Publications
362 results found
Griffin JT, Ferguson NM, Ghani AC, 2012, Linking the incidence and age patterns of clinical malaria to parasite prevalence using a mathematical model, Malaria Journal, Vol: 11
Walker P, Cauchemez S, Hartemink N, et al., 2012, Outbreaks of H5N1 in poultry in Thailand: the relative role of poultry production types in sustaining transmission and the impact of active surveillance in control, JOURNAL OF THE ROYAL SOCIETY INTERFACE, Vol: 9, Pages: 1836-1845, ISSN: 1742-5689
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- Citations: 21
Fournie G, Guitian J, Desvaux S, et al., 2012, Identifying Live Bird Markets with the Potential to Act as Reservoirs of Avian Influenza A (H5N1) Virus: A Survey in Northern Viet Nam and Cambodia, PLOS ONE, Vol: 7, ISSN: 1932-6203
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- Citations: 54
Cairns M, Roca-Feltrer A, Garske T, et al., 2012, Estimating the potential public health impact of seasonal malaria chemoprevention in African children, NATURE COMMUNICATIONS, Vol: 3, ISSN: 2041-1723
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- Citations: 115
Truscott J, Fraser C, Cauchemez S, et al., 2012, Essential epidemiological mechanisms underpinning the transmission dynamics of seasonal influenza, Journal of the Royal Society Interface, Vol: 9, Pages: 304-312, ISSN: 1742-5662
Seasonal influenza has considerable impact around the world, both economically and in mortality among risk groups, but there is considerable uncertainty as to the essential mechanisms and their parametrization. In this paper, we identify a number of characteristic features of influenza incidence time series in temperate regions, including ranges of annual attack rates and outbreak durations. By constraining the output of simple models to match these characteristic features, we investigate the role played by population heterogeneity, multiple strains, cross-immunity and the rate of strain evolution in the generation of incidence time series. Results indicate that an age-structured model with non-random mixing and co-circulating strains are both required to match observed time-series data. Our work gives estimates of the seasonal peak basic reproduction number, R0, in the range 1.6–3. Estimates of R0 are strongly correlated with the timescale for waning of immunity to current circulating seasonal influenza strain, which we estimate is between 3 and 8 years. Seasonal variation in transmissibility is largely confined to 15–30% of its mean value. While population heterogeneity and cross-immunity are required mechanisms, the degree of heterogeneity and cross-immunity is not tightly constrained. We discuss our findings in the context of other work fitting to seasonal influenza data.
Bousema R, 2012, Hitting Hotspots: Spatial Targeting of Malaria for Control and Elimination, PLoS Med, Vol: 9, Pages: e1001165-e1001165
<p>Teun Bousema and colleagues argue that targeting malaria “hotspots” is a highly efficient way to reduce malaria transmission at all levels of transmission intensity.</p>
Powers KA, Ghani AC, Miller WC, et al., 2011, Role of acute infection in HIV transmission Reply, LANCET, Vol: 378, Pages: 1914-1915, ISSN: 0140-6736
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- Citations: 2
White MT, Conteh L, Cibulskis R, et al., 2011, Costs and cost-effectiveness of malaria control interventions - a systematic review, MALARIA JOURNAL, Vol: 10
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- Citations: 185
Fournie G, Guitian FJ, Mangtani P, et al., 2011, Impact of the implementation of rest days in live bird markets on the dynamics of H5N1 highly pathogenic avian influenza, JOURNAL OF THE ROYAL SOCIETY INTERFACE, Vol: 8, Pages: 1079-1089, ISSN: 1742-5689
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- Citations: 49
White MT, Griffin JT, Churcher TS, et al., 2011, Modelling the impact of vector control interventions on Anopheles gambiae population dynamics, Parasites & Vectors, Vol: 4, ISSN: 1756-3305
BACKGROUND:Intensive anti-malaria campaigns targeting the Anopheles population have demonstrated substantial reductions in adult mosquito density. Understanding the population dynamics of Anopheles mosquitoes throughout their whole lifecycle is important to assess the likely impact of vector control interventions alone and in combination as well as to aid the design of novel interventions.METHODS:An ecological model of Anopheles gambiae sensu lato populations incorporating a rainfall-dependent carrying capacity and density-dependent regulation of mosquito larvae in breeding sites is developed. The model is fitted to adult mosquito catch and rainfall data from 8 villages in the Garki District of Nigeria (the 'Garki Project') using Bayesian Markov Chain Monte Carlo methods and prior estimates of parameters derived from the literature. The model is used to compare the impact of vector control interventions directed against adult mosquito stages--long-lasting insecticide treated nets (LLIN), indoor residual spraying (IRS)-- and directed against aquatic mosquito stages, alone and in combination on adult mosquito