About structuring the study of parasites
W1.1 parasites and the empirical-analytical sciences
Of all the infectiological disciplines parasitic lore is the one whose special field includes the most colourful variety of ways. Because parasitism, perceived as a life form, is as old as cellular life on earth if organized in cellular units - if attributing parasitic RNA pieces also to parasites, parasitism is older than life itself. Excluding for conventional reasons these - today as "jumping genes" presenting - units and the prions, all "cadgering" biological entities are parasitic, because viruses, infectious malignant cells (canine transmissible venereal tumor, the Devil Facial Tumour Disease of the Tasmanian devil), bacteria, fungi, plants, protozoa, worms, as well as blood-sucking and lytic "higher" taxa exist through energy robbery, usually food robbery, without killing their host at once (ie, before or during the energy robbery) - even if they are rarely causing a disease which is leading to the death of the host lateron. Sometimes mistakenly regarded as "dead end" of evolution, parasitic units in truth are evolutionary highly successful, if not the most successful way of life on this earth. 30% of all animal species described are parasites. These animals have colonized every ecological niche on earth, they have survived every geological change and every era and eventually adapted to any protective measures of the hosts. Though parasitic lifestyles can be found within members of all the kingdoms of life, not all of these organisms are counted to the parasites sensu stricto:
The virology, bacteriology and mycology have become autonomous fields, the in the reception of the term historically preferential botany authorized the common use of the word, and all fields have left a salmagundi of not by them registered pathogens, pests, and vectors that are called parasites (sensu stricto) in the medical sciences, respectively. Them is nothing more in common than that, by definition, to be an eukaryotic, heterotrophic organism without a cell wall, that the host must belong to another biological species than the parasite, and that the Darwinian evolution rules can be applied to a large extent. Within the core area of the term "host of a parasite" lies undoubtedly man, Homo sapiens Linnaeus, 1758 (medically relevant parasites), and livestock, domestic animals, and pets (veterinary medically relevant parasites); as well as most other eukaryotic, heterotrophic organisms without a cell wall. In the outer area, however, are the plants. The Eubacteria, the Archaea, and the fungi are mostly outside of the term as commonly accepted. Certainly not within the area of the term belong the feeder on animal colonies and herbivores. This usual classification is, however, illogical and explicable only by the widespread disgust with these animals.
|Tab. I: Biological unit with parasitic types (s.l.) and their delimination (simplified)|
|class-II-transposons = self-seeking DNA-parasites||not an organism|
|viruses = DNA or RNA + proteins (+ lipid membrane)|
|prions = proteins (presumptive) without DNA and RNA|
|bacteria (incl. Chlamydia, Rickettsia, Mycoplasma) = prokaryote, mostly with cell walls made of murein||prokaryote||organism|
|Archaea = prokaryote mostly with cell walls made of pseudomurein|
|"plants", with cell walls||autotrophic,||eukaryote|
|fungi = eukaryote with cell walls made of chitin||heterotrophic,|
|free-ranging animals||"animals", without a cell wall|
|parasites sensu stricto = animals living at the expenses of a host animal of another species|
In medicine by historical reasons under the term parasite only animals are subsumed, which belong to the zoological taxa (mostly phyla = "blueprints") Protozoa, Platoda (Trematoda & Cestoda), Nematoda, Acanthocephala, Annelida, Arthropoda and Vertebrata.
Distinguish carefully a parasite infestation, a colonization of a host by a parasite with no apparent damage, and a parasitosis, a disease caused by an infection with a parasite. All thoroughly studied, as hosts suitable organisms are colonized by parasites. Most of them do not make the host sick, however. If this colonization is considered as pathological, there would be no "healthy" animals in the wild and no healthy human beings. Only in the case of a clinically manifest disease a parasite infestation is a pathological phenomenon and needs treatment generally.
The parasitology is the apprenticeship of an (animal) community to the detriment of the one and for the benefit of the other party, and thus a special case of the community ecology, the study of the relationships of organisms with each other within a community.
W1.2 recent definition of a parasite in the empirical-analytical sciences
Eisenmann : „Krankheit (durch ein Contagium animatum) ist Leben am Leben.”
Sprengel : „Parasitische Gewächse, dh diejenigen, welche auf anderen Organismen wachsen, sind nur dann wahre Parasiten, wenn sie ihren Nahrungsstoff unmittelbar aus den Säften lebender Vegetabilien in sich aufnehmen, . . . ” In: Brockhaus Encyklopädie, Leipzig 1838
Leuckart : „Als Parasiten bezeichnen wir alle diejenigen Geschöpfe, die bei einem lebenden Organismus Nahrung und Wohnung finden.”
