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Danville hospital has 47 employees treated for scabies
By Pam G. Dempsey
Friday, September 29, 2006
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DANVILLE – An exposure to scabies has affected 47 Provena United Samaritans Medical Center personnel, a hospital official said.
The employees were exposed to the skin mite after an infected patient was treated at the hospital sometime between Sept. 7 and 18, said hospital spokeswoman Gretchen Wesner. The hospital employs 850 people.
“As soon as we had confirmation that’s what it was, the patient was isolated and we notified all the departments that there was this case,” Wesner said.
Scabies is a skin infestation of a microscopic insect that causes pimple-like skin irritations and intense itching, according to the Centers for Disease Control and Prevention Web site. Scabies is spread by prolonged, direct skin-to-skin contact with an infected person. It can spread rapidly under crowded conditions where there is frequent skin-to-skin contact such as hospitals, nursing homes and child-care facilities, the CDC reports.
Each hospital department was given information on the symptoms, Wesner said.
Provena set up a clinic for the exposed employees and their families.
Anyone suspected of exposure and symptoms was evaluated and treated, she said. The employees were sent home for 48 hours, although the CDC recommends that health care staff be off for 24 hours if exposed, Wesner said.
When the employees returned to work, they were evaluated again, she said.
As of now, 12 employees are still off from work.
“We did want to ensure that family members were also treated as necessary,” Wesner said. “The hospital is paying for the cost of treatment for the employees and their families.”
Scabies is treated with a topical ointment, Wesner said.
She could not recall another mass case of scabies at the hospital during the past six years.
“What we’re trying to do is to prevent something like this occurring again,” Wesner said. “We’re reviewing with our staff all proper precautions that they should take with patients and what they can do to protect themselves as well as they can.”
Vermilion County Health Department officials said an increase in scabies cases does not require a report to the community such as salmonella cases.
“It’s out in the community all the time,” said Sherrie Shoemaker, the county’s coordinator for communicable diseases. “There’s always cases of scabies. They kind of run in cycles.”
In situations where there’s a large cluster of scabies cases, county officials work with the facility, such as schools and hospitals, to see that staff is taking the necessary precautions.
The mites cannot survive without a human host for more than three days, Shoemaker said. She recommends vacuuming daily and washing clothes and bedsheets in hot water to prevent its spread.
Shoemaker also recommends that if anyone has been exposed or suspected they’ve contracted scabies to contact their physician and avoid close contact with anyone until they’ve been treated
Fri 29 Sep 2006 6:58 PM ET
WASHINGTON, Sept 29 (Reuters) – Children with flu who are given Tamiflu, Roche AG’s influenza pill, are 53 percent less likely to develop pneumonia than untreated children, the company reported on Friday.
And a second study showed that giving Tamiflu to very sick adults with influenza reduced their risk of death by 71 percent.
The studies, presented at the Interscience Congress on Antimicrobial Agents and Chemotherapy, held in San Francisco, bolster earlier studies that show the drug can prevent the most serious consequences of influenza.
Seasonal flu affects hundreds of millions of people every year. In the United States alone, the Centers for Disease Control and Prevention estimates that flu kills 36,000 people every year and puts up to 200,000 in the hospital.
Around the world, influenza kills between 250,000 and 500,000 people every year. Most of the severe illnesses and deaths are due to pneumonia, sometimes caused by a bacterial or secondary infection.
Tamiflu, or oseltamivir, made by Roche under license from Gilead Sciences , can reduce the severity of infection, as can a rival drug, Relenza, made by GlaxoSmithKline . Older flu drugs no longer work well and are not recommended.
Researchers studied the health insurance records of more than 15,000 children aged one to 12. About 2.6 percent of them came down with pneumonia.
Children who received Tamiflu within one day of an influenza diagnosis were 53 percent less likely to develop pneumonia, compared with children who were not given the drug.
“This study suggests that early treatment with Tamiflu can have a significant impact on pneumonia, one of flu’s most serious complications, which takes a considerable toll on children,” said Dominick Iacuzio, medical director at Roche.
A second study presented at the same conference showed Tamiflu could reduce deaths in severely ill adults with flu. “Treatment of infected adults was associated with a 71 per cent reduction in mortality,” the company said.
Dr. Allison McGeer and colleagues at Mount Sinai Hospital in Toronto, Canada studied 512 patients admitted to hospital with influenza.
They said 84 percent were treated with antibiotics, which are aimed at stopping bacterial infections, and 32 percent got antivirals, mostly Tamiflu, but the older drug amantadine was also administered to a few.
“Of all adult patients, 6.4 percent of patients died and these deaths were attributed to influenza,” Roche said.
But those given an antiviral were much less likely to die.
Many countries are stocking up on Tamiflu because of the risk of H5N1 avian flu. It mainly affects birds but experts fear it could mutate into a strain capable of killing millions of people in a global pandemic. It has killed 148 people out of 251 infected in 10 countries since 2003.
