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1.
Rev. panam. salud publica ; 7(3): 162-167, Mar. 2000. ilus, tab
Artigo em Inglês | MedCarib | ID: med-16927

RESUMO

In the Limbe River valley of northern Haiti a retrospective study at the Bon Samaritain Hospital (BSH) determined the total number of cases and the cyclical nature of malaria from 1975 through 1997, examined the relationship between rainfall and malaria from 1975 through 1985, and compared the incidence of malaria at that hospital with general trends for Haiti for 1975 through 196 as reported by the World Health Organization (WHO). During 1975-1997, 27 078 positive cases of malaria were diagnosed at BSH; 50 percent of these cases occured during 16 weeks out of the year, during a summer peak in June and July and a winter peak in December and January. For 1975-1985, there was no significant correlation between the incidence of malaria and annual rainfall. The strongest correlation was observed between weekly rainfall and weekly incidence of malaria when the data was staggered to allow a lag of 9-11 weeks between rainfall and new malaria cases. The lag period is explained by the time required for the creation of breeding sites after rain, the life cycle of the Anopheles albimanus mosquito and the Plasmodium falciparum parasite, and the incubation period for falciparum malaria. The incidence of malaria in the Limbe valley loosely followed the trends in all of Haiti and also supported WHO reports indicating that malaria in Haiti has been in a general decline since the mid-1980s. By showing the seasonal trends for malaria in the Limbe valley and the relationship between rainfall and malaria over an extended time period, this study provides a means to measure the effectiveness of malaria control efforts in the region (AU)


Assuntos
Humanos , Malária/epidemiologia , Haiti , Vetores de Doenças , Plasmodium falciparum , Anopheles
2.
Artigo em Inglês | MedCarib | ID: med-17600

RESUMO

This study investigated the sensitivity of the malaria surveillance system in Trinidad. Based on the number of cases (67) detected between 1989 and 1998 by hospital and commercial laboratories (HCL), the number (117) detected by active case detection by the Insect Vector Control Division (IVCD) during the same period, and the number detected by both (117; one further case self-reported), it was calculated that there were 3 undiagnosed cases (95% confidence interval 0-6) during the period concerned - HCL detected 55.4% of cases and the IVCD 97.5%. The characteristics of the 118 cases (of which 40 were transmitted in 2 outbreaks in Trinidad and the rest imported) are summarized in a table.


Assuntos
Animais , Humanos , Malária , Controle de Vetores de Doenças , Anopheles , Trinidad e Tobago
3.
Ann Trop Med Parasitol ; 93(5): 467-75, July 1999.
Artigo em Inglês | MedCarib | ID: med-739

RESUMO

A focus of Plasmodium malariae infection has recently occurred on the island of Trinidad, some 30 years after a successful eradiction programme. Examination of bloodsmears revealed 22 cases of P. malariae in the Nariva-Mayaro area of Trinidad between August 1994 and September 1995. Most (77 percent) of the cases were male and, as seven were aged >25 years of age, it appeared that transmission had been renewed, probably by the vector Anopheles bellator. However, none of the 3000 mosquitoes tested by ELISA for circumsporozoite protein of P. malariae proved positive. Use of IFAT to check blood samples for P. malariae appeared more sensitive than direct examination of bloodsmears, indicating that 42 (13 percent) of the 325 samples tested were seropositive (at titres of 1:256 or greater). The levels of transmission of the parasite may therefore be even higher than indicated by examination of blood smears. The surveillance measurers adopted to understand the epidemiology of this outbreak of P. malariae in Trinidad are described. The need to maintain malaria surveillance in all the countries where P. malariae parasites once existed (prior to eradication) is emphasised. (AU)


Assuntos
Adulto , Idoso , 21003 , Adolescente , Criança , Pré-Escolar , Feminino , Humanos , Masculino , Recém-Nascido , Lactente , Pessoa de Meia-Idade , Plasmodium malariae , Surtos de Doenças , Malária/epidemiologia , Anopheles/parasitologia , Análise por Conglomerados , Seguimentos , Insetos Vetores/parasitologia , Plasmodium malariae/isolamento & purificação , Trinidad e Tobago/epidemiologia
4.
J Vector Ecol ; 24(1): 83-90, Jun. 1999.
Artigo em Inglês | MedCarib | ID: med-1321

