The Seattle virus watch. 3. Evaluation of isolation methods and summary of infections detected by virus isolations

Household transmission of influenza A and B within a prospective cohort during the 2013-2014 and 2014-2015 seasons

People living within the same household as someone ill with influenza are at increased risk of infection. Here, we use Markov chain Monte Carlo methods to partition the hazard of influenza illness within a cohort into the hazard from the community and the hazard from the household. During the 2013‐2014 influenza season, 49 (4.7%) of the 1044 people enrolled in a community surveillance cohort had an acute respiratory illness (ARI) attributable to influenza. During the 2014‐2015 influenza season, 50 (4.7%) of the 1063 people in the cohort had an ARI attributable to influenza. The secondary attack rate from a household member was 2.3% for influenza A (H1) during 2013‐2014, 5.3% for influenza B during 2013‐2014, and 7.6% for influenza A (H3) during 2014‐2015. Living in a household with a person ill with influenza increased the risk of an ARI attributable to influenza up to 350%, depending on the season and the influenza virus circulating within the household.

Continuous Invasion by Respiratory Viruses Observed in Rural Households During a Respiratory Syncytial Virus Seasonal Outbreak in Coastal Kenya

Background

Households are high-intensity close-contact environments favorable for transmission of respiratory viruses, yet little is known for low-income settings.

Methods

Active surveillance was completed on 47 households in rural coastal Kenya over 6 months during a respiratory syncytial virus (RSV) season. Nasopharyngeal swabs (NPSs) were taken from 483 household members twice weekly irrespective of symptoms. Using molecular diagnostics, NPSs from 6 households were screened for 15 respiratory viruses and the remainder of households only for the most frequent viruses observed: rhinovirus (RV), human coronavirus (HCoV; comprising strains 229E, OC43, and NL63), adenovirus (AdV), and RSV (A and B).

Results

Of 16928 NPSs tested for the common viruses, 4259 (25.2%) were positive for ≥1 target; 596 (13.8%) had coinfections. Detection frequencies were 10.5% RV (1780), 7.5% HCoV (1274), 7.3% AdV (1232), and 3.2% RSV (537). On average, each household and individual had 6 and 3 different viruses detected over the study period, respectively. Rhinovirus and HCoV were detected in all the 47 households while AdV and RSV were detected in 45 (95.7%) and 40 (85.1%) households, respectively. The individual risk of infection over the 6-month period was 93.4%, 80.1%, 71.6%, 61.5%, and 37.1% for any virus, RV, HCoV, AdV, and RSV, respectively. NPSs collected during symptomatic days and from younger age groups had higher prevalence of virus detection relative to respective counterparts. RSV was underrepresented in households relative to hospital admission data.

Conclusions

In this household setting, respiratory virus infections and associated illness are ubiquitous. Future studies should address the health and economic implications of these observations.

Inactivation of adenoviruses, enteroviruses, and murine norovirus in water by free chlorine and monochloramine

Inactivation of infectious viruses during drinking water treatment is usually achieved with free chlorine. Many drinking water utilities in the United States now use monochloramine as a secondary disinfectant to minimize disinfectant by-product formation and biofilm growth. The inactivation of human adenoviruses 2, 40, and 41 (HAdV2, HAdV40, and HAdV41), coxsackieviruses B3 and B5 (CVB3 and CVB5), echoviruses 1 and 11 (E1 and E11), and murine norovirus (MNV) are compared in this study. Experiments were performed with 0.2 mg of free chlorine or 1 mg of monochloramine/liter at pH 7 and 8 in buffered reagent-grade water at 5 degrees C. CT values (disinfectant concentration x time) for 2- to 4-log(10) (99 to 99.99%) reductions in virus titers were calculated by using the efficiency factor Hom model. The enteroviruses required the longest times for chlorine inactivation and MNV the least time. CVB5 required the longest exposure time, with CT values of 7.4 and 10 mg x min/liter (pH 7 and 8) for 4-log(10) inactivation. Monochloramine disinfection was most effective for E1 (CT values ranged from 8 to 18 mg x min/liter for 2- and 3-log(10) reductions, respectively). E11 and HAdV2 were the least susceptible to monochloramine disinfection (CT values of 1,300 and 1,600 mg-min/liter for 3-log(10) reductions, respectively). Monochloramine inactivation was most successful for the adenoviruses, CVB5, and E1 at pH 7. A greater variation in inactivation rates between viruses was observed during monochloramine disinfection than during chlorine disinfection. These data will be useful in drinking water risk assessment studies and disinfection system planning.

