Frequency and Duration of Rhinovirus Infections in Children With Cystic Fibrosis and Healthy Controls: A Longitudinal Cohort Study.

BACKGROUND: Respiratory viral infections are an important cause of morbidity in patients with chronic respiratory diseases, such as cystic fibrosis (CF). We hypothesized that patients with CF are more susceptible to human rhinovirus (HRV) infections than healthy controls. METHODS: In a 6-month winter period, 20 young children with CF (0-7 years) and 18 age-matched healthy controls were sampled biweekly for HRV-polymerase chain reaction using nasopharyngeal swabs, irrespective of respiratory symptoms. Respiratory symptoms were scored twice a week. If any symptom was present, an additional sample was obtained. All HRV-positive samples were genotyped to distinguish HRV subtypes. RESULTS: We analyzed 645 samples, with comparable total numbers of samples in both groups. HRV was detected in 40.8% of all analyzed samples. Children with CF had significantly more HRV-positive samples compared with healthy controls, with a mean number (± standard deviation) of 8.1 ± 2.3 versus 5.7 ± 2.9 positive samples per individual (P < 0.01). Prolonged detection (>2 weeks) with the same HRV subtype occurred more frequently in the CF patients (P < 0.01). The genetic distribution and pattern of phylogenetic diversity of the different HRV subtypes were similar in both groups. CONCLUSIONS: This is the first in vivo longitudinal study showing that HRV is detected more frequently and persists for longer periods in CF patients compared with healthy controls. This might indicate increased viral replication and/or decreased antiviral defense in patients with CF.

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.

Decreased lung function precedes severe respiratory syncytial virus infection and post-respiratory syncytial virus wheeze in term infants.

It is unknown why respiratory syncytial virus (RSV) causes mild disease in some children and severe disease, requiring hospitalisation, in others. We aimed to assess whether diminished premorbid lung function in healthy term infants predisposes to hospitalisation during RSV bronchiolitis, and to post-RSV wheeze. In a prospective birth cohort study of unselected term healthy children, neonatal lung function was measured before the age of 2 months (n=2133). From birth through the first year of life, respiratory symptoms were recorded in a diary, and general practitioner consultations and hospitalisations were documented. In a subgroup (n=417) repeated nose and throat swabs were collected for PCR to detect RSV infections. Median neonatal respiratory system compliance (Crs) was significantly lower (41.2 versus 47.4 mL · kPa(-1), p=0.03) and resistance (Rrs) was higher (8.2 versus 6.3 kPa · s · L(-1), p=0.10) in hospitalised RSV patients (n=18) compared with nonhospitalised RSV-positive infants (n=84). Every 10 mL · kPa(-1) increase in Crs was associated with 55% less post-RSV wheeze (OR 0.56, 95% CI 0.35-0.90), and each kPa · s · L(-1) increase in Rrs was associated with 42% more post-RSV wheeze, which was only marginally explained by pre-RSV wheeze or severity of the RSV disease. This unselected birth cohort study shows for the first time that decreased lung function at birth predisposes to severe RSV disease, and to post-RSV wheeze.

Human rhinovirus and wheezing: short and long-term associations in children.

OBJECTIVES: Human rhinoviruses (HRVs) have been suggested to play a role in the development of childhood wheezing. However, whether HRV is causally related to the development of wheezing or HRV-associated wheeze is merely an indicator of disease susceptibility is unclear. Our aim was to study the role of HRV during infancy in the development of lower respiratory disease during infancy and childhood. METHODS: In a population-based birth cohort, during the 1st year of life, nose and throat swabs were collected on a monthly basis, regardless of any symptoms. Polymerase chain reaction was used to detect an extensive panel of respiratory pathogens. Lung function was measured before 2 months of age. Information on respiratory symptoms was collected by daily questionnaires and electronic patient files. RESULTS: 1425 samples were collected in 140 infants. Both the presence of (single or multiple) pathogens (HRV equal to other pathogens) and increased respiratory system resistance were significantly associated with lower respiratory symptoms during infancy. HRV presence during infancy was not associated with the risk of wheezing at age 4, but every HRV episode with wheezing increased the risk of wheezing at age 4 (odds ratio 1.9, 1.1-3.5). This association weakened after adjustment for lung function (odds ratio 1.4, 0.7-2.9). CONCLUSIONS: HRV and other viruses are associated with lower respiratory symptoms during infancy, as well as a high presymptomatic respiratory system resistance. HRV presence during infancy is not associated with childhood wheezing, but wheeze during a HRV episode is an indicator of children at high risk for childhood wheeze, partly because of a reduced neonatal lung function.

