‘Eradication was a dirty word’: Anti-gambiae campaign, between cooperation and rivalry (1938–1940)

ABSTRACT

This article analyzes the efforts of the International Health Division of the Rockefeller Foundation (IHDRF) in its project initiative that resulted in the extermination of the African mosquito Anopheles gambiae from Brazil in 1940. This species, which originated in Dakar, Senegal, was identified in the Brazilian city of Natal in 1930, where insufficient local emergency sanitation actions enabled it to spread into the interior of the Brazilian northeast, causing an unprecedented malaria epidemic in the Americas in 1938, after years of silent spread. We will analyse the formation of Brazil’s Malaria Service of the Northeast (MSNE), discussing its political and scientific controversies and how the transition from the idea of extermination to the idea of eradication was consolidated in the political process of creating this successful sanitation campaign. In addition, we will discuss how the integration and transnational development of medical entomology at the time was a fundamental factor in the cooperation and challenges among scientists involved in this campaign. The international cooperation of scientists, albeit oriented towards the project of eradication of this mosquito, organised different research agendas and gained new insights into the global dissemination of mosquito-borne diseases.

KEYWORDS:

• Eradication
• Anopheles gambiae
• malária
• Rockefeller foundation
• Brazil

Introduction

On 23 March 1930, one kilometre from the port of the city of Natal, in Brazil, Raymond Corbett Shannon, an entomologist at the International Health Division of the Rockefeller Foundation (IHDRF)ⁱ was surprised to find larvae and pupae that had never before been recorded on the American continent. Shannon stated that the strange larvae and pupae in large numbers ‘showed me that I had a strange species and I thought it was new to science’. A few days later, upon returning to the laboratory of the Cooperative Yellow Fever Service (CYFS)ⁱⁱ and analysing the material, Shannon was able to confirm that it was the African mosquito Anopheles gambiae that had ‘for years been regarded as the most dangerous malaria vector in the world’ (Shannon, 1942). The arrival and spread of Anopheles gambiae, which originated in Dakar, the capital of Senegal, triggered health concerns about the problems of rapid transport and new transcontinental routes by fast ships and new air routes (Pinto, 1939).

An emergency action to contain two initial epidemics in Natal was followed by a period of silent spread across the states of Rio Grande do Norte and Ceará, from 1932 to 1937. This resulted in an unprecedented malaria epidemic in the Americas in 1938, when malaria transmitted by A. gambiae once more became a central focus of public health concerns in Brazil. This great epidemic of 1938 led to speculations about the possibility of this mosquito spreading throughout the Americas, after ‘spreading through the Amazon and reaching the Panama Canal’ (Benchimol, 2001, p. 169). Fears about the spread of this mosquito on the American continent led to the creation of the Malaria Service of the Northeast (MSNE), an anti-gambiae campaign that was the product of cooperative efforts between the Brazilian government and the IHDRF, which eradicated this mosquito in Brazil in 1940 (Lopes, 2020; Magalhães, 2016).

This article aims to analyse how the IHDRF’s efforts in Brazil focused on fighting the Anopheles gambiae mosquito, seeing it as an opportunity to demonstrate their effect on public health, starting in 1938, eight years after the identification of this species in the city of Natal. The project for A. gambiae extermination later became celebrated as a great feat of eradication. However, in the 1930s, the word eradication had a very ambivalent meaning for the IHDRF. We will show how, in this process, the idea of extermination was used to propose an anti-gambiae campaign and how the entomological studies of the time made it possible to count on what would later be considered eradication.

To understand the strategic shift of the IHDRF, it is important to note that the doctrine for fighting yellow fever up to the late 1920s was the ‘key focus theory’, which was based on reducing the density of mosquitoes to break the chain of transmission. As several studies have already shown, the IHDRF readjusted its focus when this theory proved to be demonstrably ineffective in face of the jungle yellow fever that emerged in 1932. This was because wild animals were found to be efficient animal reservoirs of the virus; hence, the temporary reduction of vectors would fail to break the chain of transmission, making the eradication of urban yellow fever virtually impossible (Cueto, 1995; Lopes & Reis-Castro, 2019; Löwy, 2017; Magalhães, 2016).

In the 1930s, therefore, there were two fundamental elements for the change in the approach and reorientation of the IHDRF’s efforts towards fighting the vector. The first was the discovery of the sylvatic cycle of yellow fever, while the second was the perception of the possibility of eliminating A. gambiae, based on studies led by Raymond Shannon in 1938 and on earlier research carried out by Brazil’s national malaria control programme, known as SOCM – Serviço de Obras Contra a Malária.^iii.

