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Anopheline species, some of their habits and relation to malaria in endemic areas of Rond?nia State, Amazon region of Brazil
Louren?o-de-Oliveira, Ricardo;Guimar?es, Anthony Erico da Gama;Arlé, Monique;Silva, Tereza Fernandes da;Castro, Márcia Gon?alves;Motta, Monique Albuquerque;Deane, Leonidas M.;
Memórias do Instituto Oswaldo Cruz , 1989, DOI: 10.1590/S0074-02761989000400008
Abstract: in view of recent studies incriminating several species of anophelines, besides anopheles darlingi, as malaria vectors in the brazilian amazon, we performed an anopheline survey in four localities - ariquemes, cujubim, machadinho and itapo? do oeste - in rond?nia, the most malarious state in the country. twenty species were found. an. darlingi was, by far, the dominant species and the only one whose density coincided with that of malaria. on human baits it was more numerous in the immediate vincinity of houses than indoors whre, however, it was almost the only species encountered. on both situations it fed mostly at sunset and during the first half of the night. it was less numerous far from houses and scarce inside the forest. other species (an. triannulatus, an. evansae, an. albitarsis, an. strodei) appeared in appreciable numbers only in ariquemes, both in areas with and without malaria. the remaining species were scanty. an. darlingi was confirmed as the primary local vector.
Intrapopulational genetic differentiation in Anopheles (N.) darlingi Root, 1926 (Diptera: Culicidae) in the amazon region
Santos, Joselita Maria Mendes dos;Lobo, Jorge Arturo;Tadei, Wanderli Pedro;Contel, Eucleia P. Betioli;
Genetics and Molecular Biology , 1999, DOI: 10.1590/S1415-47571999000300007
Abstract: four natural amazonian anopheles darlingi populations were analyzed for 19 loci, 12 of which showed variation, i.e., 68.4% of polymorphic loci. the ariquemes, rond?nia, population was the most variable, with a large number of alleles per locus (2.26 ± 0.27) and high polymorphism (p = 63.15). the highest values of observed and expected intralocus heterozygosity were observed in the manaus, amazonas, population (ho = 0.432 ± 0.11; he = 0.375 ± 0.08), and the lowest in the cachoeira porteira, pará, population (ho = 0.236 ± 0.09; he = 0.290 ± 0.11). wright's f-statistic revealed disequilibrium caused by an excess of homozygotes, as shown by the fis > fst values (fis = 0.083 > 0.026) reflecting intrapopulational differentiation. the four populations studied were genetically similar, as indicated by distance and similarity values. chromosomal variation of amazon population also did not indicate geographical differentiation, and populations in the central region of the amazon basin showed high polymorphism in relation to the marginal populations, which were mainly monomorphic.
Intrapopulational genetic differentiation in Anopheles (N.) darlingi Root, 1926 (Diptera: Culicidae) in the amazon region  [cached]
Santos Joselita Maria Mendes dos,Lobo Jorge Arturo,Tadei Wanderli Pedro,Contel Eucleia P. Betioli
Genetics and Molecular Biology , 1999,
Abstract: Four natural Amazonian Anopheles darlingi populations were analyzed for 19 loci, 12 of which showed variation, i.e., 68.4% of polymorphic loci. The Ariquemes, Rond nia, population was the most variable, with a large number of alleles per locus (2.26 ± 0.27) and high polymorphism (P = 63.15). The highest values of observed and expected intralocus heterozygosity were observed in the Manaus, Amazonas, population (Ho = 0.432 ± 0.11; He = 0.375 ± 0.08), and the lowest in the Cachoeira Porteira, Pará, population (Ho = 0.236 ± 0.09; He = 0.290 ± 0.11). Wright's F-statistic revealed disequilibrium caused by an excess of homozygotes, as shown by the Fis > Fst values (Fis = 0.083 > 0.026) reflecting intrapopulational differentiation. The four populations studied were genetically similar, as indicated by distance and similarity values. Chromosomal variation of Amazon population also did not indicate geographical differentiation, and populations in the central region of the Amazon Basin showed high polymorphism in relation to the marginal populations, which were mainly monomorphic.
