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PubMedDate not supplied

Parasitic Protozoa of the blood of rodents. V. Plasmodium vinckei brucechwatti subsp. nov. A malaria parasite of the thicket rat, Thamnomys rutilans, in Nigeria.

A description is given of the blood stages of a new subspecies of Plasmodium vinckei in the blood of naturally infected thicket rats (Thamnomys rutilans) from Nigeria and experimentally infected mice. Sporogony was obtained at 25 degrees C in Anopheles stephensi A. quadrimaculatus and A.l. atroparvus, but sporozoites in the salivary glands of the mosquitoes were never infective. The new parasite is differentiated from 7 other species of malaria parasites of African rodents principally on the morphology of the erythrocytic stages. It is designated as a subspecies of P. vinckei (P.v. brucechwatti subsp. nov.) because of the (i) zoogeography, (ii) morphology of sporogonic stages and (iii) forms isoenzymes of blood stages.

Animals↗
PubMed2004

[Diagnosis and treatment of CNS parasite infection with special reference to parasitic myelitis].

The occurrence of visceral larva migrans due to Ascaris suum (A. suum) and Toxocara canis (T. canis) has occasionally been reported in Japan, although parenchymatous involvement of the CNS is extremely rare in A. suum/T. canis visceral larvae migrans. Recently we experienced 7 cases with myelitis caused by visceral larva migrans due to A. suum/T. canis (parasite myelitis). The characteristics of this myelitis are: (1) sensory disturbances (Lhermitte's sign, paresthesia, and hypesthesia) are predominant symptoms, while severe motor weakness is rare, (2) spinal cord lesions on T2-weighted MRI show more extensive lesions compared with mild symptoms, (3) Gadolinium enhancement of spinal cord lesions are limited as compared with spinal cord lesions on T2-weighted MRI lesions, (4) Some cases show the presence of eosinophils in CSF, while others show Th2 deviation in CSF supernatant, and (5) Tests for anti-A. suum/T. canis IgG antibody are strongly positive in serum and CSF. Moreover, 6 percent of 108 consecutive cases with non-compression myelopathy presenting at the Department of Neurology at Kyushu University Hospital from January, 1998 to December, 2002 had parasitic myelitis. Myelitis from visceral larva migrans due to A. suum/T. canis might be overlooked because of its mild neurologic impairment without systemic symptoms, but should be considered as one of the differential diagnoses in non-compression myelopathy.

Adult↗
PubMed1986

Parasites of domestic and wild animals in South Africa. XXI. Arthropod parasites of vaal ribbok, bontebok and scrub hares in the western Cape Province.

Vaal ribbok (Pelea capreolus), bontebok (Damaliscus dorcas dorcas) and scrub hares (Lepus saxatilis) were slaughtered in the Bontebok National Park at regular intervals and examined for arthropod parasites. Twelve species of ixodid ticks were recovered; the antelope each harboured 9 species and the hares 11. Rhipicephalus nitens was the most prevalent and most abundant tick. The vaal ribbok also harboured large numbers of Ixodes pilosus and the bontebok fairly large numbers of Rhipicephalus glabroscutatum. The vaal ribbok were infested with 2 lice species and the larvae of 3 oestrid fly species. The bontebok harboured 2 lice species and the larvae of 2 oestrid flies, and the scrub hares were infested with a louse species and a flea species. The host preference and seasonal abundance of some of the parasites were determined.

Animals↗
PubMed1978

[Parasites of Salmo trutta L. from the Titino River. Part III. Histological observations of parasites of the intestinal tract].

During researches on helminth parasites of Salmo trutta L. from the River Tirino (L'Aquila - Italy) histological studies of the intestinal tract of brown trout infected by the following species: Crowcrocaecum testiobliquum (Wisnewski, 1932) Skrjabin e Koval, 1956; Cyathocephalus truncatus (Pallas, 1781);o Truttaedacnitis truttae (Fabricius, 1794) Petter, 1974 and Dentitruncus truttae Sinzar, 1955 have been carried out. The attachment of the single species and the histological changes in the host gut due to parasite species have been described.

Animals↗
PubMed1983

Restricted sets of parasite antigens from the surface of different stages and sexes of the nematode parasite Nippostrongylus brasiliensis.

