Embarazo como factor de riesgo de hospitalización y muerte en la pandemia por influenza A (H1N1) en Paraguay / Pregnancy as a risk factor for hospitalization and death during influenza A (H1N1) pandemic in Paraguay

La influenza A (H1N1) se ha identificado como la causa de epidemia de Infección Respiratoria Aguda en Paraguay y en el mundo. Se analizaron los factores de riesgo asociados a la morbimortalidad en embarazadas con sospecha de infección por H1N1 notificadas a la Dirección General de Vigilancia de la Salud (DGVS) del MSPBS durante los primeros cuatro meses de la pandemia, en comparación con mujeres en edad fértil no embarazadas con sospecha de infección por H1N1. A partir del 28 de abril de 2009, la DGVS comenzó sistemáticamente la vigilancia de H1N1 en todas sus unidades notificadoras, siendo la notificación inmediata y por planilla individual basándose la notificación en la definición de casos confirmado establecidas por el país. Hasta el 25 de agosto del 2009 fueron notificadas 2268 mujeres con sospecha de H1N1, de las cuales 1120 tenían entre 15 a 40 años, y de ellas 117 estaban embarazadas. El 68% (79/117)de las embarazadas requirió hospitalización y la mortalidad fue de 21% (25/117), mientras que en grupo de las no embarazadas el 21% se hospitalizó (288 /1003) y la mortalidad fue de 1,5% (16/1003). Todos los casos fallecidos desarrollaron Infección Respiratoria Aguda Grave caracterizado por un síndrome de distrés respiratorio que en algunos casos requirieron asistencia respiratoria mecánica (ARM). Ninguna de las embarazadas refirió antecedente de co-morbilidad. El 22% (26/117) de las embarazadas y 2,9% (30/1003) de las no embarazadas recibieron Oseltamivir como tratamiento. Se evidencian que la infección produce alta morbimortalidad en embarazadas en comparación con mujeres del mismo grupo de edad, los cuales apoyan la recomendación de un tratamiento antiviral precoz en gestantes, así como un seguimiento clínico cercano.

Influenza A (H1N1) has been identified as the cause of the Acute Respiratory Infection epidemic in Paraguay and the world. Risk factors associated to morbid-mortality in cases of pregnant women with suspicion of H1N1 infection and notified to the General Direction of Health Surveillance (DGVS in Spanish) of the Ministry of Public Health and Social Welfare (MSPBS in Spanish) during the fourth first months of the pandemic were analyzed in comparison to non-pregnant fertile women with suspicion of H1N1 infection. From April28, 2009 the DGVS started a systematic surveillance of H1N1 in all its notifying units, being the notification immediate and by individual spreadsheet basing the notification inthe case definition established by the country. Until August 25, 2009 2,268 cases of women with suspicion of H1N1 were notified, 1,120 of them were between 15 to 40 years and from them 117 were pregnant. Sixty eight percent (79/117) of the pregnant women required hospitalization and mortality was 21% (25/117) while in the non-pregnant women, 21% were hospitalized (288 /1003) and mortality was 1.5% (16/1003). All deceased cases developed Serious Acute Respiratory Infection characterized by a respiratory distress syndrome that, in some cases, required mechanical respiratory assistance (MRA). None of the regnant women referred history of co-morbidity. Twenty two percent (26/117) of the pregnant women and 2.9% (30/1003) of the non-pregnant women received Oseltamivir as treatment. These results show that the infection produces high morbid-mortality in pregnant women in comparison to women of the same age group, supporting the recommendation of an early antiviral treatment in pregnant women as well as a close clinical follow-up.

Combined effects of noise and styrene on hearing: comparison between active and sedentary rats.

