Leishsmania (Leishmania) amazonensis infection: Muscular involvement in BALB/c and C3H.HeN mice

Recent studies have provided some insights into Leishsmania (Leishmania) amazonensis muscular infection in dogs, although, muscular disease due to leishmaniasis has been poorly documented. The aim of our study was to evaluate involvement of Leishmania in muscular infection of two distinct mouse strains (BALB/c and C3H.He), with different genetic backgrounds. BALB/c mice, susceptible to Leishmania infection, showed, at the beginning of infection, a great number of infected macrophages among muscle fibers; however, in C3H.He resistant mice, muscle fibers were less damaged than in BALB/c mice, but some parasitized macrophages could be seen among them. A follow up of the infection showed an intense inflammatory infiltrate mainly composed of infected macrophages in BALB/c muscles and the presence of amastigotes within muscle fibers; while C3H.He mice exhibited a moderate inflammatory infiltrate among skeletal muscle fibers and an absence of amastigotes. Total destruction of muscles was observed in BALB/c mice in the late phase of infection (day 90) while C3H.He mice showed a process of muscle repair. We concluded that: (1) the muscles of BALB/c mice were more affected by leishmaniasis than those of C3/H.He mice; (2) Leishmania amastigotes are capable of infecting muscular fibers, as observed in BALB/c mice; (3) as inflammatory infiltrate is less intense in C3H.He mice these animals are capable of restoring muscular fibers.     

Fasciola hepatica: Comparative studies on fascioliasis in rats and mice

Chapman C. B. and Mitchell G. F. 1982. Fasciola hepatica: comparative studies on fascioliasis in rats and mice. International Journal for Parasitology12: 81–91. Certain characteristics of infection differ between rats and mice exposed to metacercariae of the trematode parasite, Fasciola hepatica. Rats develop a degree of age-related resistance (and infected older females contain fewer parasites than older males), resistance to reinfection in infected rats is demonstrated readily though is partial, and a comparable degree of resistance can be obtained in recipients of infected rat serum provided the serum is given at about the time of challenge. None of these features of F. hepatica infection is seen in mice. Rats also differ from mice in that they can be vaccinated against infection (although again, resistance is incomplete) using larval antigen mixtures in adjuvants. Mice do respond to infection by production of antilarval antibodies and a slight IgG₁ hypergammaglobulinaemia and larvae will sensitize mice for delayed hypersensitivity. The results of this study indicate that sera from infected rats versus infected mice will be useful in pinpointing antigens of F. hepatica larvae which are involved in expression of partial host protection.     

Studies on Anoplotaenia dasyuri Beddard, 1911 (Cestoda: Taeniidae), a parasite of the Tasmanian devil: Observations on the egg and metacestode

The ultrastructure and hatching mechanisms of the egg of Anoplotaenia dasyuri showed minor differences from those of other taeniid species. The embryophore disintegrated under the action of pepsin, but activity of the embryo did not occur until placed in an alkaline solution containing pancreatin. The addition of bile from various host species did not affect the hatching of eggs of A. Daysuri although it did increase the rate of hatching of eggs of Taenia pisiformis. Metacestodes were recovered from the hearts of experimentally infected possums (Trichosurus vulpeculd), kangaroos (Macropus giganteus and M.fuliginosus) and from the livers of mice and guinea pigs fed eggs of A. Daysuri. A wombat (Vombatus ursinus), rats and rabbits could not be infected orally. Hatched and activated embryos, injected intravenously, developed in the hearts of kangaroos and wallabies (M. rufogriseus), the livers, lungs, kidneys and hearts of mice, but not at all in rats and rabbits. Similarly, injections of embryos into the portal veins of mice, rats and rabbits resulted in development of metacestodes in the lungs and liver of mice only. The development of some stages of the metacestode are briefly described and the possible phylogeny of the parasite discussed.     

