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At least 307 records · Page 17Linked to original sources
PubMed2001

Chemical ecology of triatomine bugs: vectors of Chagas disease.

Knowledge of chemical ecology of haematophagous triatomine bugs (Hemiptera: Heteroptera: Reduviidae) could be of practical value because this polyphyletic subfamily includes species of medical importance, such as vectors of Trypanosoma cruzi Chagas (Kinetoplastida: Trypanosomatidae), the aetiological agent of Chagas disease. For particular species of Dipetalogaster, Panstrongylus, Rhodnius and Triatoma, therefore, we review information on exocrine glands and products, interpreting their apparent roles as semiochemicals in the aggregation, alarm, defence, host-finding and sexual behaviour of these Triatominae.

Animals↗
PubMed1991

[Entomological surveillance of Chagas' disease in the State of Sao Paulo].

Drastic modifications in agrarian space, with the reductions of primary forests, along with changes in rural production systems have led to the growth of salaried employment and also caused rural workers to move to the peripheral areas of cities. There has also been an intense and continuous intervention undertaken by the Superintendência de Controle de Endemias (SUCEN) through the use of pesticides in the fight against triatomine bugs in houses and peridomestic areas of the State of S. Paulo. All these factors have contributed to the interruptions of the natural transmission of Chagas' disease in S. Paulo. The next step in the program was the integration of vertical vector control into primary health care involving community participation. The several years of SUCEN's work among the rural communities has encouraged them to notify the presence of triatominae bugs, and prompt response to each notification has led to the growth of the process of permanent participation. Data from 1985 and 1986 showed that 85.6% of the bugs captured inside houses were notified by the population, which confirms that the best way to maintain the epidemiologic surveillance of Chagas' disease by the mobilization of local communities for effective participation in vector surveillance.

Animals↗
PubMedDate not supplied

Control of Chagas disease vectors.

Most Latin American countries are making dramatic progress in controlling Chagas disease, through a series of national and international initiatives focusing on elimination of domestic populations of Triatominae, improved screening of blood donors, and clinical support and treatment of persons infected with Trypanosoma cruzi. Some countries, particularly Uruguay, Chile and Brazil, are sufficiently advanced in their programmes to initiate detailed planning of the subsequent phases of Chagas disease control, while others such as Peru, Ecuador, and Mexico, are currently applying only the initial phases of the control campaigns. In this review, we seek to provide a brief history of the campaigns as a basis for discussion of future interventions. Our aim is to relate operational needs to the underlying biological aspects that have made Chagas disease so serious in Latin America but have also revealed the epidemiological vulnerability of this disease. The English version of this paper is available too at: http://www.insp.mx/salud/index.html.

Animals↗
PubMedDate not supplied

Chagas' disease in the Brazilian Amazon. I--A short review.

At least eighteen species of triatominae have been found in the Brazilian Amazon, nine of them naturally infected with Trypanosoma cruzi or "cruzi-like" trypanosomes and associated with numerous wild reservoirs. Despite the small number of human cases of Chagas' disease described to date in the Brazilian Amazon the risk that the disease will become endemic in this area is increasing for the following reasons: a) uncontrolled deforestation and colonization altering the ecological balance between reservoir hosts and wild vectors; b) the adaptation of reservoir hosts of T. cruzi and wild vectors to peripheral and intradomiciliary areas, as the sole feeding alternative; c) migration of infected human population from endemic areas, accompanied by domestic reservoir hosts (dogs and cats) or accidentally carrying in their baggage vectors already adapted to the domestic habitat. In short, risks that Chagas' disease will become endemic to the Amazon appear to be linked to the transposition of the wild cycle to the domestic cycle in that area or to transfer of the domestic cycle from endemic areas to the Amazon.

Adaptation, Physiological↗
PubMed2003

[Chagas' disease in the Amazon: an overview of the current situation and perspectives for prevention].

American Trypanosomiasis (Chagas' disease) due to Trypanosoma cruzi in the Amazon Region has become a target of scientific preoccupation in recent years because of the wide dispersion of infected vectors and intensive human migration into the region. An European Community and Latin America Triatominae Network international workshop held in July 2002 analyzed the general situation and the perspectives of human Chagas' disease in the area, concluding that although its occurrence remains sporadic, there is strong potential for the disease to spread, and a requirement for an integrated surveillance effort to be shared by all countries of the region.

Animals↗
PubMed1999

Elimination of vector-borne transmission of Chagas disease.

