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PubMed1975

Effect of diethylcarbamazine on third stage Brugia malayi larvae in cats.

Forty-one experimental and 37 control cats were each infected with 50 Brugia malayi larvae in such a way that a preponderance of the larvae remained localized in the popliteal lymph node or in the lymphatics of the leg draining into that node. During the 1st week after infection cats were treated with varying doses of diethylcarbamazine citrate (DEC). Two weeks after infection, necropsy for worm recovery was performed on treated and control cats. No living larva was recovered from 21 of 22 cats treated with a total of 10 mg DEC/kg body weight or greater. A single living larva was recovered in only 2 of 5 cats treated at 5 mg/kg. At 2 mg/kg, 8 of 10 cats had substantially fewer larvae than their controls; the remaining 2 were negative. In 4 cats treated with a total of 1 mg/kg, there was no reduction of larvae. All 37 untreated controls harbored living larvae, with a mean of 56% of the inoculum being recovered.

Brugia↗

PubMed1975

Studies on filariasis. IV. The rate of escape of the third-stage larvae of Brugia pahangi from the mouthpart of Aedes togoi during the blood meal.

The rate of escape of the third-stage larvae of Brugia pahangi from Aedes togoi which were allowed to probe on a cat and a mouse at time intervals of 5, 10, 20, 30 and 60 seconds was studied. The rate of escape of third-stage larvae at all time intervals was greater during probing on the cat than on the mouse, and was in a logarithmic linear relation to the length of probing time by the mosquito host. The greatest loss (91.35%) of third-stage larvae was in mosquitoes which fed on a cat until fully gorged. There was a remarkable rate of escape (57.41%) within 5 seconds. This striking rate of escape of third-stage larvae may have important implications on filariasis transmission. Most larvae migrated towards the proboscis and head of mosquitoes during these feeding periods. Nearly equal numbers of third-stage larvae escaped from mosquitoes which fed to repletion for more than 60 seconds on a mouse and from those which probed fro more than 60 seconds on the same mouse but did not engorge. This confirmed our view that filling up of the stomach with blood does not constitute the single factor in causing the release of third-stage larvae from the mosquito host.

Aedes↗

PubMed1978

Observations on the infectivity of parasitic third-stage larvae of Uncinaria lucasi Stiles 1901 (Nematoda: Ancylostomatidae) of Northern fur seals, Callorhinus ursinus Linn., on St. Paul Island, Alaska.

Twelve fur seal pups, which had not nursed their mothers, were used in an infectivity experiment. Pups were exposed to parasitic 3rd-stage larvae of Uncinaria lucasi from belly tissues of fur seal bulls, bachelors, and pregnant cows, to determine maturation capability of the larvae. Hookworms were not recovered from the intestines of 3 pups receiving larvae from belly blubber of bulls, 6 pups receiving larvae from belly blubber of bachelors, and 1 nonexposed pup. Maturation of hookworms did occur in 2 pups exposed to larvae from a mixture of belly blubber, mammary tissue, and milk of pregnant cows. Parasitic 3rd-stage hookworm larvae from belly tissues of pregnant and "non-pregnant" fur seal cows averaged 938.1 and 802.1 micron long, and 34.1 and 31.5 micron wide, respectively; however, larvae from belly tissues of a fur seal bull, bachelors, 2-year-old males, male and female yearlings and pups, and Steller Sea Lion subadults averaged 640.5-732.0 micron long and 20.9-24.9 micron wide.

Abdominal Muscles↗

PubMed1975

[Method of selection of synchronously developing larvae of Drosophila melanogaster].

Methods of obtaining synchronously developing larvae were comparatively evaluated. Larvae were selected by distinct morphological features: time of hatching, second larval moult, pupation. Both virgin and non-virgin females were taken in the experiment. The degree of synchronism was estimated by the interval during which pupation took place in all larvae of the sample. When selecting larvae at the time of second moult, the pupation of all selected larvae was completed within 8 hrs. All other methods of obtaining synchronously developing larvae give a spread of pupation from 12 to 25 hrs. A simple modification of the method of larval selection during the second moult is proposed which allows to obtain a large amount of synchronously developing larvae of the 3rd instar.

Animals↗

PubMed1976

The bionomics of the free-living larvae and the transmission of Dictyocaulus filaria between lambs in North-East England.