Plasmodium berghei: Specific stimulation of rat lymphocytes by soluble antigens released in vitro from infected erythrocytes

Soluble components released in vitro from rat erythrocytes parasitized with Plasmodium berghei have been shown to stimulate nonadherent spleen lymphocytes from rats convalescent from homologous infection. The active product is released from the infected erythrocytes either spontaneously during incubation, or as the result of artificial rupture of infected erythrocytes by freezing and thawing or sonication. This antigen produced precipitation lines with antiplasmodial antibodies from sera of convalescent and hyperimmune rats and from immunized rabbits.     

Experiments on the transmission of Babesia divergens to cattle by the tick Ixodes ricinus

A modification of the method of rearing Ixodes ricinus gave a successful method of producing and reliably rearing adequate numbers of this tick for experimental work.Experiments on transmission of Babesia divergens by I. ricinus showed that infections could be initiated only in the adult stage of the tick. Whilst all stages of the F₁ generation of an infected female could transmit infection, larvae and nymphs could not acquire it. Infection persisted throughout the F₁ generation and sometimes up to the F₂ larval stage even when the ticks were maintained on hosts not susceptible to B. divergens. Both parasitaemic and premune carrier hosts were infective to ticks. A single infected adult or nymph could transmit infection.     

Interactions between Oncopera alboguttata (Lepidoptera: Hepialidae) and its microsporidan pathogen, Pleistophora oncoperae (Protozoa: Microsporida)

Infection by Pleistophora oncoperae is widespread in populations of Oncopera alboguttata. Detailed study of insects from one site indicated that 85% of the 131 pupae and 65% of the 403 adults were infected. The infection did not adversely affect duration of larval and pupal development, adult life span, the number of eggs laid, or fecundity. Infected females were able to transmit the disease to their progeny, though the degree of transmission ranged from 0 to 92%, depending on the severity of the parental infection. Transmission of the disease by infected males could not be detected. It was estimated that 49% of the progeny from this site would have been infected by transovum transmission. Details of the incidence of P. oncoperae infection from this area during the period 1972 to 1979 are given to emphasise the possible role of this disease in O. alboguttata population dynamics.     

Eimeria meleagrimitis, E. adenoeides, and E. dispersa: Severity of infection and changes in the intestinal mucosa of the Turkey

Glucose and methionine were malabsorbed in some intestinal regions of turkeys infected with Eimeria meleagrimitis, E. adenoeides, or E. dispersa. The decrease in absorption was not always related to the numbers of parasites in the cells or the extent of damage to the mucosa. With E. adenoeides, malabsorption was found in the jejunum even though parasites were not present. Conversely, with E. dispersa, no malabsorption was observed in the duodenum even though light microscopy showed numerous parasites. In many intestinal regions, damage to the mucosal surface visible with scanning electron microscopy (SEM) was slight or absent, although malabsorption was marked. No changes were noted with SEM in the structure and orientation of the brush border in these regions. Villar height was significantly reduced in the regions of heaviest infection when intestinal damage was visible. Conversely, the crypts of Lieberkühn were often two or three times as deep in infected poults as in uninfected poults. In general, no differences were found in the thickness of the circular and longitudinal muscle layers between the infected and uninfected poults. The dry weight of the intestinal tissue was less from infected poults than from uninoculated controls and was related to both region of the intestine and severity of the infection.     

Eimeria nieschulzi and Trichinella spiralis: Analysis of concurrent infection in the rat

The effects of concurrent primary infection of the rat with Eimeria nieschulzi and Trichinella spiralis on the number of oocysts of E. nieschulzi shed by the host and on the number, distribution, and fecundity of adult T. spiralis were analyzed. When rats were initially infected with E. nieschulzi followed 9 days later by infection with T. spiralis there occurred a significant decrease in the total numbers of adult worms in the small intestine, a significant shift in the position of these worms along the length of the small gut, a decrease in the fecundity of adult female worms, and a decrease in muscle parasitism when compared with rats infected with T. spiralis alone. When rats were initially infected with T. spiralis, followed 9 days later by infection with E. nieschulzi, there occurred a significant decrease in the numbers of oocysts shed over 24 hr on Days 7, 9, and 11 postinfection below that seen with rats infected only with Eimeria. These changes are discussed in terms of the enteropathophysiologic lesions and enteric inflammation known to occur during infections with these two parasites.     

