The Coming Plague (12 page)
Authors: Laurie Garrett
In September, a WHO investigation reached a painful conclusion: although the Type C vaccine had been tried in only a couple of field settings and the Type A vaccine had to be considered completely experimental, nothing else could possibly stop the burgeoning epidemic.
Furthermore, WHO felt strongly that a vaccine combining immunization against Types A and C was essential, and warned that “the future of any vaccination programme will be in jeopardy” if the public loses faith in health efforts because people continue to die after receiving only the partial vaccination protection; the expected result of using only one vaccine.
The WHO decision was actually pro forma: the military government of Brazil had already decided in an August 5 meeting in Brasilia to vaccinate every citizen living in the epidemic area.
15
While panic mounted, France's Institut Mérieux agreed to manufacture the combination A/C vaccine for Brazil, and hurriedly built a new factory outside Lyons, France, for the purpose. Within four months, Mérieux would have attained the ability to manufacture and ship to Brazil 500,000 vaccine doses a week.
16
The vaccine was composed of the sugary piecesâthe polysaccharidesâof the bacteria that gave them their A and C immunological statuses.
17
15
While panic mounted, France's Institut Mérieux agreed to manufacture the combination A/C vaccine for Brazil, and hurriedly built a new factory outside Lyons, France, for the purpose. Within four months, Mérieux would have attained the ability to manufacture and ship to Brazil 500,000 vaccine doses a week.
16
The vaccine was composed of the sugary piecesâthe polysaccharidesâof the bacteria that gave them their A and C immunological statuses.
17
Between August 1974 and mid-January 1975 while waiting for the vaccine, however, McCormick and Brazilian officials had few tools at hand. Joe decided to focus on public education, and immediately taught himself Portuguese. By October he was giving lengthy interviews and holding press conferences, calling for calm and reason.
“I've got to be clear about what I say,” McCormick thought, “and give the people confidence.”
As an outsider, McCormick had a special role to playâand a delicate one. For ten years Brazil had been ruled by a military junta noted for its brutality. Countless students, labor leaders, religious activists, and representatives of the country's underclass had “disappeared” by late 1974. “Disappearance” was a euphemism for death, preceded usually by kidnapping and torture. Rumors and fear ruled public opinion, and few of the nation's poor trusted government pronouncements.
On the whole, however, the Brazilian Ministry of Health's meningococcal
announcements were accurate. It was part of McCormick's diplomatic mission to publicly support the government's statements about the epidemic while clearly maintaining a critical distance from the junta itself. Such dicey politics weren't taught at Duke University Medical School. Or at the CDC training program.
announcements were accurate. It was part of McCormick's diplomatic mission to publicly support the government's statements about the epidemic while clearly maintaining a critical distance from the junta itself. Such dicey politics weren't taught at Duke University Medical School. Or at the CDC training program.
McCormick had to wing it. Over the months he learned how to gently point out that nearly all meningitis sufferers came from communities of acute poverty, such as the massive favelas of São Paulo and Rio de Janeiro, without directly attacking the government policies responsible for that impoverishment.
18
He noted that the disease spread most rapidly in conditions of dense housing and poor hygiene, where people who lacked access to clean tap water rarely bathed or washed their clothing. The bacteria survived in such conditions, and could be passed from one family member to another via shared towels, clothing, cleaning rags, or kerchiefs.
18
He noted that the disease spread most rapidly in conditions of dense housing and poor hygiene, where people who lacked access to clean tap water rarely bathed or washed their clothing. The bacteria survived in such conditions, and could be passed from one family member to another via shared towels, clothing, cleaning rags, or kerchiefs.
By the time Mérieux had manufactured enough vaccine to immunize the population of São Paulo, the epidemic had claimed over 11,000 lives and caused serious illness in more than 150,000 people in at least six Brazilian states. About 30 percent of the survivors were reportedly suffering long-term neurological disorders of one kind or another.
By New Year's the attack rate of the disease in Rio was 205 cases per 100,000 people and authorities feared the upcoming Carnival would increase its spread. The vision of millions of Brazilians and tourists dancing together for days on end in crowded streets presented the very real possibility that the epidemic would be carried all over the planet by worn-out revelers returning home.
Though they had no idea how effective the Mérieux vaccine might be, or how dangerous, Rio officials felt they had no option: on January 13 they began a twelve-day vaccination campaign with the announced goal of immunizing 80 percent of the population of greater Rio.
Within five days, over 3 million Cariocas were vaccinated and the incidence of meningitis instantly plummeted. During the dreaded Carnival week only ten people contracted the disease.