Tamiflu is now routinely given to bird flu victims and doctors say if given quickly enough, it appears to save lives.
The CDC says the best protection against flu is an annual vaccine, but that does not prevent influenza perfectly, especially in older adults, and many people fail to get immunized.
Ticking Time Bomb: Prisons Unprepared for Flu Pandemic,
Says New SLU Research
As the fear of an impending avian flu pandemic is compelling hospitals, businesses and cities to develop preparedness plans, one of the most potentially dangerous breeding grounds of disease is woefully ill-prepared for a crisis, according to a new study being presented today by researchers at the Institute for Biosecurity.
“There’s a real failure to recognize how important the health status of inmates is to the public health of all of us,” says Rachel Schwartz, Ph.D., a researcher at the Institute for Biosecurity. “Nearly 85 percent of those in jails and prisons will be released within a year. So even if we as a society don’t think protecting them from disease is a priority, prisoners released into the general population pose a real threat to society.”
The research was presented this month at the Correctional Medicine Institute’s 2006 Conference in Baltimore.
There are more than two million prisoners in the United States, making up what Schwartz calls “a highly vulnerable population.”
“There’s a much higher level of disease among prisoners—people with HIV, drug-resistant tuberculosis, hepatitis C and other diseases,” she says.
She adds that 80 percent of inmates come to prison with some sort of illness.
“And once they’re incarcerated, they’re more likely to get other diseases. It makes correctional facilities into ticking time bombs. Many people crowded together, often suffering from diseases that weaken their immune systems, form a potential breeding ground and reservoir for diseases.”
Schwartz and fellow researchers studied research and protocols from the Centers for Disease Control, the World Health Organization and other governments to identify what plans were in place for prisons should an infectious disease break out.
Many of the correctional facilities that Schwartz and colleagues studied have acknowledged they don’t have an adequate plan to deal with a pandemic or similar health crisis. Schwartz says there’s reluctance among government leaders to provide prisoners with medical care, such as flu vaccines.
“The thinking is that there won’t be enough for the general public, and that they should get the shots first,” she says. “We tend to think of all inmates as being violent offenders, but the average length of incarceration is only 48 hours. Many are not convicted criminals, but rather people merely accused of crimes and awaiting trial.
“We know that illness among prisoners will eventually spread and cause illness in society, so we must address this now.”
The solution, says Schwartz, is to spend more energy and money on preparedness. She and fellow researchers developed a plan to educate the judicial and prison systems on ways to prevent the spread of disease, from meticulous hand-washing to appropriate use of quarantine and isolation in prison and jail settings.
The pandemic plans are designed to provide useful information for many kinds of crisis situations, Schwartz says.
“Ideally, they will help authorities prepare and respond to anything from a bird flu breakout to a biological attack. The information is also critical for existing illnesses within prisons, like HIV, not just emerging infections.”
Source: St. Louis University Institute for BioSecurity
Introduction: If you would prefer not having your eyelids droop or your speech slurred or your respiratory muscles go on vacation, read on:
FDA Press Release, 9/29/06: In response to a fourth case of botulism being linked to Bolthouse Farms, Bakersfield, California brand carrot juice, the Food and Drug Administration (FDA) is warning consumers not to drink Bolthouse Farms Carrot Juice, 450 ml and 1 liter plastic bottles, with “BEST IF USED BY” dates of NOV 11 2006 or earlier.
Consumers should discard this product. FDA is also reiterating its advice to consumers to keep carrot juice — including pasteurized carrot juice — refrigerated.
The fourth case of botulism poisoning involves an adult female in Florida who is currently suffering from paralysis. To date, one link between the illness and the consumers appears to be that the juice they drank was not properly refrigerated once it was in the home, which allowed the Clostridium botulinum spores to grow and produce toxin. FDA is investigating other possible links.
Clostridium botulinum is a bacterium commonly found in soil. Under certain conditions these bacteria can produce a toxin that if ingested can result in botulism, a disease that may cause paralysis or death. Cases of botulism from processed food are extremely rare in the U.S.
Symptoms of botulism can include: double-vision, droopy eyelids, altered voice, trouble with speaking or swallowing, and paralysis on both sides of the body that progresses from the neck down, possibly followed by difficulty in breathing. Anyone experiencing these symptoms should seek immediate medical attention.
Adequate refrigeration is one of the keys to food safety and is essential to preventing bacterial growth. Refrigerator temperatures should be no higher than 40°F and freezer temperatures no higher then 0°F. Consumers should check the temperatures occasionally with an appliance thermometer.
Consumers should look for the words “Keep Refrigerated” on juice labels so they know which products must be kept refrigerated. FDA is looking into whether industry’s current juice labels provide clear refrigeration instructions.
FDA Approves Nerve-Poisoning Agents
for Use by Trained Emergency Medical Services Personnel
The U.S. Food and Drug Administration (FDA) today approved Duodote (atropine and pralidoxime chloride injection) for use by trained emergency medical services personnel to treat civilians exposed to life-threatening organophosphorus-containing nerve agents, such as sarin, and insecticides. Duodote is manufactured by Meridian Medical Technologies, Inc., Columbia, Md.
