Biomedical subjects
Publications and source records attributed to H Bolaños.
Vibrio mimicus contamination of sand increased significantly during the arrival of the olive ridley sea turtles (Lepidochelys olivacea) at Ostional anidation beach, Costa Rica. Statistical analysis supports that eggs are contaminated with V. mimicus by contact with the sand nest. V. mimicus was isolated from eggs of all nests tested, and ctxA+ strains were found in 31% of the nests, all of which were near the estuary.
Clinical and epidemiological characteristics of diarrhea associated with Vibrio mimicus were identified in 33 hospitalized patients referred to the Costa Rican National Diagnostic Laboratory Network between 1991 and 1994. The relevant symptoms presented by patients included abundant watery diarrhea, vomiting, and severe dehydration that required intravenous Dhaka solution in 83% of patients but not fever. Seroconversion against V. mimicus was demonstrated in four patients, from whom acute- and convalescent-phase sera were obtained. Those sera did not show cross-reaction when tested against Vibrio cholerae O1 strain VC-12. All the V. mimicus isolates from these cases produced cholera toxin (CT) and were susceptible to commonly used antibiotics. Attempts to isolate this bacterium from stool samples of 127 healthy persons were not successful. Consumption of raw turtle eggs was recalled by 11 of the 19 (58%) individuals interviewed. All but two V. mimicus diarrheal cases were sporadic. These two had a history of a common source of turtle (Lepidochelys olivacea) eggs for consumption, and V. mimicus was isolated from eggs from the same source (a local market). Among the strains, variations in the antimicrobial susceptibility pattern were observed. None of the strains recovered from market turtle eggs nor the four isolates from river water showed CT production. Further efforts to demonstrate the presence of CT-producing V. mimicus strains in turtle eggs were made. Successful results were obtained when nest eggs were tested. In this case, it was possible to isolate CT- and non-CT-producing strains, even from the same egg. For CT detection we used PCR, enzyme-linked immunosorbent assay (ELISA), and Y-1 cell assay, obtaining a 100% correlation between ELISA and PCR results. Primers Col-1 and Col-2, originally described as specific for the V. cholerae O1 ctxA gene, also amplified a 302-bp segment with an identical restriction map from V. mimicus. These results have important implications for epidemiological surveillance in tropical countries where turtle eggs are used for human consumption, serving as potential sources of cholera-like diarrhea.
Information about Mycoplasma pneumoniae infections in tropical countries is scarce. This study reports the prevalence of anti-M. pneumoniae antibodies among schoolchildren from the tropical community of Palmares, Costa Rica. The serum samples were collected in July 1983 from 2021 children who represented 99% of the county's schoolchildren. Immunofluorescence (IFA) and in some cases ELISA serological methods were applied. IFA seropositivity was high (53%) and ranged from 22% to 79% depending on the district. Marked differences in the prevalence of antibodies in children attending schools of neighboring communities, suggest that the school may be epidemiologically important as a focus to spread mycoplasma infections among children. The presence of a low percentage of antibodies (IgG, IgM and IgA) against the 168 kd- M. pneumoniae antigen suggested that there were few cases of active or recent infections.
A single 500 mg dose of tinidazole was given to fourteen healthy volunteers. Cellular immune functions were studied, before and 2 and 24 h after drug ingestion. Blast transformation of lymphocytes to Con-A was significantly lower (P less than 0.01) in samples obtained 2 h after ingestion. No significant changes were found in the other immunological parameters studied. We conclude that these findings could be caused by reversible blockage of lectin binding receptors on the lymphocyte surface.
This report summarizes both a prospective study of diarrhea in cohorts of rural children in their natural ecosystem, and a vertical study of diarrheic urban children attending a hospital emergency service. Cryptosporidium oocysts were found in feces of 4.3% of the cases, while all controls were negative. No infection occurred in the first year of life among rural infants, contrasting with a 3% infection rate in children under 1 year of age in the metropolitan area. This could be attributed to intense and exclusive breast-feeding for several months in the rural area while in the urban area many infants are not breast-fed at all, or are weaned prematurely. No infection was found in wholly breast-fed infants. Diarrhea associated with Cryptosporidium was watery and without inflammatory cells. Dehydration was common in urban children, but was rapidly corrected by oral rehydration therapy, or by intravenous fluid therapy in some cases. Infections clustered in the warmer, rainy and humid months of the year.
The present report is a systematic study of children, with and without diarrhea from Costa Rican metropolitan areas and southern rural higlands. Children were observed, respectively, at emergencies, Hospital Nacional de Niños, and in a field station in Puriscal; urban children were studied vertically, rural children were observed prospectively (cohort study). Cryptosporidium sp. was found in 4.3% of the cases of diarrhea; diarrhea was generally severe in urban children, but mild in the rural. Infection was detected in urban children less than one year of age: contrasting, no rural infants were found infected, which might be related to breast-feeding, since Puriscal infants were intensively breast-fed for several months, while many urban infants were not breast-fed or were weaned earlier. Cryptosporidium sp. appeared during the warm, rainy and humid months of May through August, when the coccidium was associated with 14.8% of the urban and 15.4% of the rural diarrheas. All urban cases presented dehydration which was corrected with oral rehydration salt therapy, and occasionally with intravenous fluids; dehydration was not common in the rural cases.
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This is the first report of Ureaplasma sp. from the reproductive tract of Costa Rican cows. Among 204 animals sampled from 11 dairy farms in the country's Central Plateau, the infection rate was 0-71%. Isolation was more frequent in vulvo-vestibular (38.7%) than in cervical swabs (23%). Ureaplasma was correlated with clinical granular vulvitis symptoms.
A case-control study, determined the influence of breed, age and number of deliveries as risk factors for Ureaplasma genital infections in Costa Rica dairy cattle. The animals with none or one delivery had a risk of infection 2.99 times higher than those with several parturition, regardless of breed. The risk was 1.95 times higher in Jersey than in Holstein, and decreased progressively until three deliveries. In cows with four deliveries there was a significant increase in the amount of animals infected and also a significant difference in the rate of infection between Holstein (27%) and Jersey (64%). Ureaplasma isolation was rare in cows with more than six deliveries.