M
alaria has caused unimaginable hardship to humanity as
well as loss of millions of human life, from kings to
commoners, from time immemorial.
Many human settlements were decimated, civilizations
declined, wars lost and advance of humanity halted due to
malaria. Until 1897, when the mosquito vector was identified by Ronald
Ross, people tried to protect themselves by various methods
that they deemed fit.
The connection between malaria and swamps was known even in
antiquity and the evil spirits or malaria gods were believed
to live within the marshes.
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Time Line For Malaria
Control |
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Ancient Times |
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Early man attributed the fevers to evil spirits, angered
deities, demons, or the black magic of sorcerers |
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Severel
thousand years ago |
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Babylonian cuneiform script attributes malaria to a god,
pictured as a mosquito-like insect |
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800 BC |
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Indian sage Dhanvantari wrote that bites of mosquitoes could causes
diseases, fever, shivering etc. |
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400 BC |
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Hippocrates attributed malaria to ingestion of stagnant water; also related the fever to the time of
the year and to where the patients lived. |
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100 BC |
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Susruta Samhita
in India associates fevers with the bites of the insects |
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Early
Civilizations |
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Use of mosquito nets recorded; Cleopatra reportedly used
them |
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Early
Civilizations |
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Ancient Romans practiced drainage of swamps to prevent
malaria |
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11 Century
AD |
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Rice
plantation prohibited near human dwellings |
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1717 AD |
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Lancisi linked malaria with poisonous vapours of swamps or stagnant water on the ground
and revived the old idea that mosquitoes might play a role;
proposed the draining of marshes to eradicate malaria |
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Late 1800 |
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Malaria declines in the United States and Europe due mainly
to draining swamps and removing mill ponds; better housing
and beter sanitation |
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1882 AD |
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Albert Freeman Africanus King, a US Physician, proposed to
encircle the city with a wire screen as high as the
Washington Monument as a method to eradicate malaria from
Washington, DC. |
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August 20, 1897 |
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Ronald Ross
demonstrates oocysts in mosquito gut, proving the role of
mosquito in malaria transmission |
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1899 |
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Ross attempted to eradicate malaria from England by forming
‘mosquito brigades’ to eliminate mosquito larvae from
stagnant pools and marshes; organised a sanitation drive at
Freetown, Sierra Leone with limited success |
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1901 |
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William Gorgas of the US Army leads a successful anti
mosquito drive in Havana, Cuba; pyrethrum used for the first
time |
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1902 |
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Ronald Ross
invited to Ismailia by the Suez Canal Company to control
malaria, which he does successfully. |
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1905-1910 |
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Malaria
controlled in Panama Canal site under the leadership of
Ronald Ross and William Gorgas |
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1920 |
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Paris Green first used in malaria control |
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1921-22 |
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Larvivorous
fish Gambusia affinis
or mosquitofish used in the control of mosquitoes in California |
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1939 |
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Malaria
control drive conducted in Brazil under the leadership of
Fred Sopper with great success |
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1955 |
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The Global Malaria Eradication Programme launched by WHO
with emphasis on vector control with DDT residual spraying |
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1965 |
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The Global Malaria Eradication Programme proved successful
in Europe, but cases re-emerge in Asia |
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1969 |
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The Global Malaria Eradication Programme abandoned |
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1998 |
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Roll Back
Malaria Campaign launched |
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The connection between malaria and mosquitoes was suspected from ancient
times. One of the oldest scripts, written several thousand years ago in cuneiform script on clay
tablets, attributed malaria to Nergal, the Babylonian god of destruction and
pestilence, pictured as a double-winged, mosquito-like insect. A few centuries
later, the natives told Philistines settling in Canaan, on the eastern shore
of the Mediterranean, of the god Beelzebub, lord of the insects. The evil reputation
of this deity increased through the ages until the early Jews named him "Prince
of the Devils."
The ancient Hindus were also conscious of the mosquito's harmful potential.
In 800 B.C. the Indian sage Dhanvantari wrote about the diseases caused by bites of the
mosquitoes. Susrutha Samhita
also mentions about
a possible link between fevers and insects like mosquitoes.
Hippocrates, Greek Physician in 400 BC, attributed malaria to ingestion of stagnant water; also related the fever to the time of
the year and to where the patients lived.
Use of mosquito nets has been dated to prehistroic times.
It is said that Cleopatra, Queen of Egypt, also slept under
a mosquito net.
