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Biomedical subjects

A Ruiz

Publications and source records attributed to A Ruiz.

At least 307 records · Page 17Linked to original sources
PubMed1981

Endemicity of toxoplasmosis in Costa Rica.

Toxoplasma infection can be transmitted to humans by ingestion of tissue cysts in meat or by ingestion of oocysts in cat feces or fecally contaminated soil. since meat is traditionally well cooked in Costa Rica and the authors were able to exclude meat and eggs from playing a role in transmission, they postulated that ingestions of oocysts should entirely explain transmission. To test this hypothesis, they studied seven populations in Costa Rica and serologically tested 883 people between 15 and 26 years of age. By interviews and surveys, they determined mode of living, soil contact, cat contact, and cat density. The infection rate in cats was studied by stool and serologic examination, and soil availability for defecation was determined from aerial photographs. Antibody was taken as indicating infection and was found to be acquired most actively in children and young cats. In a retrospective analysis, antibody prevalence in humans correlated highly with individual cat contact (both owned and stray), with cat density, with living in houses with wood floors and a crawl space underneath, and with living with cats on a cement floor. antibody prevalence in humans correlated negatively with soil availability to cats for defecation and with soil contact by humans, suggesting that oocysts may be transmitted optimally near house in areas where most terrain is covered by asphalt and concrete and little soil is available for defecation or for human soil contact. Cats acquire infection by eating intermediate hosts; 16% sparrows, 3.5% of mice and 12.5% of rats have been found infected. Favoring transmission are young non-immune cat populations, shade and moisture, older intermediate hosts, a high percentage of which have become infected, and concentration of houses in city blocks. Transmission is diminished when houses are dispersed or arranged along a road in an open rural setting, permitting dispersal of cat fecal deposits.

Adolescent↗
PubMed1981

Particle size of airborn Cryptococcus neoformans in a tower.

Nearly 10(6) cells of Cryptococcus neoformans were cultured per g of pigeon droppings in a vacant tower. The air in the tower contained an average of 45 viable cells of C. neoformans per 100 liters: 60% of the cells were less than 4.7 micron in diameter. It is estimated that a human exposed to this atmosphere for 1 h would have 41 cells of c. neoformans deposited in the lungs. Sweeping resulted in the aerosolization of large numbers of cells of C. neoformans from 4.7 to 11 micron in diameter, the number of cells less than 4.7 micron remained relatively constant. One minute after sweeping, 4.4% of viable airborne cells of C. neoformans were less than 1.1 micron in diameter. We believe that this is the first report of isolating such small cells of C. neoformans from a natural site.

Aerosols↗
PubMed1981

Distribution of Cryptococcus neoformans in a natural site.

Pigeon droppings in a vacant tower were assayed for the number and size of viable cells of Cryptococcus neoformans. The dry, thinly scattered floor debris contained 2.6 x 10(6) viable cells per g--300 times more cells than were cultured from a large, compact pile of pigeon droppings (7.4 x 10(3) cells per g). Aerosols generated from floor debris containing pigeon droppings had an average of 360 viable cells in 31 liters of air; 27 of these cells (7.5%) were 1.1 to 3.3 micrometers in diameter and, therefore, capable of human lung deposition. Environmental factors which may influence the distribution, survival, and proliferation of C. neoformans in nature are discussed.

Aerosols↗
PubMed1981

[Coma states induced by craniocerebral injuries in children. Review of 20 cases].

From a total of three-hundred and fifty-six children admitted into the Department of Pediatrics at the Hospital Clínico of the University of Granada during of period of two years, twenty cases that needed admittance in critical pediatrics care unit are revised. Organic etiology that provoked coma, time of appearance, intensity, evolution, complications and short term outcome are analysed. A comparison is made of the incidences and prognosis of this type of coma with that of other authors presenting therapeutic outline carried. Two large evolutive groups; one which consisted of nine patients which entered into coma immediately after injury. The second group includes those patients which had lucid period before entering into coma. Following conclusions have been withdrawn: Severity and duration of coma does not have a definite relationship with the existence of a mass-lesion. Presence of an associated--mass-lesion is a sign of grave prognosis. For a good therapeutic response the following approaches are necessary: Immediate assistance monitoring and periodic or systematic maintenance of extracranial variants diagnostic, and treatment of the primary causing factor.