High concentrations of amniotic fluid proinflammatory cytokines in healthy neonates are associated with low risk of respiratory syncytial virus bronchiolitis.

BACKGROUND: The burden of respiratory syncytial virus (RSV) bronchiolitis in individual children and their families, the medical system and society is considerable. Mechanisms underlying RSV bronchiolitis in healthy term infants are largely unknown. Sterile intraamniotic inflammation and chorioamnionitis have been associated with increased lung volume and compliance. OBJECTIVE: The aim of this study was to determine whether high amniotic fluid interleukin-8 (IL-8), and tumor necrosis factor-α protect against RSV bronchiolitis in healthy term infants. METHODS: We conducted a prospective birth cohort study of healthy term newborns, born after uncomplicated pregnancy. Amniotic fluid was collected during labor. In case of medical attention for respiratory symptoms during the first year of life, a nose-throat swab was taken to establish the presence of respiratory viruses by polymerase chain reaction. RESULTS: Physician-attended RSV infection was observed in 27 (9.3%) of 292 children at median age 6 months. Amniotic fluid concentrations of IL-8 were higher in children without physician-attended RSV infection than in children with physician-attended RSV infection (11.1 versus 5.5 ng/mL; P = 0.002). Similarly, in children without physician-attended RSV, the proportion of detectable amniotic fluid tumor necrosis factor-α was higher (159/265 [60%] versus 8/27 [30%]; P = 0.002). Among children with physician-attended RSV infection, amniotic fluid IL-8 was inversely correlated to the number of wheezing days during the first year of life (ρ = -0.38; P = 0.048). CONCLUSIONS: High concentrations of amniotic fluid IL-8 and tumor necrosis factor-α are associated with low risk of RSV bronchiolitis in healthy term infants. We hypothesize that direct exposure of fetal lungs to proinflammatory signals induces local protection against viral infection during infancy.

Highly frequent infections with human rhinovirus in healthy young children: a longitudinal cohort study.

BACKGROUND: Human rhinoviruses (HRVs) are an important cause of respiratory tract infections. OBJECTIVES: We questioned whether the high prevalence rates of HRVs found in epidemiological studies is due to long-term individual continuity or a result of frequent infections with different HRV subtypes. STUDY DESIGN: In a 6-month winter period 18 healthy controls, aged 0-7 years, were at least sampled every two weeks for HRV-PCR, irrespective of respiratory symptoms. All HRV positive samples were genotyped to determine HRV diversity. RESULTS: In total 272 samples were collected. HRV was found in 101/272 (37%) samples. Genotyping revealed 27 different HRV subtypes. A median of 3.0 different HRV subtypes was found per child. Re-infections and continuity with identical HRV sequences were observed. The number of HRVs were higher in the youngest age group (p=0.01) and they had more different HRV subtypes (p=0.05) compared to oldest age group. CONCLUSIONS: We found a high HRV exposition with a considerable diverse population of HRV subtypes in young children. These results have major implications for future research into the pathogenic role of HRV in respiratory diseases. Characterisation of subtypes will be necessary to discriminate between prolonged continuity and re-infections in patients with respiratory diseases.

Cord blood vitamin D deficiency is associated with respiratory syncytial virus bronchiolitis.