FDA previously approved atropine and pralidoxime chloride injection under the name Antidote Treatment–Nerve Agent Auto-Injector (ATNAA) for military use. Developed by the U.S. Army and manufactured by Meridian Medical Technologies, Inc., ATNAA is not available for use in civilians. ATNAA was approved on Jan. 17, 2002, for use by the military to treat troops who have been exposed to toxic nerve agents that cause loss of muscle control and death from respiratory failure. The two constituent drugs in ATNAA were previously approved for use separately. Atropine autoinjector has been approved for use in adults since 1973, and its use in children and adolescents was approved in June 2003. Pralidoxime was first approved for use in 1964.
“Today’s approval facilitates the stockpiling of the product so that it can be used to treat civilians in an emergency,” said Douglas Throckmorton, M.D., deputy director of FDA’s Center for Drug Evaluation and Research. “The approval contains two caveats: the primary protection against exposure to chemical nerve agents and insecticide poisoning is the wearing of protective clothing; and Duodote may be administered only by well-trained emergency medical personnel.”
The manufacturer will distribute Duodote directly to emergency medical service organizations or their suppliers.
FDA is announcing today that all spinach implicated in the current outbreak has traced back to Natural Selection Foods LLC of San Juan Bautista, California.
This determination is based on epidemiological and laboratory evidence obtained by multiple states and coordinated by the Centers for Disease Control and Prevention. Natural Selection Foods issued a recall of all implicated products on September 15, 2006. Four other companies have issued secondary recalls because they received the recalled product from Natural Selections. See below for a complete list of brand names that are subject of the recalls. Spinach processed by other manufacturers has not been implicated in the outbreak.
FDA, the State of California, the Centers for Disease Control and Prevention and the United States Department of Agriculture continue to investigate the cause of the outbreak. This includes continued inspections and sample collection in facilities, the environment and water, as well as studies of animal management, water use and the environment.
Next Steps
Although the current outbreak may ultimately trace back to a specific field(s), there has been a long history of E. coli O157:H7 outbreaks involving leafy greens from the central California region. Spinach processed by other manufacturers has not been implicated in this outbreak, however, based on discussions with industry, and given the past E. coli O157:H7 outbreaks, FDA and the State of California expect the industry to develop a comprehensive plan which is designed to minimize the risk of another outbreak due to E. coli O157:H7 in spinach grown in central California. While this plan is under development, FDA and the State of California reiterate our previous concerns and advise firms to review their current operations in light of the agency’s guidance for minimizing microbial food safety hazards.
FDA and the State of California have previously expressed serious concern with the continuing outbreaks of foodborne illness associated with the consumption of fresh and fresh-cut lettuce and other leafy greens. After discussions with industry, FDA and the State of California, as part of a longer term strategy, now expect industry to develop a plan to minimize the risk of another outbreak due to E. coli O157:H7 in all leafy greens, including lettuce.
The Grower Shipper Association of Central California, the Produce Marketing Association, the United Fresh Produce Association, and the Western Growers Association, said today, “We are committed to working together as one industry to learn everything we can from this tragedy, and will redouble our efforts to do everything in our power to reduce the potential risk of foodborne illness. As we have in the past, we will work aggressively with the Food and Drug Administration and state regulatory authorities to ensure the industry’s growing and processing practices continue to be based on the very best scientific information available, and that we are doing everything possible to provide the nation with safe and healthy produce.”
Implementation of these plans will be voluntary, but FDA and the State of California are not excluding the possibility of regulatory requirements in the future.
FDA will be holding a public meeting to address the larger issue of food borne illness linked to leafy greens later in the year once the current investigation is complete.
Advice to Retailers, Restaurateurs and the Public
FDA is still reminding the public that Natural Selection Foods has recalled all spinach products under multiple brand names with a date code of October 1 or earlier. There have been four other recalls from different companies because they received Natural Selection Foods spinach. See below for a complete list of brand names that are subject of the recalls.
In order to protect consumers, retailers and restaurateurs should not sell raw spinach or blends that may contain spinach that was processed by Natural Selection Foods and all other brands subject to the recalls.
Consumers are advised that proper storage of fresh produce can affect both quality and safety. To maintain quality of fresh produce, certain perishable fresh fruits and vegetables (like strawberries, lettuce, herbs, and mushrooms) can be best maintained by storing in a clean refrigerator at a temperature of 40° F or below. All produce that is purchased pre-cut or peeled should be refrigerated to maintain both quality and safety.
Many precut, bagged produce items like lettuce are pre-washed. If so, it will be stated on the packaging. This pre-washed, bagged produce can be used without further washing.
Processed spinach (e.g., frozen and canned spinach) is not implicated in this outbreak.
