Vector-host interactions and epizootiology of eastern equine encephalitis virus in Massachusetts.

Eastern equine encephalitis (EEE) virus is a highly pathogenic mosquito-borne zoonosis that is responsible for outbreaks of severe disease in humans and equines, resulting in high mortality or severe neurological impairment in most survivors. In the northeastern United States, EEE virus is maintained in an enzootic cycle involving the ornithophilic mosquito, Culiseta melanura (Coquillett) and passerine birds in freshwater swamp habitats. To evaluate the role of Cs. melanura and Culiseta morsitans (Theobald) in recent episodes of EEE virus activity in Massachusetts, we collected blood-fed mosquitoes between June, 2007, and October, 2008, from virus foci in 6 counties, and identified the source of blood meals by PCR amplification of mitochondrial cytochrome b gene and sequencing. Analysis of 529 Cs. melanura and 25 Cs. morsitans revealed that nearly 99% and 96% of mosquitoes, respectively, acquired blood meals solely from avian hosts. American Robin, Turdus migratorius Linnaeus was identified as the most common vertebrate host for Cs. melanura (21.7%, n=115), followed by Tufted Titmouse, Baeolophus bicolor (L.) (8.7%, n=46), Black-capped Chickadee, Poecile atricapillus (L.) (8.5%, n=45), Scarlet Tanager, Piranga olivacea (Gmelin) (6.8%, n=36), Field Sparrow, Spizella pusilla (Wilson) (6.2%, n=33), Northern Cardinal, Cardinalis cardinalis (L.) (5.7%, n=30), and other mostly Passeriformes birds. Mammalian-derived blood meals were identified as white-tailed deer, Odocoileus virginianus Zimmermann, domestic cow, Bos taurus L., and human, Homo sapiens L. There were 4 isolations of EEE virus, West Nile virus, and Highland J virus from Cs. melanura. Our results in conjunction with other lines of evidence, including reservoir competency, prevalence of antibody, and infection in nature, suggest that the American Robin, Tufted Titmouse, Black-capped Chickadee, and a few other passerine birds may play key roles in supporting EEE virus transmission in Massachusetts. Infrequent blood feeding of Cs. melanura on mammalian hosts, including humans, also indicates that this mosquito may occasionally contribute to epidemic/epizootic transmission of EEE virus in this region.

Percutaneously placed central venous catheter-related sepsis in Canadian neonatal intensive care units.

OBJECTIVES: To estimate daily risk, variability between centers, and impact on outcomes of catheter-related sepsis (CRS) among preterm neonates. STUDY DESIGN: Retrospective evaluation of data from centers in the Canadian Neonatal Network for neonates born at <29 weeks or <1000 g who had a percutaneously placed central venous catheter (PCVC) in place for ≥ 48 hours. RESULTS: Of 2966 infants with a PCVC, 582 (19.6%) developed CRS (overall rate 11/1000 catheter days). The daily risk of CRS varied between 1% and 2% in the first 28 days, and rates of CRS varied between centers (0 to 37 infections/1000 catheter days). Birth weight and gestational age were lower, and Score for Neonatal Acute Physiology and day of life of insertion were higher among those with CRS. Average length of stay was 6.2 days longer for those with CRS. There was no difference in mortality or major morbidities between infants who had CRS and those without CRS. CONCLUSIONS: No threshold length of catheter usage days within the first 28 days was identified at or after which the risk of CRS increased. Marked variability between centers was present. Patients with CRS had an increased length of stay, but no increased risk for mortality or major morbidities.

Two hour blood glucose levels in at-risk babies: An audit of Canadian guidelines.