The control of the vector-borne transmission of Chagas disease in Brazil was organized as a national program in 1975, when two large entomological and sero-epidemiological surveys were conducted in the country in order to identify areas at highest risk of transmission and to guide interventions regarding the chemical treatment of domestic vectors of the disease. The authors present the baseline data gathered through these studies and compare them with more recent data. The evaluation performed shows that the transmission by Triatoma infestans is virtually interrupted and that the transmission by other native species of triatominae from different regions of the country is possibly very low. It is emphasized the need to maintain permanent actions of entomological surveillance in order to prevent recurrent transmission.

Adolescent↗
PubMedDate not supplied

Trypanosoma cruzi - the vector-parasite paradox.

Trypanosoma cruzi and the majority of its insect vectors (Hemiptera, Reduviidae, Triatominae) are confined to the Americas. But while recent molecular studies indicate a relatively ancient origin for the parasite ( approximately 65 million years ago) there is increasing evidence that the blood-sucking triatomine vectors have evolved comparatively recently (<5 mya). This review examines the evidence for these ideas, and attempts to reconcile the apparent paradox by suggesting that marsupial opossums (Didelphidae) may have played a role, not just as original reservoir hosts, but also as original vectors of the parasite.

Animals↗
PubMed2002

Abundance of Mepraia spinolai in a Periurban zone of Chile.

Mepraia spinolai is a silvatic species of Triatominae which prefers microhabitats near to or in rock piles. It is also able to maintain similar or higher size populations near houses. The density of bugs in quarries near Santiago, Chile, differed within microhabitats and varied significantly within sites according to season. M. spinolai was not found in sites characterized by human perturbation of quarries. Our results confirm M. spinolai as a silvatic triatomine whose importance as a vector of Chagas disease will depend on contact with humans. This could occur if the habitats where populations of this species are found become exploited for the building of urban areas.

Animals↗
PubMed2001

Chagas disease prevention through improved housing using an ecosystem approach to health.

This Chagas disease prevention project via housing improvement aims to determine the efficiency of different interventions in vector control. The following study describes the target communities, disease magnitude, and housing improvements. Transmission levels are analysed from an ecological and socioeconomic perspective. Special interest was focused on the peridomicile as the origin of domiciliary reinfestation. In the original project, three intervention programs were proposed, one for each of the three communities: (a) an insecticide spraying program; (b) a housing improvement program; and (c) a combined program of spraying and housing improvement. The three communities currently have different risks of exposure to triatominae reinfestation as a consequence of the type of intervention carried out. A new multidisciplinary approach which integrates participatory, community-based research and socioeconomic dimensions will allow to determine the efficiency of models for territorial ordering, community education, and environmental interventions in Chagas disease control.

Animals↗
PubMed2001

Mitochondrial DNA sequences of triatomines (Hemiptera: Reduviidae): phylogenetic relationships.

The phylogenetic relationships among 18 species of Triatominae were inferred based on mitochondrial DNA (mtDNA) sequences. The species of Triatoma included 11 belonging to the infestans complex [T. infestans (Klug), T. guasayana Wygodzinsky & Abalos, T. sordida (Stål), T. platensis Neiva, T. brasiliensis Neiva, T. rubrovaria (Blanchard), T. vitticeps (Stål), T. delpontei Romaña & Abalos, T. maculata (Erichson), T. patagonica Del Ponte, and T. matogrossensis Leite & Barbosa] and four others of the same genus but of different complexes [T. circummaculata (Stål), T. protracta (Uhler), T. dimidiata (Latreille), and T. mazzottii Usinger]. As possible outgroups we used Mepraia spinolai Mazza, Panstrongylus megistus (Burmeister), and Rhodnius prolixus Stål. We analyzed mtDNA fragments of the 12S and 16S ribosomal RNA genes from each of the 18 species, as well as of the cytochrome oxidase I (COI) gene from nine. The 12S, 16S, and COI gene sequences were analyzed individually and combined. All of the phylogenetic analyses unambiguously supported two clusters: one including T. infestans, T. platensis, and T. delpontei, and the other T. sordida and T. mutagrossensis. Inclusion of T. circummaculata into the infestans complex was confirmed, although this is in disagreement with the morphological classification. On the other hand, our analyses showed that T. dimidiata is closely related to a phylosoma complex species, T. mazzottii. This is consistent with the tentative classification previously made based on morphological characters. The issue of the monophyly of the genus Triatoma remains unresolved.

Animals↗
PubMed1999

Mitochondrial DNA sequence variation among triatomine vectors of Chagas' disease.