Number of Cases of Infection, Hospitalization and Death
To date, 187 cases of illness due to E. coli O157:H7 infection have been reported to the Centers for Disease Control and Prevention (CDC), including 29 cases of Hemolytic Uremic Syndrome (HUS), 97 hospitalizations and one death.
States Involved and Number of Cases
The 26 affected states are: Arizona (7), California (2), Colorado (1), Connecticut (3) Idaho (4), Illinois (1), Indiana (9), Kentucky (8), Maine (3), Maryland (3), Michigan (4), Minnesota (2), Nebraska (9), Nevada (1), New Mexico (5), New York (11), Ohio (25), Oregon (6), Pennsylvania (9), Tennessee (1), Utah (17), Virginia (2), Washington (3), West Virginia (1), Wisconsin (49), and Wyoming (1). In addition, Canada has one confirmed case.
Comment: The following article which was expeditied for publication by the journal, Emerging Infectious Diseases, provides a convincing argument that all healthcare providers should be using N-95 respirators when caring for patients with the flu. By a logical extension of this argument, this should be the standard and should be incorporated in protocols when planning for the Pandemic Flu outbreak.
Emerging Infectious Diseases
Volume 12, Number 11–November 2006
Perspective
Review of Aerosol Transmission of Influenza A Virus
Raymond Tellier*†
*Hospital for Sick Children, Toronto, Ontario, Canada; and †University of Toronto, Toronto, Ontario, Canada
Abstract
In theory, influenza viruses can be transmitted through aerosols, large droplets, or direct contact with secretions (or fomites). These 3 modes are not mutually exclusive. Published findings that support the occurrence of aerosol transmission were reviewed to assess the importance of this mode of transmission. Compelling evidence in the literature indicates that aerosol transmission of influenza is an important mode of transmission, which has obvious implications for pandemic influenza planning, and in particular for recommendations about the use of N95 respirators as part of personal protective equipment.
Concerns about the likely occurrence of an influenza pandemic in the near future are increasing. The highly pathogenic strains of influenza A (H5N1) virus circulating in Asia, Europe, and Africa have become the most feared candidates for giving rise to a pandemic strain.
Several authors have stated that large-droplet transmission is the predominant mode by which influenza virus infection is acquired (1–3). As a consequence of this opinion, protection against infectious aerosols is often ignored for influenza, including in the context of influenza pandemic preparedness. For example, the Canadian Pandemic Influenza Plan and the US Department of Health and Human Services Pandemic Influenza Plan (4,5) recommend surgical masks, not N95 respirators, as part of personal protective equipment (PPE) for routine patient care. This position contradicts the knowledge on influenza virus transmission accumulated in the past several decades. Indeed, the relevant chapters of many reference books, written by recognized authorities, refer to aerosols as an important mode of transmission for influenza (6–9).
In preparation for a possible pandemic caused by a highly lethal virus such as influenza A (H5N1), making the assumption that the role of aerosols in transmission of this virus will be similar to their role in the transmission of known human influenza viruses would seem rational. Because infection with influenza A (H5N1) virus is associated with high death rates and because healthcare workers cannot as yet be protected by vaccination, recommending an enhanced level of protection, including the use of N95 respirators as part of PPE, is important. Following are a brief review of the relevant published findings that support the importance of aerosol transmission of influenza and a brief discussion on the implications of these findings on pandemic preparedness.
Influenza Virus Aerosols
By definition, aerosols are suspensions in air (or in a gas) of solid or liquid particles, small enough that they remain airborne for prolonged periods because of their low settling velocity. For spherical particles of unit density, settling times (for a 3-m fall) for specific diameters are 10 s for 100 μm, 4 min for 20 μm, 17 min for 10 μm, and 62 min for 5 μm; particles with a diameter <3 μm essentially do not settle. Settling times can be further affected by air turbulence (10,11).
The median diameters at which particles exhibit aerosol behavior also correspond to the sizes at which they are efficiently deposited in the lower respiratory tract when inhaled. Particles of >6-μm diameter are trapped increasingly in the upper respiratory tract (12); no substantial deposition in the lower respiratory tract occurs at >20 μm (11,12). Many authors adopt a size cutoff of <5 μm for aerosols. This convenient convention is, however, somewhat arbitrary, because the long settling time and the efficient deposition in the lower respiratory tract are properties that do not appear abruptly at a specific diameter value. Certainly, particles in the micron or submicron range will behave as aerosols, and particles >10–20 μm will settle rapidly, will not be deposited in the lower respiratory tract, and are referred to as large droplets (10–12).