Strategically, given the risk of political instability in Brazil, and the setbacks in the first attempt to eliminate the main breeding sites of A. gambiae, the IHDRF chose not to dedicate itself to the African mosquito in the early 1930s, but instead to keep its focus on the CYFS. However, at the end of the same decade, the attack on A. gambiae would not have been so quickly articulated were it not for the prior existence of the CYFS (Benchimol, 2001; Farley, 2004).

Most of the historical research on the presence of A. gambiae in Brazil focuses on the SMNE's actions from 1939 to 1942, particularly from a political standpoint and the institutional role in mosquito eradication proposals (Magalhães, 2016; Packard & Gadelha, 1997; Stepan, 2013). However, medical entomology studies conducted by SOCM in 1938, prior to the Rockefeller Foundation's anti-gambiae efforts, are only mentioned in historical research published after 2019 (Lopes, 2019, 2020). We aim to emphasise how these antecedents were important in paving the way for the idea that A. gambiae would be an eradicable target, also considering the relations of cooperation and rivalry between the MSNE directed by Soper and the SEGE, led by Evandro Chagas.

The transition from the control of Aedes aegypti to the gamble on the extermination of A. gambiae indicates a clear change of focus. In the early 1930s, the so-called ‘silent spread’ of A. gambiae occurred after an unsuccessful attempt to eliminate the mosquito, largely caused by a political disconnect between the government of Getúlio Vargas and the IHDRF. In addition, faced with the problems of the return of urban yellow fever in Rio de Janeiro, the CYFS decided not to invest permanently against A. gambiae, taking only palliative actions (Lopes, 2019, 2020). However, in 1938, faced with the new conjuncture and unprecedented malaria epidemic in the Americas, the IHDRF increasingly focused its attention on A. gambiae.

We intend to emphasise the scientific and political undertakings of the period in two parts. The first involves the IHDRF’s policy change to discontinue its actions in the Cooperative Yellow Fever Service (CYFS), leaving this organisation under the responsibility of the Brazilian government in 1939, known as the National Yellow Fever Service (Serviço Nacional de Febre Amarela). Furthermore, we intend to show how research carried out in 1938, in cooperation with the SOCM, an initiative of the Brazilian government, favoured the wager on the possibility of exterminating this mosquito even before the Rockefeller Foundation formalised the anti-gambiae campaign with the Malaria Service of the Northeast (MSNE) led by Fred Soper.^iv.

The second part focuses on a discussion about how the MSNE anti-gambiae programme initiative attracted the interest of researchers in conducting parallel research, which led to a conflict between the Malaria Service of the Northeast (MSNE) and the Service for the Study of Major Endemic Diseases (SEGE), led by Brazilian scientist Evandro Chagas.^v.

In general, we will show how the policies linked to the actions of the IHDRF were interwoven by research agendas and scientific ambitions at the local level, and that there was a rich dynamic of partnerships and scientific rivalries within a larger context in which the aim was to achieve the extermination of Anopheles gambiae as a great public health feat. To a large extent, this had repercussions within the context of international health during subsequent decades.

‘Eradication was a dirty word’

The absence of actions to control A. gambiae resulted in its silent spread from 1932 to 1937 in northeastern Brazil. The spread of this mosquito through the states of Rio Grande do Norte and Ceará is attributed to several factors, including a decline in public opinion, since A. gambiae had already been expelled from the capital of Rio Grande do Norte in 1932, and the problem of droughts, which disguised its spread, reducing the concentration of cases but expanding the geographic area of the species. The return of urban yellow fever in the country’s former capital, Rio de Janeiro, also shifted the attention of federal authorities away from the northeast. It is important to emphasise the limitations of the IHDRF’s approach in Brazil towards diseases other than yellow fever during the period of the CYFS’s actions and its budget; these are elements recently discussed in detail in ‘Anopheles gambiae in Brazil: the background to a ‘silent spread’, 1930–1932’ (Lopes, 2019).

In the first years after the discovery of this mosquito in Brazil, the limitations of the CYFS approach were visible in the fieldwork, according to the testimony of Leônidas Deane, a Brazilian scientist who worked in cooperation with entomologists from the IHDRF. Despite the danger posed by Anopheles gambiae, the yellow fever vector was a priority in the early 1930s:

Shannon warned his boss, Dr. Soper, that they paid some attention [to the matter], but not that much, because they were all focused on yellow fever. So much so that the head of the service said: ‘But you, instead of looking for yellow fever, go looking for mosquitoes that have nothing to do with yellow fever!’ (laughter) Shannon was even criticized by his boss (Britto et al., 1994, p. 162).

