Population dynamics of intermediate snail hosts of Fasciola hepatica and some environmental factors in San Juan y Martinez municipality, Cuba

Abstract

In Cuba fasciolosis is regarded as one of the most important parasitic diseases with both economical, showing high prevalence in cattle (Mauri 1972, Verdecia et al. 2001) and medical significance (Kourí 1948, Brito et al. 1987, Millan et al. 2000. This disease is caused by the liver fluke Fasciola hepatica, which needs a lymnaeid snail as intermediate host to complete its life cycle. Only two lymnaeids are known to be present in Cuba: Fossaria cubensis and Pseudosuccinea columella. Both species can host larvae of the trematode, but only the former has been found naturally infected in the island. Currently, only the curative aspect of the disease is taken into account by a chemotherapy treatment of the final host (Ritchter et al. 1999, Millan et al. 2000. No integrated program aiming at stopping or at limiting the transmission of the parasite, associating the control of intermediate snail hosts to other control strategies is currently carried out at the national level.The development of an effective strategy of integrated control, with the precondition of a good knowledge on the epidemiology of this parasitosis requires including, among other things, the study of population dynamics of intermediate hosts and its relation to environmental factors. This study had as objective to determine the variations of the abundance of F. cubensis and of P. columella as well as their relationship with various factors of the environment such as certain physico-chemical parameters of the water, the snail diversity and the abundance of other snail species. MATERIALS AND METHODSThe field work was carried out in the municipality San Juan y Martinez, located south of Pinar del Rio province. Recently, high cattle infections by F. hepatica were referred in this locality as well as two human cases (which appear in the files of the local center of hygiene and epidemiology). Five sampling sites were selected in various water collections: (A) a culvert of residual waters from houses located close to the dispensary of the city; (B) a site on the river which crosses the city; (C) a drainage canal from a vegetable plantation located in the city; (D) a site on a small river outside the city and close to the small village of El Cañón; and (E) a small pond that originated and is fed by the water of an irrigation system. The sites A, C, and D are in or close to the city, whereas the sites B and E are more rural and with no or a little contact with the local population. Sampling took place once a month during one year (from April 2000 to May 2001)The species abundance was estimated by collecting snails using a sieve and forceps, always by the same collector during 15 min; the abundance was then measured as the number of snails collected for each 15-min sampling. The snails were carried to the laboratory in plastic boxes and then identified and counted. The following environmental variables were measured: water temperature, pH, total hardness, nitrites, and nitrates. The snail diversity at each sampling was estimated by the index of Shannon and Wea...

A multiplex PCR for the detection of Fasciola hepatica in the intermediate snail host Galba cubensis

“…However, its presence in some regions of North (Kaplan et al, 1997) and South America (Bargues et al, 2011;Medeiros et al, 2014), where it co-exist with other snail hosts complicates the epidemiological scenario of fasciolosis. Several investigations have been conducted, mainly in Cuba where fasciolosis is endemic in livestock, regarding the role of G. cubensis in F. hepatica transmission (Vázquez et al, 2014), its ecology and distribution (Cañete et al, 2004;Vázquez et al, 2009), and control strategies for its management (Perera et al, 1991). A DNA probe assay was developed and validated in field-collected G. cubensis (Kaplan et al, 1997) but the complicated and time-consuming technique of DNA hybridization could limit its application during large-scale surveys of F. hepatica infection in snails.…”

Evaluation of Some Pollution at Manzala Lagoon: Special Reference to Medical Importance of Mollusca in Egypt

“…However, the importance of different ecological factors vary significantly from one ecological zone to the other and even from one water body to the other, suggesting local investigations to identify important factors in each zone or water bodies [2][3][4][5]. Many studies concerned with the ecology and population dynamics of gastropods which play an important role in transmitting diseases to man and his livestock have been conducted by Abd El-Malek [6]; Dazo et al [3]; Barbosa and Barbosa [7]; Utzinger et al [8]; Kloos et al [9]; Karimi et al [10]; Cañete et al [11] Kazibwe et al [12] and Mostafa [13]. These studies have led to general opinion; that the development of an effective strategy of integrated control requires the study of population dynamics of the intermediate hosts and its relation to environmental factors.…”

Fasciolosis aguda: presentación de un caso de Cuba

“…Para que ocurra la transmisión de esta parasitosis es necesaria la presencia en tiempo y espacio de los animales infectados, los moluscos dulceacuícolas que actúan como hospederos intermediarios y el hospedero susceptible. Galba cubensis y Pseudosuccinea columella, dos especies de la familia Lymnaeidae, son los hospederos intermediarios de esta parasitosis en Cuba [4][5][6] . El ciclo de vida del parásito es complejo.…”

“…Para que embrionen es imprescindible el contacto de los huevos con agua dulce a temperaturas que oscilen entre los 22-26 °C. Luego de una a dos semanas el huevo se rompe y da paso a la primera forma larvaria (miracidium) que necesita, para continuar su ciclo natural, la presencia de moluscos dulceacuícolas que actúan como hospederos intermediarios 5 . En los hospederos intermediarios se producen estadios larvarios sucesivos que finalmente culminan con la liberación de las cercarías que nadan libremente hasta alcanzar plantas acuáticas, cortezas de árboles y otras superficies lisas o quedar suspendidas en aguas poco profundas donde pierden su cola y se transforman en metacercarias (blanquecinas, redondeadas y cubiertas de pared gruesa) que constituyen la forma infectante de la parasitosis 1 .…”