Publications
220 results found
Lessler J, Edmunds WJ, Halloran ME, et al., 2015, Seven challenges for model-driven data collection in experimental and observational studies, EPIDEMICS, Vol: 10, Pages: 78-82, ISSN: 1755-4365
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- Citations: 24
Griffin JT, Hollingsworth TD, Reyburn H, et al., 2015, Gradual acquisition of immunity to severe malaria with increasing exposure, Proceedings of the Royal Society B: Biological Sciences, Vol: 282, ISSN: 0962-8452
Truscott J, Hollingsworth TD, Anderson R, 2014, Modeling the Interruption of the Transmission of Soil-Transmitted Helminths by Repeated Mass Chemotherapy of School-Age Children, PLOS NEGLECTED TROPICAL DISEASES, Vol: 8, ISSN: 1935-2735
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- Citations: 32
Hollingsworth TD, Pulliam JRC, Funk S, et al., 2014, Seven challenges for modelling indirect transmission: Vector-borne diseases, macroparasites and neglected tropical diseases, Epidemics, Vol: 10, Pages: 16-20, ISSN: 1878-0067
Many of the challenges which face modellers of directly transmitted pathogens also arise when modelling the epidemiology of pathogens with indirect transmission – whether through environmental stages, vectors, intermediate hosts or multiple hosts. In particular, understanding the roles of different hosts, how to measure contact and infection patterns, heterogeneities in contact rates, and the dynamics close to elimination are all relevant challenges, regardless of the mode of transmission. However, there remain a number of challenges that are specific and unique to modelling vector-borne diseases and macroparasites. Moreover, many of the neglected tropical diseases which are currently targeted for control and elimination are vector-borne, macroparasitic, or both, and so this article includes challenges which will assist in accelerating the control of these high-burden diseases. Here, we discuss the challenges of indirect measures of infection in humans, whether through vectors or transmission life stages and in estimating the contribution of different host groups to transmission. We also discuss the issues of “evolution-proof” interventions against vector-borne disease.
Metcalf CJE, Andreasen V, Bjornstad ON, et al., 2014, Seven challenges in modeling vaccine preventable diseases, Epidemics, Vol: 10, Pages: 11-15, ISSN: 1878-0067
Vaccination has been one of the most successful public health measures since the introduction of basic sanitation. Substantial mortality and morbidity reductions have been achieved via vaccination against many infections, and the list of diseases that are potentially controllable by vaccines is growing steadily. We introduce key challenges for modeling in shaping our understanding and guiding policy decisions related to vaccine preventable diseases.
Pinsent A, Read JM, Griffin JT, et al., 2014, Risk factors for UK Plasmodium falciparum cases, Malaria Journal, Vol: 13
Anderson R, Truscott J, Hollingsworth TD, 2014, The coverage and frequency of mass drug administration required to eliminate persistent transmission of soil-transmitted helminths, Philosophical Transactions of the Royal Society B: Biological Sciences, Vol: 369, ISSN: 1471-2970
A combination of methods, including mathematical model construction, demographic plus epidemiological data analysis and parameter estimation, are used to examine whether mass drug administration (MDA) alone can eliminate the transmission of soil-transmitted helminths (STHs). Numerical analyses suggest that in all but low transmission settings (as defined by the magnitude of the basic reproductive number, R0), the treatment of pre-school-aged children (pre-SAC) and school-aged children (SAC) is unlikely to drive transmission to a level where the parasites cannot persist. High levels of coverage (defined as the fraction of an age group effectively treated) are required in pre-SAC, SAC and adults, if MDA is to drive the parasite below the breakpoint under which transmission is eliminated. Long-term solutions to controlling helminth infections lie in concomitantly improving the quality of the water supply, sanitation and hygiene (WASH). MDA, however, is a very cost-effective tool in long-term control given that most drugs are donated free by the pharmaceutical industry for poor regions of the world. WASH interventions, by lowering the basic reproductive number, can facilitate the ability of MDA to interrupt transmission.
