Molecular identification of the causative agent of human strongyloidiasis acquired in Tanzania: dispersal and diversity of Strongyloides spp. and their hosts.

In order to identify the causative agent of imported strongyloidiasis found in a Japanese mammalogist, who participated in a field survey in Tanzania, the hyper-variable region IV (HVR-IV) of 18S ribosomal DNA and partial mitochondrial cytochrome c-oxidase subunit 1 gene (cox1) were analyzed and compared with Strongyloides fuelleborni collected from apes and monkeys of Africa and Japan, and S. stercoralis from humans, apes and dogs. The HVR-IV and cox1 of the patient's worms were identical to or only slightly differed from those of worms parasitic in Tanzanian chimpanzees and yellow baboons, demonstrating that the patient acquired the infection during her field survey in Tanzania. Phylogenetic analysis with the maximum-likelihood method largely divided isolates of S. fuelleborni into three groups, which corresponded to geographical localities but not to host species. Meanwhile, isolates of S. stercoralis were grouped by the phylogenetic analysis into dog-parasitic and primate-parasitic clades, and not to geographical regions. It is surmised that subspeciation has occurred in S. fuelleborni during the dispersal of primates in Africa and Asia, while worldwide dispersal of S. stercoralis seems to have occurred more recently by migration and the activities of modern humans.

Hyper-variable regions in 18S rDNA of Strongyloides spp. as markers for species-specific diagnosis.

Four hyper-variable regions (HVR-I to -IV) found in 18S ribosomal DNA sequences were compared among 34 isolates of 15 species of the genus Strongyloides to evaluate their diagnostic value. HVR-I to -III were short, and plural species exhibit the same nucleotide arrangement. Meanwhile, HVR-IV had 23 to 39 nucleotides, showing species-specific arrangements, except Strongyloides ransomi and Strongyloides venezuelensis, which had the same nucleotide sequence in HVR-IV but were readily distinguished by the difference in HVR-I and -III. Isolates of Strongyloides stercoralis from humans of USA, Japan, and Philippines, chimpanzees, and dogs had an identical sequence in this region. Meanwhile, intraspecific polymorphism in HVR-IV nucleotide arrangement was observed among isolates of Strongyloides fuelleborni and Strongyloides callosciureus, presumably reflecting process of geographical dispersal and adaptation to the hosts.

Helminths collected from imported pet murids, with special reference to concomitant infection of the golden hamsters with three pinworm species of the genus Syphacia (Nematoda: oxyuridae).

A total of 210 individuals of 13 species belonging to 4 subfamilies of Muridae imported into Japan as pets were examined; 5 species of Syphacia (Nematoda: Oxyuridae), Aspiculuris tetraptera (Nematoda: Heteroxynematidae), and Rodentolepis nana (Cestoidea: Hymenolepididae) were collected. Concurrent infection with 3 pinworm species, Syphacia mesocriceti, Syphacia stroma, and Syphacia peromysci, was recorded for the first time in the golden hamster, Mesocricetus auratus. Syphacia mesocriceti was also identified in the desert hamster, Phodopus roborovskii, and S. peromysci was recovered from the fat-tailed gerbil, Pachyuromys duprasi, and the Cairo spiny mouse, Acomys cahirinus. From the pygmy mouse, Mus minutoides, an undetermined species closely resembling Syphacia megaloon and Syphacia ohtaorum, both parasitic in Mus spp., was collected. Females of another undetermined Syphacia sp. were observed in the greater Egyptian gerbil, Gerbillus pyramidum. All of the host-Syphacia associations, except S. mesocriceti in the golden hamsters, were recorded for the first time. It is suggested that overlapping breeding situations provided the opportunity for host switching by the pinworms.

Paracosmocercella rosettae n. gen. et n. sp. (Nematoda: Cosmocercoidea: Cosmocercidae) collected from the Japanese tree frog, Hyla japonica (Anura: Hylidae), in Japan.

A new genus, Paracosmocercella (Nematoda: Cosmocercoidea: Cosmocercidae), is proposed with monotypic Paracosmocercella rosettae n. sp. from the Japanese tree frog, Hyla japonica Günther, 1859, in Oita, Kyushu Island, Japan. Paracosmocercella resembles Cosmocercella and Cosmocercoides by having 2 rows of rosette papillae without plectanes ventrally in preanal region of male, but it is readily distinguished from Cosmocercella by lacking clear vesicle supporting rosette papillae and from Cosmocercoides by lacking rosette papillae in perianal region and having large-sized eggs, which hatch in uterus.

Mitochondrial cytochrome c oxidase subunit 1 gene and nuclear rDNA regions of Enterobius vermicularis parasitic in captive chimpanzees with special reference to its relationship with pinworms in humans.

Sequences of mitochondrial cytochrome c oxidase subunit 1 (CO1) gene, nuclear internal transcribed spacer 2 (ITS2) region of ribosomal DNA (rDNA), and 5S rDNA of Enterobius vermicularis from captive chimpanzees in five zoos/institutions in Japan were analyzed and compared with those of pinworm eggs from humans in Japan. Three major types of variants appearing in both CO1 and ITS2 sequences, but showing no apparent connection, were observed among materials collected from the chimpanzees. Each one of them was also observed in pinworms in humans. Sequences of 5S rDNA were identical in the materials from chimpanzees and humans. Phylogenetic analysis of CO1 gene revealed three clusters with high bootstrap value, suggesting considerable divergence, presumably correlated with human evolution, has occurred in the human pinworms. The synonymy of E. gregorii with E. vermicularis is supported by the molecular evidence.

