The biological basis for the campaign against the malaria vectors of Brazil

663 TRANSACTIONS OF THE ROYAL SOCIETY OF TROPICAL MEDICINE AND HYGIENE.

Vol. 44. No. 6. June, 1951.

THE BIOLOGICAL BASIS FOR THE CAMPAIGN AGAINST THE MALARIA VECTORS OF BRAZIL. BY

M/kRIO PINOTTI, Director of the National Malaria Service of Brazil.

Until quite recently malaria was considered to be one of the two or three principal public health problems of my country. It may sound strange to use the word " was " rather than " is," when speaking of malaria. M y justification, however, lies in the fact that during the last few years this disease has been brought under control in the major part of this country, and it should therefore before long cease to be a serious obstacle to the advancement of the Brazilian nation. We can visualize in the near future the almost complete control of malaria, as has already occurred with yellow fever which has practically disappeared from this country as a result of the laudable efforts of the Rockefeller Foundation and of the Brazilian Yellow Fever Service. At the present time the existence of yellow fever is only recognized in occasional outbreaks of the sylvan form of that disease. The object of this paper is to show that the methods employed by the National Malaria Service to combat malaria throughout Brazil are based upon the biological characteristics of the vector species. Brazil has an area of 8,500,000 square kilometres, being subdivided into 1,780 municfpios. Malaria has been found in more than 60 per cent. of those municipios, which indicates the very wide dissemination of the disease. In the greater portion of this country malaria is present in endemic form while in a few zones occasional epidemics appear. The highest endemic indices have been found in the valleys of the Amazon and S~o Francisco rivers and in certain regions of the coastal lowlands. Northern Paraml is one of the epidemic regions. The State of Rio Grande do Sul is largely free of malaria with the exception of two coastal municfpios where the disease exists in mild endemic form. Like-

664

MALARIAL V E C T O R S OF B R A Z I L

wise the semi-arid regions of the north-east, which include a large part of the States of Cearfi, Rio Grande do Norte, ParMba, Pernambuco and northern Bahia are practically free of malaria. In addition, malaria is absent from certain portions of the interior of Minas Gerais, from parts of the valley of the ParMba river in the States of S~o Paulo and Rio de Janeiro, and from the central zone of Santa Catarina. While in certain regions of Brazil transmission takes place at all times of the year, in most of this country the natural spread of the disease is interrupted during certain months. Seasonal variations in the incidence of malaria are dependent upon rainfall. About 50 species of Anopheles have already been identified in Brazil but only nine of them have been found naturally infected. They are the following: (1) (2) (3) (4) (5)

Anopheles (Nyssorhynchus) darlingi. A. (N.) aquasalis (=A. tarsimaculatus). A. (N.) albitarsis. A. (N.) strodei. A. (N.) noroestensis.

(6) (7) (8) (9)

A. A. A. A.

(N.) pe~soai. (Kerteszia) cruzii. (1<2.)bellator. (1<2.)homunculus (?)

Among those nine species only five are really responsible for the major portion of the malaria transmitted in Brazil. These are A. darlingi, A. aquasalis, A. albitarsis, A. cruzii and A. bellator. The other four species have been found infected on one occasion each and they are therefore considered to be of little or no epidemiological importance. From the point of view of the vectors we may subdivide the problem in Brazil into the Nyssorhynchus and the Kerteszia problems. The 25th parallel of south latitude forms the geographical dividing line between those two zones, the subgenus Nyssorhynchus being responsible for endemic malaria north of that line and the subgenus Kerteszia south of that latitude. The area of Nyssorhynchus malaria takes in most of Brazil and is a national affair, whereas the Kerteszia zone is restricted to a region of some 40,000 square kilometres in area. Though the former is milch more extensive than the latter, in both reg'ons endem:c malaria is a serious matter. The Nyssorhynchus problem may also be subdivided into an interior and a coastal one, Anopheles darlingi being the vector responsible for the former and A. aquasalis for the latter. Unfortunately this subdivision is not applicable everywhere, because there are certain coastal zones where A. darlingi and A. aquasalis are both present and other areas where A. albitarsis, in addition, enters the picture. Coastal malaria transmission, therefore, may be ascribed to any one of three possible combinations of vectors : (a) A. aquasalis + A. darlingi.