Studies on Trypanosoma vivax: Transmission of mouse infective T. vivax by tsetse flies

Glossina morsitans and G. tachinoides were successfully infected with 2 isolates of Trypanosoma vivax which had an inherent property for serial maintenance in mice. The infection rate in the flies was relatively high. Cyclical transmission of these isolates from sheep to sheep and from goat to goat was achieved and did not affect the property of the isolates to infect mice. Mice were not apparently suitable for direct fly transmission experiments of T. vivax.     

Protection against Mesocestoides corti infection in mice treated with zymosan or Salmonella enteritidis 11RX

Toye P. G. and Jenkin C. R. 1982. Protection against Mesocestoides corti infection in mice treated with zymosan or Salmonella enteritidis 11RX. International Journal for Parasitology12: 399–402. Zymosan and Salmonella enteritidis 11RX were found to partially protect mice against infection with the cestode Mesocestoides corti. Thus, mice previously infected with S. enteritidis 11RX contained fewer parasites in the peritoneal cavity compared to normal mice. Mice pretreated with zymosan contained fewer parasites in the peritoneal cavity and in the liver compared to normal mice and this protection was enhanced by the passive transfer of serum from mice chronically infected with M. corti. Examination of mice in the initial stages of infection revealed that the administration of zymosan led to an alteration in parasite location from the peritoneal cavity to the liver.     

Isolation of Fasciola hepatica genus-specific antigens

Santiago de Weil N., Hillyer G. V. and Pacheco E. 1984. Isolation of Fasciola hepatica genus-specific antigens. International Journal for Parasitology14: 197–206. The Fasciola hepatica antigens which induce antibody formation in acute fascioliasis were isolated by acid elution after reacting an F. hepatica tegument antigen extract with a CNBr-Sepharose 4B column coupled with IgG obtained from the serum of rabbits infected with fascioliasis for 6–10 weeks. These isolated antigens were further separated by gel filtration using a column packed with Sephacryl S-200. In this manner three major peaks were obtained. The best serologic antigens were found in peak 2 which had a mol. wt range of 14,000–43,000. This peak contains genus-specific F. hepatica antigens which are highly reactive with fascioliasis serum. These antigens do not cross-react with either Schistosoma mansoni or with bovine serum albumin by gel diffusion. Monitoring by ELISA and gel diffusion with heterologous and homologous antisera showed that as purification by antibody affinity chromatography proceeded, cross reactivity with S. mansoni was eliminated. The rabbit antiserum obtained against peak 2, when tested by immunoelectrophoresis with a crude F. hepatica extract shows one main band identical to the main band observed with serum from acutely infected rabbits. Up to two other minor bands can be detected using concentrated homologous antisera. Fractions obtained from preparative iso-electric focusing of the F. hepatica tegument extract were reacted with sera from rabbits with acute fascioliasis. Two main bands were observed in immunodiffusion with antigens eluting in a pH range of 7.4–8.7. When these fractions were monitored with anti peak 2 antisera, two precipitin bands appeared with antigens eluting in a pH range of 7.4–7.9. The F. hepatica genus-specific antigen pool was applied to ELISA to evaluate its ability to detect antibody in a primary F. hepatica infection in rabbits. A rise in absorbance values could be detected by 2 weeks of infection, reached high levels by 6 weeks and remained high through 28 weeks of infection.     

