and Prevention Materials
"Lassa" Online Video Documentary
documentary, produced by Special Pathogens Branch, reviews the 16-year
collaboration between the CDC and the government of Sierra Leone to control
Lassa fever in West Africa. Filmed primarily in Sierra Leone, the
full-color video looks at the disease, the tragedy it causes, and tells
the unfolding story of the epidemiology, natural history, and control
of Lassa fever through the work of the Lassa Fever Project set up by CDC
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a hardcopy of "Lassa"
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Everybody loves a parade! But this procession through the streets
of Segbweme, Sierra Leone, isn't celebrating a national holiday. These
people in this West African village are learning how to combat Lassa
fever, a deadly disease that is taking the lives of their family and
friends; a disease that threatens the lives of health care workers
throughout West Africa each day. This festive atmosphere contrasts
sharply with the stories these people can tell.
background sound; patient's heavy breathing.*
sound; health workers talking.*
My wife was first treated for malaria, and after three days, we brought
her here to the hospital at Segbwema. I know about Lassa fever and
I am very, very worried. We have five children, and the baby is so
young, and very close to his mother. They told me not to bring the
children here so they are with a friend. Who will care for them if
she dies? I must put my trust in God...
The history of Lassa fever began in 1969 with the mysterious death
of two missionary nurses and a near fatal illness of a third. The
virus isolated from two of these patients was named "Lassa"
after the town Lassa of Nigeria where the disease was first recognized.
The disease was called "Lassa fever."
Pinneo, an American nurse working at the Brethren's Mission station
in Lassa, Nigeria became ill after caring for two other nurses who
died of the disease. When she too, developed a 103-degree fever and
severe ulcers in her mouth, she was flown to Columbia-Presbyterian
Hospital in New York.
Doctor John Frame, a scientist at Columbia University caring for
Ms. Pinneo, sent blood samples to the Yale Arbovirus Research Unit.
Meanwhile, a research team at Yale University headed by Dr. Wilbur
Downs which included Dr. Jordi Casals began studying the blood samples
of these three missionaries. A few months after his work began, Casals
came down with the disease. Both Dr. Casals and Ms. Pinneo survived
Unfortunately however, Mr. Juan Roman, a laboratory technician at
Yale with no known contact with the virus, contracted the disease
and died in December 1969.
Thomas Monath: There was a suspected outbreak of Lassa in the
eastern province of Sierra Leone. The outbreak was centered in a Catholic
missionary hospital in Pangama. But it was apparent early on that
this was not a typical nosocomial outbreak and only a small fraction
of the cases could be traced to infection acquired in the hospital
In fact, most of the patients became infected in their own village.
Dr. Monath, with other scientists from the Centers for Disease Control
and Prevention and Yale University and the Ministry of Health of Sierra
Leone, began a systematic study of animals from patients' homes to
determine the carrier of the disease. Hundreds of animals, particularly
rodents, were collected from the village and surrounding areas. Several
strains of Lassa virus were isolated from a small gray rodent found
living in the houses, implicating it as the reservoir host. Since
this discovery, several other studies have been carried out in West
African village settings confirming the transmission of Lassa virus
to man from this common village rodent, scientifically called Mastomys
In 1976, Dr. Karl Johnson of the CDC in Atlanta Georgia, sent Dr.
Joseph McCormick and a medical team to West Africa to begin extensive
research to answer the critical questions surrounding Lassa fever.
Through the combined efforts of the CDC, the Ministry of Health in
Freetown, Sierra Leone, and the Nixon Memorial Hospital in Segbwema
with a very capable Sierra Leone medical staff, a research unit specifically
aimed at studying and developing a treatment to Lassa fever began
to unravel its mysteries.
One of these early pioneers was Dr. George Komba-Kono, a native of
Sierra Leone who sat as research physician of the Lassa Research Project
from 1978 to 1982.
Komba-Kono: First of all, the ideas of Thomas Monath and others
came in very handy, because they gave us the background information
on which to set up any control screening situation. And so Joe McCormick
was the principle actor behind it all. He set up the lab and brought
in all the equipment and so on and did the public relations because
accepting a new program like that can be quite problematic. People
didn't understand, they just knew there was fever that went with all
the 'meets/meats' and 'mights/mites' around the fever, witchcraft
and all, you know. So it was an enormous problem setting up the lab
and also, getting the people to understand what it was all about.
