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PubMed1982

[The Status Of Intestinal Protozoan Infections In Inhabitants Of Gangweon-Do, Korea]

To evaluate the status of intestinal protozoan infections in inhabitants of Gangweon-Do, Korea, a total of 1,310 stool specimens (male 669, female 641) was collected from 2 cities and 3 counties. They were examined routinely 1 time by the method of formalin-ether sedimentation technique. The results were as follows: 1. The positive rate for any kind of the intestinal protozoan cysts was 8.9 %. 2. A total of 6 kinds of the intestinal protozoan cysts were detected. The prevalence rate of each protozoa were; E. histolytica 0.8 %, E. coli 7.6 %, E. nana 1.4 %, I. butschlii 0.2 %, G. lamblia 0.5 % and C. mesnili 0.5 %. 3. Sogcho-city showed the highest positive rate as 15.2 %, Myeongju county was the next as 11.3 % and Weonju-city showed the lowest positive rate as low as 3.9 %. 4. By age, the highest positive rate was found in 20-29 age group(12.4 %). Female (9.5 %) showed a slight higher positive rate than male (8.4 %).

Journal Article↗
PubMed1977

The effect of chronic protozoan infection by Babesia rodhaini on leukemogenesis in mice.

The effect of chronic infection with the protozoan parasite Babesia rodhaini on the subsequent development of mouse leukemia was investigated in three different murine leukemia-lymphoma model systems: congenital lymphoma (in AKR mice), irradiation-induced lymphoma (in C57BL mice), and Rauscher-virus-induced leukemia in NMRI mice. Leukemia incidence was significantly greater than in controls in Babesia-infected (NMRI strain) mice that had been infected with an adjusted dose of Rauscher leukemia virus.

Animals↗
PubMed2005

Risk of intestinal helminth and protozoan infection in a refugee population.

With continuing emigration from endemic countries, screening for parasitic infections remains a priority in U.S. communities serving refugee and immigrant populations. We report the prevalence of helminths and protozoa as well as demographic risk factors associated with these infections among 533 refugees seen at the Santa Clara County, California, Refugee Clinic between October 2001 and January 2004. Stool parasites were identified from 14% of refugees, including 9% found to have one or more protozoa and 6% found to have at least one helminth. Most common protozoan infections were Giardia lamblia (6%) and Dientamoeba fragilis (3%), and for helminths, hookworm (2%). Protozoa were more frequent in refugees < 18 years of age (OR: 2.2 [1.2-4.2]), whereas helminths were more common in refugees from South Central Asia (OR: 8.0 [2.3-27.7]) and Africa (OR: 5.9 [1.6-21.6]) when compared with refugees from Eastern Europe and the Middle East. Among helminths, Ascaris lumbricoides and hookworm were concentrated among South Central Asians (6 of 7 and 10 of 11 cases, respectively), whereas Strongyloides stercoralis was predominantly found in Africans (5 of 7 cases). Although predeparture empirical treatment programs in Saharan Africa may have helped to reduce prevalence among arriving refugees from this region, parasitic infection is still common among refugees to the United States with helminth infections found in more specific populations. As refugees represent only a fraction of recent immigrants from endemic countries, current studies in nonrefugee groups are also needed.

Adolescent↗
PubMed1998

Gap junction disappearance in astrocytes and leptomeningeal cells as a consequence of protozoan infection.

Trypanosoma cruzi and Toxoplasma gondii are protozoan parasites capable of causing infections of the nervous system. In order to determine effects of infection by these organisms on intercellular communication in the brain, dye coupling and connexin abundance and distribution were examined in leptomeningeal cells and astrocytes infected with T. cruzi or T. gondii. For both cell types infected with either type of protozoan parasite, intercellular diffusion of intracellularly injected Lucifer Yellow was dramatically reduced. Immunocytochemistry with antibodies specific for connexin43 (in astrocytes) or both connexin43 and connexin26 (for leptomeningeal cells) demonstrated that punctate gap junctional staining was much reduced in infected cells, although uninfected neighbors could display normal connexin abundance and distribution. Western blot analyses revealed that connexin43 abundance in both cell types infected with either parasite was similar to that in uninfected cells. Phosphorylation state of connexin43 (inferred from electrophoretic mobility of connexin43 isoforms) was not significantly affected by the infection process. Immunocytochemistry of whole brains from animals acutely infected with either parasite also showed a marked reduction in connexin43 expression. We conclude that infection of both types of brain cells with either protozoan parasite results in a loss of intercellular communication and organized gap junction plaques without affecting expression levels or posttranslational processing of gap junction proteins. Presumably, these changes in gap junction distribution result from altered targeting of the junctional protein to the plasma membrane, and/or from changes in assembly of subunits into functional channels.

