Illness In Infants Research Articles

The perfusion index of healthy term infants during transition at birth.

Perfusion index is a continuous parameter provided by pulse oximetry and might be useful for evaluating hemodynamic changes at birth and identifying transitional problems. The objective was to describe perfusion index values in term infants immediately after birth. Perfusion index of 71 healthy term born infants were recorded during the first 10 min after birth, using a pulse oximetry sensor placed preductally. A Wilcoxon signed-rank test was used to compare between time points. No significant trend in perfusion index could be observed in term-delivered infants. There was a significant difference between 2 and 3 min (2.4 (1.6–5.0) vs. 2.3 (1.6–3.7), p = 0.05) and between 3 and 4 min after birth (2.3 (1.6–3.7) vs. 2.1 (1.4–3.2), p < 0.001). There was no significant change in median PI values in the following 8 min.Conclusion: Perfusion index does not change significantly during transition at birth in healthy term infants born by normal vaginal delivery or cesarean section. Large variation in perfusion index causes monitoring this parameter to have limited value. What is known: • Perfusion index is a non-invasive indicator for peripheral perfusion.• Perfusion index values <1.24 are seen as an accurate predictor for severity of illness for infants admitted to the neonatal intensive care unit. What is new: • Although significant physiological changes occur during birth, perfusion index remains stable.• Large variation in perfusion index causes monitoring of this value to have limited value as an additional parameter for evaluating transition at birth.

Effect of feeding pattern on infant illness in Chinese cities.

To investigate the effect of different feeding patterns on the occurrence of diseases among infants. Data on socio-economic status, feeding patterns before 6 months (exclusive breast-feeding (EBF); mixed feeding with breast milk and formula (MBF); exclusive formula-feeding (EFF)) and illness of infants were collected via face-to-face interviews. The proportions of infants who had ever been ill or hospitalized and their potential influence factors were investigated. Eight large cities in China. Infants (n 1654) aged 0-11·9 months were recruited from hospitals. For infants aged 0-2·9 months, the percentage who had been ill was 19·2%, 24·1% and 26·3% among the EBF, MBF and EFF groups, respectively. For those aged 3-5·9 and 6-11·9 months, the corresponding percentages were 41·6%, 45·6% and 51·0%, and 67·0%, 73·4% and 67·7%. Respiratory disease was the most common reported illness and cause of hospitalization. The risks of having (total) illness, diarrhoea and respiratory disease increased significantly with age, but not allergic disease. Compared with EBF, MBF and EFF infants had significantly higher risks of having illnesses except for allergic disease, and feeding patterns were not related to hospitalization. Low birth weight, middle family income and low level of mother's education also increased the risk of illness. A protective effect of EBF against total illness in urban Chinese infants was found. An increasing trend with age was observed among the percentages of infants who had been ill or had diarrhoea or respiratory disease, but not allergic disease.

Comparative proteomic analysis of Cronobacter sakazakii isolates with different virulences

Cronobacter is a genus of widespread, opportunistic, foodborne pathogens that can result in serious illnesses in at-risk infants because of their immature immunity and high dependence on powdered formula, which is one of the foods most often contaminated by this pathogen. However, limited information is available regarding the pathogenesis and the specific virulence factors of this species. In this study, the virulences of 42 Cronobacter sakazakii isolates were analyzed by infecting neonatal SD rats. A comparison of the typing patterns of the isolates enabled groups with close relationships but that exhibited distinct pathogenesis to be identified. Among these groups, 2 strains belonging to the same group but showing distinct virulences were selected, and 2-DE was applied to identify differentially expressed proteins, focusing on virulence-related proteins. A total of 111 protein spots were identified using matrix-assisted laser desorption/ionization time-of-flight tandem mass spectrometry (MALDI-TOF/TOF-MS), and 89 were successfully identified. Further analysis suggested that at least 11 of these proteins may be involved in the pathogenesis of this pathogen. Real-time PCR was carried out to further confirm the differential expression pattern of the genes, and the results indicated that the mRNA expression levels were consistent with the protein expression levels. Biological significanceThe virulence factors and pathogenesis of Cronobacter are largely unknown. In combination with animal toxicological experiments and subtyping results of C. sakazakii, comparative proteomics analysis was performed to comprehensively evaluate the differentially expressed proteins of two isolates that exhibited distinct virulence but were closely related. These procedures made it possible to identify the virulence-related of factors of Cronobacter. Among the 89 total identified proteins, at least 11 show virulence-related potential. This work provides comprehensive candidates for the further investigation of the pathogenesis of Cronobacter.