Encouraged by the Rio experience, the military government organized the largest vaccination campaign in world history. From April 21 to 24, nearly 11 million residents of São Paulo were vaccinated, representing 90 percent of the city's population. This was accomplished by cordoning off all the commuter-intensive areas of the city and lining up as many as half a million people at a time for their shots. The entire mass media was mobilized as a huge propaganda tool for the campaign and military vehicles blasted pro-immunization announcements from roof-mounted loudspeakers.
Throughout Brazil similar militarily precise operations were soon conducted, eventually bringing the epidemic to a halt.
By early 1976, when McCormick returned to CDC headquarters in Atlanta, meningitis had ceased to be a serious problem in Brazil. But the fundamental question of where this virulent Type A strain had come from
remained unsolved. At a PAHO meeting in Washington in February 1976, McCormick pushed for inclusion of the following statement in the official summary of the Brazilian episode:
remained unsolved. At a PAHO meeting in Washington in February 1976, McCormick pushed for inclusion of the following statement in the official summary of the Brazilian episode:
Â
It is not possible at the present time to predict when and where an epidemic of meningococcal meningitis will occur. Therefore it is not clear when and where preventive immunization should be carried out.
19
19
Â
Overlooked entirely in the final PAHO report was the significanceâpossible harbingerâof the bacteria's ability to resist common antibiotics.
As was the case with malaria, polio, smallpox, and all bacterial diseases, the 1960s mood surrounding yellow fever control was one of extreme optimism. The tools were at hand: DDT and other pesticides to kill the
Aedes aegypti
mosquitoes that carried the yellow fever virus and an effective vaccine. Since 1937, yellow fever vaccines had been in use, and refined forms of immunization proved so powerful that virtually every vaccinated person was protected for life by a single shot.
20
Beginning with the period of the construction of the Panama Canal at the turn of the century, a variety of successful means had been used to eliminate the
A. aegypti
mosquitoes from the Americas.
Aedes aegypti
mosquitoes that carried the yellow fever virus and an effective vaccine. Since 1937, yellow fever vaccines had been in use, and refined forms of immunization proved so powerful that virtually every vaccinated person was protected for life by a single shot.
20
Beginning with the period of the construction of the Panama Canal at the turn of the century, a variety of successful means had been used to eliminate the
A. aegypti
mosquitoes from the Americas.
Since the seventeenth century yellow fever had been a major and terrifying scourge in the Americas, causing endemic disease in jungle and swamp areas from Canada to Chile and claiming tens of thousands of lives in periodic urban epidemics. It would begin with a headache, fever, and a vague sense of uneasiness, within hours progressing to chills, muscle pains, and vomiting. After five days internal bleeding would commence, the liver would malfunction, and the individual would become jaundiced. If never previously exposed to the virus, the human then had a 50â50 chance of dying. A 1793 yellow fever epidemic in Philadelphia killed 15 percent of the city's population and sent one out of three residents fleeing into the countryside.
21
21
In West Africa, yellow fever was so ubiquitous that most surviving adults were immune to the disease. Many historians have noted that their acute vulnerability to yellow fever prevented British and French colonialists from attaining full control over West Africa.
22
So obvious was this deterrence in some areas of Africa that it was celebrated in song and verse by people from the Sudan to Senegal. Well into the 1980s schoolchildren in Ibo areas of Nigeria still sang the praises of mosquitoes and the diseases they gave to French and British colonialists.
23
22
So obvious was this deterrence in some areas of Africa that it was celebrated in song and verse by people from the Sudan to Senegal. Well into the 1980s schoolchildren in Ibo areas of Nigeria still sang the praises of mosquitoes and the diseases they gave to French and British colonialists.
23
It was generally believed the A. aegypti mosquito originated in West Africa and was brought to the New World aboard slave ships.
24
The mosquito
quickly adapted and thrived in the moist tropical regions of the Caribbean and the Amazon. The first epidemics occurred in Mexico's Yucatan and Havana, Cuba, in 1648. In less than fifty years, the
A. aegypti
population had blanketed the Americas, and yellow fever epidemics were cropping up everywhere.
24
The mosquito
quickly adapted and thrived in the moist tropical regions of the Caribbean and the Amazon. The first epidemics occurred in Mexico's Yucatan and Havana, Cuba, in 1648. In less than fifty years, the
A. aegypti
population had blanketed the Americas, and yellow fever epidemics were cropping up everywhere.
