The 2000 tularemia outbreak: a case-control study of risk factors in disease-endemic and emergent areas, Sweden. (Research).A widespread outbreak of tularemia tularemia (t  lərē`mēə) or rabbit fever, acute, infectious disease caused by Francisella tularensis (Pasteurella tularensis). in Sweden in 2000 was
investigated in a case-control study case-control study,n an investigation employing an epidemiologic approach in which previously existing incidents of a medical condition are used in lieu of gathering new information from a randomized population. 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 The use of multiple variables in a forecasting model. regression analysis In statistics, a mathematical method of modeling the relationships among three or more variables. It is used to predict the value of one variable given the values of the others. For example, a model might estimate sales based on age and gender. 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 Lymph nodes Small, bean-shaped masses of tissue scattered along the lymphatic system that act as filters and immune monitors, removing fluids, bacteria, or cancer cells that travel through the lymph system. 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. ********** Tularemia is caused by Francisella tularensis Francisella tu·la·ren·sis n. A bacterium of the genus Francisella that causes tularemia in humans. , a fastidious fas·tid·i·ous adj. 1. Possessing or displaying careful, meticulous attention to detail. 2. Difficult to please; exacting. 3. Having complex nutritional requirements. Used of microorganisms. , gram-negative rod. F. tularensis subsp. tularensis, or type A, occurs mainly in North America North America, third largest continent (1990 est. pop. 365,000,000), c.9,400,000 sq mi (24,346,000 sq km), the northern of the two continents of the Western Hemisphere. and is more virulent vir·u·lent adj. 1. Extremely infectious, malignant, or poisonous. Used of a disease or toxin. 2. Capable of causing disease by breaking down protective mechanisms of the host. Used of a pathogen. 3. than F. tularensis subsp, holarctica, or type B, which occurs throughout the Northern Hemisphere. Type A is usually transmitted to humans by tick bites or contact with rabbits; type B is associated with water and animals living near water, and its transmission seems more complex (1-6). In Sweden, >6,000 human cases of tularemia have been reported since the disease was first described in 1931. However, incidence varies greatly from year to year, ranging from a few cases in some years to >2,700 cases in 1967. The ulceroglandular form of tularemia is by far the most common in Sweden, except for an outbreak in the winter of 1966-67, when a large proportion of pulmonary tularemia cases occurred in farmers who processed hay contaminated contaminated, v 1. made radioactive by the addition of small quantities of radioactive material. 2. made contaminated by adding infective or radiographic materials. 3. an infective surface or object. by dead, infected voles (7). Apart from this outbreak, most cases in Sweden have occurred in late summer and early autumn and are thought to have been transmitted by mosquitoes (8,9). Most cases occur within a relatively small area in the central part of Sweden, with only sporadic cases in other areas. In recent years, however, the disease seems to have spread to areas south of the disease-endemic area. This shift was apparent in the 2000 outbreak, when 187 (40%) of 464 cases were reported to have been transmitted south of the disease-endemic area. The reason for this spread is unknown. We studied the risk factors for acquiring tularemia in Sweden, as well as the prevalence of the risk factors in the disease-endemic and the new, "emergent" areas during the outbreak of 2000. We performed a matched case-control study, using a modified questionnaire designed by a Finnish group that was studying a concurrent tularemia outbreak in Finland. Methods Identification of Cases and Controls Tularemia has been a notifiable disease no·ti·fi·a·ble disease n. A disease that must be reported to public health authorities at the time it is diagnosed because it is potentially dangerous to human or animal health. Also called reportable disease. under the Communicable Diseases communicable diseases, illnesses caused by microorganisms and transmitted from an infected person or animal to another person or animal. Some diseases are passed on by direct or indirect contact with infected persons or with their excretions. Act in Sweden since 1968. Physicians who diagnose a case, either clinically or by microbiologic means, report to the county medical officer and the Swedish Institute The Swedish Institute (Svenska Institutet, SI) is a Swedish government agency with the responsibility to spread information about Sweden abroad, to promote Swedish interests, and to organise exchanges with other countries in different areas of public life, in particular in for Infectious Disease Infectious disease A pathological condition spread among biological species. Infectious diseases, although varied in their effects, are always associated with viruses, bacteria, fungi, protozoa, multicellular parasites and aberrant proteins known as prions. Control (SMI (1) (Storage Management Initiative) The initiative developed by the SNIA in 2003 to create a single standard interface for storage management technologies used by multiple vendors and networking communities. ). Cases were defined as tularemia in all persons ages [greater than or equal to] 18 whose illness was reported to SMI from August 1 (week number 31) to November 21, 2000 (week number 47) and who resided in any of seven counties in central Sweden, representing both disease-endemic and emergent areas (Figure 1). The cases from these seven counties represented 60% of all cases reported in Sweden during the study period; the rest were sporadic cases from other areas or infection acquired abroad (Figure 2). [FIGURE 1-2 OMITTED] Controls matched for age, sex, and place of residence were drawn from the computerized Swedish National Population Register, in which the name, date of birth, personal identifying number, and address of all citizens and residents are stored. Matching for place of residence was done on the first three digits of the five-digit postal code Noun 1. postal code - a code of letters and digits added to a postal address to aid in the sorting of mail postcode, ZIP code, ZIP code - a coding system used for transmitting messages requiring brevity or secrecy , since this three-digit area corresponds to a small town, village, or municipality MUNICIPALITY. The body of officers, taken collectively, belonging to a city, who are appointed to manage its affairs and defend its interests. . We chose controls whose date of birth was as close as possible to that of the patient, with a difference [less than or equal to] 12 months. Two controls were selected for each case. A questionnaire was mailed to the two controls; if neither responded within 2 weeks, a third control was chosen in the same way. If a control reported having had fever during the period of investigation and no diagnosis other than tularemia was made, he or she was excluded from the analysis. On the standardized questionnaire mailed to both case-patients and controls were questions on whether they had had an elevated temperature during the 4-week period 2 weeks before and 2 weeks after onset of symptoms in the patient. Additional data were collected on symptoms, medication, and referral to hospital. Participants were also asked about number of persons in the household and symptoms in other household members during the defined period. The second part of the questionnaire contained questions on exposure to presumed risk factors for acquiring tularemia during the 4-week period preceding the reported day of onset of illness. The following exposures were recorded: owning cats, dogs, or other animals; visiting golf courses and forests; participating in farming procedures of different kinds; having contact with dead animals, with or without wearing gloves; visiting or swimming in lakes or rivers; drinking water drinking water supply of water available to animals for drinking supplied via nipples, in troughs, dams, ponds and larger natural water sources; an insufficient supply leads to dehydration; it can be the source of infection, e.g. leptospirosis, salmonellosis, or of poisoning, e.g. from lakes or wells; picking berries or mushrooms; and being bitten by mosquitoes, mites, ticks, deer flies deer fly see chrysops. , or other insects. Respondents were also asked if they had used insect repellents insect repellent, substance applied to the skin in order to provide protection against biting insects, primarily mosquitoes, ticks, chiggers, fleas, and certain flies. . Visits to areas other than place of residence during the defined period of exposure were also recorded. In the 2000 epidemic, cases occurred in places where tularemia had rarely been reported. To evaluate whether this spread was connected to any new risk factors, the seven counties in the study area were divided into three categories (Figure 1): the disease-endemic area, County of Gavleborg, from which cases were reported every year during the 1990s; the border area, County of Dalarna, where occasional cases and small outbreaks have been reported during the last decade; and the emergent area, which consists of the counties of Stockholm, Sodermanland, Vastmanland, Varmland, and Orebro, from which only one or two cases have been reported in isolated years during the 1990s, but where a large part of the cases occurred in 2000. This division was done by actual place of exposure, as could be judged by routine notifications from the period 1990-99, and not by place of residence. The endemic group consisted of 84 case-patients and 159 controls, a total of 243 persons, while 300 persons were in the emergent group (105 case-patients and 195 controls). We chose to analyze these two groups separately for symptoms and exposures as above, but to improve the discrimination between the old and new tularemia areas, we excluded the third group, consisting of 29 case-patients and 60 controls from the border area, from this part of the analysis. Statistics A matched univariate analysis, with calculation of odds ratios (OR) and 95% confidence intervals confidence interval, n a statistical device used to determine the range within which an acceptable datum would