Life cycle of Trichostrongylus retortaeformis in its natural host,the rabbit (Oryctolagus cuniculus)

The chronology of the life cycle of Trichostrongylus retortaeformis (Zeder, 1800) (Nematoda, Trichostrongyloidea) is studied in its natural host Oryctolagus cuniculus. The free living period lasted 5 days at 24 degrees C. Worm-free rabbits were each infected per os with T. retortaeformis larvae. Rabbits were killed at 12 h post-infection (p.i.) and every day from one day to 13 days p.i. By 12 h p.i., all the larvae were exsheathed and in the small intestine. The third moult occurred between 3 and 5 days p.i. and the last moult between 4 and 7 days p.i. The prepatent period lasted 12 to 13 days. The patent period lasted five and a half months. The four known life cycles of species of Trichostrongylus in ruminants were compared with that of T. retortaeformis. No significant difference was found except in the duration of the prepatent period. These similarities in the life cycles confirm the previously formulated hypotheses on the relationship between the parasites of the two host groups (Durette-Desset, 1985).     

The life history of Labiostrongylus eugenii, a nematode parasite of the Kangaroo Island Wallaby (Macropus eugenii): The parasitic stages

Smales L. R. 1977. The life history of Labiostrongylus eugenii, a nematode parasite of the Kangaroo Island Wallaby (Macropus eugenii): the parasitic stages. International Journal for Parasitology7: 457–461. Labiostrongylus eugenii infective larvae ingested by the Kangaroo Island Wallaby exsheathe on the saccular stomach wall, then invade the mucosa causing one or two chronic irritative hyperpastic nodules, each containing a number of larvae. Six to eight weeks later the larvae leave the stomach wall and moult to fourth-stage. The fourth-stage larva is characterized by eight lips, while the oesophagus and anterior intestine assume the adult form. The posterior ends of late fourth-stage larvae become sexually differentiated. Moulting to adult occurs after 6–8 weeks with the first gravid females being observed 3 months later. The prepatent period appears to last about 6 months. Reasons for failure of experimental infection trials and the epidemiological significance of the life cycle were discussed.     

Life history and pathogenesis of Gallegostrongylus australis (Nematoda: Angiostrongylidae) in muridae

Gallegostrongylus australis Spratt, Haycock & Walter, 2001 (Nematoda: Angiostrongylidae) developed in Deroceras panormitanum, Lehmannia nyctelia, L. flava and Milax gigates (Gastropoda). The first moult occurred at 18-19 days after infection (DAI) and the second moult at 28 DAI. Larvae were infective to experimental murid definitive hosts at 35 DAI. In experimentally infected Rattus fuscipes larvae moulted L3-4 at 3 DAI and L4-5 at 6-7 DAI. Patency in R.fuscipes, R. lutreolus, R. norvegicus and R. rattus occurred 27-64 DAI and duration varied from 7-392 days. Histopathological changes in the lungs of R. lutreolus and development of debilitating clinical signs, in contrast to R. fuscipes, suggests that the former host-parasite relationship may be the more recent one but other traits suggest the opposite. Patent infections were established in some wild R. rattus and some laboratory R. norvegicus but not in wild M. domesticus, laboratory M. musculus, rabbit, Oryctolagus cuniculus, and marsupial bandicoot, Isoodon macrourus.     

The Life Cycle of Eimeria bateri (Protozoa, Eimeriidae) in the Japanese Quail Coturnix coturnix japonicum

SYNOPSIS. Eimeria bateri, a parasite of the Indian quail, was described from laboratory infections in Japanese quail. First generation schizonts developed in the glands of the duodenum and upper intestine. Second, 3rd and 4th generation schizonts and gametocytes occurred in the villous epithelium. There was a gradual spread along the small intestine until the whole organ was affected. The prepatent period was 4 days and the patent period 6 days. Graded doses from 5,000 to 1,280,000 oocysts produced very little pathogenic effect in young quail. E. bateri did not infect young pheasants or chicks.     