Waterborne adenovirus

Adenoviruses are associated with numerous disease outbreaks, particularly those involving d-cares, schools, children's camps, hospitals and other health care centers, and military settings. In addition, adenoviruses have been responsible for many recreational water outbreaks, including a great number of swimming pool outbreaks than any other waterborne virus (Gerba and Enriquez 1997). Two drinking water outbreaks have been documented for adenovirus (Divizia et al. 2004; Kukkula et al. 1997) but none for food. Of the 51 known adenovirus serotypes, one third are associated with human disease, while other infections are asymptomatic. Human disease associated with adenovirus infections include gastroenteritis, respiratory infections, eye infections, acute hemorrhagic cystitis, and meningoencephalitis (Table 2). Children and the immunocompromised are more severely impacted by adenovirus infections. Subsequently, adenovirus is included in the EPA's Drinking Water Contaminant Candidate List (CCL), which is a list of unregulated contaminants found in public water systems that may pose a risk to public health (National Research Council 1999). Adenoviruses have been detected in various waters worldwide including wastewater, river water, oceans, and swimming pools (Hurst et al. 1988; Irving and Smith 1981; Pina et al. 1998). Adenoviruses typically outnumber the enteroviruses, when both are detected in surface waters. Chapron et al. (2000) found that 38% of 29 surface water samples were positive for infectious Ad40 and Ad41. Data are lacking regarding the occurrence of adenovirus in water in the US, particularly for groundwater and drinking water. Studies have shown, however, that adenoviruses survive longer in water than enteroviruses and hepatitis A virus (Enriquez et al. 1995), which may be due to their double-stranded DNA. Risk assessments have been conducted on waterborne adenovirus (Crabtree et al. 1997; van Heerden et al. 2005c). Using dose-response data for inhalation from Couch et al. (1966), human health risks of infection, illness and death have been determined for various adenovirus exposures. Crabtree et al. (1997) conclude that, even at an adenovirus concentration of 1 per 1,000 L of drinking water, annual risks of infection exceed the suggested risk recommendation of 1 x 10(-4) per yr (Regli et al. 1991) (Table 8). Using the same exposure and dose-response assumptions, van Heerden et al. (2005c) determined annual risks of infection to be 1-1.7 x 10(-1) for two drinking water samples from South Africa containing 1.40 and 2.45 adenoviruses per 10,000 L, respectively. This present study estimated annual risks of infection associated with varying levels of adenoviruses per 100 L (Table 9). By assuming a 2 L/d exposure and utilizing the exponential model at r = 0.4172 (Haas et al. 1993), yearly risks exceed the risk recommendation of 1 x 10(-4) at every exposure level. There are limited data regarding the removal of adenoviruses by conventional water treatment or other physical-chemical treatment processes, but studies do suggest that adenoviruses are of equal or greater sensitivity to oxidizing disinfectants, when compared to waterborne viruses (the most resistant to ultraviolet light). Data suggest that the chlorine doses applied to control other waterborne viruses are more effective against adenovirus, resulting in a greater than 4-log10 removal of adenoviruses by conventional treatment and chlorination. If treatment can achieve a 4-log10 removal of adenoviruses, then, based on the risk levels presented in Table 9, surface water concentrations should not exceed 0.5 adenoviruses per 100 L (Fig. 2). More data are needed regarding effectiveness of water treatment against adenovirus and the human-virus dose-response relationship to fully understand the role of adenovirus as a waterborne public health threat.