Trypanosoma cruzi: Effect on B-cell-responsive and -responding clones

During the course of Trypanosoma cruzi infection in C57BL/6 mice, which are relatively resistant to the parasite, the hosts developed antibody activity against previously unencountered antigens. The anti-sheep erythrocyte and antitrinitrophenyl antibody levels increased rapidly from Day 7 of infection, reached a peak by the 21st day, and were maintained at this level through 120 days postinfection in these mice. In contrast, highly susceptible C3H(He) mice did not have demonstrable antibody responses to SRBC or TNP during the 24-day infection period. Autoantibody activity against the selfantigens presented on isologous erythrocytes or thymocytes, however, were reduced in infected C57BL/6 mice. No significant reduction in autoreactivity to the self-antigens on erythrocytes or thymocytes was observed in C3H(He) mice infected with T. cruzi although a trend of reduced autoresponsiveness toward erythrocytes appeared to be developing by the time of death. C57BL/6 mice immunized with sheep erythrocytes as neonates and infected with T. cruzi as adults, or adult mice primed with low doses of sheep erythrocytes prior to infection, had elevated antibody responses to sheep erythrocytes unless the mice were immunized with sheep erythrocytes during the course of infection, in which case suppression of the response against sheep erythrocytes resulted. The nonspecific synthesis of immunoglobulins in infected C57BL/6 mice was, in part, a result of the lymphocyteactivating properties of T. cruzi-associated antigens. The T. cruzi-associated antigens induced proliferative and differentiative responses in spleen cells in vitro. It is proposed that the T. cruzi-associated antigens differentially affect lymphocytes capable of responding to antigen and those lymphocytes previously stimulated by antigen.     

Comparison of rapid expulsion of Trichinella spiralis in mice and rats

Alizadeh H. and Wakelin D. 1982. Comparison of rapid expulsion of Trichinella spiralis in mice and rats. International Journal for Parasitology12: 65–73. Primary infections of Tricliinella spiralis in both NIH mice and Wistar rats resulted in increased levels of mucosal mast cells and goblet cells. In mice the numbers of both cell types rose sharply before worm expulsion (days 8–10), remained at an increased level for a short time and declined quickly, reaching control levels on day 14 for goblet cells and between days 28 and 35 for mast cells. In contrast, in rats, the numbers of goblet cells and mast cells increased during worm expulsion and remained above control levels for a prolonged period. Challenge infections given shortly after expulsion of a primary infection (day 14) were expelled rapidly, worm loss being virtually complete with 24 h. In mice this response to challenge was short-lived and persisted only until day 16 after primary infection. After this time, challenge worms were expelled more slowly after infection. In rats the rapid expulsion response was expressed for at least 7 weeks after primary infection. Mice and rats showed differences in the conditions of infection necessary to prime for rapid expulsion, mice requiring larger and longer duration primary infections, but the expression of the response appeared to be similar in both species. In mice it was shown that rapid expulsion of T. spiralis was a response evoked specifically by prior infection with this species; infections with other intestinal nematodes had no effect. Similarly, the effect upon challenge infection was also specific to T. spiralis. The rapidity with which challenge infections are expelled suggests that either the specific inflammatory changes generated during primary infection result in an environment that is unsuitable for establishment of subsequent infections or that challenge infections provide a stimulus that can provoke an almost instantaneous response in the primed intestine. The relationship of the observed cellular changes to such mechanisms is discussed.     

Toxoplasma gondii: Effects of Artemisia annua L. on susceptibility to infection in experimental models in vitro and in vivo

