Studies on Trypanosoma vivax: comparison of parasitological diagnostic methods.

Leeflang P., Buys Janny and Blotkamp Coby. 1978. Studies on Trypanosoma vivax: comparison of parasitological diagnostic methods. International Journal for Parasitology8: 15–18. Parasitological methods for the diagnosis of Trypanosoma vivax infections in Nigerian cattle, including thin and thick blood smear and lymph gland smear examination, haematocrit centrifuge technique, hypotonie lysis test and mouse inoculation were evaluated. In 155 blood samples, thick film examination was significantly better than thin smear examination; in 126 samples, the haematocrit centrifuge technique was significantly superior over thin smear but not over thick film examination; when all six methods were applied in 52 samples, significant differences could only be demonstrated between mouse inoculation on one hand and thick film and gland smear examination, haematocrit centrifuge technique and hypotonie lysis test on the other hand, and between thin smear examination and hypotonic lysis test. It was shown that none of the tests was either satisfactory or sufficiently reliable to be used alone. The combination of either haematocrit centrifuge technique or thick film examination together with thin smear examination is recommended as most practical for the diagnosis of T. vivax infection under field conditions. The haematocrit centrifuge technique is also more advantageous because simultaneous estimation of the packed cell volume will evaluate the clinical condition of the herd. A comparison of the value of diagnostic methods for East and West African T. vivax was included in the present study.     

Host-parasite relationships in gamasid mites of the genus Hirstionyssus (Acari:Parasitiformes:Gamasina) in the south of the West Siberian Plain

The paper reports data on host-parasite relationships in gamasid mites of the genus Hirstionyssus Fonseca and small mammals in the south of the West Siberian Plain.     

Evidence for the presence of Ctenocephalides orientis in livestock dwellings in northwest Iran

Fleas are important vectors of diseases such as murine typhus, tularaemia, hymenolepiasis and plague. The presence of active foci and history of human‐ and flea‐transmitted plague in northwest Iran prompted the present group to collect and identify fleas from human and livestock dwellings across West Azerbaijan Province. Adult fleas were collected and identified using routine taxonomic keys. Species designation was confirmed by sequencing the cytochrome oxidase subunit I (COI). Of the collected specimens (n = 989), 104 were collected off‐host (30 from human dwellings and 74 in light traps) and the rest were found on hosts (107 on animals and 778 by human bait). Of these fleas, 394 (40%) were male and 595 (60%) were female. The collected specimens belonged to the species Ctenocephalides canis, Ctenocephalides felis, Ctenocephalides orientis and Pulex irritans (all: Siphonaptera: Pulicidae). The amplified COI fragment, in addition to confirming the morphological identification of species, showed good efficacy in separating the different species in the phylogenetic analysis. In addition to the identification of fleas from human and livestock dwellings using morphological and molecular characteristics, the current paper represents the first report of the presence of C. orientis in northwest Iran. This finding suggests that changing climate conditions may have expanded the distribution of this species.     

The electric organ discharges of the Petrocephalus species (Teleostei: Mormyridae) of the Upper Volta System

In this study, a first comparative investigation of all four species of Petrocephalus ( P. bovei , P. bane , P. soudanensis and P. cf. pallidomaculatus ) present in the Upper Volta system and their electric organ discharges (EOD) was conducted. It was found that P. bovei was the most widespread (in terms of habitat use), but in several places P. bovei , P. soudanensis and P. cf. pallidomaculatus occurred syntopically. All species emitted a triphasic signal, and with very few exceptions, the Petrocephalus species of the Upper Volta system could clearly be identified on the basis of their EOD waveforms. The most obvious differences between species in EOD waveforms were in amplitude of the last phase, total duration and fast Fourier transformation (FFT) peak frequency. No sexual dimorphism was present in the EOD of any species although external dimorphism, i.e. an indentation at the base of the anal fin of mature males, was common. The EOD waveform diversity in the Upper Volta principally resembled that found in four sympatric Petrocephalus species from the Ogooué system (Gabon) and might play a role in species recognition and speciation processes.     

A rural–urban latitudinal study of the distributions of Culex quinquefasciatus and Culex pipiens bioforms in their southernmost sympatric fringe

Mosquitoes grouped in the complex Culex pipiens L. (Diptera: Culicidae) are important vectors of medical and veterinary diseases. In the South American sympatric region, Cx. pipiens and Culex quinquefasciatus Say coexist and potentially hybridize. To identify key drivers of their geographical distribution, mosquito immatures were collected from flower vases of eight urban/rural cemetery pairs within a 5° latitudinal transect along Buenos Aires Province, Argentina. The specimens were identified by molecular methods and their relative proportion modelled as a function of environmental variables. At the beginning of the warm season, northern and southern cemeteries presented exclusively Cx. quinquefasciatus and Cx. pipiens, respectively, with different proportions of both at mid latitudes. By the end of the summer, Cx. quinquefasciatus was present throughout the study area, exclusively in 11 of the 16 cemeteries both rural and urban, whereas Cx. pipiens was predominant only in the southernmost pair. Mean annual temperature, photoperiod variability and time of the season were key drivers of their distributions. All specimens of Cx. pipiens were identified as form molestus and no hybrids were recognized. The reported distribution patterns and the potential absence of Cx. pipiens f. pipiens and hybrids are discussed, along with their implications in disease transmission.     