Filiptschenko : „Der Parasit ist ein Organismus, dessen Lebensraum ein anderer Organismus darstellt.”
Piekarski : „Unter Parasiten verstehen wir solche Lebewesen, die zeitweise oder ständig ganz oder zum Teil auf Kosten eines anderen, in der Regel größeren Organismus, des sogenannten Wirtes leben, von ihm Nahrung, unter Umständen auch Wohnung oder ähnlichen Nutzen gewinnen und ihn bei geringer Anzahl nicht töten.”
Dogiel : „Parasiten sind solche Organismen, denen andere lebende Organismen als Lebensraum und Nahrungsquelle dienen, wobei sie die Aufgabe der Regulation ihrer Wechselwirkungen mit der sie umgebenden Außenwelt (teilweise oder ganz) auf ihre Wirte übertragen.”
Osche : „Ein Parasit ist ein Tier, dessen Lebensraum ein anderer Organismus, eben sein Wirt ist.”
Brockhaus Enzyklopädie : „Ein Parasit ist ein Lebewesen, das auf Kosten seines jeweiligen Wirtes lebt, ohne diesen unmittelbar zu töten, das ihn jedoch durch Nahrungsentzug, durch seine Ausscheidungen u.a. schädigen und dadurch parasitäre Krankheiten hervorrufen kann.”
Schmidt & Roberts : "Parasites are those organisms studied by people who call themselves parasitologists."
Hassl : Parasites (s.str.) are eukaryotic, heterotrophic organisms without a cell wall (formerly called animals), who live by energy robbery at the expense of an animal of another species, the host, whose physical integrity they hurt, but without killig the host before or at the beginning of the energy robbery.
Option: A parasites lives interactively together with an animal of a different species (host) for it´s benefit and the host´s disadvantage.
As flawed all definitions apply which include into the sphere gestations, pregnancies, milk supply and other assistance to members of the same species (for example young animals or senescent). A demarcation to the "pure" parasitism is very problematic and contradictory to our common sense in cases, in which (minke) males parasitize on or in the females of the same species, ingesting tissues of the sexual partner for the purpose of food acquisition. A familiar example of such a case is the frogfish Haplophryne mollis (A.B. Brauer, 1902). You can help yourself by viewing the fused animals and in the male parts reduced nearly only to the gonads as one individual of a hermaphrodite fish.
W1.3 opportunistic parasites
Definition of an opportunistic parasite: Opportunistic microorganisms are microorganisms that may or may not cause disease in the host. They generally colonize, but do not infect the host. Either an invasion or the multiplication and/or the answer of the immune system is lacking. In cases of an usual association with a host organism, they may be seen as a common microbiota. But, they can cause severe, even lethal disease if they are inadvertently introduced into a site, where they do not usually reside. This is the case if they invade unusual host tissues and/or if the immune system of the host is damaged. Because of the lowered immune answer, immunosuppressed persons or vertebrates are highly endangered by opportunistic infections. However, dependent on the type of the immunosuppression, the degree of endangerment is different. Opportunistic microorganisms are not detectable in expulsions of healthy adults, or, if they nevertheless arise, immunocompetent adults very quickly clear the colonization and do not get sick at all.
W1.4 parasites within an extended definition area and in other sciences
Transport parasites, not to be confused with parasites in paratenic hosts. The transport parasitism is now seen mostly in the form of a phoresy, as a temporary transportation party of an animal (phoret, guest) with another animal (phorent, host), which is used for the purpose of locomotion without damaging its integrity. On a closer view, however, the damage in the form of energy robbery is clearly ascertained. In parasitology transport parasitism is the case in free-living, facultative pathogenic amoebae of the taxa Acanthamoeba and Naegleria, which dislocate bacteria of the genus Legionella. The legionella unpredictably take the properties of poorly digestible forage, or of a phoret, or of a host-cell-lytic pathogen. In the animal kingdom a permanent surface colonization without unilateral damage (epoecia) can at best be postulated in the system barnacles and whales. But, even in this case, the increase in the sliding resistance is negated.
