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ORIGINAL ARTICLESeroprevalence of Toxoplasma gondii Infection in Stray and Household Cats in Guangzhou, ChinaH. Zhang1, D. H. Zhou1, P. Zhou1, Z. R. Lun2, X. G. Chen3, R. Q. Lin1, Z. G. Yuan1 and X. Q. Zhu11 Laboratory of Parasitology, College of Veterinary Medicine, South China Agricultural University, 483 Wushan Street, Tianhe District, Guangzhou, Guangdong Province 510642, Peoples Republic of China2 Center for Parasitic Organisms, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou, Guangdong Province 510275, Peoples Republic of China3 Department of Parasitology, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou, Guangdong Province 510515, Peoples Republic of ChinaRunning Head: Toxoplasma gondii infection in cats in Guangzhou, ChinaCorrespondence:X.Q. Zhu. College of Veterinary Medicine, South China Agricultural University, 483 Wushan Street, Tianhe District, Guangzhou, Guangdong Province 510642, Peoples Republic of China. Tel: +86 20 85283730; Fax: +86 20 85283730; E-mail: Impactsl This article shows new figures on the present situation of Toxoplasma gondii infection in stray and household cats in metropolitan Guangzhou, China.l The data presented provide the most comprehensive picture of the prevalence of T. gondii in stray and household cats in Guangzhou, which also indicates the zoonotic significance of the prevalence. l The data presented provide “base-line” information for assessing the effectiveness of future control strategies against T. gondii infection in cats in Guangzhou, China.Summary The prevalence of anti-Toxoplasma gondii specific IgG in stray and household cats in Guangzhou, China was determined by ELISA on serum samples from 206 cats (117 strays and 89 households), and the overall infection rate was 25.24%. The infection rate in stray cats (30.77%) was significantly higher (p 0.05) than in household cats (17.98%). The rate of infection between male and female cats of both groups was not significantly different (p0.05), 28.13% versus 32.61% for male and female in stray cats, respectively, and 18% versus 17.95% in household cats. The present investigation demonstrated that the prevalence of T. gondii infection in cats in Guangzhou was high, especially in stray cats, which are probably the main source of T. gondii infection in this area. Integrated control strategies and measures should be implemented to prevent and control T. gondii infection in both stray and household cats, which will have significant implications for the control of human infection with T. gondii.Keywords: Cat; ELISA; Guangzhou; Seroepidemiology; Toxoplasma gondii; ToxoplasmosisIntroductionToxoplasma gondii is an obligate intracellular protozoa parasite that can infect a variety of cell types from a wide range of mammals and birds throughout the world, including humans and nonhuman primates (Jacobs et al., 1998). T. gondii infection does not usually produce clinical symsptoms. However, the primary infection during pregnancy in women and animals may cause abortion, fetal abnormalities or prenatal death (Cook et al., 2000). More importantly, T. gondii infection is considered one of the main reasons of death for the AIDS patients and other immunocompromised patients (Montoya and Liesenfeld, 2004). Felids play a crucial role in the epidemiology of this parasitic disease, because they are the only definitive host, shedding and excreting millions of infective oocysts in a short period of time (Dubey, 1994) in their faeces. It is generally suggested that cats probably play a major role in transmitting T. gondii through environments contaminated by faeces. It is not convenient and may have difficulty in detecting T. gondii oocysts in faecal examination of cats. Therefore, serologic investigation of cats is important for determining the epidemiological significance of T. gondii infection.Antibodies to T. gondii have been reported in cats worldwide. There have also been some surveys of T. gondii infections in cats in some provinces of China in recent years (Lu et al. 1997; Yu et al., 2006; Yuan et al. 2004; unfortunately, these reports were published only in the Chinese language). However, the difference of T. gondii infection between stray and household cats and the infection rates between male ad female cats are not quite clear. In order to provide a foundation for the improved control of T. gondii infection in cats, the aim of the present investigation was to estimate the prevalence of T. gondii in stray and household cats in metropolitan Guangzhou, China.Material and methodsAnimals Biometric data for cats including age, sex and lifestyle were recorded. The information about household cats was taken from the owners and the information about stray cats was estimated based on body condition and by examining