Encephalitozoon intestinalis

Hinney, Barbara, Sak, Bohumil, Joachim, Anja & Kva ́ ̆ c, Martin, 2016, More than a rabbit's tale - Encephalitozoon spp. in wild mammals and birds, International Journal for Parasitology: Parasites and Wildlife 5 (1), pp. 76-87 : 79-80

2.1.3. Encephalitozoon intestinalis

E. intestinalis is the most prevalent Encephalitozoon species in humans and occurs worldwide. It also has been shown to occur in several, predominantly domestic, mammalian species (e.g. goat, pig, cattle, dog, donkey or gorilla). Zoonotic transmission was proposed to be an important source in human infections ( Bornay-Llinares et al., 1998; Graczyk et al., 2002; Didier, 2005; Mal̆cekov́a et al., 2010). In Slovakia especially domesticated pigs were the animals most often infected, with prevalences of 51% or more (Valen̆ćakov́a et al., 2006; Mal̆cekov́a et al., 2010). In birds E. intestinalis has only been reported sporadically ( Table 1). Genotypic variations in E. intestinalis were demonstrated ( Galvan et al., 2013) but have not been applied to broader surveys.

2.2. Diagnosis of Encephalitozoon spp .

Materials that can be used for microsporidial diagnosis are tissue samples, fluids such as urin as well as faeces and serum ( Garcia, 2002). When detecting spores in faeces only it cannot be excluded that these pathogens were just passaged in the gastrointestinal tract, e.g. via ingestion of infected mice ( Bornay-Llinares et al., 1998). However, long term shedding of spores indicates infection ( Sak et al., 2010).

Microscopical, molecular and serological methods are established for the detection of Microsporidia. Microscopy in combination with staining (e.g. Chromotrope 2R or fluorescence staining) allows to detect Microsporidia but not to differentiate species ( Garcia, 2002). Whereas electron microscopy can be used for species detection ( Garcia, 2002). Also detection of antibodies by serological techniques (e.g. indirect immunofluorescent-antibody testing (IFAT), enzyme-linked immunosorbent assay (ELISA), Western blotting; direct agglutination test (DAT)) is species specific ( Garcia, 2002). Serological tests have been primarily established for detection of E. cuniculi and IFAT and ELISA are routinely used for detection of this pathogen in rabbits where they are considered to be the most important diagnostic tool ( Künzel and Joachim, 2010). IFAT has been shown to be a sensitive and specific test for the detection of E. cuniculi in cats ( Künzel et al., 2014). The DAT was also described to be a useful test for detection of E. cuniculi in animals but might need some refinement ( Meredith et al., 2015). For some species, however, serology is not a reliable technique yet ( Garcia, 2002; Mathis et al., 2005). In addition these tests cannot distinguish between an active and past infection. The ability of detecting past infections however is also an advantage of serology and makes it a useful tool to access overall prevalence.

The Fluorescence in situ hybridization technique (FISH) is a fluorescence microscopy method targeting rRNA and allows simultaneous identification of Encephalitozoon spores to the species level ( Słodkowicz-Kowalska et al., 2006).

PCR is a highly sensitive and specific method. If followed by sequencing or restriction fragment length polymorphism techniques it allows to detect strains and genotypes. These PCR methods with subsequent genotyping yield valuable results for epidemiological studies as differentiation to the subspecies level allows assumptions on host specificity, origin, transmission pathways and spreading dynamics of the pathogen ( Xiao et al., 2001; Haro et al., 2005; Mathis et al., 2005; Ghosh and Weiss, 2009).