Epidemiology

The common cold is the result of an upper respiratory tract infection causing an acute syndrome characterised by a combination of non-specific symptoms, including sore throat, cough, fever, rhinorrhoea, malaise, headache, and myalgia. Respiratory viruses, alone or in combination, are the most common cause. The course f illness can be complicated by bacterial agents, causing pharyngitis or sinusitis, but the are a rare cause of cold and flu-like illnesses (CFLIs). Our understanding of CFLI epidemiology has been enhanced by molecular detection methods, particularly polymerase chain reaction (PCR) testing. PCR has not only improved detection of previously known viruses, but within the last decade has resulted in the detection of many divergent novel respiratory virus species. Human rhinovirus (HRV) infections cause nearly all CFLIs and they can be responsible for asthma and chronic obstructive pulmonary disease exacerbations. HRVs are co-detected with other respiratory viruses in statistically significant patterns, with HRVs occurring in the lowest proportion of co-detections, compared to most other respiratory viruses. Some recently identified rhinoviruses may populate an entirely new putative HRV species; HRV C. Further work is required to confirm a causal role for these newly identified viruses in CFLIs. The burden of illness associated with CFLIs is poorly documented, but where data are available, the impact of CFLIs is considerable. Individual infections, although they do not commonly result in more severe respiratory tract illness, are associated with substantial direct and indirect resource use. The product of frequency and burden for CFLIs is likely to be greater in magnitude than for any other respiratory syndrome, but further work is required to document this. Our understanding of the viral causes of CLFIs, although incomplete, has improved in recent years. Documenting burden is also an important step in progress towards improved control and management of these illnesses.

Human rhinoviruses: the cold wars resume

Background

Human rhinoviruses (HRVs) are the most common cause of viral illness worldwide but today, less than half the strains have been sequenced and only a handful examined structurally. This viral super-group, known for decades, has still to face the full force of a molecular biology onslaught. However, newly identified viruses (NIVs) including human metapneumovirus and bocavirus and emergent viruses including SARS-CoV have already been exhaustively scrutinized. The clinical impact of most respiratory NIVs is attributable to one or two major strains but there are 100+ distinct HRVs and, because we have never sought them independently, we must arbitrarily divide the literature's clinical impact findings among them. Early findings from infection studies and use of inefficient detection methods have shaped the way we think of ‘common cold’ viruses today.

Objectives

To review past HRV-related studies in order to put recent HRV discoveries into context.

Results

HRV infections result in undue antibiotic prescriptions, sizable healthcare-related expenditure and exacerbation of expiratory wheezing associated with hospital admission.

Conclusion

The finding of many divergent and previously unrecognized HRV strains has drawn attention and resources back to the most widespread and frequent infectious agent of humans; providing us the chance to seize the advantage in a decades-long cold war.

High prevalence of human enterovirus a infections in natural circulation of human enteroviruses

Human enterovirus (HEV) infections can be asymptomatic or cause only mild illness; recent evidence may implicate HEV infection in type 1 diabetes mellitus and myocarditis. Here, we report the molecular characterization of HEV obtained in serial monthly collections from healthy Norwegian infants. A total of 1,255 fecal samples were collected from 113 healthy infants beginning at age 3 months and continuing to 28 months. The samples were analyzed for HEV nucleic acid by real-time PCR. Fifty-eight children (51.3%) had HEV infections. One hundred forty-five positive samples were typed directly by nucleotide sequencing of the VP1 region. HEV-A was detected most frequently, with an overall prevalence of 6.8%. HEV-B was present in 4.8% of the samples and HEV-C in only 0.2% of the samples. No poliovirus or HEV-D group viruses were detected. Twenty-two different serotypes were detected in the study period: the most common were EV71 (14.5%), CAV6 (10.5%), CAV4 (8.9%), E18 (8.9%), and CBV3 (7.3%). These findings suggest that the prevalence of HEV infections in general, and HEV-A infections in particular, has been underestimated in epidemiological studies based on virus culture.