fall. Confidence intervals are usually expressed in percentages, typically 95% or 99%. (CI) by the Mantel-Haenszel method, was done in EpiInfo 6.04 (Centers for Disease Control, Atlanta, Georgia) and the Stata program (Stata Corp., College Station, Texas College Station is a city in Brazos County, Texas, situated in Central Texas. It is located in the heart of the Brazos Valley. The city is located within the most populated region of Texas, near to three of the 10 largest cities in the United States - Houston, Dallas, and San ). Multivariable analysis was done by conditional logistic regression In statistics, logistic regression is a regression model for binomially distributed response/dependent variables. It is useful for modeling the probability of an event occurring as a function of other factors. for matched data in the Stata program. Results Two hundred seventy cases fulfilled the above criteria. All the case-patients were ill during the summer or in the early autumn. No cases were reported during 2000 before the start of the study period on August 1. Of cases, 86% were confirmed with serologic testing serologic test Lab medicine A test that measures components–eg, antibodies, complement, and reactions–eg, complement fixation, agglutination, precipitation, etc, that reflect immune status, especially antibody titers. Cf Seroconversion. or culture. The questionnaire was sent to all 270 case-patients and 670 controls. Replies were received from 243 (90%) of 270 case-patients and 438 (65%) of 670 controls, for a total of 681 (72%) of 940. Twenty-five cases and 21 controls were excluded because of confusion about the time periods used in the questionnaires. One control was excluded because of a documented episode of tularemia, one control was excluded because of an episode of febrile febrile /feb·rile/ (feb´ril) pertaining to or characterized by fever. feb·rile adj. Of, relating to, or characterized by fever; feverish. illness that could have been tularemia, and another control was excluded because the wrong person filled out the questionnaire. Thus, 218 cases and 414 controls, from which 202 matched pairs or triplets could be arranged, remained for further analysis. With regard to symptoms, 198 (95%) of 209 case-patients reported having had a fever during their episode of tularemia. Of these, 147 (86%) of 171 reported swollen lymph nodes, 143 (79%) of 180 wound infection, 26 (20%) of 132 sore throat Sore Throat Definition Sore throat, also called pharyngitis, is a painful inflammation of the mucous membranes lining the pharynx. It is a symptom of many conditions, but most often is associated with colds or influenza. , 39 (28%) of 138 cough, and 10 (5.2 %) of 193 pneumonia diagnosed by a physician. As a measure of severity of disease, 34 (16%) of 212 were hospitalized. The median duration of hospitalization hospitalization /hos·pi·tal·iza·tion/ (hos?pi-t'l-i-za´shun) 1. the placing of a patient in a hospital for treatment. 2. the term of confinement in a hospital. was 4 days. No deaths were reported. The matched univariate analysis (Table 1) gave statistically significant results for the following exposures: owning a cat, farming, visiting wooded areas, and being bitten by mosquitoes. After multivariate analysis multivariate analysis, n a statistical approach used to evaluate multiple variables. multivariate analysis, n a set of techniques used when variation in several variables has to be studied simultaneously. , owning a cat, farming, and being bitten by mosquitoes remained as independent risk factors. Sex and age distributions were similar in the endemic and emergent groups. Having had swollen lymph nodes (47 [78%] of 60 vs. 85 [96%] of 89 [p=0.001]) or a wound infection (48 [72%] of 67 vs. 78 [89%] of 88 [p=0.007]) was significantly more common in the emergent group, while having had pneumonia (7 [9.3%] of 75 vs. 1 [1.1%] of 94 [p=0.02]), was significantly more common in the endemic group. The matched univariate analysis in the endemic group showed significant results for the following exposures: owning a cat, farming, and being bitten by mosquitoes. In the emergent group, being bitten by mosquitoes and visiting woods or forests appeared as risk factors (Table 2). After multivariate analysis, owning a cat and being bitten by mosquitoes were shown to be independent risk factors for acquiring tularemia in both groups, while farming was a risk factor only in the endemic group. Discussion We report results from a study of a tularemia outbreak in Sweden, with a spread of the disease into new geographic areas. The use of a mailed questionnaire with matched controls matched study, matched control a comparison between groups in which each subject animal is matched by a comparable animal in terms of age and all other measurable parameters. Called also matched or paired control. from the Population Register had a high response rate even among controls. Frequency of reported symptoms from case-patients are consistent with earlier data, showing ulceroglandular tularemia to be the dominant form in Sweden (10). A substantial part of the case-patients (16%) were hospitalized. Pulmonary tularemia was seen in only 10 (5.2%) of 193 cases, in contrast to the outbreak in the winter of 1966-67, when 