Tassy Prosser and Nathan Wolfe
in the Cameroon bush, a hunter from the village has had a good day.
He heads back to camp carrying a freshly killed duiker, a
kind of small antelope, in a rattan sling on his shoulder. Blood
from the animal drips down the hunter's bare legs, which are scratched
and cut from his trek through the underbrush. At the camp, his wife
takes the game and butchers it, accidentally cutting herself on
the sharp knife in the process.
Later, she will smoke the strips of meat over an open fire, and,
once preserved, the duiker will be sent by bus to the capital city
of Yaoundé. The exchange is part of an extensive underground
economy that provides forest game — bush meat it is called
— to the country's urban centers in exchange for cash.
It is exactly this process that research associates Nathan
Wolfe, ScD, an infectious disease expert, and his wife A.
Tassy Prosser, MS, an anthropologist, have been carefully studying.
The post-docs, working under Professor Don
Burke, have come to west Central Africa to try to discover how
new diseases enter the human population. In particular, they are
interested in how the hunting and butchering of forest animals -
including monkeys and even apes — could be a mechanism of transmission
enabling new pathogens to enter into the human population.
"I'm interested in a whole range of diseases, especially the
ones that may have the potential to move from animals into humans
but have not yet done so to our knowledge," says Wolfe. "Just
one example would be the simian hemorrhagic fever virus, which is
known to exist in nonhuman primates and is just the sort of virus
that could be an important emerging agent." It is thought that
Ebola and HIV and perhaps a number of other viral infections may
have entered the human population through just this process — blood-to-blood
contact between animal and human during some step of hunting, butchering,
Does the Cameroonian taste
for animals hunted in the wild provide an avenue for pathogens
to enter human populations?
Wolfe and Prosser spend part of their time in the field, observing
how bush meat is butchered and distributed. More often, they are
visitors to the bush villages where they oversee AIDS testing, awareness,
and education programs while collecting extensive behavioral data
about the lifestyles and activities (including hunting and butchering)
of the residents. Prosser oversees a team of four counselors who
can ask questions in either French (the language of Cameroon's colonial
heritage) or one of several local languages such as Ewando, Douala,
or Fang. "What I try to do is ensure the accuracy of questionnaire
results and then compare them with the blood test results,"
The blood tests themselves enable Wolfe to conduct what he calls
"sero-archaeology," the careful examination for trace
evidence of exposure to new and different viruses. "We're looking
for retroviruses in general," he says. "This includes
a whole range: HIV and other closely related viruses, HTLV, foamy
viruses, and others."
The scientists' research has already turned up one disquieting discovery.
"What has been an eye-opening experience is just how wide-scale
this practice is," says Prosser. "Cameroon is 50 percent
urban at this point, but there is a lot of anxiety about that urbanization.
Ask almost anyone, and he will tell you he is 'still a villager
at heart.' Often, the way urban dwellers maintain that connection
is by eating bush meat, so there is large-scale consumption of bush
meat in the cities, even though it costs more there than chicken
Although consumption of bush meat is officially discouraged — and
even illegal — the Cameroon government has not been able to put
an end to the practice. If this black market economy leads to the
introduction of new infectious agents into human populations, success
in battling them will depend to a large extent on how quickly they
are identified. "Currently, we wait for an epidemic to start
before we mobilize resources to fight it," Wolfe says. "What
we want to try to do is create a science that is predictive, that
identifies the mechanisms that enable new diseases to appear. What
we're trying to do is create the science of emerging disease."
anthrax attacks in New York was the job that took Els Mathieu (MPH
'00) into the eye of a media hurricane. But the 35-year-old Belgian
says it was a fairly routine outbreak of cryptosporidium in rural
Ohio that really gave her an insight into the American system of
public health, and how it differs from those in Europe.
An Epidemic Intelligence Service officer in the National Center
for Infectious Diseases of the Centers for Disease Control and Prevention
in Atlanta, Mathieu must be ready to leave at short notice to investigate
infectious disease outbreaks in the United States. When more than
700 people in a small rural town outside Columbus came down with
diarrhea and other symptoms typical of crypto, Mathieu was sent
as the primary investigator.
"I began working with the local health department, and I learned
that the local voters had to vote to approve their budget,"
says Mathieu. "Essentially, they [the health department] had
to compete for their funding with other departments. I found that
quite sad that people don't see [public health] as necessary."
