Strengthening capacity for food surveillance of human pathogenic microsporidian spores on pig farms in Makeni, Sierra Leone

Following the detection of microsporidia in animal faeces collected from different farms in Bombali District, Sierra Leone (SL), in April 2019, we began implementing a multi-stage project to build medical parasitology capacity at the University of Makeni (UniMak, SL) to address potential future risks from these opportunistic parasites. UniMak academics introduced novel practicals for the detection of microsporidia in different BSc Public Health modules in 2020/21 and followed a blended approach using the e-Parasitology package (http://parasitology.dmu.ac.uk/). Students processed thirty-six fresh stool samples from pigs provided by the SL Department of Agriculture and Food Security from a nearby farm (Makeni) in 2021. Students prepared smears in a class II biosafety cabinet and learned to perform trichrome staining for spore detection. Further fresh faecal samples were collected from four pigs in summer 2022 to investigate temporal variation.

The students showed a high level of confidence as soon as they entered the laboratory. They were able to carry out all the different practical steps quickly. A high level of accuracy was observed in the students' detection of spores present in 14/36 (38.8%) of the stool smears monitored, which would be consistent with the prevalence of microsporidia previously detected by our group (7/12; 58%) using SYBR Green real-time PCR on 12 pig stool samples collected in 2019. One of the samples collected in 2022 was positive for spores of the genus Encephalitozoon. In addition, structures compatible with Encephalitozoon spp. were observed in another pig. These results are similar to those observed in 2019, suggesting a moderate circulation of Encephalitozoon spp. in the monitored farms, highlighting a potential risk to the Sierra Leonean population. The different phases and strategies used seem to have been successful in building capacity to prepare future UniMak professionals to manage microsporidian infections in Sierra Leone.