A widespread outbreak of tularemia in Sweden in 2000 was investigated in a case-control study in which 270 reported cases of tularemia were compared with 438 controls. The outbreak affected parts of Sweden where tularemia had hitherto been rare, and these "emergent" areas were compared with the disease-endemic areas. Multivariate regression analysis showed mosquito bites to be the main risk factor, with an odds ratio (OR) of 8.8. Other risk factors were owning a cat (OR 2.5) and farm work (OR 3.2). Farming was a risk factor only in the disease-endemic area. Swollen lymph nodes and wound infections were more common in the emergent area, while pneumonia was more common in the disease-endemic area. Mosquito bites appear to be important in transmission of tularemia. The association between cat ownership and disease merits further investigation.
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.
Tularemia was diagnosed in 57 patients during an outbreak in central Norway in 1984 and 1985. Clinical categories of the disease showed seasonal variations. A bacterial microagglutination test and an enzyme-linked immunosorbent assay (ELISA) with class-specific antibodies against Francisella tularensis outer membrane (OM) antigens were evaluated for the early diagnosis of tularemia. ELISA with immunoglobulin G (IgG), IgA, or IgM antibodies and the microagglutination test differed only marginally in diagnostic sensitivity. The OM preparation harbored F. tularensis agglutinogens and contained a variety of proteins, several of which functioned as immunogens in tularemia patients, as shown by Western blotting (immunoblotting). All 12 patients tested produced antibodies against a 43,000-molecular-weight OM protein. Individual variation was noted with regard to antibody response against other OM antigens. The OM is a suitable antigen preparation in ELISA for the diagnosis of tularemia and, presumably, contains antigens important in the immunobiology of tularemia.
In a tularemia epidemic during 1982 in northern Finland, 53 patients showed no peripheral portal of entry for infection or associated lymphadenopathy. Respiratory symptoms were observed in 72% of the patients. 26/38 cases had abnormal chest films. Hilar adenopathy was the most common finding (36%). Four patients did not receive antibiotics; 43 received tetracyclines, 5 streptomycin and 1 cefuroxime and amoxycillin. All patients recovered. 50 patients acquired the infection during common farming activities, such as making fresh hay with a hay-cutter, handling dry hay, threshing, etc. Thus, airborne transmission may be an important source of infection in normal farming activities in endemic areas of tularemia.
Tularaemia has mainly been a sporadic disease in Norway. In 2011, 180 persons (3.7 per 100,000 population) were diagnosed with tularaemia. This article describes the epidemiological and clinical features of tularaemia cases during a year with exceptionally high tularaemia incidence. Data from the national reference laboratory for tularaemia combined with epidemiological data from the Norwegian Surveillance System for Communicable Diseases (MSIS) were used. The incidence of tularaemia varied greatly between counties, but almost every county was involved. The majority (77.8 %) of the cases were diagnosed during the autumn and winter months. The geographic distribution also showed seasonal patterns. Overall, oropharyngeal tularaemia (41.1 %) was the most common clinical presentation, followed by glandular (14.4 %), typhoidal (14.4 %), respiratory (13.3 %) and ulceroglandular (12.8 %) tularaemia. From January to April, oropharyngeal tularaemia dominated, from May to September, ulceroglandular tularaemia was most common, whereas from October to December, there was an almost even distribution between several clinical forms of tularaemia. Eighty-five (47.2 %) of all tularaemia cases were admitted to, or seen as outpatients in, hospitals. An unexpectedly high number (3.9 %) of the patients had positive blood culture with Francisella tularensis. The clinical manifestations of tularaemia in Norway in 2011 were diverse, and changing throughout the year. Classification was sometimes difficult due to uncharacteristic symptoms and unknown mode of transmission. In rodent years, tularaemia is an important differential diagnosis to keep in mind at all times of the year for a variety of clinical symptoms.
The investigation of the epidemic outbreak of tularemia morbidity among the population of Vyaz'ma, was carried out. In this investigation the disease was shown to be transmitted by the water route due to contamination of water in the local water mains as the result of serious violations of the rules of using water supply systems. In the process of the investigation of this outbreak a natural focus of tularemia, not registered heretofore, was discovered. The work emphasizes the inadmissibility of deviations from the generally accepted tactics of tularemia control, consisting of a complex of prophylactic measures, such as the vaccination of the population, deratization and disinfection, the examination of the foci of infection, state sanitary surveillance, especially with regard to the sources of water supply and the quality of water preparation, raising the level of professional skills of the personnel and sanitary education.