BACKGROUND: The Canadian guidelines recommend blood glucose (BG) screening starting at 2 h of age in asymptomatic 'at-risk' babies (including small-for-gestational-age [SGA] and large-for-gestational-age [LGA] infants), with intervention cut-offs of 1.8 mmol/L and 2.6 mmol/L. The present study reviews and audits this practice in full-term newborn populations. METHODS: A literature review meta-analyzed BG values in appropriate-for-gestational age (AGA) term newborns to establish normal 1 h, 2 h and 3 h values. A clinical review audited screening of 'at-risk' SGA and LGA term newborns, evaluating both clinical burden and validity. RESULTS: The review included six studies, although none clearly defined the plasma glucose standard. The pooled mean (plasma) BG level in AGA babies 2 h of age was 3.35 mmol/L (SD=0.77), significantly higher than 1 h levels (3.01 mmol/L, SD=0.96). In the audit, 78 SGA and 142 LGA babies each had an average of 6.0 and 4.7 BG tests, respectively. The mean 2 h BG levels for SGA (3.42 mmol/L, SD=1.02) and LGA (3.31 mmol/L, SD=0.66) babies did not differ significantly from the AGA pooled mean. Receiver operating characteristic curves showed that 2 h BG levels in LGA and SGA babies predicted later hypoglycemia (defined as a BG level lower than 2.6 mmol/L), but sensitivities and specificities were poor. CONCLUSIONS: Published 2 h BG levels for AGA babies are higher than 1 h values and are similar to audited 2 h levels in SGA and LGA babies. Clinically, 2 h levels are predictive of later hypoglycemia but may require repeat BG testing. Audit is an important tool to validate national guidelines, to minimize their burden and to maximize their utility.

Ante- and intra-partum factors that predict increased need for neonatal resuscitation.

BACKGROUND: In the absence of identified risk factors, 7% of term newly borns require PPV-ETT (positive pressure ventilation and/or endotracheal intubation). Factors increasing need for resuscitation, and therefore for individuals with advanced resuscitation skills, require further evaluation. OBJECTIVE: To evaluate the predictive value of ante- and intra-partum risk factors for PPV-ETT in "at-risk" deliveries. DESIGN/METHODS: Over a 30-month period, the neonatal resuscitation team (NRT) at the tertiary perinatal centre in St. Johns, Newfoundland and Labrador, prospectively recorded reasons for attending "at-risk" deliveries, and subsequent use of PPV-ETT, rates of low 1- and 5-min Apgar scores, and admission to neonatal intensive care or death. RESULTS: Of 5691 deliveries, 3796 (66.7%) were attended by the NRT. Data were available for 3564 (94%) at-risk attendances, of which 780 (22%) required PPV-ETT. Using multivariate logistic regression analysis, significant ante-partum risk factors for PPV-ETT included multiple pregnancy <35 weeks, maternal infection, hypertension, and oligohydramnios; intra-partum factors were preterm delivery at <36 weeks, breech presentation, meconium-stained amniotic fluid (MSAF), non-reassuring fetal heart rate, emergency Caesarean section (EmCS), shoulder dystocia, and opiates in normal labour. Elective Caesarean section (ElCS) was protective. Forceps, vacuum, and regional or general anaesthesia did not increase risk. EmCS and preterm birth predicted PPV-ETT, low Apgar scores, and admission to neonatal intensive care (or death), and along with MSAF, made up the majority of "at-risk" babies. CONCLUSIONS: Given the baseline risk (22%), factors that increase need for resuscitation in a tertiary centre may not alter the practice of the NRT attending all "at-risk" deliveries, with the exception of ElCS.

Iron absorption and oxidant stress during erythropoietin therapy in very low birth weight premature infants: a cohort study.

BACKGROUND: Iron supplementation may be associated with oxidative stress particularly in premature infants. Our purpose was to examine 1) early supplemental iron during treatment with erythropoietin (EPO) and oxidative stress; 2) enhanced iron absorption during EPO in those infants receiving human milk. Therefore, we determined the effect of erythropoietin plus supplemental iron intakes (4 mg/kg/d) on antioxidant status and iron incorporation. METHODS: Ten very-low-birth-weight infants who were enterally fed and receiving either human milk or formula were followed for 4 weeks during erythropoietin therapy; blood and urine were collected at 3 times; baseline, 2 and 4 weeks later. Once oral feeds commenced the study protocol was initiated. After baseline blood collection, a dose of Fe57 was administered. Two weeks later, a dose of Fe58 was administered as ferrous chloride to determine the effect of human-milk or formula on iron incorporation into RBCs. RESULTS: Infants started the study at 35 +/- 13 days. Incorporation of isotope into RBCs did not differ between formula fed for Fe57 (mean incorporation 8 +/- 2.9 n = 3) compared to human-milk fed infants (8.7 +/- 5 n = 7) nor for Fe58 (6 +/- 2.7 n = 3 vs. 8.6 +/- 5 n = 7). Tissue damage measured by malondialdehyde in plasma and F-2--isoprostanes in urine, did not differ by feed or over time. Neither ability to resist oxidative stress/nor RBC superoxide dismutase differed according to feed or over time. CONCLUSION: Data suggest that during erythropoietin therapy antioxidant defence in VLBW infants are capable of dealing with early supplemental iron during treatment with EPO.

