I hesitated before swatting the mosquito on my
ankle. It’s not that I like
mosquitoes or I have some weird masochistic fetish about itching and things
sucking my blood; I wanted to identify it. It was an Aedes aegypti, the species known to transmit the disease yellow
fever.
| Aedes aegypti on my finger |
Yellow fever is a virus
that manifests itself in the same way that zombies or the “possessed” are portrayed
in horror movies. The initial stage begins with the common “flu-like” symptoms
that are characteristic of many viruses, but then the disease rapidly
progresses and the tell-tale symptoms present themself. One of the first signs/symptoms
that distinguish yellow fever is intense body pain, often described as if your
body is being slowly broken in two. This pain is often accompanied by pronounced
psychiatric symptoms such as extreme irritability with restlessness. Soon after,
your eyes go bloodshot and the liver begins to fail. This progressive liver
failure causes jaundice, the yellowing of skin and eyes, for which yellow fever
gets its name. Around this time, hemorrhagic
symptoms occur and blood usually begins to ooze from the eyes, nose, gums, and
mouth. In its final stages before death, internal hemorrhaging spills blood
into the gut causing the characteristic “black vomit” clinically known as
hematemesis. I find this progression easy to visualize due to such movies as The Exorcist and 28 days later. Think about it: the yellow skin, violent jerking,
projectile black vomit, irritability, weeping blood – if I were living in the
days before “germ theory”, I could see someone
calling a priest to “exorcise the demons”.
Yellow fever is a vector-borne
disease, meaning that it is not directly
transmitted from human to human. In fact, in the early days of research people
would volunteer to sleep in the black vomit covered beds of yellow fever
victims in order to further the scientific knowledge of this disease’s
transmission. In order for this virus to be spread, a vector is needed; in this case the vector is the mosquito. I have
never actually seen a person suffering from yellow fever and I’m thankful for
that. The vaccine and persistent vector control measures have done a good job
of subduing this disease. Nevertheless eradication is nearly impossible because
the virus has a reservoir. In terms
of infectious or communicable disease, a reservoir is an organism where a
disease can live and multiply while waiting to be transmitted to another
population. In the case of yellow fever, the reservoir is certain species of monkeys.
In forest and logging cultures there are oral traditions that warn of the
dangers of felling a “quiet” forest. This is because mosquitoes that kill
monkey populations with yellow fever remain infectious for their lifetime. Thus
logging activities can easily bring those mosquitoes to ground level,
subsequently causing an outbreak.
Prior to joining the
Peace Corps, I worked with the San Diego County Vector Control and Surveillance
Program (SDVCSP). Although there has not been a large outbreak of yellow fever
in the Americas for over 50 years; San Diego and much of the U.S. battles with
periodic outbreaks of mosquito-borne encephalitis viruses, such as: West Nile
Virus (WNV), St. Louis encephalitis (SLE), and eastern equine encephalitis
(EEE). This class of vector-borne fevers has the potential to be life
threatening in vulnerable populations; however, many healthy adults that are
infected only suffer from a flu-like illness and recover without out knowing
they ever had it. Some others become very ill and die.
The study of vector-borne
disease transmission is fascinating and plays a much larger role in human
history than many realize. For example, when Philadelphia was the capital of
the U.S. it was completely abandoned due to an outbreak of yellow fever where it
has been estimated that ten percent of the city population died. Legend has it
that even George Washington fled the city in fear and that he alone returned on
horseback to pronounce the city safe again (for more read: Bring Out Your Dead by J.H. Powell). The slave revolt on the Amistad is speculated to have happened
because many of the captive slaves had acquired immunity to yellow fever in
their childhood, while the slave traders had not. Likewise, many of the
important battles in world history were decided based on who was hit hardest by
a mosquito-borne disease, mainly malaria. During WWII, General Douglas
MacArthur said himself that at any given time, two-thirds of his fighting men
in the South-Pacific were debilitated by malaria. In response MacArthur would
seek the aid of Dr. Paul Russell, the leading expert on vector-borne disease.
After a rapid assessment, Russell found that the military had all it needed
(training, prophylaxis, etc.) to effectively combat malaria. However those who
were trained in the task of fighting mosquitoes were seen as peripheral to the
war effort. In addition he noticed troops were not taking their prophylaxis.
Russell’s basic recommendations were that commanders be responsible for troops
taking the malaria prophylaxis and mosquito fighters be given logistical
priority. MacArthur issued an executive order based on these recommendations
and soon after the malaria rates declined and US troops became healthier than
their foes. (For more read: Mosquito,
Speilman and D’Antonio, 2001)
| Anopheles larva in the village |
| Showing the children |
So as a
fieldworker and Volunteer in the United States Peace Corps what exactly can I do to help?
What
most fieldworkers do is to go to the field with a grounding in the theory of the
discipline, especially in the sub-area of their interest, and with as much
knowledge of the region as can be derived from secondary material. The field
then takes over, and the outcome depends on the interaction between the
fieldworker and the field. (Srinivas et al., 1979 pg. 8)
… and especially
the rural people who live there.
Only
three-months in and I’m starting to understand the Peace Corps mantra: “The
hardest job you will ever love”
It is and
will be challenging work. I have been educated and trained for this. I have
many “sub-areas” of interest that relate directly to present issues of
environmental health, anthropology, and development; but most importantly I
take comfort in the fact that I enjoy
what I’m doing.