As the three-month-old outbreak of swine flu raises havoc during the winter season in the Southern Hemisphere, officials in the United States are carefully seeking clues from there to deal with its likely return in this country in the fall, before a vaccine can protect large numbers of people.
Although much about the swine flu pandemic and the virus remains unknown, experts say this outbreak has exposed several weaknesses in the world’s ability to respond to the sudden emergence of a widespread illness.
Over all, the pandemic’s severity has been “moderate” compared with past influenza pandemics, the World Health Organization says, although it has spread with “unprecedented speed” to at least 168 countries. And although influenza typically strikes in colder months, the swine flu virus, A(H1N1), has swept through summer camps in the United States and Canada. That pattern has led to the prevailing belief that many more people will get swine flu than seasonal influenza this fall and winter, but that the country could face outbreaks of both strains, perhaps at different times.
One of the weaknesses that officials and experts point to is that despite years of planning it is evident that the infrastructure of the health departments in many countries, including the United States, is inadequate (in varying degrees) to deal with the sudden appearance of a new strain of influenza. Also, the number of beds in hospital intensive-care units and emergency rooms is limited, as is equipment like mechanical respirators to help patients breathe when the virus attacks the lungs.
Another problem is communication.
Officials and experts say they have learned a lot about human swine influenza. But relatively little of that information, including periodic summaries of what has been learned since the beginning of the pandemic, has been reported and published. Some experts said researchers were waiting to publish in journals, which can take months or longer. Journals impose severe penalties for disclosing information before publication, although they say they exempt matters of public health importance. Whatever the reason, delays in reporting such information can hamper plans for public health responses.
Few experts can match the personal overview that Dr. Richard P. Wenzel, chairman of the department of internal medicine at Virginia Commonwealth University in Richmond, has had of the swine flu virus’s activity in the United States, Mexico and four South American countries. At the invitation of former trainees in those countries and aided by some travel support from industry, he has visited them to observe cases, advise on control measures and critique their data.
Dr. Wenzel, a former president of the International Society for Infectious Diseases, said he had observed a broad spectrum of illness from human swine influenza: people who experienced few or no symptoms to those who rapidly developed complications and died.
The standard definition of influenza includes a fever. But an odd feature of the new virus is the lack of fever in a significant proportion of documented cases, even after some patients become seriously ill. In Chile, it was about half, in Mexico City about a third and elsewhere, less, Dr. Wenzel said. Lack of fever has been noted by other observers in several Canadian cases.
Analysis of data from specimens yet to be tested may shed light on how often infected individuals who have no fever spread the virus.
Epidemiologists stress the need for rigorous methodology to produce the solid data that is crucial for planning. For example, a need exists to account for the several-week delay that can occur between the onset of symptoms and death in influenza and other illnesses. Failure to take that time lag into account can seriously underestimate the death rate, depending on when in the course of the pandemic the information is obtained.
So absence of fever among substantial proportions of patients, when fever is specified in the definition, can cause serious underestimation of case totals.
Also, absence of fever limits the usefulness of thermal scans to identify people who have the virus and thus control the pandemic.
Diarrhea is a symptom that appears to be occurring in a larger percentage of cases than in seasonal influenza, giving clear reason to reinforce the importance of frequent hand washing.
Dr. Wenzel said he had urged his doctor hosts to test patients’ stools to determine how often the virus is present and the extent to which it is responsible for transmission.
Few such studies have been done, and there are reports that laboratories have received samples inadequate for testing.
Little specific information is available about when infected people stop shedding the virus, and thus stop spreading the illness. That information is particularly needed for those with impaired immune systems from H.I.V. infection, chemotherapy and anti-rejection drugs used in organ transplants.
Mexican doctors found the swine influenza virus on the hands of workers, on tables next to patients’ beds, on other hard surfaces and on a computer mouse, Dr. Wenzel said. So, he added, “infection control in hospitals must be assiduous to prevent spread, particularly those with impaired immune systems.”
The course of illness can become life-threatening in just a few hours among patients who had shown only mild symptoms, Dr. Wenzel said, but his visits showed that “doctors know little about what treatment works in severe cases.”
Two more unusual features of the new virus are that pregnancy, particularly in the third trimester, and obesity seem to increase the risk for complications of the infection.
Dr. Anthony E. Fiore, an influenza epidemiologist at the Centers for Disease Control and Prevention in Atlanta, said that “we were unable to find” published articles that looked at obesity as a risk factor.
Studies are under way, he said, to clarify whether obesity is an independent risk factor for complications of influenza or whether obese people have conditions like heart disease, asthma and other chronic lung ailments that put them at such risk.
Dr. William Schaffner, chairman of preventive medicine at Vanderbilt University in Nashville, said many people were reluctant to acknowledge that they or family members are obese. The 10 centers in a C.D.C.-sponsored program to track influenza hospitalizations, he said, have started collecting information on height, weight and body index to better determine obesity’s predisposition to complications.
Doctors actively involved in patient care are hampered by the lack of a standard, reliable rapid test to determine if a patient has swine influenza or some other respiratory illness. The diagnosis of swine influenza A(H1N1) has to be made through special tests known as P.C.R., for polymerase chain reaction. The tests are used in research laboratories but otherwise are generally available only through local and state health departments.
The P.C.R. tests, even if offered by a commercial laboratory, generally cannot be done in time to help a doctor determine whether a patient in an office, a clinic or a hospital has seasonal or swine influenza — a factor in determining what treatment to offer.
That situation has imposed new demands for local and state health departments that are working under severe budget restraints. Health departments doing the tests may be able to tell medical practitioners about swine influenza activity in geographical regions, but not in individual cases.
“We are stuck diagnostically,” Dr. Schaffner said. He added, “While we have increased expectations of what public health departments can do, and the science behind it, we do not have the infrastructure to do it.”
For example, last spring, Dr. Schaffner’s team at Vanderbilt conducted drills to retest their pandemic plans and learned that while some things worked very well, others had problems.
The area assigned for setting up an expanded outpatient clinic no longer existed because a new building had been constructed. “So we had to quickly find a new place,” Dr. Schaffner said. In addition, some elements of the pandemic plan had not been completed because the staff had been busy with other things.
The drills also showed the need to better plan for replacing absent hospital administrators “who are critical in determining which phase of your pandemic plan you are going to move into.”
Dr. Schaffner is trying to alert other institutions to the kinds of gaps identified by Vanderbilt, which has strived to be well prepared.
Health professionals and the public, Dr. Schaffner said, should be receiving more information in a timelier way about what has been learned about the swine influenza pandemic. Some such information is often reported at scientific meetings, but the summer is the doldrums for such gatherings.
Speaking about some of the gaps in clinical and epidemiological details, Dr. Schaffner said that “it is worth being tough and saying how come we do not know more.”
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