Analysis of acanthocephalan literature published since 1900

lnrernutronulJourna/for Prinrrd in Great Brirarn

Parasimlogy

Vu/. 22, No. 2,pp. 181-186, 1992 0

ANALYSIS OF ACANTHOCEPHALAN LITERATURE SINCE 1900 D. M. MILLER*

002&7519/92 $5.00 + 0.00 Pergamon Press p/c 1992 Ausrralian .Socief.vfor Porosirolog~

PUBLISHED

and T. T. DUNAGAN

Department of Physiology, Southern Illinois University, Carbondale, IL 62901-6512, U.S.A. (Received 22 March 1991; accepted 30 September 1991) Abstract-MILLER

D. M. and

DUNAGAN T. T. 1992.

since 1900. International Journalfor

Analysis of acanthocephalan

literature published

Parasitology 22: 181-186. The data for this study are based on more

than 6000 articles that mention Acanthocephala. The results indicate: (1) the difficulty in being current on world literature. It took about 3 years beyond the date of publication to discover many articles. (2) Except for World Wars I and II there has been a sustained increase in the number of articles. At present this rate exceeds 1000 titles per 5-year period. (3) Investigator interest, as measured by multiple publications by a given author, has remained very small. (4) Most publications have originated in the U.S.S.R. and U.S.A. followed by Great Britain and Germany. (5) Number of authors per title has increased dramatically. Currently, there are more four-author than single-author articles. (6) Fish are host animals most likely to be mentioned as containing acanthocephalans. INDEX

KEY WORDS:

Acanthocephala;

literature;

bibliography.

We have focused century.

INTRODUCTION AN

analysis

of

Acanthocephala

all would

publications begin

that

mention

in the 17th century

of Redi

MATERIALS

in 1684, according

* To whom all correspondence

published

this

with

to Liihe (1905). However, the number of publications which appeared before 1850 is small. In 1811, Bremser, according to Petrochenko (1956), described 31 species which brought the total to 52. Later research proved many of these species to be identical to previous descriptions but Bremser’s work did focus for the first time on the importance of the host in the systematics of Acanthocephala. It wasn’t until the later part of the 19th century that investigators expanded their work to include details of morphology and development. Publications which provide a general review of taxonomy include Meyer (1932), Petrochenko (1956) Golvan (1958, 1959, 1960) Yamaguti (1963) and Amin (1985). Other aspects of acanthocephalan biology are described in Crompton & Nick01 (1985). Despite the large number of practising scientists and the large amount of support given to research, the study of all aspects of the biology of Acanthocephala has lagged behind that of many parasites. This lack of interest has provided an opportunity for examining the literature on Acanthocephala in a way that would be very difficult for a huge group like the nematodes. the work

the study on papers

AND METHODS

Collecting the world literature on any subject is an awesome task, even if the group has only about 1200 described species. We limited our endeavours to this century believing that these references would be more useful than older ones, and that the important very old literature would appear in bibliographies of other authors of this century. Helminthological Abstracts, Zoological Record, Index Catalogue of Medical and Veterinary Zoology and Current Contents provided the initial sources that were screened. These were supplemented by reviewing hundreds of journal articles. The search has currently produced approximately 7000 references. Even so, we do not claim to have found every reference that mentions an acanthocephalan. We are particularly aware of our shortcomings in discovering items from the Soviet Union and East European countries. Furthermore, we have attempted to include only abstracts and a few dissertation titles quoted by other researchers. In a task of this type, one encounters many references whose titles suggest that acanthocephalans are mentioned in the text. However, our data base includes only entries that we or others have mentioned that they are actually present. This bibliographic data base was begun in 1984 with approximately 1000 references as text files on an Apple computer. When the Macintosh 512 became available, the data base of 4000 plus references was moved as a text file and then converted to a bibliographic program called BookendsTM. Since that time, the bibliography has been revised and converted into an End NoteTM program. Presently the entire