Rhinovirus wheezing illness in infancy is associated with medically attended third year wheezing in low risk infants: results of a healthy birth cohort study.

Rhinoviruses may be pathogens contributing to the development of childhood wheezing. However, their role in low risk infants without an asthmatic predisposition is unknown. Knowing which healthy, low risk children are at increased risk for childhood wheezing after rhinovirus wheezing illness (RV-WI) in infancy, might help in developing prevention and treatment strategies for childhood wheezing. The aim of this study was to determine the association of medically attended wheezing at the age of three with RV-WI in the first year of life in low risk children without parental asthma. In a low risk, prospective birth cohort study, we followed 181 healthy born children from birth through the third year of life. We considered children 'low risk' if neither parent had a doctor's diagnosis of asthma. We determined infant RV-WI by parent-reported wheezing (based on daily logs) and simultaneous molecular rhinovirus detection in the first year of life. Respiratory function and blood eosinophil count were both measured in the first month of life. The primary outcome, third year wheezing, was defined as the use of prescribed inhaled asthma medications together with a doctor's visit for respiratory symptoms in the third year of life. We calculated the association of RV-WI with medically attended third year wheezing and other known possible risk factors for wheezing at the age of three. Among low risk children, third year wheezing was observed in 7 out of 18 (39%) children with versus 10 out of 163 (6%) children without infant RV-WI (OR 9.7, 95% CI 3.1-33.5, P < 0.0001). The association between RV-WI and third year wheezing was unchanged after adjustment for potential confounders such as eosinophilia and atopic eczema. RV-WI is a robust and independent risk factor for third year wheezing in low risk children without parental asthma. Future research will identify and protect those children at increased risk for RV-WI.

Knowledge and attitiudes of pregnant women and their providers towards recommendations for immunization during pregnancy

ObjectivesTetanus, diphtheria and acellular pertussis (Tdap) and influenza vaccination is recommended during each pregnancy but uptake is suboptimal. We evaluated knowledge and acceptance of vaccination recommendations among pregnant women. MethodsProspective, convenience survey of pregnant women presenting for antenatal care at the Pavilion for Women, Texas Children's Hospital, Houston, and their healthcare providers. Results796 of 825 (96.5%) of women and 63 of 87 (72.4%) providers completed surveys. Mean age of pregnant women was 30.2 (18–45) years. Self-identified race/ethnicity was 45% white, 26% Hispanic, 13% black, 12% Asian and 4% other. Most women had college degrees (84%) and private health insurance (83%). Mean gestation was 28.5 weeks with 4.8%, 37.8% and 57.4%, in the 1st, 2nd and 3rd trimesters, respectively. Women used various sources for pregnancy information (personal contacts, providers, print, audiovisual and online media) but 89.1% cited a provider as their most trusted source, predominantly (85.8%) their physician. 668 (84%) knew vaccines are recommended during pregnancy, specifically influenza (77%) and Tdap (61%) vaccines. 659 (83%) were willing to receive vaccines if recommended by their physician. Factors impacting vaccination decisions included safety for baby, safety for mother and sufficient information, scoring 4.7, 4.5 and 4.2, respectively, on a 5-point scale; less important were additional visit time (2.6), cost (1.9) or needle phobia (1). Women surveyed in the 3rd trimester showed greater acceptance than those earlier in gestation (87% vs 78%; P0.003). Maternal education, ethnicity, insurance, multiple gestation or history of serious illness in a prior infant did not affect willingness to receive vaccines. ConclusionsPregnant women are willing to accept vaccination in pregnancy if recommended by their physician and if sufficient discussion of safety and rationale occurs. Strong physician recommendation, as reported for pediatric vaccination, is essential to optimizing uptake of vaccines during pregnancy.

