Exploration of natural foci of tularemia and plague in Armenia using the serological examination of bird droppings and excrements of predatory mammals]

Forty strains of tularemia and 619 of plague microbes were isolated in 1974 in bacteriological examination of natural plague and tularemia foci from a great number of small mammals and their ectoparasites. At the same time in serological examination (in the antibody neutralization test) of bird pellets, 52 mummified cadavers, and 34 excretion samples of mammalian beasts of prey collected in Armenia (its central and North-Western part) in 1973 the antigen of tularemia microbe was revealed in 73, 8, and 3, and of plagye--in 42, 5, and 1 cases, respectively. In one of the sites examined the number of positive findings failed to exceed 10--17%, this indicating a low intensity of the epizootic in the majority of the places. Judging by the mean titres of the serological test, which varied from 1:12 to 1:1428 in examination for tularemia and from 1:12 to 1428 in examination for plague, it was possible to detect both epizootics coursing during the examination, and those which occurred several monts ago. Tularemia and plague foci were not infrequently present at the same territories, and these diseases could involve the same individual animals of Microtus arvalis (Pall.). The data obtained pointed to the greater effectiveness of examination of bird's pellets and excretions of mammalian beasts of prey for the reconnaisance investigation of the natural foci of plague and tularemia in comparison with the bacteriological methods applied usually.     

Results of an epidemiological study of familial foci of salmonellosis in the Western Urals

The study of 449 family foci of salmonellosis demonstrated the possibility of detecting cases of salmonellosis, not diagnosed by clinical and bacteriological methods, in the passive hemagglutination test. Such undetected Salmonella carriers, not observing the rules of personal hygiene, contributed to the contamination of household articles, foodstuffs and the environment. The formation of the family foci of salmonellosis was facilitated by the belated detection and hospitalization of salmonelloses cases, as well as by the inadequate observance of the rules for infant care and feeding.     

Results of a controlled epidemiological trial of the application of placental gamma globulin in foci of meningococcal infection]

Controlled epidemiological trial was applied to the study of the use of placental gamma-globulin for prophylaxis of generalized forms of meningococcus infection in the foci (creches and kindergartens). A group of the vaccinated children (16 140) and control group (16 080) were the same age and sex. Gamma-globulin was administered in a dose of 3 ml to every other child attending creches and kindergartens not later than the 10th day after the patient's isolation. It was shown that the efficacy coefficient of gamma-globulin in the foci of meningococcus infection constituted 68% (the efficacy index was 3.2) for one month after the administration.     

Experimental study of the infecting ability of the flea Coptopsylla lamellifer rostrata in the Kyzylkum natural focus of plague

Experimental infecting of the fleas Coptopsylla lamellifer rostrata by plague was carried out. The fleas were infected by feeding through biomembrane (skin of a white mouse) with a mixture of defibrinated blood of guinea-pig and plague microbes. Under concentration 2-3 milliard of the microbes in 1 millilitre, from 60 to 100% of the fleas were infected. Forming of the block of proventriculus was observed in 9-13 day. Mean percent of blocking for all experiments was less than 1%. Maximal rate of blocking (2.8%) was observed in the experiment under everyday 3-hour feeding. After planting of the fleas with blocks on great gerbil (2 fleas on one gerbil) 20% of the gerbils were infected. The conclusion had been made that C. lamellifer rostrata has only insignificant effectiveness as a vector of plague agent in Kyzylkum. Probably it is caused by some specific features of this subspecies.     

Hepatitis A foci in children's collectives studied by using clinico-biochemical, virological and serological diagnostic methods

In 4 foci of hepatitis A (HA) at children's institutions in Moscow 218 children and 30 staff members were examined. Simultaneously with clinico-biochemical studies, specific IgM and IgG in the blood and hepatitis A virus (HAV) antigen in feces were determined by radioimmunoassay. Different forms of HA were detected in 29.1% of children in kindergartens, 19.4% of school children and 3.3% of adults, which was due to great differences in the size of the immune stratum among them (IgG to HAV was detected in 8-10% of children aged 3-6 years and in 83% of adults). In 2/3 of children with HA in the foci the disease was not accompanied by jaundice, 1/5 of them having the inapparent form of this infection. In 45% of the patients HAV antigen was detected in feces, irrespective of the form of HA, 5-14 days before the appearance of hyperfermentemia, and in 2/3 of them this antigen was also detected during the first 6 days after that. Simultaneously with an increase in aminotransferase activity, all of the HA patients showed the presence of specific IgM in their blood.     