Susceptibility of elk to lungworms from cattle

Two studies were conducted to determine the infectivity of the lungworm, (Dictyocaulus viviparus) of cattle origin, in Rocky Mountain elk (Cervus elaphus nelsoni) or wapiti. In the first study, each of three 9-mo-old elk was administered 3,000 D. viviparus larvae from cattle using a nasogastric tube. In the second study, four 16-mo-old elk were each inoculated with 2,000 D. viviparus from cattle using a nasogastric tube. Elk were observed daily for signs of respiratory disease, and fecal samples were collected during the studies and evaluated for lungworm larvae using a modified Baermann technique. One elk was euthanatized during the patent period for recovery of adult lungworms, and three elk were euthanatized after larvae were no longer detected in feces. Lungworm larvae were not detected before inoculation in any of the 16-mo-old elk, but were detected 22 days after inoculation in one elk, 23 days after inoculation in two elk and 24 days after inoculation in all four elk. The prepatent period of this cattle isolate of D. viviparus in elk is therefore 22 to 24 days. The precise prepatent period was not determined in the three 9-mo-old elk, but larvae were detected in all three elk 25 days after inoculation. Numbers of larvae ranged from 1/ to 101/g feces with peak larval detection occurring 32 to 50 days after inoculation. Elk shed larvae from 22 to 83 days after inoculation, and patent periods of the parasite ranged from 24 to 62 days. Clinical signs of respiratory disease, with the exception of mild coughing after exercise, were not observed during the infections. Results from this experiment indicated that D. viviparus larvae of cattle origin can mature in elk and larvae can be passed in large numbers in feces, but this cattle isolate of D. viviparus was not highly pathogenic in elk.     

The Life Cycle of Eimeria vermiformis Ernst,Chobotar and Hammond, 1971 in the Mouse Mus musculus1

SYNOPSIS. The life cycle of Eimeria vermiformis from the mouse Mus musculus is described from experimental infections. The prepatent period was 7 days, and the patent period 7–22+ days. Endogenous stages were in the lower 2/3 of the small intestine. Two generations of schizonts were found. Mature 1st generation schizonts, seen 4 days after inoculation, were 16–25 × 9–16 μ and had long vermiform merozoites. Mature 2nd generation schizonts were first seen 5 days after inoculation. They were 8–18 × 7–14 μ (mean 11.2 × 13.1 μ). Mature microgametocytes, 17–32 × 12–25 μ, were present 6 days after inoculation. Macrogametes with plastic granules were found at the same time. The life cycle of E. vermiformis is compared with those of other species of Eimeria from Mus.     

Instars ofMicroplitis rufiventris [Hym.: Braconidae] and their relative developmental speed under different photoperiods

The internal parasiteMicroplitis rufiventris Kok. passes through 3 instars but moults 3 times within its host. The last moult occuring just at emergence time. The morphology of the egg and larval stages of the parasite are discussed. At 27°C and a photoperiod of 6 h (6L:18D) the endo-developmental cycle of the parasite can summarize as follows: Egg 18–24 h; instar 1,4 days (fighting phase 48 h; feeding phase 30–48 h); instar 2, 12–18 h and instar 3,3 days. The effect of different photoperiods on the relative speeds of the endo-developmental stages of the parasite at each of 30, 25, 20°C were carefully studied. At the first 2 temperatures, the short photoperiod (6L:18D) accelerated the development of larval instars, while both of 18L:6D or 0L:24D slowed down the development. Under the latter photoperiods some larvae failed to moult and had emergence problems. The influence of photoperiod is significantly noticeable at 20°C. The incubation period of the egg-stage was prolonged significantly at 18L:6D and the development of larval instars was significantly faster and refined at 6L:18D. The factor(s) inhibiting the development of the egg-stage perhaps differ from those affecting the larval development. The ventral area of the host mid-gut among malpighian tubes seems to be where the surplus parasite larvae are eliminated by physical attack. A physiologically suppressed parasite larva is able to attack its developed competitor of the same age. Teratocytes cells perhaps play a part in eliminating the surplus parasite larvae by physiological suppression.     

