Pediatric HIV Infection and Decreased Prevalence of OPV Point Mutations Linked to Vaccine-associated Paralytic Poliomyelitis.

Background: Mutations associated with prolonged replication of the attenuated polioviruses found in oral poliovirus vaccine (OPV) can lead to vaccine-derived poliovirus (VDPV) and cause paralysis indistinguishable from that caused by wild poliovirus. In response, the World Health Organization has initiated the transition to exclusive use of inactivated poliovirus vaccine (IPV), with OPV administration in cases of outbreak. However, it is currently unclear how IPV-only vaccination, well known to provide humoral but not mucosal immunity, will impact the development of paralysis causing OPV variants. Children infected with human immunodeficiency virus (HIV) have been documented to show decreased mucosal immunity following OPV vaccination. Thus, HIV-infected children vaccinated with OPV may serve as proxy for children with IPV-only vaccination. Methods: We conducted a prospective study of Zimbabwean infants receiving OPV as part of their routine vaccination schedule. Stool samples collected from OPV-vaccinated children serially until age 24 months were tested for OPV serotypes using a real-time polymerase chain reaction protocol that quantifies the amount of mutant OPV variants found in each sample. Results: Out of 2130 stool samples collected from 402 infants 365 stool samples were OPV positive: 313 from 212 HIV-noninfected (HIV-) infants and 52 from 34 HIV-infected (HIV+) infants. HIV- infants showed significantly higher proportions of OPV mutants when compared to HIV+ infants. Conclusions: HIV infection is associated with a reduced proportion of OPV vaccine associated paralytic polio mutants. These results suggest that OPV administered to individuals previously vaccinated only with IPV will show decreased propensity for OPV mutations.

Lab Protocol Paper: Use of a High-throughput, Multiplex Reverse-transcription Quantitative Polymerase Chain Reaction Assay for Detection of Sabin Oral Polio Vaccine in Fecal Samples.

Background: Global polio eradication efforts rely in part on molecular methods of detecting polioviruses, both wild and vaccine strains, from human and environmental samples. Previous assays used for detection of Sabin oral polio vaccine (OPV) in fecal samples have been labor and time intensive and vary in their sensitivity and specificity. Methods: We developed a high-throughput, multiplex reverse-transcription quantitative polymerase chain reaction assay able to detect all 3 OPV strains in fecal samples. The assay used a KingFisher Duo Prime system for viral RNA isolation and extraction. Positive samples were retested and Sanger sequenced for verification of Sabin serotype identity. Results: The 95% lower limit of detection was determined to be 3 copies per reaction for Sabin 1 and 3 and 4 copies per reaction for Sabin 2, with no cross-reactivity between the 3 serotypes and their primers. A total of 554 samples (3.6%) were positive, with 304 positive samples (54.9%) containing >1 serotype. Of the positive samples, 476 (85.9%) contained enough RNA to be sequenced, and of these all sequences were Sabin serotypes. The previous assay we used could process 48 samples in a 10-hour period, whereas the new assay processed >100 samples in 6 hours. Conclusions: The new high-throughput, multiplex reverse-transcription quantitative polymerase chain reaction assay allowed for sensitive and specific detection of OPV serotypes while greatly decreasing sample handling and processing time. We were able to sequence 72.4% of the 210 positive samples in the cycle threshold range of 35-37.

Vaccine poliovirus shedding and immune response to oral polio vaccine in HIV-infected and -uninfected Zimbabwean infants.

BACKGROUND: With prolonged replication, attenuated polioviruses used in oral polio vaccine (OPV) can mutate into vaccine-derived poliovirus (VDPV) and cause poliomyelitis outbreaks. Individuals with primary humoral immunodeficiencies can become chronically infected with vaccine poliovirus, allowing it to mutate into immunodeficiency-associated VDPV (iVDPV). It is unclear if children perinatally infected with the human immunodeficiency virus (HIV), who have humoral as well as cellular immunodeficiencies, might be sources of iVDPV. METHODS: We conducted a prospective study collecting stool and blood samples at multiple time points from Zimbabwean infants receiving OPV according to the national schedule. Nucleic acid extracted from stool was analyzed by real-time polymerase chain reaction for OPV serotypes. RESULTS: We analyzed 825 stool samples: 285 samples from 92 HIV-infected children and 540 from 251 HIV-uninfected children. Poliovirus shedding was similar after 0-2 OPV doses but significantly higher in the HIV-infected versus uninfected children after ≥ 3 OPV doses, particularly within 42 days of an OPV dose, independent of seroconversion status. HIV infection was not associated with prolonged or persistent poliovirus shedding. HIV infection was associated with significantly lower polio seroconversion rates. CONCLUSIONS: HIV infection is associated with decreased mucosal and humoral immune responses to OPV but not the prolonged viral shedding required to form iVDPV.