Longitudinal observation of enterovirus and adenovirus in stool samples from Norwegian infants with the highest genetic risk of type 1 diabetes

BACKGROUND

Enterovirus and adenovirus are common in infancy, causing mostly asymptomatic infections. However, even an asymptomatic infection may be associated with increased risk of development of certain chronic non-infectious diseases, as has been suggested for enterovirus and type 1 diabetes. Data on occurrence and course of the infections in infancy are therefore important for designing effective approaches towards study of the association.

OBJECTIVES

To estimate the frequency of enterovirus and adenovirus infections in Norwegian infants, to evaluate the duration of the infections, to investigate their association with symptoms, and to establish a robust procedure that will be used to study the association between these viruses and the development of auto-immunity leading to type 1 diabetes.

STUDY DESIGN

Parents of infants, recruited for a study on environmental triggers of type 1 diabetes, submitted monthly samples of infant faeces, as well as information on symptoms of infection. The samples were analysed for enterovirus and adenovirus using quantitative real-time PCR, and enterovirus-positive samples were sequenced.

RESULTS

Enteroviruses were found in 142/1,255 (11.3%), and adenoviruses in 138/1,255 (11.0%) of stool samples. Approximately half of the infants were exposed to these viruses at least once during the first year of observation (period 3-14 months of age). The presence of adenovirus was associated with fever and with symptoms of cold but not with diarrhoea and vomiting. The enterovirus positivity was not associated with any symptoms.

CONCLUSIONS

The prevalence of enterovirus and adenovirus in longitudinally obtained faecal samples from infants is sufficiently high to enable studies of their association with chronic diseases. The present protocol for evaluating exposure to these viruses is well suited for large-scale efforts aimed at assessing possible long-term consequences, particularly in relation to type 1 diabetes.

My role in the discovery and classification of the enteroviruses

The enteroviruses constitute one of the genera of the picornavirus family. The genus includes the polioviruses, the coxsackieviruses, and the echoviruses of humans, plus a number of enteroviruses of lower animals (e.g. monkeys, cattle, pigs, mice). Over 100 serotypes are recognized, of which the first to be discovered were the polioviruses. It was my good fortune to have been a scientist during the golden age of virology, when new techniques were being introduced into the field. These often led to the discovery of new viruses. This article details the isolation of the enteroviruses, their recognition as a separate genus of Picornaviridae, and my role in the process. Poliovirus, the most hazardous of the group, is almost gone from the world, but the other enteroviruses will be with us for some time. Several members of the Committee dealing with these agents--Enders,Sabin, Dalldorf, Syverton--have passed on, but the work of this Committee to which I was privileged to contribute will live long.

Infective respiratory exacerbations in young adults with cystic fibrosis: role of viruses and atypical microorganisms

Thirty six adults with cystic fibrosis were studied over one year to determine the incidence of infection with respiratory viruses and atypical organisms. Nineteen patients entered the study during an acute exacerbation of respiratory symptoms with an increase in purulent sputum production, cough, or breathlessness accompanied by a fall in FEV1 (group 1); 17 patients entered when they were stable both clinically and in terms of lung function values (group 2). Group 1 patients had a mean of 2.6 (range 1-4) infective exacerbations during the year and group 2 patients a mean of 1.1 (0-2) exacerbations. Eleven patients developed serological evidence of viral (influenza virus A and B, cytomegalovirus, human rhinovirus 2, adenovirus) or Mycoplasma pneumoniae infection. There was no difference in seroconversion rates between group 1 (five patients) and group 2 (six patients). There was a weak association between viral seroconversion and the isolation of Pseudomonas aeruginosa from sputum, though this was not significant.