RESUMO

Diel oviposition patterns of Anopheles bellator were determined for field collected females from platanal forest, Cumaca, Trinidad. The time of oviposition and number of eggs laid were monitored at two-hour intervals for a set of 30 individual females and a group of 120 females. Individual females of An. bellator displayed bimodal nocturnal patterns of oviposition. During the first gonotrophic cycle, two waves of oviposition occurred between 1600 and 2400 h (80.9 percent of eggs laid; 78 percent of occurrences) and between 0200 and 0600 h (19.1 percent of eggs laid; 22 percent of occurrences). During the second gonotrophic cycle the oviposition pattern was similar to that observed during the first gonotrophic cycle, except that oviposition ended at 0400 h rather than at 0600 h. A similar oviposition pattern was observed among the 120 caged adults as found during the second gonotrophic cycle of individual females. The length of the gonotrophic cycle ranged from 57 to 120 hours (means 72.3 hours) for the first gonotrophic cycle and from 61 to 78 hours (means 70.3 hours) for the second cycle. The fecundity of An. bellator averaged 56.6 +/- 25.0 (range 13 to 101 eggs) and 39.3 +/- 13.3 (range 23 to 59 eggs) for the first and second gonotrophic cycle, respectively. Females survived in the laboratory for a maximum of 19 days. These observations on An. bellator oviposition patterns are the first to be described and may be useful for future attempts at colonization.(AU)


Assuntos
21003 , Feminino , Anopheles/fisiologia , Ritmo Circadiano , Oviposição , Fertilidade , Trinidad e Tobago
5.
Am J Trop Med Hyg ; 60(3): 364-76, Mar. 1999.
Artigo em Inglês | MedCarib | ID: med-1345

RESUMO

A genetic and morphologic survey of Anopheles darlingi populations collected from seven countries in Central and South America was performed to clarify the taxonomic status of this major malaria vector species in the Americas. Population genetics was based on three techniques including isozyme, random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR), and internal transcribed spacer 2 (ITS2) markers. The results of the isozyme analysis indicated moderate differences in the allele frequencies of three putative loci (glutamate oxalaoacetate transaminase-1, isocitrate dehydrogenase-1, and phosphoglucomutase) of the 31 analyzed. No fixed electromorphic differences separated the populations of An. darlingi, which showed little genetic divergence (Nei distances = 0.976-0.995). Fragments produced by RAPD-PCR demonstrated evidence of geographic partitioning and showed that all populations were separated by small genetic distances as measured with the 1 - S distance matrix. The ITS2 sequences for all samples were identical except for four individuals from Belize that differed by a three-base deletion (CCC). The morphologic study demonstrated that the Euclidean distances ranged from 0.02 to 0.14, with the highest value observed between populations from Belize and Bolivia. Based on these analyses, all the An. darlingi populations examined demonstrated a genetic similarity that is consistent with the existence of a single species and suggest that gene flow is occurring throughout the species' geographic range.(Au)


Assuntos
21003 , Feminino , Anopheles/classificação , Insetos Vetores/classificação , Malária/transmissão , Sequência de Bases , Belize , Eletroforese em Gel de Amido/veterinária , Anopheles/enzimologia , Anopheles/genética , Insetos Vetores/enzimologia , Insetos Vetores/genética , Isocitrato Desidrogenase/química , Isoenzimas/análise , Dados de Sequência Molecular , Fosfoglucomutase/química , Filogenia , Reação em Cadeia da Polimerase/veterinária , Técnica de Amplificação ao Acaso de DNA Polimórfico/veterinária , Análise de Sequência de DNA , América do Sul
6.
Surinaams Medisch Bulletin ; 13(3): 2-14, Nov.1998. tab
Artigo em Inglês | MedCarib | ID: med-1086

RESUMO

Review of the vector status and investigations on An.aquasalis in Guyana was undertaken. The data revealed that the incrimination of aquasalis in malaria transmission was largely circumstancial and that the actual possiblity for such transmission, even within optimal conditions, may be very low.....(AU)