BACKGROUND: Respiratory syncytial virus (RSV) is the most important pathogen causing severe lower respiratory tract infection (LRTI) in infants. Epidemiologic and basic studies suggest that vitamin D may protect against RSV LRTI. OBJECTIVE: To determine the association between plasma vitamin D concentrations at birth and the subsequent risk of RSV LRTI. DESIGN: A prospective birth cohort study was performed in healthy term neonates. Concentrations of 25-hydroxyvitamin D (25-OHD) in cord blood plasma were related to RSV LRTI in the first year of life, defined as parent-reported LRTI symptoms in a daily log and simultaneous presence of RSV RNA in a nose-throat specimen. RESULTS: The study population included 156 neonates. Eighteen (12%) developed RSV LRTI. The mean plasma 25-OHD concentration was 82 nmol/L. Overall, 27% of neonates had 25-OHD concentrations < 50 nmol/L, 27% had 50-74 nmol/L and only 46% had 25-OHD 75 nmol/L. Cord blood 25-OHD concentrations were strongly associated with maternal vitamin D3 supplementation during pregnancy. Concentrations of 25-OHD were lower in neonates who subsequently developed RSV LRTI compared with those who did not (65 nmol/L versus 84 nmol/L, P = .009). Neonates born with 25-OHD concentrations <50 nmol/L had a sixfold (95% confidence interval: 1.6-24.9; P = .01) increased risk of RSV LRTI in the first year of life compared with those with 25-OHD concentrations ≥ 75 nmol/L. CONCLUSIONS: Vitamin D deficiency in healthy neonates is associated with increased risk of RSV LRTI in the first year of life. Intensified routine vitamin D supplementation during pregnancy may be a useful strategy to prevent RSV LRTI during infancy.

The influence of neonatal lung function on rhinovirus-associated wheeze.

RATIONALE: Several studies have shown that the occurrence of wheezing illnesses during the first year of life is associated with lower levels of lung function shortly after birth and before any respiratory illness. It has been suggested that reduced lung function early in life predisposes infants to wheezing during viral respiratory infections, but the association between neonatal lung function and subsequent confirmed viral infections has never been investigated. OBJECTIVES: To study the influence between neonatal lung function and the occurrence of human rhinovirus (HRV)-associated wheeze. METHODS: In a prospective birth cohort study, infants were followed from birth through the first year of life with daily questionnaires about respiratory symptoms. Neonatal lung function was performed within the first 2 months of life. Nose and throat swabs were collected during episodes with respiratory symptoms. Polymerase chain reaction was used to detect single HRV infections. MEASUREMENTS AND MAIN RESULTS: In 176 of the 202 infants (87%) with a single HRV infection, valid lung function measurements were obtained. The risk of wheeze was 1.49 times higher for each SD increase of airway resistance. The adjusted risk (corrected for possible important confounders) for wheeze was 1.77 (95% confidence interval, 1.16-2.69; P = 0.01) times higher for each SD increase of airway resistance. Maternal smoking during pregnancy was independently associated with wheeze (odds ratio 4.42; 95% confidence interval, 1.27-15.5; P = 0.02). CONCLUSIONS: This study showed that total lung resistance is clearly associated with HRV-associated wheeze. Moreover, HRV-associated wheeze might be the first sign to recognize infants with reduced neonatal lung function.

Clinical prediction rule for RSV bronchiolitis in healthy newborns: prognostic birth cohort study.

OBJECTIVE: Our goal was to determine predictors of respiratory syncytial virus (RSV) lower respiratory tract infection (LRTI) among healthy newborns. METHODS: In this prospective birth cohort study, 298 healthy term newborns born in 2 large hospitals in the Netherlands were monitored throughout the first year of life. Parents kept daily logs and collected nose/throat swabs during respiratory tract infections. The primary outcome was RSV LRTI, which was defined on the basis of the combination of positive RSV polymerase chain reaction results and acute wheeze or moderate/severe cough. RESULTS: Of the 298 children, 42 (14%) developed RSV LRTI. Independent predictors for RSV LRTI were day care attendance and/or siblings, high parental education level, birth weight of >4 kg, and birth in April to September. The area under the receiver operating characteristic curve was 0.72 (95% confidence interval: 0.64-0.80). We derived a clinical prediction rule; possible scores ranged from 0 to 5 points. The absolute risk of RSV LRTI was 3% for children with scores of ≤2 (20% of all children) and 32% for children with all 4 factors (scores of 5; 8% of all children). Furthermore, 62% of the children with RSV LRTI experienced wheezing during the first year of life, compared with 36% of the children without RSV LRTI. CONCLUSIONS: A simple clinical prediction rule identifies healthy newborns at risk of RSV LRTI. Physicians can differentiate between children with high and low risks of RSV LRTI and subsequently can target preventive and monitoring strategies toward children at high risk.