Staphylococcal infections in children, California, USA, 1985-2009.

We conducted a retrospective, observational, population-based study to investigate the effect of staphylococcal infections on the hospitalization of children in California during 1985-2009. Hospitalized children with staphylococcal infections were identified through the California Office of Statewide Health Planning and Development discharge database. Infections were categorized as community onset, community onset health care-associated, or hospital onset. Infection incidence was calculated relative to all children and to those hospitalized in acute-care facilities. A total of 140,265 records were analyzed. Overall incidence increased from 49/100,000 population in 1985 to a peak of 83/100,000 in 2006 and dropped to 73/100,000 in 2009. Staphylococcal infections were associated with longer hospital stays and higher risk for death relative to all-cause hospitalizations of children. The number of methicillin-resistant Staphylococcus aureus infections increased, and the number of methicillin-susceptible S. aureus infections remained unchanged. Children <3 years of age, Blacks, and those without private insurance were at higher risk for hospitalization.

Trends in hospitalization for pediatric pyelonephritis: a population based study of California from 1985 to 2006.

PURPOSE: We examined trends in pediatric hospitalization for pyelonephritis from 1985 to 2006 and identified factors associated with admission. MATERIALS AND METHODS: We performed a population based analysis of hospital discharges using the Office of Statewide Health Planning and Development database to evaluate trends in California regarding pediatric hospitalizations for pyelonephritis from 1985 to 2006. Multivariable logistic regression was performed to identify factors associated with admission for pyelonephritis. RESULTS: A total of 46,300 children were hospitalized for pyelonephritis in California from 1985 to 2006. The overall rate of hospitalization for pyelonephritis increased by greater than 80%, from 17 per 100,000 children in the California population in 1985 to 31 per 100,000 in 2005. This change was primarily due to the nearly ninefold increase in pyelonephritis hospitalizations observed in children younger than 1 year, from 28 per 100,000 in 1985 to 238 per 100,000 in 2005. Among children younger than 1 year males without private insurance and of nonwhite race had increased odds of hospitalization, while females with private insurance and of Asian race had increased odds of hospitalization, compared with nonprivate insurance and white race, respectively. CONCLUSIONS: A significant increase in hospital admissions for pyelonephritis, primarily in children younger than 1 year, occurred in California between 1985 and 2006. Further studies are needed to establish the cause of this striking increase and to determine why certain pediatric populations are at increased risk for hospitalization.

Shedding of Oral Poliovirus Vaccine (OPV) by HIV-Infected and -Uninfected Mothers of OPV-Vaccinated Zimbabwean Infants.

Community circulation of oral poliovirus vaccine (OPV) likely begins with household transmission. We analyzed stool collected from Zimbabwean mothers who were infected with human immunodeficiency virus (HIV) and those who were uninfected with HIV 1 to 24 weeks after infant oral poliovirus vaccination. Overall, only 5% of the mothers had detectable OPV (16 of 304) despite high infant shedding rates. OPV shedding was similar between HIV-infected mothers and those who were uninfected (11 [6.4%] of 171 vs 5 [3.8%] of 133, respectively) and between mothers of HIV-infected infants and those of uninfected infants (2 [3.5%] of 57 vs 9 [6.3%] of 144, respectively). Mothers of vaccinated infants are unlikely to shed OPV, even when they are infected with HIV.

Temporal trends in early clinical manifestations of perinatal HIV infection in a population-based cohort.