Joe McCormick was succeeded by Dr. Patricia Webb. I worked directly
under the supervision of Dr. Patricia Webb as director after Joe had
In the early stages, the symptoms of Lassa fever are often misdiagnosed
as influenza, typhoid fever or malaria. As a result, many patients
fail to get appropriate medical attention in time.
Susan Fisher-Hoch: Patients in the early phases in the sort of
environment where this disease occurs won't go for medical care until
they are really sick because they cannot afford much in the way of
medical care. So, unfortunately, they don't present until they are
very much sicker and this makes it more difficult to treat and also
means we see the disease at a more severe stage. So by the time the
patient comes to the hospital they will be very weak, they will have
a high fever, they will have considerable pains and they may have
nausea and vomiting.
Lassa fever can be very difficult to diagnose, even by people who've
seen many hundreds of cases and this is because it can present in
all sorts of different ways. But, in general principle, after an incubation
period of between 1 to 3 weeks the patient will become febrile, have
a fever and not feel very well quite simply. They may have a headache
and then develop a series of other body pains such as abdominal pain,
chest pain, general muscle pains or pains in the joints.
Patients also frequently develop a sore throat; this can be very severe
pharangitis. Then if you look at the throat it will be inflamed and
they may even have exudate. And some patients will have such pain
in their throats that they refuse to swallow or try not to swallow.
Then some patients will then get better at this stage and they do
very well. But some others, a small proportion, will become very sick
and they go on to start to get increasing nausea and then start to
vomit and develop diarrhea and then they will go into shock. Sometimes
they have bleeding, sometimes they have respiratory distress and sometimes
they will have convulsions or fits and sometimes they will bleed and
these patients very frequently die.
Lassa fever is particularly dangerous for pregnant women. Lassa infection
is fatal to the fetus in more than three quarters of the cases and
produces a high mortality in the mothers, especially in the last trimester
Aniru Conteh: If they contract Lassa fever within the first trimester,
usually the fetus dies; they abort, these women abort and then usually,
they generally recover after that. However if they come in the late
trimester, say about the third trimester or the second trimester,
it is generally very difficult for them. We have found that most of
them in the late pregnancy do die along with the baby; we usually
Lassa fever was a surprisingly important cause of illness when two
West African hospitals were studied over a five-year period. 12 percent
of adults, that is more than 1 patient in 10 admitted to the medical
ward had Lassa fever. A third of the deaths in those wards were from
Lassa. Similar statistics apply to the children's wards.
Joseph McCormick: Lassa fever gets transmitted to humans in two
different ways. One way is from the urine of the rodent Mastomys
natalensis, which is the common rodent called the "multi-man"
rat that you find throughout much of Africa, as a matter of fact,
but especially in West Africa. This rodent tends to live in houses
with humans. It will live there for long periods of time. What usually
happens in West Africa the people wake up in the morning, they get
a bit of breakfast and then they close their houses up and go off
to their day's activities. Of course when they come back in the evening,
it becomes dark at 6:30pm or 7pm and what this means for the rodent
is that it has sometimes almost 24 hours of night time activity. During
that time the rodent will circulate through the house and deposit
urine on surfaces such as the floors, the tables, and even in food
if the rodent is able to get into the food and other places even on
beds. And we believe that people get infected most frequently when
they come into contact with the deposited rodent urine on one of these
surfaces and is usually gets transmitted through cuts and scratches
on their hands and feet.
Aniru Conteh: Lets look back at tradition. Sierra Leonians have,
over the centuries, known rats. They've known all types of domestic
animals that live with them in some of the villages. The people trap
rats, kill them either for food or other purposes. But to come right
back and say that the rat which lives with you, in your farmhouse,
is responsible for the spread of a deadly disease like Lassa; that
was too hard for the people to swallow. And so we took a whole lot
of maverick in education to get the people to really understand that
this was really so. I think that was one of the areas where we found
a whole lot of problems. A typical example is like in the mining areas
where we go to trap the rodents in their houses; we talk to them and
they allow us to put the traps. When we leave they through the traps
out. The next day you come, you think you are going to have a catch,
your trap is not there and it is by the house. Those are the things
that we went through.
But then keep pointing back on the dedication of our staff, they didn't
get frustrated and pull out. Instead they would talk and talk to those
people again and reset the traps and eventually people got to accept
McCormick: Now the second way people can get infected is from
person to person. This occurs we know within households, within family
units, especially when one person is taking care of someone else.