Human metapneumovirus infection: An emerging problem in high-risk infants

Viral infection is an important cause of upper and lower respiratory tract illness in infants and young children world wide, causing significant respiratory morbidity in affected children. Premature infants, especially those with bronchopulmonary dysplasia (BPD), chronic oxygen dependency and congenital heart disease are regarded as “high risk” infants because a higher proportion of such infants require hospitalization and admission to the pediatric intensive care units. Their problems often continue after discharge from hospital, as they may develop persistent symptoms such as cough and wheeze. This has significant impact on resource utilization, cost of care and quality of life for the infants and their families. A number of viruses such as respiratory syncytial virus (RSV) and adenoviruses are well recognized to be implicated in the pathogenesis of serious lower respiratory tract illness, but in a substantial number of symptomatic children, no virus can be identified. This may be due to a variety of reasons including insensitivity of the specific diagnostic tests at individual hospitals, or the medical profession’s unawareness of newly emerging pathogens. This was indeed the case when researchers in the Netherlands isolated human metapneumovirus (hMPV) from children for the first time in 2001 [1]. Since then, investigations in different coun-

Psychosocial Stress During First Pregnancy Predicts Infant Health Outcomes in the First Postnatal Year.

To evaluate the impact of psychosocial stress during pregnancy on infant health outcomes in the first postnatal year. A sample of 3000 women completed a stress inventory (the Psychosocial Hassles Scale) during their third trimester before first childbirth. Infant health outcomes were measured via maternal report at 1, 6 and 12months postpartum. Poisson regression was used to model the effect of maternal stress during pregnancy on infant health outcomes in the first year, controlling for age, race/ethnicity, education, insurance coverage, marital status, and cigarette smoking during pregnancy. Women who were younger, minority, unmarried, publicly insured and without a college degree were more likely to report high levels of prenatal stress. High prenatal stress was a significant predictor of maternal reporting of gastrointestinal illness (p<0.0001), respiratory illness (p=0.025), and total illness in the first year (p<0.0001). High prenatal stress was also a significant predictor of urgent care visits (p<0.0001) and emergency department visits (p=0.001). It was not a significant predictor of hospitalizations (p=0.36). Maternal prenatal stress is associated with increased maternal reporting of infant illness, as well as increased frequency of both urgent care visits and emergency department visits.

Medicina indígena y males infantiles entre los nahuas de texcoco: Pérdida de la guía, caída de mollera, tiricia y mal de ojo

The paper describes and analyzes concisely four of the most frequent infant illnesses among the Nahuas in the Sierra de Texcoco (Mexico), placing them in the general frame of the characteristic pathologies –“physical or material”, and “spiritual”– characteristic of the region. These are genuine “cultural” diseases that can only be treated by experienced relatives or ritual specialists. In the article the basic characteristics are analyzed in detail by etiology, course and respective therapeutic methods, showing how the illnesses are perceived by the Nahuas through the information collected during the ethnographic research carried out in the region. At the same time, the article reflects about the complex relationship between the Western and the Nahua medical systems that coexist in the Sierra and points out the existen-ce of an intermediate field of therapy, distinctive and camouflaged, that offers answers to the childhood diseases: the family medicine or domestic medicine.

Intracranial hemorrhage and other symptoms in infants associated with human parechovirus in Vienna, Austria.

In Austria, HPeV is a relevant pathogen in sepsis-like disease in infants. The clinical presentation is similar to that described in other studies; cerebral hemorrhage is a new aspect. • Parechovirus infection can cause severe illness in infants. • Symptoms have been described to involve all organs; sepsis-like signs, fever, and irritability are most frequent. • Also in Austria, HPeV plays an important role in severe illnesses in infants. • Severe intracranial hemorrhage is described as a new finding.

Molecular characterization of potential healthcare associated respiratory syncytial virus in three referral hospitals in Kenya, 2009-2011

Respiratory syncytial virus (RSV) is a major cause of community-acquired severe respiratory illness in infants, immunocompromised individuals and the elderly. Limited information exists on healthcare associated RSV infections in developing countries.

Family Adjustment and Parenting Stress When an Infant Has Serious Liver Disease

Parenting stress, problems in family functioning, and lack of fathers' engagement in treatment are associated with poor quality of life in children with chronic illnesses. The aim of the present study was to examine these characteristics in families of infants with serious liver disease in Australia, to inform the provision of mental health care for these families. From September 2009 to May 2013, 42 parents of infants recently diagnosed as having serious liver disease (defined as liver disease that may require transplantation in the future) completed questionnaires about family function, impact of the infant's illness on the family, parent stress symptoms, and fathers' engagement in the care of the child. Participants were recruited from 4 metropolitan children's hospitals in Australia. Parents reported psychological symptoms at similar rates to normative populations. Their reports of family functioning were significantly below mean scores in previously published populations with a medically ill family member (population mean 1.89; mothers mean 1.59; fathers mean 1.61, P < 0.001). Disruption to family roles was significantly correlated with psychological symptoms for mothers (r = 0.48, P < 0.01) and fathers (r = 0.31, P < 0.05). Greater helpfulness of fathers was correlated with lower depression in mothers (r = -0.35, P < 0.05), and fathers' anxiety was correlated with their increased engagement (r = 0.40, P < 0.01). When parents report the presence of psychological symptoms, symptoms are likely to be present in both parents and are associated with difficulties adjusting to disrupted family roles. Father engagement may be protective of mothers' mental health.

