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History of Ecological Sciences, Part 46: From Parasitology to Germ Theory

2013; Ecological Society of America; Volume: 94; Issue: 2 Linguagem: Inglês

10.1890/0012-9623-94.2.136

2327-6096

Frank N. Egerton,

Environmental Philosophy and Ethics

Click here for all previous articles in the History of the Ecological Sciences series by F. N. Egerton Progress in parasitology and microbiology during the 1800s is one of the great triumphs of science. The consequences for humanity and domestic animals have been momentous, yet this story is not widely known in any detail. It is a story that was built upon achievements of the 1700s (Egerton 2008a, b) and parallels progress in phytopathology during the 1800s (Egerton 2012). In retrospect, it might seem like a rather small step from the accumulated evidence about plant and animal parasites during the 1700s to the establishment of germ theory in the 1870s–1880s. But that illusion is only plausible when one forgets that there are vitamin-deficiency diseases, scurvy, beriberi, goiter; genetic diseases, diabetes; and optically invisible viral diseases, small pox, yellow fever, which defenders of a germ theory could not explain to skeptics during the 1800s (Carter 1977, 1980). Disease causation was a very contested terrain, and Casimir Davaine seems to be the only investigator who contributed significantly to both parasitology and bacteriology. The discoveries within parasitology and microbiology during the 1800s came too thick and fast to be comprehensively surveyed here. This part surveys the high points and is divided into three sections: parasitology, microbiology, and the discovery of arthropod vector-transmission of disease. Discoveries in vector transmission were aided by the great progress made during the 1800s in entomology (Egerton 2013). We saw in part 44 (Egerton 2012:309–311; also Théodoridès 1966:195–196) that Italian Agostino Bassi (1773–1856) in 1835 first demonstrated an animal disease (of silkworms) caused by a parasite (a fungus), and in the early 1840s, immigrants to Paris, David Gruby (1810–1898) and to Berlin, Robert Remak (1815–1865), published on fungal diseases on human skin. French physician and biologist Charles-Phillipe Robin (1821–1885), who joined the Faculty of Medicine in Paris (Grmek 1975), published an important synthesis, Des végétaux qui croissant sur l'homme et sur les animaux vivants (1847), which he re-titled in a much-enlarged second edition, Histoire naturelle des Végétaux parasites (1853). Considering how relatively unimportant fungal parasites on animals are, it seems curious that this subject achieved such early prominence in parasitology during the 1800s. Although silkworm muscardine was fatal, most of the other fungal diseases of animals were not. (a) Karl Asmund Rudolphi. Humboldt University Library. (b) Japetus Smith Steenstrup. Early advances concerning animal parasites came in helminthology, the study of worms. Karl Asmund Rudolphi (1771–1832), considered the father of parasitology, was son of a Stockholm school teacher, studied medicine at Greifswald, where he wrote a dissertation on intestinal worms (1794). He completed a course at the Berlin Veterinary School (1801) and taught at Greifswald until 1810, when he accepted the chair of anatomy and physiology at the new University of Berlin (Foster 1965:17–19, Théodoridès 1966a:199, Kruta 1975, Penso 1981:255–256, Grove 1990:8–10, 816, et passim). His Entozoorum, sive vermium intestinalium (two volumes, 1808–1810) synthesized the knowledge on internal parasites, describing 457 species, with 629 references in a bibliography of 172 pages (Foster 1965:18). His Entozoorum synopsis (1819) described 552 distinct species and 441 names of what he considered dubious species. He thought parasites were “generated by disease in the body of the host” (Kruta 1975:592). He dedicated Entozoorum synopsis to Viennese museum curator Johann Gottfried Bremser (1767–1827), who also in 1819 published Ueber lebende Würmer im lebenden Menschen, with color plates superior to Rudolphi's black-and-white ones (Foster 1965:19, Farley 1972a:108–110, Grove 1990:9–10). (a) Félix Dujardin. Huard and Théodoridès 1959:74. (b) Casimir Joseph Davaine. Foster 1965: Plate 5. (c) Joseph Leidy. Reinhard 