In 1901 American Army physician Walter Reed and Cuban doctor Carlos Finley figured out the link between the
A. aegypti
mosquito, the virus, and the importance of uncovered pools of clear water, and started a hemisphere-wide effort to eradicate the mosquito. The mosquito, they discovered, could only leave its eggs in clear, clean water, so it thrived around people, lived in human homes, and left its larvae in jugs of drinking water. The insect was also constrained by temperatures below 60°F and only thrived in humid climates over 72°F. It seemed immediately obvious, then, that the entire yellow fever problem could be greatly reduced by simply covering all clean water supplies during warm months.
A. aegypti
mosquito, the virus, and the importance of uncovered pools of clear water, and started a hemisphere-wide effort to eradicate the mosquito. The mosquito, they discovered, could only leave its eggs in clear, clean water, so it thrived around people, lived in human homes, and left its larvae in jugs of drinking water. The insect was also constrained by temperatures below 60°F and only thrived in humid climates over 72°F. It seemed immediately obvious, then, that the entire yellow fever problem could be greatly reduced by simply covering all clean water supplies during warm months.
In 1927 a vaccine was developed and the first official global disease eradication effort began, endorsed by the governments of the America.
25
25
The language of yellow fever efforts shifted from “eradication” to “control” and “conquest” following Fred Soper's 1932 discovery that some monkeys harmlessly harbored the virus.
26
In subsequent years, scientists discovered that several species of monkeys and apes could carry the virus, both in Africa and in South America. In the Americas, capuchin monkeys were unharmed by the virus, but carried yellow fever and could be a source of the microbe for feeding mosquitoes. In contrast, when yellow fever hit Central America, epidemics virtually exterminated the nonimmune
Ateles
and
Alouatta
monkey populations.
27
26
In subsequent years, scientists discovered that several species of monkeys and apes could carry the virus, both in Africa and in South America. In the Americas, capuchin monkeys were unharmed by the virus, but carried yellow fever and could be a source of the microbe for feeding mosquitoes. In contrast, when yellow fever hit Central America, epidemics virtually exterminated the nonimmune
Ateles
and
Alouatta
monkey populations.
27
In short order it was also discovered that
A. aegypti
wasn't the only mosquito that could carry yellow fever:
A. africans, A. simpsoni,
and
A. albopictus
, to name a few, could carry the virus. Furthermore, the virus could be passed from one mosquito generation to the next in the insect's eggs; this allowed for long periods of timeâseveral insect generationsâwhen the disease seemed to disappear. But the virus was actually silently residing in generations of monkeys and mosquitoes, ready to reappear in human epidemic form under the proper conditions.
28
A. aegypti
wasn't the only mosquito that could carry yellow fever:
A. africans, A. simpsoni,
and
A. albopictus
, to name a few, could carry the virus. Furthermore, the virus could be passed from one mosquito generation to the next in the insect's eggs; this allowed for long periods of timeâseveral insect generationsâwhen the disease seemed to disappear. But the virus was actually silently residing in generations of monkeys and mosquitoes, ready to reappear in human epidemic form under the proper conditions.
28
The harsh significance of this jungle/monkey form of yellow fever hit home in 1949 when the disease broke out again in Panama, reversing more than forty years of successful eradication begun in the days of Walter Reed. From there it spread northward through Costa Rica, Guatemala, and Mexico, forcing U.S. military and PAHO intervention for control. By 1959 cases of yellow fever were cropping up in areas all over South America where authorities thought eradication had been successful. In most outbreaks, the first cases involved men who worked in agriculture or timbering on the edges of tropical rain forests; there, they came in contact with wild mosquitoes that fed on monkey carriers.
29
29
By the late 1950s scientists realized that there were two types of yellow
fever: the urban form associated with
A. aegypti
and the forest or sylvan form that could be found in a variety of monkeys and wild mosquitoes. Eradication of the urban form might be possible through vaccination, covering all water sources, and DDT spraying of insect breeding sites. But jungle yellow fever could not be eliminated without vaccinating all wild monkeys in Africa and South America, a clearly impossible task. Despite these hurdles of nature, WHO and PAHO remained optimistic about eliminating all human yellow fever disease because the vaccine protected people against both forms: if all children living in endemic areas were routinely vaccinated, they reasoned, the disease would only remain a threat to non-immunized foreigners traveling through jungle areas. Mass vaccination campaigns of the 1940s and 1950s drastically reduced human disease in both South America and West Africa.
fever: the urban form associated with
A. aegypti
and the forest or sylvan form that could be found in a variety of monkeys and wild mosquitoes. Eradication of the urban form might be possible through vaccination, covering all water sources, and DDT spraying of insect breeding sites. But jungle yellow fever could not be eliminated without vaccinating all wild monkeys in Africa and South America, a clearly impossible task. Despite these hurdles of nature, WHO and PAHO remained optimistic about eliminating all human yellow fever disease because the vaccine protected people against both forms: if all children living in endemic areas were routinely vaccinated, they reasoned, the disease would only remain a threat to non-immunized foreigners traveling through jungle areas. Mass vaccination campaigns of the 1940s and 1950s drastically reduced human disease in both South America and West Africa.
