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Search Results: 1 - 10 of 401966 matches for " Janine M. Ramsey "
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Gametocitos de Plasmodium vivax y Plasmodium falciparum: etapas relegadas en el desarrollo de vacunas
Contreras-Ochoa,Carla; Ramsey,Janine M;
Salud Pública de México , 2004, DOI: 10.1590/S0036-36342004000100009
Abstract: plasmodium gametocytes are responsible for transmission from the vertebrate host to the mosquito. plasmodium gametocytes undergo a complex cycle from asexual stages, through a poorly understood process characterized by expression of stage-specific proteins and adhesion molecules. gametocytes are capable of inducing specific humoral igg, and cellular responses, which include induction of tnfa, ifng and gd+ lymphocyte proliferation, in addition to immune responses to other stages of the parasite (sporozoite, exo-erythrocytic stages, erythrocytic stages). although transmission-blocking vaccines against plasmodium do not currently include components against the gametocytes (rather they focus on gametes, zygotes or ookinetes, stages which occur in the mosquito), further understanding of the mechanisms underlying gametocytogenesis and immune responses against these stages may provide additional strategies for more effective transmission inhibition.
Barriers to Treatment Access for Chagas Disease in Mexico
Jennifer M. Manne ,Callae S. Snively,Janine M. Ramsey,Marco Ocampo Salgado,Till B?rnighausen,Michael R. Reich
PLOS Neglected Tropical Diseases , 2013, DOI: 10.1371/journal.pntd.0002488
Abstract: Background According to World Health Organization (WHO) prevalence estimates, 1.1 million people in Mexico are infected with Trypanosoma cruzi, the etiologic agent of Chagas disease (CD). However, limited information is available about access to antitrypanosomal treatment. This study assesses the extent of access in Mexico, analyzes the barriers to access, and suggests strategies to overcome them. Methods and Findings Semi-structured in-depth interviews were conducted with 18 key informants and policymakers at the national level in Mexico. Data on CD cases, relevant policy documents and interview data were analyzed using the Flagship Framework for Pharmaceutical Policy Reform policy interventions: regulation, financing, payment, organization, and persuasion. Data showed that 3,013 cases were registered nationally from 2007–2011, representing 0.41% of total expected cases based on Mexico's national prevalence estimate. In four of five years, new registered cases were below national targets by 11–36%. Of 1,329 cases registered nationally in 2010–2011, 834 received treatment, 120 were pending treatment as of January 2012, and the treatment status of 375 was unknown. The analysis revealed that the national program mainly coordinated donation of nifurtimox and that important obstacles to access include the exclusion of antitrypanosomal medicines from the national formulary (regulation), historical exclusion of CD from the social insurance package (organization), absence of national clinical guidelines (organization), and limited provider awareness (persuasion). Conclusions Efforts to treat CD in Mexico indicate an increased commitment to addressing this disease. Access to treatment could be advanced by improving the importation process for antitrypanosomal medicines and adding them to the national formulary, increasing education for healthcare providers, and strengthening clinical guidelines. These recommendations have important implications for other countries in the region with similar problems in access to treatment for CD.
Contribuciones de la genética y la proteómica al estudio de la enfermedad de Chagas
López-Ordó?ez,Teresa; Panzera,Francisco; Tun-Ku,Ezequiel; Ferrandis,Inés; Ramsey,Janine M;
Salud Pública de México , 2009, DOI: 10.1590/S0036-36342009000900007
Abstract: chagas disease represents one of the more significant public health problems in the americas. information regarding the genome and proteome of vectors and parasite, as well as their interactions, will be essential to develop specific and effective diagnostic and preventive tools. advances that have contributed to the design, implementation, and efficacy of disease surveillance and control activities are reviewed. genomic and proteomic information has contributed to a better understanding of vector distributions and dispersion, diversity, population dynamics, and control targets (populations and species). in addition, genomic and proteomic studies have impacted parasite diagnostics, trypanosoma cruzi population dynamics, pharmacological treatment and knowledge of parasite-host interactions. discussion of these contributions includes expectations for future basic and applied research questions.
