Global Challenge Of Malaria, The: Past Lessons And Future Prospects

Past Lessons and Future Prospects

Frank M Snowden, Richard Bucala

• Publisher: WSPC
• Year: 2014
• eBook ISBN: 9789814405591
• Topic: Biological Sciences
• Subtopic: Science General
• Index: Biological Sciences

Malaria is one of the most important “emerging” or “resurgent” infectious diseases. According to the World Health Organization, this mosquito-borne infection is a leading cause of suffering, death, poverty, and underdevelopment in the world today. Every year 500 million people become severely ill from malaria and more than a million people die, the great majority of them women and children living in sub-Saharan Africa. In 2008, it was estimated, a child would die of the disease every thirty seconds, making malaria — together with HIV/AIDS and tuberculosis — a global public health emergency. This is in stark contrast to the heady visions of the 1950s predicting complete global eradication of the ancient scourge. What went wrong?

This question warrants a closer look at not just the disease itself, but its long history and the multitude of strategies to combat its spread. This book collects the many important milestones in malaria control and treatment in one convenient volume. Importantly, it also traces the history of the disease from the 1920s to the present, and over several continents. It is the first multidisciplinary volume of its kind combining historical and scientific information that addresses the global challenge of malaria control.

Malaria remains as resurgent as ever and The Global Challenge of Malaria: Past Lessons and Future Prospects will examine this challenge — and the range of strategies and tools to confront it — from an interdisciplinary and transnational perspective.

Contents:

• Lessons of History:
  • Malaria in America (Margaret Humphreys)
  • Technological Solutions: The Rockefeller Insecticidal Approach to Malaria Control, 1920–1950 (Darwin H Stapleton)
  • Malaria Control and Eradication Projects in Tropical Africa, 1945–1965 (James L A Webb, Jr)
  • The Use and Misuse of History: Lessons from Sardinia (Frank M Snowden)
  • Popular Education and Participation in Malaria Control: A Historical Overview (Socrates Litsios)
• Scientific, Medical, and Public Health Perspectives:
  • The Contribution of the Gambia to Malaria Research (Brian Greenwood)
  • Insecticide–Treated Bednets and Malaria Control: Strategies, Implementation, and Outcome (Harry V Flaster, Emily Mosites, and Brian G Blackburn)
  • The Scientific and Medical Challenge of Malaria (Tiffany Sun and Richard Bucala)

Readership: Historians of medicine; research scientists; clinicians, especially in the specialties of tropical medicine and infectious diseases; public health officials; environmentalists; and students in public health and history of medicine programs; general readers interested in contemporary issues of global health.

Part I

Lessons of History

1	Malaria in America
	Margaret Humphreys

Introduction

Malaria was once a major cause of illness and death in the United States, although it is now almost entirely limited to imported cases arriving from other countries where the disease persists.¹ By 1950, home-grown malaria had disappeared in the United States, as well as in other temperate countries such as England, Holland, Spain, and Italy. Their stories of eradication make tempting models for those seeking to control a disease that still sickens and kills millions of people in the world today, most of them living in tropical and sub-tropical environments. As major new initiatives in the twenty-first century once again take on the microscopic predator carried in the mosquito’s spittle, it is worth asking whether history can offer lessons that can guide the effort.

Ten years ago I concluded that historical research on malaria in the United States bore no “relevance for the beleaguered international malarial community,” as the story contained “no startling revelations about how to fight malaria,” and instead described methods and processes already well known to malaria campaigners.² In retrospect, I have come to conclude that this assessment was too modest. George Santayana, in a now famous comment concerning history, said “Those who cannot remember the past, are condemned to repeat it.”³ While the history of malaria in the United States offers no simple solutions for today’s malaria challenges, it does contain lessons that those designing modern malaria wars would do well to keep in mind. Although no one now thinks, as optimistic malariologists did in the 1950s, that the victory over malaria in the United States and Europe which had been won with DDT and chloroquine could be easily duplicated elsewhere, it is important to sort out the geographical, economic, social and political differences that contributed to malaria’s demise in the developed western countries in order to recognize how the possible interventions available then and now interact with these various factors.