Clinical characteristics and molecular epidemiology of Enterovirus infection in infants

Enterovirus (EV) infection is common in infants, but the information with regard to the molecular epidemiology and the associations between types and clinical variables is very scarce. This study includes 195 children <3months old with fever, attended from March 2010 to December 2012 in an emergency department of a tertiary paediatric hospital in whom EV infection was confirmed by real-time PCR in blood and/or cerebrospinal fluid. Clinical and epidemiological data was prospectively collected. In 152 (77.9%) patients, EVs could be typed. The most common type was Echovirus-5 (E5; 32, 21.1%), followed by Echovirus-11 (E11; 18, 11.8%), Echovirus-21 and Echovirus-25 (E21, E25; 11 each one, 7.2%) and Coxsackievirus-B4 (CVB4; 6, 6.6%). The majority of types appeared in spring, but E5 and E25 were found mainly during summer (p < 0.01). E21 was associated with high-grade fever (p < 0.01); E5 with exanthema (p = 0.03) and CVB4 tended to cause meningitis more often than the other types (p = 0.07). The most common EV types were Echovirus-5 and Echovirus-11. Some significant associations between types and epidemiologic and clinical findings were observed. What is Known-What is New • Enteroviruses cause a normally benign illness in young infants, except in some cases. • The molecular epidemiology of Enterovirus infection is not well known in European countries. • This study describes a large number of infants with Enterovirus infection and shows the seasonality of different types, and their associations with epidemiologic and clinical variables.

Sedatives and Analgesics Given to Infants in Neonatal Intensive Care Units at the End of Life

To describe the administration of sedatives and analgesics at the end of life in a large cohort of infants in North American neonatal intensive care units. Data on mortality and sedative and analgesic administration were from infants who died from 1997-2012 in 348 neonatal intensive care units managed by the Pediatrix Medical Group. Sedatives and analgesics of interest included opioids (fentanyl, methadone, morphine), benzodiazepines (clonazepam, diazepam, lorazepam, midazolam), central alpha-2 agonists (clonidine, dexmedetomidine), ketamine, and pentobarbital. We used multivariable logistic regression to evaluate the association between administration of these drugs on the day of death and infant demographics and illness severity. We identified 19 726 infants who died. Of these, 6188 (31%) received a sedative or analgesic on the day of death; opioids were most frequently administered, 5366/19 726 (27%). Administration of opioids and benzodiazepines increased during the study period, from 16/283 (6%) for both in 1997 to 523/1465 (36%) and 295/1465 (20%) in 2012, respectively. Increasing gestational age, increasing postnatal age, invasive procedure within 2 days of death, more recent year of death, mechanical ventilation, inotropic support, and antibiotics on the day of death were associated with exposure to sedatives or analgesics. Administration of sedatives and analgesics increased over time. Infants of older gestational age and those more critically ill were more likely to receive these drugs on the day of death. These findings suggest that drug administration may be driven by severity of illness.

Abstract 132: Methylprednisolone Pulse Therapy for Kawasaki Disease with Symptomatic Myocarditis