So conscious were the ancient Romans of the association between mosquitoes
and malaria that city officials would routinely prohibit human habitation in
mosquito-infested districts. To protect themselves from the notorious Campagna
mosquitoes, shepherds returning from a summer in the Apennines furnished their
small cabins with a few sheep to satisfy the ravenous insects, thereby hoping to
avoid malaria. The association with stagnant waters (breeding
grounds for Anopheles) led the Romans to begin drainage programs,
the first intervention against malaria. It is said that Emperor
Nero drained the swamps near ancient Rome, in order to rid
the city of malaria. By the Middle Ages, Kings and feudal
lords feared marshes as breeding grounds of plagues and
incurable fevers and a royal decree was passed in 11th century
Valencia, sentencing any farmer to death who planted rice too
close to villages and towns. In
Britain, the
'Roman technology' of draining swamps protected some areas
from malaria during this time.
Italian physician
Lancisi in 1717 had suggested a possible role for mosquitoes in transmission of
malaria and proposed the draining of marshes to eradicate malaria.
Malaria's decline in the United States and
Europe in the late 1800s was due mainly to draining swamps and
removing mill ponds. Draining swamps also exposed good
agricultural land, enabling people to afford better houses and
thus isolate the sick. Increasing livestock densities may have
diverted biting from humans toward cattle, pigs, or horses.
Improved housing, isolation of sick people in mosquito-proof
areas, better access to health care and medication, and improved
nutrition, sanitation, and hygiene all may have reduced
transmission and/or mortality rates.
In 1882, Albert Freeman Africanus King (1841-1915), a US Physician, proposed
a method to eradicate malaria from Washington, DC. He suggested to encircle the
city with a wire screen as high as the Washington Monument. Although many people
took this as a jest, his hypothesis to link mosquitoes with malaria transmission
was proved five years later.
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Major Ronald Ross |
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Ronald Ross's discovery of Anopheles mosquito as the
vector for malaria in 1897 opened
a new chapter in malaria control. With his brilliant research,
he not only identified the habits and habitats of these mosquitoes
but also proposed detailed plan of action to contain their
breeding. Ronald Ross did not stop at writing about malaria
control either. He stood at the vanguard of implementing his ideas
till his end. Ross attempted to eradicate malaria from England
by forming ‘mosquito brigades’ to eliminate mosquito larvae
from stagnant pools and marshes. In 1899, he was sent to Freetown,
the capital of Sierra Leone where he organised a sanitation
drive, clearing the streets of tyres, bottles and empty cans
and levelling roads so that rain water would not gather
into puddles. But the Freetown malaria control
programme did not yield desired results, probably because Ross had
underestimated the number of breeding pools and the sheer number of vectors
that he was
trying to control. Ross had very limited funding and the best available technology
was to pour
oil on the numerous breeding sites around Freetown. As soon as the oil treatments stopped, breeding
would begin
again. Ross redoubled his efforts with increased funding from private sources
and ensured the
removal of all potential breeding sites, including rubbish, broken bottles and
other potential
water containers. Despite these concerted efforts, the programme was remembered
more for
its impact on the Freetowns rubbish than with malaria control. J.W.W. Stephens and S.R. Christophers, who had worked
with Ronald Ross in Freetown, organised a similar drive in Mian
Mir in Lahore, India in 1901, without much success.
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GB Grassi |
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Italian physician Giovanni Battista Grassi, who demonstrated transmission of
malaria from mosquitoes in man, did his own bit in controlling malaria. He warned against taking walks in
the twilight, the prime mosquito feeding time. "Don't go out in the warm
evenings," he announced, "unless you wear heavy cotton gloves and
veils." Naturally he was laughed at. To prove his point, Grassi set up an experiment to prevent malaria in the most
heavily diseased region in Italy, the railroad line that ran through the plain
of Capaccio. With funds from the queen of Italy and authority from the railroad,
Grassi installed fine mesh screens on the doors and windows of ten stationmasters'
houses. One hundred twelve employees were paid to stay inside during the twilight.
Another four hundred fifteen workers went out as usual. At the end of the summer,
almost all the unprotected developed malaria. But of the hundred and twelve
protected individuals, only five got sick. "In the so much feared station of Albanella," wrote Grassi triumphantly,
"from which for years so many coffins had been carried, one could live
as healthily as in the healthiest spot in Italy!"
During the
same period, Watson organised draining the salt marshes on the parts of
the west coast of Malaya so as to make it habitable.