Is there a future for elephants in West Africa?

The elephants of West Africa have experienced a long history of human disturbance. Before 1800 they were much affected by the precolonial empires of the savanna and Sahelian zones, the trans-Saharan trade routes, and the coastal trade established by the Europeans. During the 19th century, the increasing demand for ivory from Europe and North America, the European penetration of the region, and the evolution of breech-loading rifles devastated the remaining elephants. The elephant population of West Africa collapsed before the outbreak of World War I because of intense hunting for ivory. This collapse pre-empted the decline that would have occurred anyway due to the rapid growth of the human population and consequent loss of habitat. Elephants now find themselves in about 70 small isolated populations that cover only 5% of the region. These fragments are very vulnerable – whether in the arid lands or the humid forests – to poaching and general human disturbance. There are few data on numbers; most of the population estimates are guesses. Two-thirds of the populations are thought to consist of fewer than 200 animals and therefore have a low probability of surviving the next century. As more habitat is lost to human activities, West African elephants will soon remain only in protected areas. But many parks and reserves are managed poorly and cannot offer effective protection; they do not guarantee a future for elephants. In addition, their crop-raiding habit makes elephants unpopular in rural communities surrounding protected areas. Human populations are expected to continue growing and resources for conservation are scarce. The future of West African elephants lies in a small network of well-protected areas.     

Changes in suppressor, helper, and B-cell functions in aging mice

Suppressor, T-helper, and B-cell functions were measured in spleen cells derived from individual mice of varying ages. Suppressor activity was assessed by the ability of test cells to suppress the secondary anti-hapten response of young-adult spleen cells in mixed cultures. T-Helper-cell activity was assessed by measuring the ability of T cells activated with carrier-anti-carrier immune complexes to restore the response of hapten-primed, T-depleted syngeneic cells. B-Cell activity was assessed by measuring the response to the T-independent antigen DNP-Ficoll. It was found that the suppressor function increased rapidly, reached a peak in middle-aged mice, and remained elevated thereafter. In contrast, T-helper and B-cell functions declined at a constant rate from young adulthood to old age. An exception to this pattern was found in a distinct subpopulation of aged mice, which had splenomegaly and extremely low suppressor, T-helper, and B-cell functions.     

Effects of estradiol and testosterone on the activity of pyruvate kinase of the cardiac and skeletal muscles of rats as a function of age and sex

The specific activities of pyruvate kinase of cardiac and skeletal (gastrocnemius) muscles of adult rats of both sexes are lower than those of immature rats. The activity does not change after adulthood in the cardiac muscle, but decreases in the gastrocnemius. The activity of pyruvate kinase of the heart of immature and adult rats of both sexes decreases after castration, but is unaffected in old rats. Castration has no effect on the activity of pyrovate kinase of the gastrocnemius muscle of rats of both sexes at any age. In invo administration of estradiol (50 μg/100 g body weight) increases the activity of pyruvate kinase of the heart of castrated male and female rats of the three ages. For the skeletal muscle, the activity increases in castrated adult female and old male rats only. A higher dose (100 μg) of estradiol has variable effects on pyruvate kinase of the heart of male and female castrated rats of different ages. This dose increase pyruvate kinase significantly in the skeletal muscle of old castrated male and female rats. However, it decreases it in the skeletal muscle of adult castrated male rats. Testosterone (100 μm) increases the activity of pyruvate kinase of the heart of castrated male rats. This increase is lower in old age. It has no effect in the heart of castrated female rats of any age. Testosterone (50 μg) increases pyruvate kinase activity of the skeletal muscle of young ovariectomized rats only. A higher dose (100 μg) causes a significant increase in pyruvate kinase of the skeletal muscle of castrated adult and old male, and young and adult female rats, respectively. These data show that sex steroid hormones induce pyruvate kinase of striated muscles, and that the age- and sex-dependent variations may be due to changes in the levels of receptor proteins.     

Effect of CdS preparation on the photo-catalyzed decomposition of hydrogen sulfide in alkaline aqueous media

Band-gap irradiation of CdS dispersions in alkaline aqueous media (pH 14) containing 0.1 M Na₂S produces hydrogen and sulfur. The reaction is photo-decomposition of hydrogen sulfide by two quanta of visible light (λ > 400 nm). Various batches of commercially available cadmium sulfide, as well as CdS precipitated from nitrate, sulfate, and chloride solutions at neutral pH, produce different amounts of hydrogen. Electronically pure CdS (puratronic grade) generates almost no hydrogen. By contrast, CdS precipitates prepared in the presence of excess cadmium yield forty times more hydrogen than CdS prepared in the presence of excess sodium sulfide. Differences are rationalized in terms of possible surface modification and/or changes in the active sites by anions present as ‘impurities’ which could affect separation and recombination of the charge carries, e_CB⁻ and h_VB⁺, in CdS.