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The Division of Infectious Disease has had two main goals. The first is to provide infectious disease consultations to the patients admitted to the UI Children’s Hospital, and to staff an outpatient clinic. The second is to maintain an NIH-funded research laboratory, which investigates infectious diseases and vaccines of children. The main research emphasis has been varicella-zoster virus (VZV), the virus infection, which causes varicella (chickenpox) in children and herpes zoster (shingles) in adults. In 1995, a live attenuated varicella vaccine was approved by the FDA and that vaccine is now administered to all children in the United States. A zoster vaccine was approved in 2006 and that vaccine is now recommended for all adults who are 60 years of age and older.
The clinical service includes both inpatient and outpatient activities. The pediatric infectious disease clinic is held one-half day per week. However, in emergent situations, special arrangements can be made to schedule a patient more quickly. Typical diseases followed in the pediatric infectious disease clinic include recurrent Staphylococcal infections (such as MRSA), streptococcal disease, Salmonella infections, community-acquired pneumonia, urinary tract infections, as well as bone and joint infections. Chronic viral infections include recurrent herpes simplex and cytomegalovirus infections, as well as HIV infection. Recently, there have been an increasing number of clinic visits for management of Lyme Disease (Borrelia) and histoplasmosis in Iowa children.
The pediatric infectious disease faculty also provide consultations for hospitalized children. Many of these consults are requested by the pediatric intensive care unit, as well as the surgical subspecialty services, such as orthopedics and neurosurgery. Children with acute infectious disease problems that do not require intensive care are admitted to the general pediatric inpatient service, which is staffed by hospitalists. If desired, the pediatric infectious disease faculty can arrange for the transfer of a child with an acute infectious disease problem from an outside hospital to the University of Iowa Children’s Hospital.
The Division Infectious Disease has received NIH grant funding over the past decades to study varicella-zoster virus (VZV). The studies have included several aspects of structural and cellular biology relating to VZV infection. The major constituents of the VZV envelope have been defined. Other investigations have involved the role of autophagy in VZV infection. Several collaborative studies have been performed with the National Microbiology Laboratory of Canada. These studies led to the complete genomic sequencing of 18 VZV strains. The size of the VZV genome is 125 kbp.
Phylogenetic analysis of the sequenced genomes has led to an extensive table of single nucleotide polymorphisms found within VZV genomes. In turn, enumeration of these polymorphisms has led to the discovery that most VZV strains can be segregated into clades based on their geographical origins. Based on these phylogenetic analyses, we can predict that the ancestral varicella genome arose around 60-70 million years ago.
Additional collaborative studies with investigators in Japan have concentrated on the differences between the vaccine and wild type VZV strains. Currently varicella vaccine is administered to all young children in the United States and Canada. Yet there is no explanation for the attenuation of the varicella vaccine. Recent studies have defined a single nucleotide polymorphism in a small gene as one likely candidate mutation, which causes attenuation in the vaccine. Since the VZV genome has 70 genes, it is likely that mutations within several genes lead to the attenuation phenotype.