1958: Fig. 2. Japetus Steenstrup (1813–1897), from northern Jutland, taught school until he published two scientific works in 1842 that brought him fame and appointment as professor of zoology at the University of Copenhagen (Müller 1976). One work, a lengthy paper, discussed what one could learn from layers of dead vegetation in peat bogs, and became a foundation for paleoecology (Egerton 2009:49–52). The other was a book on the alternation of sexual and asexual generations in some invertebrate species, “one of the most illuminating generalizations in the history of biology” (Reinhard 1957:216–220, Foster 1965:20–23 + plate VI; Farley 1972a:117–119, 1977:58–60, Grove 1990:44–45). Alternating generations had previously been discovered in jellyfish, which he verified in Scyphistoma-strobila (Steenstrup 1845:11–25). Steenstrup also studied this phenomenon in free-living claviform polypes (Coryne) and salpae (Proles) (1845:26–51), and in three species of parasitic trematodes, including the liver fluke of sheep (1845:52–93, partly reprinted in Kean et al. 1978:11–13). He demonstrated what had been previously suspected, that an alternate generation of the fluke lives in snails. His book had three plates with many figures, explained in great detail. Steenstrup, son of a vicar, corresponded with Darwin, but never accepted Darwin's theory of evolution. Félix Dujardin (1801–1860), from Tours, had broad scientific interests, and turned to parasitology in 1837–1851 (Huard and Théodoridès 1959b, Foster 1965:23–24, 40, 113, Théodoridès 1966a:197, 199, Geison 1971, Grove 1990:10, 796, et passim). His Histoire naturelle des Infusoires (1841, 700 pages, 22 plates) was a major contribution to protozoology. He studied a variety of parasites, making important discoveries which were mostly synthesized in his Histoire naturelle des Helminthes ou vers intestinaux (1845, 650 pages, 12 plates), which was the beginning of nematology, the study of a particular group of worms parasitic on both plants (Raski 1959:386, Egerton 2012) and animals. (Nonparasitic nematodes in soil apparently consume bacteria.) Casimir Joseph Davaine (1812–1882), from St.-Amand-les-Eaux, conducted biological research while practicing medicine in Paris (Foster 1965:24, 46, Théodoridès 1966a:196, 201, 1968:196, 201, 1971, Grove 1990:13–14, 794, et passim). He made important contributions to both parasitology (example in English translation: Kean et al. 1978:349–350) and bacteriology (see below). He summarized his parasitology in Traité des entozoaires et des maladies vermineuses de l'homme et des animaux (1860, edition 2, 1877, partial English translation, 1863). Davaine also contributed to phytopathology, as another founder of nematology (Egerton 2012:320). Many worthy investigators described the life histories of multicellular parasites throughout the rest of the 1800s (see literature guide, below). However, dissecting the bodies of victims of parasites was insufficient for revealing the life cycles of many parasites having more than one kind of host. Experimental parasitology had begun in the later 1700s (Egerton 2008:424–425), but had not become standard practice. Parasitologist Ernst Friedrich Gustav Herbst (1803–1893), at the University of Gottingen, somewhat accidentally revived the practice in 1850 (Reinhard 1958:113–114, Foster 1965:72–73, Grove 1990:578–579). He dissected cats and dogs, searching for spiral fleshworms, Trichina (now, Trichinella) spiralis and afterwards fed the flesh to a caged badger. When the badger died, he dissected it also and found many Trichina in its muscles, which gave him the idea of feeding the badger's remains to puppies. Months later he dissected them and found Trichina in their muscles (Herbst 1851). James Paget (1814–1894), a London medical student in 1835, saw specks in the muscle of his cadaver and wanted to examine them under a microscope (Reinhard 1958:109–111, Foster 1965:69, Grove 1990:572–575, 813, Peterson 2004). Since St. Bartholomew's Hospital lacked one (!), he went to the head of the Natural History Department of the British Museum, who also lacked one, but advised that the Museum botanist, Robert Brown, had one. With Brown's microscope Paget discovered that each speck contained a spiral worm, which he sketched, and then gave an oral report to the