The bionomics of the free-living larvae of Dictyocaulus filaria on pasture, and the transmission of infection between lambs, were studied during different seasons of the year in North-East England. The rate of development of first-stage larvae to the third stage took 4-9 days in late spring and summer, 1 1/2-4 weeks in autumn and 5 1/2-7 weeks in winter. The proportion of first-stage larvae developing to the third stage ranged from 10-28% in autumn and winter, and 2-25% in spring and summer. The rate of mortality of the third-stage larvae was approximately logarithmic in nature, although the survival time was shorter in spring and summer than in autumn and winter. Third stage larvae were able to survive from autumn until the spring of the following year in sufficient numbers to perpetuate transmission but not to cause clinical disease. In a transmission study, the survival of the infective larvae on the experimental plot was poor in summer, but the larval population increased in the autumn and then declined slowly throughout the winter. Infection in the susceptible lambs was related to the level of infection on the herbage increasing in severity from early summer to late autumn. However, those lambs infected in the summer were resistant to the heavy autumn challenge of larvae on pasture.

Animals↗

PubMed2026

Comparative genomics and phenotypic divergence of ERIC I and ERIC II genotypes of Paenibacillus larvae, the causative agent of American Foulbrood disease.

Honeybees of the species Apis mellifera are important pollinators of crops and wild plants. Paenibacillus larvae, a spore-forming bacterium, is a problematic pathogen that causes American foulbrood (AFB) in honeybee larvae worldwide. In many countries, AFB is a notifiable disease, requiring the destruction of diseased colonies, resulting in economic loss that impacts beekeeping and agriculture. Disease onset starts with larval ingestion of P. larvae spores, which germinate into growing cells that proliferate in the larval gut, leading to larval death and eventually bee colony collapse. As infection progresses, P. larvae produce spores, reinitiating the disease cycle. Thus, growth, sporulation and germination underlie AFB. In this study, using various microbiological assays, quantitative cell biology methods, transmission electron microscopy and genomics, we sought to identify genetic and phenotypic characteristics associated with the predominant ERIC I and ERIC II genotypes of P. larvae during growth, sporulation and germination. Extending previous findings, our data identify genetic differences between ERIC I and ERIC II strains and some genetic variation between strains of the same ERIC type. Furthermore, we describe significant differences in cellular morphology during growth, differences in spore envelope structure and differences in germination efficiency between ERIC I and ERIC II genotypes. Collectively, our findings improve understanding of P. larvae biology and provide a foundation for developing genotype-specific disease management strategies for AFB.

Animals↗

PubMed1979

Sensitivity differences displayed by Drosophila melanogaster larvae of different ages to the toxic effects of growth on media containing aflatoxin B1.

Using Drosophila melanogaster, the relative sensitivities of various larval stages to the toxic effects of growth on media supplemented with either 0.44 or 0.88 ppm aflatoxin B1 (AFB1) were determined. Two strains of fruit flies were tested: strain A-11 which is relatively resistant to AFB1 induced toxicity, and strain A-9 which is quite sensitive. Eggs, mid-first, mid-second and early-, mid- and late-third instar larvae were transferred onto AFB1 media and allowed to complete larval and pupal development and eclose as adults. At the 0.44 ppm concentration, strain A-11 showed no effect, while only first instar larvae of strain A-9 showed significant mortality rates for first instar larvae, but the A-9 larvae die at higher rates than the A-11 larvae. In addition, second and third instar larvae of strain A-9 show significant mortality rates when grown at 0.88 ppm AFB1, while these stages are not affected in strain A-11.

Aflatoxins↗

PubMed1976

Differential egg cannibalism among larvae of Tribolium castaneum as influenced by the antennapedia mutation.

Egg cannibalism by antennapedia and wide-type larvae of Tribolium castaneum was analyzed for two age groups (14 and 15 days old) with egg densities of 100 and 400. The effects of larval density and egg genotype (+ or ap) were also analyzed. The + larva consumed more eggs than ap larvae at both ages for the egg densities tested. Both strains were more cannibalistic at 14 days, consumed a higher percentage of eggs when egg density was increased among 14-day larvae, and tended to consume slightly more eggs of the opposite genotype when they were provided independently. However, neither strain discriminated between eggs of differing genotype when both were provided simultaneously. Egg cannibalism of the + strain increased when both genotypes of eggs were available. Reciprocal F1 hybrid larvae were similar in cannibalistic ability to the strain which served as a male parent. Larvae from "F2 recovered" ap beetles cannibalized fewer eggs than either original strain or the heterozygotes, further implicating the possible pleiotropic effect of the ap mutation on egg cannibalism.

Animals↗

PubMed1978

Larvae of Anisakidae in marine fish of coastal waters near Jakarta, Indonesia.

Three species of marine fish were collected from the waters around Seribu Islands, near Jakarta, Indonesia, and examined for nematode larvae of the family Anisakidae. Larvae were found in 719 (49%) of 1.459 Rastrelliger kanagurta, 445 (50%) of 884 Decapterus russelli, and 217 (41%) of 531 Sardinella sirm. Larvae from a subsample of 150 infected fish, 44 R. kanagurta, 86 D. russelli, and 20 S. sirm, were examined microscopically and only Anisakis type I and Terranova type B larvae were found. In all three species of fish the Anisakis larvae predominated. The Anisakis larvae found in these fish are a potential source of infection for humans in Indonesia; however, human anisakiasis has not yet been reported from this country.

