Loss maternally derived measles immunity in Argentinian infants.

BACKGROUND: Measles immunization of children at 1 year of age with a single dose of the current vaccine has successfully reduced measles incidence in Argentina. However, the optimal schedule of measles vaccination of young infants would balance the risk of early loss of maternal antibody in the majority of infants with the risk of primary vaccine failure because of passive measles immunity. This study is the first to document a significant association between loss of passive measles antibody and age among infants born in 1995 and 1996 in Córdoba City, Argentina. METHODS: This is a seroprevalence study of 340 infants to investigate the duration of transplacentally derived measles antibody, assayed by a neutralization test, during the first 8 months of age in Córdoba City, Argentina. RESULTS: The proportion with detectable neutralizing measles antibodies decreased from 85% at 1 month of age to 8% at 8 months of age. The simple logistic model with age (in weeks) as the only variable showed that the decline in the proportion of infants with a positive antibody titer was sharpest during the second and fifth months of age (6.6 and 6.8% per week during a 4-week period, respectively). CONCLUSIONS: These findings suggest that 80% of infants are susceptible to measles infection for at least 3 months before routine immunization at 12 months of age.

Neuroendocrine changes produced by competition stress on the Thoroughbred race horse.

1. Packed cell volume (PCV) and plasma catecholamines, cortisol and glucose were determined in blood samples obtained from race horses, after competition. 2. All these parameters were higher than basals but catecholamines increased 6-7 times while cortisol was enhanced only by 25%. 3. The increase of glucose and PCV was related to the rise of catecholamines. 4. In samples withdrawn after overnight stress caused by change of horseshoes, it was not possible to find values from basal values significantly different. 5. Influence of nervous temperament was observed only in the higher hematocrit found in basal conditions, particularly in females.

Detection of picobirnavirus in HIV-infected patients with diarrhea in Argentina.

Diarrhea due to enteric pathogens is an important complication of advanced HIV infection. Picobirnaviruses are agents recently linked with human enteritis. In total, 197 fecal samples collected from HIV-infected and noninfected patients with and without diarrhea were investigated for the presence of rotavirus and picobirnavirus by polyacrylamide gel electrophoresis. Picobirnavirus was detected in 8.8% of 57 HIV-infected patients with diarrhea, but it was detected in neither those without diarrhea (p<.018) nor in the group of subjects uninfected with HIV (p<.022). All genomic electropherotypes of picobirnavirus strains had a wide pattern. Picobirnavirus genome segments varied in size between 2.4 and 2.7 and 1.6 and 1.9 kbp for the slow and fast migrating bands, respectively. Rotaviruses were not detected in any of the clinical groups studied. Two methods for the extraction of nucleic acid-phenol/chloroform and guanidinium thiocynate (GTC)/silica-were compared. Detection of picobirnavirus by polyacrylamide gel electrophoresis was 2.5 times more sensitive following guanidinium thiocynate RNA extraction. This investigation offers preliminary results about the circulation of picobirnavirus in HIV-infected patients in Córdoba, Argentina.

PIP: In 1988, a new group of viruses containing a bisegmented double-stranded RNA genome was described and named "picobirnavirus" (PBV). Viruses with similar properties have subsequently been found in fecal specimens collected from HIV-infected and noninfected patients with gastrointestinal symptoms in several countries. The present study used polyacrylamide gel electrophoresis (PAGE) to examine fecal specimens from 197 HIV infected and noninfected adults, with and without diarrhea, from Cordoba, Argentina, for rotavirus and PBV. PBVs were detected in the stools of 5 HIV-infected patients with diarrhea (8.8%), but in none of the other subgroups (HIV-positive patients without diarrhea, HIV-negative patients with diarrhea, HIV-negative patients without diarrhea). 3 of the 5 stool samples positive for PBV were also positive for intestinal parasites (mixed infection), but these parasites were found with equal frequency in HIV-infected patients without diarrhea. Rotaviruses were not detected in any of the subgroups. PBV genome segments varied in size between 2.4-2.7 and 1.6-1.9 kbp for the slow and fast migrating bands, respectively. PBV detection by the PAGE technique was 2.5 times more sensitive after guanidinium thiocyanate RNA extraction. Further research is required to determine the duration of excretion of PBVs in HIV-infected patients with diarrhea and understand the immune response to infection.