In Europe, she observes, the public health infrastructure is mandated
and maintained by the national government.
The cryptosporidium was quickly traced to a community swimming pool
and the outbreak was soon contained. But she thinks the area residents
came away with a heightened appreciation of the need for an effective
public health infrastructure, in much the same way the anthrax attacks
made that point on a national scale.
a lifetime of public service, Luis F. Duque settled down several
years ago to enjoy retirement in his Medellin home. The public health
professor and former rector of the University of Antioquia once
served as Colombia's deputy minister of health and director of the
Colombian National Institute of Health in Bogota. Later, he was
an adviser on health policy to the nation's president. Duque, MD,
MPH '68, was ready to relax and pursue his passion of reading, good
discussion with his wife and friends, and great music (both classical
But lately he's been employing the tools of public health to help
bring about an end to the plague of violence that has traumatized
Colombian society for the past several decades. Call it a semi-retirement.
Now a senior adviser to a nascent violence prevention program at
the University of Antioquia's School of Public Health, Duque and
his colleagues are planning a new effort to apply science to the
understanding and control of deadly human passion.
"Violence has been the leading cause of death in Colombia for
15 years," Duque says of his country's extraordinary murder
rate. "Fifty percent of healthy years of life lost in Medellin
are lost through homicide. That
loss is equal to the amount of healthy years lost to all other causes.
We're just starting to research into why this is so."
Although the country has been engaged in an on-again, off-again
civil war with insurgent groups such as the Fuerzas Armadas Revolucionarias
de Colombia (FARC), Duque maintains that only about a fifth of the
nation's violent deaths are the result of armed conflict. "Eighty
percent of the problem is everyday violence such as criminals with
handguns," he says. "Our murder rate is not a political
problem, it's a public health problem."
Last year, about 4,000 people were murdered in Medellin, a city
of more than 2 million. "Currently, the murder rate in Medellin
is 180 homicides per 100,000 people," Duque says. "That
compares with a rate of 40 to 50 per 100,000 in Bogota, and between
10 and 12 for the United States." About 90 percent of the violent
deaths are from guns, a change from two decades ago, when only about
half of all murders involved firearms.
"Clearly, alcohol, psychotropic drugs, and the availability
of guns all play a role," Duque says. "But these are factors
I would label instrumental. I don't think that the guns by themselves
are the cause."
Rather, he cites a culture mired in profound social and economic inequity,
a mass media both domestic and international that seems to glorify
violence and vigilantism, and an erosion in traditional cultural values.
Great changes in the family and educational system, he believes, have
created the cultural and social conditions that have made possible
the narcotics traffic that has brought Medellin worldwide attention.
In a city with a devasting
murder rate, Luis Duque hopes to guide young people to solve
problems by talking, not killing.
"Now there is a crisis in values," he says. "We need
to rebuild the societal values structure starting from some basic
values, which can be accepted by the community as a whole."
There are signs of improvement. In the past decade, Medellin's murder
rate has been cut in half. Duque hopes the university's new program
in violence prevention will help further such progress. But with the
city's unemployment rate at 20 percent, crime is an ever-present fact
of life, particularly among the city's poor. "Our challenge is
to work with children and young people to create a new cohort in society
that works out its differences without resorting to violence,"
been nearly 60 years since Johns Hopkins physician and researcher
Leo Kanner first described autism. A pervasive developmental disorder
generally diagnosed when children are young (between 18 months and
5 years of age), autism is characterized by absent or delayed language
skills, profoundly hindered social interactions, and oftentimes
rote and repetitive behaviors. Both the etiology and epidemiology
of autism are poorly understood. For decades, the neurobiological
disorder was thought to be rare — somewhere on the order of 5 cases
per 10,000 people. But in recent years that number has been going
up, raising speculation and concern that autism is becoming more
"Researchers are leaning today toward a prevalence estimate
of 10 to 30 cases of classic autism per 10,000," notes Craig
Newschaffer, PhD '96, assistant professor of Epidemiology. In
addition, he says, perhaps two to four times that number fall within
the range of Autism Spectrum Disorders, or ASD, in which some of
the behaviors of classic autism are not present, or occur in a milder
form. No one knows if these increased numbers, which are substantially
higher than the estimates of 25 or even 10 years ago, reflect increasing
risk or simply better diagnosis and reporting. Newschaffer hopes
to find out.