The sanitation drive suggested by Ronald Ross was
successfully tried elsewhere. During
the U.S. military occupation of Cuba, a campaign against
yellow fever and malaria was commenced at Havana early in 1901. Under the
leadership of
the
Assistant Surgeon General William Gorgas of the United States Army the anti
mosquito measures produced very marked results. Pyrethrum,
a natural
insecticide derived from the chrysanthemum flower, was first
used by William Gorgas in Cuba where it was burned inside sealed dwellings. Mosquitoes
entirely disappeared from many parts of the city, and were
decreased everywhere.
At the end of 1902, Prince Auguste d'Arenberg, President of the Suez Canal Company asked
Ross to save Ismailia, the city that was built as a base for construction of the
canal. It was gravely threatened by malaria for a long time. Ross led a
sanitation drive so successful that by the following year, the city officials
announced that they no longer needed mosquito nets and by 1904, a whole year had
passed without a single reported case of malaria in Ismailia. Ross's drastic
sanitary measures were even dubbed as "sanitary Bolshevism".
Ross conducted similar campaigns in Greece, Mauritius, Spain
and during World War I at various places on the battle front.
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William Gorgas |
The experience of the US Army in Cuba was replicated during the construction of the Panama Canal
between 1905-1910. The
construction was made possible only
after yellow fever and malaria, major causes of death and disease
among workers in the area, were controlled. During the French
reign between 1882 and 1888, an estimated 10000-20000 workers
had died at the canal zone owing to these diseases. Therefore,
before the construction could begin, Gorgas surveyed the area. Ronald Ross and William Crawford Gorgas
worked together to eradicate malaria from Panama. In 1906, there were over 26,000 employees
working on the Canal. Of these, over 21,000 were hospitalized
for malaria at some time during their work. By 1912, there were
over 50,000 employees, and the number of hospitalized workers
had decreased to approximately 5,600. Through the leadership and
efforts of William Crawford Gorgas, Joseph Augustin LePrince,
and Samuel Taylor Darling, yellow fever was eliminated and
malaria incidence markedly reduced through an integrated program
of insect and malaria control. Drainage, brush
and grass cutting, oiling and larviciding (when oiling
was not sufficient) were all done. At the time, there were
no commercial insecticides. Joseph Augustin LePrince, Chief
Sanitary Inspector for the Canal Zone developed a larvacide
mixture of carbolic acid, resin and caustic soda that was
spread in great quantity. In addition, quinine was provided
freely to all workers. Screening was provided to dwellings and
attempts were made to kill the adult mosquitoes. Because the
mosquitoes usually stayed in the tent or the house after
feeding, collectors were hired to gather the adult mosquitoes
that remained in the houses during the daytime.
In 1916, Dr. A.R. Campbell, a
Bacteriologist at San Antonio, Texas constructed a bat house
to colonize bats in order to destroy the malaria carrying
mosquitoes. [See]
The best method of malaria control was a topic of hot debate
during this period. Battista Grassi, Italian parasitologist,
suggested tighter netting. The renowned German microbiologist
Robert Koch thought is possible to eradicate malaria by giving
quinine as a prophylactic ("cinchonisation"). Ross
did not agree with these views. SP James suggested that malaria
will only disappear with improvements in housing and the separation
of mosquitoes from humans. Thus malaria was considered to
be a social disease and the remedy was to improve the economic
life of the subjugated populations by good housing, good nutrition,
good health and education services coupled with modern agricultural
practices. Economic betterment was advanced as the cause of
the disappearance of malaria from northern Europe and England
- where more than 10,000 cases had been admitted to London's
St. Thomas's Hospital alone between 1860 and 1870, followed
by a rapid decline to four or five cases each year by 1925.
Malcolm Watson and LW Hackett of England and the Americans
Fred Soper (See below) and Paul Russell supported Ronald Ross's emphasis
on vector control. There was also another view that nothing
should be done so as to allow immunity to develop, even at
the cost of a few young lives. Until 1944, when pesticide
DDT was rediscovered as a new weapon against mosquito control,
only quinine and insecticides pyrethrum and Paris green were
available to help in malaria control efforts.
See Below: Insecticides in mosquito
control
Paris
Green (a mixture of diesel oil and copper acetoarsenite) was first used in malaria control in the 1920s in many countries like
India, South Africa and Brazil.
In 1921-22, a
fish called Gambusia affinis
or mosquitofish was
the released into water collections for its larvivorous habits
and was found useful in the control of mosquitoes in California.
