To the Editors:
Perinatal mumps is infrequent and usually benign.1 Rarely, infants born to mothers infected with mumps within a few weeks of delivery develop severe respiratory distress in the neonatal period.2–4 Review of the literature reveals a single case of pneumonia accompanied by persistent pulmonary hypertension.5 We report here a second case in which these 2 conditions coexisted in a full-term infant born to a mother infected with mumps 2 weeks before delivery.
A female infant was born at 40 weeks of gestation to a 30-year-old G6 P5 female by spontaneous vaginal delivery with Apgar scores of 9 and 9 at 1 and 5 minutes, respectively. The mother's prenatal tests including HIV, hepatitis B surface antigen and VDRL were negative; Rubella was nonimmune, and group B streptococcus culture was not done. Maternal history was significant for exposure to her 2 unimmunized children with mumps and subsequent development of infection herself 2 weeks before delivery. The infant's weight, length and head circumference were all appropriate for gestational age. General examination was normal. The baby was well until day 2, when she developed fever to 101.6°F. Diagnostic workup included white blood cell count of 14,900/mm3 with a normal differential, hemoglobin of 15 g/dL and platelets of 303,000/mm3. Cerebrospinal fluid examination was normal. Despite treatment with intravenous ampicillin and gentamicin for 7 days, the baby remained febrile, but never developed parotid swelling. Mumps IgM antibody titer of the baby's serum was negative (<8 U/mL) and mumps IgG was 1.48 (positive ≥0.50). The mother's titers were not done. Mumps virus RNA from buccal smear was detected by qualitative RT-PCR (Focus Diagnostics, Cypress, CA). On day 4, the infant developed tachypnea and cyanosis and was treated with O2 by nasal cannula. Chest radiograph was normal. Because of progressive respiratory distress, she was intubated and begun on mechanical ventilation the next day. Chest radiograph eventually showed right upper lobe consolidation and diffuse patchy infiltrates. Blood gas on FiO2 0.90 showed pH 7.38, pCO2 42 mm Hg, pO2 50 mm Hg, BE −0.4. Echocardiogram showed pulmonary artery pressure equal to 2 thirds of systemic pressure and right ventricular enlargement consistent with pulmonary hypertension. Repeat antibody titers at 4 weeks showed persistently positive mumps IgG and newly positive IgM of 52 (positive >12) U/mL consistent with recent infection. There was no evidence of endocardial fibroelastosis, parotitis, pancreatic disease, chorioretinitis, or optic atrophy. Mechanical ventilation and inhaled nitric oxide were provided for 19 and 22 days, respectively. Echocardiogram before discharge showed decreased right ventricular dilatation and resolution of pulmonary hypertension. The infant was discharged on day 55 with no pulmonary support.
Transplacental transmission and postnatally acquired neonatal mumps infection are unusual and when they occur are generally mild.6 The onset of symptoms on the second day of life in the current report is entirely consistent with the incubation period of 7 to 23 days for the mumps virus. In addition, infection was confirmed by RT-PCR detection of the presence of viral genetic material in the buccal mucosa and emergence of IgM antimumps antibodies. Despite the generally benign nature of this infection, we report the second patient in the literature with presumed mumps pneumonia accompanied by persistent pulmonary hypertension of the newborn (PPHN).5 PPHN previously reported in association with pneumonias have for the most part been confined to those with bacterial etiologies such as group B Streptococcus. Presumably, bacterial endotoxins induce the release of mediators like thromboxane, endothelin, and tumor necrosis factor that alter pulmonary vascular resistance.7 In this case, there were no risk factors for bacterial infection and the blood culture was negative. While the 2 cases of mumps-associated PPHN were treated with high frequency ventilation, the baby in the current report also received inhaled nitric oxide with a good clinical response. Despite the absence of classic clinical findings like parotitis, aseptic meningitis, hyperamylasemia, and ophthalmologic abnormalities, mumps must be considered in the differential diagnosis for infants with respiratory disease born to mothers with known mumps exposure/infection during late pregnancy. Although the incidence of mumps during pregnancy has sharply declined following the introduction of vaccine, immunity may wane with time. Although the mother in the current report claimed to have received one dose of mumps vaccine, in the past, the absence of rubella immunity makes this unlikely. Despite the latter, she has refused MMR vaccine for herself and her children. Cases like this offer a cautionary tale on the potential for life-threatening complications like pneumonia and PPHN when vaccines are withheld.
Shashi Sahdev, MD
Philip Roth, MD, PhD
Sylvia Elisabeth Arroyo, MD
Division of Neonatology
Department of Pediatrics
Staten Island University Hospital
Staten Island, NY
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