should be addressed. 181

182

D. M. MILLER and T. T. DUNAGAN

bibliographic data base resides on a Macintosh SE Computer with a Radius 25 MHz Accelerator Board, a 68881 coprocessor chip and 100 Megabyte hard disk. While the entire data base consists of approximately 7000 references (from 1684 to present) which contain references to Acanthocephala, only those from this century are pertinent to the study. Each reference is indexed for Author, Year of publication, Genus, Species, Original description of a species, Original description of a genus, Host (Invertebrates other than cephalopod, cephalopods, fish, cyclostomes, amphibians, turtles, lizards, snakes and other reptiles, birds, mammals, primates and man), Journal or book, Country of publication, Type of publication (survey, ecological, morphological, biochemical-physiological, bibliographic, taxonomic, textual, life cycle, immunological, pharmacological, evolutionary, hyperparasitism or alternate host), and Functional anatomy (proboscis, neck, hooks, nervous system, lemnisci, reproductive, body wall, muscles, lacunar-circulatory, excretory, receptors, chromosomes-nuclei, nutrition. and hormones). The entire bibliography can be searched for up to five fields at once and search time for any of the categories is less than a minute. All foreign characters (e.g. a, c, D, z) are supported and sort properly. References can also be formatted for any particular journal style.

RESULTS Figure 1 is a graph showing the total number of world-wide and United States publications on Acanthocephala as a function of 5-year periods from 1900 to 1979. The data (not plotted) indicate that there are fewer than expected publications from 1980 to the present. We believe that this is an artifact of collection. It takes about 34 years for most titles to appear in available literature but sometimes longer than this for those in more obscure publications. Historically this has been particularly true for some East European and U.S.S.R. literature. A recent item in Helminthological Abstracts for 1990 illustrates this point. Item 1543, an abstract of Chandra, Rao & Shyamasundari (1987) was actually published in 1987 in a journal dated 1984.

The overall pattern of publications (Fig. 1) as measured world-wide and in the U.S. clearly shows that political events may exert several changes in the rate of publication. The major world-wide decreases occurred between 1915 and 1919 (World War I) and 1939 and 1945 (World War II). In contrast, in the U.S. there were no decreases during this time and the curves are rather flat indicating a constant output of publications. However, note the drop between 1955 and 1960 (Korean War) which is reflected only in U.S. data. Rapid increases occurred world-wide beginning in 1945 and 1960 and appear to continue at a high rate. Interest in Acanthocephala as a parasite is reflected in Fig. 2. This graph depicts the number of times a given investigator has included Acanthocephala in a separate publication. A total of 3000 different authors are represented but only a little over 2000 appear as first authors. Fewer than 20 authors have appeared in 30 or more papers and less than 10 have written 50 or more papers. In this last group five of the most published authors are from the U.S.A. but none were students under H. J. van Cleave, the most prolific author on Acanthocephala. Host countries of investigators writing 30 or more papers (listed in alphabetical order) are: Australia, Brazil, Finland, France, Great Britain, Japan, the U.S.A. and U.S.S.R.

5

1000

I

100 ORDINAL

NUMBER OF AUTHOR

FIG. 2. Number of acanthocephalan publications per author plotted against the ordinal number of the authors. 600 400 200 0

FIVE YEAR PERIODS

SINCE

1900

FIG. 1. Total number of world-wide and United publications on Acanthocephala plotted against periods since 1900.

States 5-year

The number of authors per paper (Fig. 3) has gradually increased since 1900. Single-author papers have become the exception rather than the rule. Moreover, following the explosion of dual authorship in the mid- 1950s three-author papers increased in the early 1960s. Four- to six-author papers began in the mid-sixties with four-author papers currently more abundant than single-author works. Papers with more than six different authors now appear with increasing frequency but the numbers are still small (Fig. 3). The

Acanthocephalan

183

literature since 1900

1000 Single Author Two Authors

0 0

Three Authors Four Authors

+ m

Fwe Authors Six Authors

2500

-e-

Total Pub

2000

0 0

m 5 100 F 3 2 B 5

10

z

YEARS

FIG.

