Ebola in west Africa: from disease outbreak to humanitarian crisis.

1034 www.thelancet.com/infection Vol 14 November 2014 The epidemic of Ebola haemorrhagic fever in west Africa is the 25th known outbreak since 1976, but is fundamentally diff erent from all previous cases. Besides the fact that it is the fi rst Ebola outbreak in west Africa, it is the largest and longest Ebola epidemic, and the fi rst to involve three entire countries and capital cities, with around 5000 cases and 2500 deaths so far. How could it get to this point? The answer is the synergy of several factors that created a perfect storm: a context of decades of civil war leading to a low level of trust in authorities, even when these are working hard to reconstruct the country; dysfunctional health services with a major scarcity of health workers, especially in Liberia and Sierra Leone (another consequence of armed confl ict); strong traditional beliefs in disease causation and even denial of the virus’ existence; high-risk traditional funeral practices that amplify transmission, in addition to more recent healing practices in some churches where the bodies of patients with Ebola are touched; a slow and inadequate national and international response (although this is now changing); and high population mobility across borders—something that has not happened around previous outbreaks in central Africa. With whole countries aff ected, and an unprecedented number of infected and exposed people, the epidemic will be far more diffi cult to control than all previous outbreaks, which typically occurred around hospitals in rural areas or small towns. The sheer scale of the outbreak has, in itself, fundamentally changed the epidemiology, making the disease control prospects bleak. Overwhelmed treatment and isolation facilities turn patients away, so they remain in the community for longer, resulting in even more cases. So the main diff erence between this and previous epidemics is merely scale, not a mutated Ebola virus. With a doubling time of around 2 weeks in Monrovia, Liberia, the window of opportunity for control becomes ever narrower. The risk is also very real that other neighbouring countries, such as Côte d’Ivoire, will soon be aff ected, although Senegal seems to have eff ectively averted an outbreak following the introduction of Ebola infection to the country by a Guinean man. The west African epidemic has profoundly changed how we view Ebola virus infection, which has transformed from a rare event in central Africa into a major public health and destabilising humanitarian crisis. This situation was totally unexpected, but perhaps it should not have been. A recent analysis of the fi rst epidemic in 1976 in Yambuku (Democratic Republic of the Congo) suggests that even here, reproduction number, R0, in the community (not just the hospital) was probably greater than one. This fi nding implies that a large-scale community outbreak was always possible given suffi cient time. The recent epidemic has confi rmed that R0 for Ebola in African communities seems to be substantially higher than one, which implies that even if we curtail this outbreak, we should expect another major one to occur eventually. This shift in thinking has major implications for what is needed to stop the epidemic. Caring for patients, isolating infectious individuals, protecting health staff and other caregivers, safe burials, and contact tracing are the keystones of epidemic control. However, in the face of a massive epidemic with tens of thousands of contacts, implementation challenges of operating 4 Lönnroth K, Castro K, Chakaya JM, et al. Tuberculosis control and elimination 2010–50: cure, care, and social development. Lancet 2010; 375: 1814–29. 5 Tanimura T, Jaramillo E, Weil D, Raviglione M, Lönnroth K. Financial burden for tuberculosis patients in lowand middle-income countries—a systematic review. Eur Respir J 2014; 43: 1763–75. 6 WHO. Global strategy and targets for tuberculosis prevention, care and control after 2015. A67/11. Geneva: World Health Organization, 2014. 7 Lönnroth K, Glaziou P, Weil D, Floyd K, Uplekar M, Raviglione M. Monitoring universal health coverage and social protection in the context of tuberculosis care and prevention. PLoS Med 11: e1001693. 8 Boccia D, Hargreaves J, Lönnroth K, et al. Cash transfer and microfi nance interventions for tuberculosis control: review of the impact evidence and policy implications. Int J Tuberc Lung Dis 2011; 15: S37–49. 9 Rose G. Sick individuals and sick populations. Int J Epidem 1985; 14: 32–38. 10 WHO. Towards tuberculosis elimination in low-incidence countries: a framework. Geneva: World Health Organization, 2014. 11 Lönnroth K, Migliori GB, Raviglione M. Towards tuberculosis elimination in low-incidence countries—refl ections from a global consultation. Ann Intern Med (in press).