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Abstract：
BACKGROUND: Toxoplasma gondii (T. gondii) is a worldwide distributed protozoan parasite which has infected a wide range of warm-blooded animals and humans. The most common form of T. gondii infection is asymptomatic (latent); nevertheless, latent toxoplasmosis can induce various alterations of sex hormones, especially testosterone, in infected humans and animals. On the other hand, testosterone is involved in behavioral traits and reproductive functions in both sexes. Hence, the purpose of this systematic review is to summarize the available evidence regarding the association between T. gondii infection and testosterone alteration.
METHODS: In the setting of a systematic review, an electronic search (any date to 10 January 2023) without language restrictions was performed using Science Direct, Web of Science, PubMed, Scopus, and Google Scholar. The PRISMA guidelines were followed. Following the initial search, a total of 12,306 titles and abstracts were screened initially; 12,281 were excluded due to the lack of eligibility criteria or duplication. Finally, 24 articles met the included criteria. A mean±standard deviation (SD) was calculated to assess the difference of testosterone between T. gondii positive and T. gondii negative humans. The possibility of publication bias was assessed using Egger\'s regression. P-value < 0.05 was considered statistically significant.
RESULTS: This systematic review identified 24 articles (18 studies in humans and six studies in animals). Most human studies (13 out of 19) reported an increased level of testosterone following latent toxoplasmosis in males, while three studies reported decreased levels and two studies reported an insignificant change. Eleven articles (seven datasets in males and seven datasets in females) were eligible to be included in the data synthesis. Based on the random-effects model, the pooled mean± SD of testosterone in T. gondii positive than T. gondii negative was increased by 0.73 and 0.55 units in males and females, respectively. The Egger\'s regression did not detect a statistically significant publication bias in males and females (p = value = 0.95 and 0.71), respectively. Three studies in male animals (rats, mice, and spotted hyenas) and two studies in female animals (mice and spotted hyenas) reported a decline in testosterone in infected compared with non-infected animals. While, one study in female rats reported no significant changes of testosterone in infected than non-infected animals. Moreover, two studies in male rats reported an increased level of testosterone in infected than non-infected animals.
CONCLUSIONS: This study provides new insights about the association between T. gondii infection and testosterone alteration and identifies relevant data gaps that can inform and encourage further studies. The consequence of increased testosterone levels following T. gondii infection could partly be associated with increased sexual behavior and sexual transmission of the parasite. On the other hand, declining testosterone levels following T. gondii infection may be associated with male reproductive impairments, which were observed in T. gondii-infected humans and animals. Furthermore, these findings suggest the great need for more epidemiological and experimental investigations in depth to understand the relationship between T. gondii infection and testosterone alteration alongside with future consequences of testosterone alteration.
METHODS: In the setting of a systematic review, an electronic search (any date to 10 January 2023) without language restrictions was performed using Science Direct, Web of Science, PubMed, Scopus, and Google Scholar. The PRISMA guidelines were followed. Following the initial search, a total of 12,306 titles and abstracts were screened initially; 12,281 were excluded due to the lack of eligibility criteria or duplication. Finally, 24 articles met the included criteria. A mean±standard deviation (SD) was calculated to assess the difference of testosterone between T. gondii positive and T. gondii negative humans. The possibility of publication bias was assessed using Egger\'s regression. P-value < 0.05 was considered statistically significant.
RESULTS: This systematic review identified 24 articles (18 studies in humans and six studies in animals). Most human studies (13 out of 19) reported an increased level of testosterone following latent toxoplasmosis in males, while three studies reported decreased levels and two studies reported an insignificant change. Eleven articles (seven datasets in males and seven datasets in females) were eligible to be included in the data synthesis. Based on the random-effects model, the pooled mean± SD of testosterone in T. gondii positive than T. gondii negative was increased by 0.73 and 0.55 units in males and females, respectively. The Egger\'s regression did not detect a statistically significant publication bias in males and females (p = value = 0.95 and 0.71), respectively. Three studies in male animals (rats, mice, and spotted hyenas) and two studies in female animals (mice and spotted hyenas) reported a decline in testosterone in infected compared with non-infected animals. While, one study in female rats reported no significant changes of testosterone in infected than non-infected animals. Moreover, two studies in male rats reported an increased level of testosterone in infected than non-infected animals.
CONCLUSIONS: This study provides new insights about the association between T. gondii infection and testosterone alteration and identifies relevant data gaps that can inform and encourage further studies. The consequence of increased testosterone levels following T. gondii infection could partly be associated with increased sexual behavior and sexual transmission of the parasite. On the other hand, declining testosterone levels following T. gondii infection may be associated with male reproductive impairments, which were observed in T. gondii-infected humans and animals. Furthermore, these findings suggest the great need for more epidemiological and experimental investigations in depth to understand the relationship between T. gondii infection and testosterone alteration alongside with future consequences of testosterone alteration.
