刚地弓形虫感染广泛分布于世界各地,热带地区高发。根据美国 2009 年到 2010 年的数据,12 到 49 岁人群血清学阳性率为 10.1%,较1988 年到 1994 年的 16%有所减少。[2]Jones JL, Kruszon-Moran D, Rivera H, et al. Toxoplasma gondii seroprevalence in the United States 2009-2010 and comparison with the past two decades. Am J Trop Med Hyg. 2014;90:1135-1139.http://www.ncbi.nlm.nih.gov/pubmed/24710615?tool=bestpractice.com南欧的血清学阳性率高达 54%,主要原因为摄食未煮熟的肉以及厨房卫生较差。北美血清学阳性率也很高,为 43%-73%,其原因可能是水源传播的影响以及摄食未煮熟的肉。欧洲近 30 到 40 年间,年龄别发病率已有所下降。[3]Petersen E. Epidemiology, diagnostics, and chemotherapy. In: Ajioka JW, Soldati D, eds. Toxoplasma molecular and cellular biology. Norfolk, UK: Horizon Bioscience; 2007:chapter 3.尽管此病在印度 (45%) 和马来西亚 (56%)发病率较高,但在大多数亚洲国家血清阳性率仍较低(韩国妊娠女性为 1%,台湾地区 HIV 阳性患者为 10%)。[3]Petersen E. Epidemiology, diagnostics, and chemotherapy. In: Ajioka JW, Soldati D, eds. Toxoplasma molecular and cellular biology. Norfolk, UK: Horizon Bioscience; 2007:chapter 3.在欧洲,无免疫的妊娠女性血清学转化率范围为 2.4‰到 16‰;[4]Eskild A, Oxman A, Magnus P, et al. Screening for toxoplasmosis in pregnancy: what is the evidence of reducing a health problem? J Med Screen. 1996;3:188-194.http://www.ncbi.nlm.nih.gov/pubmed/9041483?tool=bestpractice.com在英国约为 2‰。[5]Health Protection Agency. Toxoplasmosis. http://www.hpa.org.uk (last accessed 22 June 2016).http://webarchive.nationalarchives.gov.uk/20140714084352/http://www.hpa.org.uk/HPA/Topics/InfectiousDiseases/InfectionsAZ/1191942176127/在美国,约有 5‰无免疫的女性可于妊娠期感染弓形虫,且其活产胎儿患先天性感染的发病率为 1‰ 到 10‰。[6]Montoya JG, Liesenfeld O. Toxoplasmosis. Lancet. 2004 Jun 12;363(9425):1965-76.http://www.ncbi.nlm.nih.gov/pubmed/15194258?tool=bestpractice.com如果不治疗,那么妊娠期感染将最终导致约 44% 的新生儿先天感染,但如果于妊娠期进行适当的治疗,则可使新生儿先天感染率降至 29%。[7]Desmonts G. Couvreur J. Congenital toxoplasmosis: a prospective study of 378 pregnancies. N Eng J Med. 1974;290:1110-1116.http://www.ncbi.nlm.nih.gov/pubmed/4821174?tool=bestpractice.com[8]Dunn D, Wallon M, Peyron F, et al. Mother-to-child transmission of toxoplasmosis: risk estimates for clinical counseling. Lancet. 1999;353:1829-1833.http://www.ncbi.nlm.nih.gov/pubmed/10359407?tool=bestpractice.com
在欧洲和北美,刚地弓形虫有三种主要类型:I 型、II 型和 III 型,其中,I 型破坏性最大,而 III 型最小。II 型弓形虫于欧洲和北美地区的人类疾病中较常见。[9]Howe D, Sibley LD. Toxoplasma gondii comprises three clonal lineages: correlation of parasite genotype with human disease. J Infect Dis. 1995;172:1561-1566.http://www.ncbi.nlm.nih.gov/pubmed/7594717?tool=bestpractice.com南美、非洲和亚洲人群患病中,寄生虫的基因背景更加多元化。[10]Zhou P, Zhang H, Lin RQ, et al. Genetic characterization of Toxoplasma gondii isolates from China. Parasitol Int. 2009;58:193-195.http://www.ncbi.nlm.nih.gov/pubmed/19567233?tool=bestpractice.com[11]Ferreira Ade M, Vitor RW, Gazzinelli RT, et al. Genetic analysis of natural recombinant Brazilian Toxoplasma gondii strains by multilocus PCR-RFLP. Infect Genet Evol. 2006;6:22-31.http://www.ncbi.nlm.nih.gov/pubmed/16376837?tool=bestpractice.com[12]Boughattas S, Ben-Abdallah R, Siala E, et al. Direct genotypic characterization of Toxoplasma gondii strains associated with congenital toxoplasmosis in Tunisia (North Africa). Am J Trop Med Hyg. 2010;82:1041-1046.http://www.ncbi.nlm.nih.gov/pubmed/20519598?tool=bestpractice.com