density.RESULTS:A model in which density-dependent regulation occurs in the larval stages via a linear association between larval density and larval death rates provided a good fit to seasonal adult mosquito catches. The effective mosquito reproduction number in the presence of density-dependent regulation is dependent on seasonal rainfall patterns and peaks at the start of the rainy season. In addition to killing adult mosquitoes during the extrinsic incubation period, LLINs and IRS also result in less eggs being oviposited in breeding sites leading to further reductions in adult mosquito density. Combining interventions such as the application of larvicidal or pupacidal agents that target the aquatic stages of the mosquito lifecycle with LLINs or IRS can lead to substantial reductions in adult mosquito density.CONCLUSIONS:Density-dependent regulation of anophel
Powers KA, Ghani AC, Miller WC, et al., 2011, The role of acute and early HIV infection in the spread of HIV and implications for transmission prevention strategies in Lilongwe, Malawi: a modelling study, LANCET, Vol: 378, Pages: 256-268, ISSN: 0140-6736
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- Citations: 256
Powers KA, Hoffman IF, Ghani AC, et al., 2011, Sexual Partnership Patterns in Malawi: Implications for HIV/STI Transmission, SEXUALLY TRANSMITTED DISEASES, Vol: 38, Pages: 657-666, ISSN: 0148-5717
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- Citations: 19
Okell LC, Griffin JT, Kleinschmidt I, et al., 2011, The Potential Contribution of Mass Treatment to the Control of <i>Plasmodium falciparum</i> Malaria, PLOS ONE, Vol: 6, ISSN: 1932-6203
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- Citations: 103
White MT, Griffin JT, Riley EM, et al., 2011, Efficacy model for antibody-mediated pre-erythrocytic malaria vaccines, PROCEEDINGS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES, Vol: 278, Pages: 1298-1305, ISSN: 0962-8452
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- Citations: 12
Cairns M, Ghani A, Okell L, et al., 2011, Modelling the Protective Efficacy of Alternative Delivery Schedules for Intermittent Preventive Treatment of Malaria in Infants and Children, PLOS ONE, Vol: 6, ISSN: 1932-6203
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- Citations: 11
Griffin JT, Garske T, Ghani AC, et al., 2011, Joint estimation of the basic reproduction number and generation time parameters for infectious disease outbreaks, BIOSTATISTICS, Vol: 12, Pages: 303-312, ISSN: 1465-4644
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- Citations: 22
Alonso PL, Eubank S, Ghani A, et al., 2011, A Research Agenda for Malaria Eradication: Modeling, PLOS MEDICINE, Vol: 8, ISSN: 1549-1277
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- Citations: 22
Garske T, Ghani AC, 2010, Uncertainty in the Tail of the Variant Creutzfeldt-Jakob Disease Epidemic in the UK, PLOS ONE, Vol: 5, ISSN: 1932-6203
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- Citations: 43
Chen MI, Ghani AC, 2010, Republished paper: Populations and partnerships: insights from metapopulation and pair models into the epidemiology of gonorrhoea and other sexually transmitted infections, SEXUALLY TRANSMITTED INFECTIONS, Vol: 86, Pages: III63-III69, ISSN: 1368-4973
Chen MI, Ghani AC, 2010, Republished paper: Populations and partnerships: insights from metapopulation and pair models into the epidemiology of gonorrhoea and other sexually transmitted infections, SEXUALLY TRANSMITTED INFECTIONS, Vol: 86, Pages: 63-69, ISSN: 1368-4973
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- Citations: 2
Griffin JT, Hollingsworth D, Okell LC, et al., 2010, STRATEGIES TOWARDS <i>PLASMODIUM FALCIPARUM</i> MALARIA ELIMINATION IN AFRICA USING CURRENTLY AVAILABLE TOOLS, 59th Annual Meeting of the American-Society-of-Tropical-Medicine-and-Hygiene (ASTMH), Publisher: AMER SOC TROP MED & HYGIENE, Pages: 262-262, ISSN: 0002-9637
Okell LC, Griffin J, Kleinschmidt I, et al., 2010, REDUCTION OF MALARIA TRANSMISSION BY MASS TREATMENT: A COMPARISON OF OPERATIONAL STRATEGIES, 59th Annual Meeting of the American-Society-of-Tropical-Medicine-and-Hygiene (ASTMH), Publisher: AMER SOC TROP MED & HYGIENE, Pages: 221-221, ISSN: 0002-9637
Hollingsworth D, Ghani A, 2010, HUMAN MOVEMENT PATTERNS RELEVANT FOR MALARIA TRANSMISSION IN TANZANIA AND MALI, 59th Annual Meeting of the American-Society-of-Tropical-Medicine-and-Hygiene (ASTMH), Publisher: AMER SOC TROP MED & HYGIENE, Pages: 45-45, ISSN: 0002-9637
Chen MI, Ghani AC, 2010, Populations and partnerships: insights from metapopulation and pair models into the epidemiology of gonorrhoea and other sexually transmitted infections, SEXUALLY TRANSMITTED INFECTIONS, Vol: 86, Pages: 433-439, ISSN: 1368-4973
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- Citations: 11
Griffin JT, Cairns M, Ghani AC, et al., 2010, Protective Efficacy of Intermittent Preventive Treatment of Malaria in Infants (IPTi) Using Sulfadoxine-Pyrimethamine and Parasite Resistance, PLOS ONE, Vol: 5, ISSN: 1932-6203
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- Citations: 29