Considering that the treatment for toxoplasmosis is based on drugs that show limited efficacy due to their substantial side effects, the purpose of the present study was to evaluate the effects of Artemisia annua on in vitro and in vivo Toxoplasma gondii infection. A. annua infusion was prepared from dried herb and tested in human foreskin fibroblasts (HFF) or mice that were infected with the parasite and compared with sulfadiazine treatment. For in vitro experiments, treatment was done on parasite before HFF infection or on cells previously infected with T. gondii and the inhibitory concentration (IC₅₀) values for each treatment condition were determined. Viability of HFF cells in the presence of different concentrations of A. annua infusion and sulfadiazine was above 72%, even when the highest concentrations from both treatments were tested. Also, the treatment of T. gondii tachyzoites with A. annua infusion before infection in HFF cells showed a dose-response inhibitory curve that reached up to 75% of inhibition, similarly to the results observed when parasites were treated with sulfadiazine. In vivo experiments with a cystogenic T. gondii strain demonstrated an effective control of infection using A. annua infusion. In conclusion, our results indicate that A. annua infusion is useful to control T. gondii infection, due to its low toxicity and its inhibitory action directly against the parasite, resulting in a well tolerated therapeutic tool.     

A potential association between Toxoplasma gondii infection and schizophrenia in mouse models

Schizophrenia is a serious neuropsychiatric disease of uncertain etiology, which causes human mental disorder and affects about 1% of the population. In recently years, some studies showed that some cases of schizophrenia may be associated with Toxoplasma gondii infection. In order to investigate a potential association between Toxoplasma infection and schizophrenia, we investigated the relative clinical symptom of schizophrenia such as learning and memory capability, depression and stereotypy to find some useful information by behavioral test in mouse models. Our results demonstrated that mice from Toxoplasma infection and MK-801 administration (as the model of schizophrenia) were impaired in learning and memory capability, and they had more serious depression and stereotypy compared with the control mice, especially the mice from congenital Toxoplasma infection. In addition, our results clearly showed that the number of cysts in brain tissue of congenital Toxoplasma infection mice was significantly low than in acquired Toxoplasma infected mice. Collectively, these results suggested a potential association between Toxoplasma infection and schizophrenia.     

The Effect of C. burnetii Infection on the Cytokine Response of PBMCs from Pregnant Goats

In humans, infection with Coxiella burnetii, the causative agent of Q fever, leads to acute or chronic infection, both associated with specific clinical symptoms. In contrast, no symptoms are observed in goats during C. burnetii infection, although infection of the placenta eventually leads to premature delivery, stillbirth and abortion. It is unknown whether these differences in clinical outcome are due to the early immune responses of the goats. Therefore, peripheral blood mononuclear cells (PBMCs) were isolated from pregnant goats. In total, 17 goats were included in the study. Six goats remained naive, while eleven goats were infected with C. burnetii. Toll-like receptor (TLR) and cytokine mRNA expression were measured after in vitro stimulation with heat-killed C. burnetii at different time points (prior infection, day 7, 35 and 56 after infection). In naive goats an increased expression of interleukin (IL)-1β, tumor necrosis factor (TNF)-α, IL-10 and interferon (IFN)-γ mRNA upon C. burnetii stimulation was detected. In addition, TLR2 expression was strongly up-regulated. In goats infected with C. burnetii, PBMCs re-stimulated in vitro with C. burnetii, expressed significantly more TNF-α mRNA and IFN-γ mRNA compared to naive goats. In contrast, IL-10 mRNA production capacity was down-regulated during C. burnetii infection. Interestingly, at day 7 after inoculation a decreased IFN-γ protein level was observed in stimulated leukocytes in whole blood from infected goats, whereas at other time-points increased production of IFN-γ protein was seen. Our study shows that goats initiate a robust pro-inflammatory immune response against C. burnetii in vitro. Furthermore, PBMCs from C. burnetii infected goats show augmented pro-inflammatory cytokine responses compared to PBMCs from non-infected goats. However, despite this pro-inflammatory response, goats are not capable of clearing the C. burnetii infection.     