International and national aspects of epidemiological plague surveillance in the USSR.

General principles and organizational forms of epidemiological surveillance of plague in the USSR both in seaports andin natural foci are discussed. On the basis of the analysis of the authors' experience over many years and taking into consideration literary data, the authors recommend a minimum, but in their opinion effective amount of a successful realization of these recommendations, it is expedient to establish a special team (or teams) consisting of 10-12 members.     

Activation of natural tularemia foci of the field-meadow and steppe types on the territory of Tula Province 1977-1978

Natural tularemia foci of the meadow and steppe type are extremely stable and become active in those years when the most favourable living conditions for rodents appear. For the first time during the last 30 years a great increase in the number of common voles, accompanied by widely spread epizooty covering the whole territory of the Tula region, was observed. House mice, common field mice, harvest mice and black rats were also involved in this epizooty and 235 tularemia patients with all clinical forms of the disease were registered, the pulmonary form of the disease being prevalent. The cases of the disease were observed among both urban and rural population. In spite of a high morbidity rate, no cases of group infection were registered in domestic conditions and among agricultural workers due to the existence of the numerous immune layer among the population. The formation of this layer resulted from planned vaccinal prophylaxis covering, on the average, 86.3% of the rural population of the region.     

Broader investigation into the external environment of the specific antigen of the infectious agent in epizootiological observation and study of the structure of natural foci of plague.

The possibilities of detection of the infectious agent in natural foci of plague can be expanded to some extent by using the method of search for the specific FI capsular antigen of the plague microbe in such objects of the external environment which have not yet been subjected to laboratory analysis and serological analysis in particular. Such objects include soil from the burrow and the substrate of the nest of the rodent as well as the fleas of rodents and regurgitations of birds of prey.The effectivity and suitability of examination of these objects using immuno-adsorption reactions with standard erythrocyte diagnostics (passive haemagglutination reaction, antibody neutralization reaction) were demonstrated experimentally and confirmed under field conditions in various geographical and ecological zones of the Caucasus. Thus in 1971, an earlier unknown natural focus of plague was found in the Mount Elbrus massif by means of serological analysis of the substrate of the nest and of the soil from the burrows of rodents. It can be expected that broadened serological search for the FI antigen of plague will prove useful in the study of the structure of natural foci of plague, in the reconnaissance or retrospective investigation of poorly explored territories and in the solution of some questions concerning the epizootiology of plague, such as the survival of the infectious agent in the inter-epizootic period, telluric plague, etc.     

Issues in the epidemiological investigation of dry mouth

Despite decades of research, much remains unanswered about the epidemiology of dry mouth. This review aims to provide an overview of the condition's epidemiology and the issues to consider when planning an epidemiological study of dry mouth. The latter can be broadly grouped into: study design; sampling and statistical power considerations; the measurement of dry mouth; and the selection, nature and measurement of relevant exposure measures, including medications and potential confounding variables. Each of these is discussed, in order to provide guidance for prospective researchers based on experience with past research. Finally, an agenda for further epidemiological research into dry mouth is proposed.     

Results of using the ELISA method in studying tick-borne encephalitis and rabies

The results of using the indirect variant of ELISA for the study of serum samples from humans and white mice for the presence of antibodies to tick-borne encephalitis virus and rabies virus are presented. The high sensitivity and specificity of this method have been confirmed.     

Evaluation of three serological tests for the detection of human plague in northeast Brazil.

The passive haemagglutination (PHA) test, enzyme-linked immunosorbent assay (ELISA) and the dot enzyme-immunosorbent assay (DOT-ELISA) were used to detect the levels of IgG antibodies against the Fraction 1 (F1) antigen of Yersinia pestis in sera of plague-infected patients from Northeast Brazil. Twenty three selected PHA-positive sera of subjects with bacteriological confirmation of plague were also positive in the DOT-ELISA but only 19 were detected by the conventional ELISA technique. Another group of 186 serum samples from subjects diagnosed as plague-infected by clinical and epidemiological parameters, but PHA-negative, were screened with DOT-ELISA and 11 gave positive results. The specificity of the assays on the serological detection of plague was confirmed in inhibition tests using purified F1 antigen. These results suggest that DOT-ELISA can be an useful, simple and more sensitive alternative for the serodiagnosis of plague in Northeast Brazil.