Surface molecules of parasitic stages of the nematode Nippostrongylus brasiliensis can be readily iodinated by the chloramine T technique, and assessed for antigenic reactivity with humoral antibody from infected animals. Free-living infective larvae are less amenable to analysis by this, or similar methods, but within 18 hr of larvae entering the host, new macromolecular surface antigens can be detected. The parasites change their surface antigens twice more in the course of the maturation to the adult stage. Surface antigens are stage-specific: lung larvae (L3), intestinal larvae (L4) and gut-living adults each possess characteristic sets of cuticular molecules. Single stage infections result in antibody reactive only to the antigens from the homologous stage. The adult surface appears to bear the greatest number of antigens, one of which is found only on the male worm. The composition of these antigens does not differ grossly between adult worms from a naive or immune host, or worms established after the adaptation of a 'trickle' (multiple low dose) infection. There appears to be an interesting contrast between the rapidity and extent of changes in surface antigens in the early phases of infection, and the stability of adult antigens analysed at different points in the host immune response.

Animals↗
PubMed1997

Intestinal parasites among food-handlers in Qualyobia Governorate, with reference to the pathogenic parasite blastocystis hominis.

A total of 1700 male food handlers, above 20 years of age who came for health clearance certificate were the subjects of the present study. Health assessment questionnaire was filled out on each person including dietary habits, water supply, history of diarrhoeal disease. Clinical examination and stool samples collection in 3 alternative days were performed. The food handlers were divided into symptomatic (700) and saymptomatic (1000). Different concentration methods as well as test tube culture for Strongyloides larvae were done. Samples were preserved in PVA, trichrome stained slides were examined for protozoal parasites. Nineteen percent had intestinal parasites, G. lamblia, E. histolytica, A.. lumbricoides, S. mansoni, A. duodenale, T. trichura, H. nana, St. stercoralis, E. vermicularis and mixed infection & non-pathogenic; E. coli, I. Butschlii, C. mesnilli, E. nana, T. hominis and mixed infection. Blastocystis hominis was recovered from stools of 8.5% of symptomatic and 4% of asymptomatic. 2.4% symptomatic and 2% asymptomatic had B. hominis significant infection. B hominis was considered significant if > 5 organisms per HPF was counted. Significant infection was higher among symptomatic than asymptomatic persons with detectable faecal leucocytes especially eosinophils. The authors recommended that physicians as well as diagnostic parasitologists should be aware of the potential clinical significance of B. hominis especially, when present alone in significant number, otherwise positive cases must be considered as carriers and followed up for any ill effects.

Adult↗
PubMed2005

Parasite histories and novel phylogenetic tools: alternative approaches to inferring parasite evolution from molecular markers.

Parasitological research is often contingent on the knowledge of the phylogeny/genealogy of the studied group. Although molecular phylogenetics has proved to be a powerful tool in such investigations, its application in the traditional fashion, based on a tree inference from the primary nucleotide sequences may, in many cases, be insufficient or even improper. These limitations are due to a number of factors, such as a scarcity/ambiguity of phylogenetic information in the sequences, an intricacy of gene relationships at low phylogenetic levels, or a lack of criteria when deciding among several competing coevolutionary scenarios. With respect to the importance of a precise and reliable phylogenetic background in many biological studies, attempts are being made to extend molecular phylogenetics with a variety of new data sources and methodologies. In this review, selected approaches potentially applicable to parasitological research are presented and their advantages as well as drawbacks are discussed. These issues include the usage of idiosyncratic markers (unique features with presumably low probability of homoplasy), such as insertion of mobile elements, gene rearrangements and secondary structure features; the problem of ancestral polymorphism and reticulate relationships at low phylogenetic levels; and the utility of a molecular clock to facilitate discrimination among alternative scenarios in host-parasite coevolution.

Animals↗
PubMed1986

Bioecology of the parasites of high altitude homeothermic host-parasite systems. II. Infections by strobilocerci of Hydatigera balaniceps (Hall), H. laticollis (Rudolphi) and H. parva (Baer) in relation to sex, size and weight of Indian house rat.

The influence of sex, size and weight of the Indian house rat (Rattus rattus) on concurrent liver infections with Hydatigera balaniceps (Hall), H. laticollis (Rudolphi) and H. parva (Baer) has been discussed. A significant inverse relationship was recorded between cestode infection and rat size. Parasitization index and mean worm burden-host weight ratio decreased with increase in rodent weight.

Altitude↗
PubMed2000

Parasites and parasite stages of free-ranging wild lions (Panthera leo) of northern Tanzania.

Fecal samples from 33 lions (Panthera leo) in Serengeti National Park and Ngorongoro Crater Conservation Area in northern Tanzania contained 19 different parasites, 12 of which, including Aelurostrongylus sp., a species of Acanthocephala, a species of Anoplocephalidae, Capillaria sp., Demodex sp., Eimeria sp., Habronema sp., Isospora felis, Isospora rivolta, one species of Isospora that was previously undescribed from lions, one species of Trematoda that was previously undescribed from lions, and Trichuris sp., were new reports for lions. Seven other species had been previously reported from lions.

