Volotão A C, Costa-Macedo L M, Haddad F S M, Brandão A, Peralta J M, Fernandes O
Departamento de Medicina Tropical, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Av. Brazil 4365, Manguinhos, Rio de Janeiro, RJ 21045-090, Brazil.
Acta Trop. 2007 Apr;102(1):10-9. doi: 10.1016/j.actatropica.2007.02.010. Epub 2007 Feb 25.
Giardia duodenalis is one of the major diarrhea agents in human and animals distributed worldwide, and present high levels of genetic diversity, showing seven genotypes: A, B, C, D, E, F, and G. Only Assemblages A and B have been detected in humans and in a wide range of other mammalians hosts, whereas the remaining Assemblages (C-G) are host-specific. Molecular characterization of cysts of human and animal origin are useful to address the co-circulate isolates between these host, and represents an objective means to evaluate zoonotic infection hypothesis. In the present work the G. duodenalis genotypes were characterized by restriction fragment length polymorphisms and DNA sequencing analysis of PCR products of the beta-giardin gene. The cysts were collected in the city of Rio de Janeiro, in Brazil, from a population composed by humans (n=366, 310 children and 56 adults), domestic animals (n=11) from a municipal daycare center in the surroundings of a slum and neighborhood medium-high class domestic animals (n=18). Parasitological exams were developed in human fecal samples. Parasites were found in 60% (186/310) and 66% (37/56) of the samples from children and adults, respectively. Among children's samples, 27.7% (86/310) were positive for G. duodenalis. Only 1.7% (1/56) of the adults was positive for this parasite. In general a total of 87 fecal samples (86 from children and 1 from adult) from all population studied were positive for G. duodenalis, and 62 of these were subjected to molecular analysis using a PCR that amplified a fragment of the beta-giardin gene. Sixty samples were typed as genotype A1, two as genotype A2 and genotype B was not encountered. Among domestic animals samples (n=29), eight (seven dogs and one cat) from the slum community were identified as genotype A1, and all control samples (n=18) were negative in the molecular assay. The host-specific genotypes C, D and, F were not found. In this study we described single case of G. duodenalis infection associated with a child and her dog and both isolates characterized as genotype A1. Despite the low incidence, this data suggest the putative existence of a zoonotic cycle of G. duodenalis in the studied population.
十二指肠贾第虫是全球范围内人类和动物主要的腹泻病原体之一，具有高度的遗传多样性，呈现出七种基因型：A、B、C、D、E、F和G。仅在人类和多种其他哺乳动物宿主中检测到A和B两种基因型组合，而其余的基因型组合（C - G）具有宿主特异性。对人和动物来源的包囊进行分子特征分析，有助于研究这些宿主之间共同传播的分离株，并且是评估人畜共患感染假说的一种客观手段。在本研究中，通过对β-贾第虫基因的PCR产物进行限制性片段长度多态性分析和DNA测序，对十二指肠贾第虫的基因型进行了特征分析。包囊采集于巴西里约热内卢市，来自以下人群：人类（n = 366，其中310名儿童和56名成人）、来自贫民窟周边一个市立日托中心的家畜（n = 11）以及中高收入社区的家畜（n = 18）。对人类粪便样本进行了寄生虫学检查。在儿童样本和成人样本中，分别有60%（186/310）和66%（37/56）检测到寄生虫。在儿童样本中，27.7%（86/310）的十二指肠贾第虫检测呈阳性。只有1.7%（1/56）的成人该寄生虫检测呈阳性。总体而言，在所研究的所有人群中，共有87份粪便样本（86份来自儿童，1份来自成人）的十二指肠贾第虫检测呈阳性，其中62份样本使用扩增β-贾第虫基因片段的PCR进行了分子分析。60份样本被鉴定为A1基因型，2份为A2基因型，未检测到B基因型。在家畜样本（n = 29）中，贫民窟社区的8份样本（7只狗和1只猫）被鉴定为A1基因型，所有对照样本（n = 18）在分子检测中均为阴性。未发现宿主特异性基因型C、D和F。在本研究中，我们描述了一例十二指肠贾第虫感染病例，涉及一名儿童及其宠物狗，两者的分离株均被鉴定为A1基因型。尽管发病率较低，但这些数据表明在所研究的人群中可能存在十二指肠贾第虫的人畜共患传播循环。
