Fascioliasis due to Fasciola hepatica (Linnaeus, 1758) is an endemic disease on the Northern Bolivian Altipiano, where human prevalences and intensities arc the highest known, sheep and cattle are the main reservoir hosts, and pigs and donkeys the secondary ones. Investigations were carried out to study the viability of metacercariae experimentally obtained from eggs shed by naturally infected Altiplanic sheep, cattle, pigs and donkeys. A total of 157 Wistar rats were infected with doses of 5, 10, 20 and 150 metacercariae. Metacercariae aged for different number of weeks were used to analyse the influence of age on their viability. The number of worms successfully developed in each rat was established by dissection. Results obtained show that metacercarial infectivity is dependent upon storage time, being lower when metacercariae arc older. The maximum longevity is 31 weeks using doses of 20 metacercariae per rat and 48 weeks with 150 metacercariae per rat, although in the latter case only a very low percentage of worms is recovered. Age-related infectivity of metacercariae from Altiplanic F. hepatica does not significantly differ from that of the liver fluke in lowlands of other countries. Concerning the influence of the isolate according to host species, results indicate that metacercarial viabilities of pig and donkey isolates are similar to the viabilities of metacercariae of sheep and cattle isolates. Thus, pig and donkey have a high transmission potential capacity concerning this aspect. This fact is of great importance for the control of human and animal fascioliasis in this highly endemic zone.
Human material of an African specimen of Bertiella studeri (Blanchard, 1891 ), a typical intestinal ceslode of monkeys, is described. Mature, postmaturc and gravid proglottides, and eggs, previously inadequately figured, are illustrated and photographed. The description of the species agrees with that provided by Stunkard (1940). A comparative study with other descriptions of the species is made in an attempt to clarify previous findings. The morphological differences reported in various earlier descriptions of the species suggest that B. studeri should be regarded as a “B. studeri species complex”. Improvements are required in the descriptions of new future findings in order to clarify the specific diagnosis of human bertiellosis. Evidence suggests that a generalised diagnosis exclusively based on egg size and geographical distribution is insufficient to differentiate B. studeri and Bertiella mucronata (Meyner, 1895), or additional species may be affecting humans.