Infection of Anopheles darlingi fed on patients infected with Plasmodium vivax before and during treatment with chloroquine plus primaquine in Costa Marques, Rond?nia, Brazil
Klein, Terry A.;Tada, Mauro S.;Lima, Jose B. P.;Tang, Amazonia Toda;
Memórias do Instituto Oswaldo Cruz , 1992, DOI: 10.1590/S0074-02761992000200004
Abstract: five patients with asexual and sexual parasites of plasmodium vivax were treated orally with 600 mg chloroquine diphosphate (hour 0) followed with 300 mg at 8, 24 and 48 h later. primaquine phospate, 15 mg, was administered concurrently at h 0 and 24 h intervals for 14 days. anopheles darlingi were fed before the first dose (h-0.5) and 0.5, 1, 2, 4, 6, 8, 10, 12, 16, 20, 24, 36, 48, 60 and 72 h later. mosquitoes were examined for oocysts on day 8 and for sporozoites on day 15 after infection. four of the five patients studied were still infective to mosquitoes from 1-5 h after the first dose of chloroquine plus primaquine. one of these and one other patient, who vomited 15 min after the first dose, became inffective again at hours 10 and 12, respectively. once produced, oocysts in mosquitoes fed on patients before, during and after chloroquine plus primaquine treatment appeared normal and produced sporozoite infected salivary glands. in view of these data , it is concluded that primaquine demonstrated rapid gametocytocidal activity and should be administred concurrently with chloroquine to reduce vivax malaria transmission.
Endemias e epidemias na Amaz?nia: malária e doen?as emergentes em áreas ribeirinhas do Rio Madeira. Um caso de escola
Katsuragawa, Tony Hiroshi;Gil, Luiz Herman Soares;Tada, Mauro Shugiro;Silva, Luiz Hildebrando Pereira da;
Estudos Avan?ados , 2008, DOI: 10.1590/S0103-40142008000300008
Abstract: the authors present a short review on the evolution of malaria incidence in the brazilian amazon, with particular reference to the rond?nia state and the municipality of porto velho, where dramatic epidemics of malaria and other tropical diseases have been registered in the past. next, they analyze the present endemic malaria situation in the madeira river valley where two important hydroelectric power plants will be constructed in the localities of santo ant?nio and jirau. longitudinal surveys performed in the last four years in this area allow to demonstrate a high prevalence of symptomatic and asymptomatic malaria carriers in the area, associated to the presence of high densities of the malaria vector anopheles darlingi all over the year. these elements are correlated to the expected arrival of a large number of human migrants originated from non endemic areas of rond?nia and other brazilian states, attracted by the possibility of jobs in the hydroelectric power plants and by secondary opportunities in commerce, leisure, education and domestic activities. these associations create favorable conditions for malaria outbreaks and other tropical diseases that must be avoided by the establishment of additional control measures, in particular in the sanitation domain
Population genetic structure of the major malaria vector Anopheles darlingi (Diptera: Culicidae) from the Brazilian Amazon, using microsatellite markers
Scarpassa, Vera Margarete;Conn, Jan E;
Memórias do Instituto Oswaldo Cruz , 2007, DOI: 10.1590/S0074-02762007005000045
Abstract: the population genetic structure of anopheles darlingi, the major human malaria vector in the neotropics, was examined using seven microsatellite loci from nine localities in central and western amazonian brazil. high levels of genetic variability were detected (5-25 alleles per locus; he = 0.519-0.949). there was deviation from hardy-weinberg equilibrium for 59.79% of the tests due to heterozygote deficits, while the analysis of linkage disequilibrium was significant for only two of 189 (1.05%) tests, most likely caused by null alleles. genetic differentiation (fst = 0.001-0.095; nm = 4.7-363.8) indicates that gene flow is extensive among locations < 152 km apart (with two exceptions) and reduced, but not absent, at a larger geographic scale. genetic and geographic distances were significantly correlated (r2 = 0.893, p < 0.0002), supporting the isolation by distance (ibd) model. the overall estimate of ne was 202.4 individuals under the linkage disequilibrium model, and 8 under the heterozygote excess model. analysis of molecular variance showed that nearly all variation (~ 94%) was within sample locations. the upgma phenogram clustered the samples geographically, with one branch including 5/6 of the state of amazonas localities and the other branch the acre, rond?nia, and remaining amazonas localities. taken together, these data suggest little genetic structure for an. darlingi from central and western amazonian brazil. these findings also imply that the ibd model explains nearly all of the differentiation detected. in practical terms, populations of an. darlingi at distances < 152 km should respond similarly to vector control measures, because of high gene flow.
