Transmission of viral respiratory infections in the home

Winter peak of respiratory syncytial virus in Islamabad

A study was carried out on 391 cases of bronchiolitis and pneumonia from different paediatric units in Rawalpindi/Islamabad, Pakistan. A clear winter spike of respiratory syncytial virus (RSV) was noted. It was found that there was a substantial increase of 30-50% in the positivity of RSV from December to February.

Illness transmission in the home: a possible role for alcohol-based hand gels

OBJECTIVES

The widespread use of child care has altered the epidemiology of respiratory and gastrointestinal (GI) infection in the community. Our primary objective was to measure transmission of respiratory and GI illnesses among families with children enrolled in child care. We also sought to examine potential predictors of reduced illness transmission in the home in a secondary analysis.

METHODS

We performed an observational, prospective cohort study to determine transmission rates for respiratory and GI illnesses within families with at least 1 child between 6 months and 5 years of age enrolled in child care. A survey about family beliefs and practices was mailed at the beginning of the study. Symptom diaries were provided for families to record the timing and duration of respiratory and GI illnesses. To ensure the accuracy of symptom diaries, biweekly telephone calls were performed to review illnesses recorded by participants. Families with > or =4 weeks of data recorded were included in the analysis. Families were recruited from 5 pediatric practices in the metropolitan Boston area. Of 261 families who agreed to participate in the study, 208 were available for analysis. Secondary transmission rates for respiratory and GI illnesses were measured as illnesses per susceptible person-month.

RESULTS

We observed 1545 respiratory and 360 GI illnesses in 208 families from November 2000 to May 2001. Of these, 1099 (71%) respiratory and 297 (83%) GI illnesses were considered primary illnesses introduced into the home. The secondary transmission rates for respiratory and GI illnesses were 0.63 and 0.35 illnesses per susceptible person-month, respectively. Only two thirds of respondents correctly believed that contact transmission was important in the spread of colds, and fewer than half believed that it was important in the spread of stomach flus. Twenty-two percent of respondents reported use of alcohol-based hand gels all, most, or some of the time; 33% reported always washing their hands after blowing or wiping a nose. In multivariate models, use of alcohol-based hand gels had a protective effect against respiratory illness transmission in the home.

CONCLUSIONS

In homes with young children enrolled in child care, illness transmission to family members occurs frequently. Alcohol-based hand gel use was associated with reduced respiratory illness transmission in the home.

Protecting health care workers from SARS and other respiratory pathogens: a review of the infection control literature

BACKGROUND

Severe Acute Respiratory Syndrome (SARS) was responsible for outbreaks in Canada, China, Hong Kong, Vietnam, and Singapore. SARS focused attention on the adequacy of and compliance with infection control practices in preventing airborne and droplet-spread transmission of infectious agents.

METHODS

This paper presents a review of the current scientific knowledge with respect to the efficacy of personal protective equipment in preventing the transmission of respiratory infections. The effectiveness of infection control policies and procedures used in clinical practice is examined.

RESULTS

Literature searches were conducted in several databases for articles published in the last 15 years that related to infection control practices, occupational health and safety issues, environmental factors, and other issues of importance in protecting workers against respiratory infections in health care settings.

CONCLUSION

Failure to implement appropriate barrier precautions is responsible for most nosocomial transmissions. However, the possibility of a gradation of infectious particles generated by aerosolizing procedures suggests that traditional droplet transmission prevention measures may be inadequate in some settings. Further research is needed in this area.

Animal pneumoviruses: molecular genetics and pathogenesis

Pneumoviruses are single-stranded, negative-sense, nonsegmented RNA viruses of the family Paramyxoviridae, subfamily Pneumovirinae, and include pathogens that infect humans (respiratory syncytial virus and human metapneumovirus), domestic mammals (bovine, ovine, and caprine respiratory syncytial viruses), rodents (pneumonia virus of mice), and birds (avian metapneumovirus). Among the topics considered in this review are recent studies focused on the roles of the individual virus-encoded components in promoting virus replication as well as in altering and evading innate antiviral host defenses. Advances in the molecular technology of pneumoviruses and the emergence of recombinant pneumoviruses that are leading to improved virus-based vaccine formulations are also discussed. Since pneumovirus infection in natural hosts is associated with a profound inflammatory response that persists despite adequate antiviral therapy, we also review the recent experimental treatment strategies that have focused on combined antiviral, anti-inflammatory, and immunomodulatory approaches.

Effect of antibacterial home cleaning and handwashing products on infectious disease symptoms: a randomized, double-blind trial

BACKGROUND

Despite the widespread household use of cleaning and personal hygiene products containing antibacterial ingredients, their effects on the incidence of infectious disease symptoms have not been studied.

OBJECTIVE

To evaluate the effect of antibacterial cleaning and handwashing products for consumers on the occurrence of infectious disease symptoms in households.

DESIGN

Randomized, double-blind clinical trial.

SETTING

Northern Manhattan inner-city neighborhood, New York.

PARTICIPANTS

238 primarily Hispanic households (1178 persons) that included at least one preschool-age child.

INTERVENTIONS

Households were randomly assigned to use either antibacterial or nonantibacterial products for general cleaning, laundry, and handwashing. All products were commercially available, but the packaging was blinded and the products were provided free to participants.

MEASUREMENTS

Hygiene practices and infectious disease symptoms were monitored by weekly telephone calls, monthly home visits, and quarterly interviews for 48 weeks.