Brain Injuries↗
PubMed1980

Toxoplasma gondii in Costa Rican cats.

Toxoplasma gondii infection of cats was studied in seven localities in Costa Rica. A total of 237 cats were tested for antibody by the dye test, and for oocysts by injection into mice. Toxoplasma was isolated from 55 (23%) and antibody was found in 109 (46%). Sixty percent of cats were infected as shown by shedding or antibody. Of the 55 isolations, 64% were from kittens without antibody and 36% from kittens with antibody. Almost half of the Toxoplasma isolations were made from the feces of kittens weighing less than 600 g, 35 cm in length, or under 2 months of age, of which 41% were shedding Toxoplasma. Six hundred and seventy-six homeowners in the seven towns were questioned about the number of owned and stray cats visiting their houses, the cats' pattern of roaming, food sources, types of food foraged, defecation sites outdoors and indoors, and location of fecal deposits in houses. Seventy-six percent of houses reported cats, which averaged 2.1 cats per house; about 80% were strays, and 99% lived outdoors part or all of the time. The cats visited from 5-12 (average 6) houses, foraging for food in garbage, hunting mice, rats, sparrows and insects. Of the 516 households reporting cats, 29% supplied some food in addition. In 14% of these houses cats defecated in the house, including the false attic and crawl space; they commonly defecated in front and backyards of houses, close to human habitation and accessible to intermediate hosts.

Animals↗
PubMed1980

Intermediate and transport hosts of Toxoplasma gondii in Costa Rica.

Toxoplasma gondii was isolated from 3.5% of 202 Mus musculus, 12.5% of 120 Rattus norvegicus, 16% of 106 sparrows (Zonotrichia capensis), and from 54% of 50 chickens from Costa Rica. The infection rate in chickens increased from 23% in those weighing less than 500 g, to 73% in those between 500 and 1,000 g, indicating a rapid rate of acquiring infectin, probably from the soil in which they constantly search for food. No isolates were made from Musca domestica, or from four genera of roaches caught in the wild. However, Toxoplasma was isolated from four of 16 lots of earthworms. Most strains of Toxoplasma isolated from Costa Rican cats produced chronic latent infections in mice. However, even when infected with virulent strains, mice died at a time when numerous bradyzoites had been formed. Also, the availability of bradyzoites in chickens 8-10 days after ingestion of oocysts was comparable to that in mice. Therefore, several infected prey species are available as intermediate hosts to cats, providing the bradyzoites essential for the shedding of large numbers of oocysts. The isolation of Toxoplasma from earthworms or the soil associated with them illustrates their possible role as transport hosts to infect chickens and other birds feeding on them. The possible role of other transport hosts could not be confirmed.

Animals↗
PubMed1980

Human toxoplasmosis and cat contact in Costa Rica.

We studied the prevalence of antibody to Toxoplasma gondii in 883 Costa Ricans between the ages of 15 and 26 years (mean 20.3). There were seven populations, two rural and five urban. The overall antibody prevalence was 61.4%. Because antibody prevalence was 57.1% in the 14 people who ate raw meat, and 61.6% in the 294 people who consumed raw eggs, meat and eggs could be excluded as important modes of transmission. We ascertained the presence of cats, type of soil contact, and flooring in the kitchen for every residence in which each individual lived from birth until interviewed. The 66% of people who indicated contact with cats had an antibody prevalence of 64%, and those without contact 56% (P = 0.02). In six of the seven populations, we found a positive correlation between cat contact and antibody prevalence; hence these six were studied together, and San Ramon, with a negative correlation, was examined separately. In the San Jose metropolitan population and in the total urban sample, cat contact was associated with a significantly higher antibody prevalence (P < 0.01). It was found that humans, even without acknowledged soil contact, acquire infection inside houses, especially with cement floors, when cats defecate in the house. Humans also acquire infection in or around houses with wooden floors, where the crawl space is an often unrecognized refuge of cats and a source of persistent soil contamination. San Ramon was the urban area with the highest human-cat contact (77%) and with the highest antibody prevalence in cats (75%). Although suggesting equal opportunities for infection, irrespective of cat contact, we cannot be certain in a retrospective study in which most of the infections took place an average of 15 years earlier. The most frequent antibody titer in our Costa Rican population was 1:1,024 (21%), much higher than the most frequent titers in a Colombian (1:64 to 1:128) and a U.S. population (1:16) of comparable age.

