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* Corresponding authors. Faculty of Veterinary Science, University of Sydney, New South Wales, Australia. E-mails: vmor0718@uni.sydney.edu.au ; jan.slapeta@sydney.edu.au
INTRODUCTION
A number of common, medically significant parasitic diseases are, ironically, neglected diseases (Van der Pol, 2007). Within this group are diseases caused by protozoan flagellates that reside extracellularly and in oxygen-deprived environments (anaerobic) within their hosts. These include enteric human parasites such as Giardia duodenalis, Entamoeba histolytica, Cryptosporidium and the urogenital track parasite, Trichomonas vaginalis. Pathogenesis of enteric parasites results from physical parasite damage to the intestinal mucosal membrane causing malabsobtion, and mild-to-severe chronic gastroenteritis associated with increased secretion that induce diarrhoea and reduced growth in children (Buret, 2008; Raza et al. 2013; Checkley et al. 2015). In addition, Entamoeba infections can advance to more serious manifestations including acute necrotizing colitis that mask other underlying pathogenesis (Petri and Singh, 1999; Bercu et al. 2007). On the other hand, T. vaginalis causes physical damage to the genital mucosa of female hosts resulting in severe vaginitis and facilitates the spread of the HIV virus (Wegayehu et al. 2013; Fletcher et al. 2014). The epidemiology of neglected protozoan parasitic diseases predominantly correlates with socio-economic attributes of developing countries with poor sanitary conditions (Raza et al. 2013; Betancourt et al. 2014; Fletcher et al. 2014; Checkley et al. 2015). A 2014 World Health Organisation report estimated that the global disability-adjusted life year (DALY) for diarrhoeal disease in low and middle income countries, expressed as the number of years lost due to illness or death, was 33 793 DALYs due to inadequate water supply (WHO, 2014). Cryptosporidium, a significant cause of moderate-to-severe diarrhoea, was ranked as the second most significant agent of diarrhoeal disease in sub-Saharan African and south Asia by the Global Enteric Multicentre Study (GEMS) (Kotloff et al. 2013). While GEMS failed to associate Giardia as a significant cause of severe diarrhoea (Kotloff et al. 2013), parasite burden is clearly prominent in countries of lower socio-economic status. For instance, a recent study conducted in Ethiopia revealed 13·8% of clinical samples were Giardia-positive, while in the more developed state of New South Wales in Australia, 1% of clinical samples examined were Giardia-positive (Betancourt et al. 2014; Fletcher et al. 2014). As the most common, non-virally sexually...