Coughing or sneezing generates a substantial quantity of particles, a large number of which are <5–10 μm in diameter [reviewed in (10)]. In addition, particles expelled by coughing or sneezing rapidly shrink in size by evaporation, thereby increasing the number of particles that behave as aerosols. Particles shrunken by evaporation are referred to as droplet nuclei (10–12). This phenomenon affects particles with a diameter at emission of <20 μm, and complete desiccation would decrease the diameter to a little less than half the initial diameter (10). Droplet nuclei are hygroscopic. When exposed to humid air (as in the lungs), they will swell back. One would expect that inhaled hygroscopic particles would be retained in the lower respiratory tract with greater efficiency, and this hypothesis has been confirmed experimentally (11,12). Aerosols, though heavily diluted, remain airborne and thus can be carried over large distances, which may create a potential for long-range infections. The occurrence of long-range infections is affected by several other factors. These include the infectious dose, the amount of infectious particles produced, the duration of shedding of the infectious agent, and the persistence of the agent in the environment (11). Inferring an absence of aerosols because long-range infections are not frequently observed is incorrect.
Humans acutely infected with influenza A virus have a high virus titer in their respiratory secretions, which makes generation of virus aerosols possible. The viral titer measured in nasopharyngeal washes culminates on approximately day 2 or 3 after infection and can reach up to 107 50% tissue culture infective dose (TCID50)/mL (13,14). The persistence of the infectivity of influenza virus in aerosols has been studied in the laboratory. In experiments that used homogeneous aerosolized influenza virus suspensions (mean diameter 6 μm), virus infectivity (assessed by in vitro culture) at a fixed relative humidity undergoes an exponential decay; this decay is characterized by very low death rate constants, provided that the relative humidity was in the low range of 15%–40% (15,16). These results are consistent with those of an older study (admittedly performed in a more rudimentary manner) in which infectious influenza viruses in an aerosol could be demonstrated for up to 24 h by using infection in mice as a detection method, provided that the relative humidity was 17%-24% (17). In all these studies, the decay of virus infectivity increased rapidly at relative humidity >40%. The increased survival of influenza virus in aerosols at low relative humidity has been suggested as a factor that accounts for the seasonality of influenza (15,16). The sharply increased decay of infectivity at high humidity has also been observed for other enveloped viruses (e.g., measles virus); in contrast, exactly the opposite relationship has been shown for some nonenveloped viruses (e.g., poliovirus) (11,15,16).
Experimental Influenza Infection
Experimental infection studies permit the clear separation of the aerosol route of transmission from transmission by large droplets. Laboratory preparation of homogeneous small particle aerosols free of large droplets is readily achieved (13,18). Conversely, transmission by large droplets without accompanying aerosols can be achieved by intranasal drop inoculation (13).
Influenza infection has been documented by aerosol exposure in the mouse model, the squirrel monkey model, and human volunteers (12,13,17–19). Observations made during experimental infections with human volunteers are particularly interesting and relevant. In studies conducted by Alford and colleagues (18), volunteers were exposed to carefully titrated aerosolized influenza virus suspensions by inhaling 10 L of aerosol through a face mask. The diameter of the aerosol particles was 1 μm–3 μm. Demonstration of infection in participants in the study experiment was achieved by recovery of infectious viruses from throat swabs, taken daily, or by seroconversion, i.e., development of neutralizing antibodies. The use of carefully titrated viral stocks enabled the determination of the minimal infectious dose by aerosol inoculation. For volunteers who lacked detectable neutralizing antibodies at the onset, the 50% human infectious dose (HID50) was 0.6–3.0 TCID50, if one assumes a retention of 60% of the inhaled particles (18). In contrast, the HID50 measured when inoculation was performed by intranasal drops was 127–320 TCID50 (13). Additional data from experiments conducted with aerosolized influenza virus (average diameter 1.5 μm) showed that when a dose of 3 TCID50 was inhaled, ≈1 TCID50 only was deposited in the nose (12). Since the dose deposited in the nose is largely below the minimal dose required by intranasal inoculation, this would indicate that the preferred site of infection initiation during aerosol inoculation is the lower respiratory tract. Another relevant observation is that whereas the clinical symptoms initiated by aerosol inoculation covered the spectrum of symptoms seen in natural infections, the disease observed in study participants infected experimentally by intranasal drops was milder, with a longer incubation time and usually no involvement of the lower respiratory tract (13,20). For safety reasons, this finding led to the adoption of intranasal drop inoculation as the standard procedure in human experimental infections with influenza virus (13).
Additional support for the view that the lower respiratory tract (which is most efficiently reached by the aerosol route) is the preferred site of infection is provided by studies on the use of zanamivir for prophylaxis. In experimental settings, intranasal zanamivir was protective against experimental inoculation with influenza virus in intranasal drops (21). However, in studies on prophylaxis of natural infection, intranasally applied zanamivir was not protective (22), but inhaled zanamivir was significantly protective (22,23). These experiments and observations strongly support the view that many, possibly most, natural influenza infections occur by the aerosol route and that the lower respiratory tract may be the preferred site of initiation of the infection.