Adolescent↗
PubMed1978

Clinical and pathological study of asymptomatic HBsAg carriers in Chile.

A clinical, biochemical, and pathological study was performed in 38 chronic HBsAg carriers. The study group is a part of 393 carriers found among 117 705 voluntary blood donors at the National Blood Bank, Hospital del Salvador, Santiago, Chile. None of the 38 carriers had a past history of illicit drug abuse, hepatitis, or work involving a high risk of hepatitis B virus infection. Ten individuals had a normal liver biopsy, 17 reactive non-specific hepatitis, one fatty changes, four chr onic persistent hepatitis, one aggressive hepatitis, two post-necrotic cirrhosis, and three alcoholic cirrhosis. There was not a close correlation between liver function test and liver histology. The most significant laboratory finding was the postivity of alpha fetoprotein in two cases. During the follow-up the two alpha fetoprotein patients presented a hepatocarcinoma 12 and 14 months after admission to the study.

Adolescent↗
PubMed1977

Ultrastructure of the cyst of Sarcocystis muris.

Cysts of Sarcocystis muris develop within muscle cells and each is bounded by a parasitophorous vacuole membrane. Closely spaced spherical blebs formed from this membrane extend into the muscle cell cytoplasm. A dense substance fills the cavity of the bleb and occupies the vacuolar space immediately adjacent to the membrane. The remainder of the vacuole is filled with a moderately dense matrix within which the parasites develop. At 40 days after infection only metrocytes are present, characterized by their ovoid shape, lightly stained cytoplasm, amylopectin-like granules, and lack of micronemes. Metrocytes divide by a process resembling endodyogeny and eventually produce bradyzoites. By 78 days after infection, at which time the cyst is infective for cats, the few remaining metrocytes are located at the cyst periphery but most organisms are elongated and contain organalles characteristic for bradyzoites including micronemes, dense granules, and amylopectin. Structures indicative of division were not seen in bradyzoites. Rhoptries are few in number. Numerous vesicles of smooth endoplasmic reticulum accumulate in the cytoplasm of muscle cells adjacent to the periphery of the enlarging cyst but significant destruction of muscle fibers containing cysts with viable organisms was not seen in specimens fixed between 40 and 325 days after infection. Unusual lamellar structures were seen in some parasitized muscle cells and intracystic tubules occurred in some cysts.

Animals↗
PubMed1976

Recognition of cyclic transmission of Sarcocystis muris by cats.

Sarcocystis muris, obtained from laboratory and house mice, was transmitted experimentally to cats. When cysts in the skeletal muscle of mice were ingested by cats, bradyzoites developed directly into gametes in the intestinal mucosa of the cats. After five to 11 days, infectious sporulated sporocysts (8.5 x 10.3 mum) were shed by cats for up to three months. After ingestion of the sporocysts, S. muris multiplied first in the livers and then in the skeletal muscle of mice. Cysts in skeletal muscle attained a length of 5-6 mm and were visible to the naked eye. With heavy infections the cysts outlined major muscle groups. Lesions in mice were apparently the result of degeneration or rupture of cysts, with myositis and sometimes muscle necrosis, leading to locomotor impairment in heavy infection. S. muris required approximately 76 days of development in mice before becoming infectious for cats. S. muris is perpetuated by an obligatory two-host cycle (mouse-cat). Both cats and mice could be infected repeatedly. Rats, hamsters, and guinea pigs did not become infected.

Animals↗
PubMed1975

Soil survival of toxoplasma oocysts in Kansas and Costa Rica.

Toxoplasma oocysts in cat feces were marked with a tracer amount of strontium-85 (85-SR), and were superficially buried simulating the natural disposal of feces by cats. Oocyst infectivity in Costa Rica was followed qualitatively and persisted for 1 year in three shaded sites, two moist, and one relatively dry site. Oocyst infectivity was quantitated in the Kansas deposit over a period of 18 months, including two winters. After initial mixing in soil, the level of infectivity remained fairly stable. Infectivity was recovered, probably from the surface on one Musca, several isopods, and earthworms. These data on persistence of Toxoplasma oocysts in soil support the concept that Toxoplasma infectivity in nature may be increased logarithmically by cats.

Animals↗