Parasites of wild sea bass Dicentrarchus labrax from Norway. (25/611)

Thirteen wild sea bass from the Oslo fjord in south-eastern Norway were examined for parasites. Nineteen species were found, comprising 5 protozoans, 1 monogenean, 8 digeneans, 1 cestode, 2 nematodes and 2 crustaceans. Based on the similarity to the parasitic fauna of Mediterranean sea bass, it is predicted that sea bass farmers in Northern Europe will experience the same parasite problems as sea bass farmers in warmer regions.  (+info)

The evolution of parasites from their hosts: intra- and interspecific parasitism and Emery's rule. (26/611)

In some taxa of Hymenoptera, fungi, red algae and mistletoe, parasites and their hosts are either sibling species or at least closely related (Emery's rule). Three evolutionary mechanisms have been proposed for this phenomenon: (i) intraspecific parasitism is followed by sympatric speciation; (ii) allopatric speciation is followed by secondary sympatry and the subsequent parasitism of one sibling species by the other; and (iii) allopatric speciation of a species with intraspecific parasitism is followed by secondary sympatry, in which one species becomes an obligate parasite of the other. Mechanisms (i) and (ii) are problematic, while mechanism (iii) has not, to our knowledge, been analysed quantitatively. In this paper, we develop a model for single- and two-species evolutionary stable strategies (ESSs) to examine the basis for Emery's rule and to determine whether mechanism (iii) is consistent with ESS reasoning. In secondary sympatry after allopatric speciation, the system's evolution depends on the relative abundances of the two sibling species and on the proportional damage wrought by parasites of each species on non-parasitic members of the other. Depending on these interspecific effects, either the rarer or the commoner species may become the parasite and the levels of within-species parasitism need not determine which evolves to obligate parasitism.  (+info)

Preadult stage parasites and multiple timed exposure to infective larvae are involved in development of limb edema in Brugia malayi-infected Indian leaf monkeys (Presbytis entellus). (27/611)

The pathogenesis of filarial limb edema is not known. The role of parasitological variables and parasite-mediated phenomena in the development of limb edema was investigated in the Presbytis entellus-Brugia malayi model. Infection was initiated with subcutaneous inoculation of infective third-stage larvae (L(3)), and the animals were reexposed to different doses of L(3) at the prepatent, patent, and diminishing microfilaremia (0 to 5% of peak microfilaremia count) stages of infection. A large L(3) inoculum size and repeated inoculation in the ankle region during the prepatent, patent, and diminishing microfilaremia stages of infection were found to be necessary for reproducible induction of limb edema. The preadult stage of the parasite was found to be the most potent inducer of limb edema, followed by L(5) and L(4). The presence of the proinflammatory cytokines tumor necrosis factor alpha, interleukin-1beta, and interleukin-6 in edema fluid in the leg receiving the parasite challenge indicated that the limb edema development was due to parasite-mediated cytokine responses. The absence of bacterial infection or anti-streptolysin O titer in the edema fluid and blood indicated that bacterial infection is not necessary for the development of limb edema.  (+info)

Vampires, Pasteur and reactive oxygen species. Is the switch from aerobic to anaerobic metabolism a preventive antioxidant defence in blood-feeding parasites? (28/611)

Several species of parasites show a reduction of their respiratory activity along their developmental cycles after they start to feed on vertebrate blood, relying on anaerobic degradation of carbohydrates to achieve their energy requirements. Usually, these parasites choose not to breathe despite of living in an environment of high oxygen availability such as vertebrate blood. Absence of the 'Pasteur effect' in most of these parasites has been well documented. Interestingly, together with the switch from aerobic to anaerobic metabolism in these parasites, there is clear evidence pointing to an increase in their antioxidant defences. As the respiratory chain in mitochondria is a major site of production of reactive oxygen species (ROS), we propose here that the arrest of respiration constitutes an adaptation to avoid the toxic effects of ROS. This situation would be especially critical for blood-feeding parasites because ROS produced in mitochondria would interact with pro-oxidant products of blood digestion, such as haem and/or iron, and increase the oxidative damage to the parasite's cells.  (+info)

Seasonal prevalence of intestinal parasites in the United States during 2000. (29/611)

One-third of 5,792 fecal specimens from 2,896 patients in 48 states and the District of Columbia tested positive for intestinal parasites during the year 2000. Multiple infections with 2-4 parasitic species constituted 10% of 916 infected cases. Blastocystis hominis infected 662 patients (23% or 72% of the 916 cases). Its prevalence appears to be increasing in recent years. Eighteen other species of intestinal parasites were identified. Cryptosporidium parvum and Entamoeba histolytica/E. dispar ranked second and third in prevalence, respectively. Prevalence of infection was lowest (22-27%) in winter, gradually increased during the spring, reached peaks of 36-43% between July and October, and gradually decreased to 32% in December. A new superior method of parasite detection using the Proto-fix-CONSED system for fixing, transport, and processing of fecal specimens is described. In single infections, pathogenic protozoa caused asymptomatic subclinical infections in 0-31 % of the cases and non-pathogenic protozoa unexpectedly caused symptoms in 73-100% of the cases. The relationship between Charcot-Leyden crystals and infection with four species of intestinal parasites is examined and the list of provoking parasitic causes is expanded.  (+info)

Sequence-based genomics. (30/611)

A report on the Genome-Based Pathogen Biology meeting, Hinxton, UK, 7-10 July 2002.  (+info)

Status of intestinal parasites infection among primary school children in Kampongcham, Cambodia. (31/611)

A survey was made to find the extent of intestinal parasite infection in Kampongcham, Cambodia in February 2002. A total of 251 fecal specimens were collected from Tonlebat primary school children and examined by formalin-ether sedimentation technique. The overall infection rate of intestinal parasite was 54.2% (males, 57.3%; females, 50.8%). The infection rate of intestinal helminths by the species were as follows: Ascaris lumbricoides 26.3%, Echinostoma sp. 15.6%, hookworm 6.4%, Opisthorchis sp. 4.0%, Rhabditis sp. 2.4%, and Trichuris trichiura 0.4%. The infection rate of intestinal protozoa were as follows: E. coli 7.6%, G. lamblia 3.2%, I. butschlii 3.2%, and E. histolytica 0.8%. More than two different kinds of parasites were found in 16.7% of the stool samples. All the children infected were treated with albendazole, praziquantel and metronidazole according to parasite species. The results showed that intestinal parasites are highly endemic in this area.  (+info)

The effect of some ecological factors on the intestinal parasite loads of the Asian elephant (Elephas maximus) in southern India. (32/611)

Some ecological factors that might potentially influence intestinal parasite loads in the Asian elephant (Elephas maximus Linn.) were investigated in the Nilgiris, southern India. Fresh dung samples from identified animals were analysed, and the number of eggs/g of dung used as an index of parasite load. Comparisons across seasons and habitats revealed that parasite loads were significantly higher during the dry season than the wet season, but were not different between the dry-deciduous and dry-thorn forests in either season. After accounting for the effect of age on body condition, there was no correlation between body condition, assessed visually using morphological criteria, and parasite load in either season. Individuals of different elephant herds were not characterized by distinct parasite communities in either season. When intra-individual variation was examined, samples collected from the same individual within a day differed significantly in egg densities, while the temporal variation over several weeks or months (within a season) was much less. Egg densities within dung piles were uniform, enabling a simpler collection method henceforth.  (+info)