Epidemiologic Observations
In natural infections, the postulated modes of transmission have included aerosols, large droplets, and direct contact with secretions or fomites because the virus can remain infectious on nonporous dry surfaces for <48 hours (24). Because in practice completely ruling out contributions of a given mode of transmission is often difficult, the relative contribution of each mode is usually difficult to establish by epidemiologic studies alone. However, a certain number of observations are consistent with and strongly suggestive of an important role for aerosol transmission in natural infections, for example the “explosive nature and simultaneous onset [of disease] in many persons” (9), including in nosocomial outbreaks (25). The often-cited outbreak described by Moser et al. on an airplane with a defective ventilation system is best accounted for by aerosol transmission (26). Even more compelling were the observations made at the Livermore Veterans Administration Hospital during the 1957–58 pandemic. The study group consisted of 209 tuberculous patients confined during their hospitalization to a building with ceiling-mounted UV lights; 396 tuberculous patients hospitalized in other buildings that lacked these lights constituted the control group. Although the study group participants remained confined to the building, they were attended to by the same personnel as the control group, and there were no restrictions on visits from the community. Thus, it was unavoidable at some point that attending personnel and visitors would introduce influenza virus in both groups. During the second wave of the pandemic, the control group and the personnel sustained a robust outbreak of respiratory illness, shown retrospectively by serology to be due to the pandemic strain influenza A (H2N2), whereas the group in the irradiated building remained symptom free. The seroconversion rate to influenza A (H2N2) was 19% in the control group, 18% in personnel, but only 2% in the study group (27,28).
Whereas UV irradiation is highly effective in inactivating viruses in small-particle aerosols, it is ineffective for surface decontamination because of poor surface penetrations. It is also ineffective for large droplets because the germicidal activity sharply decreases as the relative humidity increases (28). Furthermore, because the installation of UV lights was set up in such a way as to decontaminate the upper air of rooms only, large droplets would not have been exposed to UV, whereas aerosols, carried by thermal air mixing, would have been exposed (27,28). So in effect in this study only the aerosol route of infection was blocked, and this step alone achieved near complete protection.
The converse occurrence, blocking only the large droplet and fomites routes in natural infections, can be inferred from the studies on the use of zanamivir for prophylaxis described previously. In experimental settings, intranasally applied zanamivir was protective against an experimental challenge with influenza by intranasal drops (21). However, in studies on prophylaxis of natural disease, intranasal zanamivir was not protective (22), which leads to the conclusion that natural infection can occur efficiently by a route other than large droplets or fomites. As noted above, inhaled zanamivir was significantly protective (22,23).
Discussion and Implications for Infection Control during Influenza A (H5) Pandemic
In principle, influenza viruses can be transmitted by 3 routes: aerosols, large droplets, and direct contact with secretions (or with fomites). These 3 routes are not mutually exclusive and, as noted above, may be difficult to disentangle in natural infections.
For the purpose of deciding on the use of N95 respirators in a pandemic, showing that aerosol transmission occurs at appreciable rates is sufficient. Evidence supporting aerosol transmission, reviewed above, appears compelling. Despite the evidence cited in support of aerosol transmission, many guidelines or review articles nevertheless routinely state that “large droplets transmission is thought to be the main mode of influenza transmission” (or similar statements) without providing supporting evidence from either previously published studies or empirical findings. Despite extensive searches, I have not found a study that proves the notion that large-droplets transmission is predominant and that aerosol transmission is negligible (or nonexistent). Reports on many outbreaks suggest that influenza aerosols are rapidly diluted because long-range infections occur most spectacularly in situations of crowding and poor ventilation (25,26). However, even if long-range infections do not readily occur when sufficient ventilation exists, this does not rule out the presence at closer range of infectious particles in the micron or submicron range, against which surgical masks would offer little protection (29,30). Many infection control practitioners have argued that the introduction of large-droplets precautions in institutions has proven sufficient to interrupt influenza outbreaks and therefore that aerosol transmission appears negligible. This evidence is, unfortunately, inconclusive because of several confounding or mitigating factors. First, unless precise laboratory diagnosis is obtained, respiratory syncytial virus outbreaks can be mistaken for influenza outbreaks (9), which would artificially increase the perceived “effectiveness” of large-droplets precautions against influenza. Second, serologic studies are often not conducted, and therefore asymptomatic infections are not documented (among healthcare workers a large fraction of influenza infections are asymptomatic or mistaken for another disease [31]). Third, since we are in an interpandemic period and the viruses currently circulating have been drifting from related strains for decades, we all have partial immunity against these viruses, immunity that is further boosted in vaccinated healthcare workers. It has even been argued that after several decades of circulation the current human influenza viruses are undergoing gradual attenuation (32). Finally, surgical masks (used in large-droplets precautions) do not offer reliable protection against aerosols, but they nevertheless have a partially protective effect, which further confuses the issue (29,30).
