Volume 52, Issue 1

Chagas disease, caused by the obligate unicellular parasite Trypanosoma cruzi, presents itself in a diverse collection of clinical manifestations, ranging from severe, fatal heart and digestive tract pathologies to unapparent or minor alterations that do not compromise survival. Over the years, a number of mechanisms have been proposed to explain the pathogenesis of chagasic tissue lesions, all of which have faced some criticism or been received with skepticism. This article excludes the autoimmunity hypothesis for Chagas disease because it has been extensively reviewed elsewhere, and summarizes the various alternative hypotheses that have been advanced over the years. For each of these hypotheses, an outline of its main tenets and key findings that support them is presented. This is followed by the results and comments that have challenged them and the caveats that stand on their way to wider acceptance. It is hoped that this writing will draw attention to our shortcomings in understanding the pathogenesis of Chagas disease, which, unfortunately, continues to figure among the most serious health problems of the American continent.

Pseudopycnadena tendu sp. nov. is described from the balistid Pseudobalistes fuscus from the waters off New Caledonia. It differs from the only other member of the genus P. fischthali Saad-Fares et Maillard, 1986, in its broad cirrus-sac, with the wide field of large gland-cells, its less nearly circular body shape, its dorsal excretory pore, its shorter post-testicular region, its relatively larger ventral sucker and its smaller eggs. The genus is re-defined to take these distinctions into account. Other opecoelid species reported from New Caledonia are Allopodocotyle epinepheli (Yamaguti, 1942) from Epinephelus cyanopodus, E. fasciatus and E. merra, Cainocreadium epinepheli (Yamaguti, 1934) from E. coeruleopunctatus, E. fasciatus and Variola louti, Hamacreadium mutabile (Linton, 1910) from Lutjanus fulviflamma and L. kasmira, Helicometra epinepheli Yamaguti, 1934 from E. fasciatus and E. merra, Orthodena tropica Durio et Manter, 1968 from Lethrinus lentjan, Pacificreadium serrani (Nagaty et Abdel-Aal, 1962) from Plectropomus leopardus and Pseudoplagioporus interruptus Durio et Manter, 1968 from Lethrinus rubrioperculatus. Abstract Pseudopycnadena tendu sp. nov. est décrit du baliste Pseudobalistes fuscus pêché en Nouvelle-Calédonie. L’espèce diffère du seul autre membre du genre, P. fischthali Saad-Fares et Maillard, 1986, par son sac du cirre plus épais avec un champ large de cellules glandulaires, sa forme du corps presque circulaire, son pore excréteur dorsal, sa partie post-testiculaire plus courte, sa ventouse ventrale relativement plus grande et ses œufs plus petits. Le genre est redéfini pour prendre en compte ces distinctions. D’autres Opecoelidae sont mentionnés de Nouvelle-Calédonie: Allopodocotyle epinepheli (Yamaguti, 1942) de Epinephelus cyanopodus, E. fasciatus et E. merra, Cainocreadium epinepheli (Yamaguti, 1934) de E. coeruleopunctatus, E. fasciatus et Variola louti, Hamacreadium mutabile (Linton, 1910) de Lutjanus fulviflamma et L. kasmira, Helicometra epinepheli Yamaguti, 1934 de E. fasciatus et E. merra, Orthodena tropica Durio et Manter, 1968 de Lethrinus lentjan, Pacificreadium serrani (Nagaty et Abdel-Aal, 1962) de Plectropomus leopardus et Pseudoplagioporus interruptus Durio et Manter, 1968 de Lethrinus rubrioperculatus.