Truscott JE, Hollingsworth TD, Brooker SJ, et al., 2014, Can chemotherapy alone eliminate the transmission of soil transmitted helminths?, PARASITES & VECTORS, Vol: 7, ISSN: 1756-3305
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- Citations: 99
Fraser C, Lythgoe K, Leventhal GE, et al., 2014, Virulence and Pathogenesis of HIV-1 Infection: An Evolutionary Perspective, SCIENCE, Vol: 343, Pages: 1328-+, ISSN: 0036-8075
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- Citations: 162
Hollingsworth TD, Truscott JE, Anderson RM, 2013, Chapter 9 - Transmission Dynamics of Ascaris lumbricoides – Theory and Observation, Ascaris: the Neglected Parasite, Pages: 231-262, ISBN: 978-0-12-396978-1
Anderson RM, Truscott JE, Pullan R, et al., 2013, How Effective Is School-Based Deworming for the Community-Wide Control of Soil-Transmitted Helminths?, PLOS NTDS, Vol: 2
Baggaley RF, White RG, Hollingsworth TD, et al., 2013, Heterosexual HIV-1 Infectiousness and Antiretroviral Use: Systematic Review of Prospective Studies of Discordant Couples., Epidemiology, Vol: 1, Pages: 110-121
BACKGROUND: : Recent studies have estimated the reduction in HIV-1 infectiousness with antiretroviral therapy (ART), but high-quality studies such as randomized controlled trials, accompanied by rigorous adherence counseling, are likely to overestimate the effectiveness of treatment-as-prevention in real-life settings.METHODS: : We attempted to summarize the effect of ART on HIV transmission by undertaking a systematic review and meta-analysis of HIV-1 infectiousness per heterosexual partnership (incidence rate and cumulative incidence over study follow-up) estimated from prospective studies of discordant couples. We used random-effects Poisson regression models to obtain summary estimates. When possible, the analyses were further stratified by direction of transmission (man-to-woman or woman-to-man) and economic setting (high- or low-income countries). Potential causes of heterogeneity of estimates were explored through subgroup analyses.RESULTS: : Fifty publications were included. Nine allowed comparison between ART and non-ART users within studies (ART-stratified studies), in which summary incidence rates were 3.6/100 person-years (95% confidence interval = 2.0-6.5) and 0.2/100 person-years (0.07-0.7) for non-ART- and ART-using couples, respectively (P < 0.001), constituting a 91% (79-96%) reduction in per-partner HIV-1 incidence rate with ART use. The 41 studies that did not stratify by ART use provided estimates with high levels of heterogeneity (I statistic) and few reported levels of ART use, making interpretation difficult. Nevertheless, estimates tended to be lower with ART use. Infectiousness tended to be higher for low-income than high-income settings, but there was no clear pattern by direction of transmission (man-to-woman and woman-to-man).CONCLUSIONS: : ART substantially reduces HIV-1 infectiousness within discordant couples, based on observational studies, and could play a major part in HIV-1 prevention efforts. However, the non-zero risk from par
Hollingsworth D, 2012, Counting Cases: How does mathematics help us control infectious diseases?, Science in Parliament, Vol: 69, Pages: 24-25
Anderson RM, Hollingsworth TD, Truscott J, et al., 2012, Optimisation of mass chemotherapy to control soil-transmitted helminth infection (vol 379, pg 289, 2012), LANCET, Vol: 379, Pages: 1102-1102, ISSN: 0140-6736
Anderson R, Hollingsworth TD, Truscott J, et al., 2012, Optimisation of mass chemotherapy to control soil-transmitted helminth infection, LANCET, Vol: 379, Pages: 289-290, ISSN: 0140-6736
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- Citations: 40
Anderson RM, Hollingsworth TD, Truscott J, et al., 2012, Erratum: Optimisation of mass chemotherapy to control soil-transmitted helminth infection (Lancet (2012) 379 (289-90)), The Lancet, Vol: 379, ISSN: 0140-6736
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
Hollingsworth TD, Klinkenberg D, Heesterbeek H, et al., 2011, Mitigation Strategies for Pandemic Influenza A: Balancing Conflicting Policy Objectives, Plos Computational Biology, Vol: 7, ISSN: 1553-7358
Mitigation of a severe influenza pandemic can be achieved using a range of interventions to reduce transmission. Interventions can reduce the impact of an outbreak and buy time until vaccines are developed, but they may have high social and economic costs. The non-linear effect on the epidemic dynamics means that suitable strategies crucially depend on the precise aim of the intervention. National pandemic influenza plans rarely contain clear statements of policy objectives or prioritization of potentially conflicting aims, such as minimizing mortality (depending on the severity of a pandemic) or peak prevalence or limiting the socio-economic burden of contact-reducing interventions. We use epidemiological models of influenza A to investigate how contact-reducing interventions and availability of antiviral drugs or pre-pandemic vaccines contribute to achieving particular policy objectives. Our analyses show that the ideal strategy depends on the aim of an intervention and that the achievement of one policy objective may preclude success with others, e.g., constraining peak demand for public health resources may lengthen the duration of the epidemic