In 1933 Tennessee River valley authority and the Public
Health Service played a vital role in the control
operations of malaria in the area and by 1947, the disease was essentially
eliminated. Mosquito breeding sites were reduced by
controlling water levels and insecticide applications.
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Fred Soper |
Another great success story in malaria control during this
period was in Brazil. And the man who campaigned vigorously for
the eradication of the mosquito from this part of the world was
an unusual American named Fred Soper, who was born in Kansas in 1893 and was educated at Johns Hopkins School of Public Health.
He was a man of legendary energy endowed with great common sense. When thousands of larvae of the malarial mosquito
A. gambiae were discovered in 1930 along a river in Brazil,
thousands of miles from their homeland in Africa, Soper recommended opening the dykes damming the tidal flats,
given that salt water destroys the breeding areas. But the Government refused, and malaria began to spread infecting
100,000 people, and killing 20,000 in 1938. The Brazilian President, Getulio Vargas enlisted the services of Soper
to eradicate the mosquito – a kind of ‘mission impossible’ and
in 1939, the Malaria Service of Northeast Brazil was organized to combat the populations of
Anopheles gambiae. Soper and his team of 40,000 workers fumigated houses
and buildings with Pyrethrum and sprayed Paris Green on pools of water. In just 22 months, he was able to
eradicate the mosquito from an area of about 18,000 square miles in Brazil. Fred Soper’s
success was considered a great public health achievement in
Brazil, and he was rewarded with medals and citations. This
effort at species eradication was so successful that the
mosquito is still absent from the area. This was before DDT
was used in anti-malaria programmes.
The Centers for Disease Control (CDC) was organized in
Atlanta, Georgia, on July 1, 1946. Office of Malaria Control
in War Areas, an agency established in 1942 to limit the
impact of malaria and other vector borne diseases (such as murine
typhus) in the southeastern US during World War II was the
predecessor of CDC. Dr. Justin M. Andrews, director of CDC
from 1947 to 1951, was also the state malariologist for the
state of Georgia. In the ensuing years, CDC oversaw the US
national malaria eradication program and provided technical
support to activities in the 13 states where malaria was still
endemic. By 1951, malaria was
considered eradicated from the United States. However, to the
present day, malaria remains a major field of activities at CDC.
Up to 1950s, malaria control programmes in many countries
involved treatment with quinine, personal protection with
bednets and anti larval measures that included drainage, soil modification, proscription
of urban
agriculture (potatoes and other ridge-and-furrow type cultivation).
The efforts were most often concentrated in urban areas. Some
countries passed very strict, even draconian, legislations
like the Mosquito Extermination Act for ensuring source
reduction. These required all householders to prevent
mosquito breeding sites by clearing all vegetation surrounding
the house to a distance of ten metres in all directions. Any
container that could possibly hold water and therefore provide
a breeding site was to be removed from the household area.
Regular inspections were made by the government health department
in order to ensure that all households were complying with
the legislation. Those households that did not comply were
either subjected to a fine or the head of the household could
be imprisoned. Such acts also required all
mines, quarries, irrigation, water supply and other works
to take specific measures to ensure that mosquito breeding sites
were destroyed. With the availability of DDT in 1943, adult
insecticidal operations were initiated by spraying and misting with adulticidal devices
in tents and buildings, and by release from aircraft. By
1934-49, malaria was eradicated from Brazil and Egypt, largely
due to extensive DDT spraying.
The WHO took up malaria eradication programme in 1955. In 1953, Brazilian malariologist
Marcolino Candau, who campaigned on the promise of malaria
eradication won the elections to the post of the director
general of WHO defeating the psychiatrist Brock Chisholm.
The Global Malaria Eradication Programme was launched in 1955
emphasising on vector control with DDT residual spraying and
surveillance in all national programmes. The goal was to reduce infected vector
populations feeding on humans sufficiently to interrupt
parasite transmission. The programme imposed
an uniform strategy for all countries and areas, ignoring
the diversity of malaria and economy of nations, particularly
the new governments
then emerging from colonial rule. Sub-Saharan Africa was not
included (or even ignored) due to its massive reservoir
of malaria and insufficient
infrastructure to support the programme. However, malaria
was eradicated in nations with temperate climates and seasonal
malaria transmission. The last indigenous case in
England had been in the 1950s and in Holland
in 1961. By 1969, many European countries namely Hungary,
Bulgaria, Romania, Yugoslavia, Spain, Poland, Italy, Netherlands
and Portugal managed to completely eradicate their
endemic malaria. (In 1975, the World Health
Organization declared that Europe was free of malaria).
