As this year’s deer season winds down, it might help to remember that we, too, are being hunted. A legion of viruses, bacteria and protozoa are out there looking to bag a suitable human host. Part of the Minnesota Department of Health’s charge is to monitor what critters make up that legion from year to year, and the MDH has released its surveillance data from 2007. The annual summary (PDF) is 27 pages long, but I’ve condensed it into an alphabetically ordered, family-friendly tome that might make Cliff Clavin weep with delight.
Anaplasmosis (and other tick-borne illnesses)
It was a banner year for Minnesota’s three tick-borne illnesses, all of which were at record levels: Lyme disease increased by 36 percent (1,239 cases), Human Anaplasmosis by 83 percent (322 cases), and Babesiosis by 22 percent (24 cases). All three are brought to us courtesy of the blood-sucking deer/blacklegged tick, and not by the bulkier wood tick, which in this part of the country doesn’t carry any contagion.
For the second year in a row, Crow Wing County was our state’s Lyme disease champion, reporting 21 percent of case exposures. While 45 percent of cases involved metro residents, the vast majority of those folks contracted the illness while “up nort’.” Having said that, if you’re a metro resident looking to get Lyme disease without all the travel hassles, the northern portions of Anoka and Washington counties are your best bet. And set up a deer feeder in the backyard — the deer will bring the ticks to you.
Practically speaking we’re talking about the West Nile Virus (WNV). Since its arrival in July of 2002, there have been 441 cases of WNV and 14 deaths here in Minnesota (though the true number of infections is hard to measure: most of those infected with WNV will have only mild symptoms — headache, malaise, fever — and not seek medical attention).
Since West Nile Virus is spread between birds (the incubator) and humans via mosquitoes, you may not be surprised to hear that a warm spring and early summer in 2007 pushed WNV cases up to the highest level since 2003. But you may be surprised to know that the majority of WNV cases didn’t come from what we typically think of as Minnesota’s mosquito hellhole: the Boundary Waters/Arrowhead region. The mosquito that feeds heavily on birds, Culex tarsalis, is rare or absent in those areas; but it is plentiful in Western and Central Minnesota, and that’s where 75 percent of cases were reported.
Campylobacter (and other varieties of food poisoning)
Here’s an ugly group, in order of activity here in Minnesota: Campylobacter, salmonella, shigella, and E.Coli 0157: H7. If you’ve had one of these, you won’t forget it.
While most Minnesotans picked up their case of Campylobacter stateside, it’s a common cause of “Montezuma’s revenge,” and about a quarter of the cases in 2007 contracted it while traveling. Because antibiotics are cheap and easily available in Montezumaland, an increasing number (64 percent) of Campylobacter organisms acquired south of the border are resistant to quinolones, the antibiotic most commonly prescribed for the infection.
Salmonella has nothing to do with salmon, really, but it does show up when food is contaminated by the infected offal of animals like chicken or beef cattle. MDH reports outbreaks from the following sources in 2007: peanut butter, chickens (live), puffed-rice-and-corn snack, pet turtles, a Chinese buffet restaurant in Hennepin County, dry pet food, a Mexican restaurant in Hennepin County, frozen pot pies, tomatoes at a sandwich restaurant in Olmsted County, an office potluck, and a grocery store deli in Wadena County.
E. Coli 0157’s ability to create certain toxins makes it formidable and potentially lethal. The MDH provides lots of data on E. Coli, but one outbreak report makes the critical, if often overlooked point: Diarrhea is infectious! After a July potluck held at a high school in Hennepin County, 17 people came down with E. Coli. The most likely source of contamination? A 5-year-old child with diarrhea prior to and during the potluck dinner who had self-served fruit and chips. “Prior” and “during.” Keep this in mind this holiday season: Stick to the stuff that requires a serving utensil. And if you’re the cook, remember that the most under-recognized protective step is to cook ground meat through-and-through. Whole meat cuts are not much of a problem, because if they’re contaminated it’s only on the surface, where the heat of cooking easily fries the contaminant.
Although shigella can be transmitted via food, it’s typically transmitted person-to-person. That’s why it commonly shows up in children and day-care centers. Fortunately, the number of shigella infections in Minnesota went down in 2007.
One could put a protozoa called cryptosporidium in with the above diarrhea crowd, because the intestines are the primary site of infection and it can be transmitted via food or person-to-person contact. But Cryptosporidium’s ability to tolerate chlorine levels that easily kill other bacterium like E.Coli give it a swimming-pool niche. Of the five outbreaks in 2007, two were associated with membership club swimming pools, and one with a hotel water park. Again, if your child has a diarrheal illness, keep him out of the pool, and out of the potluck line.
HIV infection and AIDS
The good news is that HIV has become a very treatable illness, and the bad news is that the good news eliminated a certain fear factor, as in the fear of death. The number of new HIV cases reported in 2007 rose to 229, a 24 percent increase from 2003. Although 90 percent of new cases occurred in the metro area, cases have been found in 80 percent of counties statewide.