11% had pneumonia symptoms. Statistically significant independent associations were found between acquiring tularemia and the following exposures: being bitten by a mosquito, doing farm work, and owning a cat. The results for mosquito bites could have been influenced by recall bias, since this transmission route has always been thought to be the most common in Sweden and many patients might thus have been told by their physician that mosquitoes caused the infection. However, the predominance pre·dom·i·nance also pre·dom·i·nan·cy n. The state or quality of being predominant; preponderance. Noun 1. predominance - the state of being predominant over others predomination, prepotency of the ulceroglandular form of tularemia and the seasonal variation of the disease support the theory that mosquito bites are the major route of transmission in Sweden. Farming has not been connected with tularemia in Sweden since the outbreak in 1966-67. However, about pulmonary tularemia was reported among farmers in Finland in 1982 (11). In spite of detailed questions about different farming activities, no specific practice could be implicated im·pli·cate tr.v. im·pli·cat·ed, im·pli·cat·ing, im·pli·cates 1. To involve or connect intimately or incriminatingly: evidence that implicates others in the plot. 2. in our study, perhaps because relatively few of the persons studied were involved in farming. Transmission of tularemia from cat to humans, mainly caused by F. tularensis subsp, tularensis, but also by F. tularensis subsp, holarctica, has been described from North America, from both sick and healthy cats, and with or without the patient's being bitten by the cat (12-17). Furthermore, Scheel et al. reported a case of tularemia in a veterinary surgeon in Norway who cut himself while spaying spaying: see castration. a cat (18). The increased risk in cat owners could be due to direct transmission from infected cats or exposure to dead animals brought home by the cat. We found no increased exposure to dead animals among case-patients who were cat owners. The connection between cats and tularemia needs to be studied further, and a seroepidemiologic study of cats in affected areas would be of interest. The risk for acquiring tularemia, however, is relatively small even in the disease-endemic areas, where the overall incidence in this outbreak was approximately 66 per 100,000 population. On the basis of these findings, recommendations to the population in general about not owning a cat therefore seem unwarranted. However, informing the public about the risk of spread of tularemia from cats to humans seems reasonable. In the separate analysis of risk factors, owning a cat and being bitten by mosquitoes appeared as independent risk factors in both groups. Farming appeared as a risk factor only in the disease-endemic area. The reason for this difference remains unknown and merits investigation. One explanation could be different farming practices, since the disease-endemic areas are heavily forested with small plots of arable land In geography, arable land (from Latin arare, to plough) is an agricultural term, meaning land that can be used for growing crops. Of the earth's 148,000,000 km² (57 million square miles) of land, approximately 31,000,000 km² (12 million square miles) are interspersed, but the emergent areas have more open, continuous farmland. No new risk factors were found in the emergent group that could explain the spread of tularemia into new areas. However, mosquito bites and spending time "Spending Time" is the first single released by Christian artist Stellar Kart. The lyrics describe the band members desire to spend "more time with God". "Sometimes it’s a real struggle to spend time with God. in the forest play a relatively bigger role in the emergent areas, but farming and contact with cats were relatively more important in the disease-endemic area (Tables 1 and 2). This finding may suggest that reservoirs in the new areas have not yet come into close contact with human settlements. The higher proportion of pneumonia in the disease-endemic area, which cannot fully be explained by greater diagnostic acumen among clinicians more familiar with the disease, could also indicate some kind of environmental contamination in areas where tularemia has long been established. The parallel of our findings with the recently described small outbreak of pneumonic pneumonic /pneu·mon·ic/ (noo-mon´ik) 1. pulmonary (1). 2. pertaining to pneumonia. pneu·mon·ic adj. 1. Relating to, affected by, or similar to pneumonia. tularemia in landscapers on Martha's Vineyard Martha's Vineyard (vĭn`yərd), island (1990 est. pop. 8,900), c.100 sq mi (260 sq km), SE Mass., separated from the Elizabeth Islands and Cape Cod by Vineyard and Nantucket sounds. is intriguing (19). This study has elucidated some of the basic epidemiology of human tularemia in Sweden. More research is needed on the epidemiology of the disease in animals. Important questions that remain unanswered are--What is the reservoir (or reservoirs)? What is the interaction between infection in different wild species? And what triggers an outbreak in humans? A follow-up field study with collection of samples from mosquitoes, water, and rodents is planned.