In this study, two investigations were carried out with adult Long-Evans rats exposed to increasing concentrations of styrene. In the first experiment, the hearing of rats, which were forced to walk in a special wheel during the exposure, was compared to that of rats which were sleepy in their cage. The active rats were exposed to styrene concentrations ranging from 300 to 600 ppm, whereas the sedentary rats were exposed from 500 to 1000 ppm for 4 weeks, 5 days per week, 6 hours per day. In the second experiment, designed to evaluate the hearing risks at threshold limit values, active rats were exposed either to a noise having a Leq8h of 85 dB (equivalent level of a continuous noise for a typical 8-h workday), or to 400-ppm styrene or to a simultaneous exposure to noise and styrene. In both experiments, auditory function was tested by auditory-evoked potentials from the inferior colliculus and completed by morphological analyses of the organ of Corti. The results of the first experiment showed that the same amount of styrene-induced hearing loss can be obtained by using concentrations approximately 200 ppm lower in active rats than in sedentary rats. The second investigation showed that, in spite of the low-intensity noise and the low-concentration of styrene, there is a clear risk of potentiation of styrene-induced hearing loss by noise. These findings and exposure conditions were discussed and extrapolated with regard to the risk assessment for human beings. The authors propose to decrease the French threshold limit value of styrene for ensuring a high level of protection for human hearing.

Critical period for styrene ototoxicity in the rat.

The current experiments were undertaken to determine whether or not styrene-induced hearing loss in the rat depends more on the existence of a critical period between 14 and 21 weeks of age than on body weight. For these purposes, two experiments were carried out with mature Long-Evans rats. In the first experiment, two groups of 5-month old rats, but having different body weight (slim: 314 g vs. fat: 415 g) were exposed to 700 ppm styrene for 4 consecutive weeks, 5 days per week, 6 hours per day. In the second experiment, two groups of rats having the same weight: 345 g, but different ages (14- vs. 21- week old) were exposed to styrene in strictly identical experimental conditions. Auditory sensitivity was tested by recording evoked potentials from the inferior colliculus. Surface preparations of the organ of Corti were also performed to complete the investigation. At the end of the six week recovery period following the styrene exposure, a 7 dB permanent threshold shift (PTS) was obtained with the same age animals regardless of the body weight. Consequently, weight was not a major factor in styrene-induced hearing loss. Age was a more critical factor in determining higher sensitivity to styrene. Indeed, the three months old group had 23.5 dB PTS, whereas the five months old group had only a 7.7 dB PTS at 16 kHz. Thus, a 15 dB difference of PTS was obtained between the rats having the same weight but different age. While the weight does not play a major role in styrene ototoxicity, there is a critical period whose duration lasts more than three months and for which the susceptibility to styrene is enhanced.

Is the aged rat ear more susceptible to noise or styrene damage than the young ear?

Noise- and styrene-induced hearing and hair cell loss were studied in young (3 months) and aged (24-26 months) Long-Evans rats. The animals were exposed 6 h/d, 5 d/w for 4 weeks to (a) broadband noise centered at 8 kHz (92 or 97dB SPL), or b) styrene (700 ppm). Auditory sensitivity was tested by recording evoked potentials from the inferior colliculus. Histological analyses of the organ of Corti, stria vascularis, and the spiral ganglions were also performed. Aged controls showed outer hair cell (OHC) loss at the basal and apical regions of the organ of Corti, and an increase in pigmentation concomitant to a decrease in vascularization of the stria vascularis, along with elevated thresholds relative to young controls. The 92-dB noise caused similar threshold shifts in both age groups, whereas the 97-dB noise caused more threshold shifts in the aged group compared to the young group. Recovery of the hearing thresholds depended both on the intensity of the noise and on the age of the animals. Aged rats had minimal hair cell loss as a result of styrene exposure, whereas young animals showed significant OHC loss, particularly in third row. Despite significant loss of OHCs, the young subjects showed styrene-induced threshold shifts only at high frequencies. In summary, the data show that : (a) there is an influence of age on both noise-induced and styrene-induced threshold shift and hair cell loss in rats and (b) the cochlea appear to have a redundancy in the number of OHCs, thus threshold shift does not necessarily occur with significant OHC loss.