Effects of repeated anthelmintic treatment on Enterobius vermicularis infection in chimpanzees.

Effects of repeated treatment with pyrantel pamoate on Enterobius vermicularis infection in chimpanzees were assessed by observing worms discharged in the feces after administration of anthelmintic treatment. Three of 9 chimpanzees reared in a zoological garden in Japan were subjected to fecal worm count and morphometric observation, and all were given oral pyrantel pamoate 6 times at 10-day intervals simultaneously. Following the first and second treatments, more than 30,000 pinworms were discharged from 1 chimpanzee. The number of discharged worms abruptly decreased after the third treatment, and only a few worms were recovered after the fifth treatment, indicating that repeated treatment at short intervals was very effective. Complete eradication was not achieved, however, presumably because of reinfection. The female proportion among discharged worms tended to increase as the treatment was repeated.

Morphology of chimpanzee pinworms, Enterobius (Enterobius) anthropopitheci (Gedoelst, 1916) (Nematoda: Oxyuridae), collected from chimpanzees, Pan troglodytes, on Rubondo Island, Tanzania.

The chimpanzee pinworm, Enterobius (Enterobius) anthropopitheci (Gedoelst, 1916) (Nematoda: Oxyuridae), is redescribed based on light and scanning electron microscopy of both sexes collected from the feces of chimpanzees, Pan troglodytes, of an introduced population on Rubondo Island, Tanzania. Enterobius (E.) anthropopitheci is characterized by having a small body (males 1.13-1.83 mm long, females 3.33-4.73 mm long), a rather straight spicule with a ventral membranous formation in males, double-crested lateral alae in females, small eggs (53-58 by 24-28 microm), and a smooth eggshell with 3 longitudinal thickenings. Morphological comparison is made between the present and previous descriptions.

Redescription of Pterygodermatites (Mesopectines) nycticebi (Mönnig, 1920) (Nematoda: Rictulariidae), a parasite of slow loris Nycticebus coucang (Mammalia: Primates).

Pterygodermaties (Mesopectines) nycticebi (Mönnig, 1920) (Nematoda: Spirurida: Rictulariidae) is redescribed based on immature and mature adults collected from the stomach and small intestine at autopsy of a slow loris, Nycticebus coucang (Boddaert, 1785) (Mammalia: Primates), in a zoological garden in Japan. It is first demonstrated that male possesses a minute telamon and a left lateral pore in the preanal part of body. The cause of death of the slow loris is strongly surmised to be related to the nematode infection, which was apparently acquired under captivity in the zoological garden.

Growth of Enterobius vermicularis in a chimpanzee after anthelmintic treatment.

The growth of Enterobius vermicularis in a chimpanzee was investigated by observing worms discharged in feces after administration of pyrantel pamoate. Just after the final molting, immature adult male pinworms developed to a fully mature stage in 2 wk, after passing through a stage corresponding to the so-called Enterobius gregorii, which was surmised to be a younger adult form of E. vermicularis. The frequency distribution of body length forms 2 peaks in both male and female pinworms, with a depression in the transitional forms from the immature to the fully mature stage. This depression seems to be the result of more rapid growth or lower susceptibility to the drug in this transitional stage. Pyrantel pamoate effectively eradicated mature males, but gravid females were continuously observed in the feces after treatment. The complete eradication of pinworm infection by pyrantel pamoate could be achieved by repeated treatment at intervals shorter than 2 wk. This treatment would eradicate male worms first, resulting in females producing only unfertilized eggs, from which only males might hatch.

Embryogenesis of the dipluran Lepidocampa weberi Oudemans (Hexapoda, Diplura, Campodeidae): External morphology.

The external features of the embryo of the dipluran, Lepidocampa weberi Oudemans are described. The long germ band is formed, and blastokinesis is a simple flexion of the germ band. The primary dorsal organ is formed between the cephalic and abdominal ends by concentration of serosal cells. The mouth fold is formed by ventral extension of the intercalary, mandibular, and maxillary terga, through which entognathy is completed. The posteroventral region of the mouth fold develops into the admentum. Rotation of the labial anlagen is involved in labial formation, and the glossa, paraglossa, and labial palp acquire a tandem arrangement. The postmentum is formed by fusion of the labial subcoxae and is appendicular in origin. The styli and exertile vesicles are derived from the distal parts of bifurcated appendicular anlagen of the second to seventh abdominal segments. The columnar appendage of the first abdominal segment is serially homologous with the exertile vesicles of the following segments. The abdomen is composed of ten segments, and the cercus is the appendage of the tenth, last abdominal segment. Embryogenesis of Lepidocampa weberi resembles that of the rhabduran Campodea staphylinus (Uzel, 1898) as well as that of the dicelluratan Japyx major (Silvestri, '33). It may be emphasized that the rhabduran and dicelluratan diplurans share important features such as entognathy formation and abdominal organization, and the resemblance between them seems to be close enough to postulate their close affinity. Some embryogenetic features, which Diplura and Collembola share, are recognized as plesiomorphic and the manner of entognathy formation may significantly differ. J. Morphol. 237:101-115, 1998. © 1998 Wiley-Liss, Inc.