This statement by Deane, in an interview with researchers from the Oswaldo Cruz Foundation (FIOCRUZ) in the late 1980s, is important insofar as it shows that, notwithstanding the vertical and focused proposal of the CYFS, entomologists like Shannon were in the field with an eye scientifically trained to go beyond the formal boundaries of the institution, or the specific objectives of a given campaign. Furthermore, Deane’s testimony indicates how A. gambiae was initially put on the back burner in the early 1930s, and only 8 or more years after its arrival was finally placed at the centre of an extermination campaign.

The role of Fred Lowe Soper, Shannon’s boss mentioned by Deane, is fundamental as a political leader who gambled on the idea of exterminating the African mosquito. Nancy Leys Stepan states it is impossible to think of the idea of eradication in the modern sense without placing Soper as a major defender of this proposal. We agree with Stepan (2013, p. 99) that the proposal to exterminate the mosquito was a ‘calculated gamble’. However, contrary to what Stepan points out, we consider that Soper’s purpose was not to navigate without crucial information about the mosquito. The species was little known and completely unpredictable, but preliminary entomological research before the beginning of the MSNE, carried out by Shannon, Gastão César de Andrade and César Pinto in Brazil, associated with studies conducted on the African continent by Alwen Evans, sufficed to underpin the extermination initiative more securely than Stepan appears to suppose.

Entomological studies about A. gambiae in Brazil started in 1938, headed by the Serviço de Obras Contra a Malaria (SOCM), before the Rockefeller Foundation entered the picture. This means it is important to recognise the work of Brazilian scientists as co-participants in the development of entomological studies that supported the idea of extermination of A. gambiae.

The surveys carried out for the implementation of the MSNE were largely informed by an international network of entomologists of which Shannon was a part and were based on research conducted by the SOCM, coordinated by Manoel José Ferreira. The SOCM had a laboratory in Natal where several experiments were carried out by César Pinto between November and December 1938. In 1939, the results were published in ‘Dissemination of malaria through aviation: the biology of Anopheles gambiae and other Brazilian anophelines’.

The SOCM’s work in Natal was fundamental to underpin biological studies, as well as to organise and select the literature on this mosquito and produce a scientific publication summarising the ‘most important biological facts of Anopheles gambiae published in several foreign specialised journals, which are not always readily available scholars far from the country’s major scientific centres’ (Pinto, 1939, p. 295). Raymond Shannon even visited the laboratory located in Natal and joined Pinto in performing a few experiments in late 1938. The laboratory was in operation from November 1938 to January 1939, when the MSNE began its activities, coordinated by the IHDRF. The continuity and scientific partnership between SOCM and MSNE researchers was also confirmed by Fred Soper’s words of gratitude to Manoel Ferreira: ‘Dr. Ferreira continued as an assistant to the new Service for the first 15 months of its existence, leaving it only after organising the Central Laboratory and seeing the Service well on its way to success’ (Soper & Wilson, 2011, p. 63).

Still within the context of SOCM, before the Rockefeller Foundation assumed responsibility for A. gambiae in Brazil, these studies helped to provide the necessary scientific basis for Soper to gamble on the extermination of this mosquito. In general, from the narratives about A. gambiae, it seems evident that Soper’s political brilliance overshadowed an entomological fieldwork that was decisive for institutional ventures linked to extermination.

Fred Soper’s growing interest in the extermination of A. gambiae is an important element that coincides with the proposal to demonstrate the effect. In a 1967 article on the prospects for eradication of A. aegypti in Asia, Soper, in retrospect, shows how the idea of eradication lacked institutional support from the IHDRF at the time of the actions against A. gambiae:

‘Eradication’ was a dirty word in those days. It became respectable with the eradication of Anopheles gambiae; […] The success of the Anopheles gambiae eradication programme in Brazil made the effort to eradicate A. aegypti respectable. There was no publicity on A. aegypti eradication until 1941, after Anopheles gambiae had been eradicated. (Soper, 1967, p. 646)

The IHDRF’s approach was that the idea of eradication had to be historically confined within the possibilities of its execution. In the late 1930s (before the eradication of A. gambiae), confidence in this idea was practically non-existent, reaffirming Soper’s statement. As John Farley (2004) also pointed out in his analysis of the IHDRF campaigns in South America and Sardinia, the failure to eradicate hookworm and malaria before the extermination of A. gambiae in Brazil in 1940 seems to have taken the word ‘eradication’ out of the official Rockefeller Foundation repertoire. The word seems to have been avoided even in the letters exchanged among the IHDRF leadership. However, it should be noted that in documents and letters related to A. gambiae, the word ‘extermination’ often appears as a more palatable way to refer to the intentions of eliminating this species in Brazil in the late 1940s. The word ‘eradication’ only became prevalent in documents and letters from the year 1941 onwards.

