Leonardo Mata

The pathogenesis of Shigella Diarrhea: I. Enterotoxin production by Shigella dysenteriae 1

A strain of Shigella dysenteriae 1, freshly isolated from a patient with dysentery in Guatemala in August 1969, was found to elaborate an enterotoxin into the liquid of broth cultures. Partial purification of the enterotoxin by ultrafiltration on graded polymeric membranes and Sephadex gel filtration (Pharmacia Fine Chemicals, Inc., Piscataway, N. J.) suggested an approximate molecular weight of 55,000-60,000. The partially purified toxin was heat-labile, pronase sensitive, and activated by alkaline pH, and it elicited fluid production in ligated rabbit ileal segments; it failed, however, to cause increased vascular permeability in skin. When the activities of equal weights of identically prepared Vibrio cholerae and S. dysenteriae enterotoxins were compared in the rabbit ileum the latter caused a significantly smaller volume response with increased concentrations of potassium, chloride, and protein. The previously described neurotoxic (mouse lethal) factor was also present and eluted from Sephadex G-150 with the enterotoxin. If these biological activities prove to be possessed by a single molecular species, it is suggested that it be renamed Shigella enterotoxin in recognition of the physiologically more relevant biological action.

Nasopharyngeal colonization in Costa Rican children during the first year of life

BACKGROUND The establishment of the nasopharyngeal flora was followed in Costa Rican children from birth to 1 year of age. METHODS Nasopharyngeal cultures were obtained at 1 (n = 413), 3 (n = 393), 6 (n = 376) and 12 months (n = 356) of age from children representative of the population in the Puriscal district. Weekly cultures were obtained from a subcohort of these children (n = 101). Mother-infant diads (n = 95) and preschool children (n = 208) attending day-care centers were also studied. RESULTS The estimated proportion of colonized children in the population differed markedly depending on the frequency of culture. Quarterly cultures showed a slow increase in carrier rates from 3.9% for Haemophilus influenzae, 3.1% for Streptococcus pneumoniae and 6.5% for Moraxella catarrhalis at 1 month of age to 10.1% carrying H. influenzae and 19.4% carrying S. pneumoniae by the end of the first year. By quarterly culture the proportion of children colonized at least once was 36% for S. pneumoniae, 26% for H. influenzae and 28% for M. catarrhalis. In contrast weekly sampling showed that 95 to 100% of the children were colonized at least once during the first year of life with H. influenzae, S. pneumoniae or M. catarrhalis. Nasopharyngeal carriage of H. influenzae, S. pneumoniae and M. catarrhalis was low in the mothers, and very few mother-infant pairs carried identical bacteria at the same time. In contrast carrier rates were high in the siblings attending day care (H. influenzae 27.9%, S. pneumoniae 39.4%, both organisms 26.6%). Infants with siblings had significantly higher bacterial carriage at all ages than infants without siblings. CONCLUSIONS Quarterly nasopharyngeal cultures showed that Costa Rican infants acquire their nasopharyngeal flora at a rate comparable with that for infants in developed countries and that siblings are an important source of the bacteria. Weekly samplings showed that virtually all children were colonized at least once during the first year of life.

Secretory antibody directed against rotavirus in human milk—measurement by means of enzyme-linked immunosorbent assay

Human milk contains antibodies to a variety of enteropathic agents. We utilized the method of enzyme-linked immunosorbent assay to investigate anti-rotavirus secretory IgA in 113 human milk and colostral specimens from a rural area in Guatemala, 32 colostral specimens from an urban area of Costa Rica, and 12 from an urban area of the United States. Anti-rotavirus SCIgA was found in all colostral samples and in 94% of the milk specimans. Both the absolute concentration of anti-rotavirus SCIgA and concentration relative to total SCIgA were highest in colostrum, falling to lower but detectable levels from one week to two years after birth. No significant differences were noted in the results from the specimens from the three different geographic areas. The possible role of this antibody in immunity to rotavirus infections is discussed.