In October the School announced the creation of the Center for Autism
and Developmental Disabilities Epidemiology, or CADDE, with Newschaffer
at its head. One of four such Centers of Excellence for the study
of autism funded by the Centers for Disease Control and Prevention
(CDC), it is the only one focusing on the interaction between genetic
and non-genetic factors and their possible link to autism. The CDC
has committed more than $2 million over the next five years to CADDE,
which will enable Newschaffer and other researchers to conduct an
extensive surveillance project in the Delaware/Maryland area to
better estimate ASD prevalence. CDC funding will also support a
large multi-site, case-control study in which CADDE will focus on
possible links between ASD, genes that influence immune response,
family history of autoimmune disease, and prenatal infections. In
addition, the Center will serve as an information resource for parents,
physicians, and other researchers.
"If there has been a real change in ASD risk over a relatively
short period of time, that suggests there is some non-heritable component
involved somehow in the disorder," Newschaffer says. CADDE will
undertake to identify a likely culprit. But what that component might
be, and how it relates to an individual's genetic susceptibility to
autism, is unclear. Autism is known to have a large heritable component,
yet despite a decade of intense search for the gene or genes responsible,
"we still don't understand the underlying causes."
With a long career in
Epidemiology ahead of him, Craig Newschaffer changed his research
priorities after his son Jonas was diagnosed with autism as
Genes and environment are a potent mix in human health, as researchers
in cancer have come to learn. Newschaffer began his own career in
cancer epidemiology, a background he says may prove uniquely useful.
"In cancer epidemiology we acknowledge this gene and environment
interaction," he says. "It strikes me that the tools developed
there could be successfully applied to autism."
He might have stayed with cancer research, had not his first child,
Jonas, been diagnosed with autism while a toddler. "He was behind
in language development so we were having his hearing tested,"
Newschaffer recalls. "At a party a pediatrician friend saw him
and suggested that the problem might be something other than hearing
loss." Jonas is now 9. "It took a few years for me to decide
that I wanted to move into autism research," Newschaffer says.
"There were few epidemiologists at work in this field. I saw
a real need for population-based approaches. I want to help try to
get a handle on these apparent trends."
High in the mountains of Gansu Province in China's northwest, Christy
Fong (MPH '99, PhD candidate in International Health) is at work
tracking down a familiar killer. In her efforts she relies upon
the project's jeep, a skillful driver who knows the unmarked roads
and local language, and a steely sense of determination. "I'm
here because of my passion for helping my country's poor and ethnic
peoples," she says.
Despite tremendous advances in the control of infectious diseases
made in the 1950s and '60s, China still battles one of its most
persistent and deadly foes: tuberculosis. "TB was rampant in
the 1930s and '40s , and was one of the primary killers in China,"
says from her office in Linxia City, China's "Little Mecca"
and home to some 800,000 Muslims. "In the early days of the
People's Republic there was a strong effort to control TB and other
infectious diseases that was very successful. But then the emphasis
moved to other health issues and economic development, and in recent
years, with the great increase of inter-province migration, the
frequency of transmission of TB has increased significantly."
In addition, China has become one of the world's 'hot spots' of
emerging drug-resistant TB strains."
Fong is a health technical consultant for a TB control project sponsored
by World Vision, an international Christian relief and development
organization. She is helping initiate the TB program among the Muslim
Dong Xiang ethnic minority, a group that has suffered a high prevalence
of TB for many years. In particular, she is working to bring improved
TB care to the women of the district, who have typically been disadvantaged
by lower educational levels, language barriers, social customs,
and remoteness, all of which have limited their access to government
of Fong's time is spent crisscrossing Dong Xiang County, visiting
women TB patients in their homes to collect information and monitor
adherence to the 6 to 8-month treatment regimen that involves four
or more TB drugs. The other half she spends directing the project
and training local health workers. The project's five-township target
area is largely semi-arid and mountainous, ranging in elevations
from 2,000 to 3,000 meters, and houses tend to be scattered at great
distances. Fong is battling tuberculosis one case at a time, while
organizing a community-based effort to create a sustainable program
of TB control.
"What we are trying to do is enable these patients to become
change agents in their communities," she says. "Other
people will tend to listen to the experience of patients who have
been cured. By this we hope to create a rippling effect that will
amplify our efforts throughout the county."