The demographics of who gets HIV are changing. Since the beginning of the HIV epidemic, white males practicing male-to-male sex have been the predominant mode of transmission. Although white males still make up the largest group of the newly infected here in Minnesota, the number of Hispanic and African-born males becoming infected with HIV are rising sharply. Also, more women are being infected with HIV. In 1990 they made up just 10 percent of new HIV cases, but they made up 23 percent of the total in 2007; 90 percent of these new cases came from sex with an infected male partner.
In 2007, there were approximately 6,000 Minnesotans living with HIV/AIDS.
Compared to the year before, the 2007-2008 flu season saw a larger spike in the number of outbreaks in long-term care facilities, but fewer school-related outbreaks. As it did the year before, the peak for influenza activity came in late February/early March, which is why it’s never too late to get vaccinated. Having said that, only 22 percent of the influenza strains isolated in the public health labs were well matched to the three strains in the 2007-2008 vaccine. There’s a lot of hard science that goes into deciding what strains should be included in the next year’s vaccine, but there remains a bit of viral roulette.
This bacteria was named after it was discovered to be the causative agent of an outbreak of severe pneumonia at an American Legion convention in 1976. You don’t have to have served in the Armed Forces to get it, but Legionella does prefer to infect smokers and those with emphysema (and since the military handed out cigarettes with K-rations in World War II, a collection of vets in ’76 may have been fertile field for an outbreak). Legionella loves water, and contaminated drinking supplies are the main vector. There were 31 cases in Minnesota in 2007, not bad for a state with 10,000 lakes.
There were just six cases of listeriosis in 2007, but they all ended up in the hospital, and two died. Elderly folks, pregnant women, those with weakened immune systems, and newborns are at the highest risk. To avoid infection, one should avoid soft cheeses (no, Velveeta is not a cheese), unpasteurized milk, poorly reheated meats (particularly deli meats and whatever’s in hot dogs), and unwashed raw vegetables.
A 16-month-old child was the only case of measles in 2007. The child had been vaccinated against measles at 1 year of age, but developed the rash two days after returning from an extended visit to Japan. Fortunately there were no secondary cases.
There are several bacteria that can infect the lining of the brain and spinal cord — the meninges — but Neisseria meningitidis is the most common amongst adults. The infection can be debilitating or even lethal, and it seems to carry a predilection for teens and young adults (outbreaks in freshman dormitories being a classic case). In 2007 there were 22 cases, with a median age of 19. Fortunately, a vaccine against the organism became available in 2005, so we can hope this bacteria will fade from view.
Staph aureus is the most common cause of wound infections. In the early days of antibiotics, all it took was a whiff of penicillin to knock down an infection with Staph aureus, but over time the bacteria developed a resistance to penicillin, a kind of biochemical deflector shield. So scientists tweaked the penicillin molecule enough to restore its lethality and they renamed it methicillin. The tweak worked for a while, but bacteria aren’t stupid, and eventually methicillin-resistant Staph aureus (MRSA) showed up. Fear not, we still have a few antibiotics that can kill MRSA, but most of them come only in intravenous form (rather than a pill), and they can be trickier to use.
Traditionally, MRSA showed up in patients who had either been in a nursing home, hospital, or dialysis unit, but the numbers show that MRSA is becoming an equal-opportunity infector. MDH reports that in 2007, 50 percent of all patients with an MRSA infection had picked it up in the community rather than from within the health care system. The number was only 12 percent in the year 2000. Again, MRSA doesn’t have any magical infective powers — but its resistance to common antibiotics means that an MRSA infection can get a head start if we keep our big guns — the antibiotics capable of killing MRSA — in reserve. And yet if we use our MRSA-killing antibiotics as first-line therapy, we will only be inviting more drug resistance.
One of the “M”s in the MMR vaccine for children stands for mumps. There were 28 cases of mumps in 2007, down from a resurgent 2006, when 180 cases were reported. Vaccine recommendations for mumps have assumed that those born before 1957 had natural immunity: They had been exposed to the virus itself. But it appears that immunity wanes over time — four of the cases involved people who were born before 1957.
Speaking of waning immunity, how about pertussis, the “p” in DTP/DTaP vaccine, and better known as “whooping cough”? Unvaccinated children are at the highest risk of infection, but waning immunity means persons of any age can get it, and even an immunized child is not completely immune. In 2005, over 1,500 Minnesotans found themselves with violent coughing spasms (only a third of sufferers do the namesake “whoop”), but fortunately in 2007 that number was down to 393.