medical students' Abernethian Society. London anatomist Richard Owen (1804–1892) named and described it (1835), crediting Paget as discoverer (Grove 1990:575–577, 812, et passim, Rupke 1994, 2004). In 1846, Philadelphia anatomist–naturalist Joseph Leidy (1823–1891) noticed specks in ham he was eating that resembled cysts of Trichina spiralis, which he had examined in human cadavers (Leidy 1846, Middleton 1923:104, Ward 1923:12–13, Foster 1965:74, 190, Ritterbush 1973, Grove 1990:577–578) and reported this discovery to the Philadelphia Academy of Sciences. The British Annals and Magazine of Natural History and the German Froriep's Notizen alerted Europe to Leidy's discovery (Reinhard 1958:113). However, Viennese parasitologist Karl M. Diesing (Grove 1990:3, 11, 27, et passim) decided, without seeing Leidy's specimens and probably without checking ham himself, that Leidy's Trichina must be a different species than spiralis, since it came from a pig, which he named T. affinis in his Systema Helminthum (volume 2, 1851). Since Herbst's experiment, feeding badger remains to puppies (see above) was also published in 1851, Diesing did not have a chance to learn from Herbst's experiment before misnaming Leidy's specimens. German physician Gottlob Friedrich Heinrich Küchenmeister (1821–1890), who had discovered that bladderworms were immature tapeworms (1855; Reinhard 1958:114, Foster 1965:41–42, 73, 75, Grove 1990:11–12, 579, 802–803), decided in his encyclopedia of human parasites (two volumes, 1855, English, 1857) that Trichina spiralis was an immature stage of the intestinal whipworm Trichocephalus dispar (now Trichuris trichiura), though he also suspected that Leidy's Trichina might be T. spiralis and not Diesing's T. affinis (Reinhard 1958:114–115). Three German professors gradually cleared up this confusion by experimentation. Gissen zoology professor (Karl Georg Friedrich) Rudolf Leuckart (1822–1898) in 1856 fed muscle containing trichinae to mice, and three days later he found young worms in the mouse intestines (Foster 1965:56, et passim, Théodoridès 1966a:201, Schadewaldt 1973, Wunderlich 1978, Grove 1990:805, et passim). However, he confused himself in his next experiment, in which he fed muscle containing trichinae to a young pig, then waited five weeks before examining its intestine. In the large intestine he found about a dozen mature Trichocephalus dispar, which he assumed were mature Trichina spiralis (Reinhard 1958:116). In 1859, Berlin medical professor Rudolf Carl Virchow (1821–1902) (Risse 1976, Grove 1990:580–581), obtained muscle with trichinae from an autopsy and fed the muscle to a dog, already weakened by a physiological experiment. Three days later, the dog died, and Virchow found Trichina worms, some containing eggs and others sperm cells. This undermined both Küchenmeister and Leuckart's conclusions. Leuckart confirmed Virchow's results and concluded that humans acquire Trichina spiralis from dogs (Reinhard 1958:118). Final clarification came from Dresden professor of pathology Friedrich von Zenker (1825–1898) (Grove 1990:579–587, 822), who in 1860 obtained from one autopsy Trichina cysts in muscle and free-living in the intestine. He wondered about the source of infection and learned that the victim had attended an employer's Schlachtfest four days before death. Zenker found the butcher who had prepared the ham and sausage for the celebration and obtained some of it, which was infested with trichinae (Zenker 1860). Virchow had continued his own experiments and had put together all the pieces of the puzzle except finding the adults in human intestine, which Zenker had done (Reinhard 1958:118–119). Virchow then demanded that all pork be inspected before being sold, and after a talk on this in Berlin in 1865, a veterinarian arose and insisted that trichinae were harmless. A physician challenged the veterinarian to eat some of Virchow's demonstration sausage; the veterinarian did and five days later became paralyzed (Reinhard 1958:121). England's first notable parasitologist was neither Paget nor Owen, but Thomas Spencer Cobbold (1828–1886), a graduate of the Edinburgh medical school in 1851 (Foster 1965:25–28, et passim, Kean et al.1978:393–394, Grove 1990:793–794, et passim, Bynum 2004a). In 1857 he moved to London, and in 1872 he