CONTEXT: The effect of early antiretroviral therapy (ART) on the early progression of perinatal human immunodeficiency virus (HIV) infection is not well defined. OBJECTIVE: To examine early disease progression and survival in a population-based cohort with perinatal HIV infection in relation to year of birth and use of ART. DESIGN, SETTING, AND PATIENTS: Retrospective study of temporal trends in early progression of perinatal HIV infection among 205 HIV-infected children in Northern California born between January 1, 1988, and December 31, 2001, and followed up through age 3 years. MAIN OUTCOME MEASURES: Prevalence of and age at progression to a first US Centers for Disease Control and Prevention category C diagnosis relative to year of birth, type of ART, and age at initiation of therapy. RESULTS: Of 205 children, 134 (65%) received ART and/or Pneumocystis jiroveci pneumonia prophylaxis. By age 3 years, 81 (40%) progressed to a category C diagnosis, 41 (51%) of whom died. Untreated children were significantly more likely to progress to a category C diagnosis (62% [44/71] untreated vs 28% [37/134] treated children, P<.001); none of 23 infants who received triple ART progressed to category C. However, even without triple ART, very early mono/dual ART (by age 2 months vs 3-4 months) was associated with delayed and decreased progression to category C (P = .02). Of 33 children born between January 1, 1996, and December 31, 2001, only 7 (21%) progressed to category C (P = .02 compared with 1988-1995), 6 of 7 of whom received no therapy. More recent year of birth and more advanced therapy were associated with improved survival. CONCLUSIONS: This population-based cohort demonstrated decreased early HIV progression and improved survival at age 3 years, associated with more advanced therapy. Although limited by small sample size, the findings suggest that very early treatment, even without triple ART, was associated with improved outcome.

Trends in Hospitalizations for Intussusception in California in Relationship to the Introduction of New Rotavirus Vaccines, 1985-2010.

BACKGROUND: The new rotavirus vaccines RV5 and RV1 have been associated with small increase in intussusception risk in active vaccine surveillance studies. It is unclear what the impact might be on the overall trends of intussusception hospitalizations at a large population basis. METHODS: We conducted an ecological study of hospital discharges of infants with intussusception discharge diagnosis using the California Office of Statewide Health Planning and Development database (1985-2010). We measured incidence rates (IR) of intussusception hospitalizations per 100,000 births within 3 periods (1985-1997; 2000-2005; 2006-2010) related to past, pre-introduction and post-introduction of the new rotavirus vaccines. We estimated slopes of yearly IRs within each period, changes in slopes between periods and IR ratios (IRR) of the mean IRs between periods. We did subgroup analyses for 5 age-subgroups. We also analyzed intussusception hospitalizations of infants who also had a surgical repair and/or radiologic reduction procedure code (restricted cohort). RESULTS: We identified 6241 intussusception hospitalizations; 4696 also had pertinent procedure codes. There was an upward trend in yearly IRs during 2006-2010 (+2 excess cases per 100,000 births per year; P = 0.023); the change in slopes between 2006-2010 and 2000-2005 was +3.2 excess cases per 100,000 births per year (P = 0.052), and the IR in 2006-2010 was 10% higher than in 2000-2005 (IRR: 1.10; 95% confidence intervals: 1.01-1.19). The IRR in 2006-2010 versus 2000-2005 for the 6-14 weeks age-subgroup was 1.90 (95% confidence intervals: 1.33-2.74). In the restricted cohort, trends were similar, though not nominally significant. CONCLUSIONS: We documented at a population-level a small increased risk in intussusception hospitalizations post-introduction of the new rotavirus vaccines.

Timing of antiretroviral therapy initiation and its impact on disease progression in perinatal human immunodeficiency virus-1 infection.

