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The McConnon Strain - A mysterious outbreak of unknown spread

Posted By Lauren Reeves, Thursday, August 14, 2014
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Despite advances in healthcare, infectious microbes continue to be formidable adversaries to scientists and doctors. Deadly Outbreaks—a book of real-life outbreak mystery stories—recounts the scientific adventures of a special group of intrepid individuals who investigate disease outbreaks and figure out how to stop them.

Several upcoming blog posts will describe stories from Deadly Outbreaks, written by Alexandra Levitt. (You may recognize some of these outbreak or their causes, or you may know some of the epidemiologists. Read on to find out….) For example, this week’s post concerns an outbreak of a dangerous drug-resistant disease with the potential for international spread. Like today’s Ebola outbreak in West Africa, the dangers posed by this outbreak underscore the critical importance of maintaining local public health systems that do the day-to-day work of investigating outbreaks and stopping them at their source. We rarely know in advance which small outbreak or disease cluster will turn out to be something truly dangerous and devastating.

Here is what happens in the outbreak story entitled The McConnon Strain:
Epidemiologists sometimes face difficult choices, with moral, political, and financial repercussions that must be weighed against risks to human health. In 1983, for example, two officials, Patrick McConnon (from the United States) and Roland Sutter (from Switzerland), agonized about whether to delay the long-awaited repatriation of 20,000 Cambodian refugees, fearing that some might carry a rare, multidrug-resistant form of malaria. The U.S. Government planned to fly the refugees from Thailand, where they lived in border camps, to the Philippines (where they would be processed for entry into the United States). Stopping the flight would prolong the misery of hundreds of desperate families eager to resettle and start new lives. On the other hand, introducing an untreatable form of malaria into a mosquito-infested part of the Philippines could bring illness or death to thousands or even millions of people. As recorded in Deadly Outbreaks (page 38):

People stranded in refugee camps, displaced, impoverished, and malnourished, are at special risk for infectious diseases such as malaria, measles, and cholera that flourish in crowded and unsanitary living conditions. When infected refugees are moved to new holding sites, repatriated, or resettled in new countries, they can bring these diseases with them. As a result, public health officials like McConnon have overlapping and sometimes conflicting aims: to safeguard the health and welfare not only of the refugees themselves, but also of the people in countries that host refugee camps or accept refugees as permanent residents.

The spread of smallpox after the 1971 Pakistani civil war illustrates what can happen when a pathogen incubated in a refugee camp infects the wider population. Smallpox was carried to the newly established nation of Bangladesh by Bengali refugees returning home from India. According to public health lore, the presence of smallpox in the camps was detected by an epidemiologist in Atlanta, sitting in his living room watching TV, who noticed a man with a suspicious rash in a newsreel about a camp near Calcutta... The epidemiologist called the director of CDC, who called the director of the WHO Smallpox Vaccination Program, who called the Indian Ministry of Health. But it was already too late. Thousands of Bengalis had already left the camp, leading to widespread outbreaks in Bangladesh and making the last Asian country to eliminate smallpox.

McConnon was well aware of this history, because he had worked in Bangladesh in 1975, the final year of the smallpox eradication effort in Asia. He tried to convince an official at the U.S. State Department that it was dangerous to send refugees to the Philippines before screening them for this unusual strain of drug-resistant malaria. But the State Department official was skeptical and demanded to see some evidence.
With few resources and little time, McConnon and Sutter conducted a small-scale epidemiologic study in the border camp. If they could figure out which activities (e.g., farming, fishing, water collection) exposed people to malaria, they might delay the departure of exposed refugees while allowing unexposed refugees to proceed to the Philippines. As part of the study, they plotted the location of each malaria case on a map of the refugee camp, hoping to see a pattern. However, the data did not support any of their hypotheses. There was no association between the malaria cases and growing crops or working near the forest, swamp, chicken coops, or garbage dump. In fact, the distribution of malaria cases seemed entirely random, except for one thing: nearly all the cases involved males between the ages of 13 and 35.
This did not make sense! The mosquitoes that carry malaria do not distinguish between women and men or between the young and the old. McConnon and Sutter remained frustrated and puzzled—until they stumbled on an explanation during a conversation in a local bar when an aid worker mentioned a border-camp activity they had not tested for…
Stephen Ostroff, MD, former deputy director of CDC’s National Center for Infectious Diseases and former director of Pennsylvania’s Bureau of Epidemiology, said that “anyone with even a passing interest in disease investigation will find Deadly Outbreaks to be a great read. So too will all practitioners of public health, from students contemplating a career in epidemiology to the most seasoned veteran.” You can purchase a copy of Deadly Outbreaks by author Alexandra Levitt at

Tags:  deadly outbreaks  infectious disease  malaria  outbreak 

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