Contrasting microbiota profiles observed in children carrying either Blastocystis spp. or the commensal amoebas Entamoeba coli or Endolimax nana

Recent studies have shown how intestinal parasites can modulate gut microbiota. This observation is not surprising since the human intestinal lumen, like any other niche, is a battlefield of microbial competition, and Eukaryotes can affect bacterial populations. Intestinal pathogenic protist has been associated with reshaping the microbial community structure; however, the interactions between the colonic bacterial communities and parasites like Blastocystis spp., Entamoeba coli, and Endolimax nana have been poorly studied. In this work, we studied the distal intestinal bacterial microbiota of 49 children attending 7 public daycare centers in Medellin, Colombia, and compared the bacterial microbiota structure in the presence or absence of the protists Blastocystis spp., E. coli, and E. nana. Parasite colonization was associated with an increase in bacterial richness. Moreover, Blastocystis spp. presented a positive relationship with Prevotella, since this bacterium was selectively enriched in children carrying it. Remarkably, the E. coli colonized children showed a microbial profile that was closer to uninfected controls, although some bacterial taxa displayed to be enriched. This is the case for Akkermansia, which showed to be favored in E. coli colonized individuals, while notably reduced in the Blastocystis spp. parasitized group.

Experimental demonstration of the possible role of Acanthamoeba polyphaga in the infection and disease progression in Buruli Ulcer (BU) using ICR mice

The transmission of Buruli ulcer (BU), caused by Mycobacterium ulcerans (MU), remains puzzling although a number of hypothesis including through bites of infected aquatic insects have been proposed. We report the results of experiments using ICR mice that give credence to our hypothesis that Acanthamoeba species may play a role in BU transmission. We cocultured MU N2 and MU 1615 which expresses red fluorescent protein (RFP) and Acanthamoeba polyphaga (AP), and confirmed infected AP by Ziehl-Neelsen (ZN) staining. We tested for viability of MU inside AP and observed strong RFP signals inside both trophozoites and cysts after 3 and 42 days of coculturing respectively. ICR mice were topically treated, either on shaved intact or shaved pinpricked rumps, with one of the following; MU N2 only (2.25 x 106 colony forming units [CFU] / ml), MU N2:AP coculture (2.96 x 104 CFU: 1.6 x 106 cells/ml), AP only (1.6 x 106 cells/ml), PYG medium and sterile distilled water. Both MU N2 only and MU N2:AP elicited reddening on day (D) 31; edema on D 45 and D 44 respectively, and ulcers on D 49 at pinpricked sites only. To ascertain infectivity and pathogenicity of MU N2 only and MU N2:AP, and compare their virulence, the standard mouse footpad inoculation method was used. MU N2:AP elicited reddening in footpads by D 3 compared to D 14 with MU N2 only of the same dose of MU N2 (2.96 x 104 CFU). ZN-stained MU were observed in both thin sectioned and homogenized lesions, and aspirates from infected sites. Viable MU N2 were recovered from cultures of the homogenates and aspirates. This study demonstrates in ICR mice MU transmission via passive infection, and shows that punctures in the skin are prerequisite for infection, and that coculturing of MU with AP enhances pathogenesis.

War on terror cells: killing the host that harbours 'superbugs' is an infection control strategy in our fight against infectious diseases

It is proposed that targeting the environmental host that harbour 'superbugs' is an effective strategy in our fight against infectious diseases.

Survey of Naegleria fowleri in geothermal recreational waters of Guadeloupe (French West Indies)

In 2008 a fatal case of primary amoebic meningoencephalitis, due to the amoeboflagellate Naegleria fowleri, occurred in Guadeloupe, French West Indies, after a child swam in a bath fed with geothermal water. In order to improve the knowledge on free-living amoebae in this tropical part of France, we investigated on a monthly basis, the presence of Naegleria spp. in the recreational baths, and stream waters which feed them. A total of 73 water samples, 48 sediments and 54 swabs samples were collected from 6 sampling points between June 2011 and July 2012. The water samples were filtered and the filters transferred to non-nutrient agar plates seeded with a heat-killed suspension of Escherichia coli while sediment and swab samples were placed directly on these plates. The plates were incubated at 44°C for the selective isolation of thermophilic Naegleria. To identify the Naegleria isolates the internal transcribed spacers, including the 5.8S rDNA, were amplified by polymerase chain reaction and the sequence of the PCR products was determined. Thermophilic amoebae were present at nearly all collection sites. The pathogenic N. fowleri was the most frequently encountered thermophilic species followed by N. lovaniensis. The concentration of N. fowleri was rather low in most water samples, ranging from 0 to 22 per liter. Sequencing revealed that all N. fowleri isolates belonged to a common Euro-American genotype, the same as detected in the human case in Guadeloupe. These investigations need to be continued in order to counsel the health authorities about prevention measures, because these recreational thermal baths are used daily by local people and tourists.