(b) A. aquasalis + d. albitarsis. (c) A. aquasalis + A. albitarsis + A. darlingi.

When it is realized that these three important species of Nyssorhynchus are ecologically distinct, the complexity of our control problem becomes evident.

MARIO PINOTTI

665

Transmission in the interior is a relatively simple matter, because if we disregard the three doubtful vectors--A, strodei, A. noroestensis and A. pessoai--the only malaria vector of real importance is A. darlingi. An exception to this statement has been found in the north-east, where A. aquasalis has been taken as far as 250 kilometres from the sea coast in a region in which the salinity of the soil is unusually great. (LuCENA, 1946). A. darlingi is absent from that restricted area and the severe epidemics which have occurred there may be ascribed to A. aquasalis. Indeed, in the north-eastern states of Brazil A. darlingi has only been reported from the vicinity of where the S~o Francisco river flows into the sea. The Kerteszia problem, although mainly produced by two species, A. cruzii and A. bellator, may be considered as a unit because both species are biologically similar. If, however, we wish to subdivide them in any way they may be separated on a phytogeographic basis. A. cruzii predominates in the heavily forested regions while A. bellator prefers the more open and sunny coastal zone. There is, however, no sharp subdivision between the two because in certain areas of high A. bellator density, A. cruzii also is found in abundance. The Kerteszia problem is one of the most interesting ones confronting the Brazilian malariologist because of the unusual type of breeding places preferred by these mosquitoes. Eight species are included in the subgenus Kerteszia, seven of which pass their larval stage in the water that collects at the leaf bases of plants belonging to the family of the Bromeliaceae. The eighth, which was given the name A. bambusicolus by KOMP (1937), was found breeding in the unbroken joints of a large bamboo. With the exception of the latter the larvae of all kerteszias are found in bromeliads, which justifies the use of the term " bromeliad malaria " to describe this entity. Only two regions are known in the world where bromeliad malaria is an important proble m. One of them is on the island of Trinidad and the other lies in the south of Brazil. REY (1947)reported the finding of one infected specimen of: A. (Kerteszia) neivai among 3,000 dissections made at Potedo, Colombia. This isolated finding does not appear go indicate that bromeliad malaria is a serious problem in that country. In the region of Trinidad, where A. bellator is the only vector, bromeliad malaria is essentially rural and confined to the area of the principal cocoa plantations. A zone of some 200 square kilometres is involved, whereas in south Brazil the affected region extends along the sea coast from 25 ° to 29 ° 30' south latitude and it covers about 40,000 square kilometres. In Brazil several important cities lie in the zone of bromeliad malaria so that we have an urban as well as a rural problem which affects a population of nearly 1,000,000 people. Bromeiiad malaria has been found on the coast of S~o Paulo, Paranfi, Santa Catarina and in the northern part of Rio Grande do Sul. The area on the Serra de Cubat~o near S~o Paulo, where an epidemic of bromeliad malaria occurred many years ago, is no longer considered to be part of the endemic region.

666

MALARIAL VECTORS OF BRAZIL BIOLOGICAL CHARACTERISTICS OF THE VECTOR SPECIES.

Anopheles (N.) darlingi. Of all the species of Anopheles encountered in Brazil A. darlingi has the worst reputation, so much so that it has often been stated: " Wherever A. darlingi is found there malaria likewise is present." This species is responsible for the endemic malaria of the far interior and it is the principal vector in this country. It transmits that disease in the valleys of the major rivers and in the vicinity of many impounded reservoirs. Its preferential breeding places are large, deep, shaded reservoirs containing cool water and floating plants such as Pistia a~d Eichornia. Large aggregations of these plants in the form of floating islands facilitate the passive dissemination of A. darlingi particularly during times of flood.

