Different hosts in different lakes: prevalence and population genetic structure of plerocercoids of Ligula intestinalis (Cestoda) in Czech water bodies.

Ligula intestinalis (Linnaeus, 1758) is a tapeworm parasite with a worldwide distribution that uses a wide variety of fish species as its second intermediate host. In the present study, we investigated the prevalence and population genetic structure of plerocercoids of L. intestinalis in five common cyprinoid species, roach Rutilus rutilus (Linnaeus), freshwater bream Abramis brama (Linnaeus), white bream Blicca bjoerkna (Linnaeus), bleak Alburnus alburnus (Linnaeus), and rudd Scardinius erythrophthalmus (Linnaeus), collected in six water bodies of the Czech Republic (Milada, Most, Medard, Jordán, Rímov and Lipno). Of the six study sites, the highest frequency of parasitism was recorded in Lake Medard (15%). The overall prevalence rate among the species was as follows: roach > rudd ≥ freshwater bream > bleak > white bream. Two mitochondrial genes (cytb and COI) were used to compare the population genetic structure of parasite populations using selected samples from the five fish species. The results of the phylogenetic analysis indicated that all populations of L. intestinalis were placed in Clade A, previously identified as the most common in Europe. At a finer scale, haplotype network and PCoA analyses indicated the possible emergence of host specificity of several mtDNA haplotypes to the freshwater bream. Moreover, pairwise Fixation indices (FST) revealed a significant genetic structure between the parasite population in freshwater bream and other host species. Parasite populations in roach not only showed the highest rate of prevalence but also depicted a maximum number of shared haplotypes with populations from bleak and rudd. Our results suggest that recent ecological differentiation might have influenced tapeworm populations at a fine evolutionary scale. Thus, the differences in prevalence between fish host species in different lakes might be influenced not only by the parasite's ecology, but also by its genetic diversity.

High Prevalence of Active and Latent Tuberculosis in Children and Adolescents in Tibetan Schools in India: The Zero TB Kids Initiative in Tibetan Refugee Children.

BACKGROUND: Tuberculosis (TB) prevalence is high among Tibetan refugees in India, with almost half of cases occurring in congregate facilities, including schools. A comprehensive program of TB case finding and treatment of TB infection (TBI) was undertaken in schools for Tibetan refugee children. METHODS: Schoolchildren and staff in Tibetan schools in Himachal Pradesh, India, were screened for TB with an algorithm using symptoms, chest radiography, molecular diagnostics, and tuberculin skin testing. Individuals with active TB were treated and those with TBI were offered isoniazid-rifampicin preventive therapy for 3 months. RESULTS: From April 2017 to March 2018, we screened 5391 schoolchildren (median age, 13 years) and 786 staff in 11 Tibetan schools. Forty-six TB cases, including 1 with multidrug resistance, were found in schoolchildren, for a prevalence of 853 per 100 000. Extensively drug-resistant TB was diagnosed in 1 staff member. The majority of cases (66%) were subclinical. TBI was detected in 930 of 5234 (18%) schoolchildren and 334 of 634 (53%) staff who completed testing. Children in boarding schools had a higher prevalence of TBI than children in day schools (915/5020 [18%] vs 15/371 [4%]; P < .01). Preventive therapy was provided to 799 of 888 (90%) schoolchildren and 101 of 332 (30%) staff with TBI; 857 (95%) people successfully completed therapy. CONCLUSIONS: TB prevalence is extremely high among Tibetan schoolchildren. Effective active case finding and a high uptake and completion of preventive therapy for children were achieved. With leadership and community mobilization, TB control is implementable on a population level.