Moderator of 1 Session
Presenter of 3 Presentations
SCHISTOSOMIASIS IN LAKE MALAWI: SNAILS, SCHISTOSOMES AND UNRAVELLING THEIR SETTINGS (ID 437)
Despite ongoing control, schistosomiasis remains a public health problem in Malawi. At the southern end of Lake Malawi, Mangochi District, there have been significant changes in the epidemiology of schistosomiasis and ecology of freshwater snail hosts. In this presentation, I review progress made uncovering the burdens of male genital schistosomiasis, an unfolding outbreak of intestinal schistosomiasis and the detection of hybrid schistosomes.
Since November 2017 repeated human/snail surveys have taken place using a combination of parasitological, non-invasive imagery and molecular methods for infection detection and disease diagnosis. These include (non)standard egg-detection methods, use of portable ultrasonography and application of real-timePCR/DNA genotyping.
Male genital schistosomiasis in men, with or without HIV infection, can be common along the shoreline of the lake; some 10% present with schistosome eggs in semen and this prevalence increases to approximately 25% when real-time PCR detection methods are applied. Upon the initial unexpected finding of Biomphalaria pfeifferi within the lake, latter targetted surveys in local school children revealed upto 75% of children have intestinal schistosomiasis, alongside 25% with urogenital schistosomiasis. Hybrid schistosomes of Schistosoma haematobium-mattheei have been detected alongside a hitherto unknown species diveristy within local Bulinus africanus group snails.
The changing epidemiological patterns here in Malawi give a new setting to schistosome transmission cycles and need to devise better control strategies. In light of COVID-19 impacts, a good starting point is to increase frequencies of preventive chemotherapy and take a OneHealth approach.
SCHISTOSOMIASIS INTERVENTION AND ONE HEALTH APPROACH IN MALAWI (ID 1761)
I highlight our evolving narrative of collaborative multi-disciplinary studies of schistosomiasis along the shoreline of Lake Malawi. Commencing in November 2017, targeted epidemiological surveys were undertaken to assess and describe the burden of male genital schistosomiasis (MGS). Alongside these clinico-epidemiological studies on MGS, which also assessed an interplay with HIV, malacological surveillance was conducted. The latter was in attempt to shed light on contemporary parasite-snail transmission cycles within the lake. The research was primarily undertaken as PhD studies of Dr Seke Kayuni, a clinician and Mr Mohammad Al-Harbi, a malacologist. An initial unexpected finding was the discovery of Biomphalaria, a keystone host for Schistosoma mansoni. Shortly thereafter, we documented an emergence then later outbreak of intestinal schistosomiasis. Unusually, ectopic eggs of S. mansoni could be found in children’s urine. Upon more detailed inspection of schistosome urine- and stool-ova, various unusual egg morphologies were noted, being later identified as hybrid schistosomes of Schistosoma haematobium-mattheei and Schistosoma haematobium-bovis combinations. In April 2021, a 4-year joint investigator award was granted by The Wellcome Trust, UK to assess the extent of zoonotic schistosomiasis and tasked to collect necessary evidence if a OneHealth approach was now justifiable. In closing, I present our most recent evidence and describe how zoonotic schistosomiasis is now a challenge the current and future control in Malawi.
A COPROLOGICAL SURVEY OF SEMI-CAPTIVE BABOONS AT KNOWSLEY SAFARI PARK, UK REVEALS TRICHURIASIS, GIARDIASIS AND STRONGYLOIDIASIS (ID 427)
Knowsley Safari Park, Prescot, England maintains an unique semi-captive colony of some 250 olive baboons (Papio anubis). As part of the safari drive experience, visitors to the baboon enclosure can view animals up close, either within their own cars or in buses provided by the park. When vehicles stop, baboons often mount and defaecate upon vehicle surfaces. We therefore conducted an extensive coprological investigation, comparing stools obtained from vehicle surfaces versus those from baboon sleeping areas, to make a public health appraisal and animal welfare check.
Across four separate days of intensive faecal sampling, augmented with video analyses of vehicle entry-exit times and baboon-vehicle behaviours, a total of 645 stools were obtained and 2,662 vehicles observed. Faecal material was examined by standard parasitological methods inclusive of: coproscopy of Kato-Katz slides and charcoal cultures, and a rapid diagnostic test, namely QUIK-CHEK. The latter detects giardiasis and cryptosporidiosis.
Vehicles that spent more than 15 minutes inside the enclosure were 1.5 times more likely to be defecated upon than those spending less than 15 minutes inside. Overall prevalence of trichuriasis was 48.0% (95% CI: 41.8-54.2%), giardiasis was 37.4% (95% CI: 33.7-41.1%) and strongyloidiasis was 13.7% (95% CI: 12.0-15.4%). It was later judged, however, that QUIK-CHECK returned false positive results for no faecal cysts of Giardia could be seen upon formalin-ethyl acetate concentration. A sub-set of parasite material was subjected to DNA characterisation, confirming the presence of Trichuris trichiura and Strongyloides fuelleborni.
Our findings will be discussed in relation to future park management plans for this baboon enclosure.