Anti-Anopheles darlingi saliva antibodies as marker of Plasmodium vivax infection and clinical immunity in the Brazilian Amazon
Bruno Andrade, Bruno Rocha, Antonio Reis-Filho, Luís Camargo, Wanderli Tadei, Luciano Moreira, Aldina Barral, Manoel Barral-Netto
Malaria Journal , 2009, DOI: 10.1186/1475-2875-8-121
Abstract: Adult volunteers from communities in the Rond?nia State, Brazil, were screened in order to assess the presence of P. vivax infection by light microscopy and nested PCR. Non-infected volunteers and individuals with symptomatic or symptomless infection were randomly selected and plasma collected. An. darlingi salivary gland sonicates (SGS) were prepared and used to measure anti-saliva antibody levels. Plasma interleukin (IL)-10 and interferon (IFN)-γ levels were also estimated and correlated to anti-SGS levels.Individuals infected with P. vivax presented higher levels of anti-SGS than non-infected individuals and antibody levels could discriminate infection. Furthermore, anti-saliva antibody measurement was also useful to distinguish asymptomatic infection from non-infection, with a high likelihood ratio. Interestingly, individuals with asymptomatic parasitaemia presented higher titers of anti-SGS and lower IFN-γ/IL-10 ratio than symptomatic ones. In P. vivax-infected asymptomatic individuals, the IFN-γ/IL-10 ratio was inversely correlated to anti-SGS titers, although not for while in symptomatic volunteers.The estimation of anti-An. darlingi antibody levels can indicate the probable P. vivax infection status and also could serve as a marker of disease severity in this region of Brazilian Amazon.Malaria continues to be one of the most serious public health problems worldwide, exacting a huge impact on human wellbeing, mainly in tropical and subtropical countries. A better understanding of the interactions between the host, the vector and the parasite could be valuable to indicate future strategies. In endemic regions, residents are frequently bitten by both uninfected and infected mosquitoes. There is also a progressive acquisition of immunity, leading to a decreased number of malaria clinical attacks related to increasing age and time residing in the endemic area [1,2]. Within the Brazilian Amazon, and mainly in riverine communities, the prevalence of asymptomatic ma
Survivorship of Anopheles darlingi (Diptera: Culicidae) in Relation with Malaria Incidence in the Brazilian Amazon  [PDF]
Fábio Saito Monteiro de Barros,Nildimar Alves Honório,Mércia Eliane Arruda
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0022388
Abstract: We performed a longitudinal study of adult survival of Anopheles darlingi, the most important vector in the Amazon, in a malarigenous frontier zone of Brazil. Survival rates were determined from both parous rates and multiparous dissections. Anopheles darlingi human biting rates, daily survival rates and expectation of life where higher in the dry season, as compared to the rainy season, and were correlated with malaria incidence. The biting density of mosquitoes that had survived long enough for completing at least one sporogonic cycle was related with the number of malaria cases by linear regression. Survival rates were the limiting factor explaining longitudinal variations in Plasmodium vivax malaria incidence and the association between adult mosquito survival and malaria was statistically significant by logistic regression (P<0.05). Survival rates were better correlated with malaria incidence than adult mosquito biting density. Mathematical modeling showed that P. falciparum and P. malariae were more vulnerable to changes in mosquito survival rates because of longer sporogonic cycle duration, as compared to P. vivax, which could account for the low prevalence of the former parasites observed in the study area. Population modeling also showed that the observed decreases in human biting rates in the wet season could be entirely explained by decreases in survival rates, suggesting that decreased breeding did not occur in the wet season, at the sites where adult mosquitoes were collected. For the first time in the literature, multivariate methods detected a statistically significant inverse relation (P<0.05) between the number of rainy days per month and daily survival rates, suggesting that rainfall may cause adult mortality.