4. Total number of papers, authors and unique authors plotted against IO-year periods for the years 190&1989. Unique author is defined as an author only being counted once during a year period regardless of how many publications on which he is listed as author and in what position.

YEARS

FIG. 3. Number of publications on Acanthocephala with different numbers of authors plotted against 5-year periods for the period 19OC1989.

average number of authors per paper for 1900-1909 was 1.06, for the period 1940-1949 it had climbed to 1.26 authors and for the period 1980-1989 it was 2.36. This would, on first appearance, indicate that the number of workers in the field is increasing at an expanding rate. However, it may also mean that more authors are publishing more than once in the given time period or simply that additional authors are being added to the papers. To determine to what extent each of these were occurring we plotted the total number of authors by IO-year periods, the total number of papers per IO-year period and the number of ‘unique’ authors per IO-year period. We define ‘unique’ author to mean that an author is only counted once during a l-year period regardless of the number of times that he or she may appear on publications or regardless of position. H. J. van Cleave published 11 papers in 1920 that discussed Acanthocephala but he would only be counted once as a unique author by this approach. Thus the curve for the ‘unique’ authors, when compared to the total number of publications, gives one a measure of the number of authors being added. The difference between the ‘unique’ author curve and the total number of authors provides an appreciation for the increase in multiple authors during that time period. It is clear from Fig. 4 that from 1960 to the mid-1970s both the number of multiple author papers and the addition of authors to papers have occurred at an increasing rate. After the mid-1970s however, the

number of ‘unique’ authors decreased in spite of an increasing number of total authors. The distribution of scientific papers by country or region of origin of the journal or book is presented in Fig. 5. This figure indicates that publications originating in the U.S.A., U.S.S.R., England and Germany, in decreasing order, account for most of the information on Acanthocephala. The position of the U.S.A. and U.S.S.R. will likely switch when more of the U.S.S.R. literature (especially survey literature) is available to us. Notice that researchers in large geographic areas such as China and Africa have not published extensively during this 90-year period.

GEOGRAPHICAL

AREAS OF THE GLOBE

FIG. 5. Numbers of publications which mention Acanthocephala plotted against the geographical area of the journal in which the publication appeared.

The distribution of publications in IO-year periods against host organism (Fig. 5) and the number publication plotted against host and country of publication is based on 4000 of the 6021 titles in our data

184

D. M. MILLER and T. T. DUNAGAN TABLE ~-PUBLICATIONS ON THEOCCURRENCE ok ACANTHOCEPHALA IN DWERENT HOSTSLISTEDBY Asia

Americas

Africa

Europe

Australia

I

Other

Invertebrates Fish Amphibia Reptiles Birds Mammals

I1 193 11 9 44 94

91 616 54 66 265 613

2 19 0 2 13 34

85 761 83 36 385 330

14 442 44 16 175 282

21 4 3 IO 61

2 25 2 0 7 19

Totals

362

1711

70

1680

1033

100

55

GENERAL GROUPS

OF HOSTS

FIG. 6. Number of publications on Acanthocephala divided into 30-year periods and plotted against the animal hosts mentioned.

FIG. 7. Number of publications on Acanthocephala divided into 30-year periods and plotted against the overall thrust of the publication.

causes the 1980-1989 period to have fewer reports than expected. In Fig. 6 the host species are listed in decreasing ordinal position of the total bibliography against major land-mass areas of the world. These plots show that with slight deviations, the ordinal sequence of the hosts is a function of the more developed countries. The changing interest of investigators is shown in Fig. 7. Based on 30-year blocks, there has been an increased number of publications in all categories but notice the shift of interest from taxonomy to ecology as well as the growth of chemical studies. Notwithstanding these trends, more than half of the titles are the results of surveys. print

species are currently known. These plots of world-wide literature indicate that papers that mention acanthocephalans from fish have progressively increased in number throughout this century and are more abundant in each decade than those on any other group. Papers considering parasites that originate from mammal and bird hosts are also abunhant and their pattern of appearance is less erratic than those for amphibians, reptiles and invertebrates. Notice that for some groups there are decades when we have no record of anything reported. As mentioned in the Materials and Methods, the lag time required to discover publications once they are in base

U.S.S.R.