Kissing bugs or triatomines (Reduviidae: Triatominae) are vectors of the Chagas' disease agent Trypanosoma cruzi. There is a current need for more sensitive tools for use in discrimination of different bug populations and species, thus allowing a better understanding of these insects as it relates to disease transmission and control. In a preliminary analysis of the mitochondrial large subunit ribosomal RNA (mtlsurRNA) and cytochrome B (mtCytB) genes, we used DNA sequencing to study species identification and phylogeny. In both examined gene regions, about 46% of nucleotide positions exhibited polymorphism. The examined region of mtCytB appears to have evolved more rapidly than the examined region of mtlsurRNA. Phylogenetic analysis of both gene fragments in the examined species produced similar results that were generally consistent with the accepted taxonomy of the subfamily. The two major tribes, Rhodniini and Triatomini, were supported, along with additional clades that corresponded to accepted species complexes within the Rhodnius and Triatoma genera. The one chief exception was that Psammolestes coreodes sorted into the Rhodnius prolixus-robustus-neglectus clade, with bootsrap values of 99% and 81%, respectively, for the mtlsurRNA and mtCytB fragments. All of the individual species examined could be distinguished at both genetic loci.

Animals↗
PubMed2006

An alternative, less invasive blood sample collection technique for serologic studies utilizing triatomine bugs (Heteroptera; Insecta).

The collection of blood samples for serological studies is often stressful for the focus animal. Recently, the use of bloodsucking bugs, such as Dipetalogaster maximus or Triatoma infestans (Reduviidae; Triatominae; Heteroptera), has been suggested as a new and less invasive method for blood collection. To evaluate this technique, we collected paired blood samples from 20 domestic rabbits (Oryctolagus cuniculus) during a study of rabbit hemorrhagic disease virus (RHDV). For each rabbit, blood samples were collected by the conventional method (needle and syringe from the vena auricularis) and through feeding by D. maximus. Samples were tested for RHDV antibodies using standard test kits at three different dilutions. Antibody titers were identical for 56 paired samples and differed in only four cases. The simple matching indices were 1 for the 1:10 dilution and 0.9 for the 1:100 and 1:1000 dilutions. The major advantages of the new technique are 1) the possibility to obtain blood from animals where veins are inaccessible and 2) the fact that anesthesia of focus animals may not be necessary.

Animals↗
PubMed2001

[A new species of the oliveirai complex (new designation for matogrossensis complex) from the State of Rio Grande do Sul, Brazil].

The authors describe a new species of Triatominae (Hemiptera, Reduviidae) from the State of Rio Grande do Sul, Brazil. The study was made with specimens captured in basaltic formations, at an average altitude of 750 m.o.s.l. The new species is included in the oliveirai complex together with other four species T. williami, T. matogrossensis, T. guazu and T. jurbergi). The new species was compared with the most similar one, T. oliveirai, from which the main differences are on the proportions of head, ante and postocular regions, the general color pattern and the male genitalia, specially on the median process of the pygophore, the support of phallosome, the vesica and the process of the endosome.

Animals↗
PubMed1991

Vector population responses to control interventions.

In 1981, Kenyan authorities attempted eradication of tsetse (Glossina pallidipes) from the Lambwe valley, by sequential aerial spraying of endosulfan. Fly populations were reduced by over 99.9% in the main habitats, but recovered to their original levels within one year. In 1986, an Argentine research team attempted local elimination of domestic Triatominae (Triatoma infestans) in an area of Santiago del Estero. House infestation rates were reduced to an apparent zero, but recovered to pre-control levels in two years. In Sri Lanka, a combination of mosquito control with active case detection and treatment reduced malaria incidence to just 17 cases in 1964. Interruption of the programme then saw case incidence return to over 500,000 by 1969. These three examples-from African trypanosomiasis, South American Chagas disease and malaria-all illustrate the same process. Vector populations, infestation rates, and rates of disease transmission, can be reduced. The real problem is not in achieving the initial reduction, but in subsequently either driving the disease to extinction or maintaining it below acceptable levels. And this problem takes us beyond the simple analysis of interventions, into the complex realms of population behaviour set in its political, social and economic context. It seems that we have been too rarely concerned to plan and implement the long term surveillance and selective interventions that are required to translate initial gains into real success. In biological terms, we tend to ignore the complexity and robustness of vector populations and disease transmission cycles, especially their varied capacity to recover from interference. Moreover, in socio-political terms, a reduced problem-even one representing potential for future catastrophe-tends to claim less priority than present problems, even though premature redeployment of resources may abnegate gains already achieved. The problem is strongly compounded by methods of economic analysis where the benefits of avoiding future problems are strongly discounted in favour of short-term temporary gains. This paper seeks to open discussion on these long-term planning issues.

Animals↗
PubMed1994

An inhibitor of collagen-induced platelet aggregation from the saliva of Triatoma pallidipennis.

