An obstacle to colonization

The study of malaria and its control were so closely tied to colonization that these two legacies cannot be separated. The colonial project provided the reasons to study malaria, determined who was in a position to do so, and shaped knowledge generation and its application for malaria control, along with the distribution of its benefits [24–30]. As we show in detail below, the reason to study malaria was that it was the largest obstacle to colonization. Metropolitan military and business interests were compromised by the susceptibility of White settlers to malaria, which was by far the largest cause of death for that group. As historian Raymond Dumett has shown, in coastal cities such as Lagos and Freetown, White mortality averaged 70 or 80 per 1000 annually in the late 1800s, but colonizers in the interior fared much worse. In 1865 a British parliamentary committee had recommended largely withdrawing from West Africa altogether due to disease threats. When the Gold Coast was declared a colony in 1874, the first three candidates declined the Governor’s job because of the health risks; James Maxwell assumed the position on March 4th but died of malaria that same month [31]. Although reliable data are not widely available, some paint a devastating picture. For instance, for European troops in Sierra Leone from 1817–1838 average annual mortality was nearly 500 per 1000 [30].

The tremendous malaria mortality figures raise the question of motives for colonization. In the face of such fearsome odds of death, primarily from malaria, why did Europeans do it? The answer lies in perceived business opportunities and the development of state administrative mechanisms that favored some European interests, especially those in trade, shipping, and manufacturing using African materials. There had been substantial trade between Europe and Africa since at least the 1500s, centered mainly on slavery. When the international slave trade was banned by the British in the early 1800s it disrupted longstanding relationships that had been based mainly at European coastal forts. African rulers would sell captured enemies, among others, to European slavers at these places. As analyzed by economic historian Edward Reynolds, following the slave trading ban, Europeans sought trade in other products, including in raw materials such as cotton and gold, and in manufactured goods from Europe. Private trade favored an emerging class of African merchants who served as middlemen going between the coastal areas and customers living inland, where many Europeans would not venture due to the risks of malaria. Many African merchants had direct relationships with European manufacturers, but these and other arrangements were undercut by many disagreements [32].

As happened in other places, in the Gold Coast the British responded by trying to build legal and administrative structures that would let Europeans trade more easily and more directly with African customers, as Reynolds has analyzed. In economic terms, Chiefs had benefitted as the sellers of slaves, but trade in raw materials and products favored merchants, whose power grew over the early decades of the 1800s. Thus, at mid-century when the British proposed an alliance with Chiefs and pledged to establish a stable trade system, they found some agreement. To pay for the expenses of administration, the British asked Chiefs to submit to their rule and in 1852 announced a poll tax, non-payment of which was used to justify fines against Indigenous people. The right to collect the fines was then sold by the British government to private companies that wanted to be paid in local products such as palm oil. Ongoing disputes led to a series of Anglo-Ashanti wars and the declaration of a Gold Coast Colony by the British in 1874 [32]. Similar dynamics played out in other colonies, such as Nigeria [33], and as Elise Huillery has shown for French West Africa, colonial administrations were financed mainly via taxes on the colonized, rather than with metropolitan funds [34]. Thus, the main reason for colonization was to secure unfair trade advantages for European firms [32], although other motives such as religious conversion and racial discrimination were also prominent [35]. (There are many more comprehensive discussions of the political economy of colonization than is possible here [36–38]). The main obstacle to these objectives was malaria, which limited military control and threatened all European activities, especially in the interior. Hence, malaria became a critical threat to European colonial ambitions and a major priority for study and resolution.

A colonial priority and an academic specialty

The academic field of global health is a direct descendant of tropical medicine, which was founded around the turn of the 20^th century by former military and colonial officers searching for pay and prestige beyond what their governments would offer. The initial story centered on malaria research, but even as the remit of global health has become much broader modern observers will recognize many patterns established at the foundation of tropical medicine. Among many others, this includes the location of leading research institutions in metropolitan cities, the close links between these schools and metropolitan governments, the weak accountabilities toward the places and people who were objects of study, an emphasis on research questions and metropolitan concerns rather than health more generally, and a complete ignoring of economic and political subjugation in favor of a focus on pathogens.