Respiratory pathogens in respiratory tract illnesses during the first year of life: a birth cohort study.

BACKGROUND: Respiratory virus infections are the most important trigger of respiratory illnesses in childhood. Data on the occurrence and the clinical impact of respiratory pathogens in the general population of infants are scarce. Therefore, we described the occurrence and clinical impact of respiratory pathogens in infants with respiratory tract infections during the first year of life. METHODS: In a prospective birth cohort study, infants were followed from birth through the first year of life with daily questionnaires about respiratory symptoms. Nose and throat swabs were collected during episodes with respiratory symptoms. Polymerase chain reaction was used to detect an extensive panel of respiratory pathogens. RESULTS: The parents reported a median of 5 respiratory episodes per infant per year. A total of 668 respiratory samples were collected in 305 infants. One or more respiratory pathogens were detected in 85% of the samples. The most common respiratory pathogens were human rhinovirus (HRV) (73% of the samples), respiratory syncytial virus (RSV) (11%), and coronavirus (8%). HRV infections were associated with a prolonged period of symptoms compared with RSV (P = 0.03). Infections with RSV were associated with more physician visits than HRV infections (P = 0.06). CONCLUSION: We found a high prevalence of respiratory pathogens among infants with parent-reported respiratory illnesses in the first year of life, with HRV being the most prevalent. Although RSV infections seemed to be responsible for the most severe symptoms compared with HRV, the overall burden of disease was highest for HRV infections.

Respiratory pathogens in children with and without respiratory symptoms.

OBJECTIVES: To investigate the occurrence of respiratory pathogens in samples from children with and without respiratory symptoms and to identify whether age and/ or coinfections modify the impact of respiratory pathogens on symptoms. STUDY DESIGN: In a prospective longitudinal study, 18 children were sampled biweekly for respiratory pathogens, irrespective of respiratory symptoms. Polymerase chain reaction was performed for 13 respiratory pathogens. Episodes were defined "asymptomatic" if no symptoms of any respiratory tract illness were present between 1 week before and 1 week after sampling. RESULTS: A total of 230 samples were collected. In 56% of the symptomatic episodes, a pathogen was detected, compared with 40% of the asymptomatic episodes (P = .03). Rhinovirus and coronaviruses were most prevalent in both symptomatic and asymptomatic episodes. In the youngest children, 9% of the pathogen-positive episodes were asymptomatic, compared with 36% in the oldest children (P = .01). Multiple pathogens were found in 17% of the symptomatic episodes and in 3% of the asymptomatic episodes (P = .02). CONCLUSIONS: Respiratory pathogens are frequently detected in samples from children with no respiratory symptoms. Symptomatic cases occurred more often in younger children and with detections of more than 1 respiratory pathogen.

Prevalence and impact of respiratory viral infections in young children with cystic fibrosis: prospective cohort study.

OBJECTIVE: We aimed to investigate differences in upper and lower respiratory tract symptoms in relation to respiratory viral infections detected with polymerase chain reaction assays in young children with cystic fibrosis and healthy control subjects. METHODS: In a 6-month winter period, 20 young children with cystic fibrosis and 18 age-matched, healthy, control subjects were contacted twice per week for detection of symptoms of an acute respiratory illness. If any symptom was present, then a home visit was made for physical examination and collection of nasopharyngeal swabs for viral analysis. In addition, parents were instructed to collect nasopharyngeal swabs every 2 weeks. RESULTS: Children with cystic fibrosis and healthy control subjects had similar frequencies of acute respiratory illnesses (3.8+/-1.0 and 4.2+/-1.7 episodes, respectively). Although there were no significant differences in upper respiratory tract symptoms, the children with cystic fibrosis had longer periods of lower respiratory tract symptoms (22.4+/-22.2 vs 12.8+/-13.8 days) and a higher mean severity score per episode (2.35+/-0.64 vs 1.92+/-0.46). In addition, similar increases in upper respiratory tract symptom scores were associated with significantly greater increases in lower respiratory tract symptom scores in children with cystic fibrosis. No differences in the seasonal occurrences and distributions of respiratory viruses were observed, with picornaviruses and coronaviruses being the most prevalent. CONCLUSIONS: Although there were no differences in the seasonal occurrences and distributions of polymerase chain reaction-detected respiratory viruses, acute respiratory illnesses were frequently associated with increased lower respiratory tract morbidity in young children with cystic fibrosis.

