Seasonal trends of Cyclospora cayetanensis infections in a community of Falcon State, Northwestern Venezuela.

BACKGROUND: Cyclosporiasis has a marked seasonality. Few community-based studies have addressed this issue and there are no reports from Venezuela. A study was conducted to determine the seasonal variation of infection in a community from Falcon State, Venezuela. METHODS: A sample of 732 individuals was collected for 1 y. Stools were examined with modified Ziehl-Neelsen carbolfuchsin staining of ethyl acetate-formalin concentrates and ultraviolet epiflorescence of wet mounts. RESULTS: Cyclospora prevalence was 9.9% (73/732) with monthly variation from 0% to 35.3%. A trend of increased infections coinciding with the rainy time was observed (p<0.001). CONCLUSIONS: Cyclosporiasis is common in this area with high endemicity during the rainy periods.

Successful treatment of human Entamoeba polecki infection with metronidazole.

A 24-year-old woman with Entamoeba polecki infection was succesfully treated with metronidazole in a dosage of 750 mg orally thrice daily for 5 days. Examination of two direct smears and two formalin-ether concentrates from specimens collected at 2 days, 1 week, 1 month, and 2 months after the conclusion of therapy revealed no amebae. An indirect hemagglutination test for antibodies to E. histolytica gave a low positive titer of 1:128.

Intestinal parasitic infections, with a special emphasis on cryptosporidiosis, in Amerindians from western Venezuela.

The prevalences of intestinal parasites and intensities of helminth infections were studied in two Amerindian villages in Venezuela. Single stool specimens were collected from 303 individuals from Saimadoyi and 130 from Campo Rosario. Wet mounts, iron-hematoxylin-stained smears, and formalin-ether concentrates were examined for the presence of parasites; modified Ziehl-Neelsen carbol-fuchsin staining of 10% formalin-preserved stool was used to identify Cryptosporidium parvum. Helminth ova counts were made using the standard smear egg count technique. Mixed infections (Campo Rosario = 69.9%, Saimadoyi = 71.6%) were frequent. Overall infection rates with one or more species (Campo Rosario = 79.2%, Saimadoyi = 95.4%; P < 0.01) and with any protozoans (Campo Rosario = 60.8%, Saimadoyi = 72.3%; P < 0.05) were high and predominant (P < 0.05) in Saimadoyi. Cryptosporidiosis was identified in 38 subjects (8.8%) in both villages; 60.6% were asymptomatic carriers. The mean egg counts of helminths were heavier in Campo Rosario (P < 0.05), which was probably due to the drastic reduction of their lands along with their low standard of living. This study documents the change of intestinal parasitism pattern and deterioration of the health of Amerindians by the process of acculturation.

A seroepidemiological study of amebiasis in adults in Maracaibo, Venezuela.

Eight hundred and forty-eight sera collected from adult patients attending the Central and University Hospitals and from blood donors at the Blood Bank in Maracaibo, Venezuela, were screened for serologic evidence of Entamoeba histolytica infection, employing the indirect hemagglutination test. The seropositivity rates obtained ranged from 4.4-6.5% and most of the positive sera showed low titers of 1:128-1:256. A predominance of positive reactors was observed in the first decades of life with a decline after 44 years of age. Parasitologic examinations made in the Central Hospital population revealed E. histolytica infection in 4% of the patients.

Cryptosporidiosis among patients with acquired immunodeficiency syndrome in Zulia State, Venezuela.

We studied the prevalence of Cryptosporidium in 29 patients with acquired immunodeficiency syndrome (AIDS) from Zulia State, Venezuela. They ranged in age from five months to 46 years. Two were children and 27 were adults, of which six were women. Of the 21 men, 66.6% reported homosexual behavior. Three stool samples from each patient were examined, and modified Ziehl-Neelsen carbolfuchsin staining of formalinether stool concentrates was used to identify Cryptosporidium oocysts. To detect the presence of other intestinal parasites, direct wet mounts and iron-hematoxylin-stained smears were examined. Cryptosporidium was found in 12 (41.3%) of the patients and was identified as a single parasitic infection in seven of the 12 patients (58.3%). Other pathogenic parasites encountered were Giardia lamblia (3 of 12, 25%), Entamoeba histolytica (1 of 12, 8.3%), Ascaris lumbricoides, Trichuris trichiura, and Strongyloides stercoralis (each 1 of 12, 8.3%). Blastocystis hominis, an organism with an uncertain taxonomic position and pathogenicity, was observed in three of 12 patients (25%). An inflammatory exudate was observed in 10 of 12 patients infected with Cryptosporidium. Most of the patients with this infection presented with chronic watery diarrhea and weight loss. Our results suggest that Cryptosporidium is very common in AIDS patients with diarrhea in Venezuela. However, the role of this parasite as an enteropathogen in these patients is uncertain.

