Giardiasis, Isosporiasis and Balantidiasis

Phylogenetics and Pathogenicity of Balantioides coli Isolates in Vietnamese Weaned Pigs

PURPOSE

This study aimed to investigate the diversity of Balantioides coli (B. coli) based on the 18S rDNA of isolates collected from weaned pigs with diarrhea and then select a B. coli isolate to determine its pathogenicity in weaned pigs through experimental infection.

METHODS

The genetic analysis of field-isolated B. coli strains was based on sequencing of the partial 18S rDNA genetic fragment and the pathogenicity of an isolate of B. coli (DN2018-2-DTD) was identified through an experimental infection.

RESULTS

The fourteen B. coli isolates shared 98.47-100% nucleotide similarity and were divided into two clades in a phylogenetic tree. In an infection experiment, a slight increase in the body temperature was identified in two infected groups as compared to that in the control group (P < 0.05) from days post-infection (dpi) 12-18 and from dpi 20-27. In the group infected with 3000 CPG/TPG, 2/9 pigs started to develop diarrhea on day two. In the group infected with 500 CPG/TPG, 8/9 pigs had diarrhea on dpi 3. Trophozoites/cysts of B. coli were firstly detected in feces on dpi 3 in a group of pigs infected with a dose of 3000 CPG/TPG, and CPG/TPG reached its peak at dpi 5 in both groups of infected pigs (35,450 and 13,250 CPG/TPG). There was a significant difference in the bodyweight of the control group (noninfected) as compared to that of the groups of infected pigs on dpi 7 (P < 0.05), 14 (P < 0.001) and 28 (P < 0.01). Lesions were solely recorded in infected pigs, including white ulcerative nodules with necrosis scattered in the mucosa of the colon and cecum on dpi 7, 14, and 28.

CONCLUSION

This is the first study to investigate the pathogenicity of B. coli in Vietnamese pigs to demonstrate that B. coli could induce necrotic ulcerative enteritis and diarrhea in weaned pigs.

Balantidiasis in the gastric lymph nodes of Barbary sheep (Ammotragus lervia): an incidental finding

A 4-year-old female Barbary sheep (Ammotragus lervia) was found dead in the Gwangju Uchi Park Zoo. The animal had previously exhibited weakness and lethargy, but no signs of diarrhea. The carcass was emaciated upon presentation. The main gross lesion was characterized by severe serous atrophy of the fat tissues of the coronary and left ventricular grooves, resulting in the transformation of the fat to a gelatinous material. The rumen was fully distended with food, while the abomasum evidenced mucosal corrugation with slight congestion. Microscopic examination revealed the presence of Balantidium coli trophozoites within the lymphatic ducts of the gastric lymph node and the abdominal submucosa. On rare occasions, these organisms may invade extra-intestinal organs, in this case the gastric lymph nodes and abomasum.

Pulmonary Balantidium coli infection in a leukemic patient

A 59-year-old woman suffering from chronic lymphocytic leukemia developed pulmonary lesions; bronchoalveolar lavage was performed for possible systemic fungal infection. However, direct microscopic analysis revealed ciliated protozoa identified as Balantidium coli. B. coli is the only known pathogenic ciliate, and is usually associated with intestinal infection in areas associated with pig rearing. On very rare occasions the organisms may invade extra-intestinal organs, in this case the lungs of an immunocompromised patient. This case is unusual as balantidiasis is rare in Europe, the patient had no obvious contact with pigs, and there was no history of diarrhea prior to pulmonary colonization. Metronidazole was rapidly administered, and the condition improved after 24-48 hr.

Balantidium coli pneumonia in an immunocompromised patient

A fatal case is reported of Balantidium coli pneumonia in a 71-y-old woman suffering from anal cancer. The diagnosis was made by the discovery of motile trophozoites in a wet mount from bronchial secretions. The usual habitat of the parasite is the colon; lung balantidiasis is very rare.

Colonoscopy in inflammatory bowel disease

This article discusses the important role endoscopy plays in the diagnosis and management of inflammatory bowel disease and how the procedure adds crucial information to the constellation of history, physical examination, radiographic findings, and laboratory values. Differentiation between Crohn's disease and ulcerative colitis has important ramifications for medical therapy, surgical options, and prognosis. This distinction can be accurately made in at least 85% of patients.