Some countries such as India and Sri Lanka had sharp
reductions in the number of cases, followed by increases to
substantial levels after efforts ceased. Other nations had
negligible progress (such as Indonesia, Afghanistan, Haiti,
and Nicaragua). Despite initial success in countries like
India, by 1965, it started falling apart due to a number of
factors: technical difficulties such as vector and parasite
drug resistance, social and political factors preventing
efficient application of control measures, wars and massive
population movements, difficulties in obtaining sustained
funding from donor countries, and lack of community
participation that made the long-term maintenance of the
effort untenable. The programme was criticized for being too inflexible
like a military operation and received little support or even
opposition from the local populations. By 1969 WHO admitted
the failure of this campaign and the global eradication policy
was abandoned. Several years later, the WHO’s Malaria
Eradication Division changed its name to the Division of
Malaria and Other Parasitic Diseases.
Between 1969-1976, the World
Health Organisation co-ordinated an intensive study of malaria
in the Garki district of Northern Nigeria. Many problems that
could have a bearing on malaria control, like high bite
intensity, high proportion of vectors carrying the parasite,
mosquitoes resting outdoors after blood meals instead of
indoors on insecticide treated walls, were revealed by this
study. It was concluded that the use of drugs and insecticides
could markedly reduce the incidence of malaria in the short
term but was not enough to break transmission and achieve
long-term success.
From the early 1970's the malaria situation has slowly and
progressively deteriorated. The
concept of eradication was replaced with that of control as
a part of primary health care. Reduced control measures
between 1972 and 1976 due to financial constraints lead to
a massive 2-3 fold increase in cases globally. Spraying never
truly eradicated the mosquitoes anywhere, and the reduction
in the more persistent P.vivax infections were much
less than for P.falciparum - though the latter returned
in much greater strength as control measures waned. The growing
interchange of populations between malarious countries and
malaria free countries is responsible for the continuous increase in the number
of imported malaria cases in developed countries. Since 1976, several new
pockets of malaria transmission have evolved.
Malaria
control in the 1980s was neglected in many areas. The optimism
of the eradication campaign was replaced by a belief that
malaria could not be controlled. The systems set up for eradication,
which were very centrally organised and directed were discredited,
and support was withheld without offering alternative systems
and strategies. Whilst it was said that malaria control should
be integrated into the general health systems, instead of
being a vertical programme, the means to do this were neglected.
At the end of the 1980s and in the early 1990s the World Health
Organisation (WHO) worked with all malarious countries to
develop a global strategy for malaria control. This strategy
was adopted by a Global Ministerial Conference on Malaria
in Amsterdam in 1992. The strategy has four elements:
-
To provide early diagnosis and prompt treatment
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To plan and implement selective and sustainable preventive
measures, including vector control
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To detect early, contain or prevent epidemics
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To strengthen local capacities in basic and applied research.
The strategy was widely endorsed, and efforts to implement it
have shaped the development of malaria control in most malarious
countries. It has been adapted to the needs of different
regions; in Africa, for instance, a Regional Malaria Control
Strategy for 1996 to 2001 was developed by a Task Force for
Malaria Control convened by the WHO African Regional Office
(AFRO).
In 1998 Dr. Gro Harlem Brundtland, Director
General, World Health Organization launched a Global Roll Back
Malaria Initiative against malaria. The RBM Strategy included
Early case detection and prompt treatment, Integrated vector
management and
Containment of focal epidemics. However, the programme is far from
being successful.
Today, it's a much worse scenario. Thoughtless man-made
irrigation schemes and dams provided new habitats for
Anopheles, and resulted in 'man-made' malaria. The extension
of urban areas lead to epidemics in the peripheries of the
growing cities. Mass migrations of non-immune populations into
endemic areas for political reasons has further complicated
matters. More than 300 million cases with 2
million deaths, multi-insecticide and multi-drug resistance, non-use of DDT, non-availability of cheap and effective chemo-therapeutics
and prophylactics, steady-state, benign holoendemic
malaria replaced by unstable hyperendemicity, functional immunity impaired by the ad hoc chemotherapy
distributed from the primary health centres - It is déjà vu
all over again. New technology promises to bring the
always-in-the-pipeline vaccine and the more flashy bed nets dipped in permethrin. The super-sensitive, single-minded Ross went to his grave
still holding the firm conviction that malaria could be eradicated
if only weak-willed governments would commit themselves to
exploit his discovery and attack the anopheline in their watery
lairs.
