Browsing by Author "Archer, Colleen Edith."

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A comprehensive investigation of existing sanitation helminth enumeration methods with the aim of producing an international standard.
(2022) Naidoo, Danica.; Archer, Colleen Edith.
TeHelminth testing in faecal sludge should be consistent so data are comparable. New faecal sludge treatments for on-site toilet technologies are constantly being developed in order for municipalities in developing countries to supply dignified alternatives to sewered systems that waste large amounts of potable water and require pumping to wastewater treatment works for centralised treatment. In order to ensure that these new, onsite toilet technologies adequately sanitise the faecal matter, helminth eggs are spiked into these systems to test inactivation according to the ISO-30500 standard for non-sewered sanitation systems (NSSS). A sensitive, standard helminth isolation and enumeration method, accredited to the ISO-17025 international standard for testing and calibration laboratories, is therefore required for application in laboratories globally. Internationally, laboratories and groups have used variations of the standard United States Environmental Protection Agency (USEPA) Method (2003), the Mexican Standard for Wastewater Analysis (2012), the Bailenger Method (1996) and the Pollution Research Group (PRG) Helminth Method (2017) previously used by the Water, Sanitation and Hygiene Research and Development Centre (WRDC) for helminth testing, and formed the foundation of this study. Conventional helminth methods can be broken down into five steps: washing and sedimentation of samples to separate eggs from larger particles, flotation using density gradients to separate eggs from heavier particles, centrifugation after both washing and flotation, extraction, that involves the use of a buffer and solvent combination to further separate organic material from eggs, and microscopic analysis. Some methods also include incubation that allows for egg-viability assessment. Every reagent used in these helminth methods was tested on Ascaris suum eggs for varying time intervals; ammonium bicarbonate and 7X® (a brand of ionic surfactant) performed best in terms of egg development and viability. Washing samples under pressure and no pressure were compared and the former produced the best egg recovery. Different flotation solutions were tested at different specific gravities, and zinc sulphate at specific gravity of 1.3 recovered the most eggs. Centrifugation speeds and times were tested after the washing and flotation steps, and 3000 rpm for 10 minutes and 2000 rpm for 15 minutes produced optimal egg recovery, respectively. Different extraction combinations were tested, and it was discovered that eggs were lost in this step. It was therefore recommended that extraction be removed from the method. Different wash solutions were then tested against various sample types to determine which resulted in the highest percentage egg recovery and which solutions facilitated easier microscopic analysis. Based on data from each experiment, a final SOP was produced for the new WRDC Helminth Method, that accommodates different sample types and egg viability assessment post incubation.st method.
Parasites of Rattus norvegicus trapped in Durban, eThekwini Municipality, South Africa.
(2018) Archer, Colleen Edith.; Appleton, Christopher Charles.; Mukaratirwa, Samson.
have acquired as they spread across the globe. This work narrows the gap in our knowledge of endoparasites carried by Rattus norvegicus in the port city of Durban, South Africa. The study was conducted over a one year period to include the wet and dry seasons, and rodents were trapped at 56 sites across four locations: central business district (CBD), harbour (HBR), informal settlements (IS) and urban/peri-urban (UPU) areas. The city’s Vector Control Division conducted the trapping using custom-made live traps. Three hundred and seventy nine R. norvegicus were caught, plus by-catches of 10 R. rattus and 11 Mastomys natalensis. Rodents were humanely euthanased, blood samples drawn, all ectoparasites collected for a parallel study, various body measurements and mass recorded, then they were dissected, their organs removed and faeces collected. Organs were individually processed, parasites removed and preserved in 70% ethanol prior to identification. Faeces were collected in 10% formal saline for parasite egg and cyst identification. Parasites of public health importance recovered from R. norvegicus were: Trypanosoma lewisi (22.8%) from blood; Moniliformis moniliformis (9.5%), Hymenolepis diminuta (17.2%), H. nana (0.8%) and Gongylonema sp. (25.3%) from the small intestine; Calodium hepaticum (2.6%) from the liver and Angiostrongylus cantonensis (15.3%) from the heart and lungs. Serological testing for Toxoplasma gondii yielded a prevalence of 11.2%. Parasite ova mechanically transmitted in the rodents’ faeces, and a potential infection risk for humans, were Ascaris sp. (4.8%), Taenia sp. (0.3%), Schistosoma mansoni (0.3%), Calodium hepaticum (0.8%), Ascaridia galli (0.5%) and Toxocara sp. (0.3%). Xenopsylla cheopis, Polyplax spinulosa, Laelaps lamborni and L. echidnina were investigated as drivers of T. lewisi infection. Rats infected with T. lewisi and X. cheopis were more prevalent at CBD and HBR, and juveniles were most frequently affected. Trypanosome infections were positively associated with fleas, negatively associated with lice, and not associated with mites. Extrinsic and intrinsic interactions between helminths of the gut were examined and location and rat age were found to be the most significant drivers. The helminths were: Gongylonema neoplasticum, Protospirura muricola, Moniliformis moniliformis, Hymenolepis diminuta, H. nana, Nippostrongylus brasiliensis, Strongyloides spp., Heterakis spumosa, and Syphacia muris. Taenia taeniaformis was most prevalent and abundant at IS, in males, and in rats as they aged. Trichosomoides crassicauda was most prevalent and abundant at CBD, HBR and UPU, in males and in rats as they aged (no pups were infected). Common gut protozoans were identified and reported, as were the eggs voided by rats unrelated to their helminth infections. The city centre offers harbourage and abundant food for rats, and suitable habitats for the successful breeding of arthropod vectors of some of these parasites, making it an area of high transmission and a potential public health risk.