Crohn's disease is frequently complicated by giardiasis

Giardiasis is a common infection, and many of its symptoms are similar to those of Crohn's disease. Despite a long discussion on the role of microbiologic agents in Crohn's disease, giardiasis has never been investigated. We studied giardiasis as assessed by the occurrence of cysts in 86 patients with Crohn's disease, in 82 patients with other gastrointestinal disease, and in 52 patients without gastrointestinal disease. In addition, in 20 patients with Crohn's disease the effects of metronidazole on giardiasis and disease activity were studied. Frequency of giardiasis was 61.6% in patients with Crohn's disease, 31.7% in patients with other gastrointestinal disease, and 5.8% in the control group (p less than 0.01). Stool frequency, disease activity, and humoral signs of inflammation in patients with Crohn's disease showed no relationship to giardiasis. All but two patients treated with metronidazole became free of cysts. Crohn's disease activity index decreased in 14 of 20 patients (p less than 0.05). In conclusion, giardiasis is a common finding in patients with Crohn's disease. Treatment of giardiasis can, in individual cases of Crohn's disease, result in a quick recovery from symptoms of high disease activity.

Protozoal infections in the acquired immunodeficiency syndrome

Several protozoa have emerged as the major opportunistic infections and cause of death in patients with acquired immunodeficiency syndrome (AIDS). Pneumocystis carinii pneumonia is the leading cause of death in AIDS patients. Electron microscopy (EM) usually shows numerous trophozoites and cysts of Pneumocystis filling up the entire alveolar space, while only cysts are seen under the light microscope. The focal thickening of cyst wall of Pneumocystis, as demonstrated by EM and manifested as a "parentheses" shaped structure with silver stain, serves as a diagnostic marker for Pneumocystis. Freeze-fracture EM has demonstrated the intimate contact between Pneumocystis trophozoites and the type I pneumocytes, which may contribute to the alveolar-capillary block, leading to severe respiratory distress. However, EM is seldom needed for the diagnosis of this infection. Toxoplasma encephalitis, which is an unusual clinical manifestation in cases of toxoplasmosis reported previously, has become a common complication and one of the major causes of death in patients with AIDS. Because subclinical infection by Toxoplasma is common, serologic tests usually offer no definite answers as to whether the infection is acute or chronic, active or past. The small size and its non-specificity in both morphology and tissue affinity make light microscopic diagnosis of toxoplasmosis difficult. Only immunologic staining, such as immunoperoxidase and immunofluorescence, can help to achieve a definite positive identification of the organism. When special antibodies or facility for such staining is not available, EM is the final resort for identifying Toxoplasma by showing the apical complex with the characteristic sausage-shaped rhoptries. Cryptosporidiosis, practically unknown before the AIDS outbreak, has become one of the most common intestinal protozoa in both immunocompromised and immunocompetent patients. The protracted and sometimes fatal course of cryptosporidiosis in immunocompromised patients can be explained by the presence of autoinfective oocysts (thin-walled oocysts), as detected by EM, and by recycling of first-generation schizonts observed experimentally. While diagnosis of cryptosporidiosis can be made by detection of oocysts in stools in most cases, EM is still the last resort for a definitive identification of Cryptosporidium species. While the incidence of isosporiasis is still low, it has been found more frequently in patients with AIDS than in the general population. The parasite, Isospora belli, being a coccidian as is the Cryptosporidium species, is similar to the latter in its life cycle and clinical manifestations.(ABSTRACT TRUNCATED AT 400 WORDS)

Gastrointestinal zoonoses

Infectious gastrointestinal diseases affect man and animals throughout the world. Certain etiologic agents (for example, Salmonella spp., Campylobacter jejuni, Yersinia enterocolitica, Cryptosporidia, Strongyloides stercoralis, Echinococcus granulosa) seem to have the potential to be transmitted from pets to people, causing severe disease in the latter. Other agents seem unlikely to be transmitted but may have the potential to be zoonoses. This article discusses proved, suspected, and possible zoonotic agents that may originate from the gastrointestinal tract of dogs and cats.