In the Americas, PAHO officials decided that the disease could further be prevented by eliminating the
A. aegypti
mosquito from the hemisphere, and from 1947 to 1960, the organization conducted a second massive campaign of mosquito control. In some countries, such as Argentina, Chile, Panama, Venezuela, and Colombia, DDT spraying and systematic covering of water sources radically reduced
A. aegypti
and public health officials were confident the insect could be wiped out of the Americas by the mid-1960s. But the U.S. Congress was never convinced such an effort was important for residents of the Northern Hemisphere, and, despite having formally committed itself to the PAHO campaign, never allocated funds for such an effort inside U.S. territory.
A. aegypti
mosquito from the hemisphere, and from 1947 to 1960, the organization conducted a second massive campaign of mosquito control. In some countries, such as Argentina, Chile, Panama, Venezuela, and Colombia, DDT spraying and systematic covering of water sources radically reduced
A. aegypti
and public health officials were confident the insect could be wiped out of the Americas by the mid-1960s. But the U.S. Congress was never convinced such an effort was important for residents of the Northern Hemisphere, and, despite having formally committed itself to the PAHO campaign, never allocated funds for such an effort inside U.S. territory.
Yet Congress, recognizing the diplomatic importance of appearing to comply with a PAHO edict for which the United States had voted, did order the CDC to attempt eradication. The effort was doomed from the start by hundreds of protesting property owners who threatened to sue if chemicals were sprayed in their yards or homes.
In 1964, Dr. Donald Schleissman, who led the largely unfunded U.S.
A. aegypti
elimination effort, said of U. S. congressional commitment, “The mandate to eradicate
aegypti
with the funds available was equivalent to instructions to fly across the Atlantic with half a tank of gas.”
A. aegypti
elimination effort, said of U. S. congressional commitment, “The mandate to eradicate
aegypti
with the funds available was equivalent to instructions to fly across the Atlantic with half a tank of gas.”
Though its numbers were reduced temporarily,
A. aegypti
was never driven out of the Americas.
A. aegypti
was never driven out of the Americas.
Similar campaigns were carried out throughout equatorial Africa, but five yellow fever outbreaks occurred in the 1950s. A 1959 outbreak in Zaire only came to a halt when hundreds of thousands of people had been vaccinated and more than twenty tons of DDT were sprayed over a relatively confined area.
30
In 1960 an enormous yellow fever epidemic broke out in western Ethiopia. By the time the epidemic died down in 1962, over 100,000 people had suffered the disease; yellow fever killed one out of three infected Ethiopians.
30
In 1960 an enormous yellow fever epidemic broke out in western Ethiopia. By the time the epidemic died down in 1962, over 100,000 people had suffered the disease; yellow fever killed one out of three infected Ethiopians.
A subtle change followed the Ethiopian epidemic. Without really discussing the matter, international experts slowly switched their tactics from
the bold eradication ventures aimed at wiping out the disease to fire fighting. Research outposts were set up in yellow fever hot spots worldwide by the Rockefeller Foundation and a variety of government-associated agencies.
31
the bold eradication ventures aimed at wiping out the disease to fire fighting. Research outposts were set up in yellow fever hot spots worldwide by the Rockefeller Foundation and a variety of government-associated agencies.
31
It was in such an outpost that Tom Monath, a CDC entomologist, worked at the University of Ibadan in Nigeria. Before he would leave Nigeria in 1972, Monath would travel all over the country trying to figure out where the virus hid between human epidemics. He would discover that a mosquito called
Masoni africana
could carry the virus throughout its habitat: the higher treetop levels of the Nupeko tropical forest lining the banks of Nigeria's rivers.
32
Masoni africana
could carry the virus throughout its habitat: the higher treetop levels of the Nupeko tropical forest lining the banks of Nigeria's rivers.
32
Monath's commitment to conquering yellow fever was solidified in late 1970, when he was part of a U.S.-Nigerian team that investigated an epidemic in Nigeria's savanna plains of the Okwoga District. Over the Christmas holidays, Monath and his Nigerian colleagues made house-to-house surveys of Okwoga villages and medical clinics, searching for yellow fever cases and assisting Nigerian efforts to control the epidemic.
