Variable infectivity of human-derived Giardia lamblia cysts for Mongolian gerbils (Meriones unguiculatus).

To determine whether gerbils can be used as a suitable animal model for giardiasis, we attempted to infect Mongolian gerbils with cysts of Giardia lamblia isolated from the stools of 10 humans with symptomatic and asymptomatic giardiasis. We obtained 100% infection with one isolate (CDC:0284:1), as evidenced by the presence of numerous trophozoites in the intestines of the gerbil and cysts in the feces. Cysts from four patients were not infective, while cysts from the other five patients produced infections in 11 to 75% of the animals. On the basis of these and other experiments, we concluded that (i) only certain isolates of human G. lamblia infect gerbils, colonize the intestine, and complete their life cycle by undergoing differentiation into cysts; (ii) the infection could last for about 39 days, but the animals excreted maximum numbers of cysts on about day 13 postinfection; (iii) the pattern of cyst excretion was irregular, and some gerbils, like humans, excreted cysts intermittently; (iv) the minimum number of cysts needed to establish an infection in 50% of the gerbils was 100; and (v) only certain strains retained the ability to infect gerbils even after repeated animal passage.

Isoenzyme analysis of Babesia microti infections in humans.

We used high-resolution polyacrylamide gradient gel electrophoresis (PGGE) to separate four babesial enzymes to aid in the identification of two Babesia microti isolates established in hamsters. The isolates were compared to two different hamsters passages of the "Gray" strain. All isoenzymes patterns from the two isolates and the "Gray" strain were similar except glucose phosphate isomerase (GPI) from one of the "Gray" strain passages. It showed a polymorphic GPI pattern as opposed to a monomorphic GPI pattern seen in the other "Gray" strain passage and the two isolates. The observed differences suggested that some population of B. microti are capable of having polymorphic GPI, that the "Gray" strain originally contained (and may still contain) a heterogeneous population of B. microti, and that the population possessing polymorphic GPI was selected over that with monomorphic GPI. This information was obtained by a PGGE method that eliminated hemoglobin from gels and allowed, for the first time, detection of babesial leucine amino peptidase (LAP) and isocitrate dehydrogenase (IDH). In addition, this method provided molecular weight estimations on babesial GPI, LAP, IDH, and glutamate dehydrogenase (GDH), and it proved useful in the identification and characterization of the B. microti isolates.

Immunologic tools in the diagnosis of amebiasis: epidemiology in the United States.

Several immunodiagnostic tests that detect antibody to Entamoeba histolytica are now available. Such tests are useful when demonstration of the etiologic agent is difficult (as in liver abscess), when routine diagnostic tests fail to disclose the organisms (as in severe intestinal disease compromised by failure of the laboratory to identify the organism or by the patient's use of interfering substances), and as epidemiologic tools for determining the prevalence of invasive disease in populations. Knowledge of the prevalence of amebiasis in the United States is incomplete because the disease is not routinely reported. Information currently available on the prevalence of amebiasis has accumulated from studies of selected groups that include children, institutionalized persons, members of extended families, immigrants, and male homosexuals.

Respiratory epithelial cells masquerading as agents of primary amebic meningoencephalitis: distinguishing features.

CSF does not normally contain motile cells within flagella or cilia. When motile cells are seen in the CSF, they may be incorrectly assumed to be amebae. We studied a patient with a traumatic mucocele, in whom motile ciliated respiratory epithelial cells were seen in the CSF and within a frontal lobe brain abscess.

Hepatocellular carcinoma simulating amebic liver abscess: report of a case and analysis of current diagnostic methods.

Radiological and serological tests are valuable tools commonly used in diagnosing amebic liver abscess. The limitations in sensitivity and specificity of the various imaging procedures should be recognized in order to avoid misinterpretation of test results. Serodiagnostic methods present potential pitfalls primarily because of their frequent inability to differentiate previous disease from active infection, and must therefore be interpreted carefully.

Ophthalmomyiasis interna causing visual loss.

Ophthalmomyiasis interna caused severe intraocular inflammation and loss of vision in two eyes. In the first eye, the organism was found in the vitreous and created a severe uveitis; a second-stage larva of Hypoderma lineatum was later removed from the anterior chamber. Phthisis bulbi ensued with loss of all vision. In a second eye, a subretinal maggot was observed to produce tracks in the pigment epithelium, with subretinal and vitreous hemorrhage. Severe uveitis and traction retinal detachment later developed. Despite successful reattachment of the retina, visual acuity remained only light perception. These cases demonstrate that ophthalmomyiasis interna is not always a benign condition.

Serologic and parasitologic studies of amebiasis in two suburban communities of Maracaibo, Venezuela.

Se realizaron estudios serologicos y parasitologicos de amibiasis en dos comunidades suburbanas de bajas condiciones socioeconomicas de Maracaibo, Venezuela. Se obtuvieron muestras de sueros, las cuales se examinaron con la tecnica de hemaglutinacion indirecta y especimenes fecales que se estudiaron mediante frotis fecales tenidos con hematoxilina ferrica y concentrados segun el metodo del formol-eter.Las tasas de seropositividad obtenidas fueron de 12.1 y 29.2%, presentando titulos bajos la mayoria de los sueros positivos.El porcentaje de seropositividad aumento con la edad. Los examenes coprologicos revelaron tasas de infeccion con Entamoeba histolytica de 2.6 y 7.3%. Los resultados presentes indican que la importancia de la amibiasis en nuestra region varia de una comunidad a otra, dependiendo de los diversos factores asociados con cada una de ellas

Isolation of Trichomonas vaginalis from the respiratory tract of infants with respiratory disease.