•

°

•

•

°

MAP 1 . - - C o u n t i e s (municipalities) i n Brazil e x a m i n e d p r i o r to 31st D e c e m b e r , 1949, in w h i c h Anopheles (N.) darlingi have b e e n f o u n d •

5~ARIO PINOTTI

667

This is the most domestic anopheline in Brazil. It enters houses at night in search of a blood meal and rests, after feeding, on the lower part of the walls. In certain regions such as the S~o Francisco river valley, it is at times captured in considerable numbers with animal bait (BUSTAMANTE, LAI2ERDA, PARACAMPOS and SANTOS, 1949). Generally, however, the number of specimens caught inside houses is much larger than the number taken with a horse as bait. It is very susceptible to infection with human plasmodia, and the natural infection rate is high. A. darlingi is widely distributed in Brazil, showing marked variations in seasonal prevalence as well as long-term fluctuations in its abundance, which extend over periods of 5 years or more. Certain biological attributes of A. darlingi are of great epidemiological interest. In the Valleys of the Amazon and SAo Francisco rivers endemic malaria transmitted by A. darlingi is perennial. Some regions of SAo Paulo and Paran5 on the other hand are characterized by malaria epidemics, which are associated with an excessive production of A. darlingi and which appear every 5, 6 or 7 years. During inter-epidemic periods adults of that species disappear completely, though it has usually been assumed that larval production must have continued in certain isolated places, from which reservoir foci new generations develop and reinvade the entire region whenever meteorological conditions again become favourable.

Anopheles (N. ) aquasalis ~- ( A. tarsimaculatus). This is the dominant coastal vector of malaria in Brazil, being absent only from the three southernmost states. Its principal biological requirement is an appreciable amount of sodium chloride in its breeding places. Its area of distribution is restricted to a narrow band of territory along the sea coast except for certain zones in the interior of the north-eastern states, where a high salt content is present in the ground water. One such region has been found in Pernambuco (LuCENA, 1946) and another in Cearfi (RACHOU, LIMA and LIMA, 1950). Records from the former indicate that A. aquasalis is present 250 kilometres from the sea coast at an elevation of 750 metres above sea level. The preferred breeding places of A. aquasalis have a salt content ranging from 2 to 10 g. per litre, although larvae have once been found in a breeding place containing as much as 33 g. of salt per litre (LuCENA, 1946). The most prolific breeding areas are those which are exposed to direct sunlight. Adults of A. aquasalis are often produced in enormous numbers with the result that its importance as a vector depends more upon this excess than upon any pronounced preference for human blood. In certain zones of the northeastern states, howe,cer, A. aquasalis has become a domestic insect. Throughout the remainder of its territory this species attacks man or animal with equal ferocity, invading houses or stables for that purpose. During the principal breeding season well-fed adults may be captured in the daytime resting inside

668

MALARIAL V E C T O R S O F B R A Z I L

\ \

j

/

MAP 2.--Counties (municipalities) in Brazil examined prior to 31st December, 1949, in which Anopheles (N.) aquasalis have been found. human habitations, but more frequently they enter houses during the night and depart at dawn. When adults are found resting inside dwellings they are generalIy taken near the floor. Naturally infected specimens have been captured both inside houses and with human bait out in the open. Anopheles (N.) albitarsis.

Among the three vector species of Nyssorhynchus, A . albitarsis has the widest geographical distribution and the least importance in the transmission of the disease. It varies greatly in its density, its habits, and to some extent also in its morphology. Five subspecies have been described: (1) A. albitarsis albitarsis. (4) A. albitarsis domesticus. (2) A. albitarsis brasiliensis. (5) A. albitarsis imperfectus. (3) A. albitarsis limai.

MARIO PINOTTI

669

The variety which has been found naturally infected with malaria is A. albitarsis domesticus. This subspecies shows a marked preference for human blood and it is characterized by having the second hind tarsal segment nearly half black. After a blood meal in a human dwelling, adults often rest on the upper part of the wall. Infected specimens have been taken only near the sea coast, while the varieties of A. albitarsis which have been captured in the interior are probably of no epidemiological importance• In some coastal areas naturally infected specimens of both A. aquasalis and A. albitarsis have been found, while in two limited zones in the States of Bahia and SRo Paulo A. albitarsis domesticus is reported to be the only vector present Larvae of A. albitarsis have been secured in a great many different types of habitat.

•, .

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•

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.

MAP 3.--Counties (municipalities) in Brazil examined prior to 31st December, 1949, in which Anopheles (N.) albitarsis have been found.

670

MALARIAL VECTORS OF BRAZIL

Anopheles (N.) strodei. This abundant species has a wide distribution in Brazil but is rarely found in human habitations and it has been found naturally infected on only one occasion in the State of S~o Paulo (CORREA, 1939). A. strodei feeds on animals by preference and is not considered to be an important vector in this country.