became professor of helminthology and botany at the Royal Veterinary College. His Entozoa: an Introduction to the Study of Helminthology (1864) was enthusiastically reviewed because it rivaled texts from Continental Europe. His Parasites: a Treatise on the Entozoa of Man and Animals including Some Account of the Ectozoa (1879) “was not a new edition of his earlier book but an entirely new work with a far wider design” (Foster 1965:28). Leeuenhoek had discovered bacteria in 1683 (Egerton 2006:50–51), but had not linked them to disease. We saw in part 44 (Egerton 2012:310–311) that two European Jewish physicians, David Gruby and Robert Remak, identified fungal diseases of humans in the early 1840s. Possibly, they had read the speculations by another European Jewish physician, Professor of Anatomy and Physiology Friedrich Henle (1809–1885). He argued in his Pathologische Untersuchungen (1840) that contagious diseases are caused by living beings (Henle 1938:33–53, Hintzsche 1972), but he had doubted that it was yet possible to identify these parasites. His writings exerted some influence on Robert Koch in formulating his postulates (Carter 1985b). (a) Rudolf Carl Virchow. Wikipedia online. (b) Friedrich von Zenker. Reinhard 1958: Fig. 4. (c) Karl Leuckart. Reinhard 1957: Fig. 7. (a) Louis Pasteur in his laboratory. By A. Edelfelt. Bettex 1965:181. (b) Broth in flask with J. Balard's elongated swan neck. De Kruif 1926:81. Cohn's illustration of bacteria (1875). Ford 1939:85. (a) Ferdinand Julius Cohn. Wikipedia online. (b) H. H. Robert Koch. De Kruif 1926: facing 140. Based on photograph taken about 1883. (c) George M. Sternberg in 1869. Sternberg 1920: facing 2. Patrick Manson's drawings of embryo filaria (1877). From Foster 1965: Plate 7. Obstetrician Ignaz Semmelweis (1818–1865) noticed in 1846 that women giving birth in one Vienna clinic, aided by medical students, had a much higher death rate from puerperal fever than did patients in another clinic, in which women were aided by midwives (Risse 1975). He suspected that the medical students were transmitting infection from dissected cadavers to the women, and when the students washed their hands in chlorinated lime water, the death rates dropped sharply. He thought decaying organic matter from dissected cadavers caused the disease (Carter 1981, 1985a, Semmelweis 1983:245). He did make changes that saved lives, and in 1850 he was first to claim that childbed fever had only one cause (translated in Brock 1961:80–82). His Die Aetiologie, der Begriff und die Prophylasix des Kindbettfiebers appeared in 1861 (Semmelweis 1983 [English version]). Subsequently, predecessors, including Oliver Wendell Holmes (Holmes 1843), pointed to their own publications on contagiousness of childbed fever (Carter 1981). …in February 1861, M. Pasteur published his remarkable work on the butyric ferment, a ferment consisting of small cylindrical rods which possess all the characteristics of vibrios and bacteria. The filiform corpuscles that I had seen in the blood of anthracic sheep were much like the vibrios in shape and I was led to try and discover if this kind of corpuscle (or others of the same nature as those which determine butyric fermentation) when introduced in the blood of the animal would not act as a ferment. Davaine inoculated two rabbits and a rat with blood from a sheep that had died of anthrax and they all died in two or three days. He then inoculated another rabbit with blood from a rabbit that had died, and it died after 17 hours. He described the bacterium and suspected that it caused the disease. Pustules from humans with anthrax contained the same bacterium. He was unable to give the disease to birds or frogs. Two medical professors in Paris opposed him, but his responses to them convinced the Académie des Sciences to award him a prize in 1865. In 1866, Pasteur inhibited wine spoilage by heating the wine, and in 1868 Davaine applied heat to decontaminate anthrax blood (Théodoridès 1966:161–162). Spallanzani had apparently settled the spontaneous generation debate in 1765 (Brock 1961:13–16, Egerton 2008a:235), but Félix-Archiméde Pouchet (1800–1872) revived the debate in a brief article (1858), followed by his Hétérogenie, ou traité de la génération spontanée (1859). From Rouen, Pouchet studied medicine in