This process takes place within the analysis of the ‘cycles of eradication’, given that ‘The eradication of A. gambiae in Brazil was instrumental in rehabilitating the eradication concept after the failed experiences with hookworm and yellow fever’. (Cueto, 1995, p. 236). This faith in eradication and the expertise of Rockefeller Foundation staff was instrumental in guiding the institutional directions of public health at a global level.

In May 1938, in a letter from Soper to Wilbur Sawyer, director of the IHDRF from 1935 to 1944, Soper uses the word extermination very emphatically and deliberately for the first time to refer to A. gambiae.

Gambiae is different from the other Anophelines of this Continent; no one here is very familiar with its biology, and there is always the possibility that it may still be so limited in distribution, as to invite an attempt at extermination!!! (Letter from Soper to Sawyer, May 4, 1938. Record Group 1.1, Series 305, Box 16, Folder 138.)

In the same letter, Soper also explains that the actions against yellow fever were becoming dubious, a problem that could not be satisfactorily resolved within the framework of the IHDRF. However, he expresses his hope that the CYFS will be discontinued, and that yellow fever will become the responsibility of the Brazilian government, before making highly ambitious statements about his plans concerning the possible extermination of A. gambiae:

It is still too early to know just how the attempt to turn the Yellow Fever Service over to the Government will come out, and I shall make no definite suggestions regarding other activities until I am sure we are out of the woods on yellow fever. (Soper, 1938, p. 1)

In 1939, the CYFS ended its activities and the Brazilian government took over responsibility for the campaign against yellow fever through the newly established National Yellow Fever Service (SNFA). This transition also consolidates Fred Soper’s commitment to his project to exterminate the African mosquito. The timing is opportune for several aforementioned reasons: the use of the CYFS infrastructure, closer alignment between the government of Getúlio Vargas and the IHDRF (Benchimol, 2001; Cueto, 1995; Magalhães, 2016). One of the aspects that deserves emphasis is the importance of the maturation of Shannon’s studies on A. gambiae and understanding about this species’ behaviour vis-à-vis the rain cycle in the states of Ceará and Rio Grande do Norte and the mosquito’s vulnerability to drought (Packard, 2007).

The use of Paris green (copper acetoarsenite) to combat the larvae, combined with the limitation of mosquito breeding sites in the dry season, were fundamental to the strategy against A. gambiae. Furthermore, before the beginning of the MSNE in 1939, both Shannon and Brazilian entomologists were already familiar with the praised monograph of English entomologist Ms. Alwen Evans, ‘Mosquitoes of the Ethiopian Region’ (1938), which offered fundamental information about the habits of A. gambiae on the African continent, helping to elucidate how this mosquito could prosper in northeastern Brazil. Albeit rarely cited in historiography, Evans’ work is considered a classic by specialists involved in the fight against A. gambiae in Brazil (Lopes, 2019, 2020). Evans showed that despite its varied breeding sites, A. gambiae is a small pool-breeder, a species that breeds in small pools that are almost always, to some extent, exposed to direct sunlight. In addition, this species has a good flying ability of up to about 3 miles. At least these two aspects of A. gambiae proved essential in understanding the pattern of its spread in Brazil. The absence of information on larval habits in Evans’ study was complemented by SOCM experiments and surveys carried out in late 1938 and early 1939.

The MSNE was officially created in January 1939, based on the decree signed by President Getúlio Vargas. Earlier, in September 1938, the Rockefeller Foundation provided grants to the International Health Division to carry out surveys on the spread of A. gambiae. Shannon and Brazilian entomologist Gastão César de Andrade carried out a prospecting survey from October to late 1938, which yielded positive prospects (Soper & Wilson, 1945). This survey resulted in the ‘Preliminary Suggestions for an A. gambiae program’ presented by Shannon in December 1938, with a complete survey of the affected region and a plan of attack based on the habits of the mosquito identified by Evans (1938) on the African continent, where A. gambiae larvae were found in shallow puddles almost always exposed to sunlight. During this research work in late 1938, Shannon sent several letters to Soper describing his findings. His findings highlighted the role of the dry season in the plans to exterminate A. gambiae. In a letter dated late October 1938, Shannon already presents a strong hypothesis about the extinction of the species in the dry season, using Paris green: ‘undoubtedly the dry season will be about the only time of year in which one could go about the job of exterminating the species’. (Shannon, 1938, p. 1).