Sexually transmitted diseases
Chlamydia topped the Minnesota STD charts in 2007, with over 13,000 cases. As STDs go, Chlamydia often produces only mild symptoms, but it can cause severe pelvic infections in women which can lead to infertility by scarring the fallopian tubes shut. The venerable gonorrhea was the second most common STD, with about 3,500 cases. The increase in the number of STDs outpaced interest returns on most money market funds, with 4- and 5-percent increases in Chlamydia and gonorrhea respectively. Adolescents and young adults are the highest risk of infection (surprise!), and the highest rates of infection occurred in communities of color.
In case you hadn’t heard, syphilis is still around. Though the total numbers are not large (58 cases in 2007), they’ve remained elevated since a 2002 outbreak involving men who have sex with men.
This the major bacterial player in community acquired pneumonia, and it’s also important in middle-ear infections in children. The release of a vaccine against some of the most common strains of strep pneumoniae in 2000 has put a real dent in the number of streptococcal infections. But the data also shows that other strains, those not covered by the vaccine, are stepping into the power vacuum. One strain’s curse is another strain’s blessing.
Group A strep
This is the bacteria behind the “flesh-eating strep” lore. There were 173 cases statewide, and 16 people died. As the numbers suggest, this is an uncommon but deadly serious infection: Once Group A strep gets into deep tissues or the bloodstream, the results can be calamitous. However, the bug seems to need some upper hand to be lethal: All the deaths were in people with significant underlying medical problems.
It’s still good advice: Wear your shoes outside — and stay current on your tetanus shot. A 10-year-old boy spent two-and-a-half weeks on a ventilator in the ICU, and a month in the hospital, after he contracted tetanus from a deep laceration of the foot. He got it while running around a farm without shoes.
Toxic Shock Syndrome (TSS)
Certain strains of Staph aureus bacteria are capable of producing toxins that are quite, well, toxic. The infection first came to light in the early 1980s in association with highly absorbent tampons, and although the number of menstrual-associated TSS cases have declined with the withdrawal of those products, tampon use remains a risk. The higher the absorbency, the longer the continuous use in a cycle, and the longer a single tampon is in place, the higher the risk. Fortunately, there were only nine cases of TSS in 2007.
Tuberculosis is a very slow-growing bacteria that enters the body through the lungs (hence the tuberculous cough), but it can also spread to other parts of the body. There were 238 cases of TB in Minnesota in 2007, up 10 percent from the year before. Eighty-five percent of cases involved someone who was foreign-born, typically in sub-Saharan Africa (66 percent) or South/Southeast Asia (18 percent). TB in the foreign-born typically involved someone between the ages of 15 and 44 who has been here for more than two years. More than half of these foreign-born cases involved TB in organs other than the lungs, which is not the case nationally.
The data suggests that many of these foreign-born cases contracted their TB before their arrival in the United States. This is not a vote of confidence in the pre-immigration medical screenings done overseas. MDH suggests that at least half of the foreign-born cases of TB here in Minnesota could be prevented by tighter screening measures.
You think that “flesh-eating strep” is scary? To my mind, drug-resistant TB is a whole lot more onerous. Each year, 2 percent of TB cases in Minnesota are found to be multidrug resistant (MDR). A third of the MDR cases cultured in the last five years were resistant to all four of our first-line TB drugs. Now that is scary.
Since 1995 the MN Department of Heath has had a surveillance system to track unexplained critical illnesses and deaths of possible infectious etiology. Likely this system would have been able to identify something like HIV/AIDS much earlier than we did (the book “And the Band Played On” chronicled the goggle-eyed response to the epidemic). MDH investigated 64 unexplained deaths in 2007 and found no common theme.
If you had chicken pox as a kid, you’ve already had the varicella-zoster virus. While it is a relatively benign illness in children, it can be more serious in adults, and in any person with serious underlying medical problems or who is on immune-suppressing drugs. There is now a vaccine for the virus (though there have been supply problems) and children need to be vaccinated prior to kindergarten and again in seventh grade. The vaccine is now being recommended for those older than 60, because varicella-zoster can lie around dormant in the body and return in one’s senior years as the dreaded “shingles,” a painful burning rash. In a worst-case scenario, the rash goes away but the pain doesn’t.
Vaccine or no, in 2007 there were outbreaks in 40 schools and 22 counties statewide, involving 487 students.
Viral Hepatitis A
This virus infects the liver and is passed in the stool. Therefore it prefers contaminated foods and poor sanitation. A number of the ninety-four cases in 2007 were picked up while traveling — most commonly to Mexico, or Central or South America — but you needn’t go that far: There were outbreaks in restaurants in Hennepin and Murray counties. Hepatitis A is rarely fatal, and doesn’t lead to scarring of the liver — cirrhosis — the way Hepatitis B or C can. Fortunately, B and C are transmitted with much more difficulty and almost always involve serious “cultural exchanges”: sex and needles.
Dr. Craig Bowron is a Twin Cities internist and writer who reports on medical topics for MinnPost. He can be reached at cbowron [at] minnpost [dot] com.