Minnesota Department of Health (MDH) Bug Bytes

March 28, 2011
Vol. 12: No. 1

Topics in This Issue:
1.  World TB Day
2.  Measles Outbreak
3.  Nuts, Hazel: E. coli O157:H7 Outbreak
4.  Influenza-related Deaths in Minnesota, 2010-11
5.  Pontiac Fever

1. World TB Day

World TB Day is observed every year on March 24. This date was chosen to honor Robert Koch, the German physician who discovered the tubercle bacillus and gave his famous lecture on “The Etiology of Tuberculosis” on March 24, 1882 in Berlin. Dr. Koch became known as the “father of bacteriology.” According to the Nobel Institute, “Koch's lecture, considered by many to be the most important in medical history, was so innovative, inspirational and thorough that it set the stage for the scientific procedures of the twentieth century. He described how he had invented a new staining method and demonstrated it for the audience. Koch brought his entire laboratory to the lecture room: microscopes, test tubes with cultures, glass slides with stained bacteria, dyes, reagents, glass jars with tissue samples, etc. …Koch showed tissue dissections from guinea pigs which were infected with tuberculous material from the lungs of infected apes, from the brains and lungs of humans who had died from blood-borne tuberculosis, from the cheesy masses in lungs of chronically infected patients, and from the abdominal cavities of cattle infected with TB. In all cases, the disease which had developed in the experimentally infected guinea pigs was the same, and the cultures of bacteria taken from the infected guinea pigs were identical. When Koch ended his lecture there was complete silence. No questions, no congratulations, no applause. The audience was stunned. Slowly people got up and started looking into the microscopes to see the TB bacteria with their own eyes.”  Twenty-three years later, Koch was awarded a Nobel Prize in Physiology or Medicine for his discoveries related to TB. He even has a crater on the moon named after him.

From 1700 to 1900, TB is estimated to be responsible for the deaths of approximately 1 billion people. At the time of Koch’s lecture in 1882, 7 million people (1/7 of all deaths) were dying of TB every year. Although TB is now largely under control in the United States and Europe, it continues to be one of the deadliest diseases worldwide. TB kills nearly 2 million people every year, including an average of 2 in Minnesota and over 500 in the United States. The number of TB cases nationally is at an all-time low, with 18 consecutive years of decline. Still, 11,545 TB cases were reported in the United States in 2009.

Following a decade of increasing numbers, TB incidence in Minnesota has now decreased for 3 consecutive years, with 135 cases being reported in 2010. Likely reasons for the decrease include a slowdown in the numbers of primary refugees coming to Minnesota from high-burden countries; enhanced pre-immigration testing and treatment overseas; and the everyday efforts of Minnesota health care providers, local health departments and others to detect and treat TB cases and their close contacts and to ensure proper infection control precautions.

While the decrease in TB in Minnesota is encouraging, we must remain vigilant. For every person with active TB, dozens more have latent TB infection. One tenth of them will develop active TB unless they receive preventive treatment. We can reach the goal of TB elimination by working together and strengthening partnerships. Our united effort is needed to reach those at highest risk for TB, and to identify and implement innovative strategies to improve testing and treatment among high-risk populations. In addition to ensuring that current TB control efforts are continued, new diagnostic tests and treatment regimens must be developed, and the capacity of health professionals to provide adequate treatment must be increased.

More information on World TB Day is at www.health.state.mn.us/divs/idepc/diseases/tb/worldtbday.html and www.cdc.gov/tb/events/WorldTBDay/default.htm

Learn more about: Tuberculosis>>


2. Measles Outbreak

We are in the midst of a measles outbreak. All cases are Hennepin County residents. Ten related cases of laboratory-confirmed measles have been identified in Minnesota to date. A serologic test for measles IgM antibody or polymerase chain reaction test on throat or urine specimens were positive for all cases. The ages range from 4 months to 4 years. Five are of Somali descent. Two congregate living facilities (3), one drop-in day care center (3), and an emergency room (2) are sources of exposure for 8 of the cases. Five of the cases were too young to be vaccinated and four were of age but unvaccinated; one vaccination status is unknown. Six of the cases were hospitalized. All are recovering. The first case had rash onset on February 26 and the most recent rash onset of the cases is March 23.