Anopheles (N. ) noroestensis. This is a widely distributed zoophilic species, which has only once been found infected in nature (CoRREA and RAMOS, 1941).

Anopheles (N.) pessoai. A single infected specimen of A. pessoai was captured in the Amazon valley (DEANE, CAUSEY and DEANE, 1948) some years ago but this finding is of little or no significance as this species is a rare one and has a very limited distribution in Brazil.

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MAP 4.--Counties (municipalities) in Brazil examined prior to 31st December, 1949, in which Anopheles (K.) cruzii have been found.

MARIO PINOTTI

671

The subgenus Kerteszia. Among the three vector species belonging to this subgenus--A, cruzii, A. bellator and A. homuneulus--we consider the last to be of doubtful importance. In Blumenau (Santa Catarina) A. homunculus is much more abundant than A. cruzii but it can only be distinguished from the latter by the male terminalia. Although infected specimens were encountered in Blumenau, their exact identification was never ascertained because no ovipositions were secured from them from which males could have been bred and accurately identified. For that reason the incrimination of A. homunculus is not yet an established fact. The two other members of the subgenus Kerteszia are the only proved vectors of malaria (RACHOU, 1946) in the endemic area which extends along the coast of the three southern states. In this region we have often taken from 100 to 300 adults per man-hour during day or night-time captures. These mosquitoes will bite voraciously at all times not only inside houses but also .out in the open. Both A. bellator and A. cruzii are strikingly antropophylic. The domesticity of the kerteszias of south Brazil is an epidemiological characteristic that distinguishes them at once from the kerteszias of Trinidad. Throughout our region of bromeliad malaria from 90 to 100 per cent. of the adults that are caught inside houses are kerteszias. For instance, during the 2-year period from 1944 to 1945, out of a total of 20,159 anophelines captured in houses in certain of our study areas 99.5 per cent. belonged to the subgenus KertesMa. At Caldas da Imperatriz 1 year of work yielded 63,632 adult anophelines, almost all of them being A. cruzii. In many other small settlements adult kerteszias have been found in one out of every four houses examined. Although kerteszias invade houses at all times of the day, their period of greatest activity runs from midnight to dawn. After feeding they prefer to rest on the ceiling or on the higher parts of the walls. Naturally infected specimens of A. cruzii and A. bellator have been secured in various places in Paran~i and Santa Catarina. Most of those infected mosquitoes were obtained inside houses but a few were caught in the open with human bait. Malaria transmission in this region therefore may be either an intra- or :an extra-domiciliar phenomenon. CAMPAIGN AGAINST THE VECTOR SPECIES.

The National Malaria Service of Brazil, which I have had the honour to direct since the end of 1942, was created in 1941. Previously there had been no special federal department responsible for all malaria control activities throughout the length and breadth of this land. It is only fair to call attention at this point to the striking victory achieved by the Brazilian Government, :assisted by the Rockefeller Foundation, in the eradication of A. (/1//.) gambiae from the north-east of this country, where it had been introduced from West Africa (SOPER and WILSOI% 1943). As this notable achievement is now well known, I will not elaborate it any further.

672

MALARIALVECTORS OF BRAZIL

In the beginning the Nationat Malaria Service limited its activities to the environs of the State capitals and to a few of the other important cities as well as to military bases. During that epoch Brazil entered the war, which necessitated careful attention to all military installations, particularly those situated along the Atlantic seaboard. For some years it was necessary, therefore, to devote a major part of our modest budget to the care of those important bases, which we feel confident had its value in helping to bring the war to a successful conclusion. During the early years of its existence the National Malaria Service dedicated most of its efforts to larval control. Paris green, oil and minor drainage were relied upon to hold Anopheles production in check. Later, with the advent of insecticides of prolonged residuaI toxic action, we began to realize the possibility of extending our field of action to all the malarious regions of Brazil. Our campaign, therefore, falls naturally into two periods :

/

MAP 5.--Counties (municipalities) in Brazil examined prior to 31st December, 1949, in which 21nopheles (K.) bellator have been found.