You have a person who's ill, who's bed-ridden, they may be vomiting,
they may even be bleeding for this disease can cause bleeding, and
when they take care of this patient and come into direct contact with
secretions from that patient they are at risk for getting infected.
And we know that that is the second way that people can get infected.
Now this can also obviously affect hospital personnel because if someone
comes into the hospital with Lassa fever and someone takes care of
them, the person who is taking care of them, whether it be a nurse
or a physician or someone else in the hospital, is also at risk if
they don't take precautions of getting infected from that person.
The necessity of health care workers using strict barrier nursing
measures became a critical factor in preventing the spread of the
disease. Hospital staff are trained to wear gloves, masks and gowns
while caring for Lassa patients as well as disinfecting reusable materials
and destroying all refuse materials that are used in caring for Lassa
The close contact required between health care workers and patients
while delivering babies or performing autopsies or surgeries makes
these health care procedures particularly dangerous to the medical
staff. Health care workers must be aware that appropriate precautionary
measures minimize the risk of contracting Lassa fever and the possibility
of spreading it in the hospital. At the same time, the Lassa fever
team has made an enormous effort to provide educational programs that
inform citizens about prevention of the disease.
Perry - U.S. Ambassador: So you find that traditional people look
at Lassa fever as inevitable, "its going to infect one of my
children, I won't be able to prevent it, and it's a sad thing but
'Insh'allah', you know 'whatever Allah wishes.'" When I first
learned myself about Lassa fever it was, for the most part, from people
who lived in this country who were so happy that now you don't have
to die from it. There is a place you can go, people understand what
it is and they are teaching us what is causing it and they were trying
to prevent it.
Dianne Bennett: When we come into contact with other villages,
when we travel, we've always done a lot of health education. We tried
to focus that energy, add to it, and formalize it a bit. We brought
in a VSO, a very clever community arts worker who'd done a lot of
education, who ran some puppet shows, organized some dramas, got a
disco tape of songs about everything we knew about Lassa fever and
all these things were very very widespread. We must have dramas in
30 different villages total.
fever song *
So the question becomes, how well does information in preventing Lassa
fever translate into modified behavior for people living throughout
the villages of West Africa?
Komba-Kono: I mean attitudes are not easy to change over night
and that's why there is a long time span. But one could easily see
that it took time for people to understand and accept first of all
that the rat caused the disease. Because they will ask the questions
like 'Well why doesn't the rat die? Why do we die?' I mean a rat is
a rat is a rat. 'Why do they live and we are dying from the disease
that they carry?' and obviously that took complicated explanations.
Once the educational efforts are widespread, people recognize
the potential of Lassa fever to cause problems and they seek help.
Dr. Dianne Bennett, director of the project in 1986, recalls answering
one such request from a chief of a village where 15 people had recently
died of Lassa fever.
Bennett: These people recognized Lassa as an entity different
from malaria and other things they were dealing with because they'd
had a lot of cases in the village and some prominent people had died,
the school teacher's wife for instance. We went in and did our usual
sort of education program. We also thought this would be a good village
in which to do a study both because we could help the village while
we did the study and because we would have the help of the chief,
the school teacher and other prominent people in the village and so
that we could get a good study done.
In this farming village, questions were asked to determine what activities
of the villagers might make it more likely for them to become infected.
The probability of Lassa infection was increased in people who had
close contact with a Lassa patient, such as caring for a sick person,
including contact with blood or secretions. Sexual contact with a
person ill with or recovering from Lassa fever was also a risk factor.
People who caught, prepared and consumed rodents were at a significantly
increased risk of the disease. Older people in the village also suffered
These research results confirmed the ideas of the study team and emphasized
a message 'don't eat rats.' The rodent reservoir of Lassa virus only
invades rural villages but is common in other settings such as the
towns in diamond mining areas. There it is thought that the storage
of food in houses, instead of storage sites in the fields, brought
rodents into the crowded homes.
The saliva, urine and feces of the rodent contain the virus and may
infect man from small droplets dispersed into the air. People are
cautioned to decrease their contact with the rodents, by trapping
the rodents in their homes and particularly by keeping food covered
or in closed cabinets. In villages where these precautions were taken,
fewer cases of Lassa fever were seen.