The saliva of Triatoma pallidipennis, a blood-sucking triatomine bug (Hemiptera, family Reduviidae, subfamily Triatominae) was found to contain a factor that specifically inhibits collagen-induced platelet aggregation. The 19-kDa protein was purified to homogeneity and named pallidipin. Collagen-mediated aggregation of platelets in plasma and of washed platelets was inhibited with the same efficacy. No inhibition of aggregation stimulated by other effectors (ADP, thrombin, thromboxane A2 mimetic U46619, phorbol ester) was detected. Pallidipin had no effect on platelet adhesion to collagen but inhibited ATP release from platelets. It interacted reversibly with platelets and may share with collagen a common target on them. The protein exhibits a unique primary structure (predicted from cDNA clones) with no significant similarity to other previously described sequences. The protein produced in recombinant baby hamster kidney cells had antiaggregatory effects similar to those of native pallidipin. Availability of recombinant pallidipin will allow further investigation of the precise mechanism of action.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1985

Chagas' disease in pre-Columbian South America.

The quest for the origin and dispersion of Chagas' disease, the second most important vector-borne disease in Latin America, has epidemiological, immunological, and genetical implications. Conjectures based on accounts of chroniclers, reviews of the archaeological literature and the present distribution of triatomine bugs, the vectors of the disease, held that the origin of the adaptation of Triatoma infestans (a species of the subfamily Triatominae) to human dwellings occurred in prehistoric times. The autopsy of 35 mummies exhumed in the Chilean desert, dated between 470 B.C. and 600 A.D., revealed the presence of clinical manifestations of Chagas' disease and put earlier speculations on a factual basis.

Chagas Disease↗
PubMedDate not supplied

Surgery of chagasic megacolon.

Chagas' disease is an endemic clinical entity caused by Trypanosoma cruzi, a parasite that is transmitted to humans by the hematophagic Triatominae insects. It affects several million persons in Latin America, mostly in Brazil, Argentina, Chile, Paraguay, and Bolivia. Megacolon, the most common complication of intestinal trypanosomiasis, results in severe constipation, for which surgery is indicated. A variety of procedures have been proposed for the correction of this disabling condition including sigmoidectomy, abdominal rectosigmoidectomy, left colectomy, and subtotal colectomy. On long-term follow-up, however, these operations have proved to be inadequate in a significant number of cases, apparently due to preservation of the dyskinetic rectum which continues to act as a functional obstacle to the progression of the fecal bolus. On the other hand, pull-through operations, which include the removal of all or almost all of the dyskinetic rectum, or the exclusion of the rectum, as in the Duhamel-Haddad operation, have been demonstrated to be superior. The abdominoperineal endoanal pull-through resection with delayed colorectal anastomosis and the Duhamel-Haddad operation are the most accepted procedures in Brazil and other Latin American countries; their technical details are illustrated. Functional results are satisfactory. Anal continence is normal in the vast majority of cases and sexual disturbances are rare. Routine treatment of 2 main complications--fecaloma and volvulus of the sigmoid colon--are discussed.

Anastomosis, Surgical↗
PubMed2006

Cornea as a tissue reservoir of Trypanosoma cruzi.

Trypanosoma cruzi causal agent of Chagas' disease is a paninfective parasite of mammals transmitted through skin fecal contamination by Triatominae vectors. Studies of alternative routes for infection are scarce; therefore, eye infection should be important, because of the eye's high blood irrigation and brain proximity, as port of entry of the parasite. Trypanosoma cruzi parasites and/or their genetic material in ocular and adjacent muscle tissues were studied in batches of six NMRI mice (15 g) and Trichomys apereoides, an ancient caviomorph (250 g) inoculated with T. cruzi metacyclics from Brazilian (2) and Venezuelan (3) isolates genetically typified as T. cruzi I and II. Two animals/batch in the acute or chronic phase were killed and necropsies of cardiac and skeletal muscles, eyeball, and surrounding ocular muscle were processed for hematoxylin-eosine staining. Tissue parasitism was determined. DNA of the digested sections of the eyeball (5-10 mum) was extracted for T. cruzi k-DNA amplification by PCR, with S35 and S36 primers. The PCR products were analyzed. The average of maximum values of parasitemia of all infected animals was of 10(5) trypomastigotes/ml blood. Skeletal muscle and heart were colonized in patent infection for all isolates. Amastigote nests were found in corneal tissue of 2/3 of the used isolates and adjacent ocular muscle and connective tissue were parasitized. Trypanosoma cruzi k-DNA (330-bp band) was observed in ocular tissue of 4/6 of the isolates studied in both animal models. Investigations concerning infection of the eye globe tissues by T. cruzi are extremely scarce. The presence of stages of T. cruzi and/or its genetic products in ocular tissues indicate a broad colonization from a systemic infection. The results show the ocular environment as a possible appropriate microniche for T. cruzi and emphasize the risk of transmitting T. cruzi by ocular fluids and by parasitized cornea through transplants.

Animals↗