COUEUTR’~

for

which

Acanthocephalan DISCUSSION

The decrease in numbers of papers published (Fig. 1) during the most recent time period (1985-1990) and to a lesser extent in 1980-1984 is interpreted as the lag time required for discovering this information. There is, of course, the possibility that a real decrease in the number of published papers has occurred; but if true, we believe the magnitude suggested by Fig. 1 is exaggerated. The determination of geographic location of research by using location of publisher is obviously flawed. However, we do not believe it is fatally so. We recognize that authors in developing countries may not have local publishers. Authors under these circumstances would of necessity be required to publish in serials from other countries. Even with these faults the information presented in Fig. 5 suggests regions that are badly understudied. The data on authors (Figs. 2-4) are as expected. Namely, not many investigators regularly study Acanthocephala, and articles that include acanthocephalans have gradually had an increase in numbers of authors. We believe there are many reasons for this. (1) As governments have given money to investigators, those doing the actual work may not be the people receiving the support yet all the names are entered as authors on publications. It may be a case of laboratory directors who neither received the financial support or did the work but whose names were added. (2) People who earlier would have been credited in the acknowledgements are now given authorship. (3) The work may be sufficiently complicated or multifaceted so as to require several investigators. (4) It may be the pressure to publish that causes authors to share publication and thus increase their list of publications. If one assumes that investigators who initiate studies and who have an interest in studying acanthocephalans will appear as first author at some time, then comparison of curves A and C in Fig. 4 suggests to us that the large divergence of these curves is the result of adding authors who have been either adjunctive authors or authors of convenience. Adjunctive authors are those who may have provided critical supplies, essential services, equipment or facilities but had no direct participation in planning or conducting the research. Authors of convenience are those who have done little or nothing to generate the data being presented. Most likely they are important in the political and economic structures within which the primary authors work. Authors may also have a quid pro quo arrangement in order to enlarge their apparent accomplishments. Note that the curves begin marked separation about the time that governments began to accelerate their support for biological sciences.

literature

since 1900

185

If one isolates those people who have published more than 10 papers as first author and examines total authorship of each of these papers, it becomes apparent that those specifically interested in Acanthocephala tend to publish alone or with one other person. Moreover, papers with four to eight authors are more likely to originate outside the United States. Figure 5 shows that there has been an unevenness regarding studies that include acanthocephalan parasites. Some earlier decades show more published papers than more recent ones. However, over the past 90 years the most recent decade has had more activity in all categories than at the turn of the century. The individual patterns are difficult to interpret. If one compares Fig. 6 with the data in Fig. 5, it suggests that interest in Acanthocephala as a group of parasites has not changed much. It certainly does not reflect the large increase in the number of scientists that has occurred this century. Much of the increase that has occurred (Fig. 5) seems to be the results of parasitic surveys in which acanthocephalans are incidental to the researchers’ goals. For example, investigators in the U.S.S.R. have completed hundreds of host and environmental surveys for parasites. Acanthocephala have frequently been only a small part of the discoveries incident to the studies. Work dedicated only to Acanthocephala remains very limited and reflects the few workers specializing in this area (Fig. 5). According to Grissom (1990), approximately 2.34 million scientific papers were published in the U.S. between 1980 and 1989. In the same time frame, world production of papers that even mention acanthocephalans number less than 1000. Those works that exclusively consider this group are much less than one half of the total. One can only conclude the obvious: namely, Acanthocephala are not a popular topic of investigation even among parasitologists. Yearly distribution of acanthocephalan papers according to host (Figs. 6, 7) indicates that research interest in the U.S. runs parallel to that of the rest of the world. The predominance of research reporting the parasites from fish probably reflects the hosts’ wide distribution, ready availability and economic importance as a food source. Both figures support the conclusion that many fewer reports exist for reptiles and amphibians than fish, mammals, and birds. An analysis of the location of publications dealing with these ‘minor’ groups shows the U.S.S.R. to be the primary source. Total reports on primates other than man for the past 90 years number 64, while those that report parasites from people number 56. Note that while these totals are the smallest for any of the groups listed, the distribution pattern does show a marked increase in recent decades. The areas of scientific interest have shifted as equipment and techniques have

