Prologue

This section describes the materials and methods used in the preparation of this report. The viruses selected for study were determined by reviewing the major textbooks concerned with the diseases of domestic animals (1,2,4–8,10,11,14,15). The viruses chosen represent either zoonoses or those most pathogenic for domesticated animals. As a background, brief synopses of the pertinent features of over 90 separate viruses were prepared so that a more critical appraisal of the literature would be possible.

In April 1981 an on-line computer assisted information retrieval system (Dialog File 50) was utilized to provide the abstracts on articles dealing with geography, diagnosis, and epidemiology of most of the 90 viruses chosen for study. The data base searched was that of the Commonwealth Agricultural Bureaux (CAB).

The search was extended as far back as 1972. During the same time the USDA provided abstracts of federally funded projects involving the study of many of the viruses. The investigators and the publications generated by those projects were listed as well. This material is available to USDA personnel and faculty members of land-grant colleges in the United States. It is called Current Research Information System (CRIS). The Smithsonian Institute produced a similar document, i.e., “The geographical distribution of animal viral diseases with emphasis on: endemic patterns, epidemiology, distribution, surveillance of diseases, antibody detection and serum surveys,” under their Smithsonian Scientific Information Exchange, Inc. (SSIE).

The Dialog File 50 computer-assisted search was a free text search. That is, when the computer does not find the critical word in the title, the key word section or the identifier section, it will screen every word of the abstract before rejecting a particular abstract. This thoroughness (which could not be duplicated utilizing several people over a significant time period) resulted in some liabilities. For instance, Peste des petits ruminants is known in the vernacular as “Kata” in West Africa. In the computer printouts for that section several abstracts were received that dealt with grapevines or diverse materials of Polish origin. In both cases the word Kata appeared in the title, key word, identifier section, or the body of the abstract. Kata is the genus name of a plant and must be a Polish word of undetermined translation.

During the Spring and early summer of 1981 the Biological Abstracts, Index Medicus, Index Veterinarius, the Veterinary Bulletin, and the Animal Disease Occurrence (ADO) were searched for appropriate articles, primarily for the period from January 1977 up to the most recent issue.

Using the 1978 Animal Health Yearbook and information derived from reading selected articles, the author prepared simple maps delineating the areas where the respective viruses had been reported. These maps were sent to recognized authorities on the specific viruses and their comments solicited. These authorities were identified from assessment of CRIS and SSIE and from determining the authors of the articles most relevant to the objectives of this project (geographical distribution of the viruses).

A synopsis of the important facts regarding a particular virus was included with the map (in most cases) along with a sheet defining the categories of information used in the synopsis. In a cover letter these authorities were invited to participate in the project as reviewers or consultants.

This packet of material was sent to from one to six people per virus covered. Approximately 150 packets were sent during July 1981. About 80% of those contacted responded and agreed to provide input or review the information on the viruses. The overwhelming majority expressed enthusiasm and intense interest in the project. Those who declined to participate suggested alternates who might be contacted.

During the fall of 1981 and the winter of 1981–1982 the responses from the various experts were received and collated for the same virus. This material was combined with a constant literature update provided by the National Agricultural Library via Current Awareness Literature Service (CALS). This service screens pertinent articles and abstracts utilizing Biological Abstract, CAB, and AGRICOLA as data bases. For each virus the latest copies of Index Veterinarus and ADO were also reviewed.

A new map and information sheet (synopsis) were sent to all reviewers who responded for additional scrutiny and approval. Again the process was repeated. Individuals were, in general, very predictable and consistent. Those who were late in their initial response were late in their second. Those who were thorough in their first tended to be the same in the second, which of course meant newly suggested changes had to be considered.

The literature review for the synopses effectively ended in July 1982. For the maps there was a constant update until the fall of 1982 so that as many documented areas as possible could be included.

During 1982 access to several excellent publications became available (3,9,10,13,16). Many of these proved to be very helpful in that they contained good reviews of the geographical distribution of many viruses (3,9,16).

The maps were prepared using the following guidelines. The straight horizontal line shading represents areas for which there are well-documented citations available. In most cases well-documented means a published article of isolation of the virus or demonstration of specific antigens in tissue sections or serum antibodies. In some cases in which the reviewer was a recognized expert, well-documented may mean a written communication from his or her laboratory based on unpublished work.

For those viruses that were said to have a worldwide distribution, information from the 1979 and 1980 AHYs was used as well. Countries reporting the presence of a particular virus were stippled. Well-documented evidence superseded the AHY. Therefore, the countries represented with horizontally straight line shading may or may not have been listed as positive in the AHY.

Those areas for which there were no documented reports, but were suspected to have the virus for one reason or another, were represented by horizontal wavy line shading. An explanation of the criteria used for “suspected” is presented in Appendix B separately for those viruses involved.

The blank areas indicate that no documentation could be found in the literature by the author or the reviewers. If the readers know of such documentation for any of those countries for a particular virus, please advise the author of that fact. In some cases the blank areas may actually have documented reports demonstrating negative serum surveys. These situations are evident by consulting Section C (Areas free of the virus) in the synopsis opposite the map.

When viewing the individual maps, if there is a question regarding the identification of a certain country, Appendix A contains the key to establish the names of all the countries of the world that are discernible.

Appendix B contains the pertinent literature dealing with each viral distribution. To conserve space, if available, the best review article that cites the largest numbers of countries (with documentation) is presented first. Shaded countries not covered in the review article are listed individually following the review article citation. The country name is boldfaced and is followed by the documentation in brackets or parentheses. Therefore, by consulting Appendix B the reader should be able to find the specific reference that was used as a basis for shading the individual countries

For certain viruses that have a recognized worldwide distribution the specific citations are not presented in Appendix B, because of obvious space limitations. In these cases the AHYs for 1979 and 1980 were used as a guide in preparing the maps. In some of these cases an exhaustive search for documentation was not even attempted.

Once all the completed materials were assembled, the individual sections were mailed to the reviewers and consultants for a final appraisal. Approximately 20% of these were returned with additional comments and suggestions. The newer references were inserted in the synopses by addition of the small letter “a” immediately following the number. In some cases the more recent references may be found in Appendix B.

The author spent one week during July 1982 at the National Agricultural Library (NAL) in Beltsville and one week at the offices of the Emergency Program of APHIS in Hyattsville, Maryland, searching and reading references unavailable in Georgia.

It should be recognized that it is virtually impossible for a single individual or even a group of people to completely cover all the world’s literature for a specific disease. If a reader is aware of a pertinent reference obviously overlooked, he or she should so advise the author.

The interpretation of the literature is another matter. In a very few cases, all the reviewers did not agree. The policy was adopted that as long as there was a published account in a reputable journal using an established diagnostic technique, then the citation would be sustained. There were other dilemmas with regard to extrapolation of the published materials to the maps. For instance, the national reports may...