and hence its economic and social impact. Constraining total case numbers can be achieved by a range of strategies, whereas strategies which additionally constrain peak demand for services require a more sophisticated intervention. If, for example, there are multiple objectives which must be achieved prior to the availability of a pandemic vaccine (i.e., a time-limited intervention), our analysis shows that interventions should be implemented several weeks into the epidemic, not at the very start. This observation is shown to be robust across a range of constraints and for uncertainty in estimates of both R0 and the timing of vaccine availability. These analyses highlight the need for more precise statements of policy objectives and their assumed consequences when planning and implementing strategies to mitigate the impac
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
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
Fraser C, Hollingsworth TD, 2010, Interpretation of correlations in setpoint viral load in transmitting couples, AIDS, Vol: 24, Pages: 2596-2597, ISSN: 0269-9370
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- Citations: 8
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
Bezemer D, de Wolf F, Boerlijst MC, et al., 2010, 27 years of the HIV epidemic amongst men having sex with men in the Netherlands: An in depth mathematical model-based analysis, Epidemics, Vol: 2, Pages: 66-79
BackgroundThere has been increasing concern about a resurgent epidemic of HIV-1 amongst men having sex with men in the Netherlands, which has parallels with similar epidemics now occurring in many other countries.MethodsA transmission model applicable to HIV-1 epidemics, including the use of antiretroviral therapy, is presented in a set of ordinary differential equations. The model is fitted by maximum likelihood to national HIV-1 and AIDS diagnosis data from 1980 to 2006, estimating parameters on average changes in unsafe sex and time to diagnosis. Robustness is studied with a detailed univariate sensitivity analysis, and a range of hypothetical scenarios are explored for the past and next decade.ResultsWith a reproduction number around the epidemic threshold one, the HIV-1 epidemic amongst men having sex with men in the Netherlands is still not under control. Scenario analysis showed that in the absence of antiretroviral therapy limiting infectiousness in treated patients, the epidemic could have been more than double its current size. Ninety percent of new HIV transmissions are estimated to take place before diagnosis of the index case. Decreasing time from infection to diagnosis, which was 2.5 years on average in 2006, can prevent many future infections.ConclusionsSexual risk behaviour amongst men having sex with men who are not aware of their infection is the most likely factor driving this epidemic.
Hollingsworth TD, Laeyendecker O, Shirreff G, et al., 2010, HIV-1 Transmitting Couples Have Similar Viral Load Set-Points in Rakai, Uganda, PLOS PATHOGENS, Vol: 6, ISSN: 1553-7366
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- Citations: 76
Shirreff G, Hollingsworth TD, Hanage WP, et al., 2010, Modelling the between-host evolution of set-point viral load in HIV infection, INTERNATIONAL JOURNAL OF INFECTIOUS DISEASES, Vol: 14, Pages: E79-E79, ISSN: 1201-9712
Hollingsworth D, Ferguson N, Griffin J, et al., 2009, ESTIMATING THE RATE OF ACQUIRING IMMUNITY TO SEVERE DISEASE DUE TO <i>PLASMODIUM FALCIPARUM</i> WITH AGE AND EXPOSURE, 58th Annual Meeting of the American-Society-of-Tropical-Medicine-and-Hygiene, Publisher: AMER SOC TROP MED & HYGIENE, Pages: 258-259, ISSN: 0002-9637
Hollingsworth TD, 2009, Controlling infectious disease outbreaks: Lessons from mathematical modelling., J Public Health Policy, Vol: 30, Pages: 328-341, ISSN: 0197-5897
Epidemiological analysis and mathematical models are now essential tools in understanding the dynamics of infectious diseases and in designing public health strategies to contain them. They have provided fundamental concepts, such as the basic and effective reproduction number, generation times, epidemic growth rates, and the role of pre-symptomatic infectiousness, which are crucial in characterising infectious diseases. These concepts are outlined and their relevance in designing control policies for outbreaks is discussed. They are illustrated using examples from the 2003 severe acute respiratory syndrome outbreak, which was brought under control within a year, and from pandemic influenza planning, where mathematical models have been used extensively.
Fraser C, Donnelly CA, Cauchemez S, et al., 2009, Influenza: Making Privileged Data Public Response, SCIENCE, Vol: 325, Pages: 1072-1073, ISSN: 0036-8075
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- Citations: 2
Anderson RM, Hollingsworth TD, Nokes DJ, 2009, Mathematical models of transmission and control, Oxford Textbook of Public Health, Editors: Detels, Beaglehole, Lansang, Gulliford, Oxford, UK, Publisher: Oxford University Press, ISBN: 9780199218707
Rhodes CJ, Hollingsworth TD, 2009, Variational data assimilation with epidemic models, JOURNAL OF THEORETICAL BIOLOGY, Vol: 258, Pages: 591-602, ISSN: 0022-5193
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- Citations: 31
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