Observations on the biology of Rhabdochona kidderi texensis, a parasite of North American cichlids

An examination of a sample of benthic invertebrates collected from the Upper San Marcos River in southwestern Texas, USA in September 1999 revealed that the nymph of the ephemeropteran Tricorythodes curvatus served as natural intermediate host of the nematode Rhabdochona kidderi texensis (Nematoda: Rhabdochonidae), an intestinal parasite mainly of the Rio Grande perch (Cichlasoma cyanoguttatum) in this locality; the prevalence of the parasite's third- and fourth-stage larvae in mayflies was 6.8% with the intensity of 1-2 larvae per nymph. Live R. kidderi texensis eggs collected from nematodes recovered from C. cyanoguttatum in Texas were transported to the Czech Republic, where they were used to experimentally infect nymphs of the palaearctic mayfly species Paraleptophlebia submarginata; the development of infective third- and fourth-stage larvae in this experimental intermediate host was completed after approximately 10 days at 19 degrees C. Infected nymphs were fed to aquarium-reared fishes, four Cichlasoma nigrofasciatum and one Oreochromis niloticus, of which only three of the former became infected. The last (fourth) moult of a male nematode was observed in C. nigrofasciatum 23 days p.i. and adult males and gravid females with not fully mature (non-embryonated) eggs in uteri on days 40 and 51 p.i. The prepatent period of R. kidderi texensis is approximately two months.     

Aspects of the life history of Muspicea borreli (Nematoda: Muspiceidae), parasite of the house mouse (Mus domesticus) in Australia

Prevalence of Muspicea borreli (Nematoda) infection in wild populations of Mus domesticus in forests in southeastern New South Wales and in rural Canberra, Australia was variable, relatively low and the parasite occurred predominantly in male mice. Experimental infection of BALB/c mice occurred only via subcutaneous inoculation but was achieved using i) adults containing embryonating eggs, ii) adults containing active larvae and iii) active larvae dissected from the uterus of female worms. Experimental infection was not established using adults containing unembryonated eggs and was not established via intraperitoneal, percutaneous nor oral routes. Evidence indicates that larvae develop to the infective stage in the uterus of the adult worm, suggests that an obligate developmental phase on the host skin does not occur and that autoinfection is possible. Experimental infection predominated in males; females rarely became infected. When male BALB/c mice were inoculated subcutaneously with M. borrelia, immediately paired with an uninoculated female and permitted to breed for 90 days, infection was found in male and female offspring only of the second and subsequent litters or in the breeding female partner. Transmission to the young occurred within 21 days of birth and fifth-stage M. borrelia were found in offspring of the second and subsequent litters only after 35 or more days. However, when a male was inoculated but mating delayed for 23 days, infection was found in progeny of the first and second litters. The life cycle is direct and the prepatent period in BALB/c mice is estimated at 50-60 days. The precise mode of transmission of the parasite in breeding pairs of mice was not determined but larvae remained active for approximately an hour in balanced saline solutions (pH = 7.2) and in human saliva but died under conditions emulating free-living (tap water pH = 7.1) and stomach (pepsin solution pH = 2) environments. Transmission was not effected by transplacental, transmammary nor transseminal routes. Consequently, it is difficult not to conclude that transmission may occur via penetration of skin or mucous membranes, and allogrooming behaviour may be particularly important in this regard.     

Bradyzoite-Induced Murine Toxoplasmosis: Stage Conversion, Pathogenesis, and Tissue Cyst Formation in Mice Fed Bradvzoites of - Different Strains of Toxoplasma gondii