D. M. MILLER and T. T. DUNAGAN

186

improved. However, if one accepts that survey studies are largely taxonomic, then this field of work remains the dominant source of publications on Acanthocephala. It probably will remain so since Acanthocephala are of little or no public health interest. Support for their study as an organism doesn’t exist, which in turn, reduces the incentive for parasitologists to select this group of parasites for investigation. Acknowledgements-This work received financial support from the School of Medicine, Southern Illinois University, Carbondale, IL 62901-6512, U.S.A. REFERENCES

AMIN 0. 1985. Classification. In: Siorogy of the Acanfhocephala (Edited by CROMPTOND. W. T. & NICKOL B. B.), pp. 27-72. Cambridge University Press, Cambridge. BREMSER J. G. 1811, Notitia collectionis insignis vermium intestinalium et exhortatio ad commercium litterarium, quo illa perficiatur, et scientiae atque amatoribus reddatur communiter proficua. Naturae scrutatoribus generatim, specialiter autem Enthelminthologis dicata ad Administratione Registris. Caesaraae Musei Historiae Naturalis, Vindobonensis. [Original not seen.] CHANDRA K. J., RAO K. H. & SHYAMASUNDARI K. 1987. On Neoechinorhynchus argentatus n. sp., an acanthocephalan parasite from a marine fish of Waltair. Rivista di Parassitologia 1: 49-52.

CROMPTOND. W. T. & NICKOL B. B. (Eds) 1985. Biology of’the Acanfhocephala. Cambridge University Press, Cambridge. GOLVAN Y. J. 1958. Le phylum Acanthocephala. Premitre note. Sa place dans l’tchelle zoologique. Annales de Parasitologic Humaine et CornpaGe 33: 538-602. GOLVAN Y. J. 1959. Le phylum Acanthocephala. Deuxitme note. La Classe des Eoacanthoctphala (Van Cleave 1936). Annales de Parasitologic Humaine et Cornparke 34: 5-52. GOLVAN Y. J. 1960. Le phylum Acanthocephala. Troisiime note. La classe des Palaeacanthocephala (Meyer 1931) (a suivre). Annales de Parasitologic Humaine et Comparee 35: 224-225. GRISSOM A. 1990. Southern states gain ground in producing science papers. The Scientist 4: 20. LOHE M. 1905. Geschichte und Ergebnisse der Echinorhynthen-Forschung bis auf Westrumb (I 82 1). Zoologische Annalen 1: 139-353. MEYER A. 1932. Acanthocephala. In: Dr. H. G. Bronn’s Klassen und Ordungen des Tier-Reichs, Band 4, Abteilung 2, Lief. 1. Akademische Verlagsgesellschaft. Leipzig. PETROCHENKOV. I. 1956. Acanthocephala qf Domestic and Wild Animals, Vol. 2. Moscow Izdatel’stvo Akademiya Nauk S.S.S.R. [Israel Program for Scientific Translation, 1971.1 REDI F. 1684. Osservazioni di Francesco Redi intorno agli animali viventi the si trovano negli animali viventi (Academia della Crusca). P. Matini, Firenze. [Original not seen.] YAMAGU~I S. 1963. Acanthocephala. In: Systema Helminthum, Vol. 5. Interscience Publishers, New York.