M A R I O PINOTTI

673

(1) By means of household spraying with D D T we have attempted to cover all of the malarious areas of this country in order to reduce malaria from its pre-eminefit position to one of secondary importance in the national sphere. (2) Eradication of malaria from Brazil. From the previous exposition of the biological characteristics of our vector anophclines, it is evident that our nation-wide campaign of house spraying is founded on a rational basis. A. darlingi and A. albitarsis domesticus are essentially domestic mosquitoes, while A. aquasalis, A. cruzii and A. bellator are also frequently attracted to houses, though not invariably so. House spraying with D D T therefore gives excellent results in areas where A. darlingi or A. albitarsis domesticus predominate, and this measure ought to be of distinct utility on those regions where the other three vectors are found. An insecticide with a long lasting residual action, while not an offensive weapon which could bring about the complete disappearance of any one of our Brazilian vectors, is certainly an excellent defensive arm with which to prevent the continued transmission of the disease among the human population. By the intra-domiciliar application of DDT, aided by an abundant supply of suitable antimalarial drugs, we hope to be able to reduce malaria transmission to a point where it will no longer be a serious obstacle to the advancement of this nation. Once that objective has been achieved we shall then be in a position to attempt the actual eradication of malaria from this country. Until the appearance of an infallible therapeutic agent the only means at our disposal has involved the limited eradication of the vector mosquitoes. This has actually been achieved in certain small circumscribed areas but it appears to be rather a Utopian project for an area 8,500,000 square kilometres in size. Nevertheless, the greater the difficulties and obstacles that will have to be overcome, the more attractive looms the prospect for the National Malaria Service of Brazil to make an attempt to undertake this bold enterprise. For that very reason a malaria institute has been created where both nationals and foreigners are attacking the stil! unsolved problems connected with the final control of that disease in this country. Our nation-wide programme of house spraying with D D T will be completed by the end of 1950, • with the exception of the States of Pardi and Amazonas, and the Federal Territories of Acre, Amap~, Guapor6 and Rio Branco, which had previously been considered the responsibil'ty of the Servi~o Especial de Safide Pfiblica, and the major portion of the State of S~o Paulo, which is still supervised by the State Malaria Service. Recently the malaria control programme for the entire Amazon and Rio Doce valleys was transferred from the Servi~ Especial de Safide Pfiblica to the National Malaria Service. This has brought the number of houses receiving periodic D D T treatments to about 3,000,000. It is indeed a tremendous undertaking extending as it does over an area of 7,000,000 square kitometres. Often only the most primitive means of access are available to reach thousands of minute and isolated hamlets. e. T h e author writes t h a t for several reasons this p r o g r a m m e could not be completed by the intended d a t e . - - E d .

674

MALARIAL VECTORS OF BRAZIL

In the year 1946 we began by spraying 6,419 houses with DDT. This number rose to 2,364,267 in 1949 and has influenced a total population of about 12,000,000 so that the large majority of persons who previously resided in the malarious areas of this country are now being protected from that disease. As a result we are already observing a definite fall in malaria prevalence in this country. Chloroquine or " aralen " is being distributed freely throughout this Republic, each adult patient receiving gramme 1 orally in a single dose and children being given graded treatments according to their age. This type of therapy generally produces a symptomatic recovery but not necessarily a parasitological cure. Teachers, postal and telegraph clerks, railroad employees, padres, farmers, prefects and many individuals belonging to other professions and trades are utilized as local distributors of chloroquine. At the end of 1949 a total of 16,800 recognized distributors of this drug were on our lists. Since the first stage of our campaign is already largely completed, we are now beginning to attempt the limited eradication of anopheles mosquitoes as a step towards the eradication of malaria itself. Our attack on the Nyssorhynchus group, however, is only in its initial phase. House spraying with D D T has had little or no effect Ul~On the natural breeding of even so domestic a species as .4. darlingi. It will obviously be necessary, therefore, to attack both the larval and the adult stages of these mosquitoes if we are eventually to secure eradication of the disease. A start is being made on certain coastal islands where pilot projects will be tried out which may later be expanded to wider regions on the Continent itself. It is hoped that the army of investigators who are at work in other countries may help us as new and keener weapons are discovered for use both as larvicides and as therapeutic aids. The attack on the subgenus Kerteszia is also meeting with considerable success. Since 1943, when it was first proved that these anophelines were responsible for endemic malaria in. South Brazil, we have concentrated our efforts on destroying the bromeliads in which they breed. Both mechanical and chemical means can be used. We began the mechanical removal of these water holding plants in Floriandpolis, a city of some 35,000 inhabitants and the capital of the State of Santa Catarina. One hundred and twelve primary infections with malaria were registered in Floriandpolis in 1944 and 10,974,971 bromeliads were destroyed that year. The following year only 12 new cases of malaria appeared so we have continued with the manual removal and burning of bromeliads until by now more than 20,000,000 have been disposed of. At the present time the city of Floriandpolis is devoid of bromeliads and free of malaria. It covers an area of about 30 square kilometres and is continually being inspected for the reappearance of any new epiphytes. Although the manual removal of terrestrial bromeliads has given such excellent results at Floriandpolis, this technique has not been equally successful