Seroepidemiology of toxoplasmosis in amerindians from western Venezuela.

A survey of 447 Amerindians aged 1-69 years (mean age, 18.6 +/- 15.8 years) in 3 mountain and 1 lowland communities from Venezuela were studied to determine the seroprevalence of Toxoplasma gondii, the environmental risk factors for the infection, and how the process of acculturation may affect the transmission rate. Serum samples were tested for immunoglobulin G antibodies by a commercial indirect hemagglutination test. The overall prevalence of infection was 49.7% (222 of 447) and ranged 38.2-62.4%. A higher antibody rate was found in the lowland setting as compared with those from the mountain area (P < 0.001). The geometric mean titer in the overall population was 280.3. No age-antibody association was detected in the mountain communities, although a gradual increase in positivity with increasing age (P < 0.01) was observed in the lowland setting, reaching a peak of 83.3% in the oldest group. The results suggest that transmission by infective cat feces may play a predominant role in the spread of infection in this population. This study demonstrates the environmental Toxoplasma infection pressure in this sylvatic population and how transmission rate is facilitated by environmental changes produced by acculturation.

Cyclospora cayetanensis infections among diarrheal patients from Venezuela.

The prevalence and importance of Cyclospora cayetanensis as an enteropathogen among 71 patients (22-45 years old) with acquired immunodeficiency syndrome (AIDS) and 132 children with diarrhea (0-12 years old) from Venezuela was assessed retrospectively. Two to three stool samples from each patient attending our parasitology laboratory for parasitologic and medical assistance were examined. For identification of the coccidium, modified Ziehl-Neelsen carbolfuchsin staining of formalin-ether stool concentrates was used, and for other intestinal parasites, iron-hematoxylin-stained smears and formalin-ether concentrates were examined. Cyclospora oocysts were found in seven (9.8%) of 71 AIDS patients and seven (5.3%) of 132 children with diarrhea. Other pathogenic parasites were present in most of the patients (9 of 14, 64.3%) shedding oocysts. Cyclosporiasis predominated in children 2-5 years of age with respect to those < or = one year of age (P < 0.05). The findings suggest that C. cayetanensis is common in diarrheal patients from Venezuela. However, the role of the parasite as the causal agent of diarrhea in these patients is uncertain.

Cryptosporidium infections in a suburban community in Maracaibo, Venezuela.

A point prevalence survey for Cryptosporidium was conducted in 212 subjects two months to 70 years of age in a suburban area with a low socioeconomic status in Maracaibo City, Venezuela. Single stool specimens were collected and modified Ziehl-Neelsen carbol-fuchsin staining of 10% formalin-preserved stool was used to identify Cryptosporidium oocysts. Direct wet mounts, iron-hematoxylin-stained smears and formalin-ether concentrates were examined to determine the presence of other intestinal parasites. Cryptosporidium infections were identified in 21 subjects (9.9%), with a high percentage of asymptomatic carriers (15 of 21, 71.4%). Six children (28.5%) had gastrointestinal symptoms and four of them were infants. Cryptosporidium was the single detectable potential pathogenic parasite in only five (23.8%) of 21 patients. The infection rate with one or more parasites was high (82%) and multiple infections, including pathogenic helminths and protozoa, were observed in the majority of patients who passed oocysts. Our findings suggest that although Cryptosporidium is an important pathogen, the proportion of asymptomatic carriers may be high in areas of low socioeconomic status in developing countries.

Cryptosporidium parvum in children with diarrhea in Zulia State, Venezuela.