Paris, then returned home to direct Rouen's Muséum d'Historie Naturelle (Crellin 1975a). He had published two noncontroversial previous books on sexual generation in mammals. He argued for the existence of a “force plastique” that seems reminiscent of Buffon's moules intérieurs and molecules organiques (Egerton 2007:147–148), about which naturalist Pouchet likely read in his younger years. His new suggestion was that life spontaneously generated as eggs, spores, or seeds (Bulloch 1938:92–95, Farley and Geison 1974:169). Chemist Louis Pasteur (1822–1895) had decided by 1852 that life was associated with molecular asymmetry, detectable by optical means, not characteristic of inorganic compounds (Sechevalier and Solotorvsky 1965:15–62, Porter 1972:1249, Farley and Geison 1974:172, Geison 1974:359–361, 1995, Salomon-Bayet 1986, Debré 1998). He therefore opposed the heterogenesis hypothesis. His studies of fermentation (1857–1860) showed that the process was not purely chemical, as Justus Liebig claimed (Holmes 1973:349), but a product of metabolism of yeast and other microorganisms Conant 1957a). This research strengthened his conviction that life does not arise spontaneously (Farley and Geison 1974:173–174). To combat the idea, he conducted experiments to show that air contains invisible germs (Bulloch 1938:96–102, Debré 1998:159–172). Spallanzani had shown that a broth heated and sealed in a container produced no forms of life, but his critics claimed the heated air prevented spontaneous generation. Pasteur needed to show that after the broth boiled it could be exposed to ordinary air with germs and still produce no forms of life. His former professor, Jérôme Balard suggested he place his broth in a flask, then heat the neck and draw it out into a swan-neck that admits atmospheric air but traps particles, including germs in the curved neck (Pasteur 1860, 1861, Conant 1957b:508–516). A committee from the Académie des Sciences presented Pasteur an award for his 1861 memoir. When Pouchet challenged Pasteur's results, the Académie appointed another committee that also favored Pasteur. Although these committees wanted to use Pasteur's results against Darwin's theory of evolution, Pasteur still deserved the prizes (Farley and Geison 1974:197). …fermentation and putrefaction “come together to accomplish the great destruction of organized matter, which is the necessary condition for the perpetuation of life on the surface of the globe. Life directs the work of death at every stage. The perpetual return to the atmospheric air and to the mineral kingdom of the principles that plants have taken from them is correlated to the development and the multiplication of organic activity.” Putrefaction restores to the atmosphere the water, the carbon dioxide, hydrogen, and ammonia without which life cannot exist. Extracting the oxygen and rejecting the carbon dioxide that will be taken up by the plants, the anaerobes are necessary to the cycle of life, for “the continual breakdown of dead organic matter is one of the necessities for the perpetuation of life.” Debré (1998:114) thinks that “Pasteur's research on fermentation created microbiology, which became the field of his next investigation.” In 1865, Pasteur accepted an appeal to study a catastrophic silkworm disease, which took six years to fully understand, and to learn about epidemics. Bassi's discoveries on fungal muscardine of silkworms (Egerton 2012) during the 1830s did not provide much guidance for understanding and combating pébrine in the 1860s. Being ignorant of zoology, Pasteur visited Jean-Henri Fabre to obtain a silkworm cocoon (Debré 1998:184–185). His investigation did not produce a straightforward understanding; he was reluctant to accept that a parasite caused pébrine (Steinhaus 1956:120–125, Geison 1974:374). Part of the problem was that there was also another disease, flacherie, that had to be distinguished from pébrine rather than being considered a stage of pébrine. Pasteur distinguished between these diseases in 1867, then accepted their contagiousness and developed ways for silkworm growers to avoid transmitting them. Eventually, it was learned that pébrine was a protozoan and flacherie a bacterial disease. The Franco-Prussian War (1870–1871) prompted Pasteur to study spoilage of beer, so France