dentition.Blood sampling and serum preparationBlood samples (1.5 ml) were collected from each cat into sterile plain tube by jugular puncture. The samples were left to clot at room temperature for 3 h and then centrifuged at 800 g for 10 min. Each serum sample was transferred into a 0.5 ml sterile tube and preserved at 20 until needed for ELISA.Determination of antibodies to T. gondiiAntibodies to T. gondii were determined using the CIVTEST T. gondii ELISA Kit (Shenzhen, China) according to the manufacturers instructions. Positive and negative control sera were provided in the kit. The tests were performed in the Veterinary College of South China Agricultural University. Briefly, the T. gondii specific antigen was coated on a 96-well ELISA plate. After incubation of the diluted serum sample (1:100) in the test well and subsequent washing, a conjugate was added. The plate was washed again, and then a chromogenic enzyme substrate was added. The optical density (OD) at 450 nm was read using a photometer (BIO-RAD).A relative rate percent (IRPC) value was obtained using the following formula:The sera were considered negative to T. gondii if the IRPC 2.1. It is to take as 0.7 when the value (meanOD450 negative control - meanOD450 blank control) was less than 0.7.Statistical analysisDifferences in the seroprevalence of infected cats between stray and household groups, between male and female cats were analyzed using Chi Square Test in SPSS for Windows, (Release 11.0 standard version, SPSS Inc.). The correlation between the rates of infection in different age groups was calculated with Excel (Microsoft Excel 2003).Results and discussionIn this investigation, the ELISA method was utilized due to the ease of its application, and its high sensitivity and specificity when compared with other test methods (Lappin and Powell, 1991). In this study, 206 cats (117 households and 89 strays were examined. Of these, 82 were male, 85 were female and 39 unknown sex (Table 1). As shown in Table 1, the overall seroprevalence rate was 25.24%. Seroprevalence for all different groups was 30.77% in stray cats and 17.98% in household cats (Table 1), and ranging from 12.50% to 30.77% in different age groups (Table 2).The seroprevalence of T. gondii in cats has been studied in many countries. In the present study, the overall seroprevalence in cats was 25.24%, which was lower than that reported in other countries (Miro et al., 2004; Haddadzadeh et al., 2006), and in Shanghai and Hebei province in China (Lu et al. 1997; Yuan et al. 2004), but similar to that reported in Beijing (Yu et al., 2006).In the present investigation, although both groups of cats were infected with T. gondii, the seroprevalence of infection in stray cats (30.77%) was significantly higher (p 3 years category of cats compared with a seropositive rate of 12.50% in cats 1 years old. As shown in table 2, seroprevalence varies in different age groups, ranging from 12.50% to 30.77%. The difference in prevalence found with respect to age (adults versus juveniles) coincides with other studies where higher prevalence is observed in the adult group than in the juvenile one (Smith et al., 1992; Gauss et al., 2003), showing that with the increase of age the risk of exposure to T. gondii increases (Frenkel, 1990; Hill et al., 2000).ConclusionsThe present investigation revealed that the prevalence of T. gondii infection in cats in Guangzhou was quite higher, especially in stray cats, which are probably the main source of T. gondii infection in this area. Integrated control strategies and measures should be implemented to prevent and control T. gondii infection in both stray and household cats, which will have significant implications for the control of human infection with T. gondii. Acknowledgements This work is supported, in part, by grants from the National Basic Research Program of China (Grant No. 2007CB116301), the National Special Research Programs for Non-Profit Trades (Agriculture) (Grant No. 200803017), the Key Research Programs in Natural Sciences for Institutions of Higher Education in Guangdong Province (Grant No. 06Z004), and the Program for Changjiang Scholars and Innovative Research Team in University (Grant No. IRT0723).ReferencesCook, A. J., R. E. Gilbert, W. Buffolano, J. Zufferey, E. Petersen, P. A. Jenum, W. Foulon, A. E. Semprini, and D. T. Dunn, 2000: Sources of Toxoplasma infection in pregnant women: European multicentre case-control study. Br. Med. J. 312, 142147. DeFeo, M. L., J. P. Dubey, T. N. Mather, and R. C. Rhodes III, 2002: Epidemiologic investigation of seroprevalence of antibodies to Toxoplasma gondii in cats and rodents. Am. J. Vet. Res. 63, 17141717.Dubey, J. P., 1994: Toxoplasmosis. J. Am. Vet. Med. Assoc. 205, 15931598. 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