Trans R Soc Trop Med Hyg 2014; 108: 516–518 doi:10.1093/trstmh/tru094 Advance Access publication 18 June 2014 Serological survey of tularemia among butchers and slaughterhouse workers in Iran Saber Esmaeilia,b, Behzad Esfandiaria,b, Max Maurinc,d, Mohammad Mehdi Gouyae, SHORT COMMUNICATION Mohammad Reza Shirzadie, Fahimeh Bagheri Amiria,f and Ehsan Mostafavia,b,* aDepartment of Epidemiology, Pasteur Institute of Iran, Tehran, Iran; bResearch Centre for Emerging and Reemerging Infectious Diseases (Akanlu), Pasteur Institute of Iran, Kabudar-Ahang, Hamadan, Iran; cCNR Francisella, Laboratoire de Bacte´riologie, De´partement des Agents Infectieux, Institut de Biologie et de Pathologie, CHU de Grenoble, Universite´ Joseph Fourier, Grenoble, France; dLAPM, CNRS UMR e f EAFC, Grenoble, France; Center of Disease Control (CDC), Ministry of Health, Tehran, Iran; Faculty of Veterinary Medicine, University of Downloaded from Tehran, Tehran, Iran *Corresponding author: Present address: Department of Epidemiology, Pasteur Institute of Iran, 69 Pasteur Ave., Tehran 1316943551, Iran. Tel/Fax: +98 21 66496448; E-mail: [email protected] Received 4 January 2014; revised 29 March 2014; accepted 25 April 2014 http://trstmh.oxfordjournals.org/ Background: Tularemia is a zoonotic disease caused by the Gram-negative bacterium Francisella tularensis. Human infections often occur through manipulation of infected animals or animal carcasses. Methods: In this study, we determined the tularemia seroprevalence in butchers and slaughterhouse workers in 10 counties of Sistan and Baluchestan Province in Iran. Results: A mean seroprevalence of 6.5% for IgG antibodies against F. tularensis was seen. The highest seroposi- tivity rates were observed in the counties of Zabol and Nikhshahr. There was no difference in the seroprevalence rates between butchers and slaughterhouse workers (p¼0.25). at Queen's University on September 19, 2014 Conclusion: These data suggest that tularemia is endemic in Sistan and Baluchestan Province in Iran. Keywords: Francisella tularensis, Iran, Seroprevalence, Sistan and Baluchestan Province, Tularemia, Zoonosis Introduction antibodies were also detected in an Afghan hedgehog in the same year.7 The first human case of tularemia in Iran was Francisella tularensis is the etiological agent of tularemia. There reported in the city of Marivan, southwest Kurdistan (western are two subspecies of F. tularensis, namely F. tularensis subspecies Iran) in 1980.8In a recent study (2011–2012) among different tularensis (type A strain) commonly found in North America and groups in western Iran, the rate of tularemia seroprevalence F. tularensis subspecies holarctica (type B strain) found in the was 14.4%.9 In this study, 16% of the butchers were seropositive 1 whole northern hemisphere. Type B strains are responsible for for tularemia. The aim of the study was to determine the sero- almost all tularemia cases in Europe and Asia, and are usually asso- prevalence of F. tularensis in southeastern Iran and to establish ciated with less severe symptoms and lower mortality rates as com- a baseline for surveillance of the disease in the country. Because 2,3 pared to type A strains. F. tularensis has a large animal reservoir, anti-F. tularensis antibodies were previously reported in domestic which includes many terrestrial mammals (especially rodents and animals, sera from butchers and slaughterhouse workers were 2 lagomorphs) and arthropods (especially ticks). Human infections studied. These occupational groups may develop tularemia usually occur through direct contact with infected animals or ani- after contact with blood or tissues from animals infected with mal carcasses. Alternatively, infection may occur via tick (or other F. tularensis or healthy carriers of this bacterium, or via the bite arthropod) bites or after exposure to a contaminated environ- of infected ticks during slaughtering operations.10 ment.3,4 The clinical manifestations of tularemia may vary from an asymptomatic infection to a severe and possibly fatal disease. Six clinical forms are classically recognized: ulceroglandular, glandu- Materials and methods lar, oculoglandular, oropharyngeal, pneumonic and typhoidal.1,5 In Iran, antibodies against F. tularensis were detected in The study area domestic animals (cattle and sheep) in the northwest, and in a This cross-sectional study was carried out in Sistan and porcupine in the southeast (Zabol county) in 1973.6 F. tularensis Baluchistan Province, in southeastern Iran, in 2011. This province # The Author 2014. Published by Oxford University Press on behalf of Royal Society of Tropical Medicine and Hygiene. All rights reserved. For permissions, please e-mail: [email protected]. 