Animals↗
PubMedDate not supplied

[Characteristics of the immune response in protozoan infections].

INTRODUCTION: When protozoa enter the blood stream or tissues they can often survive and replicate because they adapt to the resisting natural host defenses. The interaction of immune system with infectious organisms is a dynamic interplay of host mechanisms aimed at eliminating infections and microbial strategies designed to permit survival in the face of powerful effector mechanisms. Protozoa cause chronic and persistent infections, because natural immunity against them is weak and because protozoa have evolved multiple mechanisms for evading and resisting specific immunity. NATURAL AND SPECIFIC IMMUNE RESPONSE TO PROTOZOA: Different protozoa vary greatly in their structural and biochemical properties and stimulate distinct patterns of immune responses and have evolved unique mechanisms for evading specific immunity. Protozoa activate quite distinct specific immune responses, which are different from the responses to fungi, bacteria and viruses. Protozoa may be phagocytozed by macrophages, but many are resistant to phagocytic killing and may even replicate within macrophages. T. brucei gambiense is the best example of protozoa which can induce humoral immune response because of its extra-cellular location. In Leishmania sp. infections, cellular defense mechanisms depend upon CD4+ T-lymphocytes and activate macrophages as effector cells that are regulated by cytokines of Th1 subset. Plasmodium sp. is a protozoa which show the diversity of defence mechanisms which can be cellular or humoral, depending on Ag and protozoa's location. IMMUNE EVASION MECHANISMS OF PROTOZOA: Different protozoa have developed remarkably effective ways of resisting specific immunity: a) anatomic sequestration is commonly observed with protozoa Plasmodium and T. gondii; b) some protozoa can become resistant to immune effector mechanisms: Trypanosoma, Leishmania and T. gondii; c) some protozoa have developed effective mechanisms for varying their surface antigens: Plasmodium and Trypanosoma; d) some protozoa shed their antigen coats, either spontaneously or after binding with specific antibodies: E. histolytica; e) some protozoa alter host immune response by nonspecific and generalized immunosuppression (abnormalities in cytokine production, deficient T cell activation): Trypanosoma, Leishmania, Toxoplasma, Entamoeba. CONCLUSION: Protozoa activate numerous, different immune mechanisms in human body. Evolution, progression and outcome of diseases depend upon these mechanisms. Resent progresses in research have defined and selected Ag as candidates for new vaccines. Better definitions regarding the role of cytokines in protozoan infections will facilitate rational development of cytokines and cytokine antagonists and their use as immunotherapeutic agents.

Animals↗
PubMed1996

Intracellular protozoan infection in small intestinal biopsies of patients with AIDS. Light and electron microscopic evaluation.

Small intestinal biopsies of 21 patients with acquired immunodeficiency syndrome (AIDS) with light microscopic findings diagnostic or suspicious for parasite infection were investigated by transmission electron microscopy (TEM). TEM allowed us to identify and specify the genus and species of involved parasites in 16 out of the 21 cases: 7 Cryptosporidium parvum, 5 Enterocytozoon bieneusi and 4 Isospora belli. Cryptosporidium was easily identified on light microscopy (LM), and only slightly influenced by parasite burden in all the 7 cases; TEM confirmed LM diagnosis and made it possible to characterize the parasites as C. parvum. The identification of Microsporidium on LM in our cases was related to the burden of parasite; its presence was certainty identified in 2 cases and suspected in 3. TEM allowed to identify these parasites as E. bieneusi. Intracytoplasmic coccidia could be detected with certainly in semithin sections in all 4 cases, but TEM was always needed to specify the infectious agent as I. belli. In 5 cases the suspicious of protozoan infection on LM (3 microsporidia, 1 intracytoplasmic coccidia and 1 Cryptosporidium) was not confirmed by TEM. Our data suggest that TEM is an appropriate diagnostic tool in this field of pathology and necessary in most of the cases.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Neospora-like protozoan infection as a major cause of abortion in California dairy cattle.

Ninety-five aborted bovine fetuses received from California dairies over a 4.5-year period had histologic lesions of focal encephalitis. Protozoa that reacted with Neospora caninum antiserum were detected in the brain of 88 of these fetuses and in the heart of 1 fetus. Sarcocystis spp schizonts were seen in the vascular endothelium of 1 fetus. It was concluded that a Neospora-like cyst-forming coccidian may be a major cause of abortion in California dairy cattle.

Abortion, Veterinary↗