Animals↗

PubMed1992

[A method for acquiring newborn larvae of Trichinella spiralis in vitro].

This paper reports a simple method for acquiring numerous newborn larvae of Trichinella spiralis in vitro. Adults of T. spiralis, collected from small intestine on rats which were infected with infective larvae separated from mice infected experimentally, were put into tissue culture bottle containing M199. Then the bottles were incubated in CO2 incubator (37 degrees C, 5% CO2) for 15-20h. The newborn larvae were collected by passing through filtration, centrifugation and repeated wash. The results showed that this method is effective in terms of the activity of the adults and newborn larvae and the amount of larvae gained. The method in economical and can control bacterial contamination to a certain extent and extract ES antigen of adults and newborn larvae from the culture solution.

Animals↗

PubMed1977

On the escape of infective filarial larvae from the mosquitoes.

Experimentally infected females of Culex pipiens fatigans carrying infective larvae of Wuchereria bancrofti were fed, on the 16th day p.i., on four different solutions, which were offered "cold" (24 degrees C) or "warm" (34 degrees C) in Petri dishes as open fluids. Thus the sucking mosquitoes did not have to bend their labia. Only the "warm" human serum stimulated any considerable number of infective larvae (24.8%) to leave the mouthparts of the mosquitoes. 1289 infective C. fatigens females lost only an estimated 6.4% of their infective larvae of W. bancrofti, when they were maintained on sugar-water until their natural death. Most of the more heavily infected mosquitoes died relatively soon after the filarial larvae had reached maturity (15-20 days p.i.). The main stimulus provoking the filarial larvae to migrate into the labium is believed to be the movement of the muscles of the pharyngeal pump. Mature larvae protrude their anterior ends from the tip of the labellum. There they seem able to distinguish between suitable and unsuitable external conditions and accordingly they will either leave the proboscis completely or retract into the labium.

Animals↗

PubMed1977

A comparison of individual dissection and mass separation for recovery of Onchocerca larvae from vector black flies.

The effectiveness of a mass separation technique, previously used for the extraction of larvae of lymphatic-dwelling filarial worms from batches of vector mosquitoes, was tested as a means of recovering infective-stage larvae of Onchocerca volvulus from Simulium ochraceum in Guatemala. Blood-engorged flies, collected from 10 infected human attractants, were maintained for 9 days to allow ingested microfilariae to develop to the infective stage. The numbers of Onchocerca larvae recovered after groups of these flies were crushed and washed into tissue culture fluid in Baermann funnels was compared with the numbers obtained by individual dissections of flies fed on the same subjects. The mass separation procedure gave a mean recovery rate of 0.03 larva/fly and detected larvae only in flies which had fed on those subjects with the highest microfilarial skin densities. Dissections yielded 0.50 larva/fly (a 16.7-fold increase) and detected larvae in flies collected from all test subjects. The explanation for the ineffectiveness of the mass separation technique may lie in the observed sluggishness of infective-stage Onchocerca larvae and a consequent inability to free themselves from the fly fragments in the Baermann funnel.

Animals↗

PubMed1978

[Study of the spiral and spindle-shaped formations in cultures of Bacillus larvae (White 1906) causing foulbrood in bees].

The authors have been studying the bacterial diseases of the brood for a fairly long time. American and European foul brood has been studied with the highest attention. Cultures of Bacillus larvae (White, 1906) were examined both in freshly isolated strains and in collection strains of this micro-organism. In cases of foul brood, the pathological material was found to contain not only the typical rods of B. larvae but also immobile spiral forms which are usually referred to in literature as fragments or developmental forms of B. larvae. These spiral forms were found to constitute spindle-shaped formations in the culture of B. larvae; the multiplication of these spindles depends on the presence of the rods of B. larvae and their development and reproduction can be observed on wet gelatine agar in a Petri dish turned upside down under a normal microscope (10 X 10 magnification). In the combined liquid medium, used in the experiments, these formations disintegrate into immobile spirals; if re-cultivated on a solid medium they re-assume their spindle shape with transverse meridian arrangement (in different amounts). Staining for proving the presence of nucleic acids does not eliminate the possibility of these formations being separate micro-organisms which cannot be stained by current staining methods but can be represented by the contrast method according to Burri, or by silvering according to Klein. The authors succeeded to separate these micro-organisms, but without the rods of B. larvae the colonies of these formations are feeble.

Animals↗

PubMed1977

Variations in macromolecular antifreeze levels in larvae of the darkling beetle, Meracantha contracta.

