Conference Agenda

Schistosoma japonicum, the Asian schistosome, is a zoonotic parasite that infects humans and more than 40 species of domestic animals. It is a principal causative agent of schistosomiasis, a neglected tropical disease affecting 240 million people globally. In endemic regions, bovines are major reservoirs responsible for up to 75-90% of environmental egg contamination that perpetuate transmission. Current control efforts rely heavily on chemotherapy with Praziquantel, though effective at reducing worm burdens, does not prevent reinfection with risk of developing drug resistance if used solely. These limitations highlight the urgent need for integrated strategies to achieve sustainable control. Mathematical modelling has indicated that coupling chemotherapy with an effective transmission-blocking vaccine (TBV) could achieve elimination of S. japonicum within a decade. In this context, my PhD project seeks to develop an mRNA TBV by evaluating parasite-derived proteins with demonstrated immunogenicity and protective potential. Preliminary murine trials demonstrated significant reductions in worm and egg burdens, as well as alleviation of liver pathology. The integration of such promising antigens in a multivalent mRNA vaccine represents a rational strategy to maximize protection and durability of response and combined with control measures offers a promising pathway toward sustainable schistosomiasis control and improved global public health outcomes.

The prevalence and diversity of intestinal parasites in Papua New Guinea (PNG) and their potential impact as co-morbidities on endemic infectious diseases, such as tuberculosis (TB), remain poorly understood. This cross-sectional study provides an updated assessment of intestinal parasites (helminths and protozoa) in a TB-endemic rural PNG community. Participants were recruited from Balimo District Hospital, with stool and blood samples collected in June 2019 and January 2020. Faecal specimens (n=164) were examined by microscopy and qPCR, and plasma samples (n=121) were tested for Strongyloides-specific IgG antibodies using a commercial ELISA

Overall, 95.1% of participants had at least one type of intestinal parasite. Intestinal protozoa were detected in 85.4% of participants, most commonly detected were Blastocystis spp. (77.4%), Entamoeba hartmanni (29.3%), E. coli (23.3%), Dientamoeba fragilis (16.5%) and E. polecki (12.8%). Helminths were detected in 65.9%, predominantly Necator americanus (44.5%), Ascaris lumbricoides (37.8%) and Strongyloides spp. (17.7%). Polyparasitism was common, with 44.5% harbouring multiple protozoan and 31.1% infected with two or more helminths. These findings demonstrate a high burden and diversity of intestinal parasites in rural PNG. Whether co-infection with these parasites impacts the clinical outcome TB remains to be determined.

Insecticide treated nets (ITNs) are the most widely used mosquito control tool. To ensure efficacy and quality, ITN products undergo a prequalification process, with any changes to prequalified products to be reported to the World Health Organization. As a result, recipients can expect to receive products exhibiting consistent physical and insecticidal properties. A durability study showed that Yahe ITNs distributed in Papua New Guinea (PNG) in 2021 did not retain insecticidal efficacy for longer than several months. ITNs are frequently exposed to elevated temperatures during transport and storage and throughout their lifespan in the tropics. To better understand the potential impact of elevated temperature on insecticidal efficacy of Yahe, and to investigate why ITNs failed insecticidal efficacy tests after 6 months in PNG, Yahe ITNs were stored at elevated temperatures and evaluated using cone bioassays. Results revealed diverging physical and insecticidal properties of ITNs sampled from a single batch with ITNs exhibiting differences in colour, mesh size, weave, and insecticidal efficacy. Furthermore, ITNs exposed to 35- 50°C exhibited significantly decreased insecticidal efficacy. This study highlights inconsistencies in basic product properties of Yahe LN ITNs that are apparently not controlled or reported, and the importance of assessing current products for temperature-stability.

Strongyloidiasis, “the most neglected tropical disease”, caused by the helminth Strongyloides stercoralis, is a major global concern. It can persist life-long following infection, unless treated, due to the auto-infective lifecycle. Infection can be fatal, particularly among patients with immunosuppression. Despite health risks, knowledge surrounding strongyloidiasis burden and diagnostics remains limited.

The World Health Organization (WHO) advocates for strongyloidiasis’ inclusion in parasite control programs; however, with no population-based diagnostic tests and no large-scale surveys, large-scale treatments are not being provided. Global strongyloidiasis targets are off-track, and millions of people suffer from preventable debility.

Microscopy is a mainstay of population-based helminth surveys. Artificial intelligence (AI) improvements have led to AI-guided microscopy. A novel automated AI-based platform that images and digitises samples on standard microscopy slides to detect and quantify parasitic infections recently showed increased sensitivity and rapidity over human slide readers.

We are developing the first AI model for detecting S. stercoralis using larvae from lab and clinical samples, supporting AI training. We are trialling different preparations for Strongyloides spp. detection, and will undertake field validation in North East Arnhem Land. Our expected outcome is the first field-validated, AI-based S. stercoralis population-level diagnostic test, to allow population treatment programs to commence.