Evaluation of mixed cell types and 5-iodo-2'-deoxyuridine treatment upon plaque assay titers of human enteric viruses

Four continuous cell lines, BGM, L-132, HEL-299, and RD, were compared both when cultured separately and as mixtures for use in plaque assay titrations of human adenovirus 1 and six human enterovirus serotypes. The effect of incubating these cell cultures in media containing 5-iodo-2'deoxyuridine (IDU) prior to inoculation with virus was also studied. The use of mixed-cell cultures revealed cell line-dependent synergistic effects as well as inhibitory effects. These effects were strongly virus dependent. In particular, enterovirus 69 did not form plaques on any of the four cell lines when cultured independently. However, it did form plaques on nearly all of the cell lines when cultured as mixtures. Contrary to this effect, when BGM cells were used in combination with the other cell lines, plaque counts for adenovirus 1 were greatly reduced. The effect of IDU pretreatment was also virus and cell line specific and enabled some viruses to form plaques on cell lines when they otherwise would not. Overall, IDU pretreatment resulted in an approximate twofold increase in plaque titers over those obtained without treatment.

Association of respiratory viral infections with pulmonary deterioration in patients with cystic fibrosis

In a two-year prospective study, we examined the effect of respiratory viral infections on pulmonary function in 49 patients with cystic fibrosis (mean age, 13.7 years). Nineteen normal siblings (mean age, 14) served as controls. Subjects were assessed quarterly and at the time of any respiratory illness. Each assessment included nasal washes for viral isolation and blood drawing for respiratory viral serologic studies. Pulmonary-function tests were performed at least twice yearly. Respiratory illnesses were reported significantly more often in the patients (3.7 per year) than in the normal siblings (1.7 per year), although the frequency of proved viral infections (1.67 per year) was identical. In the patients with cystic fibrosis significant correlations (P less than 0.0001) were found between the annual incidence of viral infections and every measure of disease progression in the two-year period, including the rate of decline of the Shwachman score (r = 0.71), the percentage of ideal weight for height (r = 0.80), the forced vital capacity (r = 0.85), the forced expiratory volume in the first second (r = 0.84), the forced midexpiratory flow rate (r = 0.68), and the frequency (r = 0.53) and duration (r = 0.84) of hospitalizations for respiratory exacerbations. We conclude that frequency of viral respiratory infections is closely associated with pulmonary deterioration in patients with cystic fibrosis.

Microbial causes of neonatal conjunctivitis

We assessed the microbial causes of neonatal conjunctivitis by comparing 55 infants with purulent conjunctivitis and 60 healthy control infants. A mean of greater than 5 leukocytes per 1000X microscopic field was seen in Gram-stained smears obtained from the more inflamed eye in 77% of 30 untreated patients but none of 57 controls. Pathogens isolated more often from untreated patients than from controls included Haemophilus spp. (17% vs 2%, P = 0.01), Staphylococcus aureus (17% vs 2%, P = 0.01), Chlamydia trachomatis (14% vs 0%, P = 0.01), enterococci (8% vs 0%, P = 0.05), and Streptococcus pneumoniae (11% vs 2%, P = 0.06). One or more of these pathogens were isolated from the conjunctivae in 58% of patients and 5% of controls (P less than 0.001). Bacterial morphology seen on smear correlated with the pathogens cultured. Isolation of Haemophilus spp. or S. pneumoniae was associated with dacryostenosis. We conclude that several microbial pathogens are implicated in neonatal conjunctivitis. These organisms have differing susceptibilities to antimicrobial agents, so culture and sensitivity testing are required as a guide to therapy.

Sampling strategy for detecting viruses in a sewage treatment plant

A study of pollutant flows was carried out at a wastewater treatment plant in Nancy, France, which used activated-sludge treatment. To carry out observation of hourly flow variation, a sampling strategy needs to be defined. A comparison between two methods of sampling was conducted: dip samples every 2 h over a period of 24 h and one 24-h composite sample were taken from raw and treated wastewater and then analyzed for enteroviruses, fecal coliforms, chemical oxygen demand, biochemical oxygen demand, and suspended solids. The results showed that the hourly variations of these pollutants in the effluents are in good agreement with expectations based upon the customers' usage and the characteristics of the wastewater network. Significant correlations were found between all tested parameters and enteroviruses in raw wastewater. After biological treatment, no correlation remained in treated wastewater between viruses and other parameters. As for the two sampling methods, a rather good representation of the daily load was given by the composite mode of sampling as concerns physicochemical and microbiological parameters. Biological treatment removed an average of 83% of viruses.