This survey also marks the beginning of the research partnership between Shannon and Brazilian physician Gastão Andrade, with the publication of the article ‘Dry Season African Mosquito, Anopheles gambiae in Brazil in 1938’ (Shannon & Andrade, 1940). In addition to engaging in important entomological research, including the CYFS, Andrade was also one of those responsible for the Ceará Division, where he worked with the MSNE from January 1939 to June 1942, and his participation in research on A. gambiae was fundamental.

The year 1939 is marked by several challenges, especially due to the problem of the rainy season and the spread of the mosquito in the Jaguaribe Valley, in the state of Ceará. In his correspondence with Sawyer, Soper emphasises the danger of the mosquito, describing it as an even greater threat than yellow fever: ‘It is only after seeing gambiae at work in Brazil that I have come to understand why West Africa has been called the white man’s grave’ (Soper, 1939, july 07, p. 2), emphasising the need to maintain the necessary resources to combat this mosquito in the year 1940.

The initial phase of the MSNE is marked by problems pertaining to the rain cycle and the spread of A. gambiae through the river valley, particularly due to the high concentration in the Jaguaribe Valley, and by pessimism about the undertaking of the campaign, especially regarding logistic problems, which appears at various times, especially during the rainy season. However, new research carried out by Shannon in late 1939 gives back Soper’s optimism:

Shannon has been three months in northeast Brazil and has returned more optimistic than even he was last year at this time. Shannon visited not only the infested area but the frontier zones and reports that he is truly surprised to find the region as clean as it is. (Letter from Soper to Sawyer, Dec 8, 1939, p.2 RAC)

Soper’s optimism was also due to the team’s work capacity and the positive result of the training courses conducted in the preceding months. Handling of the Paris green poison was adapted and systematized, which helped the MSNE to develop a technique that did require a sprayer. The use of this poison to combat larvae became more practical, as work became less dependent on equipment, increasing the mobility of application in A. gambiae breeding sites from the second half of 1939 onwards (Soper, 1966).

Fred Soper demonstrated ingenuity in his ability to seize the moment in terms of political articulation in the transition from CYFS to MSNE, but the scientific findings that supported his confidence in the extermination of the mosquito should not be underestimated. In the MSNE’s albeit only partial success story, Soper was the political authority that institutionally articulated the extermination of the invasive mosquito. On the other hand, Shannon was essentially the scientific authority within the IHDRF who provided the factual basis to support an essentially anti-gambiae operation. Soper’s feat would have been impossible without Shannon’s prospecting and the support of an international network of entomological research in the late 1930s. However, not all field researchers were engaged in the anti-gambiae project. From 1938 onwards, this mosquito provided a variety of attractive research opportunities, leading to a network of cooperation and scientific rivalries.

SEGE and MSNE, cooperation and conflicts

The elements that enabled Shannon and Soper to envision the possible extermination that should be taken advantage of is fundamental to the scientific conflicts that will occur between the MSNE and the Service for the Study of Major Endemic Diseases (SEGE), led by Brazilian scientist Evandro Chagas.

The new epidemic in Ceará and Rio Grande do Norte also caught the attention of Brazilian researchers, especially Evandro Chagas, who was in the midst of research on visceral leishmaniasis in Ceará, acting as superintendent of the Service for the Study of Major Endemic Diseases (SEGE). In July 1938, E. Chagas witnessed the advance of A. gambiae while working on research in one of the most affected regions (Benchimol, 2020). In a letter to his wife about the situation of malaria caused by A. gambiae, Chagas also stated his expectations about be the best way to proceed with respect to the new spread of the mosquito. To a large extent, his approach was aligned with Shannon’s proposals, affirming that only the established CYFS organisation would be able to contain the rapid spread of the mosquito could act with the necessary speed to prevent the insect from spreading even further. He also pointed out the importance of centralised federal coordination in a campaign moving from the periphery toward the centre (Chagas, 1938a).

The dialogue between E. Chagas and Shannon intensified from September 1938 onwards, with a meeting in Rio de Janeiro and information exchanges about the situation of A. gambiae in Ceará. In late September 1938, Shannon received instructions from the IHDRF to start a survey on A. gambiae in the state of Ceará, and he also received a timely invitation from Chagas to visit the SEGE laboratory in the same state, which he did in late September 1938. Shannon recorded his impressions of this visit in his diary, stating that the data on the epidemic caused by A. gambiae in the months of June and July, as well as the mapping carried out by Chagas in the region, were useful for his preliminary survey (Shannon, 1938).

