A second major sanitation-related disease is malaria. A
serious resurgence of
malaria is taking place in many countries. Between 300 and
400 million people
suffer from malaria, and five million die from it annually.
The disease is caused
by the malaria parasite, Plasmodium falciparium (and three
species), which are transmitted by anopheline mosquitoes
from an infected person
to a healthy person. Tropical and subtropical regions of the
world suffer the most
COMMUNITY PREVENTIVE MEASURES
Mosquitoes generally stay within about one mile (1.6 km) of
where they hatch.
The cycle from egg laying to hatching as mosquitoes usually
takes about eight
days. These facts make it easier for local mosquito
eradication or control
programs to be effective. But over time, persons infected
with malaria can visit
the local area or mosquitoes carrying the malaria parasite
can be brought in with
vegetable baskets, water containers, etc. Therefore, to be
programs must be ongoing, and any spraying should be done on
a regular basis.
Other community based anti-malaria activities include:
o Eliminate or
reduce the amount of stagnant water near the community by
ditches. The malaria mosquitoes must have water for their
egg, larval, and
pupal stages of development. Even small accumulations of
water, as in
wheel ruts or hoofprints of cattle may increase mosquito
breeding if the
water remains a week or more.
o Plan for the
elimination of standing water in new water and flood control
"Supercharge" unlined irrigation ditches about every 6 days.
To do this, raise
the water level
of the irrigation ditch three inches (8 cm) or more for a
period of about
an hour. This will cause mosquitoe larvae to float upward on
that lines the ditch. Do this in the morning on a sunny day.
Then quickly drop
the water level about five inches (13 cm.) or more and
leave it at this
level for several hours. The mosquito larva will be hung up
on the dry
vegetation and will die.
o Develop a
voluntary reporting system for persons in the community who
so that health care can be provided to them, and so that
trends in the
occurrence of malaria will be evident.
Mosquito-eating fish can reduce the number of mosquitoes in
rice fields. This is
not practical where rice cultivation includes alternate
flooding and drying.
Regular use of mosquito-proof bed nets by all or most
community inhabitants has
been shown to reduce malaria rates. Programs with community
local production and repair of bed nets deserve field
PERSONAL PREVENTIVE MEASURES
To reduce the probability of malaria:
1. Inspect your
living and sleeping quarters and install or repair screens in
2. Spray the walls,
floors, and ceilings of your residence with insecticides.
3. Sleep under a
mosquito-proof bed net.
4. Use mosquito repellents
when you walk in the woods or other likely
To reduce the risk of malaria, you should begin taking
chloroquine two weeks
prior to departing for regions of the world where malaria is
found. Up to date
information on the status of malaria and drug resistance can
be obtained from
references (1) and (2) below.
No vaccine is currently available against malaria.
Breakthroughs have been made,
but pharmaceutical availability is still many years away.
The most effective drug
against malaria is chloroquine, but in some areas of the
world, the parasite is
beginning to show some resistance to the drug. An
alternative drug that is much
more expensive is sold under the label "Fansidar."
This drug is effective, but can
cause serious allergic reactions in some people. Local
health care providers should
be consulted as to what drug to use.
The search for a vaccine against malaria is complicated by
the fact that while
Plasmodium falciparium is responsible for most malaria
deaths, there are other
plasmodium species, and each species may react differently
to the drugs used to
In addition, the parasite goes through a series of stages of
growth as it passes
from the mosquito into the human bloodstream, back to the
mosquito, and then
back into a human host. Each stage requires its own separate
For example, at one stage of the parasite's life it is
called a gametocyte, a tiny
body that will produce gametes or mature sexual reproduction
cells. The gametocytes
must pass into an anopheles mosquito to develop.
The mosquito bites a person whose blood contains the
gametocytes. The gametocytes
develop in the body of the mosquito and eventually produce
tiny bodies that will grow into adult plasmodia. The infected
mosquito then passes
the sporozoites to another human host and the cycle begins
A vaccine against the sporozoite would keep the second
person from getting the
disease from the mosquito. It would not, however, defend
against, say, contaminated
blood used in a transfusion, nor one of the other infectious
stages of the
The challenge to scientists is to develop vaccines that
would be effective in three
different ways. One would work against the sporozoite,
preventing it from
developing in its human host. Another would work against the
prevent its growth in the body of the mosquito. Both of
these vaccines could
effectively block the transmission of the disease.
They would not, however, protect the person who was infected
as a result of a
blood transfusion. Such a person could become ill with
malaria and would then be
a source of infection to mosquitoes and ultimately to other
people. Thus scientists
are also working on a third type of vaccine, which would
protect against this
type of transmission.
In the meantime, the best protection for people living in
malaria areas is to
interrupt the cycle by getting rid of the mosquitoes or by
trying to keep from
being bitten. Malaria control is a community problem, not
just a challenge to
science. Use the measures described above to eliminate
mosquito breeding areas
around your home, farm, and community. Remember to protect
yourself and your
family from the mosquitoes by using window screens and
mosquito-proof bed nets.
Use mosquito repellents, and spray with appropriate
insecticides where needed.
Dr. Donald Pletsch, VITA Volunteer, Gainsville, Florida
Dr. Alan Greenberg, Center for Disease Control, Atlanta,
"Taking the Bite Out of Malaria," VITA News, January
1986, pp. 4-5.
1. Tropical Disease
Office, Pan American Health Organization (PAHO/WHO), 525
N.W., Washington, D.C. 20037 USA
2. Malaria Division,
U.S. Public Health Service Center for Infectious Diseases,
Meeting the Global Challenge," USAID Science & Technology in
Series. Boston, Massachusetts: Oelgschlager, Gunn & Main Inc.,
4. Viajar con Salud,
Division of Public Information, World Health Organization,
5. Manual on
Environmental Management for Mosquito Control, World Health
1211 Geneva, Switzerland.