Enzyme-linked immunosorbent assay for detection and identification of coxsackieviruses A

Coxsackieviruses A are known to cause a wide range of human disease processes. However, because many coxsackieviruses A present in clinical specimens do not produce a recognizable cytopathic effect in readily available tissue culture systems, infections with coxsackieviruses A are often difficult to diagnose. We have thus developed enzyme-linked immunosorbent assay (ELISA) systems for the detection and serotyping of coxsackievirus A antigens. The assays consist of a double-antibody ELISA which utilizes type-specific monkey and mouse coxsackievirus antisera. Although some cross-reactivity was noted, the ELISA systems correctly identified the serotypes of 22 to 23 coxsackievirus A complement fixation antigens available for testing. Testing of tissue culture fluids revealed that antigen could often be detected by ELISA before the appearance of a cytopathic effect. In addition, the infecting coxsackievirus A antigen could be unequivocally identified in 8 of 11 stool specimens obtained from patients with coxsackievirus A infections. The ELISA system might thus represent an important tool in the diagnosis and study of coxsackievirus A infections.

A survey of virus infections of the respiratory tract of cattle and their association with disease

A total of 1590 caves were investigated between May 1972 and December 1975. Twenty-two per cent were treated for respiratory disease and 2 . 5% died of pneumonia. Almost 80% of the respiratory illness occurred in six sharp outbreaks. Samples of virology were collected routinely from 127 healthy calves and from 354 calves treated for respiratory signs and comprised 1143 nasopharyngeal swabs and 1069 sera. Virus infections were detected on 540 occasions including 135 by parainfluenzavirus type 3 (Pi-3), 78 by respiratory syncytial virus (RSV), 103 by rhinovirus, 49 by bovine virus diarrhoea virus (BVDV), 29 by adenoviruses, 53 by reoviruses and 88 by enteroviruses. The seasonal and age distribution of infections differed between viruses. Only infections by RSV, Pi-3 and BVDV were significantly associated with disease.

A study of infections and illnesses in a day nursery based on inclusion-bearing cells in the urine and infectious agent in faeces, urine and nasal secretion

During an epidemic-free period of nearly 2 years infections and illnesses were followed in a group of small children (2-3 1/2 years) in a day nursery. The incidence of illness was fairly low, 6.3 per child and year. The viral infections were followed by means of the inclusion reaction in the urine and isolation of virus, and the bacterial by culture of nasal secretion. In 60% of the cases the viral infection was accompanied by illness. In 57 cases of illness there were 27 (47%) with merely virus and/or inclusion reaction, 8 (14%) in which bacteria alone were discovered, and 22 (39%) with both. The viral infections were the decisive ones in about 80% of the illnesses. Enteric respiratory viruses of 10 types were detected. 16 (73%) of the 22 children had such an infection on at least one occasion, and spread within the group occurred on infection with echovirus 9, coxsackievirus B4 and reovirus. Enteric viruses accounted for 29% of the viral infections. Streptococci and Mycoplasma pneumoniae played no part in the bacterial infections, which were entirely dominated by pneumococci. Cytomegaloviruria was found in 13 (72%) of 18 children examined. No spread was detected within the group. Rotavirus was on no occasion found in faeces.