Variations in rates of nosocomial infection among Canadian neonatal intensive care units may be practice-related.

BACKGROUND: Nosocomial infection (NI), particularly with positive blood or cerebrospinal fluid bacterial cultures, is a major cause of morbidity in neonatal intensive care units (NICUs). Rates of NI appear to vary substantially between NICUs. The aim of this study was to determine risk factors for NI, as well as the risk-adjusted variations in NI rates among Canadian NICUs. METHODS: From January 1996 to October 1997, data on demographics, intervention, illness severity and NI rates were submitted from 17 Canadian NICUs. Infants admitted at < 4 days of age were included. NI was defined as a positive blood or cerebrospinal fluid culture after > 48 hrs in hospital. RESULTS: 765 (23.5%) of 3253 infants < 1500 g and 328 (2.5%) of 13228 infants > or = 1500 g developed at least one episode of NI. Over 95% of episodes were due to nosocomial bacteremia. Major morbidity was more common amongst those with NI versus those without. Mortality was more strongly associated with NI versus those without for infants > or = 1500 g, but not for infants < 1500 g. Multiple logistic regression analysis showed that for infants < 1500 g, risk factors for NI included gestation < 29 weeks, outborn status, increased acuity on day 1, mechanical ventilation and parenteral nutrition. When NICUs were compared for babies < 1500 g, the odds ratios for NI ranged from 0.2 (95% confidence interval [CI] 0.1 to 0.4) to 8.6 (95% CI 4.1 to 18.2) when compared to a reference site. This trend persisted after adjustment for risk factors, and was also found in larger babies. CONCLUSION: Rates of nosocomial infection in Canadian NICUs vary considerably, even after adjustment for known risk factors. The implication is that this variation is due to differences in clinical practices and therefore may be amenable to interventions that alter practice.

The development and implementation of a multidisciplinary neonatal resuscitation team in a Canadian perinatal centre.

PURPOSE: To describe the implementation of a multidisciplinary neonatal resuscitation team (NRT) at a Canadian tertiary perinatal centre. METHODS: In February 2002, the primary role of neonatal resuscitation was transferred from attending physicians (on-call off-site) to a NRT (consisting of a neonatal intensive care nurse, a respiratory therapist, and, when available, a resident, clinical associate (supervised licensed physician), or nurse practitioner). The NRT attended moderate- and high-risk deliveries (in the latter case, accompanied by a neonatologist). Normal, low-risk deliveries remained the responsibility of caseroom (delivery room) staff, assisted by the NRT when concerns arose. A prospective assessment was performed of resuscitation requirements and outcomes. RESULTS: : Over 24 months, the NRT attended 2944 (64.5%) out of 4565 deliveries. The NRT attended 2497 moderate-risk deliveries, providing positive pressure ventilation (in 15.7% of cases), chest compressions (0.1%), and epinephrine (adrenaline) (0.08%). There were no neonatal deaths or morbidities related to resuscitation in this cohort. A small, but significant, proportion of babies with no identifiable risk factors required resuscitation by caseroom staff (in most cases with brief periods of positive pressure ventilation). CONCLUSION: Assignment of level of risk provides a safe means of delivering neonatal resuscitation services, facilitating NRT attendance at the majority of deliveries that required resuscitation. A NRT can perform safely and effectively in a tertiary perinatal centre with off-site support from experienced neonatal staff at high-risk deliveries only. Caseroom (delivery room) staff should continue to be trained in neonatal resuscitation.

A double-masked, randomized control trial of iron supplementation in early infancy in healthy term breast-fed infants.