E. Chagas was one of the first to also discuss the belief, widely publicised in journals in 1939, that A. gambiae could spread across the American continent, an idea that was widely used by Fred Soper to mobilise an anti-gambiae campaign. E. Chagas also warned that if such a centralised and organised campaign in cooperation between the government and the Rockefeller Foundation were not carried out, there would be a major risk of the mosquito spreading to the north, where ‘it will no longer be possible to fight A. gambiae and the entire Amazon region will be lost to the country’ (Chagas, 1938a, p. 2).

Anticipating that the Rockefeller Foundation would work ‘only on the gambiae problem’, E. Chagas suggests that SEGE would also focus on malaria, but ‘address the problem in other regions of the country’. This work would be organised ‘in cooperation with the Rockefeller Foundation, albeit without an interdependence of services’ (Chagas, 1938b, p. 192). E. Chagas had his own research plans for A. gambiae and, concurrently with the extermination plan proposed by the MSNE, he intended to focus his efforts on experimenting with insecticides indoors and on studies involving the administration of Atabrine to the sick. Atabrine, which was developed in the early 1930s, showed some efficacy against malaria caused by Plasmodium falciparum transmitted by A. gambiae. Indeed, the possibility of testing this drug against the dangerous malaria of A. gambiae became one of E. Chagas’ main interests as he headed SEGE’s research work in the state of Ceará.

In late 1938 and early 1939, Evandro Chagas participated in several meetings with representatives of Bayer in Brazil. As he points out in his diary, right at the beginning of his parallel work with the MSNE, negotiations were already underway and Bayer promised to provide ‘the amount we need of Atabrine for research in the northeast, free of charge’. (Chagas, 1939a, p. 2).

One of the first measures after the agreement between the SEGE and the MSNE was that, under the supervision of the MSNE, E. Chagas would be responsible for areas where he would have the autonomy to carry out research on A. gambiae, performing tests with insecticides to combat this mosquito in its adult form indoors, and experimenting with the administration of Atabrine. It should be noted that the SEGE surveys proved to be valuable to the MSNE, since the service organised by the Rockefeller Foundation would use all its resources to diligently carry out the proposed A. gambiae elimination plan to the best of its ability, leaving it up to the service led by E. Chagas to engage in research considered useful, as will be discussed concerning the extermination of A. gambiae. On the other hand, the SEGE benefited from the partnership, which enabled it to receive the support of the MSNE in the purchase of medicines and equipment, as well as infrastructure.

In 1938, during the articulation plan of MSNE as an anti-gambiae programme, E. Chagas’s objective was to negotiate the establishment of research sites in the state of Ceará in order to test the use of insecticide against A. gambiae inside homes and to apply the antimalarial Atabrine. However, in the implementation of breeding sites for his experiments a few months later, he demonstrated that the behaviour of the mosquitoes described by Evans (1938) could hinder his research work since it could make it difficult to isolate the mosquitoes:

In general, what was observed for the mosquito in Africa applies to Brazil. Particular attention was drawn to the fact that a flight capacity of three miles was found in Africa, which, if it also occurs in Brazil, will increase the complexity of the prophylactic method we are applying. (Chagas, 1939b, p. 61)

E. Chagas’ predictions were correct, and due to the configuration of the sites where active breeding sites were left, the mosquitoes were not restricted inside the predicted limits, but invaded other areas that were under the control of the MSNE. This caused numerous problems that made it impossible to achieve harmony between the research carried out by E. Chagas and the extermination project led by Fred Soper in the year 1940.

The research work led by E. Chagas reached its final format in 1940, covering four sites. According to the work proposal approved by the MSNE, the efforts were organised with the Grascismões site serving for purposes of comparison, Timbaúbas for work with insecticide, Araújos for anti-larval measures and ‘Macambira for both, anti-larval and spray work’ (Chagas, 1940a, p. 5).

This work took place concomitantly to the actions of the MSNE, and there was mutual support. Soper was intensely interested in understanding the efficiency of the insecticide, hoping to hasten the mosquito fighting methods. In 1940, after showing good results, Chagas’ work on the use of insecticide was fully integrated into the standard MSNE procedure, accelerating the elimination of A. gambiae. However, according to data concerning conclusions about this method, the use of insecticide inside houses was not the main method responsible for the elimination of A. gambiae in large areas, although it helped to accelerate the pace of extermination, as recognised in the MSNE’s report (Soper & Wilson, 2011, p. 231). Although the use of Paris green and the discipline of the officials responsible for detecting and eliminating larval outbreaks was the main strength of MSNE, the campaign against A. gambiae would not have benefited from the result of using the insecticide inside the houses without the actions of the SEGE.

