Browsing by Author "Low, Marcus"

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    A complex, high-performance agent-based model used to explore tuberculosis and COVID-19 case-finding interventions
    (2024) Low, Marcus; Kuttel, Michelle
    Tuberculosis (TB) claimed an estimated 1.5 million lives in 2021 and the COVID-19 pandemic resulted in 14.9 million excess deaths in 2020 and 2021 combined. With both these infectious diseases substantial pathogen transmission takes place before people report to health facilities. Diagnosing more people more quickly and placing them on treatment and/or isolating them is thus critical to achieving epidemiological control. Early diagnosis interventions include contact tracing and isolation, testing of asymptomatic people thought to be at high risk of infection, and in the case of TB, screening using chest X-rays. The impact of several such early diagnosis interventions on case detection have been studied in clinical trials, but the longer-term impact of these interventions on infections (incidence) and deaths (mortality) is not known. There are also unanswered questions as to the impact hypothetical future TB tests, for example allowing for more frequent testing, may have on TB incidence and mortality. We developed an agent-based model (ABM) called ABM Spaces and used it to ask: (i) What is the impact of four different TB case-finding interventions on TB detection rates, incidence and mortality? (ii) What is the impact of test frequency and test sensitivity on tuberculosis incidence? And (iii) What is the impact of contact tracing and isolation and variable test turnaround times on COVID-19 diagnosis and mortality? Such agent-based modelling, in which disease transmission and progression is modelled at the level of discrete individuals, has increasingly been used in recent decades to model infectious disease interventions. Relatively few ABMs in the literature contain substantial social structure (for example associating agents with specific households, workplaces, and school classes). We illustrate that such ABMs with substantial social structure can be developed in a way that is epidemiologically sound and show that this type of ABM is well-suited to the modelling of social interventions such as contact tracing. In the ABM Spaces model we found that testing of people at considerable risk of TB has a greater impact on TB incidence and mortality than mass X-ray screening, that the impact of the two interventions is additive, and that the impact of annual testing of high TB risk individuals is highly sensitive to HIV prevalence. We found that the relationship between test frequency and TB mortality and incidence is non-linear, with an inflection point at around the four-month mark. The COVID-19 version of ABM Spaces confirmed the potential of contact tracing and isolation to reduce incidence and mortality, but the effect was highly sensitive to test turnaround times.
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    Asylum story
    (2009) Low, Marcus
    asylum story is a short literary novel set in South Africa in the year 2019. The protagonist is infected with a deadly new respiratory disease and being held in a quarantine facility near a fictional town in the Karoo. The novel spans a six-month period during which the protagonist becomes involved in an ultimately failed attempt to escape. The novel is partly inspired by the Department of Health's decision in 2007 to place patients with drug-resistant strains of tuberculosis into quarantine. Many patients died in this enforced captivity. Conditions in some facilities were reportedly very poor and in 2008 there was a high-profile escape from the Jose Pearson quarantine facility. Though the disease in the novel is not drug-resistant tuberculosis, it is something similar, and the response to the fictional disease is comparable in some ways to the real-life medical response to the TB scare. The novel is set in a universe that is similar but different to our own, allowing the exploration of universal themes without the constraint of a rigid representation of current reality.
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    Transnational mobilisation on access to medicines: The global movement around the imatinib mesylate case and its roots in the AIDS movement
    (2014) Grebe, Eduard; Low, Marcus
    Starting in 2006, a patent dispute emerged in India with significant implications for global access to medicine. An application by Novartis for a 'new formulation' patent on the beta crystalline form of the cancer drug imatinib mesylate was rejected. Novartis responded by challenging the legality of provisions designed to protect access to medicines in India's patent legislation. A global activist movement emerged in defence of these aspects of Indian patent legislation mainly because the challenge threatened access to medicine at a systemic level, given India's critical role as a supplier of generic medicines to developing countries. The mobilisation described in this paper exploited existing activist networks and broader 'networks of influence' built during prior campaigns conducted around access to antiretroviral drugs. AIDS activists consequently played a key role in the global mobilisation around the imatinib mesylate dispute, aimed at generating public outrage and political pressure against Novartis's challenge to Indian patent law. A critical 'broker' in these transnational networks is identified as the medical charity M�dicins sans Fronti�res (MSF), and specifically its dedicated medicines access campaign, which linked disparate activist groups together, disseminated information and mobilised AIDS activists across the world in support of the Indian patent flexibilities. In 2013 the Indian Supreme Court upheld the relevant sections of the law, representing a significant victory for the international medicines access movement. This movement illustrates the power of transnational mobilisation to help bring about 'moral consensus' and to deploy influence and social power at the global level sufficient to overcome substantial corporate power. But we also argue that both the emergence of the 'global AIDS movement' and the emergence of a transnational social movement around the imatinib mesylate dispute depended on a set of historical circumstances that are unlikely to persist and that the broader medicines access movement therefore faces significant challenges to its sustainability and future success.