Specimens of the fishes Siganus spinus L. (Siganidae) and Sargocentron spiniferum Forsskål (Holocentridae) were caught in the Red Sea off the coast of Sharm El-Sheikh, South Sinai, Egypt. Twenty-three (46%) and 12 (20%) of these fishes, respectively, were found to harbour intestinal trematodes. Siganus spinus was parasitized by Helicometra marmoratae Nagaty et Abdel-Aal, 1962 (Opecoelidae Ozaki, 1925) and S. spiniferum by Helicometra aegyptense sp. nov. (Opecoelidae Ozaki, 1925). Based on a large number of specimens collected from its type host and locality, H. marmoratae is broadly redescribed for the first time, and its type specimen is re-examined. The validity of this species is discussed and considered a new synonym of H. fasciata (Rudolphi, 1819) Odhner, 1902 (type species of the genus). Helicometra aegyptense sp. nov. is similar to H. equilata (Manter, 1933) Siddiqi et Cable, 1960, H. nasae Nagaty et Abdel-Aal, 1962, H. pteroisi (Gupta, 1956) Fischthal et Kuntz, 1965 and H. interrupta Hassanine, 2005 in having a short forebody and a long cirrus sac extending posterior to the ventral sucker, but differs significantly from them or unique in having a distinctly elongate pharynx, a larger sucker ratio and vitelline follicles grouped in small clusters arranged in two lateral rows on each side of the body. The valid species of Helicometra are listed in four principal groups.

During a re-assessment of tapeworm collections from wild birds in Slovakia, two Anomotaenia spp. were recovered from the intestine of the little ringed plover Charadrius dubius Scop., 1786. One of them is described as Anomotaenia barusi sp. nov. The new taxon is distinguished from related congeneric species by the different shape and size of the rostellar hooks, the number of testes and the morphology of male and female reproductive organs. The other species was identified as Anomotaenia alata Spassky et Konovalov, 1969. The validity of this species has formerly been questioned because of its striking morphological similarity to the type-species of the genus, A. microrhyncha (Krabbe, 1869), described from the same host, Philomachus pugnax (L.). Present data revealed differences in the number and measurements of the rostellar hooks, the size of the cirrus-sac, the armament of the cirrus and the presence or absence of setae at the polar ends of the inner egg envelope, which supported the validity of A. alata. The finding of A. alata in C. dubius from Slovakia represents a new host and geographical record.

Post-embryonic development and fully-formed polycephalic larvae of Taenia parva Baer, 1926 were examined by light (LM) and transmission electron microscopy (TEM). Three developmental stages were recognised: (1) an early stage of exogenous budding at the surface of the central vesicle; (2) a stage of polycephalic cyst development accompanied by segmentation of the growing larval strobile and an obvious decrease in the size of the central vesicle; (3) fully-formed larval strobile and invaginated scoleces. In fully-developed encysted polycephalic larvae, there are usually 14–24 segmented larval strobilae, each terminating with an invaginated scolex; larval strobilae arise from a common central vesicle and remain attached posterior to it during the entire development. The number of segments varies between 109 and 120 per larval strobila. The polycephalic larvae examined closely resemble the strobilocercus type of taeniid larvae. The structure of developing and fully-formed larvae was examined by TEM. The tegument, scolex, subtegumental musculature of the strobilar segments, protonephridial system, calcareous corpuscles and medullary parenchyma of larvae exhibit general similarity with the same structures in adults at both LM and TEM levels. The morphogenesis of the larva of T. parva is compared with that of the polycephalic larvae of other Taenia spp. (T. krepkogorski, T. twitchelli and T. endothoracica) and with other asexually-multiplying cestode larvae (mesocestoidids, hymenolepidids and dilepidids).

The nematode Rhabdochona cotti Gustafson, 1949 is redescribed from specimens collected from the intestine of the blue ridge sculpin Cottus caeruleomentum (a new host record), a recently described fish species, from Little Fishing Creek in Maryland, USA. The measurements of these specimens, collected in November 2005, are generally smaller than those reported in the original description of R. cotti, this being probably associated with the nematode’s seasonal maturation cycle or the different host species. As revealed by SEM, the deirids of R. cotti are simple (not bifurcate), in which this species differs from almost all North American congeners. Of these, simple deirids, filamented eggs and a rounded tail tip in females occur only in Rhabdochona longleyi, but it distinctly differs from R. cotti in the smaller number of anterior prostomal teeth (6 vs. 14). Rhabdochona rotundicaudatum is considered a junior synonym of Rhabdochona cascadilla; numerous specimens of the latter were collected from Semotilus atromaculatus, Luxilus cornutus and Notropis rubellus from the type locality (Eramosa River, Ontario, Canada) (unpublished). Rhabdochona paxmani and Rhabdochona salmonis are synonymized with Rhabdochona kisutchi, whereas Rhabdochona californiensis is considered a junior synonym of R. cascadilla. The need of a taxonomic revision of North American species of Rhabdochona is stressed.