Purpose: Kawasaki disease (KD) is an acute febrile illness of infants and young children that is characterized by a systemic vasculitis, especially involving the coronary arteries. Although, sometimes, subclinical myocarditis is combined in KD, symptomatic myocarditis is extremely uncommon. We report a 7 year old boy who developed hypotension and decreased left ventricular systolic function (EF 40%) in the acute phase of KD. Case: A 7 year old boy (height 115 cm, body weight 20 kg) was admitted because of 2 days of persistent fever and left cervical lymphadenopathy (white blood cell count 17,870 /mm 3 , C reactive protein 23.6 mg/dL). Conjunctiva injection and lip redness developed on the 4th day of illness, and hypotension and tachycardia (SBP 59/DBP 29 mmHg, HR 153/bpm) were combined. The echocardiography revealed a decreased ejection fraction (EF) (40%) without chamber dilatation and normal coronary artery size (LM 1.9mm, z score=-1.3, RCA 2.3mm, z score=0.4). The level of N terminal pro BNP was 28,000 pg/mL. With a diagnosis of KD with myocarditis, he was initially treated with inotropics and intravenous immunoglobulin (2 g/kg). Without clinical improvement in spite of initial treatment, A change of coronary arterial size (LM 2.9mm, z score=1.2, RCA 3.1mm, z score=2.3) was developed and decreased LV systolic function (EF 45%) and fever were persisted. Then, he was given 3 daily pulses of intravenous methylprednisolone followed by tapering doses of oral prednisolone. He showed prompt clinical recovery after pulse therapy of intravenous methylprednisolone (SBP 95/DBP 49 mmHg, HR 98/bpm). Although EF was improved (59%), coronary arterial dilatation was progressed (LM 3.4mm, z score=2.4 RCA 5.5mm, z score=7.9). Conclusions: The present case serves to highlight the fact that methylprednisolone should be considered as the priority in children with KD who have symptomatic myocarditis during the acute stage.

Nursing Care of Infants and Children with Bronchiolitis

Bronchiolitisisthemostcommoncauseoflowerrespiratoryinfectioninthefirstyear� of life. It is a leading cause of acute illness and hospitalization for infants and young children worldwide. Previous studies have demonstrated that at least 1% of children younger than 24 months of age are hospitalized for bronchiolitis. These hospitalizations have been found to con- sumeasignificantamountofhealthcareresources.�Theprimarytreatmentofbronchiolitisre- mainslargelysupportivewithadministrationoffluidsandsupplementaryoxygen,�observation� and mechanical ventilation if needed. Other types of treatment remain controversial. Successful treatment of this diagnosis requires coordination of care of a multidisciplinary team. Pediatric nurses and advanced practice pediatric nurses in both primary and acute care clinical settings can play a major role in educating other health care professionals on the use of Evidence-based practice and why it is important to decrease costs and improve patients' outcome by changing the traditional and habitual use of diagnostic and therapeutic options that are no longer rec- ommended by the most recent guidelines. The purpose of this review was to identify the best evidence available for the updated management of infants and children with bronchiolitis. This updatedsimplifiedmanagementofinfantswithbronchiolitiswouldresultinnotonlydecreas- ing the cost of care but also result in a better outcome as mentioned in guidelines according to the recent literature.

Ethnobotanical investigation of indigenous plants used in the management of some infant illnesses in Ibadan, South-Western Nigeria

Ethnobotanical investigation of indigenous plants used in the management of some infant illnesses in Ibadan, South-Western Nigeria

Factors influencing breastfeeding exclusivity during the first 6 months of life in developing countries: a quantitative and qualitative systematic review.

Breastfeeding is the most advantageous feeding option for infants, and epidemiological studies provide evidence for its promotion. The objective of this review was to comprehensively delineate the barriers and facilitators of exclusive breastfeeding of infants aged 0-6 months old by mothers in developing countries. A search of CINAHL, MEDLINE and PsycINFO was carried out to retrieve studies from January 2001 to January 2014. Using our inclusion criteria, we selected studies that described barriers and facilitators of exclusive breastfeeding. Qualitative and quantitative studies were considered. Twenty-five studies involving 11 025 participants from 19 countries were included. Barriers and facilitators of exclusive/full breastfeeding were identified, analysed tabulated and summarised in this review. Maternal employment was the most frequently cited barrier to exclusive breastfeeding. Maternal perceptions of insufficient breast milk supply was pervasive among studies while medical barriers related to illness of mothers and/or infants as well as breast problems, rather than health care providers. Socio-cultural factors such as maternal and significant other's beliefs about infant nutrition also often constitute strong barriers to exclusive breastfeeding. Despite these barriers, mothers in developing countries often possess certain personal characteristics and develop strategic plans to enhance their success at breastfeeding. Health care providers should be informed about the determinants of exclusive breastfeeding and provide practical anticipatory guidance targeted at overcoming these barriers. In so doing, health care providers in developing countries can contribute to improving maternal and child health outcomes.

Designs of two randomized, community-based trials to assess the impact of influenza immunization during pregnancy on respiratory illness among pregnant women and their infants and reproductive outcomes in rural Nepal.