Animals↗
PubMed1986

Phosphorylcholine bearing components of some helminthic parasites: localization to parasite lipoproteins.

Extracts of various helminthic parasites were studied to determine the molecular carrier of the hapten phosphorylcholine (Pc). Physicochemical studies showed that the carrier was heterogeneous with regard to apparent molecular weight (70,000-greater than 10(6) daltons). Ultracentrifugal analysis of Ascaris suum and Nippostrongylus brasiliensis showed that Pc was associated with low (LDL), high (HDL) and a heterogeneous group of very high density (VHDL) lipoproteins. The majority of Pc was found in the most dense VHDL (d greater than 1.25 g ml-1). The apparent molecular weight and particle diameter of A. suum HDL was 751,000 daltons and 16.2 nm, respectively. The apparent molecular weights and particle diameters of A. suum VHDL ranged from 469,000 to 677,000 daltons and 13.6 to 15.5 nm, respectively. The electrophoretic mobilities of A. suum LDL and HDL were beta and gamma, respectively. A suum VHDL was electrophoretically heterogeneous. It is probable that Pc is associated with the phospholipid phosphatidylcholine.

Animals↗
PubMed2003

Speciation and host-parasite relationships in the parasite genus Gyrodactylus (Monogenea, Platyhelminthes) infecting gobies of the genus Pomatoschistus (Gobiidae, Teleostei).

Using species-level phylogenies, the speciation mode of Gyrodactylus species infecting a single host genus was evaluated. Eighteen Gyrodactylus species were collected from gobies of the genus Pomatoschistus and sympatric fish species across the distribution range of the hosts. The V4 region of the ssrRNA and the internal transcribed spacers encompassing the 5.8S rRNA gene were sequenced; by including published sequences a total of 30 species representing all subgenera were used in the data analyses. The molecular phylogeny did not support the morphological groupings into subgenera as based on the excretory system, suggesting that the genus needs systematic revisions. Paraphyly of the total Gyrodactylus fauna of the gobies indicates that at least two independent colonisation events were involved, giving rise to two separate groups, belonging to the subgenus Mesonephrotus and Paranephrotus, respectively. The most recent association probably originated from a host switching event from Gyrodactylus arcuatus, which parasitises three-spined stickleback, onto Pomatoschistus gobies. These species are highly host-specific and form a monophyletic group, two possible "signatures" of co-speciation. Host specificity was lower in the second group. The colonising capacity of these species is illustrated by a host jump from gobiids to another fish order (Anguilliformes), supporting the hypothesis of a European origin of Gyrodactylus anguillae and its intercontinental introduction by the eel trade. Thus, allopatric speciation seems to be the dominant mode of speciation in this host-parasite system, with a possible case of sympatric speciation.

Animals↗
PubMed2001

Limitation of Trypanosoma brucei parasitaemia results from density-dependent parasite differentiation and parasite killing by the host immune response.

In the bloodstream of its mammalian host, the "slender" form of Trypanosoma brucei replicates extracellularly, producing a parasitaemia. At high density, the level of parasitaemia is limited at a sublethal level by differentiation to the non-replicative "stumpy" form and by the host immune response. Here, we derive continuous time equations to model the time-course, cell types and level of trypanosome parasitaemia, and compare the best fits with experimental data. The best fits that were obtained favour a model in which both density-dependent trypanosome differentiation and host immune response have a role in limiting the increase of parasites, much poorer fits being obtained when differentiation and immune response are considered independently of one another. Best fits also favour a model in which the slender-to-stumpy differentiation progresses in a manner that is essentially independent of the cell cycle. Finally, these models also make the prediction that the density-dependent trypanosome differentiation mechanism can give rise to oscillations in parasitaemia level. These oscillations are independent of the immune system and are not due to antigenic variation.

Animals↗
PubMed2000

Helminth parasites of the western painted turtle, Chrysemys picta belli (Gray), including Neopolystoma elizabethae n. sp. (Monogenea: Polystomatidae), a parasite of the conjunctival sac.

Neopolystoma elizabethae n. sp. is described from the conjunctival sac of the western painted turtle Chrysemys picta belli (Gray), from the Upper Peninsula of Michigan. This is the first species found in this location from chelonians in North America. The new species differs from all other species of Neopolystoma in possessing a circle of 8 genital spines that are recurved and possess a crescent-shaped base. Eight additional species of helminths were found in the 5 turtles examined in this study. All are common parasites of North American freshwater turtles. An additional species of Monogenea (Polystomoidespauli) was found in the oral cavity. Four species of Digenea (Eustomos chelydrae, Allassostomoides chelydrae, Spirorchis kirki, and Spirorchis parvus) and 3 species of Nematoda (Spiroxys contorta, Serpinema trispinosus, and Amphibiocapillaria serpentina) were also found. The following are reported from Michigan for the first time: P. pauli, S. kirki, and A. serpentina.