An eight-year study of the viral agents of acute gastroenteritis in humans: ultrastructural observations and seasonal distribution with a major emphasis on coronavirus-like particles

During an 8-yr period, 862 stool specimens from patients with gastroenteritis were examined by electron microscopy after negative staining with 2% phosphotungstic acid (pH 6.5). Forty-one percent of the specimens submitted over an 8-yr period were determined to be positive for virus or viruslike particles belonging to one or more of seven morphologically distinct viral groups. Coronavirus-like particles (CVLPs) were present in 69.8% of the positive stool specimens. Membranous profiles containing "complement-type" holes (10 nm in diameter) were identified in some preparations containing CVLPs. The second most prevalent viral agent found in stool specimens was the rotavirus (17% of all positive stools). The incidence of other viruses identified in the survey were as follows: adenovirus 4.5%, picorna/parvovirus agents 2.9%, Norwalk-like agent 2.9%, astrovirus 1.9%, and calicivirus 0.5%. Unclassified small round viruses (approximately 25-30 nm in diameter) represented 0.5%. It was also determined that there was a seasonal distribution in excretion of all viruses except for CVLPs. A greater number of viruses were identified in the cooler, drier months of the year.

Post-infective malabsorption in the temperate zone

A series of 37 adults normally resident in Britain have been investigated for persistent bowel symptoms following acute enteritis. 26 had intestinal malabsorption, of whom 12 had been travelling in the Mediterranean area, whereas 10 developed their illness at home. Mild jejunal mucosal abnormalities were found in cases with and without malabsorption, and the intraepithelial lymphocyte count correlated more closely with the degree of malabsorption than did the histological grading. Over 80% of severe cases were folate deficient. Enterobacteria were cultured from the jejunal fluid in 30% of cases. Our observations confirm that post-infective malabsorption occurs sporadically in adults in the temperate zone and is occasionally severe. The condition involves small bowel contamination with enterobacteria, and it differs from acute tropical sprue only in its greater tendency to spontaneous recovery.

Immunodiagnosis of giardiasis by ELISA and studies on cross-reactivity between the anti-Giardia lamblia antibodies and some heterologous parasitic antigens and fractions

Specific antibodies against Giardia lamblia in 92 sera from asymptomatic carriers were investigated by ELISA. Using cyst antigen, antibodies were detected in 91 of the sera, by means of alkaline phosphatase-labelled antispecies immunoglobulin. The E/405nm values of the positive sera ranged between 0.350 and 1.700, whereas in the 78 control sera they were 0.270 +/- 0.220. Cross-reactivity between the anti-G. lamblia antibodies and 18 heterologous parasitic antigens and fractions was also studied. Cross-reactions were observed with antigens of Toxoplasma gondii, Sarcocystis spp., Leishmania donovani, Fasciola hepatica Y, F. hepatica I, Echinococcus granulosus AM, Cysticercus tenuicollis, Taenia saginata, Dipylidium caninum Y, D. caninum I, Trichuris suis Y, T. suis I, Trichinella spiralis and Litomosoides carinii. No cross-reactions were observed with the antigens and fractions of Entamoeba histolytica, Dicrocoelium dendriticum, Schistosoma mansoni and Echinococcus granulosus Y. The results show that the ELISA could be easily and very successfully applied for routine diagnosis of giardiasis.

Parasitic bowel disease: three pathogens important in primary care

A high index of suspicion and careful application of diagnostic methods are essential for accurate diagnosis of parasitic bowel diseases. The varied clinical spectrum of giardiasis, amebiasis, and strongyloidiasis emphasizes the need to consider these pathogens when patients present with gastrointestinal complaints. Giardiasis should be suspected in patients, especially returned travelers, with unexplained increase in stool frequency, particularly with bloating, flatulence, or vague systemic symptoms. Amebiasis must be considered in the differential diagnosis of any patient who presents with persistent diarrhea or signs of inflammatory bowel disease. Unexplained diarrheal illnesses associated with upper abdominal symptoms and eosinophilia should raise suspicion of the presence of strongyloidiasis. These findings in a patient with a compromised immune system or in a candidate for immunosuppressive therapy should prompt a thorough investigation to rule out this parasite, since disseminated strongyloidiasis often is fatal.

Chronic malabsorption due to cryptosporidiosis in a child with immunoglobulin deficiency

A case of fatal cryptosporidiosis in a child with primary immunoglobulin deficiency is described. This is always a serious complication in immunodeficient patients because there is no known effective therapy.

Giardiosis and colitis in a dog

An 18-month-old Cavalier King Charles Spaniel with recurrent diarrhoea for 2 months had signs suggesting dysfunction of small and large bowel. No helminth ova, protozoa or fat were found on faecal examination. Proctoscopy, barium enema examination and colonic biopsy revealed mucosal colitis. Biopsied small intestine was histologically normal but Giardia trophozoites were numerous in fluid aspirated from the duodenum. Absorption of d-xylose was normal. Giardiosis and idiopathic colitis were diagnosed. Clinical signs abated after 2 courses of metronidazole administration.