ABSTRACT. The development of Toxoplasma gondii was studied in mice fed bradyzoites. At one hour after oral inoculation (HAI), bradyzoites were found in cells of the surface epithelium and the lamina propria of the small intestine, primarily the ileum. Division into two tachyzoites was first observed at 18 HA1 in the intestine. At 24 HAI, organisms were also seen in mesenteric lymph nodes. Organisms were first detected in the brain at six days after oral inoculation with bradyzoites (DAI) but not consistently until 10 DAI. Immunohistochemical staining with bradyzoite specific (BAG-5 antigen) anti-serum showed that bradyzoites retained their BAG-5 reactivity even after the first division into two tachyzoites in the intestine at 18 HAL BAG-5 positive organisms were not seen 2–5 DAI. BAG-5 antigens reappeared in T. gondii at 6 DAI. Whole mice and individual tissues of mice fed bradyzoites were bioassayed in cats and mice for the presence of bradyzoites. Feces of cats fed murine tissues were examined for oocyst shedding for short prepatent periods. Bradyzoites were present in the intestines of mice up to 12 HA1 but not at 18 HAI, and tachyzoites and not bradyzoites disseminated to other tissues from the intestine. Bradyzoites were again detected 6 DAI. Using the mouse bioassay, T. gondii was first detected in peripheral blood at 24 HA1 and more consistently at 48 HAL Using a pepsin-digestion procedure and mouse bioassay, organisms were demonstrated in many tissues of mice 15 and 49 DAI.     

Nippostrongylus brasiliensis: malabsorption in experimentally infected rats

Glucose absorption and net small intestinal water movement were examined in rats infected with Nippostrongylus brasiliensis at Days 4, 6, 9, 13, and 19 after inoculation. Rats were infected with 4 X 10(3) N. brasiliensis third stage larvae. The entire small intestine was divided into three segments and each segment perfused simultaneously in vivo with Krebs-Ringer phosphate buffer containing 80 mM glucose, 6 X 10(5) dpm/ml [3H]glucose, and 6.2 X 10(3) dpm/ml [14C]polyethylene glycol. Rats perfused on Days 6, 9, 13, and 19 after inoculation showed a significant (P less than 0.05) decrease in glucose absorption rates from all three segments of the small intestine when compared to uninfected controls. In the three segments of uninfected rat small intestine and those perfused on Days 4, 13, and 19 after inoculation, net absorption of water occurred. However, in the proximal and distal segments perfused on Day 6 and the proximal segment perfused on Day 9, net water movement into the lumen occurred. This is the first report of depressed glucose absorption along the entire length of the small intestine during nippostrongylosis and contradicts previous reports of unaltered net glucose absorption in response to this parasite.     

The helminth parasites of the wild rabbit Oryctolagus cuniculus and their effect on host condition in Dunas de Mira, Portugal

The present study focuses on the helminth parasite community of the wild rabbit in a sand dune area in Portugal over a 5-year period. The influence of host sex and year on the composition of the helminth community is assessed, along with the potential effect of the detected helminths on host body condition. The basic structure of the helminth community comprises Mosgovoyia ctenoides, Graphidium strigosum, Trichostrongylus retortaeformis, Nematodiroides zembrae and Passalurus ambiguus. Mean intensities of G. strigosum varied between years. General G. strigosum intensities were also found to vary according to both year and host sex, but not according to the interaction of both factors. When assessing the effect of helminths on rabbit body condition (expressed by the kidney fat index), higher burdens of M. ctenoides, a cestode that presents a relatively large body mass, were found to induce a reduction in rabbit condition.     

Oocyst-induced Toxoplasma gondii infections in cats

To investigate the oocyst-induced cycle with a 21+ day prepatent period, 32 cats were fed 5 x 10(5) to 2 x 10(7) sporulated oocysts of Toxoplasma gondii and necropsied between 4 hr and 41 days thereafter. The presence of the earliest stages in 7 cats was tested in mice. The tissues of 25 cats were studied histologically; 17 were bioassayed by feeding them to cats to determine, by the length of the prepatent period, whether bradyzoites were present. Based on previous studies, a short (3-10 days) prepatent period indicated that bradyzoites were present in an oral inoculum and a long (greater than 21 days) prepatent period indicated the presence of tachyzoites only. Tissues from 14 cats were also bioassayed in mice for the presence of bradyzoites, using their resistance to pepsin as indicator. Six were studied by both methods. Based on these criteria, tachyzoites predominated in extraintestinal organs during the first 14 days after infection. They were found as early as 4 hr in mesenteric lymph nodes where their number reached 10(4) after 6 and 9 days; they were present after 1 day in all levels of the small intestine and after 6 days in the liver, lung, and blood. Bradyzoites were first detected 10 days after oocyst feeding; they predominated by the third week of infection and were present up to 41 days. Enteroepithelial stages were found histologically only in 2 cats, 24 and 41 days after inoculation.(ABSTRACT TRUNCATED AT 250 WORDS)     