Assuntos
Humanos , Anopheles , Guiana/epidemiologia
7.
Mem Inst Oswaldo Cruz ; 93(5): 647-50, Sept.-Oct. 1998.
Artigo em Inglês | MedCarib | ID: med-1354

RESUMO

A new phylogenetic analysis of the Nyssorhynchus subgenus (Danoff-Burg and Conn, unpub. data) using six data sets morphological (all life stages); scanning electron micrographs of eggs; nuclear ITS2 sequences; mitochondrial COII, ND2 and ND6 sequences) revealed different topologies when each data set was analyzed separately but no heterogeneity between the data sets using the arn test. Consequently, the most accurate estimate of the phylogeny was obtained when all the data were combined. This new phylogeny supports a monophyletic Nyssorhynchus subgenus but both previously recognized sections in the subgenus (Albimanus and Argyritarsis) were demonstrated to be paraphyletic relative to each other and four of the seven clades inclueded species previously placed in both sections. One of these clades included both Anopheles darlingi and An. albimanus, suggesting that the ability to vector malaria effectively may have originated once in this subgenus. Both a conserved (315 bp) and a variable (425 bp) region of the mitochondrial COI gene from 15 populations of An. darlingi from Belize, Bolivia, Brazil, French Guiana, Peru and Venezuela were used to examine the evolutionary history species and to test several analytical assumptions. Results demonstrated (1) parsimony analysis is equally informative compared to distance analysis NJ; (2) clades or clusters are more strongly supported when these two regions are combined compared to either region separately; (3) evidence (in the form of remnants of older haplotype lineages) for two colonization events; and (4) significant genetic divergence within the population from Peixoto de Azevedo (State of Mato Grosso, Brazil. The oldest lineage includes populations from Peixoto, Boa Vista (State of Roraima) and Dourado (State of Sao Paulo).(AU)


Assuntos
21003 , Estudo Comparativo , Anopheles/classificação , Anopheles/genética , Genética Populacional , Filogenia , América , Estágios do Ciclo de Vida
8.
St. George's; WINDREF; 1998. 12 p. tab, gra. (FULLTEXT).
Monografia em Inglês | MedCarib | ID: med-16207

RESUMO

Malaria was eradicated from Grenada in 1962 and the island has since remained free of the disease. The resurgence of malaria in endemic areas, as well as in countries where it had been previously eradicated, provided the impetus for a study to assess the risk of the re-introduction and re-establishment of malaria in Grenada. This study surveyed the recorded historical breeding sites of Anopheles spp in Grenada between April 1996 and April 1997, thereby encompassing two dry seasons and one wet season. Although the threat of imported cases of malaria into Grenada has never been greater since the eradication of the disease, the results of this study indicate that the re-establishment of malaria as a serious public health problem is less likely. The unfamiliarity of diagnosis of malaria in this malaria free country, coupled with the presence of the vectors, however, mandates that malaria surveillance must be maintained, particularly since the government's spending on vector control activities has been reduced over the years


Assuntos
Anopheles , Malária/epidemiologia , Granada/epidemiologia
9.
J Am Mosq Control Assoc ; 12(3): 402-5, Sept. 1996.
Artigo em Inglês | MedCarib | ID: med-2492

RESUMO

The diel oviposition periodicity of wild-caught Anopheles oswaldoi collected from the forest-ecotone habitat in Valencia, Trinidad, was studied in the laboratory by recording the performance of egg-laying individuals and a colony at 2-h intervals. Oviposition was almost exclusively nocturnal, with 95.3 percent of eggs and 91.3 percent of oviposition occurrences being observed during the scotophase. During the rest of the day, only 4.7 percent of eggs (8. 7 percent ocurrences) were recorded after dawn (0600-0800 h). Wild caught females engorged on human blood under laboratory conditions matured, on average, 61.1 +/- 32.3 follicles 9range 56-135). Ranges of 50-69, 70-89, 90-109, and > 110 follicles were matured by 12, 4, 4, and 3 gravid females, respectively. These findings provide vector operators with a window of time to maximize the impact of insecticides on An oswaldoi populations. (Au)