Brood parasites are found in the cuckoos, widow birds, cowbirds, honeyguides, and in some insect groups. Brood parasitism is the species-specific behaviour of some animals, not to hatch their eggs, but to manipulate surrogate parents, the hosts, to hatch them. The hosts also take over the subsequent feeding and management of alien juveniles, and they are thus damaged in their own reproductive success.
Fertility parasites there are such animals, in which the females are not fertilized with the species-specific semen, but reproduce by parthenogenesis. However, they need an insemination to initiate gestation, what for the sperm of another species is used. A well-known example is the - as an aquarium fish - ubiquitous molly Poecilia sphenops Valenciennes, 1846.
Kleptoparasites are especially found among birds. Kleptoparasitism, sometimes referred to for short as food parasitism, is defined as the deliberate exploitation of a proficiency of individuals of a different species for an immediate own benefit, for example, stealing food or making use of nests from an animal of a different species.
Social parasites harm especially ants, but also termites, bees, bumblebees and wasps. Social parasitism is defined as the relationship between two animal species, in which a state-forming, so called eusocial, species with a sterile worker caste or a species that has secondarily lost its worker caste, exploits the social system of another, also state-forming species, and thus damages the reproductive success of the host species.
Parasitoids are organisms, usually insects, which live as parasites during their individual development but always kill the host at the end of parasitism. They can be seen as a predator with a still alive prey during the feed. They are not considered to be parasites because of this way of life follows rather more the biological rules of predatism then those of parasitism.
Parasitic craters are a phenomenon of volcanism. They are the secondary craters on the flanks of a volcano complex, which are fed from the principal magma flow of the volcano.
Parasitic management structure is a contemporary term used in business organization. It is an organization form in which a senior executive without knowledge and without expertise leads or tries to lead a working group only by so-called key competences. The responsibility for the quality of the performing is passed down onto the skilled workers, but the benefits are reaped.
The term social parasite in the sphere of sociology is politically incorrect and ideologically burdened. It defines a person who wilfully and long lasting lives at the expense of the public welfare.
W1.5 history of the parasitic
The parasitological knowledge of prehistoric man may probably have resulted substantially from the own behaviour and from that of observable mammals that served as a systematic discarding of ectoparasites perceived as troublesome. Considering the evolution of man a positive feedback effect is undisputed between an interpersonal removal of lice ("grooming") and the formation of groups and group cohesion. Whether specific pharmacologically active food components were consumed to reduce the Ascaridian burden at least, is controversial; similar to observations in chimpanzees such considerations can definitely be postulated. Only in the case of the Guinea worm the traditional cultural notes and the etiological logic are strong enough pronounced to hypothesize a prehistoric perception of the "foreignness" of this parasite and its harmfulness to human health.
Culturally and historically interesting is the relationship between the art of hieromancy which is the viscera inspection, here specifically the inspection of the liver, and an actual infestation of farm animals by parasites. Developed between the 20th and the 10th century BCE and of enormous charisma, this art was still used in the early Roman oracles. It seems therefore to have obviously reached a certain, beneficial accuracy. Though the Haruspex deduces by means of very sophisticated knowledge sets via an exact exploring the surface of the liver of the sacrificial animal the will of the gods. Especially in the region where this art was developed, in Mesopotamia, the most common application seems to have been temporary, agricultural issues. Explicitly codified as relevant evidence are changes that we associate with the activity of liver parasites today (cit. Maul 2005). The traces left by the migration of larvae of nematodes and trematodes, the changes of the bile ducts by liver fluke infestation, and destructions caused by tapeworm larvae can undoubtedly be correlated with fertile, moist years and/or high livestock. The relationship with human well-being and productivity of the community will be understandable even today.
From a today´s perspective, the more millennial view on the "reversed" cause-effect relationship of (infectious) diseases is somewhat problematic. Already in Chinese medicine writings, the book Su-Wen, from the mid-26th century BCE there is an obvious description of scabies with instructions for removing the mite. The mite is however not regarded as the culprit but as a result of the disease (cit. Theodorides 1980). This idea, explained by the social circumstances and from the observation of persistent recurrent disease (nowadays re-infection due to the circumstances), maintains itself via the "European" four-humours-doctrine (humouralism) to this days in the form of the Traditional European Medicine (TEM). In biblical (Old Testament), Jewish and partly fundamental Christian thoughts a disease and the consequences of an illness is a punishment from God for evil deeds or for a failed life. This approach is particularly vulnerable to the search for a culprit, a villain, a hater of God, such as King David, whose deeds provoked an epidemic in Israel. In the Roman Catholic thinking the disease is not punishment and therefore the will of God, but an evil approved by God, often caused by sorcerers or witches allied with Satan.
