Although hemorrhagic fevers (HF) have been extensively treated in scientific literature of the U.S.S.R., these diseases were of limited concern to Soviet health authorities until 1965 when a regulation to make them reportable was introduced. Our discussions with medical and other scientific authorities suggested that HF incidence is higher and exposure risk is much greater than we had anticipated on the basis of official reports; furthermore, it seemed that the number and variety of recognized natural foci are on the increase.
Hemorrhagic fever with renal syndrome (HFRS) is by far the most important epidemic HF in the Soviet Union today. Omsk HF (OHF) has been of little recent importance, except among workers in the muskrat for industry. Crimean type HF (CTHF) has been absent from the Crimea for many years; a very similar epidemic disease presumably caused by the same virus now occurs in the Volga and Don delta regions. Central Asian HF (CAHF) was said to be practically non-existent at present, possibly because of environmental modifications by extensive irrigation systems.
Appraisal of the HF classification widely accepted in the U.S.S.R. exposed many lacunae in clinical, virological, epidemiological, ecological, and zoological knowledge of Soviet HF entities (Table 2). This classification should therefore be considered a tenuous synthesis of certain demonstrated facts and speculations based on field observation. An especially important problem is whether HFRS, with its high morbidity and mortality in the Far East, is the same etiologic entity as HFRS in the European U.S.S.R., where it is a relatively mild disease (this is of particular interest because of the assumed relationship of Korean HF and HFRS). The question will not be definitely answered until etiologic agents have been isolated and characterized.
At this time OHF is the only characterized HF syndrome for which an undisputed etiological agent is available. The status of etiologic agents for other HF entities continues to be unsettled. In 1964 the GON virus strain was isolated from the blood of a patient suffering from what was clinically diagnosed as CTHF; forming plaques in its 19th passage in cercopithecus monkey kidney cell cultures, this strain is currently the most promising agent for CTHF, although its role has not been yet definitively established. Repeated and complicated virological attempts to isolate the etiological agent of CAHF have proved fruitless. Isolation of an HFRS agent from human volunteers was reported in the early literature, but extensive attempts to recover viruses from specimens collected during recent outbreaks have failed.
The recognized inadequacy of investigations on HF pathogenesis and pathophysiology elsewhere in the world appears to be also true for the U.S.S.R.; this includes even OHF, the etiology of which was established 20 years ago. Zoological and ecological studies on the muskrat and vole (Omsk) and on rooks and domestic mammals (Volga and Don deltas) are examples of field investigations that need to be multiplied and expanded to elucidate the HF problems. Owing to their biological and microbiological implications, ticks, especially of the genus Hyalomma, require more extensive field surveys and collections to allow further bionomic and systematic assessment.
The Delegation was exceptionally well received in the U.S.S.R. and, in retrospect, the mission was remarkably successful. Unfortunately, due to conditions beyond our control, it was not possible to assess fully the data on HFRS and OHF. What was learned emphasised the desirability of a more deliberate examination of these problems in the recognized foci and regional laboratories at Ufa, Omsk, Khabarovsk, and Vladivostock, even though such undertaking would require another month. Best use was made, however, of available opportunities to examine the natural foci and investigations in progress on CTHF in the Rostov and Astrakhan regions of the Russian republic and on CAHF in the Kazakh and Uzbek republics of Central Asia.
Rockefeller Foundation, Yale Arbovirus Research Unit, New Haven, Connecticut.
United States Naval Medical Research Unit Number Three, Cairo, Egypt, U.A.R.
Middle America Research Unit, Canal Zone, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Public Health Service, U. S. Department of Health, Education and Welfare.
Division of Biologics Standards, National Institutes of Health, Public Health Service, U. S. Department of Health, Education, and Welfare, Bethesda, Maryland.
National Institute of Allergy and Infectious Diseases, National Institutes of Health, Public Health Service, U. S. Department of Health, Education and Welfare, Bethesda, Maryland.
Communicable Disease Center, Atlanta, Georgia, Public Health Service, U. S. Department of Health, Education and Welfare.