The chief of the village Mahei Musa responds to the help the Lassa
Research Project workers brought to his people.|
Chief (voice over): I have been the chief of Peje-Baoma for 6
years. Several years ago I had Lassa fever and went to the hospital
at Segbwema for treatment. Lassa is a very difficult disease, some
people live, but many of our people have died and your research has
helped us to know it is happening so that we can totally eradicate
Lassa. It can strike anyone, but the greatest danger is to pregnant
women. Thank you for bringing people to help us, we are so happy you
Lassa fever affects everyone in the community and the more that people
know what can be done, the more hope they have that medical research
will develop a vaccine to prevent the disease totally. This schoolteacher,
who lost his wife to Lassa fever, expresses his hope of scientists
finding a cure:
My wife died at Segbwema, but it was not the fault of the Segbwema
people, it was the fault of the Panguama- who did not diagnose the
sickness in time. My son was, there are two of them my children, my
sons, but after having experienced the death of my wife being caused
by Lassa, I rushed the older one to Segbwema, directly, not by the
majestry, but to Segbwema, and he survived. So I am asking the American
government to please continue to help us to eradicate this bad disease
from this area, not only Sierra Leone, but to the entire country so
that it cannot spread.
At the urging of the Panguma community the Lassa Fever Research Project
joined forces with the Daughters of Charity Catholic Hospital to open
a diagnostic and treatment ward in Panguma. People are beginning to
understand that Lassa fever, once a feared deadly disease, may one
day be eradicated.
People are beginning to understand that Lassa Fever, once a feared,
deadly disease, may one day be eradicated...
Susan Fisher-Hoch: We have made a vaccine and we are able to test
it in animals in the laboratory in America. It seems to work very
well. But the problem now is that we have to get this medicine and
this vaccine and make sure that it is safe in people, not just in
animals, but in people.
Dr. CJ Peters, the new head of Special Pathogens at CDC, was a key
scientist in developing and testing of a vaccine against a related
disease occurring in Argentina. He is optimistic about the Lassa vaccine,
but cautions that a vaccine for the Argentine hemorrhagic fever took
ten years from beginning work until it was actually shown to be safe
CJ Peters: Lassa fever belongs to the family of viruses called
arenaviruses, and there are several other arenaviruses that cause
human disease including a virus that infects rodents in Argentina
and results in considerable problems in the rich agricultural regions
of the pampas. It was possible to develop a conventional live attenuated
vaccine against that disease and that vaccine has now been used in
one hundred thousand people in the endemic zone. That first arenavirus
vaccine used in man, and is shows that we can protect against these
diseases with vaccines. We hope that with advances in understanding
of the immunology of these viruses and the enormous power of molecular
biology, we will be able to develop a safe and effective immunogen
for the people of West Africa within perhaps 5 years, that would be
1997. I think we will need 1 or 2 years to develop and select a candidate
immunogen, 1 or 2 years to show that it really works in experimental
animals, including monkeys, and 1 or 2 years to do the initial testing
in U.S. volunteers. Then we will be able to the people of West Africa
and ask if they will work with us to show that the vaccine can prevent
Lassa fever right there where it is such a terrible problem. Of course,
this goal could take longer if scientific problems arise or if we
fail to obtain financing for the large-scale production and testing
of the vaccine. While all this is going on in Atlanta, there are lots
of things to be done in Africa as well; we have to work to blunt the
impact of the disease through the control of the rodents and the improvement
of treatment, although these measures cannot really eliminate the
disease, given the abundance and habits of the rodents that carries
the virus to man. We also have to perform the human immunologic studies
needed to evaluate the protective efficacy of the vaccine and the
additional epidemiological studies that we will need to plan the first
use of this vaccine. We have to show for all the world that the vaccine
will really prevent Lassa fever, that's the only way to get everyone
behind the effort to use the vaccine in the field the way it should
Meanwhile, only one drug is available to treat Lassa fever - ribavirin.
The use of intravenous ribavirin decreases the mortality rates of
severe Lassa fever particularly if started in an early stage of the
disease. But the drug is expensive and unavailable to most West African
hospitals. A vaccine to prevent what has been estimated to be an excess
of 250 thousand case of Lassa fever per year remains merely a hope,
and that hope is especially pertinent for people like this young mother
who suffers with one of the most severe complications of Lassa fever
Deafness usually occurs just as recovery is underway. Almost 1/3 of
the hospitalized Lassa fever patients develop an acute hearing impairment,
and approximately 2/3 of these are left with some degree of permanent
mother (voice over): Almost three months after I began to get
better, I heard a constant ringing in my left ear. Now I can hear
with my right ear, but not my left. I'm so happy to be well, so whenever
I find someone with symptoms of Lassa, I tell them to go to the doctor
Deafness was first reported as a complication of Lassa fever in 1972.