In contrast, the situation with a pandemic strain of influenza A (H5) would become only too clear because no one would have any degree of immunity against such a virus, vaccines would not be available for months, and these viruses would likely be highly virulent. Even though efficient human-to-human transmission of the A (H5N1) virus has not yet been observed (by any mode), transmission of influenza A (H5N1) from geese to quails has been demonstrated in the laboratory (33). Thus, even in the current incarnation of A (H5N1), infection by the virus can generate aerosols that are infectious for highly susceptible hosts. As far as we know, 1 of the main blocks to efficient human-to-human transmission of influenza A (H5N1) is the virus’s current preference for specific sialic acid receptors. The current strains still prefer α-2,3–linked sialic acids, which is typical of avian influenza viruses, whereas human influenza viruses bind preferentially to α-2,6–linked sialic acids (34–36). In all likelihood, 1 of the mutations required for influenza A (H5N1) to give rise to a pandemic strain would be to change its receptor affinity to favor the α-2,6–linked sialic acids. For the influenza A (H1N1) pandemic strain of 1918, this change required only 1 or 2 amino acid substitutions (36). Once a highly transmissible strain of influenza A (H5) has arisen, it will likely spread in part by aerosols, like other human influenza viruses.
Recent studies have shown that whereas epithelial cells in the human respiratory tract express predominantly the α-2,6 sialic acid receptor, cells expressing the α-2,3 receptor were detected only occasionally in the upper respiratory tract; however, measurable expression of α-2,3–linked sialic acid receptors was found in some cells in the alveolar epithelium and at the junction of alveolus and terminal bronchiole (35). Binding of influenza A (H5N1) virus can be demonstrated in human tissue sections from the respiratory tract in a distribution corresponding to that of the α-2,3 receptors in the respiratory tract (34,35). This pattern of virus binding correlates well with autopsy findings, which show extensive alveolar damage (34,37), and also correlates well with the observation that recovery of the A (H5N1) virus is much more difficult from nasal swabs than from throat swabs (37). Thus, in the respiratory system the current strains of A (H5N1) appear to infect mostly (perhaps exclusively) the lower respiratory tract. If that is indeed the case, it in turn suggests that human cases of avian influenza were acquired by exposure to an aerosol, since large droplets would not have delivered the virus to the lower respiratory tract. (Another hypothesis might be gastrointestinal infection, followed by viremia and dissemination, but not all patients have gastrointestinal symptoms [37]). Given the strong evidence for aerosol transmission of influenza viruses in general, and the high lethality of the current strains of avian influenza A (H5N1) (37), recommending the use of N95 respirators, not surgical masks, as part of the protective equipment seems rational.
Several infection control guidelines for influenza have recently been published, some specifically aimed at the current strains of A (H5N1), others as part of more comprehensive pandemic plans that address the emergence not only of a pandemic form of A (H5) but also of other types of pandemic influenza viruses. Even though to date human-to-human transmission of A (H5N1) remains very inefficient, the high lethality of the infection and potential for mutations call for prudence. The use of N95 respirators is included in the 2004 recommendations of the Centers for Disease Control and Prevention for healthcare workers who treat patients with known or suspected avian influenza (38). The World Health Organization’s current (April 2006) guidelines for avian influenza recommend the use of airborne precautions when possible, including the use of N95 respirators when entering patients’ rooms (39).
Currently, several pandemic plans differ considerably in their recommendations for infection control precautions and PPE. The current version of the Canadian pandemic plan recommends surgical masks only, disregarding data that support the aerosol transmission of influenza (4). The US pandemic plan (5), as well as the British plans from both the National Health Service (available from http://www.dh.gov.uk/PublicationsAndStatistics/Publications/PublicationsPolicyAndGuidance/ PublicationsPolicyAndGuidanceArticle/fs/en?CONTENT_ID=4121735&chk=Z6kjQY) and the Health Protection Agency (http://www.hpa.org.uk/infections/topics_az/influenza/pandemic/pdfs/HPAPandemicplan.pdf), acknowledges the contribution of aerosols in influenza but curiously recommends surgical masks for routine care; the use of N95 respirators is reserved for protection during “aerosolizing procedures” (5,40). These recommendations fail to recognize that infectious aerosols will also be generated by coughing and sneezing. The Australian Management Plan for Pandemic Influenza (June 2005) recommends N95 respirators for healthcare workers (http://www.health.gov.au/internet/wcms/Publishing.nsf/Content/phd-pandemic-plan.htm), and in France, the Plan gouvernemental de prévention et de lutte <>(January 2006) recommends FFP2 respirators (equivalent to N95 respirators) (http://www.splf.org/s/IMG/pdf/plan-grip-janvier06.pdf).Given the scientific evidence that supports the occurrence of aerosol transmission of influenza, carefully reexamining current recommendations for PPE equipment would appear necessary.
Treanor JJ. Influenza virus. In: Mandell GL, Bennett JE, Dolin R, editors. Mandell, Douglas and Bennett’s principles and practice of infectious diseases. 6th ed. New York: Elsevier Churchill Livingstone; 2005. p. 2060–85.
Knight V. Airborne transmission and pulmonary deposition of respiratory viruses. In: Hers JF, Winkles KC, editors. Airborne transmission and airborne infections. VIth International Symposium on Aerobiology. New York: Wiley; 1973. p. 175–82.