~IARIO PINOTTI

675

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BEGAN

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CHART 2.--Blood parasite rates in two localities in the State of Minas Gerais before and after all houses had been sprayed with DDT.

676

MALARIAL V E C T O R S OF BRAZIL 25

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CHART 4.--Malaria morbidity in the capitals of the States of Piauf, Pernambuco, Alag6as and Espirito Santo during the 5-year period, 1945-1949.

MARIO PINOTTI

677

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CHART 5.--Malaria morbidity during the 5-year period 1945-1949 in four localities situated in the State of Rio de Janelro. ~.000

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CHART 6.--Malaria morbidity during the 5-year period 1945-1949 in five places situated in the Federal District.

678

MALARIAL VECTORS OF BRAZIL

in the forested regions. The tremendous dersity of bromeliads in the big forests surrounding the cities of Brusque, Blumenau and Joinville, reaches a figure of five plants per square metre. The mechanical removal of such plants is a difficult and dangerous operation, particularly when they grow on trees which attain heights of 40 metres or more, and unfortunately the reinfestation of cleared areas is very rapid. It therefore became necessary for us to cut down the forest around certain key centres of population with a subsequent programme of reforestation, utilizing types of trees which are not readily parasitized by bromeliads. In 1945 PrrTENDRIGH visited Brazil in order to demonstrate his technique of bromeliad destruction with copper sulphate solution, which he had developed in Trinidad. After observing the situation here, however, he felt that the methods used so successfully on that West Indian island would not be applicable to our very extensive forests which are frequently found growing in precipitous and inaccessible terrain. He therefore approved our programme of deforestation around the important cities which has already met with considerable success. The factories of Brusque in 1914 could hardly function because about half their employees were absent each day from work with attacks of fever. As the forest has been cut back from the environs of that town, however, this situation has changed completely. Although deforestation can produce the desired results around important urban centres in Santa Catarina, it is manifestly not to be recommended as a control method throughout the rural regions. In order to control malaria in urban as well as rural areas we are making a search for more efficient chemical herbicides which will destroy the bromeliads in which the kerteszias breed, without destroying the forest. Meanwhile, house spraying with D D T has been carried out over a wide area in South Brazil and has reduced malaria transmission to a minimum. We can thus experiment at leisure with potential methods for the final eradication of malaria from that region. A group of investigators is studying the ecological aspects of this problem as well as the effect of widespread application of copper sulphate, dichlorphenoxyacetic acid and other herbicides upon the bromeliads of this zone. We have high hopes that another 2 years will see significant progress in these studies of methods other than deforestation for the mass destruction of arboreal bromeliads. We might mention in addition that several attempts were made to control d. bellator and A. cruzii by spraying the forest with D D T and gemmexane from a helicopter. The results of those treatments were excellent so far as the immediate destruction of the sylvan mosquitoes was concerned. Forests in which between 200 and 300 A. cruzii had been captured per man-hour before treatment were completely freed of these mosquitoes on the day following the spraying with a helicopter. In a few days time, t!owever, the kerteszias began to reappear, so that at the end of 20 days the situation had reverted to its pristine state. As a routine measure, spraying forests with D D T from a helicopter is

M A R I O PINOTTI

TABLE I.

Locality.

Biraba

679

Blood parasite indices in a ~mmber of localities before and after D D T house spraying programmes were carried out.

Municlpio.

Barra

State.

Bahia

Year and month.

N u m b e r of specimens examined.

1947--Feb. 1948--Mar. 1949--Apr.

103 105 106

Index.

12.62 I

0-00

Bern Born

Casa Nova

Bahia

1947--Feb. 1948--Mar. 1949--Apr.