Balamuthia amoebic encephalitis: An emerging disease with fatal consequences

Balamuthia amoebic encephalitis (BAE), caused by the protozoan pathogen, Balamuthia mandrillaris, is a serious human disease with fatal consequences and a mortality rate of more than 95%. A key factor that contributes to the high mortality is the incomplete understanding of its pathogenesis and pathophysiology. The most distressing aspect is that the high level of mortality is due to lack of awareness combined with the lack of effective drugs. Early diagnosis followed by aggressive treatment may lead to cure. Several lines of evidence suggest that BAE develops as a result of haematogenous spread, but it is unclear how circulating amoebae enter the central nervous system and cause inflammation, blood-brain barrier disruption and neuronal injury. Recent studies have identified several parasite-host determinants for B. mandrillaris translocation of the blood-brain barrier, and host inflammatory markers that may be associated with neuronal injury. These determinants may provide important targets for the prevention and treatment of BAE. Here, we present a brief overview of the current understanding of the pathogenesis and pathophysiology of BAE, available diagnostic methods, possible therapeutic interventions and biology of the causative agent.

Microfauna associated with amoebic gill disease in sea-farmed Atlantic salmon, Salmo salar L., smolts

A study of microfauna, associated with pathological changes in the gills of Atlantic salmon, Salmo salar L., was conducted over 2001-2002. Monthly samples of 1(+) salmon smolts were taken, protozoan populations were quantified and gill health was assessed histologically. Protozoan densities were correlated with pathological changes, in order to determine their possible role in lesions in the gills. The most severe gill tissue changes were observed in summer/autumn and the least in spring. A diverse polyphyletic protozoan community was observed colonizing the gills, including Neoparamoeba sp., other amoebae, scuticociliates, Ichthyobodo-like flagellates, trichodinid ciliates and prostomatean ciliates. The earlier gill tissue changes in the gill were not always associated with the presence of these microorganisms, whereas amoebae (other than Neoparamoeba sp.), Ichthyobodo-like flagellates and trichodinid ciliates correlated with augmenting gill lesions. Neoparamoeba sp. was present, but its abundance did not correlate with the disease. This study suggests that a diversity of protozoans including Ichthyobodo-like flagellates, trichodinid ciliates and amoebae other than Neoparamoeba sp. are involved in the aetiology of amoebic gill disease in the Irish situation.

Ameba-associated microorganisms and diagnosis of nosocomial pneumonia

Ameba-associated microorganisms should be suspected when conventional microbiologic test results are negative.

To elucidate the role of ameba-associated microorganisms (AAMs) as etiologic agents of pneumonia, we screened for Legionella spp., Parachlamydia acanthamoeba, Afipia sp., Bosea spp., Bradyrhizobium spp., Mesorhizobium amorphae, Rasbo bacterium, Azorhizobium caulinodans, Acanthamoeba polyphaga mimivirus, and conventional microorganisms in 210 pneumonia patients in intensive-care units by using culture, polymerase chain reaction, and serologic testing. These resulted in 59 diagnoses in 40 patients. AAMs and non-AAMs were implicated in 10.5% of the patients. The infectious agents were identified in 15 patients: Acanthamoeba polyphaga mimivirus, 8; Legionella pneumophila, 3; L. anisa, 1; Parachlamydia sp., 1; Bosea massiliensis, L. worsleiensis, L. quinlivanii, and L. rubrilucens, 1; and M. amorphae and R. bacterium, 1. A. polyphaga mimivirus was the fourth most common etiologic agent, with a higher seroprevalence than noted in healthy controls. This finding suggested its clinical relevance. Therefore, AAM might cause nosocomial pneumonia and should be suspected when conventional microbiologic results are negative.