The prevalence and importance of Cryptosporidium parvum as a causal agent of acute diarrhea among pediatric patients from Zulia State, Venezuela was assessed. Single stool specimens were collected from 310 children 0-60 months of age with acute diarrheal disease who were admitted to three public hospitals and from 150 comparable control children without gastrointestinal symptoms who were seen as outpatients. Cryptosporidium parvum oocysts were identified in 35 (11.2%) of 310 children with diarrhea and the coccidium was the single detectable pathogen in only 12 (34.2%). Other potential pathogenic parasites were present in most of the patients shedding oocysts (23 of 35, 65%). In nondiarrheal control children, oocysts were identified in nine (6%) of 150. The data suggest that C. parvum is relatively highly endemic in children 0-60 months of age in Zulia State and that although C. parvum may be an important pathogen associated with diarrhea, it may be a cause of only a small proportion of diarrheal episodes.

A seroepidemiological study of amebiasis in children of low socioeconomic level in Maracaibo, Venezuela.

Sera collected from 606 children of low socioeconomic level attending the University and Children's hospitals in Maracaibo, Venezuela, were screened for serologic evidence of Entamoeba histolytica infection, employing the indirect hemagglutination test. The seropositivity rate was 7.7%. Most of the positive sera showed low titers (1:128-1:256). The overall prevalence of positive reactors increased with age. Stool examinations done on 516 children revealed cysts or trophozoites of E. histolytica in 4.4%.

Melatonin prolongs survival of immunodepressed mice infected with the Venezuelan equine encephalomyelitis virus.

Male albino mice immunodepressed after the injection of dexamethasone (DEX) were inoculated intraperitoneally with the Guajira strain of Venezuelan equine encephalomyelitis (VEE) virus. Melatonin (MLT) was administered daily, at a dose of 500 micrograms/kg bodyweight, for 3 days before virus inoculation and 10 days after. Serum levels of granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-2 (IL-2) were determined in all the experimental groups (control, DEX, DEX + MLT, DEX + VEE, DEX + VEE + MLT, VEE and MLT). At day 6 after the virus inoculation, the survival rate was significantly increased from 0% in group DEX + VEE to 32.5% in the group of immunodepressed infected mice treated with MLT (DEX + VEE + MLT). By day 10 a survival rate of 10% was found in group DEX + VEE + MLT and 0% in group VEE. No alterations in IL-2 serum levels were observed. MLT increased GM-CSF in control and in DEX-treated mice. In the VEE virus-infected mice treated with DEX, serum levels of GM-CSF increased progressively from day 1 to 5 postinoculation. In contrast, the levels of GM-CSF in infected immunodepressed mice treated with MLT decreased significantly from day 1 to 5 postinoculation. At day 5 after viral inoculation, no differences were detected in the cerebral viral titres in groups VEE, DEX + VEE and DEX + MLT + VEE. These results show that MLT does not inhibit VEE viral replication in the brain of immunodepressed mice.

[Seroepidemiologic study of amebiasis in a community of the State of Zulia, Venezuela]. / Estudio seroepidemiológico de la amibiasis en una comunidad del Estado Zulia, Venezuela.

In the present evaluation, a community of low socioeconomical conditions from Zulia State, Venezuela, was analyzed for the prevalence of antibodies to E. histolytica. Two hundred and eighty three serum samples were collected and examined by the indirect hemagglutination test according to a microtiter modification of the KESSEL and LEWIS method, as used by MILGRAM et al. Antigen prepared from axenically-grown. E. histolytica strain HK9 in Diamond's medium was used. The seropositivity rate obtained was 46.6% and the frequency of positive cases was dependent on age. The antibody profiles obtained suggest a high endemicity for this parasitic infection in the area studied, with a much higher level of transmission than invasive amebiasis.

[Systemic strongyloidiasis. Review]. / Estrongiloidiasis sistémica. Revisión.