Historically, for a long time a purely descriptive and therefore intellectually unsatisfactory "parasite skill", often in parallel with the above-mentioned sequence theory, be determined: The controversial parasite-associated citations of the Ebers papyrus (ca 1500 BCE), which names the ààà disease, possibly a dracunculiasis (cit. The Wellcome Trust 1996), the "fiery serpents" of the book of Numbers (ca 800 BCE), the Hippocratic flatworms, roundworms and ascarids (= pinworms) (cit. Hippokrates of Kos, ca 460-370 BCE), the Aristotelian "hailstones" (= cysticerci) of the pork (cit. Aristotle, 384-322 BCE), the intestinal worms and ticks in the Historia naturalis of Pliny the Elder (23 -79 CE), and the mentioning of the deadly sleeping sickness of the Emperor Mari Jata of Mali by Ibn Khaldun (1332-1406) (cit. The Wellcome Trust 1996) are described as pure observations, any correlation with an infectious entity is not established. Numerous Byzantine, Arab and medieval writings contain more or less accurate descriptions and lists of parasites of humans, the number of the forms described, today called biological species, continuously increases because in Europe each older text is recognized as a source of priority, and each author inflicts own knowledge. Even the first known book, which deals only with parasitic worms, Hieronymus Gabucinus´ De lumbricis alvum occupantibus ac de ratione curandi eos qui ab illis infestantur , is a largely descriptive work; nevertheless in it the view is taken that a cooling of the intestine leads to the emergence of tapeworms, which are then ejected during fever periods.
By contrast, from the view of Aristotle that lice and fleas emerge from dirt and sweat develops the hypothesis of a spontaneous generation of microbes, which was recognized due to the superior authority of Aristotle until the 19th century. In the Dictionnaire de medecine of the (nearly) physician Émile Paul Littré (1801-81) of  a citation is still found, that claims a parasitogeny in "frail and weak-minded beings". A final fatal strike against this hypothesis led at first or already Francesco Redi (1626-97), who showed in his work Esperienze intorno all generazione degli Insetti , that destructive maggots derived from eggs and not from a spontaneous generation in a cadaver.
According to Ackerknecht  the idea, that the epidemic occurring diseases are transmitted by infections and are caused by microorganisms, "seeds" or small animals, is very old, and it is recurring stylish in irregular cycles in the medicine. In fact, Marcus Terentius Varro, called Reatinus (116-27 BCE) writes in his work on agriculture Rerum Rusticarum (lib. I, cap. 12.) the following words on infectious pathogens: "animalia quaedam minuta, quae non possunt oculi consequi et per aera intus in corpus per os ac nares perveniunt atque efficiunt difficilis morbos . . ", translated: "Animals that are so small that the eye cannot see them, and passing through the air into the body through the mouth and nose and cause various diseases". This view was indeed considered with imperial support by the Imperator Augustus´ main architect, Marcus Vitruvius Pollio (ca 65-10 BCE), in the construction of homes in malaria areas; but it could not prevail against the all-covering Galen´s humouralism until the 19th century.
The medieval construction of separate municipal infirmaries and quarantine stations for travellers must be seen in connection with the epidemiological memory verse by Bernard of Gordon (1258-1318]: „Febris acuta, Phthisis, Pedicon, Scabies, Sacer ignis, Anthrax, Lippa, Lepra nobis contagia praestant” in English: Acute fever (= typhus), pulmonary tuberculosis, epilepsy, scabies, ergotism (= Anthony´s fire), anthrax, trachoma and leprosy are known to us as contagious (cit. Winkle 1997). Even the escape from the urban plague in the "healthy" chalets can only be explained from the assumption of an infectivity of the Black Death independent of God´s oeuvre (cit. Boccaccio 1353). One century later, however, only an infection associated with a demon´s opus approved by God was firmly anchored in the consciousness of the academically educated - ie an epidemic demonical possession (cit. Henricus Institoris 1486: I.18.42vb). But, the personal physician of three popes, Giovanni Maria Lancisi (1654-1720) noted that the number of fatal malaria cases fell sharply after the marshes were drained around Rome; whence in his script De noxiis paludum effluvis, eorumque remediis libri duo in 1717 he unsanctioned came to the conclusion that mosquitoes acted as vectors of pathogens, in doing so he postulated a "harmful substance" as the transmitted agent - and he negated with a square refusal any admission of evil by the omnipotence of God. However, these views about the contagiousness were considered as completely obsolete and as an anachronistic mistake in the first quarter of the 19th century, because the ineffectiveness of quarantine measures had putatively been proven irrefutable in yellow fever and typhus and cholera.