The Endogenous Development of Eimeria alabamensis Christensen, 1941, an Intranuclear Coccidium of Cattle

SUMMARY. The endogenous development of the life cycle of Eimeria alabamensis Christensen, 1941, occurs in the nucleus of the intestinal cells of cattle. Calves were killed at various intervals after inoculation with infective oöcysts to study the endogenous cycle. Excysted sporozoites were found in the contents or scrapings from the walls of rumen, omasum, small intestine, cecum, and colon. They were found in the cytoplasm of intestinal epithelium at 2 days. Schizonts were found in the nuclei beginning at 2 days, but the number was low by the 8th day. Merozoite numbers usually ranged between 16 and 32. Some host nuclei contained as many as 48 or more, but these appeared to be the result of more than one schizont merging in the same host nucleus. Merozoites were slender, spindle-shaped bodies while still in the schizont walls, but were short with bluntly rounded tips when found in intracellular spaces and crypts. Gametocytes were found as early as the 4th day. Most of the stages of gametogenesis were limited to the lowest third of the small intestine, but in heavy infections some were also found in the cecum and upper colon. Microgametocytes were multinucleate and were more densely stained than the uninucleate macrogametocytes. The ratio of macrogametocytes to microgametocytes in 100 gametes was 78: 22. Oöcysis with "shells" were found in sections of the lower 20 feet of the ileum on the 6th day, which coincided with the shortest prepatent period reported previously. As many as three schizonts or microgametocytes or four or five macrogametocytes or oöcysts could be found in the same host nucleus. The variations in shape of the oöcysts appeared to be dependent on the number of oöcysts crowded into each nucleus.     

Life Cycle and Mating Behavior of Belonolaimus longicaudatus in Gnotobiotic Culture

The life cycle of Belonolaimus longicaudatus was observed in vitro on excised roots of Zea mays. Roots were cultured on Gamborg''s B5 medium in petri dishes with 1.5% agar adjusted to pH 5.8 and incubated at 28 °C in darkness. Second-stage juveniles (J2) fed on the roots and started the second molt (M2) to the third-stage juveniles 2 days after inoculation (DAI). The third molt (M3) to the fourth-stage juveniles occurred 7 DAI, followed by the fourth molt (M4) to males 13 DAI or to females 14 DAI. Nematode gender differences were observed by the end of the fourth molt. The first male appeared 15 DAI and the first female 17 DAI, after which mating occurred. Males were attracted to females, and mating was observed. Mating was required for reproduction. Fertilized females began to lay eggs 19 DAI and continued egg laying without the further presence of males during a 90-day observation. All of the eggs hatched. Unfertilized females rarely laid eggs, and none of the eggs were able to hatch. Feeding took place between each molt and before egg deposition occurred. The first-stage juveniles molted in the eggs 4 days after deposition, and J2 hatched from eggs 5 days after egg deposition. The life cycle from J2 to J2 was completed in 24 days.     

Experimental Studies of the Life Cycle of Leucocytozoon simondi in Ducks in Norway*

SYNOPSIS. Pekin ducks were infected naturally and experimentally. The life cycle of Leucocytozoon simondi was followed in the ducks and the vector, a new species of Simulium, close to Simulium dogieli. The prepatent period in the ducks was 4–5 days and developing megaloschizonts appeared in 6–7 days. Schizonts were found in liver, spleen, brain, and kidney. In the kidneys they were located in the glomeruli. Sporogony in some individuals was completed in 7 days at 13–14 C, other individuals developed more slowly, as ookinetes were found in flies 8 days after feeding. The rapid asexual cycle combined with a sporogonic cycle, in which some ookinetes develop rapidly and others more slowly, favors the maintenance of the parasite in an environment with relatively low daily temperatures. This and the size of the megaloschizonts indicate differences between this strain of the parasite and the one occurring in North America.