Rubella-Related PH Leads to Infant Mortalities

Pulmonary hypertension can be a devastating disease, especially when it impacts infants and children. A new study in Pediatrics from Nagasaki University and Nagasaki University Hospital in Japan and Khanh Hoa General Hospital and Health Service in Vietnam found high rates of mortality from pulmonary hypertension in infants with congenital rubella syndrome.

Although some countries, including the United States, have rubella vaccines as part of their national immunization program, many do not, and this leaves their populations susceptible to infection during large-scale outbreaks such as the one in 2011. The study at hand, led by Michiko Toizumi, MD, and Lay-Myint Yoshida, MD, PhD, conducted a prospective surveillance study from October 2011 to September 2012 of 38 infants (<12 months old) predicted to have congenital rubella syndrome.

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During the outbreak, 7.8 cases of congenital rubella syndrome presented for every 1,000 live births in November 2011. Looking at a wider time frame, 2.1 cases per 1,000 live births presented from July 2011 to June 2012. The investigators estimated it was around this time, between November 2010 and September 2011, that mothers of the infants became pregnant. Eighty-six percent of the mothers had fever and rashes during their first trimester of pregnancy, suggestive of rubella infection.

After following the infants to January 2013, the investigators noted 13 infants had died. Pulmonary hypertension was the most prominent cause of death due to patent ductus arteriosus (PDA). According to the National Institutes of Health, PDA results in abnormal blood flow between the aorta and pulmonary artery and causes oxygenated blood and deoxygenated blood to mix. As explained by the Mayo Clinic, rubella infection can spread from a mother across the placenta to her child and damage the blood vessels, heart, and other organs, leading to PDA.

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At the initial screening, 72% of infants had cardiovascular defects, and the most common of these was PDA. Among the other health issues were hearing impairment (93%), purpura (84%), thrombocytopenia (76%), low birth weight (71%), hepatosplenomegaly (68%), and cataracts (13%).

To combat these pulmonary hypertension-related deaths in the future, the researchers believe timely intervention for cardiovascular defects is crucial for congenital rubella sydrome patients. Echocardiography, used in this study for initial assessments, is a powerful diagnostic and prognostic tool for this purpose. Importantly, it can be employed in developing countries, where it is most likely rubella vaccination is not common.