A Regulatory Structure for Working with Genetically Modified Mosquitoes: Lessons from Mexico
Janine M. Ramsey,J. Guillermo Bond,Maria Elena Macotela,Luca Facchinelli,Laura Valerio,David M. Brown,Thomas W. Scott,Anthony A. James
PLOS Neglected Tropical Diseases , 2014, DOI: 10.1371/journal.pntd.0002623
Abstract:
Ecological Connectivity of Trypanosoma cruzi Reservoirs and Triatoma pallidipennis Hosts in an Anthropogenic Landscape with Endemic Chagas Disease
Janine M. Ramsey, Ana E. Gutiérrez-Cabrera, Liliana Salgado-Ramírez, A. Townsend Peterson, Victor Sánchez-Cordero, Carlos N. Ibarra-Cerde?a
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0046013
Abstract: Traditional methods for Chagas disease prevention are targeted at domestic vector reduction, as well as control of transfusion and maternal-fetal transmission. Population connectivity of Trypanosoma cruzi-infected vectors and hosts, among sylvatic, ecotone and domestic habitats could jeopardize targeted efforts to reduce human exposure. This connectivity was evaluated in a Mexican community with reports of high vector infestation, human infection, and Chagas disease, surrounded by agricultural and natural areas. We surveyed bats, rodents, and triatomines in dry and rainy seasons in three adjacent habitats (domestic, ecotone, sylvatic), and measured T. cruzi prevalence, and host feeding sources of triatomines. Of 12 bat and 7 rodent species, no bat tested positive for T. cruzi, but all rodent species tested positive in at least one season or habitat. Highest T. cruzi infection prevalence was found in the rodents, Baiomys musculus and Neotoma mexicana. In general, parasite prevalence was not related to habitat or season, although the sylvatic habitat had higher infection prevalence than by chance, during the dry season. Wild and domestic mammals were identified as bloodmeals of T. pallidipennis, with 9% of individuals having mixed human (4.8% single human) and other mammal species in bloodmeals, especially in the dry season; these vectors tested >50% positive for T. cruzi. Overall, ecological connectivity is broad across this matrix, based on high rodent community similarity, vector and T. cruzi presence. Cost-effective T. cruzi, vector control strategies and Chagas disease transmission prevention will need to consider continuous potential for parasite movement over the entire landscape. This study provides clear evidence that these strategies will need to include reservoir/host species in at least ecotones, in addition to domestic habitats.
Field Cage Studies and Progressive Evaluation of Genetically-Engineered Mosquitoes
Luca Facchinelli ,Laura Valerio,Janine M. Ramsey,Fred Gould,Rachael K. Walsh,Guillermo Bond,Michael A. Robert,Alun L. Lloyd,Anthony A. James,Luke Alphey,Thomas W. Scott
PLOS Neglected Tropical Diseases , 2013, DOI: 10.1371/journal.pntd.0002001
Abstract: Background A genetically-engineered strain of the dengue mosquito vector Aedes aegypti, designated OX3604C, was evaluated in large outdoor cage trials for its potential to improve dengue prevention efforts by inducing population suppression. OX3604C is engineered with a repressible genetic construct that causes a female-specific flightless phenotype. Wild-type females that mate with homozygous OX3604C males will not produce reproductive female offspring. Weekly introductions of OX3604C males eliminated all three targeted Ae. aegypti populations after 10–20 weeks in a previous laboratory cage experiment. As part of the phased, progressive evaluation of this technology, we carried out an assessment in large outdoor field enclosures in dengue endemic southern Mexico. Methodology/Principal Findings OX3604C males were introduced weekly into field cages containing stable target populations, initially at 10:1 ratios. Statistically significant target population decreases were detected in 4 of 5 treatment cages after 17 weeks, but none of the treatment populations were eliminated. Mating competitiveness experiments, carried out to explore the discrepancy between lab and field cage results revealed a maximum mating disadvantage of up 59.1% for OX3604C males, which accounted for a significant part of the 97% fitness cost predicted by a mathematical model to be necessary to produce the field cage results. Conclusions/Significance Our results indicate that OX3604C may not be effective in large-scale releases. A strain with the same transgene that is not encumbered by a large mating disadvantage, however, could have improved prospects for dengue prevention. Insights from large outdoor cage experiments may provide an important part of the progressive, stepwise evaluation of genetically-engineered mosquitoes.
Current and Future Niche of North and Central American Sand Flies (Diptera: Psychodidae) in Climate Change Scenarios
David Moo-Llanes,Carlos N. Ibarra-Cerde?a,Eduardo A. Rebollar-Téllez,Sergio Ibá?ez-Bernal,Camila González,Janine M. Ramsey
PLOS Neglected Tropical Diseases , 2013, DOI: 10.1371/journal.pntd.0002421
Abstract: Ecological niche models are useful tools to infer potential spatial and temporal distributions in vector species and to measure epidemiological risk for infectious diseases such as the Leishmaniases. The ecological niche of 28 North and Central American sand fly species, including those with epidemiological relevance, can be used to analyze the vector's ecology and its association with transmission risk, and plan integrated regional vector surveillance and control programs. In this study, we model the environmental requirements of the principal North and Central American phlebotomine species and analyze three niche characteristics over future climate change scenarios: i) potential change in niche breadth, ii) direction and magnitude of niche centroid shifts, iii) shifts in elevation range. Niche identity between confirmed or incriminated Leishmania vector sand flies in Mexico, and human cases were analyzed. Niche models were constructed using sand fly occurrence datapoints from Canada, USA, Mexico, Guatemala and Belize. Nine non-correlated bioclimatic and four topographic data layers were used as niche components using GARP in OpenModeller. Both B2 and A2 climate change scenarios were used with two general circulation models for each scenario (CSIRO and HadCM3), for 2020, 2050 and 2080. There was an increase in niche breadth to 2080 in both scenarios for all species with the exception of Lutzomyia vexator. The principal direction of niche centroid displacement was to the northwest (64%), while the elevation range decreased greatest for tropical, and least for broad-range species. Lutzomyia cruciata is the only epidemiologically important species with high niche identity with that of Leishmania spp. in Mexico. Continued landscape modification in future climate change will provide an increased opportunity for the geographic expansion of NCA sand flys' ENM and human exposure to vectors of Leishmaniases.