Clearly, many people with deafness from Lassa fever are not admitted
to the hospital; strongly suggesting that Lassa fever may be responsible
for a significant incidence of hearing disability. Research evaluations
of deaf people have confirmed that Lassa virus infection is by far
the most important factor associated with sudden onset deafness.
Austin Demby, the associate director of the Lassa Fever Research Project,
often hears the frustrations of people who are to cope with the aftermath
of Lassa and its altering affects upon their lives. This father is
facing the reality of his young daughter's total deafness as a result
of her battle with Lassa fever:
I am tired, I can hardly do it now in a hurry because there is no
assistance. And my child is there sick at heart and because she cannot
hear. She cannot enjoy any dance - she used to be a very good dancer.
But now I cannot remember when she last left the home because of the
sense of hearing. You see now she used to be a promising star among
our federal guard but now she's downstairs. This is a pain in my heart.
I have no way to help her.
The obvious question remains, just how widespread is Lassa fever?
Peters: We know that the rodents that carry Lassa fever thrive
all over sub-Saharan Africa and are an important pest for agriculture.
These rodents belong to a genus the experts call Mastomys,
the common name is the multimammate rat - these dozen or so nipples
are used to suckle the many offspring they produce each season. If
you display the distribution of the Mastomys genus on a map
of Africa, it involves practically the entire continent. Currently,
Lassa has been identified as an important disease problem only from
several countries in West Africa; Guinea, Sierra Leone, Liberia, and
Nigeria. But we suspect that there are problems in Savannah and cleared
forest in many neighboring countries. Our additional concern is that
there may be Lassa-like viruses in other countries such as Central
African Republic, Zimbabwe, and Mozambique. Furthermore, the wide
distribution of the rodents that may carry Lassa virus, suggest the
possibility for spread of the virus, a problem that has occurred progressively
in Argentina over the last 20 years. The overall problem is aggravated
by the progress that is being made in transportation; as Africa increases
internal trade, the possibility of movement of infected rodents is
a real danger. We can also predict that among the many travelers to
and from Africa, some possible Lassa cases will be included. So I
believe that in the future we will see more frequent introductions
of the disease to non-endemic areas, not fewer introductions.
On February 1, 1989, an American engineer, who was born in Nigeria,
returned to Chicago after attending his mother's funeral. She has
supposedly died of malaria. Tragically, on February 16, he died of
a flu-like illness in an American hospital. The diagnosis of Lassa
fever was confirmed post-mortem.
As our world grows increasingly smaller and interdependent, the urgency
for finding solutions for Lassa fever becomes a global issue. The
dedication of health care workers and researchers like those in the
Lassa fever clinic in Sierra Leone have implications far beyond the
areas of West Africa where the disease is currently endemic.
Demby: Well we started out in Segbwema a four person team, and
now we have expanded to about 32 members of staff. When we came out
we had specific questions we wanted to answer, primarily what the
natural history of the disease is, we were also trying to find a specific
therapy for the disease, and we were trying to work out a way of preventing
the disease. So far we've done a lot about therapy; now we have a
very good curative drug, ribavirin. We have known a lot about the
natural history of the disease, the transmission dynamics and the
results of that. We've studied the education component of our research,
of our project, which deals with translating all the science we know
about transmission to the general public and use it as a basis of
preventing the disease.
We are at the stage where we are about to get a vaccine ready for
field trial, which is everybody's dream. Hopefully if the vaccine
comes out and works very well, we will have reduced the prevalence
of Lassa fever in the eastern province to a minimum.
And it shows a major commitment on their part to come out and work
with what was known to be a really deadly virus. And I feel very impressed
by the output because people are very committed - from the cleaner
we have in the lab, to the director. Nobody works 40 hours a week,
people work an average 70 to 80 hours a week with no complaining at
all and we've seen lots of people come here who are very sick to the
point of dying and my biggest pride and the biggest reward I ever
get is seeing them walk out of the hospital well and see them again
after 1 or 2 months as healthy as ever, or even healthier than they
were before they got sick. That's really, that's the biggest reward
we ever get in this job in Lassa.