Influence of salmonid gill bacteria on development and severity of amoebic gill disease

The relationship between salmonid gill bacteria and Neoparamoeba sp., the aetiological agent of amoebic gill disease (AGD) was determined in vivo. Fish were divided into 4 groups and were subjected to following experimental infections: Group 1, amoebae only; Group 2, Staphylococcus sp. and amoebae; Group 3, Winogradskyella sp. and amoebae; Group 4, no treatment (control). Fish (Groups 1, 2 and 3) were exposed to potassium permanganate to remove the natural gill microflora prior to either bacterial or amoebae exposure. AGD severity was quantified by histological analysis of gill sections to determine the percentage of lesioned filaments and the number of affected lamellae within each lesion. All amoebae infected groups developed AGD, with fish in Group 3 showing significantly more filaments with lesions than other groups. Typically lesion size averaged between 2 to 4 interlamellar units in all AGD infected groups. The results suggest that the ability of Neoparamoeba sp. to infect filaments and cause lesions might be enhanced in the presence of Winogradskyella sp. The possibility is proposed that the prevalence of more severe AGD is due to the occurrence of Winogradskyella sp. at high concentrations on the gills.

Isolation of Acanthamoeba sp. from conjunctival sac of healthy individuals using swab

Is Acanthamoeba sp. normally found in the eyes? A study was carried out to establish the possibility of Acanthamoeba sp. as a part of the normal conjunctival flora. Conjunctiva swabbing were carried out in 286 healthy Orang Asli school children using sterile cotton swab. The swab was then inoculated onto non-nutrient agar (NN-A). Heat killed Escherichia coli that was used as food source for the growth of the amoebae was pipetted onto and away from the smear. The plates were incubated at 30 degrees C and examined daily using an inverted microscope for 14 days. Morphology of the trophozoites and cysts of the amoebae were used as the taxonomic criteria for identification. Positive-controls and negative-controls were done to check for the consistency of the technique used and monitoring of contamination respectively. None of the conjunctiva swab cultured was positive for Acanthamoeba sp. This finding may indicate that Acanthamoeba sp. is not part of normal conjunctival flora or conjunctiva swab is an insensitive technique to isolate the organism. However, a more extensive research is needed to investigate these possibilities.

September 2004: a 6-year-old girl with headache and stiff neck

Free-living amebas in the genera Naegleria, Acanthamoeba and Balamuthia are known to cause CNS infections. Here we report a case of fatal granulomatous amebic meningoencephalitis (GAE) caused by Balamuthia mandrillaris in a 6-year-old previously healthy girl who presented with headache and stiff neck. She was treated medically for brain abscess after a CT scan identified a ring-enhancing lesion in the right temporo-parietal area. A brain biopsy showed necrosis and granulomatous inflammation. Subsequently, multiple new lesions appeared in the brain bilaterally. A second brain biopsy revealed viable amebic trophozoites that were most abundant in perivascular spaces, accompanied by neutrophils, macrophages and eosinophils. Immunofluorescence study confirmed the amoeba as Balamuthia mandrillaris. This case demonstrates that making diagnosis of GAE pre-mortem requires a high index of suspicion. Amebic infection should be included in the differential diagnosis of any granulomatous lesion in CNS; and careful search for amebic parasites should be carried out especially when necrosis predominates in the pathological material.

Pathogenesis of Acanthamoeba infections

Acanthamoeba are free-living, harmless organisms, however, given the opportunity and the appropriate conditions, they can cause painful, sight-threatening as well as fatal infections and, thus, are considered opportunistic pathogens. Acanthamoeba infections have become increasingly important in the past few years due to increasing populations of contact lens users and AIDS patients. The mechanisms associated with the pathogenesis of Acanthamoeba tend to be highly complex, depending on parasite, host and the environmental factors. Elucidation of the biochemical, cellular and molecular basis of the pathogenesis of diseases caused by Acanthamoeba may lead to the development of therapeutic interventions.

