Perinatal Pandemic (H1N1) 2009 Infection, Thailand

To the Editor: Infection with infl uenza A pandemic (H1N1) 2009 has been reported worldwide following initial identifi cation of the virus in April 2009 (1). The groups at highest risk for infection or infl uenza-related complications include pregnant women and children (2). We report a case of pandemic (H1N1) 2009 infection in a newborn whose mother became ill with pandemic (H1N1) 2009 during the perinatal period. A newborn girl showed signs of respiratory distress. The relevant perinatal history was maternal illness with pandemic (H1N1) 2009 7 days before delivery. The infant, who had a birth weight of 1,560 grams, was delivered by emergency cesarean section after the mother experienced cardiopulmo-nary failure at the gestational age of 31 weeks. Apgar scores were 9 and 9 at 1 and 5 minutes, respectively. Physical examination at birth showed a premature infant girl with mild sub-costal retraction. Oxygen saturation at room air was 91%–99%. Other results of the physical examination were un-remarkable. Initial management included routine care for premature infants. On the basis of the perinatal history, a throat swab specimen was collected for pandemic (H1N1) 2009 testing by PCR and oseltamivir, 6 mg, was administered every 12 hours (4 mg/kg/ day). The specimen obtained from the throat swab was positive for pandemic (H1N1) 2009 by real-time PCR. The infant required oxygen supplemen-tation. At day 2 of life, acute renal failure with an elevated plasma crea-tinine level of 1.1 mg/dL developed in the infant. Chest radiograph showed minimal pulmonary infi ltrations. She was started on cefotaxime for suspected sepsis. Oseltamivir dosage was adjusted based on the glomerular fi l-tration rate estimated by the formula of Schwartz et al. (3) of 10.5 mL/ min/1.73m 2 to 3 mg every 12 hours to complete 10 doses (2 mg/kg/day). Infection of the patient was con-fi rmed by real-time reverse transcrip-tion–PCR of the throat swab specimen and by a 4× increase in antibodies against the virus by hemagglutination inhibition test (HI). Antibody titers against pandemic infl uenza (H1N1) 2009 by HI with turkey erythrocytes (4) on days 10, 24, and 42 of life were 10, 160, and 320, respectively (Figure). At day 4 of life, repeated PCR performed on a throat swab specimen was negative for pandemic (H1N1) 2009. Oxygen supplementation was gradually decreased and fi nally discontinued. Her room air oxygen saturation was 95%–98%. Her clinical symptoms gradually improved. Hemoculture was negative after 72 hours. The …