections of P. vivax. That An. rangeli and this member of the An. oswaldoi complex are incriminated as malaria vectors in Putumayo, is a novel finding of significance for malaria control in Southern Colombia, and possibly in other areas of Latin America.

Taeniasis-cysticercosis in Southern Ecuador: assessment of infection status using multiple laboratory diagnostic tools

Taenia solium-taeniasis and cysticercosis were studied in the human and porcine populations of a rural community in the Southern Ecuadorian Andes. From the 1059 inhabitants, 800 serum samples and 958 stool samples could be collected. In addition, 646 from the estimated 1148 pigs were tongue inspected. Circulating antigen was detected by enzyme linked immunosorbent assay (Ag-ELISA) in 2.25% of the human population, whereas intestinal taeniasis was detected in 1.46% by the formalin-ether technique. Following treatment and recovery of tapeworm fragments these were all identified as T. solium. Porcine cysticercosis was diagnosed in 3.56% of the pigs by tongue inspection. In addition, enzyme linked immunoelectrotransfer blot (EITB) was performed on a subset group of 100 humans to confirm the results of the Ag-ELISA. One hundred serum samples from pigs were also analysed by EITB. It appeared that 43 and 74% of humans and pigs had antibodies against T. solium cysticerci, respectively. It is concluded that contrary to the high exposure of the human population to T. solium that is suggested by EITB, the number of active cysticercosis cases, diagnosed by Ag-ELISA, was low, which may indicate endemic stability. The further use of complementary diagnostic methods for a better understanding of the epidemiology of T. solium is suggested.

Health at the time of Native-European contact in Southern Patagonia: First steps, results, and prospects

The objective of this paper is to present the first steps into the study of health in southern Patagonia during pre and post Native-European contact. Thus, our work has a double purpose. First, to discuss characteristics and relevance of human bone records of southern Patagonia, in order to study health in a population context. Second, to show some new lines of information, which include paleoparasitology, nutritional paleopathologies, and the study of lifestyles from human remains. In this context, we have started working on the first Spanish settlement "Nombre de Jesus", founded in 1584, and with historical documentation of "La Candelaria" Mission in Rio Grande (1896-1931).

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.

High proportion of hepatitis C virus genotypes 1 and 3 in a large cohort of patients from Southern Brazil

Hepatitis C virus (HCV) isolates have been divided into six genotypes (1 to 6). The duration of hepatitis C standard treatment is 48 weeks for patients infected with HCV genotype 1 vs 24 weeks for those infected with genotypes 2 and 3. A total of 1544 HCV isolates from chronic patients living in the southern Brazilian states of Rio Grande do Sul (RS, n = 627) and Santa Catarina (SC, n = 917) were genotyped by restriction fragment length polymorphism (RFLP) of polymerase chain reaction (PCR) products. In RS, 338 (53.9%; 95% CI 50.0 - 57.8%), 34 (5.4%; 95% CI 3.8 - 7.4%) and, 255 (40.7%; 95% CI 36.9 - 44.6%) samples were from genotypes 1, 2, and 3, respectively. In SC, 468 (51%; 95% CI 47.8 - 54.2%), 26 (2.9%; 95% CI 1.9 - 4.1%) and, 423 (46.1%; 95% CI 42.9 - 49.3%) samples were from genotypes 1, 2, and 3, respectively. Genotyping results were confirmed by direct nucleotide sequencing of PCR products derived from 68 samples, without any discrepancy between PCR-RFLP and nucleotide sequencing methods. In conclusion, almost half of the hepatitis C patients from South of Brazil are infected by genotypes 2 and 3 and, these results have important consequential therapeutic implications as they can be treated for only 24 weeks, not 48.

Southern Cone Initiative for the elimination of domestic populations of Triatoma infestans and the interruption of transfusion Chagas disease: historical aspects, present situation, and perspectives

Created in 1991 by the governments of Argentina, Bolivia, Brazil, Chile, Paraguay, and Uruguay, the Southern Cone Initiative (SCI) has been extremely important for Chagas disease control in this region. Its basic objective was to reach the interruption of this disease, chiefly by means of the elimination of the principal vector Triatoma infestans and by the selection of safe donors in the regional blood banks. After a summarized historic of SCI, the text shows the advance of technical and operative activities, emphasizing some factors for the initiative success, as well as some difficulties and constraints. The future of SCI will depend of the continuity of the actions and of political priority. Scientific community has been highly responsible for this initiative and its maintenance. At the side of this, national and international efforts must be involved and reinforced to assure the accomplishment of the final targets of SCI. Very specially, the Pan American Health Organization has cooperated with the Initiative in all its moments and activities,being the most important catalytic and technical factor for SCI success.