Defense mechanisms of IFN-gamma and LPS-primed murine microglia against Acanthamoeba castellanii infection

In the central nervous system (CNS), cytokine-primed microglia play a central role in host's defense against Acanthamoeba castellanii infection. In this study, the effect of recombinant interferon (rIFN)-gamma and Salmonella enterica serovar enteritidis lipopolysaccharide (LPS), both inflammatory stimuli, on A. castellanii infection in murine microglia was examined. Priming of microglia with rIFN-gamma and LPS synergistically triggered, in a dose-dependent manner, amebastatic activity in these cells. More than 52%, 88% or 95% of this function was then abrogated by anti-IL-1beta (but not anti-IL-1alpha), IL-6 or TNF-alpha neutralizing antibodies, suggesting that these endogenously produced cytokines may participate in the antimicrobial capacity. Consistent with these findings, the priming of microglia with rIFN-gamma and LPS elicited the release of proinflammatory interleukin (IL)-1alpha, IL-1beta, IL-6 and tumor necrosis factor (TNF)-alpha. Since L-canavanine affected amebastatic activity only during the priming process but not during the infection process, NO-dependent pathway appears to be not the sole antiparasitic mechanism involved in this function. These data suggest that rIFN-gamma and LPS, likely through a proinflammatory network, up-regulate the release of IL-beta, IL-6 and TNF-alpha, which could trigger antimicrobial activity against A. castellanii infection in the brain.

Endogenous amoebic endophthalmitis

A 42-year-old man experienced abrupt reduction of vision in the left eye and had vitreous opacity and hypopyon on initial examination. He underwent an emergency vitrectomy and phacoemulsification with posterior capsulectomy, followed by a 2-week course of intravenous fluconazole and antibiotics. The final visual acuity was 20/20 OS. Amoebas, together with polymorphonuclear cells, were observed on examination of specimens of the aqueous humor and vitreous fluid obtained during the surgery. Staphylococcus epidermidis was also cultured from the vitreous fluid. The amoebas had a crescent-shaped periphery of the cytoplasm and ambiguous nuclei. Ultrastructurally, the cytoplasm was surrounded by a thick electron-dense coating. The early vitrectomy and combined use of antibiotics and antifungals might have led to the good visual outcome in this patient.

Tropical infection and the lung

The term "tropical lung" has been used to describe the lungs that are vulnerable to those indigenous diseases that occur with particular prevalence in tropical countries. International travel, student and cultural exchanges and changing immigration patterns are insidiously transforming the face of medicine in Europe and other developed countries. The climates of tropical countries provide an ideal environment for pathogenic organisms, and their vectors and intermediate hosts, to flourish. In an average out-patient department, 20-40% of patients have been seen with respiratory complaints, and 20-30% of hospital medical admissions are for disorders predominantly affecting the lungs. Pulmonary tuberculosis is common in tropical countries as well as the rest of the world. The other principal environmentally related tropical pulmonary diseases are melioidosis, paragonimiasis, amoebiasis, leptospirosis, gnathostomiasis and tropical eosinophilia. It is essential that the practising clinician be aware of the increasing prevalence of various new and exotic tropical lung diseases. Clinicians in developing countries can now use their clinical skills together with recent developments in immunology, molecular biology and biochemistry to improve the diagnostic accuracy and therapeutic effectiveness related to tropical lung infections. Treatment, if inappropriate, may not only be worthless but, in many cases, extremely harmful and even fatal.

Acanthamoeba keratitis, clinico-pathological report of 2 cases

Acanthamoebae have in the last 14 years been reported to be responsible for severe keratitis in an increasing number of cases. To our knowledge this is the first report of acanthamoeba keratitis (AK) in Scandinavia. Two young males, both wearing soft contact lenses for extended wear, developed long lasting, therapy resistant keratitis. As the keratitis progressed to risk of perforation, keratoplasty was performed on the clinical, and in the one case biopsy-proven diagnosis of AK. Histopathology on the removed discs demonstrated the presence of typical acanthamoebae in the corneal stroma. The observation period after keratoplasty is at present 5 and 20 months, respectively. Both grafts have remained clear and visual acuity is 6/9-6/12 with glasses.

Susceptibility of Acanthamoeba to cryotherapeutic method

Acanthamoeba keratitis is becoming an increasingly well-known clinical entity. The Acanthamoeba species in their encysted state are resistant to antimicrobial agents, resulting in corneal infections that are refractory to medical therapy. Corneal cryotherapy has been used to treat Acanthamoeba keratitis with varying and equivocal success. We subjected trophozoites and cysts of two species of Acanthamoeba recovered from corneal infections to trials of in vitro freeze-thaw-refreeze cryotherapeutic methods. The trophozoites of both species were killed in all trials. However, the cysts of both species survived all trials. Cryotherapy may not be an effective means to eliminate Acanthamoeba cysts from the cornea.