could avoid buying German beer (Porter 1972:1251–52, Geison 1974:380, Debré 1998:249–253). He extended his pasteurization process from wine to beer. The Pasteur Institute opened in 1888. Surgeon Joseph Lister (1827–1912) was the successful proponent of aseptic surgery, who transformed surgical procedures (Dolman 1973, Fisher 1977, Worboys 2004). His concern for infections from surgery led a colleague to show him, in 1865, Pasteur papers on spontaneous generation (1861) and putrefaction (1863), which inspired Lister to successfully use carbolic acid as an antiseptic (Brock 1961:83–85, Dolman 1973:403). He also faced formidable opposition, but was more successful than shorter-lived Semmelweis had been. Ferdinand Julius Cohn (1828–1898) was born in Breslau (now Wroclaw, Poland), son of a prosperous merchant, and allowed to attend the University of Breslau, but not allowed to take a doctoral degree there because he was Jewish (Geison 1971a, Hoppe 1983, Drews 1999, Matta 2007:95–151). He received his doctorate in botany at age 19, in 1847, from the University of Berlin. He returned to Breslau by 1849, supported at first by his father. He became an associate professor at the university in 1859, and in 1866 the minister of agriculture provided him with a new institute of plant physiology (Drews 1999:32, Matta 2007:146). In 1870 he founded Beiträge zur Biologie der Pflanzen, and he began devoting his research to bacteria. He applied to bacteriology principles developed for cryptogamic botany (Matta 2007:95). His Ueber Bacterien, die kleinsten lebenden Wesen (1872, English 1881) was the first general introduction to bacteria, including his dividing species into six genera, explaining that bacteria are nature's most widespread organisms. He recognized that they were responsible for the dissolution of dead organisms, allowing their material to be used again by new life, that they cause certain diseases—anthrax, diphtheria, blood poisoning, silk-worm diseases—and that they can be killed by prolonged high temperatures, but not by freezing.. There are no true bacterial species. On the contrary, the variability of bacteria is unlimited. The same species might, during generations of growth, assume different morphological and physiological forms which over the years sometimes would cause milk to turn sour or protein to putrefy, sometimes cause diphtheria or typhus fever, cholera or recurrent fever. Although bacteriologists now know that bacteria exchange genetic material in conjugation, change does not occur on as great a scale as Nägeli imagined. H. H. Robert Koch (1843–1910) was from a mining town, son of a mining official, whose mother and other relatives stimulated his interest in plants and animals (Dolman 1973a, Brock 1988, Lagerkvist 2003:59–84). He attended Göttingen University, 1862–1866, studying botany, physics, and mathematics, before switching to medicine. One of his professors was Jacob Henle, whose Handbuch der rationellen Pathologie (1846–1853) “reaffirms his previous convictions regarding the living nature of contagious agents” (Dolman 1973a:420). After practicing medicine in several places, Koch volunteered as a field hospital physician in the Franco-Prussian War. Afterwards, he resumed medical practice while also pursuing research. An anthrax epidemic focused his attention on that, bnd he verified Davaine's claim that rodlike organisms in sheep blood caused the disease. He invented techniques to culture anthrax bacteria in cattle blood and studied its life cycle, including spore formation and germination. He correlated his laboratory findings with seasonal prevalence of anthrax in livestock and asked Cohn for permission to demonstrate his findings to him. He did so, convinced Cohn, who had him demonstrate them to the medical faculty, then published them in Cohn's journal (1876 (1961). Koch carried bacteriological techniques beyond Cohn's, and his assistant, Julius Richard Petri, invented the Petri dish, used with agar and a nutrient to grow bacteria in a sterile environment. Koch's fame was rivaled only by Pasteur, for he discovered the bacilli for tuberculosis (1882) and cholera (1883). Koch is most remembered for his impeccable procedural postulates, for which he was partly indebted to Henle (Carter 1985b). Despite his postulates, his conclusions