This chapter will first briefly outline malaria’s history in the United States, focusing particularly on several points along the way when malaria escalated or declined, with the goal of identifying the key causes of such expansion and contraction. It will then conclude with the policy implications that are suggested by this story.

The Parasites and Their Vectors

Although the label malaria is commonly used as if it were a single disease, there are actually four malaria parasites in humans that cause four different diseases. Only three were common in the United States, and for simplicity’s sake can be divided into severe (falciparum) malaria and milder (vivax and malariae) malaria. Falciparum can be deadly, especially when newly introduced to a population. Philip Curtin found that white British troops garrisoned on the west coast of Africa had a mortality rate in one year of over 50%; while other diseases such as yellow fever contributed to this slaughter, falciparum was the major culprit.⁴ Vivax is milder, and probably kills less than 5% of its victims, even without the benefit of curative drugs. Malariae seems to have had a minor presence in the United States, and for general purposes can be considered as similar to vivax.⁵ The parasites destroy red blood cells, leading to anemia and weakness. The spleen grows increasingly palpable as it struggles to clean up the destroyed red blood cells of the infected host. Falciparum malaria is more deadly because its parasites multiply in such massive numbers that they clog the capillaries of kidney, brain and liver, leading to failure of those essential organs. The vivax and falciparum organisms tend to cycle in and out of the red cells every 48 hours, giving the disease its common name in the nineteenth century, intermittent fever. And when the fever spikes, it causes severe chills, shaking and fever, a miserable agitation that may be related to the other common name for malaria, ague.⁶

Both diseases are particularly harsh to children and pregnant women. The malaria parasites compromise the placental blood supply, leading to miscarriage and stillbirth, while the mother’s normal decrease in immune surveillance during pregnancy makes her particularly vulnerable to the disease. On the other hand, those people that grow up in an environment of endemic malaria acquire tolerance to the organisms over time. Populations that have lived for millennia with the malaria parasites (and since the higher primates all have their own malarias, it is likely that the relationship goes back to the dawn of humans in Africa) have developed various hereditary traits that all attempt to make the red blood cell less susceptible to the invading parasite. Hence the sickle cell trait, G6PD deficiency, hemoglobin C trait, and the various thallasemias all appear to protect children against falciparum malaria. Many Africans also lack the Duffy antigen on the wall of their red cells, a benign mutation that protects them entirely from illness by the vivax organism. While the humans that left Africa to migrate to other parts of Europe and Asia probably included malaria carriers, it is likely that the disease died out in the small scattered bands of migrants, only to be reintroduced by trade after population growth.⁷

The predominant “malaria mosquito” in the United States was Anopheles quad-rimaculatus (A. quad.), a mosquito distributed broadly from the east coast to the middle of the country, and from Florida into lower Canada. The mosquito identified as A. quad. by malariologists in the mid-twentieth century has now been recognized to be a species complex, a phrase used to designate a cluster of mosquito types that may be designated sub-species by some and separate species by others. For details on these discussions, see the modern literature on genomics and distribution.⁸ For our purposes, the simple name will do, and the mosquito’s characteristics that are relevant to malaria transmission can be briefly described. First, A. quad. is a “promiscuous” feeder — malariologists dissected A. quads. from various states in the American south and found that mosquitoes trapped in environments where farm animals and people were equally available showed no preference in their choice of blood meal.⁹ Erwin Ackerknecht has argued that malaria retreated from the upper Mississippi Valley in part because as the number of farm animals increased, the mosquitoes chose them for feeding over humans.¹⁰ This does not seem to have been the case in the south, and may explain in part the persistence of malaria in that region. Anopheles freeborni was the predominant vector of malaria on the west coast, especially in California.¹¹

The major malaria vectors in the United States breed in still water, preferring swamps, ponds, and side pools of moving streams for laying their eggs. Once hatched, the mosquitoes rarely fly more than a mile from their breeding site, so malaria cases clustered around such wetlands. Malaria larvae float on the surface of the water, where they are susceptible to consumption by small fish, poisoning by larvicides, or smothering by a layer of oil.