Concomitant and secondary bacterial infection of the pus in hepatic amoebiasis

In a series of 48 consecutive patients with clinically diagnosed uncomplicated amoebic liver abscess (ALA), the pus obtained by closed drainage of the abscess was bacteriologically sterile. Secondary bacterial infection of the ALA as a direct result of the aspiration procedure occurred in only 1 patient, the causative organism being Escherichia coli. Entamoeba histolytica was identified in a total of 39 cases (81%) by means of direct microscopy of the pus as well as culture methods.

[Acanthamoebae, Naegleria and other free-living Amoebae in cooling and rinsing water of dental treatment units]

215 water samples were taken from 49 dental treatment units and investigated for the existence of free-living amoebae. In all water-carrying systems of the dental treatment units it was possible to verify the incidence of one or more amoeba species. In 8.2 per cent of the units Naegleria species was found and in 12.2 per cent Acanthamoeba species was present. Seven Naegleria and six Acanthamoeba strains (2 A. castellanii and 4 A. polyphaga) were isolated. From samples originating from 12 dental treatment units (DTU) another 42 amoeba strains were isolated which consisted of 14 different species within 9 classes. Among them Vannella mira (in 19 per cent of samples) and Hartmannella vermiformis (10.6 per cent) were found to be the most frequent species, followed by H. cantabrigensis (9.5 per cent), V. platypodia, Platyamoeba stenopodia and V. simplex (7.1 per cent each). In 10 per cent of samples monotrichous and bitrichous flagellates such as the Bodo species were found, whereas two samples contained ova, larvae and adult free-living nematodes. Among the isolated Naegleria strains no thermophilic strain was present. Consequently they belong to the N. gruberi complex. Among the Acanthamoebae five of the six strains were thermophilic. All strains were investigated for pathogenic properties by means of the mice inoculation test. Two strains proved pathogenic - it was possible to isolate them from the brain and lung of dead mice. Another two strains proved to have invasive properties because they were isolated from the brain of infected animals; however, they did not give rise to disease or death of the respective animals. Supplementary microbiological tests demonstrated the existence of bacteria and fungi in 84 per cent of dental treatment units. Pseudomonas spec. were detected in 75% of dental units, Serratia marcescens in 2% and fungi in nearly 3%. 58.3% of all water samples contained total germ counts of more than 100/ml.

Acanthamoebiasis and immunosuppression. Case report

Immunosuppression and debilitating illnesses are occasionally associated with multifocal brain lesions of Acanthamoebiasis, an encephalitis distinct from the acute, water-sport related meningoencephalitis caused by Naegleria fowler. A 38-year-old man with a renal transplant two and one-half years before his final illness developed pneumonia due to Legionella micdadei. Candida albicans was isolated from sputum and cytomegalovirus was found in lung and liver biopsies. He had continuous corticosteroids, broad spectrum antibiotics, and immunosuppressive therapies. Coma developed and computerized tomography of the head revealed multifocal areas of decreased density, interpreted as cerebral abscesses. Brain biopsy demonstrated encephalitis and amoebae (Acanthamoeba castellanii). Four days after brain biopsy, he died and multifocal hemorrhagic lesions were found in the cerebral hemispheres, brainstem, and cerebellum. This case supports the hypothesis that Acanthamoebiasis is an opportunistic infection.

Subacute and chronic meningoencephalitis in mice after experimental infection with a strain of Naegleria fowleri originally isolated from a patient

Swiss mice were inoculated intranasally with trophozoites of a cloned substrain of the Naegleria fowleri strain LL originally isolated from a human being. The original strain had decreased in virulence after ten years of maintenance in axenic culture. survivors were sacrificed from the fourth to the tenth week p.i. They were tested in a labyrinth experiment in which some demonstrated a diminution in performance. N. fowleri could be reisolated from the brains of five clinically inconspicuous animals. The histopathological findings in the brains of these animals resembled the features of a chronic granulomatous amebic encephalitis (GAE) which has been described in infections due to Acanthamoeba spp. It was not expected that N. fowleri could also produce latent infections. The significance of these findings is discussed.

Adhesion of Entamoeba histolytica trophozoites to monolayers of human cells

The adhesion of radiolabeled trophozoites of Entamoeba histolytica to monolayers of a human intestinal epithelial cell line was found to be dependent on time, temperature, and concentration. Adherence seems to be mediated by a carbohydrate binding protein (lectin), which was previously found in trophozoites of E. histolytica. The adherence of the trophozoites was found to be pH-dependent and was inhibited by several N-acetyl-glucosamine-containing glycoconjugates, such as bacterial peptidoglycan, chitin, and IgA; similar results were obtained with the isolated lectin. Furthermore, the semipurified amoebic lectin and wheat germ agglutinin, which have similar sugar specificities, competed with the intact amoeba for receptor sites on the epithelial cells. In addition, both sera from patients with amoebiasis and an IgG fraction from these sera inhibited lectin activity and the adherence of the trophozoites.

