Nukeri Sophy, Malatji Mokgadi Pulane, Sengupta Mita Eva, Vennervald Birgitte Jyding, Stensgaard Anna-Sofie, Chaisi Mamohale, Mukaratirwa Samson
School of Life Science, College of Agriculture, Engineering and Science, University of KwaZulu-Natal, Westville Campus, Durban 4001, South Africa.
Foundational Research & Services, South African National Biodiversity Institute, Pretoria 0001, South Africa.
Pathogens. 2022 Nov 6;11(11):1303. doi: 10.3390/pathogens11111303.
The occurrence of Fasciola gigantica and F. hepatica in Africa is well documented; however, unlike in Asia, there is a paucity of information on the existence of hybrids or parthenogenetic species on the continent. Nonetheless, these hybrid species may have beneficial characteristics, such as increased host range and pathogenicity. This study provides evidence of the potential existence of Fasciola hybrids in Africa. A literature search of articles published between 1980 and 2022 was conducted in PubMed, Google Scholar, and Science Direct using a combination of search terms and Boolean operators. Fasciola species were documented in 26 African countries with F. hepatica being restricted to 12 countries, whilst F. gigantica occurred in 24 countries, identified based on morphological features of adult Fasciola specimens or eggs and molecular techniques. The co-occurrence of both species was reported in 11 countries. However, the occurrence of potential Fasciola hybrids was only confirmed in Egypt and Chad but is suspected in South Africa and Zimbabwe. These were identified based on liver fluke morphometrics, assessment of the sperms in the seminal vesicle, and molecular techniques. The occurrence of intermediate host snails Galba truncatula and Radix natalensis was reported in Ethiopia, Egypt, South Africa, Tanzania, and Uganda, where F. hepatica and F. gigantica co-occurrences were reported. The invasive Pseudosuccinea columella snails naturally infected with F. gigantica were documented in South Africa and Egypt. In Zimbabwe, P. columella was infected with a presumed parthenogenetic Fasciola. This suggests that the invasive species might also be contributing to the overlapping distributions of the two Fasciola species since it can transmit both species. Notwithstanding the limited studies in Africa, the potential existence of Fasciola hybrids in Africa is real and might mimic scenarios in Asia, where parthenogenetic Fasciola exist in most Asian countries. In South Africa, aspermic F. hepatica and Fasciola sp. have been reported already, and Fasciola hybrids have been reported? in Chad and Egypt. Thus, the authors recommend future surveys using molecular markers recommended to identify Fasciola spp. and their snail intermediate hosts to demarcate areas of overlapping distribution where Fasciola hybrids and/or parthenogenetic Fasciola may occur. Further studies should also be conducted to determine the presence and role of P. columella in the transmission of Fasciola spp. in these geographical overlaps to help prevent parasite spillbacks.
巨片形吸虫和肝片形吸虫在非洲的出现已有充分记载;然而,与亚洲不同的是,关于该大陆上杂交种或孤雌生殖物种存在的信息匮乏。尽管如此,这些杂交物种可能具有有益特征,如扩大宿主范围和增强致病性。本研究为非洲存在片形吸虫杂交种的可能性提供了证据。使用搜索词和布尔运算符的组合,在PubMed、谷歌学术和科学Direct数据库中对1980年至2022年发表的文章进行了文献检索。在26个非洲国家记录到了片形吸虫物种,其中肝片形吸虫仅限于12个国家,而巨片形吸虫出现在24个国家,这是根据成年片形吸虫标本或虫卵的形态特征以及分子技术确定的。在11个国家报告了两种片形吸虫的共存情况。然而,仅在埃及和乍得证实了潜在片形吸虫杂交种的存在,在南非和津巴布韦也有疑似情况。这些是根据肝吸虫形态测量、精囊内精子评估以及分子技术确定的。在埃塞俄比亚、埃及、南非、坦桑尼亚和乌干达报告了中间宿主截口土蜗和纳塔尔萝卜螺的出现情况,这些地方报告了肝片形吸虫和巨片形吸虫的共存。在南非和埃及记录到自然感染巨片形吸虫的入侵型柱形伪琥珀螺。在津巴布韦,柱形伪琥珀螺感染了一种推测为孤雌生殖的片形吸虫。这表明入侵物种可能也在导致两种片形吸虫物种分布重叠,因为它可以传播这两种物种。尽管在非洲的研究有限,但非洲存在片形吸虫杂交种的可能性是真实的,可能与亚洲的情况类似,在大多数亚洲国家存在孤雌生殖的片形吸虫。在南非,已经报告了无精的肝片形吸虫和片形吸虫属物种,在乍得和埃及也报告了片形吸虫杂交种。因此,作者建议未来使用推荐的分子标记进行调查,以鉴定片形吸虫物种及其蜗牛中间宿主,划定可能出现片形吸虫杂交种和/或孤雌生殖片形吸虫的分布重叠区域。还应进一步开展研究,以确定柱形伪琥珀螺在这些地理重叠区域片形吸虫物种传播中的存在情况和作用,以帮助防止寄生虫回流。