Conference Agenda

Intestinal parasitic diseases remain a significant public health burden globally. There is an increasing need for a versatile, sensitive, and cost-effective mechanism for near-elimination and post-elimination surveillance systems for population-wide. Traditional faecal sampling from individuals across large populations is expensive, intrusive, and impractical. Wastewater-based epidemiology is a population-level surveillance tool.

A series of multiplex qPCRs was chosen to detect common parasites of public health importance. Limits of detection and specificity for human-infecting species were determined. Influent wastewater from an urban treatment plant was spiked with a known concentration of cysts, eggs, and larvae of the target parasites (Giardia duodenalis, Ascaris lumbricoides, Trichuris trichiura, Necator americanus) and processed using three concentration protocols. DNA was extracted using Powersoil Pro (Qiagen) kits, and four Taqman multiplex qPCRs were performed, including human DNA and internal amplification control targets.

The diagnostic qPCRs chosen demonstrated high sensitivity and specificity. Wastewater application of the multiplex was successful. Initial results indicate that centrifugation or sieve selection prior to DNA extraction was necessary to detect parasitic DNA in wastewater samples. Processing raw wastewater or wastewater sediments proved ineffective.

This work establishes a methodological basis for implementing wastewater-based population-level surveillance for soil-transmitted helminths and intestinal protozoa.

A 71-year-old man was found incidentally to have a crusted lesion on the floor of the nose during resection of a pituitary tumour. Microscopy showed an inflammatory infiltrate with ovoid cells, staining positive with PAS and silver raising concern for a free-living amoeba (FLA). However, multiplex PCR for Acanthamoeba species, Balamuthia mandrillaris and Naegleria fowleri was negative. There was no clinicoradiological evidence of meningoencephalitis. We reviewed the biology, clinical features and diagnosis of FLA infections.

Amongst 26 cases of rhinosinusitis, Acanthamoeba species were implicated in 25 and Entamoeba histolyticain one. The average age of patients was 43 mostly males. 11 patients died. Histopathology was used for diagnosis in 21 cases, PCR in 7. In two cases both were utilised. Culture was used in 1 case. All Acanthamoeba cases were associated with immunosuppression; HIV (17), CLL and solid organ transplant (3), haematopoietic stem cell transplant (1) and one hypogammaglobulinaemia.

Our asymptomatic case represents a dilemma, without literature to guide management in an incidental finding of amoeba in histopathological specimen especially after breach of the nasal mucosa for biopsy. FLA are ubiquitous and are found as carriers in the nose of volunteers. Disease likely affects immunosuppressed patients with compatible inoculation route.