Use of Insecticides: As early as 1825 Michael
Faraday reported to the Royal Society of London the formation
of benzene hexachloride. However, it had to wait for more than
115 years to become useful as a pesticide. Similarly, Dichlorodiphenyltrichloroethane (DDT) was first
synthesized in 1874 by a Viennese pharmacist, Othmar Zeidler,
but he did not investigate the properties of the new
substance. The use of chemicals to control troublesome
insects so as to save food crops started by mid 19th century.
Paris
green was used as an insecticide in 1867. Production of pyrethrum,
which is a natural insecticide derived from the chrysanthemum
flower, started in the US by 1870.
In 1882, Petroleum was first recommended in the US for insect
bites and stings. By 1897 oil of
citronella was used as insect repellent. Pyrethrum was first
used by William Gorgas in Cuba where it was burned inside sealed dwellings.
In around 1910, the German scientist G. Giemsa was experimenting with different
ways of
using pyrethrum and developed a way of spraying pyrethrum on walls with a spray
pump.
This method took over two decades to catch on, and it was used with great success
in South Africa for the control of malaria on sugar estates. In 1920 Oil-soaked
sawdust was first recommended for mosquito control and Paris
green was considered as the a mosquito larvicide. Paris
Green was first used in malaria control in the 1920s. It was used in countries
like India, South Africa and Brazil.
In 1924, Paris
green dust was applied to swamps in Louisiana for control of
Anopheles mosquitoes. In 1942, many chemicals were
tested for
control of insect-borne disease among Armed Forces. By 1947,
more than 13,000 such chemicals had been tested and
classified, but the glory went to DDT, resynthesised by Paul
Muller in 1939 [See below] In 1943,
Van Linden gave the name lindane to the
pesticide made with the active isomers of the benzene hexachloride
mixture.
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Paul Müller |
Although
DDT was first synthesized in 1874 by a Viennese pharmacist, Othmar Zeidler,
he did not investigate the properties
of the new substance but simply published his synthesis. Then
in 1939 in Switzerland, Paul Müller of the Geigy Company, resynthesized
this compound and discovered its insecticidal properties. The Geigy
Company began to market the substance in 1940-41 as a 5% dust called Gesarol spray insecticide and
a 3% dust called Neocid dust insecticide. The now
universally used name, DDT, was first applied by the British
Ministry of Supply in 1943. DDT was first added
to U.S. Army supply lists in May 1943. Gahan
and colleagues, in August 1943, made the first
practical tests of DDT as a residual insecticide against adult
vector mosquitoes. The first field test in which residual DDT was applied to
the interior surfaces of all habitations and outbuildings
of a community to test its effect on Anopheles vectors
and malaria incidence was begun in Italy in the spring of
1944. This experiment was carried out in the town of Castel
Volturno at the mouth of the Volturno River, north of Naples,
by the Malaria Control Demonstration Unit of the Malaria Control
Branch of the Public Health Sub-Commission, Allied Control
Commission, Italy. Spraying began on 17 May 1944, and this
experiment, together with a second one started later in the
Tiber Delta area, lasted 2 years. The war needs and experiments greatly accelerated its
acceptance and use and led to the discovery and application
of similar insecticides such as benzene hexachloride and dieldrin.
However, by 1949
mosquitoes resistant to DDT and other new insecticides were
found. In 1962, Rachel Carson published Silent Spring. In it, she
discussed the decline in certain regions of the United States of
the America robin, due to its consumption of earthworms that
were laden with the DDT used in massive amounts to combat Dutch
elm disease. Carson's book stimulated widespread public concern
about DDT and other pesticides. Through a series of legal
hearings in the United States instigated by lawyers and
scientists working with the Environmental Defense Fund, DDT was
eventually banned or severely restricted in most states. In
1972, the U.S. Environmental Protection Agency banned all DDT
uses except those essential to public health. Similar bans were
instituted by Sweden in 1969 and later in most of the
developed countries. But DDT is still being used in some developing
countries to control malaria, but the debate is continuing.
Sources:
Also See
History of
Origin of Malaria
Parasite And Its Spread
History of Malaria During
Wars and Upheavals
History of Malaria And Its
Famous Victims
Malaria In
Ancient
Literature
History of
Scientific Discoveries on Malaria
History of
Anti
Malaria treatment
History of Malaria
And Its Control In India |