516 Transactions of the Royal Society of Tropical Medicine and Hygiene is bordered by the Oman Sea to the south, Afghanistan and Statistical analysis Pakistan to the east, the South Khorasan province to the north, Data were analyzed with SPSS statistical software, 16th version and the provinces of Kerman and Hormozgan to the west (SPSSInc,Chicago,IL,USA).Logisticregressionandx2 tests (Supplementary Figure 1). It has a dry, arid to semiarid climate. were used to compare the variables; p-values less than 0.05 were considered statistically significant. ArcGIS software version 9.3 (ESRI, Redlands, CA, USA) was used for mapping the results. Sampling In this study, 184 serum samples were collected from 120 butch- ers and 64 slaughterhouse workers from 10 counties of Sistan and Ethical considerations Baluchistan Province (including Zahak and Zabol in the north, The study was approved by the ethics committee of Pasteur Iranshahr,ZahedanandKhashinthecenterandChabahar, Institute of Iran. Sarbaz, Saravan and Konarak in the south of the province; Table 1). All official slaughterhouses in this province were recruited and participants were selected randomly from among the Results Downloaded from employees. All participants were male. The median (interquartile In total, 12 samples (6.5%, 95% CI 3.58–10.82%) had positive range) age and length of employment were 34 (25–45) years and IgG titers and 19 samples (10.3%) had borderline IgG titers 8 (3–15) years, respectively. The inclusion criteria were being over against F. tularensis antigen. Only two (6%) of the 31 sera positive 18 and working as a butcher or slaughterhouse worker for a min- or borderline for F. tularensis antibodies also displayed antibodies imum of 6 months. A 10 mL blood sample was collected from against Brucella abortus antigen. The highest F. tularensis sero- http://trstmh.oxfordjournals.org/ each participant after obtaining informed consent and demo- prevalence was observed in Zabol (10.5%) and Nikshahr (10.0%), graphic characteristics. Sera were kept at 2208C and transferred which are northern and southern counties, respectively. However, to the Department of Epidemiology of the Pasteur Institute of the mean seropositivity rates progressively declined from the nor- Iran (Tehran). thern (9.3%) to the central (6.3%) to southern (2.2%) regions of Sistan and Baluchistan Province, although these differences were not statistically significant (p¼0.37). We found no statistic- Serological tests ally significant difference (p¼0.25) between the F. tularensis sero- Collected sera were tested for the presence of IgG antibodies prevalence observed in butchers (5.0%) and slaughterhouse against F. tularensis, using a commercial ELISA kit (Virion/Serion, workers (9.4%). The F. tularensis seroprevalence rates were not Wu¨rzburg, Germany) according to the manufacturer’s instructions correlated to age (p¼0.94) and length of employment (p¼0.19) at Queen's University on September 19, 2014 (positive cut-off titer .15 U/mL, borderline cut-off titers 10–15 U/mL). of participants. Serum samples with positive or borderline results for F. tularensis were further tested against Brucella antigen because of the pos- sibility of serological cross-reactions between both antigens. We Discussion used a locally prepared antigen and a standard tube agglutination Our study shows the presence of IgG antibodies against F. tularen- test elaborated by the Pasteur Institute of Iran. sis in 6.5% of the 184 healthy butchers and slaughterhouse workers investigated in Sistan and Baluchestan province, in south-eastern Iran. The ELISA test we used for screening of anti-F. tularensis IgG antibodies is considered to have a specificity Table 1. Seroprevalence of IgG antibodies against Francisella rate higher than 95%, close to the 98.1% specificity reported for 11 tularensis among butchers and slaughterhouse workers in different the western blot technique. False positive results for tularemia counties and regions of Sistan and Baluchestan Province in serology have been mainly observed in brucellosis patients, southeastern Iran owing to serological cross reactions between F. tularensis and Brucella spp.antigens.12 However, in this study, only 6.5% of serum samples positive for anti-F. tularensis antibodies also dis- Region No. tested County No. tested played anti-Brucella sp. antibodies. Thus, it is highly probable (seropositivity %) (seropositivity %) that positive F. tularensis ELISA tests found in butchers and slaughterhouse workers represent true tularemia infections. North 43 (9.3) Zabol 38 (10.5) Because the seropositive participants were asymptomatic, posi- Zahak 5 (0) tive antibody titers probably indicated past tularemia infections. Central 96 (6.3) Zahedan 70 (8.8) It is also possible that they were recent but asymptomatic Iranshahr