Prevalence and molecular identification of Trichinella species isolated from wildlife originating from Limpopo and Mpumalanga provinces of South Africa

Abstract

Trichinella species are widely distributed on all continents with the exception of Antarctica, although the full spectrum of Trichinella species found in sub-Saharan African countries, and their hosts, has not been fully documented. This study was conducted to determine the prevalence of Trichinella in wildlife from the Greater Kruger National Park (GKNP) and adjacent areas located in the Limpopo and Mpumalanga provinces of South Africa, and to identify the species and/or genotypes of Trichinella larvae isolated from muscle tissues, using molecular techniques. A review of Trichinella spp. and their wildlife hosts reported during 1964-2011 was also conducted and the results were compared with our current study. Ninety samples representing 15 mammalian, two bird and three reptile species were screened for Trichinella infection during 2012-2016, using artificial digestion. Isolates detected were identified using a multiplex polymerase chain reaction (PCR) amplification of the internal transcriber spacers ITS1 and ITS2, and expansion segment V (ESV) regions of ribosomal DNA, followed by molecular analysis of the sequences. Twenty samples from seven wildlife species were positive for Trichinella spp. larvae, with an overall prevalence of 21.1% (20/90). The prevalence was higher in carnivores (18.9%, 18/90) than in omnivores (2.2%, 2/90). Analysis of sequences showed that eight of the isolates - two from spotted hyaena (Crocuta crocuta) (2/8), three from lion (Panthera leo) (3/13), one from leopard (Panthera pardus) (1/6), one from small spotted genet (Genetta genetta) (1/2) and one Nile monitor lizard (Varanus niloticus) (1/2) - conformed to Trichinella zimbabwensis. One isolate from a hyaena was grouped under the encapsulated species clade comprising T. nelsoni and genotype Trichinella T8 reported to be present in South Africa. This is the first report confirming natural infection by T. zimbabwensis in hyaena, leopard, genet and Nile monitor lizard, adding to the body of knowledge on the epidemiology of Trichinella infections in the Greater Kruger National Park of South Africa. Ten Trichinella-like larval isolates recovered after digestion from four wildlife species in this study (2012-2016) revealed inconclusive results due to DNA degradation resulting from poor storage or too few larvae for analysis, in comparison to 20 unidentified isolates from five wildlife species during the 1964-2011 period.

Epidemiology and hypothetical transmission cycles ofTrichinellainfections in the Greater Kruger National Park of South Africa: an example of host-parasite interactions in an environment with minimal human interactions

“…In the GKNP, the prevalence of T. nelsoni in lions and hyaenas was reported to be 3/98 (3.06%) and 0/26 (0%), respectively [54]. It is important to note that the majority of these isolates (11/21) and (14/17) found in lions and hyaenas respectively, were not identified to species level [54] and thus the actual prevalence in GKNP could be higher than reported.…”

“…Trichinella species reported in the GKNP From the beginning of Trichinella surveillance studies in South Africa in 1964 to the end of 2016, at least two species and one genotype have been confirmed across six mammalian and two reptilian hosts from the GKNP [38,40,43,54,79]. Trichinella-like infections have additionally been reported in six other mammalian hosts, but species confirmation of the parasite was not possible [43,54,100,101]. The unidentified isolates, for the most part, were generally believed to be one or more of the parasite species known to circulate in the area.…”

“…The unidentified isolates, for the most part, were generally believed to be one or more of the parasite species known to circulate in the area. A Trichinella-like infection has also been reported in a Marsh owl (Asio capensis), possibly suggesting the existence of an additional Trichinella specie not known to occur on the African continent or a different tissue-dwelling nematode/larva not related to Trichinella [54] (Table 2).…”

“…At least four species of Trichinella are known to circulate in sub-Saharan Africa, including T. nelsoni, Trichinella T8, T. britovi and T. zimbabwensis [53]. Of the four Trichinella species known to circulate in this region, all except T. britovi, have been reported in the GKNP [53,54]. Mukaratirwa et al [53,54] confirmed lions (Panthera leo) and hyaenas (Crocuta crocuta) to be the major reservoirs for Trichinella infections in the Greater Kruger National Park (GKNP), based on reported prevalence data.…”

“…However, of late, Trichinella spp. infections have been confirmed in at least six mammalian and two reptile species from the GKNP [38,40,43,54,79] as well as Trichinella-like infections in at least six additional mammalian hosts [43,54,100,101]. Despite the diverse host range and the fact that South Africa has the highest reported prevalence of Trichinella in sub-Saharan Africa [54], no human cases have been reported from South Africa to date.…”