Assuntos
21003 , Feminino , Humanos , Anopheles/fisiologia , Ritmo Circadiano , Fertilidade , Controle de Mosquitos , Oviposição , Trinidad e Tobago
10.
Am J Trop Med Hyg ; 54(3): 304-8, Mar. 1996.
Artigo em Inglês | MedCarib | ID: med-3515

RESUMO

Use of multispectral satellite data to predict arthropod-borne disease trouble spots is dependent on clear understandings of environmental factors that determine the presence of disease vectors. A blind test of remote sensing - based predictions for the spatial distribution of a malaria vector, Anopheles pseudopunctipennis, was conducted as a follow-up to two years of studies on vector-environmental relationships in Belize. Four of eight sites that were predicted to be high probability locations for presence of An. pseudopunctipennis were positive and all low probability site (0 of 12) were negative. The absence of An. pseudopunctipennis at four high probability locations probably reflects the low densities that seem to characterize field populations of this species, i.e., the population densities were below the threshold of our sampling effort. Another important malaria vector. An. darlingi, was also present at all high probability sites and absent at all low probability sites. Anopheles darlingi, like An. pseudopunctipennis, is a riverine species. Prior to these collections at ecologically defined locations, this species was last detected in Belize in 1946 (AU)


Assuntos
21003 , Feminino , Anopheles/fisiologia , Insetos Vetores/fisiologia , Malária/transmissão , Belize , Análise Discriminante , Água Doce , Geografia , Processamento de Imagem Assistida por Computador , Probabilidade , Comunicações Via Satélite
11.
s.l; [American Mosquito Control Association Inc.]; 1996. 402-5 p. tab., 3
Monografia em Inglês | MedCarib | ID: med-16262

RESUMO

The diel oviposition periodicity of wild-caught Anopheles oswaldoi collected from the forest-ecotone habitat of Valencia, Trinidad, was studied in the laboratory by recording the performance of of egg-laying individuals and a colony at 2-h intervals. Oviposition was almost exclusively nocturnal, with 95.3 percent of eggs and 91.3 percent of oviposition occurences being observed during the scotophase. During the rest of the day, only 4.7 percent of eggs (8.7 percent occurences) were recorded after dawn (0600-0800 h). Wild-caught females engorged on human blood under laboratory conditions matured, on average, 61.1 +/- 32.3 follicles (range 56-135). Ranges of 50-69, 70-89, 90-109, and >110 follicles were matured by 12, 4, 4, and 3 gravid females, respectively. These findings provide vector operators with a window of time to maximize the impact of insecticides on An. oswaldoi populations (AU)


Assuntos
Anopheles , Oviposição , Fertilização , Insetos Vetores , Trinidad e Tobago
12.
[Oxon]; [CAB International]; 1996. 351-4 p. ilus.
Monografia em Inglês | MedCarib | ID: med-16273

RESUMO

The cibarial armatures of Anopheles albitarsis Lynch Arribalzaga, A. aquasalis Curry, A. bellator Dyar & Knab and A. homunculus Komp are described for the first time. Ten to 15 minutes after blood feeding, higher levels of blood haemolysis were observed among A. bellator (14.9 percent) and A. homunculus (14 percent) mosquitoes which possessed type C cibarial armatures than among A. albitarsis (3.3 percent) and A. aquasalis (3.2 percent) which possessed type B cibarial armatures. In contrast, there were no significant differences among the four species in levels of extra-erythrocytic haemolysis when measured immediately after one hour. The blood processing physiology observed for the four anopheline species is discussed at the enzymatic, mechanical and taxonomic levels as it relates to innate vector competence (AU)


Assuntos
Anopheles/fisiologia , Trinidad e Tobago , Sistema Digestório/anatomia & histologia , Comportamento Alimentar , Trinidad e Tobago
13.
Am J Trop Med Hyg ; 53(5): 482-8, Nov. 1995.
Artigo em Inglês | MedCarib | ID: med-3514