Table 1. Results of case-control analysis of risk factors for
outbreak-associated tularemia, Sweden, 2000
95%
Matched confidence
Risk factors Cases Controls odds ratio interval
Univariate analysis
Mosquito bites 196/202 313/392 8.3 3.3 to 21
Owning a cat 69/218 82/414 2.0 1.3 to 3.1
Farming 30/210 24/397 3.2 1.6 to 6.3
Visiting wooded areas 146/206 221/397 1.7 1.2 to 2.5
Owning a dog 32/218 73/414 0.75 0.45 to 1.3
Visiting golf courses 37/215 34/398 1.7 0.9 to 3.0
Visiting lakes
and rivers 160/212 259/391 1.5 0.95 to 2.3
Multivariate analysis
Mosquito bites 196/202 313/392 8.8 3.3 to 23
Owning a cat 69/218 82/414 2.5 1.5 to 4.2
Farming 30/210 24/397 3.2 1.4 to 7.0
Table 2. Comparison of risk factors for tularemia in disease-endemic
and -emergent areas, Sweden, 2000
Disease-endemic areas
Matched odds
Risk factors Cases Controls ratio 95% CI (a)
Univariate analysis
Mosquito bites 78/81 119/152 8.4 1.9 to 37
Owning a cat 37/84 29/159 4.4 2.2 to 9.0
Farming 15/81 8/152 7.5 2.1 to 27
Visiting wooded 50/79 85/152 1.1 0.6 to 1.9
areas
Multivariate analysis
Mosquito bites 7.6 1.6 to 36
Owning a cat 4.0 1.6 to 10
Farming 4.9 1.1 to 22
Emergent areas
Matched odds
Risk factors Cases Controls ratio 95% CI
Univariate analysis
Mosquito bites 93/94 150/181 9.1 2.1 to 40
Owning a cat 29/105 38/195 1.6 0.8 to 3.0
Farming 9/101 15/186 0.8 0.3 to 2.3
Visiting wooded 75/100 102/186 2.4 1.3 to 4.3
areas
Multivariate analysis
Mosquito bites 9.4 2.1 to 43
Owning a cat 2.5 1.2 to 5.5
Farming
(a) CI, confidence interval.
Acknowledgments We thank our colleagues at the National Institute of Public Health in Finland, in particular Markku Kuusi, for sharing their tularemia questionnaire with us. We also acknowledge the valuable work of Monica Bjornor Maj-Britt Ekegren, Aino Johansson, Anne Lennell, Per-Arne Parment, Ingrid Persson, and Bodil Petersen from the County Medical Officer's Units of the counties in the study. References (1.) Markowitz LE, Hynes NA, de la Cruz de la Cruz is a common surname in the Spanish language meaning 'of The Cross.'