A study of acute respiratory disease in the community of Port Chalmers. II. Influenza A/Port Chalmers/1/73: intrafamilial spread and the effect of antibodies to the surface antigens

During the first year of a study of respiratory disease in the semi-isolated community of Port Chalmers, New Zealand, an epidemic of clinical influenza occurred from which the variant influenza A/Port Chalmers/1/73 (H3N2) was isolated. Within a selected group of 26 families, 59 (46%) members had clinical or laboratory evidence of infection. During intrafamilial spread the infection frequency was highest for school-aged children (77%), followed by female adults (67%), infants (64%) and male adults (41%). The index infection in each family was a school-age child on 10 occasions, suggesting the role of this age group in the transmission of influenza A in this community. The secondary attack rate (SAR) of 58.3% was higher than expected. In sera taken before the 1973 epidemic, 59% of family members had detectable HI antibody and 25% NI antibody to A/England/42/72 while 38% had detectable HI antibody and 8% NI antibody to A/Port Chalmers/1/73. The relation between pre-existing antibody and infection frequency is discussed.

Infections in preschool children in group day care

Viral and bacterial infections in 20 children under 3 years of age were studied in a day centre for 12 weeks. Febrile illnesses were found on one occasion in each of 11 children but no serious infection occurred. Pneumococci types 6, 9, or 19 were isolated from all children but more often from those with rhinitis or cough. The individual child had an average of 2 viral infections. Adenovirus types 1, 2, 5, coxsackievirus type B5, herpes simplex virus or respiratory syncytial virus was isolated from 12% of the oropharynx swabs and 40% of the fecal specimens. When a virus was first isolated from the oropharynx, the children were asymptomatic or had only rhinitis in 73% of the cases which might indicate that the dismissing of symptomatic children is of limited value in controlling the spread of infections in a day care centre. Cytomegalovirus was recovered from 22% of the urine specimens. Carrier frequency of cytomegalovirus was 23% in 40 other children attending one of 13 different day care centers. Because asymptomatic cytomegalovirus infections apparently occur frequently among small children in Sweden, it seems reasonable not to take pronounced measures of isolating the children in the relatively few recognized cases of cytomegalovirus infections.

Sequelae of central-nervous-system enterovirus infections

The long-term effects of central-nervous-system enterovirus infections were examined in a controlled follow-up study of 19 children 2 1/2 to eight years of age who had been hospitalized with documented enterovirus infection 17 to 67 months before evaluation. Assessment included medical history, physical and neurologic examination, psychologic testing, and speech and hearing evaluation. Three children (16 per cent) had definite neurologic impairment, five (26 per cent) had possible impairment, and 11 (58 per cent) were free of detectable abnormalities. Children whose illness occurred during the first year of life, when compared to controls, were found to have significantly smaller mean head circumference (50.6 vs. 51.6 cm, P less than 0.033), significantly lower mean I.Q. (97 vs 115, P less than 0.007), and depressed languange and speech skills. Children whose illness occurred after the first year of life were not different from their controls. Children whith central-nervous-system enterovirus infection may have neurologic impairment when infection occurs in the first year of life.

Ecology of enteroviruses in tropics. I. Circulation of enteroviruses in healthy infants in tropical urban area

A continuing surveillance on enterovirus infection in healthy infants was conducted from October 1971 through February 1973 in urban areas in Ghana, West Africa. About 40 infants were visited in every two months for collection of faecal specimens and examined for infection. Enteroviruses were recovered in tissue culture. The overall isolation rate of enteroviruses was approximately 44%, and there was no seasonal difference between rainy and dry seasons. The rate of virus isolation in urban areas was significantly higher than in rural areas. Within the urban areas, however, no difference in the rate of virus isolation was detected between densely populated and sparsely populated areas. The results of virus identification revealed that all three types of Poliovirus, many types of Echovirus and a few Coxsackieviruses were isolated during the course of the study. It was observed that improvement of sanitary facilities decreased the frequency of virus infection among infants, but the condition of water supply did not influence the virus infection rate. Neither the age of infants nor the size of siblings showed any relation to the virus isolation rate. It was suggested from the results that many types of enteroviruses have been circulation continuously in the tropical urban community throughout the year.