One starting point for the story of tropical medicine could be dated to 1880, when the causal agent of malaria (the plasmodium) was identified by a French Army physician working in Algeria, Alphonse Laveran [39, 40]. Mosquito transmission of malaria was demonstrated in the 1890s by Ronald Ross, a British colonial officer in the Indian Medical Service [41]. Both men felt their research contributions were undervalued by their respective colonial services, and both used their parasitological celebrity to transition to full-time research careers that were independent but still closely associated with metropolitan and colonial governments [42, 43].

These moves to create an independent specialty around the knowledge and experience of successful colonial medical offices reflected powerful forces that created the first schools of tropical medicine, still leading institutions in global health. The first two were founded in 1898 in Liverpool, which Ross joined the following year, and London. Liverpool had dominated the English slave trade, followed by London in second place [44, 45]. The Liverpool School of Tropical Medicine was founded with support from the Elder Dempster shipping company, revealing the critical importance of malaria control to the private sector businesses that profited from colonialism [29, 46]. In the late 1800s, “British trading firms and chambers of commerce [were] the leading critics of West African health conditions [and] harassed the Colonial Office with complaints about the polluted ponds and wells, refuse-strewn streets and yards, and open sewage pits” as major threats to their own health and the profitability of their businesses [31].

The London School of Tropical Medicine was founded with support from the Colonial Office and voluntary contributions from the British public. This reflected the combined interests of Medical Advisor to the Colonial Office Patrick Manson, who had proven the insect transmission of disease as a colonial officer in Southeast China in the 1870s and later mentored Ross, along with businessman and Secretary of State for the Colonies Joseph Chamberlain [28]. Chamberlain had presided over the launch of both schools and at Liverpool’s inauguration declared “The fight against tropical diseases constitutes the real basis of the politics of colonization” [29]. The government enfranchised the two schools by requiring that all newly recruited colonial medical officers receive training at either one [47], thus granting a duopoly on mandatory education and tying them closely to the colonial project.

This pattern was followed by all the major European colonial powers, which founded their own similar schools in the years that followed. As historian Isabel Amaral has analyzed in the case of a school of tropical medicine in Lisbon (founded 1902), medical authorities used similar arguments to gain support. In her retelling, one proponent in 1901 captured the sentiment as follows:

Colonisation is not only a social and economic question but also a question of hygiene and pathology. The prosperity and wealth of a colony depend, first of all, on the ease of the living conditions to be found there by the colonists. The remedy to the serious risks presented by colonization undertaken blindly lies in the intervention of medicine together with the highly powerful resources that are currently available. England, Germany and France have demonstrated their recognition of this reality by creating centres for study and teaching that can easily be converted into colonial well-being and colonial prosperity [25].

Malaria was the motive force behind the creation of academic tropical medicine, a blend of laboratory science, medicine, hygiene, and public health that would be familiar to any current student of global health. Initially, this specialization had emerged within colonial governments, but quickly it split off into an independent academic profession. In part, this reflected stronger career incentives and opportunities for greater prestige [42, 48, 49]. The insights gained from scientific study were codified and advanced through elite, internationally oriented academic networks that functioned along lines of shared experiences and expertise in colonial settings, which were largely separate from existing domestic medical networks. Both Ross and Laveran were awarded Nobel Prizes for their malaria work (1902 and 1907, respectively), and Ross in particular spent much of his subsequent career complaining that physicians doing tropical medical research were not recognized or remunerated properly for their leading role in the colonial enterprise [42]. In launching the Société de Pathologie Exotique in Paris in 1908, Laveran cited facilitating colonial expansion and protecting the metropole as primary motivations [50], much as Manson had done a few years before at the foundation of the London School of Tropical Medicine [51].

In metropolitan consciousness scientific progress and service to empire blended easily with notions of humanitarianism, saviourism, charity and other paternalistic concepts that helped justify colonialism and disguise its non-merit hierarchies [52]. As Nancy Rose Hunt examines in the case of Belgian occupied Congo, metropolitan groups enhanced their own status by organizing around perceived health deficiencies of Indigenous people. These efforts fit colonial narratives of metropolitan superiority and charity as they sought to enhance the Indigenous labor force available for exploitation [53]. This pattern of mainly self-interested intervention by elite metropolitan researchers and clinicians has been noted in the global health era, as well [54].