OBJECTIVE: Treatment with highly active antiretroviral therapy (HAART) reduces overall perinatal human immunodeficiency virus (HIV) type 1-related mortality. The effect of timing of HAART initiation on reduction of morbidity is not well defined. We evaluated the association of timing of HAART initiation on progression to moderate or severe disease. METHODS: Retrospective, population-based study of 196 perinatally HIV-infected children followed from birth in northern California from 1988 to 2009. RESULTS: Of 196 children, 58% received HAART and were followed for a median of 6.2 years after HAART initiation. HAART use was associated with improved survival to the age of 5 years: no HAART, 50% versus HAART, 88%; P < 0.0001. However, the advantage of initial HAART over mono or dual therapy transitioning to HAART was small and not statistically significant (P = 0.23). Starting HAART before the development of moderate or severe disease delayed the median age of diagnosis of moderate disease from 0.4 years (interquartile range, [0.3-0.8]) without HAART to 3.0 years ([interquartile range, 1.9-5.8]; P < 0.0001) with HAART. HAART initiation after progression to moderate or severe disease was associated with decreased progression to severe disease or death, respectively (moderate to severe: 8% [3/36] with HAART vs. 84% [70/83] with no HAART, P < 0.0001; severe to death: 9% [6/68] with HAART vs. 73% [49/67] with no HAART, P < 0.0001). CONCLUSIONS: In perinatal HIV infection, HAART is associated with delayed progression and reduced mortality regardless of disease severity at HAART initiation. This finding reinforces US guidelines regarding HAART initiation at >1 year of age if children present with most clinical category B diagnoses, regardless of CD4 measurements or plasma HIV RNA level.

Immunologic response to oral polio vaccine in human immunodeficiency virus-infected and uninfected Zimbabwean children.

BACKGROUND: Poliovirus eradication is dependent on maintaining adequate community-wide levels of serologic protection. Many African countries with conditions that favor continued wild poliovirus propagation also have a high prevalence of pediatric human immunodeficiency virus (HIV) infection. Data are limited regarding the degree of serologic immunity conferred on HIV-infected children after immunization with oral polio vaccine (OPV). METHODS: This was a cross-sectional study correlating HIV infection and neutralizing antibodies against poliovirus serotypes 1, 2, and 3 in 95 Zimbabwean children 2 months to 2 years of age, born to HIV-infected mothers, who received OPV according to the national schedule. RESULTS: HIV-infected children had significantly lower rates of seroconversion to all 3 poliovirus serotypes than HIV-uninfected children (60%, 67%, and 47% vs. 96%, 100%, and 82%, P = 0.001, 0.0003, and 0.015 for serotypes 1, 2, and 3 in HIV-infected and uninfected children, respectively, after ≥3 OPV doses). Among poliovirus seroconverters, HIV-infected children also had significantly lower geometric mean titers against serotypes 1 and 2 than HIV-uninfected children (geometric mean titers: 198 and 317 vs. 1193 and 1056, P = 0.032 and 0.050, for serotypes 1 and 2, respectively, after ≥3 OPV doses). In addition, HIV-infected children had significantly higher levels of total IgG and significantly lower CD4% and mean weight than HIV-uninfected children. Of note, none of the HIV-infected children were receiving antiretroviral therapy, and 71% had a CD4% indicating severe immunodeficiency. CONCLUSIONS: Pediatric HIV infection is associated with a poor serologic response to OPV, which could pose an obstacle to global polio eradication.

Epidemiologic trends in penile anomalies and hypospadias in the state of California, 1985-2006.

PURPOSE: Using statewide data, we evaluated whether the changing incidence of penile anomalies and hypospadias is reflected in the diverse California population of newborn males over the past 20 years. METHODS: Discharge data from all California hospitals, prepared by the OSHPD (Sacramento, CA) was reviewed for the years 1985-2006 for male infant births with an ICD-9 code (752.6) for hypospadias, epispadias or other penile anomalies. Trends were examined by Generalized Estimation Equations for Poisson regression. RESULTS: From 1985 to 2006, the birth incidence of newborn penile anomalies increased in California from 47 to 57 cases per 10,000 newborn discharges, yet the trend for hypospadias alone appears stable from 1997. The rates for penile anomalies in newborns increased 1.4% annually (p < 0.001). All racial/ethnic groups analyzed showed this increase (p < 0.001 for each). During the study period there was a 2% increase per year in plural births (p < 0.001). Interestingly, the rate of change in penile anomaly incidence was greater in males of plural births compared to their singleton cohorts (2% vs 1% annually) (p < 0.001). The birth incidence of cleft palate, another congenital anomaly known to be stable over time, remained unchanged over this period. CONCLUSIONS: From 1985 to 2006 in California the incidence of penile anomalies increased in a statistically significant manner, but the incidence of hypospadias appears stable for the last decade. Our data support the notion that different racial/ethnic groups have distinct incidences of penile anomaly formation and that an association with plural births appears to be present.