As he gained field experience over the subsequent months, Chagas began to challenge the prioritisation of larvicidal work, such as the use of Paris green, and began to defend his method of combating the mosquito indoors in its adult form as the best way to deal with A. gambiae during the rainy season. SEGE’s initial research work begins to define its outlines within the mosquito extermination project, and E. Chagas claims his position as a scientific authority, seeking, not unlike the MSNE leaders themselves, to offer his own demonstration of efficiency in combating A. gambiae. Carlos Chagas did not limit himself to attacking the larvae. Given the mosquito’s preference for the indoors, it could be efficiently combated indoors using an insecticide. In fact, one of E. Chagas’ major ambitions was to follow in the footsteps of his father, Carlos Chagas, in the experimental use of insecticides; hence, the indoor fight against the invasive mosquito also had sentimental value and represented a scientific legacy (Barreto, 2012).

The tensions between SEGE and MSNE employees show a visible increase in April and May 1940. It is impossible to state the extent to which A. gambiae migrated to neighbouring sites, or to describe the pressure Soper and Wilson were under to exclude a mosquito breeding area in the midst of an intended extermination operation within the MSNE’s area of action. However, it is clear from E. Chagas’ reports that there is a strong complaint against the interference of MSNE officials in the SEGE service. This problem occurred with Dr. Gastão de Andrade, who carried out research work with Shannon in 1938 and who, in 1940, supervised one of the seven divisions in Ceará. For E. Chagas, Andrade seems to have ordered an intervention in one of SEGE’s experimental sites and would be carrying out ‘underground work’ counter to his experiments (Chagas, 1940b, p. 75).

During May 1940, the situation becomes unsustainable, E. Chagas was disturbed with the MSNE inspections. At the beginning of the parallel and independent work there was a climate of cooperation and mutual understanding and the notion of complementary work, but in E. Chagas’ report, the antagonism between the services is explicit when he expresses his disappointment and frustration:

We do not recognize in the MSNE technicians anything other than technical ability inferior to that of our staff, and we are getting fed up with the work methods and processes used by those who depend on the Rockefeller Foundation. We can see that a regime of discipline with frankness and honesty is very far from reality in the MSNE and that the system of discipline, through fear and lies, prevails everywhere. (Chagas, 1940c, p. 78)

E. Chagas’ distance from SEGE’s area of action in Ceará during the period in which he participated in the 8th Pan-American Congress in Washington as a delegate did not prevent him from continuing to argue against the MSNE’s actions. In one of his latest attempts to maintain some autonomy in his research, E. Chagas makes an ultimatum when responding to a telegram from the MSNE received in Washington:

We received a telegram from Ceará stating that the MSNE intends to survey adult rates in the Timbaúbas, Araújos and Macambira sites. We telegraphed Dr. Wilson expressing our disapproval, and we explained to both him and Dr. Pondé that the normal pattern of our research will surely be strongly disrupted if any kind of capture is carried out using insecticides in the areas where we are working. We told Dr. Wilson that we would be obliged to cease our cooperation with the MSNE if he insisted in this intention (Chagas, 1940d, p. 83;86).

On 6 June 1940, E. Chagas considered his experimental work lost due to the MSNE’s interventions in the Gracismões site, an area initially planned to remain completely free of prophylactic measures, where the behaviour of the mosquitoes would be observed. In the following passage, E. Chagas records the beginning of what would be the official transfer of the experimental sites from SEGE to MSNE, since, in his words, ‘our observations are already greatly impaired by the MSNE’s activity  …  We agreed, in principle, that it would be better to transfer control entirely to the MSNE’ (Chagas, 1940e, p. 94).

The approach used by the campaign was based on the division of the territory occupied by the mosquito, fighting chiefly the larval form of Anopheles gambiae, but also its winged form indoors from 1940 onwards, using insecticides. The two control measures were adopted on a large scale by the MSNE to exterminate the vector, using Paris green to kill the larvae and pyrethrum spray to kill the adult form of the mosquito indoors. The main technique to prevent contamination of new areas was to purge vectors that infested regions and to systematically monitor reinfestation sites and areas already free of Anopheles gambiae. The last focus of A. gambiae was discovered and eliminated in November 1940 (Soper & Wilson, 2011).

Final remarks

The transition from the SNFA to the MSNE was strategic and a calculated risk, and studies on this species in Brazil also depended on burgeoning knowledge about medical entomology on a transnational scale. However, although the proposed anti-gambiae initiative was limited to extermination, parallel research that was developed revealed a process of cooperation and conflicts, especially between the approaches adopted by MSNE and SEGE.

After the silent era, A. gambiae became an attractive object for scientific demonstration, be it for the extermination proposed by Fred Soper, or the tests conducted by Evandro Chagas. Initially, even working in concomitantly, the mosquito’s ability to fly and its unique behaviour caused it to invade neighbouring sites, giving rise to inevitable disagreements between SEGE and MSNE.

