The incidence, characteristics, and presentation of dengue virus infections during infancy

Abstract

Infants are a vulnerable and unique population at risk for dengue in endemic areas. This report describes the incidence and presenting clinical features of infant dengue virus (DENV) infections from a prospective community-based study performed between January 2007 and May 2009 in the Philippines. DENV3 was the predominant infecting serotype over a wide spectrum of disease severity, ranging from inapparent infection to dengue hemorrhagic fever (DHF). In 2007, the incidence of inapparent DENV infections during infancy was 103 per 1,000 persons person-years and 6-fold higher than symptomatic dengue. The age-specific incidence of infant DHF was 0.5 per 1,000 persons over the age of 3-8 months, and it disappeared by age 9 months. A febrile seizure, macular rash, petechiae, and lower platelet count were presenting clinical features associated with DENV infection among infants with acute undifferentiated febrile illnesses. Community-based studies can help to delineate the incidence rates, disease spectrum, and clinical features of DENV infections during infancy.

Figure 1.

(A) Age-specific incidence of symptomatic DENV infections in infants. Black filled bars, hospitalized DHF; gray filled bars, hospitalized DF; open bars, mild outpatient dengue illness. (B) Age distribution of infants with symptomatic DENV infections. Black filled bars, number of hospitalized infants with DHF; open bars, number of symptomatic infants without DHF (hospitalized and non-hospitalized).

Figure 2.

DENV IgM ELISA results from acute illness and convalescent phase sera for infants with symptomatic primary DENV infections (N = 80 serum samples). The number of samples with positive or negative DENV IgM levels is shown versus the number of days after illness onset when the samples were collected. Black filled bars, sera with DENV IgM ELISA values above the positive threshold value (DENV IgM positive); gray filled bars, sera with DENV IgM ELISA values below the positive threshold value (DENV IgM negative).