Sickle cell anaemia – a rare disease of increasing global importance

By Professor Thomas Williams, Chair in Haemoglobinopathy Research, Faculty of Medicine, Department of Medicine

SCDSickle Cell Disease (SCD) is the commonest serious genetic condition of humans. The disease is caused by an inherited defect in haemoglobin, the red pigment within red cells that is important for the carriage of oxygen in the blood, and results in a life-long illness characterised by recurrent pain, ill health and chronic anaemia.

Few NCDs could be more neglected than SCD. Over 300,000 children are born with the condition every year, most in resource limited settings in Africa and India, where between 50-90% continue to die, most undiagnosed, before they reach their fifth birthday. This is despite the fact that in resource rich countries, the majority of those born with SCD today can expect to lead a reasonable quality of life into late adulthood, largely on the basis of a handful of reasonably cheap and easily affordable interventions. Although there have been a number of recent promising recent developments, including the recognition of SCD by both the United Nations and the World Health Organization as a condition of major and growing importance, for the most part SCD remains virtually invisible on the global health agenda. In common with many neglected NCDs, to a large extent this can be attributed to three interrelated issues: the fact that its greatest burden falls on the world’s poorest communities, the lack of reliable data and inadequate political will.

SCD is most common in tropical regions of the world because carriers (who have sickle cell trait) are strongly protected from malaria – a fact that has led to a selective advantage through their increased survival. The global distribution of the disease itself is centred in the tropics. Approximately half of those affected are born in just three countries: Nigeria, the Democratic Republic of Congo and India, the vast majority of the remainder being born in West, Central and Eastern Africa. According to the latest estimates from the Global Burden of Disease Survey the disease resulted in more than 5 million disability adjusted life years lost and almost 3 million years lived with disability in 2010 alone.

These global figures for morbidity and mortality should be considered in the context of data from the North, where many countries have adopted universal screening and where most now provide comprehensive care for affected individuals. Providing such services is within the reach in many less affluent countries: successful pilot studies of newborn screening have been conducted in several African countries and, in comparison to diseases of higher priority (such as HIV, TB and malaria), the provision of basic care in specialist clinics is not expensive. If widely implemented, such approaches could save the lives of almost ten million children worldwide between now and 2050.

So how can SCD be brought out of the shadows from its current status as a virtually invisible neglected disease? Perhaps most importantly, we need better data, without which it will remain difficult to persuade ministries of health, policy makers, funders and the pharmaceutical industry to devote appropriate resources to the condition. We need much better data on the birth frequencies and survival of children with SCD at the local area level. The introduction of early-life screening for SCD in resource poor countries would be a huge advance, and could be made considerably simpler with the recent development of rapid tests that could circumvent the lack of quality-assured diagnostic laboratories and the logistics of returning results to patients.  Better data will lead to better advocacy for SCD at every level: from education in schools and colleges, through to groups of affected patients, the media, celebrities, politicians, funders and health agencies internationally.

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