Trichomonas vaginalis was isolated from the respiratory tracts of two infants with respiratory disease. Bacterial and viral cultures of tracheal aspirates and nasopharyngeal specimens did not detect bacterial pathogens or viruses; however, T vaginalis was found to be present in inoculated cell cultures. Both infants were delivered vaginally by mothers with known previous episodes of T vaginalis infection. The possibility that this organism may, on occasion, cause respiratory tract disease needs further evaluation.

Polyacrylamide gel electrophoresis of isoenzymes from Entamoeba species.

In this preliminary report, we describe a polyacrylamide gel electrophoresis technique for the resolution of isoenzyme patterns of four isolates of Entamoeba histolytica and one isolate of Entamoeba coli. Our findings were similar to previous findings for three enzyme systems: maleic enzyme (malate dehydrogenase [EC 1.1.1.40]), hexokinase (EC 2.7.1.1), and phosphoglucomutase (EC 2.7.5.1). We found preliminary evidence that glucosephosphate isomerase (EC 5.3.1.9) may also differentiate invasive amoebae from noninvasive amoebae, when the isoenzymes are separated by polyacrylamide gel electrophoresis, whereas this differentiation is not evident with starch-gel electrophoresis. We used an Rf system to relate isoenzyme band mobility to the migration distance of a standard E. histolytica strain (HK-9). The numerical identification of isoenzyme bands can simplify the grouping of isolates into zymodemes.

Evaluation of two serological tests for Trichomonas vaginalis infection.

Trichomonas vaginalis is a widely prevalent, sexually transmitted protozoan infecting both males and females. Despite its prevalence, little is known about its contribution to the morbidity rates for urogenital-tract infections. Currently accepted diagnostic methods are limited to the demonstration of the organism in fresh material, identification in stained material, or in vitro cultivation of organisms from the urogenital tract. We have evaluated the indirect hemagglutination test and the gel diffusion test for efficacy in detecting antibodies in serum samples drawn from two population groups. Sera from patients attending a vaginitis clinic had a seropositivity rate of 69% by indirect hemagglutination and 34% by gel diffusion. Seropositivity rates among culture-positive patients were 78% with indirect hemagglutination and 43% with gel diffusion. A group of normal female hospital employees showed seropositivity rates of 30% by indirect hemagglutination and 3% by gel diffusion. Absorption of reactive sera with Trichomonas antigens reduced or abolished the serological reactivity, confirming the specificity of the test. Serological methods can provide a rapid, sensitive, and economical tool to study the epidemiology of this common protozoan infection.

An outbreak of amebiasis spread by colonic irrigation at a chiropractic clinic.

From June 1978 through December 1980, at least 36 cases of amebiasis occurred in persons who had had colonic-irrigation therapy at a chiropractic clinic in western Colorado. Of 10 persons who required colectomy, six did. Of 176 persons who had been to the clinic in the last four months of 1980, 80 had received other forms of treatment. Twenty-one per cent of the colonic-irrigation group had bloody diarrhea, as compared with 1 per cent of the non-irrigation group (P = 0.00013). Thirty-seven per cent of the colonic-irrigation group who submitted specimens had evidence of amebic infection on either stool examination or serum titer, as compared with 2.4 per cent in the non-irrigation group (P = 0.00012). Persons who were given colonic irrigation immediately after a person with bloody diarrhea received it were at the highest risk for the development of amebiasis. Tests of the colonic-irrigation machine after routine cleaning showed heavy contamination with fecal coliform bacteria. The severity of disease in this outbreak may have been related to the route of inoculation.

Successful chemotherapy of transfusion babesiosis.

We describe babesiosis transmitted by transfusion. The infected blood donor was identified and a minimum period of infectivity of the donor's blood was established. We report a new modality for chemotherapy consisting of quinine plus clindamycin, and a new endemic focus for this zoonosis on Fire Island, New York. There are insufficient data to establish a reasonably safe period after which visitors and residents of Babesia-endemic foci can become blood donors. Screening of such persons by a rapid serologic test, such as the ELISA or immunofluorescent antibody tests, is suggested.

Epidemiology of human babesiosis on Nantucket Island.

Between 1969 and 1977, 14 persons with parasitologically confirmed Babesia microti infections and seven persons with antibody titers to B. microti greater than or equal to 1:1,024 were identified on Nantucket Island, Massachusetts. Nineteen of these 21 persons were interviewed. About half were permanent residents of Nantucket; the others spent most of their summers on the island. There were 12 women and seven men. Patients ranged in age from 23 to 86 years; all of those with parasitologically confirmed infections were at least 49 years old. Fifteen patients had illnesses characterized by fever, chills, myalgia and fatigue. Five reported being bitten by a tick from 7 to 28 days before the onset of illness. Most cases occurred during July or August. There appeared to be no association between B. microti infection and direct contact with wild or domestic animals or specific outdoor activities. The unusual age distribution of patients with parasitologically confirmed B. microti infections may result because older persons tend to have more severe illnesses and thus are more likely to come to medical attention.

Development and persistence of antibody in persons infected with Babesia microti.

An indirect immunofluorescent test was used to determine antibody titers to Babesia microti in serum samples collected from 16 patients between 1 week and 1 year after the onset of illness. Titers rose to greater than or equal to 1:1,024 during the first few weeks of illness and then fell gradually to 1:16 to 1:256 over the next 5-6 months.