Immigrants to the New World and the Arrival of Malaria

The migrants who settled in the area which would become the United States came from four major areas. First, the Native Americans arrived in prehistoric times, and appear to have been malaria-free until European settlement. The second group came from the various countries of Europe and the Mediterranean, and many of them would have brought vivax parasites along, as this organism is particularly adept at traveling. It can lie dormant in the liver for months, and later cause relapses which start a new cycle of infection wherever the unlucky victim may have roamed in the interim. The third population came from the west coast of Africa, when slave traders imported not only unfortunate humans but the parasites of malaria and, later, yellow fever. Africans were vehicles mainly for falciparum, since they were largely immune to vivax. Where Africans were forcibly settled and the climate was sufficiently sub-tropical, falciparum malaria blossomed in the settlements of the New World colonies. It is possible that immigrants from Asia contributed to the malaria prevalence on the west coasts of North, Central and South America during the last millennia.¹²

Falciparum malaria exploded most evidently in colonial South Carolina, where slave workers harvested rice from flooded fields that were ideal for breeding the anopheles species that carry the parasite from one person to another. The impact on mortality, particularly among whites, was so evident that we can pinpoint it fairly precisely, to the early 1680s.¹³ From being a fairly healthy colony, South Carolina became deadly for white people. Not coincidentally, the slave trade from the Caribbean and Africa expanded dramatically in just the same time period.¹⁴ One historian who studied South Carolina parish records for the eighteenth century found that 86% of white babies born in some parishes died before the age of 20, an astounding outcome likely due in large measure to falciparum malaria. It was no accident that well into the nineteenth century South Carolina had more black people than white, and that planter rhetoric proclaimed that only black people were physically suited to plantation work.¹⁵ White southerners learned to take their families to the Appalachian highlands or northern retreats during the late summer months when the heat was so unpleasant and deadly malaria prevailed.

Fortunately for white settlers in the lands that were to become the United States, falciparum did not tolerate the temperatures much further north than Tennessee and North Carolina. Vivax, on the other hand, was quite adapted to temperate climes, and extended as far north as Ontario and New Hampshire, and as far west as Iowa, Minnesota and Nebraska. Malaria made life miserable on the American frontier, as so much travel was by river and the earliest settlements were near those transportation waterways. Frontier housing was porous, and mill ponds (created to grind the ubiquitous corn that fed the pioneers and their animals) formed ideal nurseries for anopheles larvae. Malaria wreaked havoc in the 18^th century Chesapeake, and in the Connecticut River Valley; by the mid-nineteenth century it had traveled into the Midwest, following settlers on the Ohio, the Mississippi and the Missouri Rivers. By the time of the Civil War, both vivax and falciparum malaria were well entrenched in the United States, although by then it had become rare in New England.

Conditions during the war vastly amplified malaria’s spread among Americans. Whereas pest mosquitoes and notions of ill health had kept some areas sparsely populated, soldiers had to camp and fight in places they would otherwise have avoided. The James River peninsula, the shores of the Potomac River, the swamps around Vicksburg, and the occupation of the southern low country all brought men, malaria parasites, and mosquitoes together in great numbers. And those men were living outdoors, with only the slight protection of a tent to ward off mosquitoes. At times troops were issued mosquito netting in particularly buggy locations, but for most Civil War soldiers, these were an absent luxury. Of the several million men who served as soldiers in the war, at least a third on both sides sickened with malaria and 1 to 3% of those ill died of the disease. It was a major cause of disability during the conflict, even when it was not fatal.¹⁶

Fighting Back

By the mid-nineteenth century, humans began to fight back against malaria with increasing success. In 1821 Parisian researchers Joseph Pelletier and Joseph Caventou isolated quinine from the bark of the cinchona tree, and by the 1840s quinine pills were widely available on the malarious American frontier.¹⁷ As that frontier became more prosperous, settlers built houses more impervious to the cold, and moved to higher ground where mosquito pests were less abusive. Drainage to ready land for agriculture decreased breeding sites. With the spread of railroads from the 1830s and 1840s, settlers lost their dependence on waterways for transport. Al...

Table of contents

• Cover
• Halftitle
• Title
• Copyright
• Contents
• Introduction
• Acknowledgements
• Contributors
• Part I Lessons of History
• Part II Scientific, Medical, and Public Health Perspectives