Opportunity Cost for Early Treatment of Chagas Disease in Mexico
Janine M. Ramsey,Miguel Elizondo-Cano,Gilberto Sanchez-González,Adriana Pe?a-Nieves,Alejandro Figueroa-Lara
PLOS Neglected Tropical Diseases , 2014, DOI: 10.1371/journal.pntd.0002776
Abstract: Background Given current neglect for Chagas disease in public health programs in Mexico, future healthcare and economic development policies will need a more robust model to analyze costs and impacts of timely clinical attention of infected populations. Methodology/Principal Findings A Markov decision model was constructed to simulate the natural history of a Chagas disease cohort in Mexico and to project the associated short and long-term clinical outcomes and corresponding costs. The lifetime cost for a timely diagnosed and treated Chagas disease patient is US$ 10,160, while the cost for an undiagnosed individual is US$ 11,877. The cost of a diagnosed and treated case increases 24-fold from early acute to indeterminate stage. The major cost component for lifetime cost was working days lost, between 44% and 75%, depending on the program scenario for timely diagnosis and treatment. Conclusions/Significance In the long term, it is cheaper to diagnose and treat chagasic patients early, instead of doing nothing. This finding by itself argues for the need to shift current policy, in order to prioritize and attend this neglected disease for the benefit of social and economic development, which implies including treatment drugs in the national formularies. Present results are even more relevant, if one considers that timely diagnosis and treatment can arrest clinical progression and enhance a chronic patient's quality of life.
Phylogeny and Niche Conservatism in North and Central American Triatomine Bugs (Hemiptera: Reduviidae: Triatominae), Vectors of Chagas' Disease
Carlos N. Ibarra-Cerde?a,Alejandro Zaldívar-Riverón,A. Townsend Peterson,Víctor Sánchez-Cordero,Janine M. Ramsey
PLOS Neglected Tropical Diseases , 2014, DOI: 10.1371/journal.pntd.0003266
Abstract: The niche conservatism hypothesis states that related species diverge in niche characteristics at lower rates than expected, given their lineage divergence. Here we analyze whether niche conservatism is a common pattern among vector species (Hemiptera: Reduviidae: Triatominae) of Trypanosoma cruzi that inhabit North and Central America, a highly heterogeneous landmass in terms of environmental gradients. Mitochondrial and nuclear loci were used in a multi-locus phylogenetic framework to reconstruct phylogenetic relationships among species and estimate time of divergence of selected clades to draw biogeographic inferences. Then, we estimated similarity between the ecological niche of sister species and tested the niche conservatism hypothesis using our best estimate of phylogeny. Triatoma is not monophyletic. A primary clade with all North and Central American (NCA) triatomine species from the genera Triatoma, Dipetalogaster, and Panstrongylus, was consistently recovered. Nearctic species within the NCA clade (T. p. protracta, T. r. rubida) diverged during the Pliocene, whereas the Neotropical species (T. phyllosoma, T. longipennis, T. dimidiata complex) are estimated to have diverged more recently, during the Pleistocene. The hypothesis of niche conservatism could not be rejected for any of six sister species pairs. Niche similarity between sister species best fits a retention model. While this framework is used here to infer niche evolution, it has a direct impact on spatial vector dynamics driven by human population movements, expansion of transportation networks and climate change scenarios.
Dengue in the Americas: challenges for prevention and control
Gómez-Dantés, Héctor;Willoquet, Janine Ramsey;
Cadernos de Saúde Pública , 2009, DOI: 10.1590/S0102-311X2009001300003
Abstract: dengue is the most important vector-borne disease in the americas and threatens the lifes of millions of people in developing countries. imprecise morbidity and mortality statistics underestimate the magnitude of dengue as a regional health problem. as a result, it is considered a low priority by the health sector with no timely steps for effective control. dengue is perceived as a problem of "others" (individually, collectively and institutionally), therefore responsibility for its control is passed on to others (neighbors, the community, municipality, health institutions, or other governmental agencies). with no precise risk indicators available there is little opportunity for timely diagnoses, treatment, health interventions or vector control (poor surveillance). solutions only targeting the vector reduce the impact of interventions and there is no sustainable control. without political commitment there are insufficient resources to face the problem. this paper discusses the challenges for prevention and control in the americas.
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