RESULTS

Symptoms were primarily respiratory: During 26.2% (717 of 2736) of household-months, 23.3% (640 of 2737) of household-months, and 10.2% (278 of 2737) of household-months, one or more members of the household had a runny nose, cough, or sore throat, respectively. Fever was present during 11% (301 of 2737) of household-months, vomiting was present in 2.2% (61 of 2737), diarrhea was present in 2.5% (69 of 2737), and boils or conjunctivitis were present in 0.77% (21 of 2737). Differences between intervention and control groups were not significant for any symptoms (all unadjusted and adjusted relative risks included 1.0) or for numbers of symptoms (overall incidence density ratio, 0.96 [95% CI, 0.82 to 1.12]).

CONCLUSIONS

The tested antibacterial products did not reduce the risk for symptoms of viral infectious diseases in households that included essentially healthy persons. This does not preclude the potential contribution of these products to reducing symptoms of bacterial diseases in the home.

Transmission of influenza: implications for control in health care settings

Annual influenza epidemics in the United States result in an average of >36,000 deaths and 114,000 hospitalizations. Influenza can spread rapidly to patients and health care personnel in health care settings after influenza is introduced by visitors, staff, or patients. Influenza outbreaks in health care facilities can have potentially devastating consequences, particularly for immunocompromised persons. Although vaccination of health care personnel and patients is the primary means to prevent and control outbreaks of influenza in health care settings, antiviral influenza medications and isolation precautions are important adjuncts. Although droplet transmission is thought to be the primary mode of influenza transmission, limited evidence is available to support the relative clinical importance of contact, droplet, and droplet nuclei (airborne) transmission of influenza. In this article, the results of studies on the modes of influenza transmission and their relevant isolation precautions are reviewed.

Epidemiology of viral respiratory infections

Acute respiratory tract infections are the most common illnesses in all individuals, regardless of age or gender. Epidemiologic surveys and community-based studies conducted since the beginning of the 20th century have determined the rates of illness and the pathogens involved in such infections. These studies have shown that rhinoviruses cause the great majority of these respiratory illnesses, and their findings have examined the means of transmission of respiratory illness. More recently, advances in diagnostic techniques have enabled more complete identification of the viruses involved in respiratory infections, which has aided in the ability to direct specific therapeutic agents at the causative pathogens.

Chaotic mixing deep in the lung

Our current understanding of the transport and deposition of aerosols (viruses, bacteria, air pollutants, aerosolized drugs) deep in the lung has been grounded in dispersive theories based on untested assumptions about the nature of acinar airflow fields. Traditionally, these have been taken to be simple and kinematically reversible. In this article, we apply the recently discovered fluid mechanical phenomenon of irreversible low-Reynolds number flow to the lung. We demonstrate, through flow visualization studies in rhythmically ventilated rat lungs, that such a foundation is false, and that chaotic mixing may be key to aerosol transport. We found substantial alveolar flow irreversibility with stretched and folded fractal patterns, which lead to a sudden increase in mixing. These findings support our theory that chaotic alveolar flow--characterized by stagnation saddle points associated with alveolar vortices--governs gas kinematics in the lung periphery, and hence the transport, mixing, and ultimately the deposition of fine aerosols. This mechanism calls for a rethinking of the relationship of exposure and deposition of fine inhaled particles.

Epidemiology of viral respiratory infections

Acute respiratory tract infections are the most common illnesses in all individuals, regardless of age or gender. Epidemiologic surveys and community-based studies conducted since the beginning of the 20th century have determined the rates of illness and the pathogens involved in such infections. These studies have shown that rhinoviruses cause the great majority of these respiratory illnesses, and their findings have examined the means of transmission of respiratory illness. More recently, advances in diagnostic techniques have enabled more complete identification of the viruses involved in respiratory infections, which has aided in the ability to direct specific therapeutic agents at the causative pathogens.

An epidemic of inhalation anthrax, the first in the twentieth century: I. Clinical features. 1960

Acute respiratory tract infections are the most common illnesses in all individuals, regardless of age or gender. Epidemiologic surveys and community-based studies conducted since the beginning of the 20th century have determined the rates of illness and the pathogens involved in such infections. These studies have shown that rhinoviruses cause the great majority of these respiratory illnesses, and their findings have examined the means of transmission of respiratory illness. More recently, advances in diagnostic techniques have enabled more complete identification of the viruses involved in respiratory infections, which has aided in the ability to direct specific therapeutic agents at the causative pathogens.

The role of the home environment in the transmission of infectious diseases

The purpose of this paper is to examine current health care literature (1980-2000) regarding the microbiology of the home environment, to summarize evidence of transmission within the home, and to assess effectiveness of cleaning practices and products. The home environment, particularly the kitchen and bathroom, serves as a reservoir of large numbers of microorganisms, particularly Enterobacteriacae, and infectious disease transmission has been demonstrated to occur in 6-60% of households in which one member is ill. Current food preparation and cleaning practices provide multiple opportunities for intra-household member spread. Routine cleaning is often sufficient, but in cases of household infection, may not adequately reduce environmental contamination. The effectiveness of disinfectants varies considerably and depends on how they are used as well as their intrinsic efficacy. The behavioral aspects of infection prevention in the home (e.g., foodhandling and cleaning practices) warrant increased public attention and education.