Douglas RG. Influenza in man. In: Kilbourne ED, editor. The influenza viruses and influenza. New York: Academic Press; 1975. p. 375–447.
Loosli C, Lemon H, Robertson O, Appel E. Experimental air-borne influenza infection. 1. Influence of humidity on survival of virus in air. Proc Soc Exp Biol Med. 1943;53:205–6.
Centers for Disease Control and Prevention. Interim recommendations for infection control in health care facilities caring for patients with known or suspected avian influenza. 2004 [cited 2006 Apr 12]. Available from http://www.cdc.gov/flu/avian/professional/pdf/infectcontrol.pdf
Tellier R. Review of aerosol transmission of influenza A virus. Emerg Infect Dis [serial on the Internet]. 2006 Nov [date cited]. Available from http://www.cdc.gov/ncidod/EID/vol12no11/06-0426.htm
A deadly epidemic feared to be pneumonic plague has broken out in eastern Democratic Republic of Congo (DRC), WHO said on Fri, 29 Sep 2006.
There are dozens of suspect cases and up to 20 deaths in the outbreak, which a WHO team is investigating along with health ministry officials, WHO plague expert Eric Bertherat said. “There is an epidemic which we are trying to confirm is the plague in the northeast Ituri region,” Bertherat told Reuters.
Preliminary indications point to pneumonic plague, the most deadly and least common form of the disease, which can be spread by humans without involvement of fleas, he said. “It seems it could be the pneumonic form, which is extremely contagious with a high mortality rate of about 50 percent … At least several dozen cases are reported and up to 20 fatalities,” Bertherat said.
The outbreak is around Isiro, north-east of the eastern city of Kisangani in the remote, mineral-rich Ituri region.
In early 2005, 150 cases of plague were confirmed in Zobia, north of Kisangani, half of them fatal, according to the WHO. Many of the miners working at the diamond mine in Zobia fled the outbreak and spread the highly contagious disease.
Rapid diagnosis and treatment with antibiotics is essential to reduce complications and fatality, according to the WHO.
[Primary pneumonic plague (1 percent of natural plague presentations) arises as a result of inhalation of plague bacilli in infectious aerosols, such as would be produced when there are secondary pneumonic complications in bubonic/septicemic plague.
Primary plague pneumonia has a short incubation period of 1-3 days, after which there is sudden onset of flu-like symptoms including fever, chills, headache, generalized body pains, weakness and chest discomfort. A cough develops with sputum production, which may be bloody, and increasing chest pain and difficulty in breathing. As the disease progresses, hypoxia (low oxygen concentration in the blood) and hemoptysis (coughing up blood) are prominent. The disease is invariably fatal unless antimicrobial therapy commences within 24 hours of exposure.
Patients with primary pneumonic plague generate large quantities of infectious aerosols that pose a significant risk to close contacts.
CDC guidelines identify contacts within 2 meters as being at greatest risk and do not consider the organism likely to be carried through air ducts or vents. Persons who have been in contact with pneumonic plague patients or handling potentially infectious body fluids or tissues without appropriate protection should receive preventive antimicrobial therapy. The preferred antimicrobial agents for prophylaxis are tetracyclines, quinolones, or chloramphenicol.
Two children have been sickened by _E. coli_ bacteria in a case associated with unpasteurized milk, the state Health Department said Thu, 28 Sep 2006.
The milk came from Grace Harbor Farms, a dairy operation in Whatcom County, the department said in a statement. Testing confirmed both cases were caused by the same strain of the bacteria, _E. coli_ O157:H7.
The Health Department release said both children drank milk from the dairy, whose products are available in several counties through health food stores, PCC Natural Markets and Whole Foods Market. The children were identified only as a King County boy and a Snohomish County girl. The boy remains hospitalized in Seattle.
“Consuming raw milk can be risky,” especially for children, the elderly and people with other health problems, said Janet Anderberg, a specialist with the agency’s Food Safety Program.
The state Department of Agriculture is investigating the dairy and its operations. “Grace Harbor is a licensed raw milk producer and has been very cooperative during this investigation,” said Jerry Buendel, an Agriculture Department assistant director for food safety and consumer services.
The milk in question is already off store shelves, the Health Department said, but it encouraged consumers to return or dispose of any Grace Harbor raw milk they may have.
The Health Department noted that recommendation does not involve Grace Harbor pasteurized milk products.
“We’re very concerned, very sorry it happened,” Tim Lukens, president and general manager of Grace Harbor Farms in Lynden, said in a telephone interview. He stressed that the problem involved raw milk, not the dairy’s pasteurized milk. While he said he has not yet seen “an absolute test on our milk that shows it is the same _E. coli_,” he said he totally agreed with the recall.
An _E. coli_ O157:H7 outbreak late in 2005 also was linked to raw milk, which prompted the Legislature to toughen regulation of the industry.
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