Historiography points to the continuity of the CYFS infrastructure and staff to the MSNE. However, as we have seen, the SOCM played an important role, especially at its laboratory in Natal, in conducting research on A. gambiae before the institutionalisation of the Rockefeller Foundation’s efforts to fight this mosquito in Brazil. These experiments, added to the network of Brazilian and American entomologists and to newly published research at the time, such as the work of Alwen Evans, appear to have provided the necessary scientific basis for Soper’s political success in convincing the authorities and Brazilian and American financiers to endorse the A. gambiae extermination project.

As we have shown, the prospect of the invasion of this mosquito throughout the Americas was not just an alarmist claim by Soper, but an opinion shared by several prestigious Brazilian scientists, including Evandro Chagas, a strong supporter of the MSNE in its early stages. Chagas, who already had an established research agenda in the state of Ceará, also pursued his scientific interests on A. gambiae.

Perhaps one of the most remarkable aspects of the history of Anopheles gambiae in Brazil was how, on several occasions, it bewildered scientists and health authorities. At first, due to its discovery by Shannon in 1930, later due to its ability to spread silently, favoured by its flying distance and by the rain cycle, rendering it a potential international threat. On the other hand, A. gambiae also surprised scientists by its fragility in the dry season. MSNE was started in 1939 and, the last specimens of A. gambiae (adult and larvae) were found in late 1940. The mosquito was exterminated faster than expected. As we have seen, Raymond Shannon attributed this success to several factors, but the most important one seems to have been the mosquito’s frangibleness in resisting the fight against the MSNE using Paris green in periods of drought.

After World War II, the IHDRF was assessed by the leaders of the Foundation, who concluded that new multilateral agencies such as the World Health Organization, based in Geneva, Switzerland, and its strongest unit in Latin America, the Pan American Sanitary Bureau (PASB, renamed the Pan American Health Organization, PAHO in 1959), headquartered in Washington, DC, were becoming the legitimate leaders of international public health. As a result, and progressively, the Rockefeller deemphasized health and refocused its activities on the Green Revolution.

Although a definitive decision to end the IHDRF was not taken until 1951, a number of officers of the Rockefeller moved to the new agencies, which took advantage of their experiences on eradication. For example, Fred Lowe Soper was appointed director of a refurbished PASB in 1947 (a position he would hold until 1959), where he eagerly promoted the eradication model attempted earlier. Almost at the same time, Marcolino Candau, a Brazilian who had worked under Soper in Brazil during the 1930s and was a firm believer in disease eradication, became the second director of the World Health Organization (WHO) in 1953, where he remained until 1973. In his new position, he dismissed the WHO’s early leaning toward sociomedical and holistic approaches and concentrated the agency’s focus on eradication campaigns (Cueto et al., 2019).

The first of such campaigns, run by both the WHO and PASB during the 1950s, was against the infectious disease yaws in Haiti, using penicillin. Although the campaign did not eliminate yaws, it reduced the disease significantly, enabling Soper and Candau to build an international consensus among politicians, foundations and government organisations – including the U.S. State Department – that the way to build health systems in developing countries was through eradication programmes. In 1955, the Eighth World Health Assembly that convened in Mexico City approved a major eradication campaign against malaria using DDT, drugs against the plasmodium and well-administered health programmes generously funded by the U.S. government (Cueto, 2007).

These campaigns embodied and multiplied the legacy of the Rockefeller Foundation in three ways. First, there was an assumption that the giver knew what was best for the receiver, namely, that elites, mainly foreign elites, could dictate what should be done. Secondly, that the key aspects of a campaign were technology and good administration, thereby overlooking social and cultural factors related to diseases. And lastly, that eradication would bring about not only physical wellbeing but was a means to construct the social and health programmes of the state. The debate about the advantages and limitations of eradication programmes would continue at the WHO and PASB for decades and was only brought into question in these organisations in the late 1970s, when a competing perspective emerged: Primary Health Care.

The eradication of Anopheles gambiae in Brazil came to be celebrated as a great achievement, obscuring a period when the word extermination seems to have been more convenient for the promotion of the IHDRF campaign. Fred Soper’s political strength, and his ability to grab the spotlight in furthering the feat of eradication, appears to disguise the moments of hesitation, setbacks, and unpredictability of a rich body of fieldwork that marked the challenges faced by entomologists in an era before the advent of DDT.

Acknowledgements

We express our gratitude to the Research Department at Casa de Oswaldo Cruz – Fiocruz and the reviewers for their valuable comments and suggestions on our manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – Brasil (CAPES) under grant number 001.