“Has anybody here been sick lately?” Monath, a white Bostonian sporting a crew cut and smile, would ask when he arrived in a village. Time after time the scenario repeated itself: a villager would nod somberly and lead Monath into a thatched hut. There, a dead man would be sitting up straight in a chair, his eyes staring ahead, cotton plugs stuffed up his nostrils.
The first time Monath beheld such a sight it scared the hell out of him, but after a while it was not the individual cases that troubled him, but the overall level of destruction inflicted by both the disease and the treatments used in some areas to allegedly cure yellow fever.
He was also impressed by the fact that no original source for the 1970 epidemic could be found. Monkeys were scarce, there were no rain forests, yet in some villages one-third to half the residents showed blood-test evidence of recent infection. The overall infection rate in Okwoga was 14 percent, yet the most common yellow fever carrier, the
A. aegypti
mosquito, was virtually nonexistent in the area.
33
A. aegypti
mosquito, was virtually nonexistent in the area.
33
Monath and his colleagues were forced to conclude:
Â
The origin of the epidemic is not known. Two possibilities exist: (1) the Okwoga outbreak ⦠resulted from the introduction of Yellow Fever Virus from a distant source at a time favourable for interhuman transmission in an immunologically susceptible population or (2) Yellow Fever is endemic ⦠in or near Okwoga District.
34
34
Â
In other words, either the disease was brought into the area by a traveler or it was there all along, hiding somehow for decades. There was an enormous biological gap between those two possibilities. Monath realized that not knowing which explanation was correct meant there was no way to determine how best to prevent future outbreaks in the area. Or any area.
Hopes for controlling the insects that acted as vectors for yellow fever
dimmed further still, as everywhere scientists looked another insect vector for yellow fever turned up. Karl Johnson found other virus-carrier species in Panama, Brazilian physician-scientist Francisco Pinheiro identified still more insect vectors in his country's jungle interior, and U.S. Army researchers discovered that horse mosquitoes in Brazil and common ticks in West Africa could spread the virus.
dimmed further still, as everywhere scientists looked another insect vector for yellow fever turned up. Karl Johnson found other virus-carrier species in Panama, Brazilian physician-scientist Francisco Pinheiro identified still more insect vectors in his country's jungle interior, and U.S. Army researchers discovered that horse mosquitoes in Brazil and common ticks in West Africa could spread the virus.
In 1972, convinced that it was fruitless to try to eliminate yellow fever, the Rockefeller Foundation shut down Monath's lab in Ibadan and the other field stations. Years later Monath would still refer to the decision with bitterness. “A great opportunity has been blown,” he told colleagues, noting that between 1947 and 1972,
A. aegypti
had been eliminated from three-quarters of its pre-World War II habitat worldwide. Nineteen countries had eliminated the yellow-fever-carrying insect entirely by 1972, prompting the Washington consulting firm of Arthur D. Little to do a cost-benefit analysis of mounting a full-scale campaign to rid the Americas of the insect. The Little study determined that such an effort would clearly be desirable, even though the virus had a sylvatic cycle that allowed it to hide for long periods of time in wild monkeys and several other insect species. It reasoned that spending $326 million in the early 1970s to wipe out
A. aegypti
would bring human incidence of the disease down to near-zero levels in most Latin countries, because only that mosquito was infecting urban residents. Furthermore,
A. aegypti
was a far more efficient virus spreader; every major yellow fever epidemic of the nineteenth and twentieth centuries was spread by that mosquito. So, the consulting firm reasoned, a global campaign to eradicate
A. aegypti
could limit the yellow fever problem to levels entirely controllable through routine vaccination of people living or working in jungle areas.
A. aegypti
had been eliminated from three-quarters of its pre-World War II habitat worldwide. Nineteen countries had eliminated the yellow-fever-carrying insect entirely by 1972, prompting the Washington consulting firm of Arthur D. Little to do a cost-benefit analysis of mounting a full-scale campaign to rid the Americas of the insect. The Little study determined that such an effort would clearly be desirable, even though the virus had a sylvatic cycle that allowed it to hide for long periods of time in wild monkeys and several other insect species. It reasoned that spending $326 million in the early 1970s to wipe out
A. aegypti
would bring human incidence of the disease down to near-zero levels in most Latin countries, because only that mosquito was infecting urban residents. Furthermore,
A. aegypti
was a far more efficient virus spreader; every major yellow fever epidemic of the nineteenth and twentieth centuries was spread by that mosquito. So, the consulting firm reasoned, a global campaign to eradicate
A. aegypti
could limit the yellow fever problem to levels entirely controllable through routine vaccination of people living or working in jungle areas.
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