OBJECTIVES: To test whether iron supplementation affects hematologic, biochemical, and developmental status in term breast-fed infants. STUDY DESIGN: Term breast-fed infants (n=77) were randomly selected to receive either 7.5 mg per day of elemental iron as ferrous sulfate or placebo from 1 to 6 months of age. Investigators and families were unaware of group assignment. Complete blood count and ferritin, red cell superoxide dismutase, catalase, plasma ferric reducing antioxidant power, and zinc and copper levels were analyzed at 1, 3.5, 6, and 12 months of age. Bayley mental and psychomotor developmental indexes (MDI and PDI) and visual acuity (with the use of Teller acuity cards) were assessed from 12 to 18 months of age. Analysis performed by analysis of variance and t tests was by intention to treat. RESULTS: Iron supplementation resulted in higher hemoglobin and mean corpuscular volume at 6 months of age and significantly higher visual acuity and PDI at 13 months of age (100+/-12 vs 93+/-9 [+/-SD]). Treatment and placebo groups did not differ in anthropometric indexes, compliance, biochemical status, or demographic characteristics. CONCLUSIONS: Iron supplementation of breast-fed infants appears safe and might have beneficial hematologic and developmental effects for some infants.

Higher mortality rates among inborn infants admitted to neonatal intensive care units at night.

OBJECTIVE: To examine circadian variation in deaths among infants < or =32 weeks' gestation admitted to Canadian neonatal intensive care units (NICU). STUDY DESIGN: We examined all infants (n=5192) between 24 and 32 weeks' gestation with complete data, who were admitted to 17 tertiary Canadian Neonatal Network NICUs from January 1996 to October 1997. Multivariable logistic regression was used to compare risk-adjusted early neonatal mortality rates (death within 7 days of NICU admission) of infants admitted during daytime (8 am to 5 pm) with infants admitted at night. RESULTS: Sixty percent (n=3131) of infants were admitted to the NICU at night. Patient risk factors significantly (P<.05) predictive of early neonatal death from multivariable logistic regression were male sex, outborn status, APGAR score <7 at 5 minutes, presence of congenital anomalies, low gestational age, and high admission Score for neonatal acute physiology, version II (SNAP-II). For inborn infants, in-house presence of a neonatal fellow or attending neonatologist at night (odds ratio, 0.6) and NICU admission at night (odds ratio, 1.6) were also predictive. CONCLUSIONS: Risk-adjusted early neonatal mortality odds was 60% higher among inborn infants < or =32 weeks' gestation admitted to NICUs at night compared with during daytime, equivalent to 29 excess deaths per 1000 infants.

Variations in central venous catheter-related infection risks among Canadian neonatal intensive care units.

BACKGROUND: The objective of this study was to examine central venous catheter (CVC)-related nosocomial blood stream infection risks of umbilical venous, percutaneous and Broviac catheters, as well as variations in CVC use and CVC-related risk for nosocomial blood stream infection in the neonatal intensive care unit (NICU). METHODS: A cohort study was performed based on 19,507 infants admitted to 17 NICUs in the Canadian Neonatal Network from January, 1996, through October, 1997. Information on these subjects was prospectively collected by trained abstractors. Incidence of infection was measured as infection episodes per 1000 patient days. The risk ratio (RR) of CVC use for nosocomial blood stream infection was calculated as the infection rate during catheter days divided by the infection rate during noncatheter days. Using a Poisson regression model we examined the adjusted RR of CVC use for nosocomial blood stream infection, controlling for patient characteristics and illness severity at admission. Interinstitutional variations in CVC-related infection risks were examined by stratified analyses. RESULTS: CVC were used in 22.5% of patients. The incidence of nosocomial blood stream infection was 2.9 per 1000 noncatheter days, 7.2 per 1000 umbilical venous catheter days, 13.1 per 1000 percutaneous catheter days and 12.1 per 1000 Broviac catheter days. The RR for nosocomial blood stream infection, adjusted for differences in patient characteristics and admission illness severity, was 2.5 for umbilical venous catheter, 4.6 for percutaneous catheter and 4.3 for Broviac catheter (P < 0.05). There were significant (P < 0.05) risk-adjusted variations in CVC-related infection risks among NICUs. CONCLUSIONS: CVC use increased the risk of nosocomial blood stream infection. The risk of nosocomial blood stream infection in percutaneous and Broviac catheters was 70 to 80% higher than in umbilical venous catheters. There was significant variation in CVC-related infection risks among Canadian NICUs.