Number of cases down, but virus could return
The influenza outbreak that unnerved Missoula during the second week of December has dwindled away. But the flu season is far from over, and Missoula could certainly experience another wave of the illness, health specialists said Tuesday.
A return of the same strain of influenza A would meet resistance because so many people have now been vaccinated or have had the illness, which develops immunity to it, said Pam Goldberg, a registered nurse who's a disease intervention specialist at the Missoula City-County Health Department. But a new strain introduced could cause the same sort of spike in the case numbers.
Last year, the strongest influenza outbreak came in late March, Goldberg said.
Outbreaks typically last four to six weeks, said Missoula physician and infectious disease specialist George Risi.
"The natural history of influenza outbreaks are for them to burn out sooner than you would think," he said.
But the reasons for Missoula's early season opener, in October, and when and where the next outbreak will be is all speculation, he said.
"We are, in some ways, waiting for the other shoe to drop," he said.
The first flu-related call came to the Health Department on Oct. 25. By Nov. 1, the department had marked 55 positive tests. The highest number of positive tests in Missoula was in the week of Nov. 15, when the city had 104.
Christmas week, there were 14 tested cases, and last week five or six, Goldberg said.
Tests are not an indicator of the number of cases in a region because not every case is tested. The number of tests doctors order tends to decline as the number of cases escalates because the presence of influenza is known in the community, and the symptoms are recognizable.
Flu was linked to the death of a Missoula toddler Dec. 8, but hasn't been blamed directly for other deaths since. However, many people, especially those who are older, die from conditions and illness aggravated by influenza.
Since the second week of December, the Health Department has corralled ample supplies of flu vaccine from the state and from a hospital that had extra, Goldberg said. All the children on the waiting list generated through a flu hot line that week were vaccinated.
"It was easily 200," she said. "We were able to do a good job for the kids."
Missoula's Health Emergency Advisory Team prioritized vaccine doses according to people's medical conditions. Now there is enough vaccine that anyone with any condition warranting a shot should visit the Health Department, Goldberg said, or call the flu hot line at 258-3500. Flu shots are given 9 a.m. to 11:30 a.m. and 1 p.m. to 4:30 p.m on weekdays.
At Community Medical Center, large numbers of outpatient flu cases have come and gone, said Gordon Opel, director of community services. The first positive test for influenza at Community's lab was during the week of Oct. 25. Positive tests peaked in mid-November. Last week there were two, he said.
During the month of November, Community had double the number of positive flu tests than it had had during any month in the previous two years, Opel said.
The hospital inpatient census is now about normal.
"It was a relatively short duration," Opel said. "It was very severe and intense, it was very short and it dropped very quickly."
At St. Patrick Hospital, the trend is similar. Its lab had 37 positive influenza A tests in November and 23 in December, said Chad Spangler, the hospital's infection control coordinator. The numbers of cases leveled off until mid-December, then declined sharply, he said, except for some emergency department admissions on Christmas Day.
The difference around the hospital is apparent, he said, in the few numbers of masks being worn by hospital staff as a precaution against infection from patients with flu-like respiratory symptoms.
Goldberg has recently been tracking RSV, a virus typical for this time of year. In healthy children, Respiratory Syncytial Virus looks like a bad cold. Last week, the Health Department learned of 11 cases. The week before brought nine.
Respiratory etiquette is the best defense.
"The best you can do is wash your hands," Goldberg said.
Reporter Ginny Merriam can be reached at 523-5251 or at firstname.lastname@example.org