Prevalence and pathogenicity of WU and KI polyomaviruses in children, the Netherlands.

A longitudinal study in 2004 and 2005 detected polyomaviruses WU and KI in 44% and 17% of children with and without respiratory symptoms, respectively, in the Netherlands. In some children both viruses were detected for long periods. In several symptomatic children no other respiratory pathogen was detected.

Risk factors for acute respiratory tract infections in general practitioner patients in The Netherlands: a case-control study.

BACKGROUND: Acute respiratory tract infections (ARTI) are an important public health problem. Improved identification of risk factors might enable targeted intervention. Therefore we carried out a case-control study with the aim of identifying environmental risk factors for ARTI consultations in the Dutch general population. METHODS: A subset of patients visiting their GP in the period of 2000-2003 with an ARTI (cases) and age-matched controls (visiting for other complaints) were included in a case-control study. They were asked to complete a questionnaire about potential risk factors. Conditional logistic regression was used to calculate odds ratio's (OR) and 95% confidence intervals (CI) to estimate the independent effect of potential risk factors. RESULTS: A total of 493 matched pairs of case and control subjects were enrolled. Exposure to persons with respiratory complaints, both inside and outside the household, was found to be an independent risk factor for visiting a GP with an ARTI (respectively ORadj = 1.9 and ORadj = 3.7). Participants exposed to dampness or mould at home (ORadj=0.5) were significantly less likely to visit their GP. In accordance with the general risk of consultations for ARTI, participants with a laboratory-confirmed ARTI who were exposed to persons with respiratory complaints outside the household were also significantly more likely to visit their GP (ORadj=2.5). CONCLUSION: This study confirmed that heterogeneity in the general population as well as in pathogens causing ARTI makes it complicated to detect associations between potential risk factors and respiratory infections. Whereas it may be difficult to intervene on the risk posed by exposure to persons with respiratory complaints, transmission of ARTI in the general population might be reduced by improved hygienic conditions.

Human coronavirus 229E encodes a single ORF4 protein between the spike and the envelope genes.

BACKGROUND: The genome of coronaviruses contains structural and non-structural genes, including several so-called accessory genes. All group 1b coronaviruses encode a single accessory protein between the spike and envelope genes, except for human coronavirus (HCoV) 229E. The prototype virus has a split gene, encoding the putative ORF4a and ORF4b proteins. To determine whether primary HCoV-229E isolates exhibit this unusual genome organization, we analyzed the ORF4a/b region of five current clinical isolates from The Netherlands and three early isolates collected at the Common Cold Unit (CCU) in Salisbury, UK. RESULTS: All Dutch isolates were identical in the ORF4a/b region at amino acid level. All CCU isolates are only 98% identical to the Dutch isolates at the nucleotide level, but more closely related to the prototype HCoV-229E (>98%). Remarkably, our analyses revealed that the laboratory adapted, prototype HCoV-229E has a 2-nucleotide deletion in the ORF4a/b region, whereas all clinical isolates carry a single ORF, 660 nt in size, encoding a single protein of 219 amino acids, which is a homologue of the ORF3 proteins encoded by HCoV-NL63 and PEDV. CONCLUSION: Thus, the genome organization of the group 1b coronaviruses HCoV-NL63, PEDV and HCoV-229E is identical. It is possible that extensive culturing of the HCoV-229E laboratory strain resulted in truncation of ORF4. This may indicate that the protein is not essential in cell culture, but the highly conserved amino acid sequence of the ORF4 protein among clinical isolates suggests that the protein plays an important role in vivo.

Measurement of antibodies to avian influenza virus A(H7N7) in humans by hemagglutination inhibition test.