Griffin JT, Hollingsworth TD, Okell LC, et al., 2010, Reducing Plasmodium falciparum malaria transmission in Africa: a model-based evaluation of intervention strategies., PLoS Med, Vol: 7, Pages: 1-27, ISSN: 1549-1676
BACKGROUND: Over the past decade malaria intervention coverage has been scaled up across Africa. However, it remains unclear what overall reduction in transmission is achievable using currently available tools. METHODS AND FINDINGS: We developed an individual-based simulation model for Plasmodium falciparum transmission in an African context incorporating the three major vector species (Anopheles gambiae s.s., An. arabiensis, and An. funestus) with parameters obtained by fitting to parasite prevalence data from 34 transmission settings across Africa. We incorporated the effect of the switch to artemisinin-combination therapy (ACT) and increasing coverage of long-lasting insecticide treated nets (LLINs) from the year 2000 onwards. We then explored the impact on transmission of continued roll-out of LLINs, additional rounds of indoor residual spraying (IRS), mass screening and treatment (MSAT), and a future RTS,S/AS01 vaccine in six representative settings with varying transmission intensity (as summarized by the annual entomological inoculation rate, EIR: 1 setting with low, 3 with moderate, and 2 with high EIRs), vector-species combinations, and patterns of seasonality. In all settings we considered a realistic target of 80% coverage of interventions. In the low-transmission setting (EIR approximately 3 ibppy [infectious bites per person per year]), LLINs have the potential to reduce malaria transmission to low levels (<1% parasite prevalence in all age-groups) provided usage levels are high and sustained. In two of the moderate-transmission settings (EIR approximately 43 and 81 ibppy), additional rounds of IRS with DDT coupled with MSAT could drive parasite prevalence below a 1% threshold. However, in the third (EIR = 46) with An. arabiensis prevailing, these interventions are insufficient to reach this threshold. In both high-transmission settings (EIR approximately 586 and 675 ibppy), either unrealistically high coverage levels (>90%) or novel tools and/or
Bousema T, Okell L, Shekalaghe S, et al., 2010, Revisiting the circulation time of Plasmodium falciparum gametocytes: molecular detection methods to estimate the duration of gametocyte carriage and the effect of gametocytocidal drugs, Malaria Journal, Vol: 9, ISSN: 1475-2875
BACKGROUND: There is renewed acknowledgement that targeting gametocytes is essential for malaria control and elimination efforts. Simple mathematical models were fitted to data from clinical trials in order to determine the mean gametocyte circulation time and duration of gametocyte carriage in treated malaria patients. METHODS: Data were used from clinical trials from East Africa. The first trial compared non-artemisinin combination therapy (non-ACT: sulphadoxine-pyrimethamine (SP) plus amodiaquine) and artemisinin-based combination therapy (ACT: SP plus artesunate (AS) or artemether-lumefantrine). The second trial compared ACT (SP+AS) with ACT in combination with a single dose of primaquine (ACT-PQ: SP+AS+PQ). Mature gametocytes were quantified in peripheral blood samples by nucleic acid sequence based amplification. A simple deterministic compartmental model was fitted to gametocyte densities to estimate the circulation time per gametocyte; a similar model was fitted to gametocyte prevalences to estimate the duration of gametocyte carriage after efficacious treatment. RESULTS: The mean circulation time of gametocytes was 4.6-6.5 days. After non-ACT treatment, patients were estimated to carry gametocytes for an average of 55 days (95% CI 28.7 - 107.7). ACT reduced the duration of gametocyte carriage fourfold to 13.4 days (95% CI 10.2-17.5). Addition of PQ to ACT resulted in a further fourfold reduction of the duration of gametocyte carriage. CONCLUSIONS: These findings confirm previous estimates of the circulation time of gametocytes, but indicate a much longer duration of (low density) gametocyte carriage after apparently successful clearance of asexual parasites. ACT shortened the period of gametocyte carriage considerably, and had the most pronounced effect on mature gametocytes when combined with PQ.
Dodd PJ, Millington KA, Ghani AC, et al., 2010, Interpreting Tuberculin Skin Tests in a Population With a High Prevalence of HIV, Tuberculosis, and Nonspecific Tuberculin Sensitivity, AMERICAN JOURNAL OF EPIDEMIOLOGY, Vol: 171, Pages: 1037-1045, ISSN: 0002-9262
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- Citations: 7
White MT, Griffin JT, Drakeley CJ, et al., 2010, Heterogeneity in malaria exposure and vaccine response: implications for the interpretation of vaccine efficacy trials, MALARIA JOURNAL, Vol: 9
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- Citations: 44
, 2010, Correction: A Bayesian Approach to Quantifying the Effects of Mass Poultry Vaccination upon the Spatial and Temporal Dynamics of H5N1 in Northern Vietnam, PLoS computational biology, Vol: 6, ISSN: 1553-734X
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