Pediatric and neonatal Staphylococcus aureus bacteremia: epidemiology, risk factors, and outcome.

OBJECTIVE: To evaluate the impact of methicillin-resistant Staphylococcus aureus on the prevalence of S. aureus bloodstream infection among children. METHODS: Retrospective analysis of demographic data, risk factors for infection, and clinical outcomes for children (age, less than 18 years) with S. aureus bacteremia hospitalized at a children's hospital during 2001-2006. RESULTS: We identified 164 episodes of S. aureus bacteremia among 151 children. The prevalence of bacteremia due to methicillin-susceptible S. aureus during 2001-2003 was approximately the same as that during 2004-2006 (29 and 30 cases, respectively, per 10,000 hospitalized children [hereafter, "per 10,000 hospitalizations"]), but the prevalence of bacteremia due to methicillin-resistant S. aureus increased from 4 to 11 cases, respectively, per 10,000 hospitalizations (P=.015). A total of 48% of infections involved children who had S. aureus-positive blood cultures less than 3 days after hospital admission. Seventy-four percent of these children had a preexisting comorbidity. When the prevalence of S. aureus bacteremia was stratified by race, sex, or age, neonates hospitalized at birth and Hispanic children had significantly reduced risks of infection. Children younger than 1 year of age (excluding neonates hospitalized at birth) had an increased prevalence of hospital-onset S. aureus bacteremia. There was a disproportionate increase in the risk of S. aureus bacteremia for each additional week of hospitalization among children with hospital-onset S. aureus bacteremia. Children with methicillin-resistant S. aureus bacteremia had a longer hospital stay, were transferred to another facility at a greater rate than they were discharged home, and had a greater mortality rate, compared with children with methicillin-susceptible S. aureus bacteremia. CONCLUSION: This study documents the prevalence of S. aureus bacteremia among children with a high risk for acquiring this infection, and it describes populations of children who are at higher risk for bacteremia due to either methicillin-susceptible or methicillin-resistant S. aureus. Methods to improve prevention of S. aureus bacteremia are needed for children with healthcare-associated risk factors for S. aureus bacteremia.

Disease progression among HIV-infected children who receive perinatal zidovudine prophylaxis.

BACKGROUND: Studies of perinatal HIV infection have reported mixed results regarding the prognosis of HIV-infected infants exposed to perinatal zidovudine prophylaxis (PZP). METHODS: We have followed a population-based cohort of children with perinatal HIV infection to evaluate whether early HIV disease progression was more common among those who received PZP and whether subsequent antiretroviral therapy (ART) was less effective in preventing early disease progression. RESULTS: We identified 73 children with perinatal HIV infection born between 1994 and 2001 with at least 3 years of follow-up and with information concerning PZP administration. Children who received PZP started subsequent ART at an earlier age than those who did not receive PZP (median age at starting treatment: 2 months for PZP vs. 6 months for no PZP; P = 0.0002). PZP was associated with decreased early HIV progression: 21% (7 of 33) of children who received PZP progressed to a category C diagnosis by 3 years compared with 45% (18 of 40) of children who did not receive PZP (P = 0.047). Children who did not receive PZP progressed to a category C diagnosis at a younger age than children who received PZP (median: 4 vs. 11 months; P = 0.061). ART was as effective in preventing early HIV progression in children who received PZP as in children who did not receive PZP. CONCLUSIONS: In our population-based cohort of perinatally HIV-infected children, those who received PZP started ART at a significantly earlier age than those who did not receive PZP and also demonstrated decreased HIV disease progression by the age of 3 years.

Shedding and reversion of oral polio vaccine type 3 in Mexican vaccinees: comparison of mutant analysis by PCR and enzyme cleavage to a real-time PCR assay.