Mycoplasma agalactiae detected in the semen of goat bucks

Contagious agalactia (CA) is among the most significant diseases affecting small ruminant populations in Mediterranean countries. This study was designed to detect the excretion in semen of CA-causing mycoplasmas in goats (Capra hircus) reared in Spain, where the disease is considered endemic. Culture techniques and PCR were conducted on 147 semen samples collected from 113 goat bucks to detect mycoplasmas. No animal showed clinical symptoms of CA at the moment of the screening. M. agalactiae was identified using both diagnostic methods in three semen samples collected from three different bucks. These animals belonged to a group of animals in which semen had been analyzed twice and only the second sample proved positive, suggesting the possibility of intermittent excretion. This is the first report of the isolation of M. agalactiae from semen collected from naturally infected goats. Future studies should investigate whether semen could be a real source of CA infection by determining if the agent may be transmitted during natural service or when semen is used for artificial insemination.     

Transmission of ‘Candidatus Anaplasma camelii’ to mice and rabbits by camel-specific keds,Hippobosca camelina

Anaplasmosis, caused by infection with bacteria of the genus Anaplasma, is an important veterinary and zoonotic disease. Transmission by ticks has been characterized but little is known about non-tick vectors of livestock anaplasmosis. This study investigated the presence of Anaplasma spp. in camels in northern Kenya and whether the hematophagous camel ked, Hippobosca camelina, acts as a vector. Camels (n = 976) and > 10,000 keds were sampled over a three-year study period and the presence of Anaplasma species was determined by PCR-based assays targeting the Anaplasmataceae 16S rRNA gene. Camels were infected by a single species of Anaplasma, ‘Candidatus Anaplasma camelii’, with infection rates ranging from 63–78% during the dry (September 2017), wet (June-July 2018), and late wet seasons (July-August 2019). 10–29% of camel keds harbored ‘Ca. Anaplasma camelii’ acquired from infected camels during blood feeding. We determined that Anaplasma-positive camel keds could transmit ‘Ca. Anaplasma camelii’ to mice and rabbits via blood-feeding. We show competence in pathogen transmission and subsequent infection in mice and rabbits by microscopic observation in blood smears and by PCR. Transmission of ‘Ca. Anaplasma camelii’ to mice (8–47%) and rabbits (25%) occurred readily after ked bites. Hence, we demonstrate, for the first time, the potential of H. camelina as a vector of anaplasmosis. This key finding provides the rationale for establishing ked control programmes for improvement of livestock and human health.     

Babesia hylomysci and Babesia microti: Dexamethasone treatment of infected mice

The effect of dexamethason on Babesia hylomysci and B. microti was investigated in LACA mice. The drug enhanced both infections by depressing the immune mechanisms of the host when treatment was initiated before parasite inoculation, but had no effects on established and subpatent infections. The degree of parasitemia in the treated mice seemed to depend on the tropism of either parasite toward mature erythrocytes or reticulocytes. B. hylomysci, which favors mature erythrocytes, produced fulminating infections in treated mice. B. microti, which prefers reticulocytes, produced similar parasitemia patterns in treated and untreated mice, but only the treated mice succumbed to the infection. The drug, which suppressed cellular proliferation in the spleens of infected animals, together with its direct lympholytic effects, drastically changed the architecture of the organ.     

Nippostrongylus brasiliensis and Nematodirus battus: Changes in numbers and weight during the course of infection

Nematodirus battus has been shown to be subject to a “self-cure” mechanism when lambs 6 weeks of age are infected with 60,000 larvae. It is proposed that this self-cure phenomenon is an immune response similar to that which occurs in rats infected with Nippostrongylus brasiliensis. Changes in the weight of adult Nematodirus sp. and Nippostrongylus sp. occur over the period of an infection in their hosts. Females of both species from high-dose infections increased in weight up to that time postinfection where most adult worms were present, then decreased in weight with the onset of rejection from the host. Male Nematodirus sp. showed a similar pattern of weight change to that of females but male Nippostrongylus sp. maintained a steady weight throughout the infection. The consequences of these changes in weight are discussed with relevance to expression of enzyme activities of the nematodes on a weight of individual nematode basis.