In Venezuela, Strongyloides stercoralis is an endemic parasite, but scarce information exists about systemic strongyloidiasis, an opportunistic infection that generally occurs in immunosuppressed patients, especially in those with a defect in cell-mediated immunity. The symptomatology of systemic strongyloidiasis is variable. The syndrome is characterized mostly by gastrointestinal and respiratory symptoms. Paralytic ileus and acute respiratory insufficiency can be prominent. Sepsis and meningitis are frequent. The diagnosis can be made by examination of feces, duodenal or jejunal aspirates and sputum. Larvae can also be identified in peritoneal fluid, pleural fluid, lymph nodes, urine specimens and cerebrospinal fluid. Thiabendazole, at standard doses, during at least five to seven days is satisfactory if administered promptly. It is necessary to rule out this parasitoses in patients at risk to avoid fatal outcomes.

[Relevance of Entamoeba dispar in amebiasis]. / Relevancia del reconocimiento de Entamoeba dispar en la amibiasis.

Entamoeba histolytica was redefined to recognize the existence of two morphologically indistinguishable species but genetically distinct: E. histolytica and E. dispar. The former is a pathogen responsible for amebiasis while the latter is a commensal. This redefinition has dramatically changed the understanding of amebiasis and its clinical management.

[Importance of the different species and genotypes of Cryptosporidium in public health]. / Importancia de las diferentes especies y genotipos de Cryptosporidium en Salud Pública.

Until recently, only the bovine and human genotypes of Cryptosporidium parvum had been considered to infect man and to be potential pathogens. Lately, symptomatic infections with C. felis, C. meleagridis, and C. parvum-like dog genotype have been described in immunocompetent and immunosuppressed individuals. These findings suggest that zoonotic parasites could also play an important role in Public Health.

[Cryptosporidiosis in humans. Review]. / Criptosporidiosis en humanos. Revisión.

Cryptosporidiosis basically is a gastrointestinal infection caused by the coccidian protozoa Cryptosporidium. The infection is associated with diarrhea worldwide but it is most prevalent among children below 5 years of age in the undeveloped countries. It is an important Public Health problem. Infection in humans is usually with C. parvum. The parasite appears to be transmitted by a variety of mechanisms but zoonotic- and person-to-person transmission, and contaminated water appear to be the most important. The mechanism by which the coccidium causes diarrhea is unknown. The extent of the disease is mostly dependent on the immune status of the host. In immunocompetent persons, C. parvum may cause a short term diarrheal disease that resolves spontaneously; in immunocompromised patients, especially those with AIDS, produces a prolonged, life-threatening cholera-like disease. The diagnosis is generally made by detection of oocysts in stools by means of several concentration and staining procedures. Modified acid-fast and fluorescence stains are widely used. Immunofluorescent assays with Cryptosporidium-clonal antibodies have been developed to detect oocysts in stool specimens. Specific humoral antibodies have been detected by immunofluorescence and enzyme-linked immunosorbent assay techniques. Although an effective agent for Cryptosporidium is not available yet, promising results have been related to the immunotherapy. Vaccines are not available and the control and prevention of the infection is limited because of the environmentally resistant oocysts and the ignorance of all its possible transmission routes.

[Prevalence of Entamoeba histolytica and other intestinal parasites in a neighborhood of the Mara Municipality, Zulia State, Venezuela]. / Prevalencia de Entamoeba histolytica y otros parásitos intestinales en un barrio del Municipio Mara, Estado Zulia, Venezuela.

A parasitologic survey of a low socioeconomic level community from Mara County, Zulia State, Venezuela was done. A single stool specimen per person from 327 individuals was obtained and examined by hematoxylin stained fecal smears and formol-ether concentrates. The overall parasitic infection rate was 92%. Multiple infections were present in 89% of the population. The amebic prevalence rate (APR) was 41.5%. Entamoeba histolytica was found in 9.2% of the individuals, most of them being asymptomatic. Haematophagous trophozoites were observed in two symptomatic cases. Entamoeba coli was the most frequent protozoan (23.5%). The APR was high in all groups. In males it was higher in 7-12 year old children and adolescents, and in females it was higher in adults. Giardia lamblia was the most frequent flagellate (18%) and among the helminths, Trichuris trichiura (82.8%) and Ascaris lumbricoides (74.6%). The high rates of parasitic infection, multiple parasitosis and amebic prevalence reflect the low socioeconomic conditions in the population.