A uracil-to-cytosine mutation at nucleotide position 472 of oral poliovirus vaccine type 3 (OPV3) contributes to the development of vaccine-associated paralytic poliomyelitis (VAPP). To analyze OPV3 shedding patterns, we previously used the multistep method of mutant analysis by PCR and enzyme cleavage (MAPREC). This involves conventional reverse transcription-PCR to detect OPV3, followed by a restriction digest to quantify position 472 reversion. Real-time PCR detects and quantifies nucleic acid as PCR occurs and avoids postreaction processing. The goal of this study was to compare a real-time PCR method to MAPREC. Seventy-three stool samples from Mexican OPV recipients underwent the reverse transcription-PCR step of MAPREC and real-time PCR. Real-time PCR identified 23% more OPV3-positive samples than conventional reverse transcription-PCR. When reversion was compared, the revertant proportion (RP), defined as the percentage of revertants in a sample, differed by < or =10% in 21/25 (84%) samples. The four samples differing by >10% were obtained within 5 days of OPV administration. The real-time PCR assay identified samples with an RP of > or =85% with 94% sensitivity and 86% specificity compared to MAPREC. The mean difference in RP between the two methods was 3.6% (95% confidence interval, -0.3 to 7.5%). Real-time PCR methods reliably detect OPV3, and reversion estimates correlate more consistently with MAPREC when OPV3 reversion rates are high. Detecting VAPP-related mutations by real-time PCR is rapid and efficient and can be useful in monitoring ongoing global polio eradication efforts.

Range of normal neutrophil counts in healthy zimbabwean infants: implications for monitoring antiretroviral drug toxicity.

Mother-to-child HIV prevention trials in sub-Saharan Africa use the US National Institutes of Health Division of AIDS (DAIDS) grading scale to monitor hematologic toxicity. A recent study of nevirapine prophylaxis given for 6 months in breast-feeding Zimbabwean infants reported several cases of relative neutropenia in clinically well infants, raising concerns of drug toxicity. However, the DAIDS tables are based on normal blood counts for white infants, although there is evidence that black African infants may have lower absolute neutrophil counts (ANCs) than white infants. To establish normal hematologic values in black Zimbabwean infants and to quantify the apparent prevalence of relative neutropenia in this population, we evaluated HIV-uninfected healthy infants born to HIV-uninfected women at birth, 10 days, 6 weeks, 3, and 4 months of life. A physical examination and blood count were performed at each visit, and an HIV test was performed at the final visit. The ANC values were graded using the DAIDS table. A total of 145 healthy term infants satisfied the inclusion criteria. The mean ANC values for Zimbabwean infants were less than half of the corresponding standard values at all 5 time points (P < 0.0001). Using the DAIDS table in use at the time that the blood was collected, 57% of these healthy infants had relative neutropenia of any grade at birth, followed by 29% at day 10, 53% at 6 weeks, 32% at 3 months, and 37% at 4 months of life. Our data indicate that relative neutropenia exists in healthy black Zimbabwean infants. The guidelines for identifying toxicity were changed in December 2004. However, even by the new DAIDS tables, 43%, 23%, 24%, 42%, and 43% of these healthy babies had relative neutropenia at the time of the 5 visits. Future HIV prevention and treatment trials in sub-Saharan Africa should use normal hematologic values derived from African infants to avoid the overestimation of antiretroviral drug toxicity.

Shedding of sabin poliovirus Type 3 containing the nucleotide 472 uracil-to-cytosine point mutation after administration of oral poliovirus vaccine.

A uracil-to-cytosine point mutation at nucleotide (nt) 472 of Sabin oral poliovirus vaccine (OPV) type 3 is found in conjunction with vaccine-associated paralytic poliomyelitis (VAPP). Direct RNA extraction and mutant analysis by polymerase chain reaction and restriction enzyme cleavage were used to identify this point mutation in clinical samples. A total of 238 stool samples were obtained from 28 healthy infants for 6 weeks after OPV vaccination. More than 25% of infants shed OPV3 in the week after vaccination, with a decrease on day 6. A second wave of OPV3 shedding occurred beginning the second week after vaccination and was maintained through the end of the study period. During the first week after vaccination, the proportion of nt 472 mutants in the shed OPV3 increased from undetectable to almost 100%. During the second shedding period, the proportion of nt 472 mutants remained close to 100%. These results suggest that selective mutation drives the VAPP-associated nt 472 point mutation for OPV3 in the human gastrointestinal tract.