BackgroundAmong the most important causes of illness and death in both pregnant women and their newborn infants are respiratory infections including influenza. Pregnant women in North America have a 4 to 5 fold excess rate of hospitalization compared to non-pregnant women. Rates of infant hospitalization associated with influenza are much higher than in their mothers. Fully half of children hospitalized for influenza in the US are in the age group 0–5 months, a group where no vaccine is licensed. Data on influenza are much fewer in low income countries where the risks of serious morbidity and mortality are much higher. A recent trial in Bangladesh suggested that influenza immunization in pregnant women could have important protective effects against influenza in both mothers and their infants. These trials were designed to provide additional evidence about the effect of influenza vaccination in pregnancy in settings where influenza may circulate for up to ten months/year.Methods/DesignWe conducted a consecutive pair of community-based, placebo-controlled, randomized trials of influenza vaccination of pregnant women in a rural district in southern Nepal. Two trials were conducted to insure, as much as possible, the match of circulating strains with those included in the vaccine. Eligible women included all who were or became pregnant over a one year period. Each trial included a one year cohort of pregnant women who were individually randomized to the influenza vaccine available at the time of their enrollment or placebo. Exclusions included a history of allergy to vaccine components, prior influenza vaccine receipt, and for the second trial, participation in the first trial. Morbidity was assessed on a weekly basis for women throughout pregnancy and through 180 days post-partum. Infants were followed weekly through 180 days. Primary outcomes included: 1) incidence of influenza like illness in women, 2) incidence of laboratory confirmed influenza illness in infants, and 3) birthweight among newborn infants.DiscussionWe have presented the design and methods of two randomized trials of influenza immunization of pregnant women.Trial registrationClinicaltrials.gov: (NCT01034254).

An Explorative Qualitative Study of Experiences and Challenges to Exclusive Breastfeeding Among Mothers in Rural Zimbabwe

Breastfeeding is one of the most effective public health interventions known to reduce illness and deaths in infants and young children. While Zimbabwe has a breastfeeding culture, exclusive breastfeeding has remained low over the last decade. This study explored factors that enable and hinder exclusive breastfeeding in a rural district of Zimbabwe. Ten mothers and 5 key informants with breastfeeding experience were interviewed. Interviews were audiotaped, transcribed in Ndebele, translated into English, and analyzed using thematic analysis. Notable gaps still exist regarding mothers’ understanding of exclusive breastfeeding. Hunger, myths, and traditional beliefs around breastfeeding, as well as mixed and inconsistent messages regarding HIV/AIDS and breastfeeding, remain barriers to exclusive breastfeeding in the study area. Support from significant others, good nutrition for the breastfeeding mother, and knowledge about breastfeeding emerged as factors enabling exclusive breastfeeding. Messaging on breastfeeding and HIV/AIDS need to be consistent. Breastfeeding messages ought to be context specific, targeting custodians of tradition and belief systems, including men and significant others, to create a supportive and enabling environment for mothers to exclusively breastfeed. Whether hunger and differences in breastfeeding patterns between boys and girls affect infant feeding practices warrants further research.

Fine mapping and characterization of the L-polymerase-binding domain of the respiratory syncytial virus phosphoprotein.

The minimum requirement for an active RNA-dependent RNA polymerase of respiratory syncytial virus (RSV) is a complex made of two viral proteins, the polymerase large protein (L) and the phosphoprotein (P). Here we have investigated the domain on P that is responsible for this critical P-L interaction. By use of recombinant proteins and serial deletions, an L binding site was mapped in the C-terminal region of P, just upstream of the N-RNA binding site. The role of this molecular recognition element of about 30 amino acid residues in the L-P interaction and RNA polymerase activity was evaluated in cellula using an RSV minigenome system and site-directed mutagenesis. The results highlighted the critical role of hydrophobic residues located in this region. Respiratory syncytial virus (RSV) is the leading cause of lower respiratory tract illness in infants. Since no vaccine and no good antivirals against RSV are available, it is essential to better understand how the viral machinery functions in order to develop new antiviral strategies. Like all negative-strand RNA viruses, RSV codes for its own machinery to replicate and transcribe its genome. The core of this machinery is composed of two proteins, the phosphoprotein (P) and the large protein (L). Here, using recombinant proteins, we have mapped and characterized the P domain responsible for this L-P interaction and the formation of an active L-P complex. These findings extend our understanding of the mechanism of action of RSV RNA polymerase and allow us to define a new target for the development of drugs against RSV.