When in 1840 Friedrich Gustav Jacob Henle (1809-85) reintroduced the terms contagium vivum and contagium animatum and, thus, renewed the theory of microorganisms as the culprits of infectious diseases, he was not a precursor of a new era, but he was considered as old-fashioned. For example, in 1849 Carl Ludwig Sigmund (1810-83), hygienist of epidemic diseases at the k.k. General Hospital, thought that the plague is non-"contagious" and he also expresses the strong belief that the transmission successes only by the "atmosphere of the sick" (sic!). Withal it was 1836 when A. Donné demonstrated Trichomonas vaginalis as an overt infectious agent, then the second one testified in the world. The rise of a parasitology based on the idea of contagiosity took place in the second half of the 19th century in close entanglement with the development of powerful microscopes. The longest pendulum swing towards a pure contagious theory happened in 1884, when, for the first time and for the time being cursorily, some theses were announced from Berlin, that were later called Henle-Koch´s postulates:
Basically it applies in Medical Microbiology, if
1. a microorganism can be isolated from an infected host (ex vivo), and
2. a microorganism can be cultured in the laboratory (in vitro), and
3 a microorganism causes a similar disease to occur in each host, if this host can be infected with the microorganism, and
4. a microorganism infecting this experimental host can be re-isolated,
then, and only then, the microorganism is considered to be the culprit of a disease (= pathogen) and the disease caused by it is referred to be an infectious disease.
This linear, stringent formulation of a parasitic cause-effect relationship, embedded in a mechanistic worldview, were thought to form a supportive theoretical foundation for the military/sanitation-police-applied hygiene of the time; but already at the time of their formulation the postulates, were with such exceptions, which - viewed objectively - would have falsified the theory (eg mycobacteria). Today, the postulates are cited as a historical reference in papers about infectiology since AIDS, autoimmune diseases and opportunists have largely relativized them.
A new aspect in this old cause-effect debate was introduced by the creation of the hygiene hypothesis. This hypothesis states that the occurrence of various immunological disorders that have been primarily observed in humans at the last century such as Crohn´s disease, or the increase of the incidence in the era since hygiene measures were applied in developed countries, is attributable to the fact, that the load with parasitic worms is too low in childhood and therefore the immune system is not conditioned in time and not enough. At least some of our parasites turn out accordingly as "good guys" and their accommodation is useful for human health, they would then be regarded as symbionts! An acceptable parasitism could then be regarded as physiologically, a view that has incalculable effects on the strict malfunction concept of Western medicine. If this hygiene hypothesis is true, then it also results in the consequence, that individuals with an existing helminthic infestation have a significantly poorer immunological response than non-parasitized persons. Thus, the economic justifications of vaccination programs in the tropics should be reconsidered.
chronology of a parasitologically convincing designation of parasites
1835 Trichinella spiralis by Richard Owen and Arthur Farre
1836 Trichomonas vaginalis by Alfred Donné
1843 Ancylostoma duodenale by A. Dubini
1857 Balantidium coli durch P.H. Malmsten
1875 Entamoeba histolytica by F. Lösch
1880 Oscillaria malariae = Plasmodium falciparum by Alphonse Laveran
1894 Onchocerca volvolus by Rudolf Leuckart
1898 Leishmania tropica by Peter Fokitsch Borowsky
Nobel laureates for findings with a parasitological point of contact1902 Sir Ronald Ross (transmission of malaria)
1907 Alphonse Laveran (protozoan pathogens)
1926 Johann Fibinger (Spiropteracancer; an alleged universal carcinogenicity by a helminthic infection by Gongylonema neoplasticum in rats, in reality the effects of an experimentally induced vitamin A deficiency)
1927 Julius Wagner-Jauregg (therapy of a progressive paralysis by malaria)
1948 Paul Müller (Dichlordiphenyltrichlorethan = DDT as an insecticide)
