Taenia solium, Taenia saginata, Taenia asiatica, their hybrids and other helminthic infections occurring in a neglected tropical diseases' highly endemic area in Lao PDR

Abstract

Most part of Southeast Asia is considered endemic for human-infecting Taenia tapeworms; Taenia solium, T. saginata, and T. asiatica. However, until now there was no report of the occurrence of human cases of T. asiatica in Lao PDR. This study, conducted in Savannakhet Province, Lao PDR, microscopically examined a total of 470 fecal samples by Kato Katz method and found 86% of people harboring at least one helminth. Hookworms were detected in 56% of the samples besides Opisthorchis like eggs (42%), Trichuris trichiura (27%), Ascaris spp. (14%), and Taenia spp. (4%) eggs. Serology for cysticercosis showed 6.8% positives with results varying from 3% to 14.3% in Ethnic School students and Kalouk Kao village respectively. Species-specific PCR targeting mitochondrial DNA (mtDNA) of 28 tapeworms, recovered from 16 patients, revealed T. solium (n = 2), T. saginata (n = 21), and T. asiatica (n = 5). Two patients were confirmed to be coinfected with T. saginata and T. asiatica, indicating the endemicity of the 3 human Taenia in Lao PDR. However, nucleotide sequencing of a nuclear DNA gene, DNA polymerase delta (pold) revealed that all the tapeworms identified as T. asiatica using mtDNA had T. saginata type allele at pold locus, demonstrating that they are not “pure T. asiatica” but the hybrid descendants between the two species, confirming the wide distribution of hybrids of T. saginata/ T. asiatica in Southeast Asia. The high prevalence of several helminthic NTDs in east Savannakhet area even with conventional control measures indicates the importance to establish wide and multifaceted health programs to sustainably improve the quality of life of the populations living in these communities.

Nuclear and kinetoplast DNA analyses reveal genetically complex Leishmania strains with hybrid and mito-nuclear discordance in Peru

“…Following these early discoveries, methods for assaying numerous individuals for their nuclear genotype became more widely available to researchers and, subsequently, the number of cases increased markedly in animals such as mammals, birds, reptiles, amphibians, fish, and insects [ 37 ]. More recent studies revealed that mito-nuclear discordance occurs in helminth parasites [ 40 – 44 ].…”

A co-infection case report of Taenia saginata in a patient with subclinical clonorchiasis confirmed by the combination of diagnostic tools

“…Cho et al successfully used cox1 to distinguish between T. saginata and T. asiatica [11]. Recently, studies conducted in China and Lao People’s Democratic Republic reported that hybridization between the three Taenia species cab iccyr, based on sequencing nuclear and mitochondrial genes [19, 20]. In our case, as we did not observe uterine structures or ova in the proglottids in our patient’s stool sample, these proglottids were likely immature.…”

Odds, challenges and new approaches in the control of helminthiasis, an Asian study

“…The important helminthes are soil transmitted helminthes (STHs), foodborne helminthes and schistosomes occurring mostly in areas of low-income inhabitants with sub-standard sanitation. Interestingly, people are aware of parasitic disease; however, there is a sentiment that the infection is unavoidable and the treatment uncertain, thus leading to high rates of helminth infection and heavy worm burden (Sato et al, 2018a).…”