Abstract
BackgroudGiardia duodenalis and Cryptosporidium spp. are enteric protozoan causing gastrointestinal illness in humans and animals. Giardiasis and cryptosporidiosis are not formally considered as neglected tropical diseases, but belong to the group of poverty-related infectious diseases that impair the development and socio-economic potential of infected individuals in developing countries.MethodsWe report here the prevalence and genetic diversity of G. duodenalis and Cryptosporidium spp. in children attending rural primary schools in the Bahir Dar district of the Amhara Region, Ethiopia. Stool samples were collected from 393 children and analysed by molecular methods. G. duodenalis was detected by real-time PCR, and the assemblages and sub-assemblages were determined by multilocus sequence-based genotyping of the glutamate dehydrogenase and β-giardin genes of the parasite. Detection and identification of Cryptosporidium species was carried out by sequencing of a partial fragment of the small-subunit ribosomal RNA gene.Principal FindingsThe PCR-based prevalences of G. duodenalis and Cryptosporidium spp. were 55.0% (216/393) and 4.6% (18/393), respectively. A total of 78 G. duodenalis isolates were successfully characterized, revealing the presence of sub-assemblages AII (10.3%), BIII (28.2%), and BIV (32.0%). Discordant typing results AII/AIII and BIII/BIV were identified in 7.7% and 15.4% of the isolates, respectively. An additional five (6.4%) isolates were assigned to assemblage B. No mixed infections of assemblages A+B were found. Extensive genetic variation at the nucleotide level was observed within assemblage B (but no within assemblage A), resulting in the identification of a large number of sub-types. Cryptosporidium diversity was demonstrated by the occurrence of C. hominis, C. parvum, and C. viatorum in the population under study.ConclusionsOur data suggest an epidemiological scenario with an elevated transmission intensity of a wide range of G. duodenalis genetic variants. Importantly, the elevated degree of genetic diversity observed within assemblage B is consistent with the occurrence of intra-assemblage recombination in G. duodenalis.
Highlights
After pneumonia, diarrhoeal diseases remain the second most common cause of death among children under five globally, with 49.6% of the associated deaths occurring only in Africa [1]
G. duodenalis was detected by real-time PCR, and the assemblages and subassemblages were determined by multilocus sequence-based genotyping of the glutamate dehydrogenase and β-giardin genes of the parasite
In an attempt to improve and expand our current knowledge on the epidemiological and molecular situation of human giardiasis and cryptosporidiosis in Ethiopia, we present here a thorough assessment of the prevalence and genetic diversity of G. duodenalis and Cryptosporidium spp. in a large population of primary school children in a rural area of the Amhara Region
Summary
Diarrhoeal diseases remain the second most common cause of death among children under five globally, with 49.6% of the associated deaths occurring only in Africa [1]. The protozoan Giardia duodenalis and Cryptosporidium spp. are the main non-viral causes of gastrointestinal illness with diarrhoea in humans, infections by these pathogens are rarely fatal. G. duodenalis and Cryptosporidium infections may cause malabsorption and long-term nutritional deficit leading to stunting, growth and cognitive retardation, and failure to thrive during childhood and adolescence [4,5]. Due to their associated disease burden and considerable socio-economic consequences, both Giardia and Cryptosporidium joined the Neglected Disease Initiative launched by the World Health Organisation (WHO) in 2004 [6]. Interventions aiming to improve accessibility to clean water and latrines have been demonstrated very effective in reducing the prevalence of intestinal helminths and protozoa in endemic areas including Ethiopia [8,9,10]
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