Expanding and contracting
Authors: Zoë Mullan
Journal: The Lancet Global Health (2014)

This month's issue features a dichotomy between the globally spreading and the globally disappearing. Migration and ageing lie behind the spreading disorders featured; vaccination and other prevention methods behind the decline of the others.Frédéric Piel and colleagues' fascinating Article explores the effects of international migration since 1960 on the spread of the recessive gene (HbS) that causes sickle-cell anaemia. Before the transatlantic slave trade saw millions of African people forcibly relocated to the Americas, the textbook epidemiology of the HbS gene spoke of a disorder limited to malarious regions by virtue of the protective effect of HbS carrier status against malaria. Large-scale voluntary migration during the second half of the 20th century has seen a third shift—and one to which public health professionals everywhere must face up. Piel and colleagues coupled data from the World Bank Global Bilateral Migration Database with their previously published estimates of national HbS frequencies to show that, between 1960 and 2000, the number of migrants with the HbS gene increased more rapidly than did the overall number of migrants, and the mean number of countries from which such individuals migrated to any one destination increased by 40%. Strikingly, the countries with the highest positive index of change (ie, the highest increase in HbS migration compared with overall migration) were Ecuador, Botswana, Portugal, and Thailand—ie, countries on four different continents.The findings add to the establishment of sickle-cell disease as “a major global public health problem”, according to Graham Serjeant in his accompanying Comment. Some countries with existing screening, education, and management programmes will need to scale up their efforts, and others with no services will need to implement them. Although no longer usually a fatal neonatal condition, sickle-cell disease still has profound consequences for patients in terms of quality of life, productivity, and health-care expense, and more global recognition of the disorder from governments, health-care professionals, and the general public would improve patients' life chances in all respects.Global recognition and concerted global action have brought the geographical extent of other diseases down to a few limited foci. Polio is the prime example, with just three countries—Afghanistan, Pakistan, and Nigeria—being endemic for the disease. India celebrated its third year of being polio-free on Jan 13. But eliminating the disease from these remaining outposts has been scuppered in recent years by what Richard Horton recently referred to as social chaos: “the disruption, disorder, disorganisation, and decay of civil society and its institutions”. Social chaos has disrupted vaccination programmes in all three polio-endemic countries and threatens to return others—eg, Syria—to the bad old days. In the second Article in this month's issue, Tara Mangal and colleagues attempt to drill down into the specifics of what perpetuates polio transmission in Nigeria—the country that accounted for more than 50% of cases worldwide in 2012. The findings reveal a complex mix of factors: poor vaccine efficacy in the north of the country; low vaccine coverage and population immunity in high-risk areas; and continued refusals and lack of awareness of the availability and importance of vaccination. In their accompanying Comment, Festus Adu and Itam Hogan Itam point to other potential influences such as political infighting, cultural perceptions of having a disabled child, and maternal education. The situation in Nigeria has improved somewhat since 2012 after new strategies were put in place to address some of these factors, and hopes are high that Nigeria can recover from the hiccup of 2011/12 and move towards elimination.Eradication of another infectious scourge—malaria—is a goal not universally agreed upon. In our maiden issue last year, Jenny Liu and colleagues asked “Is it possible it? Is is worth it? Should we do it?” Ubydul Haque and colleagues' Article in this issue addresses the “Is it worth it?” component from the point of view of donor funds to Bangladesh. Bangladesh is on the path towards national elimination, and malaria is now endemic in only 13 of 64 districts. Haque and colleagues' findings suggest that Bangladesh's national malaria elimination programme is efficient and cost-effective and could provide an example to other countries embarking on elimination.There is a lot to learn from the research in this issue: by examining the successes and failures of different national programmes, the inevitable spread of genetic diseases can be managed and the gradual cornering of some of the world's major infectious diseases can be accelerated. This month's issue features a dichotomy between the globally spreading and the globally disappearing. Migration and ageing lie behind the spreading disorders featured; vaccination and other prevention methods behind the decline of the others. Frédéric Piel and colleagues' fascinating Article explores the effects of international migration since 1960 on the spread of the recessive gene (HbS) that causes sickle-cell anaemia. Before the transatlantic slave trade saw millions of African people forcibly relocated to the Americas, the textbook epidemiology of the HbS gene spoke of a disorder limited to malarious regions by virtue of the protective effect of HbS carrier status against malaria. Large-scale voluntary migration during the second half of the 20th century has seen a third shift—and one to which public health professionals everywhere must face up. Piel and colleagues coupled data from the World Bank Global Bilateral Migration Database with their previously published estimates of national HbS frequencies to show that, between 1960 and 2000, the number of migrants with the HbS gene increased more rapidly than did the overall number of migrants, and the mean number of countries from which such individuals migrated to any one destination increased by 40%. Strikingly, the countries with the highest positive index of change (ie, the highest increase in HbS migration compared with overall migration) were Ecuador, Botswana, Portugal, and Thailand—ie, countries on four different continents. The findings add to the establishment of sickle-cell disease as “a major global public health problem”, according to Graham Serjeant in his accompanying Comment. Some countries with existing screening, education, and management programmes will need to scale up their efforts, and others with no services will need to implement them. Although no longer usually a fatal neonatal condition, sickle-cell disease still has profound consequences for patients in terms of quality of life, productivity, and health-care expense, and more global recognition of the disorder from governments, health-care professionals, and the general public would improve patients' life chances in all respects. Global recognition and concerted global action have brought the geographical extent of other diseases down to a few limited foci. Polio is the prime example, with just three countries—Afghanistan, Pakistan, and Nigeria—being endemic for the disease. India celebrated its third year of being polio-free on Jan 13. But eliminating the disease from these remaining outposts has been scuppered in recent years by what Richard Horton recently referred to as social chaos: “the disruption, disorder, disorganisation, and decay of civil society and its institutions”. Social chaos has disrupted vaccination programmes in all three polio-endemic countries and threatens to return others—eg, Syria—to the bad old days. In the second Article in this month's issue, Tara Mangal and colleagues attempt to drill down into the specifics of what perpetuates polio transmission in Nigeria—the country that accounted for more than 50% of cases worldwide in 2012. The findings reveal a complex mix of factors: poor vaccine efficacy in the north of the country; low vaccine coverage and population immunity in high-risk areas; and continued refusals and lack of awareness of the availability and importance of vaccination. In their accompanying Comment, Festus Adu and Itam Hogan Itam point to other potential influences such as political infighting, cultural perceptions of having a disabled child, and maternal education. The situation in Nigeria has improved somewhat since 2012 after new strategies were put in place to address some of these factors, and hopes are high that Nigeria can recover from the hiccup of 2011/12 and move towards elimination. Eradication of another infectious scourge—malaria—is a goal not universally agreed upon. In our maiden issue last year, Jenny Liu and colleagues asked “Is it possible it? Is is worth it? Should we do it?” Ubydul Haque and colleagues' Article in this issue addresses the “Is it worth it?” component from the point of view of donor funds to Bangladesh. Bangladesh is on the path towards national elimination, and malaria is now endemic in only 13 of 64 districts. Haque and colleagues' findings suggest that Bangladesh's national malaria elimination programme is efficient and cost-effective and could provide an example to other countries embarking on elimination. There is a lot to learn from the research in this issue: by examining the successes and failures of different national programmes, the inevitable spread of genetic diseases can be managed and the gradual cornering of some of the world's major infectious diseases can be accelerated.