Seroprevalence and coprological prevalence of liver fluke Fasciola hepatica in cattle and sheep from Santander department, Colombia.

Fasciola hepatica is a parasite with a worldwide distribution that affects several mammals, including humans, and is considered a public health problem. Therefore, the aim of this study was to determine the prevalence of Fasciola hepatica in humans, cattle and sheep, as well as to evaluate factors associated with the prevalence. A total of 185 serum samples from sheep, 290 from cattle, and 114 from humans were collected and processed using an in-house developed ELISA to detect IgG antibodies against F. hepatica. Additionally, 185 stool samples from sheep and 290 from cattle were examined using a Dennis sedimentation technique. Risk factors were analyzed using epidemiological surveys. The overall seroprevalence was 46.5% (86/185) in sheep, 32.5% (94/289) in cattle, and no humans tested positive for the infection. The coprological prevalence was 47.7% (86/180) in sheep and 33.7% (98/290) in cattle. Female gender and cattle living with alternate grazing management showed 2.5 and 6.5 times higher probability of infection, respectively. Bovines coexisting with sheep exhibited a higher risk of infection (odds ratio [OR]=4.3) compared to those without sheep. We concluded that F. hepatica in cattle and sheep has an endemic behavior, and therefore represents a problem of public health for rural communities.

Systematics and geographical distribution of Galba species, a group of cryptic and worldwide freshwater snails.

Cryptic species can present a significant challenge to the application of systematic and biogeographic principles, especially if they are invasive or transmit parasites or pathogens. Detecting cryptic species requires a pluralistic approach in which molecular markers facilitate the detection of coherent taxonomic units that can then be analyzed using various traits (e.g., internal morphology) and crosses. In asexual or self-fertilizing species, the latter criteria are of limited use. We studied a group of cryptic freshwater snails (genus Galba) from the family Lymnaeidae that have invaded almost all continents, reproducing mainly by self-fertilization and transmitting liver flukes to humans and livestock. We aim to clarify the systematics, distribution, and phylogeny of these species with an integrative approach that includes morphology, molecular markers, wide-scale sampling across America, and data retrieved from GenBank (to include Old World samples). Our phylogenetic analysis suggests that the genus Galba originated ca. 22 Myr ago and today comprises six species or species complexes. Four of them show an elongated-shell cryptic phenotype and exhibit wide variation in their genetic diversity, geographic distribution, and invasiveness. The remaining two species have more geographically restricted distributions and exhibit a globose-shell cryptic phenotype, most likely phylogenetically derived from the elongated one. We emphasize that no Galba species should be identified without molecular markers. We also discuss several hypotheses that can explain the origin of cryptic species in Galba, such as convergence and morphological stasis.

Lymnaeidae from Santander and bordering departments of Colombia: Morphological characterization, molecular identification and natural infection with Fasciola hepatica.

The Lymnaeidae constitute a family of freshwater gastropod molluscs whose diversity and ecology have been infrequently studied throughout Colombia. Some lymnaeid species act as intermediate hosts of trematode parasites, which are of great importance in both the veterinary and medical fields. Among trematode parasites, Fasciola hepatica is best known for being an important parasite of sheep and cattle for decades and causes significant economic losses in these livestock species. The main objective of this work is to identify the various species of lymnaeids that occupy different geographical regions of Santander and its bordering departments within Colombia. This will expand the knowledge of lymnaeid diversity in Colombia and provide further insight into their role in the transmission of F. hepatica. A total of 118 georeferenced sites between 126 m.a.s.l. and 3870 m.a.s.l. were sampled in Santander, Boyacá, Norte de Santander and Cundinamarca, respectively. Lymnaeid snails were identified according to the morphology of their shells and by several characteristics of their reproductive systems. Species identification was confirmed using DNA barcoding. Four lymnaeid species are reported in the study area: the native Galba cousini and three exotic species, Pseudosuccinea columella, G. truncatula and G. schirazensis. The four species were examined for natural infection with F. hepatica. Infected variants of the main snail host, G. cousini, were found in the Onzaga, Encino and Vetas municipalities of Santander, as well as in the Belén municipality of Boyacá. A second species, G. truncatula was also found naturally infected in Mutiscua municipality of Norte de Santander. The two other species, P. columella and G. schirazensis were found free of infection.