97 99 100

4-12 0.00 0.00

Bona Jesus da Laps

Born Jesus da Lapa

Bahia

1947--Mar. 1948--Apr. 1949--May

248 268 314

5.24 0.00 0.32

Malhada

Carinhanha

Bahia

1947--Mar. 1948--Apr. 1949--May

98 102 106

7.14 1-96 0,00

Ibotirama

Paratinga

Bahia

1947"Apr. 1948--May 1949--Apr.

134 171 176

14,18 1.17 0.00

Paratinga

Paratinga

Bahia

t947--Apr. 1948--Apr. 1949--Apr.

244 307 3]3

3.28 %00 %00

Parafuso

Camassari

Bahia

1948--June 1949--July

99 125

23,23 6,40

Monte Gordo

Camassari

Bahia

1948--Oct. 1949--Oct.

182 124

17.03 1,61

Guandfi

Ituberfi

Bahia

1948--Aug. 1949--July

253 253

8,30 0,40

A~'ti da Torre

Mata de S~o Jo~o

Bahia

1948--Dec. 1949--Dec.

85 122

27.59 4.10

Praia do Forte

Mata de S~o Jo~o

Bahia

1948--Oct, 19¢9--Nov.

117 104

30,76 2,88

Afligidos

S~o Gon~alo dos Carnpos

Bahia

1948--July 1949-July

108 106

19.44 5.66

680

MALARIAL VECTORS OF BRAZIL TABLE l--continued.

Locality.

Municipio.

State.

Year and month.

Number of specimens. examined.

Guaicui

Pirapora

Minas Gerais

1947--Apr. 1948--May 1949--May

55 35 102

Janu~ria

Janu~ria

Minas Gerais

1947--Apr. 1948--May 1949--May

659 630 724

S•o Romlo

S~lo Romlio

Minas Gerais

1947--Apr. 1948--May 1949--May

152 107 137

Guia do Pacopaiba

Mag~

Rio de Janeiro

1947--Sept. 1948--Aug. 1949--Apr.

105 123 123

Coroa Grande

Itaguai

Rio de Janeiro

1947--Sept. 1948--Sept.

97 99

Note.--In each locality listed in this table the pre-treatment index is the first one given. Subsequent indices were determined following the initiation of routine bi-annual sprayings.

not to be recommended, though it might be indicated in the case of a serious epidemic. We are indebted to Drs. R. M. TAYLO~ and HENRY W. KOMM, of the Rockefeller Foundation, for suggestions concerning the use of a helicopter for this purpose. The two principal methods which we are using for the control of malaria in Brazil are, therefore, the spraying of houses with emulsions of D D T and the destruction of bromeliads. Both of them are based on the biological characteristics of the proved vectors. The former is a general method and the latter a specific procedure directed against malaria transmitted by kerteszias. The results obtained are excellent and in bringing this exposition to a close we would like to present some blood parasite indices obtained before the D D T programme went into effect and in several subsequent years. These figures are given in Tables I and II and do not require any special comment, as they give an indication of what has happened in the entire region in which D D T house spraying programmes have been carried out. In the majority of the localities listed in Table II, D D T house spraying was not begun until 1947 and in some cases not until 1948.

681

MARIO PINOTTI

The last seven localities shown in Table II, namely, Paranagu~, Morretes, Brusque, Cabegudas, Blumenau, Itacorobf and Floriandpolis, are situated in the region where malaria is transmitted by Kerteszia anophelines. Most of the other places are located in regions where the vectors are either A. darlingi or TABLE I I .

Malaria morbidity in selected localities during the five-year period from 1945 to 1949 inclusive.

Locality.

State.

1945.

1946.

1947.

1948.

1949.

Terezina* ... ... Recife* ...... Olinda* ...... Macei6* ...... Vitdria *~* ...... Aracruz *e* . . . . . . Guarapari*** D u q u e de Caxias*** Japeri (ex-Bel6m)*** Caramujos*** ... Lajes **~ ...... Guapimirim*** ... Mag~ *** ...... Jurujuba*** . . . . . . Saquarema*** ... Maca6*** ...... C a m p o s *** . . . . . . Pirai*** ...... Queimados*** ... Maric~*** ...... Santa Cruz*** ... Jacarepagml*** ... Vig~rio Getal*** ... Ilha do G o v e m a d o r * * * Guaratiba*** ... Santos*** ...... Paranaguti* . . . . . . Morretes* Floriandpolis 0 0 " 0 ... Brusque** ...... Blumenau* . . . . . . • Cabe~udas** . . . . . . Itacorobl ~ ' * . . . . . .