 s), city (1996 pop. 391,299), Rio de Janeiro state, SE Brazil, on the Paraíba River near its mouth. E, Barbaree JM,
Plikaytis BD, et al. Tick-borne tularemia. An outbreak of
lymphadenopathy lymphadenopathy /lym·phad·e·nop·a·thy/ (-op´ah-the) disease of the lymph nodes.angioimmunoblastic lymphadenopathy , angioimmunoblastic lymphadenopathy with dysproteinemia in children. JAMA JAMA abbr. Journal of the American Medical Association 1985;254:2922-5. (2.) Evans ME, Gregory DW, Schaffner W, McGee ZA. Tularemia: a 30-year experience with 88 cases. Medicine (Baltimore) 1985;64:251--69. (3.) Taylor JP, Istre GR, McChesney TC, Satalowich FT, Parker RL, McFarland LM. Epidemiologic characteristics of human tularemia in the southwest-central states, 1981-1987. Am J Epidemiol 1991;133:1032-8. (4.) Brooks GF, Buchanan TM. Tularemia in the United States United States, officially United States of America, republic (2005 est. pop. 295,734,000), 3,539,227 sq mi (9,166,598 sq km), North America. The United States is the world's third largest country in population and the fourth largest country in area. : epidemiologic aspects in the 1960s and follow-up of the outbreak of tularemia in Vermont. J Infect Dis 1970;121:357-9. (5.) Langley R, Campbell R. Tularemia in North Carolina North Carolina, state in the SE United States. It is bordered by the Atlantic Ocean (E), South Carolina and Georgia (S), Tennessee (W), and Virginia (N). Facts and Figures Area, 52,586 sq mi (136,198 sq km). Pop. , 1965-1990. North Carolina Medical Journal 1995;56:314-7. (6.) Boyce JM. Recent trends in the epidemiology of tularemia in the United States. J Infect Dis 1975;131:197-9. (7.) Dahlstrand S, Ringertz O, Zetterberg B. Airborne tularemia in Sweden. Scand J Infect Dis 1971;3:7-16. (8.) Tarnvik A, Sandstrom G, Sjostedt A. Epidemiological analysis of tularemia in Sweden 1931-1993. FEMS FEMS Federation of European Microbiological Societies FEMS Federation of European Materials Societies FEMS Fabrication Engineering Management System FEMS Facility Equipment Maintenance System (PMEL/TMDE) Immunol Meal Microbiol 1996;13:201-4. (9.) Olin G. Occurrence and mode of transmission of tularemia in Sweden. Acta Pathol Microbiol Scand 1942;19:220-47. (10.) Christenson B. An outbreak of tularemia in the northern part of central Sweden. Scand J Infect Dis 1984;16:285-90. (11.) Syrjala H, Kujala P, Myllyla V, Salminen A. Airborne transmission airborne transmission Epidemiology The transmission of pathogens by aerosol, which enter the body by the respiratory tract. See Aerosol. of tularemia in farmers. Scand J Infect Dis 1985;17:371-5. (12.) Capellan J, Fong IW. Tularemia from a cat bite: case report and review of feline-associated tularemia. Clin Infect Dis 1993;16:472-5. (13.) Woods JP, Crystal MA, Morton RJ, Panciera RJ. Tularemia in two cats. J Am Vet Med Assoc 1998;212:81-3. (14.) Liles WC, Burger RJ. Tularemia from domestic cats. West J Med 1993;158:619-22. (15.) von Schroeder HP, McDougall EP. Ulceroglandular and pulmonary tularemia: a case resulting tkmn a cat bite to the hand. J Hand Surg [Am] 1993;18:132-4. (16.) Rhyan JC, Gahagan T, Fales WH. Tularemia in a cat. J Vet Diagn Invest 1990;2:239-41. (17.) Baldwin CJ, Panciera RJ, Morton RJ, Cowell AK, Waurzyniak BJ. Acute tularemia in three domestic cats. J Am Vet Med Assoc 1991;199:1602-5. (18.) Scheel O, Reiersen R, Hoel T. Treatment of tularemia with ciprofloxacin ciprofloxacin /cip·ro·flox·a·cin/ (sip?ro-flok´sah-sin) a synthetic antibacterial effective against many gram-positive and gram-negative bacteria; used as the hydrochloride salt. cip·ro·flox·a·cin n. . Eur J Clin Microbiol Infect Dis 1992;11:447-8. (19.) Feldman KA, Enscore RE, Lathrop SL, Matyas BT, McGuill M, Schriefer ME, et al. An outbreak of primary pneumonic tularemia on Martha's Vineyard. N Engl J Med 2001 ;345:1601-6. Address for correspondence: Anders Tegnell, Dept. of Epidemiology, Swedish Institute for Infectious Disease Control, SE-171 82 Solna, Sweden; fax: 46830062; e-mail: anders.tegnell@smi.ki.se Henrik Eliasson, * Johan Lindback, ([dagger]) J. Pekka Nuorti, ([double dagger double dagger n. A reference mark (  ) used in printing and writing. Also called diesis.Noun 1. ]) Malin Arneborn, ([dagger]) Johan Giesecke, ([dagger]) and Anders Tegnell ([dagger]) * Orebro University Hospital, Orebro, Sweden; ([dagger]) Swedish Institute for Infectious Disease Contrel, Solna, Sweden; and ([double dagger]) National Public Health Institute, Helsinki, Finland |
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