Animals↗
PubMed2003

Recrudescence in artesunate-treated patients with falciparum malaria is dependent on parasite burden not on parasite factors.

Artemisinin derivatives are first-line antimalarial drugs in Thailand. No firm evidence of clinically relevant artemisinin resistance exists. When used as monotherapy, artesunate has been associated with a high treatment failure (recrudescence) rate, which could be due to low-level artemisinin resistance. To understand the causes of recrudescence, we retrospectively studied a cohort of 104 malaria patients treated with artesunate monotherapy, 32 of whom recrudesced. There was no difference in in vitro artesunate sensitivities between 6 nonrecrudescent isolates and 16 paired admission and recrudescent isolates. Paired admission and recrudescent isolates from 10 patients were genotyped; only 3 had pfmdr1 mutations. Patients with admission parasitemias >10,000 per microl had a 9-fold higher likelihood of recrudescence (adjusted odds ratio) compared with patients with lower parasitemias. This study suggests (1) recrudescence after treatment with artesunate is not the result of inherent parasite resistance, and (2) admission parasitemia may be useful in choosing therapeutic options.

ATP-Binding Cassette Transporters↗
PubMed2003

Parasites of domestic and wild animals in South Africa. XLI. Arthropod parasites of impalas, Aepyceros melampus, in the Kruger National Park.

Ectoparasites were collected from impalas, Aepyceros melampus, at four localities within the Kruger National Park, namely Skukuza, in the Biyamiti region, Crocodile Bridge and Pafuri. Animals were also examined at Skukuza during a severe drought and at Skukuza and Pafuri towards the end of a second drought. Parasite burdens were analysed in relation to locality, sex, age class, month and drought. The impalas were infested with 13 ixodid ticks species, including two that were identified only to genus level. Except for four animals at Pafuri, all were infested with Amblyomma hebraeum. The highest intensity of infestation with larvae of this tick occurred from April to June and during November and December at Skukuza and in the Biyamiti region. Infestation with nymphs was highest during late winter. All animals were infested with Boophilus decoloratus, and the intensity of infestation was highest during spring. The intensity of infestation with Rhipicephalus appendiculatus was highest at Crocodile Bridge and at Pafuri, and that of Rhipicephalus zambeziensis at Skukuza. With both the latter species the intensity of infestation of larvae was highest from April to August, of nymphs from July to September or October and of adults during February and March. Rhipicephalus kochi was present only at Pafuri. The impalas also harboured five louse species and two species of hippoboscid flies. The intensity of infestation with lice tended to be greater during late winter and spring than during other seasons and greater on lambs than on yearlings on which it was greater than on adult animals.

Animals↗
PubMed2004

Fine-structural details of the photoreceptor membranes in the ocellus of the scale-insect parasite Centrodora sp. (Hymenoptera; Aphenelidae): a case of gene transfer between host and parasite?

Only one insect (the scale insect Eriococcus sp.) is known, in which photoreceptive lamellae appear to have replaced the usual arthropod rhabdom microvilli. We are now reporting the presence of photoreceptive membranes, which also appear to resemble lamellae rather than microvilli, but they are in the ocellus of the tiny wasp Centrodora sp., which parasitizes scale insect eggs. The apparently optically homogenous lens of the Centrodora ocellus measures approximately 10 microm in diameter and, thus, operates at the limits of diffraction. We calculated that the lens is capable of focusing a parallel bundle of rays on the retina of the ocellus.

Animals↗
PubMed1983

Parasites of domestic and wild animals in South Africa. XVI. Helminth and arthropod parasites of blue and black wildebeest (Connochaetes taurinus and Connochaetes gnou).

Fifty-five blue wildebeest ( Connochaetes taurinus ) were shot for parasite recovery at approximately monthly intervals during a period of 13 months in the Kruger National Park. Thirteen nematode species, 4 cestode species, 1 trematode, the larvae of 5 oestrid flies, 3 lice species, 7 ixodid tick species, 1 mite species and the nymphae of a pentastomid were recovered. The seasonal prevalence of 8 nematodes, 2 cestodes, the larvae of 4 oestrid flies, 2 lice and 4 ixodid tick species was determined. The endo- and ectoparasite burdens of 7 black wildebeest ( Connochaetes gnou ) shot in the Golden Gate Highlands Park in the Orange Free State and 3 shot in the Rietvlei Reserve in the Transvaal were determined. These animals harboured 4 nematode species, 1 cestode, the larvae of 5 oestrid fly species, 2 lice species, 4 ixodid tick species and a mite species.

Animals↗