Although these and similar schools were all in rapidly modernizing cities uplifted in a golden age of public health institution building and infrastructure construction [55], tropical medicine did not emphasize that knowledge or prominently feature its fundamental advances: sanitary sewerage, water filtration, or public administration [24, 28]. Instead, tropical medicine formed around laboratory and clinical aspects, particularly bacteriology, parasitology, and entomology. As Deborah Neill has analyzed, topical medicine was constituted through well-connected, elite, cosmopolitan networks that were cohesive across many European settings. They constituted their authority through international mutual reinforcement and did not connect closely with domestically oriented colleagues in their own countries [24]. Tropical medicine was one of the early “epistemic communities” that emerged in the late 19^th century around international research and policy concerns [56].

(The story of tropical medicine in the United States is roughly similar, with the founding of the American Society of Tropical Medicine in 1902 and the first independent school (Tulane) in 1912, although yellow fever was much more prominent due to American imperial ambitions in the Caribbean, and in Central and South America [57–60]).

A basis for racist inequality

Scientific findings on the details of malaria transmission quickly percolated into colonial policy. The close connection between academic tropical medicine and colonial administration came from shared experience, common goals, and mutual dependence. Many or all members of the emerging profession had been in colonial service or colonized places, wanted to advance colonialism, and wanted to solve the same problems in the same places as their colonial service counterparts. Hence, within a few months of retiring from service in India and joining the Liverpool School, Ross headed to West Africa on a malaria expedition at the request of the Colonial Office [61]. Ross and his colleagues recommended abandoning older, more expensive drainage strategies in favor of a more targeted attack on only Anopheline mosquitoes and their habitat, which would be cheaper, easier, and have the same effect on malaria as more general measures, they argued [61]. The recommended strategies also required the expertise of Ross and his colleagues, whereas more environmental measures did not. New knowledge about malaria transmission by Anophelines and the racist perception of Africans as a reservoir of disease led to an official Colonial Office policy of segregated living as of 1901. The construction of hill stations, separated European-only neighborhoods in cities, and separated lodging areas on plantations were quickly pursued throughout the British Empire [62, 63].

Racist segregation policies quickly led to a divergence of recommended malaria control measures, depending on whose well-being was perceived to be at stake. Much emphasis was placed on the appropriate location and construction quality of homes for Europeans. For example, in Freetown, official plans called for housing for Europeans at high altitude, at least a half mile from any Indigenous person’s dwelling, and featuring extra-large windows to admit salubrious breezes. This led to a conflation of segregation and safety—safety defined with sole reference to European concerns—while deploying the benefits of malaria knowledge almost exclusively for Europeans [63]. Racism underpinned the views of many in tropical medicine, such as Liverpool expedition member John Todd, whose letter home is quoted by Neill, “the climate is glorious and some day it will be crowded with white-skinned people who will wonder why their forefathers thought Africa so unhealthy” [24]. Similarly, colonial governments routinely dispensed quinine tablets for Europeans, but did not do so for Indigenous people. Writing in South Africa, one colonial medical officer explained the conditions under which malaria control efforts would be extended to Native people:

The unscreened native hut is…a very great danger to the farmer, particularly when it is only a matter of a few hundred yards or less away from his home. These squatter native families on Transvaal farms are a malarial menace on account of their being the reservoir of infection for the newly-born mosquito vector seeking its first blood-meal. Generally, we advise farmers to keep such huts a good distance—at least a mile away from European homes. Where this is impracticable, these native huts should at least be sprayed daily [64].

The narratives of colonial malaria control did not give prominent attention to the ways in which colonialism itself was responsible for increasing the distribution and worsening the consequences of the disease. As historian Randall Packard has investigated, large-scale agricultural practices, labor conscription, and forced migration all had disastrous consequences for the prevalence of malaria. Irrigation and dam projects created vector breeding sites where none had existed, forced migration spread the parasite by mixing infected and naïve populations, poor nutrition and poverty increased susceptibility, and land seizures forced Africans to live in unhealthy geographies they had previously avoided [26]. To a large extent, modernizing agriculture had produced similarly disastrous increases in malaria wherever it had existed, including in Southern England in the early 1800s. But the burden fell over the following decades with generalized improvements in environment and living standards, hygiene, and nutrition—all before the scientific insights of Laveran, Ross, and Manson [65]. The same thing had happened in the Southern United States, as well [66]. Following Packard’s analysis, these developments happened organically under normal conditions, but under colonialism, the continual extraction of economic surpluses, the enforcement of trade terms that disadvantaged Indigenous people, and governments that prioritized European interests all enforced an ongoing state of under-development that both promoted malaria and precluded public health responses [26].