Toxoplasma gondii is a protozoan with a worldwide distribution, in warm-blood animals, including humans. Local conditions and environmental disturbances may influence transmission dynamics of a zoonotic agent. This study evaluates the epidemiology of T. gondii based on toxoplasmosis prevalence in two populations of cats living in distinct urbanization conditions in Rio de Janeiro, Brazil. Among 372 domestic cats sampled, 265 were from a public shelter located downtown Rio and 107 from a relatively preserved wild environment in a residential area. Sera and eluates from dried blood spots were tested for detection of IgG antibodies against T. gondii by modified agglutination test (MAT). Antibodies to T. gondii were detected in 32/265 (12.08%) animals from the public shelter and in 4/107 (3.74%) cats from the residential area. Identical results were observed for sera and eluates. Filter paper provides a reliable accurate alternative storage option when conditions of sample collection and transportation in the field are unfavorable. The significantly lower prevalence in the residential area is discussed in terms of environmental, biological and behavioral features.

High prevalence of Fasciola hepatica infection (>70%) was noted during several outbreaks before the 2000s in several French farms where Galba truncatula is lacking. Other lymnaeids such as Lymnaea fuscus, L. glabra and/or Radix balthica are living in meadows around these farms but only juvenile snails can sustain complete larval development of F. hepatica while older snails were resistant. The low prevalence of infection (<20%) and limited cercarial production (<50 cercariae per infected snail) noted with these juveniles could not explain the high values noted in these cattle herds. As paramphistomosis due to Calicophoron daubneyi was not still noted in these farms, the existence of another mode of infection was hypothesized. Experimental infection of several successive generations of L. glabra, originating from eggs laid by their parents already infected with this parasite resulted in a progressive increase in prevalence of snail infection and the number of shed cercariae. The aim of this paper was to determine if this mode of snail infection was specific to L. glabra, or it might occur in other lymnaeid species such as L. fuscus and R. balthica.

Experimental infections of 1-mm high snails using three populations of Lymnaea (L. glabra, L. ovata and L. truncatula) and a cattle strain of Fasciola hepatica miracidia were carried out under laboratory conditions to determine if the snail species had an effect on the number of free rediae, their growth, and cercarial productivity in relation to each redial category (R1a, R1b, R2a, or R2b/R3a). The total number of rediae ranged from 6.4 to 7.5 per snail. The mean body length of rediae varied from 1–1.2 mm (R1a) to 0.3–0.4 mm (R2b/R3a). The width of the intrapharyngeal lumen also varied from 26.0–38.8 μm to 3.0–4.2 μm, respectively. The redial category had a significant effect on both measurements, whereas snail species only had a significant influence on body length. The mean number of cercariae produced by all living rediae at day 49 post-exposure ranged from 63.0 in L. glabra to 87.2 in L. truncatula. In L. ovata and L. truncatula, 55.8% and 58.6% of cercariae, respectively, were produced by R2a rediae, whereas 53.9% of cercariae in L. glabra were formed by the R1b rediae. When young snails were infected with F. hepatica, the species of snail had an effect on the number of living rediae, their length and their cercarial productivity.

Parasitological investigations on ruminal paramphistomosis were carried out in 2033 cattle over a 14-month period in three Algerian slaughterhouses to determine the prevalence and intensity of this disease. The prevalence of infection varied from different slaughterhouses (1.2% at El Khroub, 7.5% at Ferdjioua and 12.1% at Jijel). The worm burden was significantly higher in cattle from El Khroub than for those slaughtered in the other two sites (a mean of 984.1 parasites compared with 87.5 and 140.7 at Jijel and Ferdjioua, respectively). No significant correlation between prevalence, intensity of infection and age of cattle was noted. Overall, females were significantly more infected than males, whereas the sex of animals was independent of worm burdens recovered in slaughtered cattle. The climatic conditions of provinces in which the slaughterhouses were located (a more temperate climate for Jijel and semiarid conditions for the other two provinces) may partly explain variations noted in prevalence and intensity of infection. The present results will contribute to our understanding of the epidemiology of Paramphistomum daubneyi infections in north-eastern Algeria.