Temporal trends in the prevalence of asthma and rhinoconjunctivitis in adolescents

ABSTRACT OBJECTIVE To analyze the temporal trend of asthma and rhinoconjunctivitis prevalences as well as their symptoms in adolescents. METHODS Two cross-sectional studies were conducted using the same methodology and questionnaire as was used for adolescents aged 12 to 14 years in the Brazilian city of Florianopolis, SC, Southern Brazil. Based on the international protocol of the International Study of Asthma and Allergies in Childhood (ISAAC) study, adolescents were evaluated in 2001 and 3,150 in 2012. The schools included in this study were the same as in the 2001 study. These schools were randomly selected after stratification by network (public and private) and geographic location. The total average percentage variation was estimated for the prevalence of asthma and rhinoconjunctivitis and their symptoms. RESULTS The prevalence of reported asthma was 10.9% in 2001 and 14.8% in 2012, with an average variation of 2.8% in the period. The highest average variation in the period was observed among female adolescents (4.1%). In parallel a significant increase occurred in reported physician-diagnosed asthma, 7.3% in 2001 and 11,1% in 2012, with an annual variation of 4.5%. The largest increases in reported physician-diagnosed asthma were seen in female (5.9%) and male (4.5%) public school pupils. In addition, a significant increase in reported rhinoconjunctivitis occurred, with the average variation in the period being 5.2%. Reports of severe asthma symptoms remained unchanged during the period, while the annual variation for reported current wheezing (-1.3%) and wheezing during exercise (-1.2%) decreased. CONCLUSIONS The results showed a significant increase in the annual average variation for asthma and rhinoconjunctivitis prevalence during the 2001 to 2012 period.

Evaluation of temporal, seasonal and geographic stability of the molluscicidal property of Euphorbia splendens latex

Laboratory tests with aqueous solutions of Euphorbia splendens var. hislopii latex have demonstrated seasonal stability of the molluscicidal principle, with LD90 values of 1.14 ppm (spring), 1.02 ppm (fall), 1.09 ppm (winter), and 1.07 ppm (summer) that have been determined against Biomphalaria tenagophila in the field. Assays on latex collected in Belo Horizonte and Recife yielded LD90 values similar to those obtained with the reference substance collected in Rio de Janeiro (Ilha do Governador), demonstrating geographic stability of the molluscicidal effect. The molluscicidal action of aqueous dilutions of the latex in natura, centrifuged (precipitate) and lyophilized, was stable for up to 124 days at room temperature (in natura) and for up to 736 days in a common refrigerator at 10 to 12ºC (lyophilized product). A 5.0 ppm solution is 100% lethal for snails up to 13 days after preparation, the effect being gradually lost to almost total inactivity by the 30th day. This observation indicated that the active principle is instable. These properties together with the wide distribution of the plant, its resistance and adaptation to the tropical climate, its easy cultivation and the easy obtention of latex and preparation of the molluscicidal solution, make this a promising material for large-scale use in the control of schistosomiasis

Temporal association between the isolation of Sabin-related poliovirus vaccine strains and the Guillain-Barré syndrome

Thirty eight paralysis cases classified as Guillain-Barré syndrome (GBS) in Brazil were analysed. In all these cases Sabin-related poliovirus vaccine strains were isolated. In most of the cases the last vaccine dose was given months or years before the onset of GBS, suggesting a persistent infection or the transmission of the Sabin-related strains to the patients. The isolation of Sabin-related strains from GBS cases some days or weeks after the onset of the disease, demonstrated a temporal association between the isolation of the strains and the disease. Although the isolates from the GBS cases may not be the etiological agent of the disease, this study strongly indicates that infections caused by Sabin-related vaccine strains can trigger the GBS in certain cases.

Temporal differences in blood meal detection from the midguts of Triatoma infestans

We used genus/species specific PCRs to determine the temporal persistence of host DNA in Triatoma infestans experimentally fed on blood from six common vertebrate species: humans, domestic dogs, guinea pigs, chickens, mice, and pigs. Twenty third or fourth instar nymphs per animal group were allowed to feed to engorgement, followed by fasting-maintenance in the insectary. At 7, 14, 21, or 28 days post-feeding, the midgut contents from five triatomines per group were tested with the respective PCR assay. DNA from all vertebrate species was detected in at least four of five study nymphs at seven and 14 days post-feeding. DNA of humans, domestic dogs, guinea pigs, pigs, and chickens were more successfully detected (80-100%) through day 21, and less successfully (20-100%) at day 28. Findings demonstrate that species-specific PCRs can consistently identify feeding sources of T. infestans within two weeks, a biologically relevant time interval.