2015 William C. Campell und Satoshi Omura (therapy of helminth infections), Youyou Tu (therapy of malaria)
W1.6 Dermatozoa-delusion or the Ekbom-syndrome
The term Dermatozoa-delusion goes back to von Ekbom  who gave distinction to it in his article Der präsenile Dermatozoenwahn. It is an organic psychosis, a cognitive disorder with tactile hallucinations. Sufferers have the delusional idea that parasites just located at the limit of visibility, usually worms or arthropods, are under their skin and/or move around there. This leads to severe anxiety and itching, which is usually combated with uncontrolled scratching. Patients are the immutable belief that they are infested with parasites, and the doctors or parasitologists generally provide incorrect diagnoses and are especially overwhelmed in their case. The absence of any clinical or parasitological evidence is not seen as a calming and clarification, but rather as a confirmation of their opinion, that their health is threatened by some undiscovered parasites. This resulted in 2002 in Pittsburgh / USA in a "renaming" of this syndrome as Morgellon Disease by biologist Mary Leitao, who believed her child to be affected by such mysterious intruders. She founded ado the Morgellons Research Foundation, to study what doctors and scientists did not seem to care for her inexplicably. But after a decade of wasted resources the CDC itself and the Mayo Clinic came to unanimous conclusion that "the invaders are not in the skin of those affected - but in their heads." The known reasons of the syndrome include cocaine and amphetamine abuse, alcohol withdrawal, CNS diseases and brain injuries. It is assumed that the delusion is related to the hormonal changes during the menopause. It affects more persons older than 40 years and more women than men. The diagnosis is usually not difficult, as the perceptual disturbances are obvious; the assignment of the patient to a specialist psychiatrist is usually impossible because of a lack of such psychiatrists and the fierce resistance of the patient. A treatment is often futile due to the lack of compliance because the patient almost always decide to refuse a psychiatric cause of their suffering and unshakably trust in somatic causes. Not infrequently, this situation will be exploited by charlatans and healers of all kinds, and even by fraudulent researchers as a supposedly risk-free playground (cit. Shelomi 2013) and the sufferers are exploited as an enrichment spring.
W1.7 My adequate publications
- wik117 Hassl A : Der klassische Parasit: Vom würdigen Gesellschafter der Götter zum servilen Hofnarren. Wiener Klinische Wochenschrift 117 (Suppl 4): 2-5.
W1.8 External adequate publications
- Ackerknecht EH : Geschichte der Medizin. Enke Verl., Stuttgart: 236 pp.
- Boccaccio G : Il Decamerone. Artemis & Winkler, München/Zürich: 886 pp.
- Eisenmann G : Die vegetativen Krankheiten und die entgiftende Heilmethode. J.J. Palm und E. Enke, Erlangen: 698 pp.
- Gabucinus H : De lumbricis alvum occupantibus, ac de ratione curandi eos, qui ab illis infestantur commentarius. Hier Scotum, Venedig: 168 pp.
- Hippokrates von Kos [ca 390 vChr]: Prognostikon. In: Capelle W. : Hippokrates Auserlesene Schriften. Artemis-Verl., Zürich: 238 pp.
- Institoris H : Der Hexenhammer. Malleus maleficarum. Dtv München: 864 pp.
- Lancisi GM : De noxiis paludum effluvis, eorumque remediis libri duo. Rom, 480 pp.
- Littré É & Robin C-P : Dictionnaire de médecine, de chirurgie, de pharmacie, de l´art vétérinaire et des sciences qui s´y rapportent . . . 14e éd. J.-B. Bailliére et fils, Paris: 1880 pp.
- Maul S : Omina und Orakel. Reallexikon der Assyriologie & Vorderasiatischen Archäologie 10: 45-88.
- Gaius Plinius Secundus Maior : Naturalis Historia: libri XXXVII.
- Shelomi M : Evidence of Photo Manipulation in a Delusional Parasitosis Paper. J Parasitol 99(3): 583-5.
- The Wellcome Trust : Illustrated History of Tropical Diseases. The Trustees of the Wellcome Trust, London: 452 pp.
- Theodorides J : Geschichte der Parasitologie. In: Sournia J.-C., Poulet J., Martiny M. (eds): Geschichte der Medizin, der Pharmazie, der Zahnheilkunde und der Tierheilkunde. Andreas & Andreas Verlagsbuchhandel, Salzburg: 2933-59.
- von Ekbom KA : Der präsenile Dermatozoenwahn. Acta Psychiatrica et Neurologica Scandinavica 13(3): 227-59.
- Winkle S : Geißeln der Menschheit: Die Kulturgeschichte der Seuchen. Artemis & Winkler Verlag, Düsseldorf/Zürich: 1538 pp.