RESUMO

Remote sensing is particularly helpful for assessing the location and extent of vegetation formations, such as herbaceous wetlands, that are difficult to examine on the ground. Marshes that are sparsely populated with emergent macrophytes and dense cyanobacterial mats have previously been identified as very productive Anopheles albimanus larval habitat. This type of habit was detectable on a classified multispectral Systeme Probatoire d'Observation de la Terre image on northern Belize as a mixture of two isoclasses. A similar spectral signature is characteristic for vegetation of river margin consisting of aquatic grasses and water hyacinth, which constitutes another productive larval habitat. Based on the distance between human settlements (sites) of various sizes and the nearest marsh/river exhibiting this particular class combination, we selected two groups of sites; those located closer than 500 m and those located more than 1,500 m from such habitats. Based on previous adults collections near larval habitats, we defined a landing rate of 0.5 mosquitoes/human/min from 6:30 pm to 8: pm as the threshold for high (o 0.5 mosquitoes/human/min) versus low (05 mosquitoes/human/min) densities of An. albimanus. Sites located less than 500 m from the habitat were predicted as having values higher than this threshold, while lower values were predicted for sites located greater than 1,500 m from the habitat. Preditions were verified by collections of mosquitoes landing on humans. The predictions were 100 percent accurate for sites in the > 1,500-m category and 89 percent accurate for sites in the < 500-m category (AU)


Assuntos
21003 , Humanos , Anopheles/fisiologia , Insetos Vetores/fisiologia , Belize , Processamento de Imagem Assistida por Computador , Larva/fisiologia , Modelos Logísticos , Malária/prevenção & controle , Malária/transmissão , Características de Residência , Software
14.
Am J Trop Med Hyg ; 53(5): 482-8, 1995. ilus, maps, tab
Artigo em Inglês | MedCarib | ID: med-3601

RESUMO

Remote sensing is particularly helpful for assessing the location and extent of vegetation formations such as herbaceous wetlands, that are difficult to examine on the ground. Marshes that are sparsely populated with emergent macrophytes and dense cyanobacterial mats have previously been identified as very productive Anopheles albimanus larval habitats. This type of habitat was detectable on a classified multispectral Systeme Probatoire d'Observation de la Terre image of northern Belize as a mixture of two isoclasses. A similar spectral signature is characteristic for vegetation of river margins consisting of aquatic grasses and water hyacinth, which constitutes another larval habitat. Based on the distance between human settlements (sites) of various sizes and the nearest marsh/river exhibiting this particular class combination, we selected two groups of sites: those located closer than 500 m and those located more than 1,500 m from such habitats. Based on previous adult collections near larval habitats, we defined a landing rate of 0.5 mosquitoes/human/min from 6:30 p.m. to 8:00 p.m. as the threshold for high (o 0.5 mosquitoes/human/min) versus low (< 0.5 mosquitoes/human/min) densities of An. albimanus. Sites located less than 500 m from the habitat were predicted as having values higher than this threshold, while lower values were predicted for sites located greater that 1,500 m from the habitat. Predictions were verified by collections of mosquitoes landing on humans. The predictions were 100 percent accurate for the sites in the > 1,500-m category and 89 percent accurate for sites in the > 500-m category(AU)


Assuntos
21003 , Humanos , Anopheles/fisiologia , Insetos Vetores/fisiologia , Belize , Processamento de Imagem Assistida por Computador , Larva/fisiologia , Modelos Logísticos , Malária/prevenção & controle , Malária/transmissão , Características de Residência
15.
s.l; American Mosquito Control Association; 1995. 103-6 p. ilus., 1
Monografia em Inglês | MedCarib | ID: med-16265

RESUMO

The diel pattern of oviposition of wild-caught Anopheles albitarsis derived from rice fields in Frederick Settlement, Trinidad, was studied in the laboratory by recording the performance of egg-laying individuals and a colony at 2-h intervals. Oviposition was almost exclusively nocturnal, with 79.3 percent of the eggs being laid during the scotophase. During the rest of the day and during evening twilight, 7.8 and 12.9 percent eggs were laid, respectively. Wild-caught parous females allowed to engorge on human blood matured, on average, 7.1 +/- 12.4 follicles (range 53-106). These findings provide vector control personnel with the opportunity to maximize the impact of insecticides on An. albitarsis populations by restricting their operations to the time of peak activity (AU)