were not always accurate: the use of his tuberculin (introduced 1890) to treat TB was sometimes disastrous, and his claim that distinct human and bovine TBs could not be transmitted from one species to the other (1901) was proven incorrect. He was associated with four successive institutes from 1880 on (Brock 1988:251–252). He received a Nobel Prize in 1905 (Feldman 2000:242–244). As mentioned in part 44 (Egerton 2012), in America, Thomas Burrill introduced plant bacteriology in 1879 and George Miller Sternberg (1838–1915) introduced animal bacteriology in 1880 (Sternberg 1920, Gibson 1958, Williams 1960:125–128, Clark 1961:51–52). Sternberg had graduated from the Columbia University Medical School, but he did not learn bacteriology there. He taught it to himself while a U.S. Army physician. He also battled yellow fever at four different army posts, became infected with it at the fourth site, and barely survived. In 1879 he was appointed a member of the National Board of Health's Havana Yellow Fever Commission. Since yellow fever seemed to spread like infectious diseases, he believed it was caused by an organism, though his repeated microscope searches in the blood of victims failed to locate a causative germ. He was a skilled linguist—thanks to his mother—and he translated Antoine Magnin's textbook of bacteriology from French into English (1880), wrote an enlarged edition (1884), and finally published his own Manual of Bacteriology (1893). In 1880, he was sent to New Orleans to verify the European discovery of a bacterium that caused malaria. Instead, he showed that the Europeans were mistaken. He also showed that Pasteur's first announced discovery of the cause of rabies was in error. In 1893 he became Surgeon General of the U. S. Army. Burrill was “father of American plant pathology” (Campbell et al. 1999:109), and Sternberg was “father of American bacteriology” (Bordley and Harvey 1976:188). Some of the most devastating mammalian diseases are transmitted by arthropods and rodents (Busvine 1966:151–277, 1975:151–277, 1976). There were speculations in antiquity that insects were associated with diseases. Centuries later, Roman professor and papal physician Giovanni Lancisi (1654–1720) revived these speculations (Lancisi 1717) and recommended draining swamps to eliminate “maligna insecta” (Futcher 1936:546–548, Kean et al.1978, I:22, Egerton 2008b:413). He had both followers and detractors, but Patrick Manson (1844–1922) ended speculations with definite evidence (Manson-Bahr and Alcock 1927, Manson-Bahr 1962, Clarkson 1974, Harrison 1978:23–34, Haynes 2001, Bynum 2004b). He was from a Scottish village where, at age 11, he shot a “savage cat” and extracted from its intestine a long tapeworm. In 1857 his family moved to Aberdeen, where he attended school and in 1860 entered the Aberdeen Medical School, from which he received an M.D. in 1866. In 1867 he followed a brother to Formosa (Taiwan), where he studied tropical diseases, about which he previously had known little. In 1871 he settled at Amoy, an important Chinese port. He became interested in elephantiasis, as he often removed tissue from infected patients (Haynes 2001:36–55). Upon returning to Britain in 1874 for a year's leave, he found at the British Museum in 1875 a publication by Timothy Lewis (1872) based upon elephantiasis observations in India. Lewis found in the tumors a parasite, Filaria sanguinis hominis, which he believed was the immature stage of a larger adult worm. Manson wondered if the infection might be transmitted by mosquitoes. He had two medical student assistants in Amoy look for Filaria in patients' blood. One student could only work at night, and he found many more Filaria in blood than did the day student. By having students investigate patients' blood extracted every three hours, Manson found that Filaria were much more abundant in blood during night than day. His gardener, infected with elephantiasis, allowed mosquitoes to feed on his blood, and Manson found the worms inside the mosquitoes. Knowing little about mosquitoes, his early publications (1877, 1878a, b) contained misconceptions about their life cycle—that humans became infected by drinking water containing mosquito larvae—which he later clarified (1880, 1899). Alexis de Abreu published the first book on t