Integrated vector management targeting Anopheles darlingi populations decreases malaria incidence in an unstable transmission area, in the rural Brazilian Amazon  [cached]
Martins-Campos Keillen M,Pinheiro Waléria D,Vítor-Silva Sheila,Siqueira André M
Malaria Journal , 2012, DOI: 10.1186/1475-2875-11-351
Abstract: Background Studies on vector behaviour should be conducted in order to evaluate the effectiveness of vector control measures on malaria protection in endemic areas of Latin America, where P. vivax predominates. This work aims to investigate the fauna of anopheline mosquitoes and verify the impact of integrated vector management in two colonization projects in the Careiro Municipality, Western Brazilian Amazon. Methods Four mosquitoes’ captures were carried out from August 2008 to March 2010, with an interval of six months between each collection. Since September 2009 a large programme to reduce the burden of malaria has started in the two communities by distribution of insecticide-treated bed nets (ITN) and intensification of indoor residual spraying (IRS). Human biting rates (HBRs), entomological inoculation rates (EIRs), malaria incidence rate (MIR) and Plasmodium carrier’s prevalence were used as outcomes to estimate the impact of the control measures. Results A total of 3,189 anophelines were collected, belonging to 13 species. Anopheles darlingi was the predominant species in the period (42.6%), followed by Anopheles albitarsis (38.4%). An. darlingi HBRs showed a notable decreasing trend from the start to the end of the study. Conversely, An. albitarsis increased its contribution to overall HBRs throughout the study. For An. darlingi there was a significant positive correlation between HBRs and MIR (p = 0.002). Anopheles albitarsis HBRs showed a significant negative correlation with the corresponding MIR (p = 0.045). EIR from total anophelines and from An. darlingi and An. albitarsis presented decreasing patterns in the successive collections. Four species of anophelines (An. darlingi, An. albitarsis, Anopheles braziliensis and Anopheles nuneztovari) were naturally infected with Plasmodium, albeit at very low infection rates. There were a decrease in the MIR for both vivax and falciparum malaria and in the prevalence of Plasmodium vivax and Plasmodium falciparum carriers during the period of study. Conclusions There is strong evidence of association between the density of An. darlingi and the incidence of malaria in the studies sites, further highlighting the importance of this vector in malaria transmission in this region. An. darlingi susceptibility to control using ITN and IRS is likely to be high in the rural settlements studied.
How prevalent is Plasmodium malariae in Rond?nia, Western Brazilian Amazon?
Cavasini, Marisa Torres Vidal;Ribeiro, Weber Luidi;Kawamoto, Fumihiko;Ferreira, Marcelo Urbano;
Revista da Sociedade Brasileira de Medicina Tropical , 2000, DOI: 10.1590/S0037-86822000000500011
Abstract: we have compared results of plasmodium species identification obtained with conventional on-site microscopy of giemsa-stained thick smears (gts) and a semi-nested polymerase chain reaction (pcr) in 96 malaria patients from rond?nia, western brazilian amazon. mixed-species infections were detected by pcr in 30% patients, but no such case had been found on gts. moreover, p. malariae infections were detected in 9 of 96 patients (10%) by pcr, but were not identified by local microscopists. the potential impact of species misidentification on malaria treatment and control is discussed.
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