Oxyascaris mcdiarmidi sp. nov. (Nematoda, Cosmocercidae) from the small intestine of Duellmanohyla uranochroa from Costa Rica is described. Oxyascaris mcdiarmidi sp. nov. represents the 4th species assigned to the genus and is distinguished from congeners by the distribution pattern of the caudal papillae of the male, spicule length and vulvar position.

Syringoplutarchusia, a new genus of the syringicolous feather mite family Syringobiidae (Pterolichoidea), is described based on a single new species, S. nordmanni sp. nov., collected from the feather quills of a museum specimen of the Black-winged Pratincole Glareola nordmanni Fischer, 1842 (Glareolidae). Absence of adanal discs and complete reduction of setae d and e on tarsi IV in males of the new genus is unique in this family. The highly elongated body shape of both sexes is most similar to the genera Plutarchusia Oudemans, 1904 and Paidoplutarchusia Dabert, 2003 but strong sclerotization of coxal fields and hypertrophied posterior legs with variously shaped apophyses resemble more advanced syringobiid mites, e.g. Syringobia Trouessart et Neumann, 1888. Syringoplutarchusia represents the first syringobiid from this host family. The taxonomic status of the new taxon is discussed.

The objective of this study was to investigate the incidence and density of Demodex folliculorum in the patients with rheumatoid arthritis (RA). Forty-one patients with RA and twenty-seven age and sex matched healthy controls were enrolled in this study. Disease Activity Score (DAS 28) was used for the assessment of disease activity. Out of 41 patients, 33 were females and 8 males. The mean disease duration was 10.9 ± 8.2 years. The mean DAS 28 was 3.8 ± 1.2. No statistically significant differences in the incidence and density of Demodex mites were found between patients with RA and controls. Although immunosuppression is thought to be a risk factor for the D. folliculorum infestation no such correlations could be found in the 41 immunosuppressed patients with RA, therefore, further studies with larger groups are needed.

Eighteen strains of Trypanosoma cruzi isolated from two species of triatomines in the state of Paraná, Brazil, were characterized molecularly using three strategies: RAPD (randomly amplified polymorphic DNA) with four primers, analysis of the D7 polymorphic region of the 24Sα rDNA, and RFLP (restriction fragment length polymorphism) of region 5′ of the mitochondrial gene COII (cytochrome oxidase subunit 2). The phenogram constructed with the RAPD data showed that only three strains isolated from Panstrongylus megistus collected in the Municipality of Arapongas were grouped together in a sub-branch. None of the other 15 strains could be clustered according to triatomine species or geographical origin. The strains were grouped with the T. cruzi I reference sample, indicating closer association with the sylvatic transmission cycle of T. cruzi in the state of Paraná. However, analyses of the rDNA and COII gene polymorphisms revealed the presence of populations from both T. cruzi I and II major lineages. In half of the analyzed triatomines, we found parasites from both lineages coinfecting the same bugs. Of these, most (6/9) were isolated from Triatoma sordida, and 3/9 from Panstrongylus megistus. These results contribute to a better comprehension of the ecoepidemiology of Chagas’ disease in Paraná, and raise questions about the role of studies of polyclonal population dynamics for controlling the transmission of T. cruzi to humans in this region.

Lice of mammals spend the entire life cycle in the host hair, thus, the microclimate found near the mammal skin is likely to influence the structure of louse communities. Here we use a comparative approach to examine the effect of mammals’ diving behavior on the taxonomic richness of their lice. We compared the mean genera richness of lice, and — as potential confounding variables — the mean species richness of host, and the mean body mass of host between diving clades and their non-diving sister clades. Louse genera richness was significantly lower in clades of aquatic mammals than on their non-diving sister clades. Host species richness was not significantly different between these clades. Body mass was significantly higher in clades of aquatic mammals, however, the direction of this difference cannot explain the difference in parasite taxonomic richness. This study suggests that mammals’ diving behavior can effectively shape their ectoparasite communities.