Fulminant amebic meningoencephalitis due to Acanthamoeba

A 57-year-old chronically immunosuppressed woman with systemic lupus erythematosus developed fulminant meningoencephalitis due to Acanthamoeba castellanii. Amebic trophozoites were also found in the lungs, suggesting a primary pulmonary focus of infection. This case illustrates that Acanthamoeba can cause a fulminant, rapidly fatal meningoencephalitis, as well as the previously reported chronic granulomatous meningoencephalitis. X

[Primary amebic meningoencephalitis and the pathogenic potential of limax amoebas]

During the last two decades it has been proved that free amoeba of the Naegleria and Acanthamoeba (Hartmanella) genera, formerly considered as inocuous protozoa, are the etiological agent of a newly described morbid entity: primary amoebic meningoencephalitis. The clinical aspects of this disease, its clinical and laboratory diagnosis, the pathogenic potential of these amoebae, epidemiological data, prophylaxis and treatment, have promoted medical interest in this disease and in the possibility of a differential diagnosis with other meningoencephalitides.

Ultrastructural observations of experimental Naegleria meningoencephalitis in mice: intranuclear inclusions in amebae and host cells

Primary amebic meningoencephalitis was experimentallly produced in mice through intranasal instillation of pathogenic Naegleria fowleri. Experimental animals had a 64% mortality with average time of onset of symtoms of death occurring on the 7-8th day following inoculation. Ultrastructural studies of the olfactory lobes from brains of dead (or sacrificed) animals revealed major concentrations of amebae in the perivascular regions; amebae were also seen to be under attack by host polymorphonuclear leukocytes, and in the lumina of blood vessels. Amebae in brain tissue contained 30 nm intranuclear particles arranged in clusters. In the brains of some mice, dead presumably as a result of amebic meningoencephalitis, particles and crystalloids were observed in the nuclei of degenerating cells of the central nervous system. Some alternatives are examined to explain a possible relationship between ameba intranuclear particles and mouse brain cell intranuclear inclusions.

[Amoebic meningoencephalitis by "Eaegleria" and "Acanthamoeba" (author's transl)]

Primary amoebic meningoencephalitis (ME) by Naegleria fowleri a free-living protozoon found in fresh, warm waters, is a well known fatal disease lasting less than one week. It affects sporadically swimmers and children playing in mud puddles. Less than 100 cases have been described. Recently a more rare, distinct amoebic meningoencephalitis due to some species of free-living Acanthamoeba was identified, lasting some weeks or more but still with a fatal evolution. In this case the amoebae do not always enter the brain directly through the cribrous membranes but cause mild, primary infections of respiratory airways: exceptionally, mainly in immunodepressed subjects, they then reach the CNS causing a secondary ME. Naegleria is fairly sensitive in vitro to some drugs, but in vivo their efficacy is dramtically lowered for pharmacokinetic reasons. Acanthamoeba is in every respect less sensitive. Prophylaxis is almost impossible to achieve. Some diagnostic procedures are described and the importance of their use in diagnosis of the so called aseptic purulent ME is stressed.

Pathogenic amoebas from brackish and ocean sediments, with a description of Acanthamoeba hatchetti, n. sp

Acanthamoeba culbertsoni was isolated from a sewage-spoil dump site near Ambrose Light, New York Bight. A second species, Acanthamoeba hatchetti, n. sp., was isolated from Brewerton Channel, Baltimore Harbor, Maryland. Both species killed laboratory mice after infection by the intranasal route.

Naturally occurring gastric amebiasis in the wallaroo

Gastric amebiasis occurred naturally in two wallaroos in the Baton Rouge Zoo. Infection by an Entamoeba sp. parasite was confined to the forestomach and was characterized by hemorrhage and necrosis of the mucosa; parasitic invasion of the lamina propria, submucosa, and muscularis; and extensive gastric edema. Typical amebic cysts were found in the feces of the animal that died and of those in contact. Gastric amebiasis has not previously been reported in marsupials.