Piaul ... Pernambuco...

2,623 1,654 718 1,468 2,832 329 359 2,757 172 153 56 504 1,804 656 166 2,358 609 180 64 432 583 1,828 627 161 694 107 1,880 93 1,288 2,0] 1 3,106 807 866

1,307 1,878 597 1,777 1,084 95 71 2,292 216 200 45 109 1,116 619 105 1,085 335 492 139 125 753 1,250 345 187 694 79 1,455 61 1,110 1,536 2,080 1,803 1,255

1,184 1,239 329 1,346 369 45 10 3,663 379 124 66 132 1,439 179 143 888 657 218 56 125 1,437 1,859 555 204 915 195 [ 1,345 36 1,755 1,289 1,874 2,210 1,168

1,959 1,890 836 1,697 86 21 i0 487 6 0 0 35 123 108 61 269 217 64 0 111 253 787 284 113 286 23 1,301 188 1,053 441 2,284 1,686 457

595 376 111 92 163 0 2 182 1 0 0 2 21 10 19 61 30 8 1 19 137 134 67 27 49 13 617 12 192 95 614 393 30

33,945

26,295

27,433

17,136

4,073

Totals

* ** *** ~***

......

= ~ = ~

AlagSas ... Esplrito Santo

Rio de Janeiro

Federal District

S~o Paulo Paranli ,~

... ... ...

Santa Catarina

H o u s e spraying with D D T b e g u n in 1949. Deforestation only. H o u s e spraying w i t h D D T b e g u n at the end of 1947 or early in 1948, Manual removal of bromeliada only,

682

MALARIAL VECTORS OF BRAZIL

In Brusque and Cabegudas malaria reduction was brought about by deforestation, while in Blumenau, Paranagmt and Morretes house spraying with D D T was more important, though partially completed programmes of deforestation may have had a beneficial effect as well. The only control method used at ItacoroN was D D T house spraying. Finally, at Floriandpolis malaria has been eradicated by the systematic removal of all bromeliads from the' urban area. The cases of malaria registered at Floriandpolis during the last 5 years were almost all infected outside that city. The reduction observed in 1949 represents the results of D D T house sprayings in the surrounding country. Likewise the 393 cases reported from Cabe~udas occurred in persons who lived in the surrounding countryside, where systematic D D T treatments were given for the first time in 1949. The geographical distribution in Brazil of A . darlingi, A . aquasalis, A . albitarsis, A . cruzii and A . bellator is shown in the foregoing maps. Charts 1 to 3 illustrate the fall in the blood parasite indices that has occurred in certain localities in the States of Bahia, Minas Gerais and Rio de Janeiro. The figures, from which these bar diagrams have been prepared, are given in Table I. Likewise, Charts 4 to 6 indicate in diagrammatic form data concerning malaria morbidity that have been assembled during the last 5 years in five States and the Federal District of Brazil. A . aquasalis.

REFERENCES. BUST/Uda_~TE,F. M., LACERDA,N., PARAeAMPOS,H. & SANTOS,O.O. (1949). Rev. bros. Malariol., 1, I48. CORREA, R.R. (1939). Rev. Biol. Hig., 9, 104. - & RnMos, A. S. (1941). Folia din. biol., 18, 183. DEnNE, L. M., CAUSE¥, O. R. & DEANE, M. P. (1948). Rev. Serv. esp. Saud. Publ., 1, 827. KOMP, W. H.W. (1937). Ann. ent. Soc. Amer., 30, 492. LUCENA, D . T . (1946). Folha reed., 27, 113, 121 and 140. PITTENDRmH, C.S. (1945). Report to the National Malaria Service. (Unpublished.) RACHOU,R. G. (1946). Folha reed., 27, 181. , LIMA, M. M. & LIMA, A.B. (1950). Rev. bras. Malariol., 2, 57. REY, H. (1947). T~ier. sob. Malaria, 11, 30. SOPEI1, F. L. &; WILSON, D.B. (1943). Anopheles gambiae in Brazil, 1930 to 1940. New York : The Rockefeller Foundation.