Assuntos
Anopheles , Trinidad e Tobago , Oviposição/fisiologia , Paridade/fisiologia
16.
s.l; [Liverpool School of Tropical Medicine]; 1995. 539-40 p. ilus., 5
Monografia em Inglês | MedCarib | ID: med-16283
18.
Parassitologia ; 36: 175-95, 1994.
Artigo em Inglês | MedCarib | ID: med-3604

RESUMO

The article analyses the evolution of knowledge and rationale of control of a special case of malaria transmission based on Bromelia-Kerteszia complex. Since bromeliaceae function as a 'host of the carrier' and were previously associated with natural forests, the elucidation of bromeliad malaria historically elicited controversies concerning the imputation of Kerteszaie as transmitters as well as over control strategies directed to bromelia eradication (manual removal, herbicides and deforestation), use of insecticides and chemoprophylaxis. Established authority, disciplinary traditions, conceptual premises and contemporary criteria for validating knowledge in the field partly explain the long time gap since Adolpho Lutz announced as the beginning of the century the existence of a new mosquito and breeding site as responsible for a 'forest malaria' epidemic occurring at a high altitude. The article brings attention to how economic, political and institutional determinants played an important role in redefining studies that led both in Trinidad and Brazil to the recognition of the importance of kerteszia transmission, including urban areas, and establishing new approaches to its study, most relevant of all the concurrence of broad ecological research. The article then describes the Brazilian campaign strategies which showed significant short-term results but had to wait four decades to achieve the goal of eradication due to the peculiar characteristics of this pathogenic complex. Finally, it brings attention to the importance of encompassing social values and discourses, in this case, environmental preservation, to understanding historical trends of malaria control programs(AU)


Assuntos
21003 , HISTORY OF MEDICINE, 20TH CENT , Humanos , Culicidae/parasitologia , Malária/história , Plantas/parasitologia , Anopheles/parasitologia , Brasil , Ecologia , Malária/prevenção & controle , Malária/transmissão , Trinidad e Tobago
19.
J Am Mosq Control Assoc ; 10(4): 522-26, 1994. ilus, tab
Artigo em Inglês | MedCarib | ID: med-3637

RESUMO

Seasonal abundance, daily biting activity, and the age composition of adult Anopheles homunculus female populations were monitored weekly during 1989-90 by human bait on the ground at Cumaca Forest, Platanal, Trinidad. Landing collections of An. homunculus showed diurnal and nocturnal activity, with a single peak between 1600 and 2000 hours. Overall, 27.7 percent of An. homunculus were collected during the dry season and 72.3 percent during the wet season. Similar seasonal parous rates were observed in wet (58.9 percent) and dry (56.1 percent) seasons. Diel periodicities of nullipars and pars were almost identical during the wet and dry seasons(AU)


Assuntos
21003 , Feminino , Humanos , Anopheles/fisiologia , Comportamento Alimentar , Paridade , Mordeduras e Picadas de Insetos , Periodicidade , Vigilância da População , Estações do Ano , Trinidad e Tobago
20.
s.l; American Mosquito Control Association; 1994. 522-6 p. ilus., 4
Monografia em Inglês | MedCarib | ID: med-16269

RESUMO

Seasonal abundance, daily biting activity, and the age composition of adult Anopheles homunculus female populations were monitored weekly during 1989-90 by human bait on the ground at Cumaca Forest, Platanal, Trinidad. Landing collections of An. homunculus showed diurnal and nocturnal activity, with a single peak between 1600 and 2000 hours. Overall, 27.7 percent of An. homunculus were collected during the dry season and 72.3 percent during the wet season. Similiar seasonal parous rates were observed in wet (58.9 percent) and dry (56.1 percent) seasons. Diel periodicities of nullipars and pars were almost identical during the wet and dry seasons (AU)


Assuntos
Adulto , Humanos , Anopheles , Trinidad e Tobago , Cruzamento , Trinidad e Tobago , Paridade , Trinidad e Tobago , Mordeduras e Picadas de Insetos/epidemiologia , Trinidad e Tobago
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