During the epizootic of highly pathogenic avian influenza A(H7N7) in 2003 in The Netherlands, RT-PCR and culture confirmed infection was detected in 89 persons who were ill. A modified hemagglutination inhibition (HI) test using horse erythrocytes and 2 hemagglutinating units of virus was applied to assess retrospectively the extent of human (subclinical) infection. Validation of the HI-test with sera from 34 RT-PCR and culture confirmed A(H7) infected persons and sera from 100 persons from a human influenza vaccine trial in autumn 2002 showed that this HI-test had a sensitivity of 85% and a specificity of 100% when using a cut-off titer of > or =10. Using this cut-off value, A(H7) specific antibodies were detected in 49% of 508 persons exposed to poultry and in 64% of 63 persons exposed to A(H7) infected persons. Correlation of seropositivity with the occurrence of eye symptoms in exposed persons who had not received antiviral prophylaxis and of reduced seropositivity with taking antiviral prophylaxis provided further evidence that the A(H7) HI antibody titers were real. In conclusion, by applying an HI-test using horse erythrocytes human antibodies against the avian A(H7N7) virus were detected with high sensitivity and specificity in an unexpectedly high proportion of exposed persons.

A case-control study of acute respiratory tract infection in general practice patients in The Netherlands.

BACKGROUND: Acute respiratory tract infections (ARTIs) are responsible for considerable morbidity in the community, but little is known about the presence of respiratory pathogens in asymptomatic individuals. We hypothesized that asymptomatic persons could have a subclinical infection and thus act as a source of transmission. METHODS: During the period of 2000-2003, all patients with ARTI who visited their sentinel general practitioner had their data reported to estimate the incidence of ARTI in Dutch general practices. A random selection of these patients (case patients) and an equal number of asymptomatic persons visiting for other complaints (control subjects) were included in a case-control study. Nose and throat swabs of participants were tested for a broad range of pathogens. RESULTS: The overall incidence of ARTI was 545 cases per 10,000 person-years, suggesting that, in the Dutch population, an estimated 900,000 persons annually consult their general practitioner for respiratory complaints. Rhinovirus was most common in case patients (24%), followed by influenza virus type A (11%) and coronavirus (7%). Viruses were detected in 58% of the case patients, beta -hemolytic streptococci group A were detected in 11%, and mixed infections were detected in 3%. Pathogens were detected in approximately 30% of control subjects, particularly in the youngest age groups. CONCLUSION: This study confirms that most ARTIs are viral and supports the reserved policy of prescribing antibiotics. In both case and control subjects, rhinovirus was the most common pathogen. Of bacterial infections, only group A beta-hemolytic streptococci were more common in case patients than in control subjects. Furthermore, we demonstrated that asymptomatic persons might be a neglected source of transmission.

Transmission of H7N7 avian influenza A virus to human beings during a large outbreak in commercial poultry farms in the Netherlands.

BACKGROUND: An outbreak of highly pathogenic avian influenza A virus subtype H7N7 started at the end of February, 2003, in commercial poultry farms in the Netherlands. Although the risk of transmission of these viruses to humans was initially thought to be low, an outbreak investigation was launched to assess the extent of transmission of influenza A virus subtype H7N7 from chickens to humans. METHODS: All workers in poultry farms, poultry farmers, and their families were asked to report signs of conjunctivitis or influenza-like illness. People with complaints were tested for influenza virus type A subtype H7 (A/H7) infection and completed a health questionnaire about type of symptoms, duration of illness, and possible exposures to infected poultry. FINDINGS: 453 people had health complaints--349 reported conjunctivitis, 90 had influenza-like illness, and 67 had other complaints. We detected A/H7 in conjunctival samples from 78 (26.4%) people with conjunctivitis only, in five (9.4%) with influenza-like illness and conjunctivitis, in two (5.4%) with influenza-like illness only, and in four (6%) who reported other symptoms. Most positive samples had been collected within 5 days of symptom onset. A/H7 infection was confirmed in three contacts (of 83 tested), one of whom developed influenza-like illness. Six people had influenza A/H3N2 infection. After 19 people had been diagnosed with the infection, all workers received mandatory influenza virus vaccination and prophylactic treatment with oseltamivir. More than half (56%) of A/H7 infections reported here arose before the vaccination and treatment programme. INTERPRETATION: We noted an unexpectedly high number of transmissions of avian influenza A virus subtype H7N7 to people directly involved in handling infected poultry, and we noted evidence for person-to-person transmission. Our data emphasise the importance of adequate surveillance, outbreak preparedness, and pandemic planning.