Treatment of 242 neonates with dehydrating diarrhea with an oral glucose-electrolyte solution

Two hundred thirty-four of 242 neonates (96.7%) with a mean dehydration of 5.1% body weight were rehydrated with a glucose-electrolyte solution given orally in an average time of 7 44 hours. Eight (3.3%) neonates required intravenous fluid therapy. Emesis was not an obstacle for complete oral rehydration. Hypernatremia, hyponatremia, and acidosis present on admission were corrected within a few hours. Oral rehydration is an entirely satisfactory choice for treatment of uncomplicated dehydration in neonates.

Sociocultural Factors in the Control and Prevention of Parasitic Diseases

Control and prevention of parasitic disease depends on an adequate knowledge of interactions among factors such as human behavior, the environment, and the life cycles of parasites. Sociocultural factors in large part determine transmission and persistence of parasites. The main determinants are poverty, low educational level, deficiencies in home technologies, high demographic density, and ruralism. Selected interventions designed to improve any of these situations may fail if they are applied in an isolated manner. The holistic implementation of interventions has proved successful in the control and prevention of parasitic infections in several parts of the word. The implementation of several kinds of interventions simultaneously, that is, a holistic approach, combined with an awareness of a societys infrastructure, can produce favorable results. For such an awareness--when it provokes action--can improve the overall quality of life.

ORAL REHYDRATION OF NEONATES WITH DEHYDRATING DIARRHŒAS

Thirty-nine of forty neonates with mean dehydration equivalent to 6.7% of body-weight were orally rehydrated with a glucose/electrolyte solution. Only one patient required any intravenous fluids for rehydration. Hypernatraemia and acidosis present at admission were corrected within a few hours without complications. It seems that oral rehydration, is suitable for neonates as well as for children and adults.

ANTI-ROTAVIRUS ANTIBODY IN HUMAN COLOSTRUM

reporte de investigacion -- Universidad de Costa Rica, Instituto de Investigaciones en Salud. 1978. Una pagina. Este documento es privado debido a limitaciones de derechos de autor.

Infection and Low Birth Weight in a Developing Country: A Study in an Indian Village of Guatemala

articulo -- Universidad de Costa Rica, Instituto de Investigaciones en Salud. 1975. Este documento es privado debido a limitaciones de derechos de autor.

Titres of class-specific antibodies against Shigella and Salmonella lipopolysaccharide antigens in colostrum and breast milk of Costa Rican, Swedish and Vietnamese mothers

Enzyme immunoassays (EIA) were used to estimate titres of class-specific antibodies against purified and chemically defined phenol-water-extracted lipopolysaccharide (LPS) antigens of Salmonella serogroup B (BO), Shigella dysenteriae type I, Plesiomonas shigelloides (the same O-antigen as Shigella sonnei) and Shigella flexneri Y. Titres in colostrum and breast milk of Swedish, Vietnamese and Costa Rican mothers from various socioeconomic conditions were compared. The antibodies were mainly of the IgA isotype. IgM antibodies were also present, but only very low concentrations of IgG were found. In Costa Rican mothers, the IgA antibody titres were significantly higher (P less than 0.05) in women of low and middle socioeconomical conditions than were those in mothers of high socioeconomical level. The low titres in the last group were comparable to those found in Swedish mothers. The IgA antibody titres found in Vietnamese mothers were similar to those of Costa Rican mothers from the low and middle socioeconomic conditions, being highest against S. flexneri Y LPS. The IgM antibody titres were also highest in Vietnamese mothers, immediately followed by the Costa Rican mothers of low socioeconomic conditions. The low IgM titres in the Costa Rican women of high socioeconomic level were comparable to those seen in Swedish mothers. The results suggest that, in Costa Rica and Vietnam, S. flexneri is the most prevalent Shigella sp. causing infection and that Salmonella serogroup B infections are rare in all three countries. The results also show that the antibody repertoire in colostrum and breast milk varies. Furthermore, in addition to the prevalence of a specific micro-organism in a determined geographical area, such differences may be associated mainly with exposure to certain pathogens in particular socioeconomic conditions.

Cutaneous leishmaniasis in rural Costa Rica

Articulo cientifico (reporte corto) -- Universidad de Costa Rica. Instituto de Investigaciones en Salud, 1989