Overwintering larvae of the darkling beetle, Meracantha contracta, produce a macromolecular antifreeze that is similar in activity to the glycoproteinaceous and proteinaceous antifreezes found in some cold-water, marine teleost fishes. The antifreeze is not present in the hemolymph of the Meracantha larvae in summer, but its production begins by late September in the wild population. The antifreeze reaches a maximum concentration in February, decreases slowly through spring, and disappears by early June. The supercooling points of the larvae are lowest in February, when the antifreeze levels are highest, and increase as the antifreeze concentrations in the hemolymph decrease in the spring. Larvae collected in mid-February and warm-acclimated lost the antifreeze with-in 12 days. Larvae collected in early September and cold-acclimated required nearly two months to produce concentrations of antifreeze comparable to those of overwintering larvae. Temperature seems to be the major environmental factor responsible for the control of antifreeze levels in Meracantha; however, other environmental factors may also be involved.

Animals↗

PubMed1977

Development and survival of Haemonchus contortus larvae on pastures in Ibadan.

The development and survival of the eggs of Haemonchus contortus on pasture at Ibadan were studied by spreading faeces containing eggs on grass plots from October 1973 to October 1974. Development of the eggs to the infective larvae took place within one week in May, June, July, September and October. Larvae were not recovered in the other months. Their survival times were 28, 42, 42, 35, 63 and 49 days respectively in October 1973. May, June, July, September and October 1974. Rainfall was the most important epizootiological factor which influenced the development and survival of the infective larvae. Development of the eggs to the infective larvae took place when the mean daily rainfall for the first 7 days was 3 mm or more. The survival time of the larvae appeared to be prolonged when rain fell evenly throughout the periods the larvae were on pasture.

Animals↗

PubMed1979

The epidemiology of equine strongylosis in southern Queensland. 2. The survival and migration of infective larvae on herbage.

The seasonal changes in longevity on herbage of the infective larvae of strongylid nematodes of the horse were studied. During the summer months, 1% of the larvae survived on herbage for 2-3 weeks, with 0.2% still viable for a further 2-3 weeks. Equivalent survival periods in winter were 7-11 weeks and over 11 weeks respectively. During spring and autumn, larvae survived for periods varying from 3-8 weeks. On Rhodes grass (Chloris gayana) growing vigorously in the summer of 1976, the majority of larvae remained in the lowest layers of the pasture, within 10 cm of the soil surface. Very few reached the highest fraction of grass sampled, above 40 cm from the soil. More larvae were recovered higher on the pasture in a period when less torrential rain had occurred. It was concluded that the parasitological benefits to be gained from short-term mixed grazing with horses and cattle may be minimal, in view of the tendency of cattle to eat only the upper layers of the pasture initially, with a consequent increase in the number of infective larvae per unit weight of herbage remaining.

Animals↗

PubMed1976

Nutritional evaluation of wheat and barley cultivars by growth rate and body composition of larvae of Tenebrio molitor.

Larvae of the yellow mealworm, Tenebrio molitor L., Gembloux strain, race F, were reared on diets of 17 cultivars of wheat and 29 cultivars of barley, prepared for determination of digestible energy with mice, for 4 weeks at 27 +/- 0.25 degrees C and 65 +/- 5% relative humidity. Values for percentage crude protein of tissues of larvae fed wheat cultivars were significantly and positively correlated with values for digestible energy as determined with mice. These values were not correlated for larvae fed barley cultivars; however, values for per cent dry matter content of larvae were significantly and positively correlated with values for digestible energy determined with mice. This apparent discrepancy is explained on the basis of the chemical constitution of barley and the availability of amino acids of barley to the larvae. Use of larvae of Tenebrio molitor to indicate the digestible energy of cereal grains is feasible, provided that the proper parameter is chosen. Nevertheless, use of this biological method seems more suitable for evaluation of protein quality and of amino acid availability than for a measure of digestible energy of feeds.

Animal Nutritional Physiological Phenomena↗

PubMed1976

Transplacental migration of Toxocara canis larvae in experimentally infected mice.

In experimentally infected, nonpregnant mice the larvae of Toxocara canis were not found in the uterus at any time. In mice infected at 1 week, but not at 2 weeks, before gestation, larvae were found in the uterus but not in either the placenta or fetus. In mice infected during pregnancy, larvae were found in the uterus and placenta from the 9th day and in the fetus from the 11th day of pregnancy, more abundantly when infected at the middle than at the earlier stages. Examination of microsections revealed larvae in both maternal sinusoidal spaces and fetal blood vessels of the placenta; though mechanical damage to the tissues and the debris of tissues were sometimes seen, larva-associated inflammation in these tissues were not observed. The results suggest that in the pregnant mouse the migration of T. canis larvae is influenced by the developmental stages of the placenta.

Animals↗