摘要：
背景：弓形虫（T。gondii）是一种遍布全球的原生动物寄生虫，已感染了多种温血动物和人类。弓形虫感染的最常见形式是无症状（潜伏）；然而，潜伏弓形虫病可以诱导性激素的各种改变，尤其是睾丸激素,在受感染的人类和动物中。另一方面,睾酮与两性的行为特征和生殖功能有关。因此，本系统综述的目的是总结有关弓形虫感染与睾酮改变之间关联的现有证据.
方法：在系统评价的背景下，使用ScienceDirect进行了无语言限制的电子搜索（截至2023年1月10日的任何日期），WebofScience,PubMed,Scopus,谷歌学者。遵循PRISMA准则。在最初的搜索之后,最初共筛选了12,306份标题和摘要;由于缺乏资格标准或重复,12,281份被排除.最后,24篇文章符合纳入标准。计算平均值±标准偏差(SD)以评估弓形虫阳性和弓形虫阴性人类之间的睾酮差异。使用Egger回归评估发表偏倚的可能性。P值<0.05被认为具有统计学意义。
结果：本系统综述确定了24篇文章（18项人类研究和6项动物研究）。大多数人类研究（19个中的13个）报告了男性潜伏弓形虫病后睾丸激素水平升高，而三项研究报告水平下降，两项研究报告变化不明显。11篇文章（男性的七个数据集和女性的七个数据集）符合纳入数据综合的条件。基于随机效应模型，弓形虫阳性的睾酮的合并平均值±SD比弓形虫阴性的睾酮增加了0.73和0.55个单位，在男性和女性中，分别。Egger回归在男性和女性中没有检测到有统计学意义的发表偏倚（p=值=0.95和0.71），分别。对雄性动物的三项研究(大鼠，老鼠,和斑点鬣狗）和对雌性动物（小鼠和斑点鬣狗）的两项研究报告，与未感染动物相比，受感染动物的睾丸激素下降。同时,一项针对雌性大鼠的研究报告说，与未感染的动物相比，受感染的动物中的睾丸激素没有显着变化。此外，两项针对雄性大鼠的研究报告,受感染动物的睾酮水平高于未受感染动物.
结论：这项研究提供了有关弓形虫感染与睾酮改变之间关联的新见解，并确定了相关数据空白，可以为进一步研究提供信息和鼓励。弓形虫感染后睾丸激素水平升高的结果可能部分与性行为增加和寄生虫的性传播有关。另一方面,弓形虫感染后睾丸激素水平下降可能与男性生殖障碍有关，在弓形虫感染的人类和动物中观察到。此外，这些研究结果表明,需要进行更深入的流行病学和实验研究,以了解弓形虫感染与睾酮改变之间的关系,以及睾酮改变的未来后果.
方法：在系统评价的背景下，使用ScienceDirect进行了无语言限制的电子搜索（截至2023年1月10日的任何日期），WebofScience,PubMed,Scopus,谷歌学者。遵循PRISMA准则。在最初的搜索之后,最初共筛选了12,306份标题和摘要;由于缺乏资格标准或重复,12,281份被排除.最后,24篇文章符合纳入标准。计算平均值±标准偏差(SD)以评估弓形虫阳性和弓形虫阴性人类之间的睾酮差异。使用Egger回归评估发表偏倚的可能性。P值<0.05被认为具有统计学意义。
结果：本系统综述确定了24篇文章（18项人类研究和6项动物研究）。大多数人类研究（19个中的13个）报告了男性潜伏弓形虫病后睾丸激素水平升高，而三项研究报告水平下降，两项研究报告变化不明显。11篇文章（男性的七个数据集和女性的七个数据集）符合纳入数据综合的条件。基于随机效应模型，弓形虫阳性的睾酮的合并平均值±SD比弓形虫阴性的睾酮增加了0.73和0.55个单位，在男性和女性中，分别。Egger回归在男性和女性中没有检测到有统计学意义的发表偏倚（p=值=0.95和0.71），分别。对雄性动物的三项研究(大鼠，老鼠,和斑点鬣狗）和对雌性动物（小鼠和斑点鬣狗）的两项研究报告，与未感染动物相比，受感染动物的睾丸激素下降。同时,一项针对雌性大鼠的研究报告说，与未感染的动物相比，受感染的动物中的睾丸激素没有显着变化。此外，两项针对雄性大鼠的研究报告,受感染动物的睾酮水平高于未受感染动物.
结论：这项研究提供了有关弓形虫感染与睾酮改变之间关联的新见解，并确定了相关数据空白，可以为进一步研究提供信息和鼓励。弓形虫感染后睾丸激素水平升高的结果可能部分与性行为增加和寄生虫的性传播有关。另一方面,弓形虫感染后睾丸激素水平下降可能与男性生殖障碍有关，在弓形虫感染的人类和动物中观察到。此外，这些研究结果表明,需要进行更深入的流行病学和实验研究,以了解弓形虫感染与睾酮改变之间的关系,以及睾酮改变的未来后果.