The index case has been identified as a 30-month-old American born child of Somali descent who traveled to Kenya prior to illness. The child was at a drop-in day care center 1 day prior to its rash onset and exposed 3 of the cases at this center, and another case within the household. A specimen from this child was genotyped at CDC as B3, a common variant in Kenya and other central African countries. There is currently a measles outbreak in Kenya.

An 11th unrelated measles case was confirmed in a 34 year-old with rash onset March 21 who was exposed during a trip to Orlando, Florida on March 1-10. Vaccination status is unknown.

Minnesota state and local health department staff are following up on persons who may have been exposed in specific clinical and community settings and providing immune globulin to susceptible persons. Multiple vaccination clinics have been held or scheduled at community venues with excellent work being done by the Hennepin County Health Department, Hennepin County Medical Center, and Children’s Hospitals and Clinics.

Learn more about: Measles>>


3. Nuts, Hazel: E. coli O157:H7 Outbreak

In February, we, along with Wisconsin and Michigan Departments of Health, investigated a cluster of 7 E. coli O157:H7 infections (3 in Minnesota residents) with indistinguishable PFGE patterns. Cases were predominately older males (median age, 62 years) and interviews revealed that all 7 reported consuming in-shell hazelnuts in the week prior to illness onset. Four reported purchasing the hazelnuts as part of mixed nuts and six purchased them from bulk bins at grocery stores. Product traceback investigations conducted by the Minnesota Department of Agriculture in conjunction with departments of agriculture in California, Michigan, and Wisconsin demonstrated that in-shell hazelnuts consumed by the 7 cases traced to a common distributor in California. In-shell hazelnuts collected from a Minnesota case’s household tested positive for E. coli O157:H7 with the outbreak PFGE pattern. This investigation led to the recall of hazelnut and mixed nut products from this distributor.

This was the first E. coli O157:H7 outbreak ever associated with in-shell nuts although outbreaks of salmonellosis associated with raw in-shell almonds occurred in 2004 and 2007. Hazelnuts grow on trees and are harvested by shaking them to the ground where they are swept up by a machine. While on the orchard ground, the nuts can come into contact with animal feces. The bacteria can then grow on the nuts. The contamination then can be spread to the nut meat when the nut is cracked or contaminate the nut eater’s hands.

This investigation like so many others started with the disease report submitted by you the clinician and infection control preventionist, and the isolate submitted by you the microbiologist. So, thank you all.

4. Influenza-related Deaths in Minnesota, 2010-11

As of March 28, 26 influenza-related deaths have been reported in Minnesota for the 2010-2011 influenza season.  The majority of cases (19/26, 73%) have been in those 65 years of age and older with 15/19 (79%) occurring in those 80 years of age or older.  Deaths in the elderly have all been related to influenza A (H3) or influenza A (type unknown).  Most deaths in those less than 65 years of age are related to influenza B or influenza A (2009 H1N1). One case occurred in a child who was co-infected with influenza B and MRSA and had a necrotizing pneumonia.

In contrast, during the 2009-2010 season when the A (2009 H1N1) pandemic strain dominated, the majority of deaths were in those 18-64 years of age (46/67, 67%).  During the 2009 H1N1 pandemic there were 8 pediatric deaths identified.  Two pediatric deaths have been identified to date for the 2010-2011 season.

Learn more about: E. coli O157:H7>>


5. Pontiac Fever

We recently investigated a Pontiac fever outbreak associated with a handball/racquetball club. On March 9, we received a complaint of approximately 30 individuals becoming ill with “flu-like” symptoms approximately 36 hours after attending a handball tournament March 4 and 5. Preliminary investigation revealed that several of the players had used a hot tub whirlpool in the men’s locker room. Based on the presence of the whirlpool and the symptoms of the individuals, Pontiac fever was suspected as the cause of the illnesses.

Of 73 individuals interviewed, 48 (66%) reported experiencing fever and/or chills within 48 hours of being at the club. Additional symptoms reported included fatigue (98%), headache (94%), muscle aches (94%), cough (62%), dizziness (44%), tightness in chest (43%), sore throat (26%), diarrhea (15%), and vomiting (2%). Nine (19%) cases visited a medical provider for their symptoms; 1 case was hospitalized overnight.

Being in the men’s locker room the evening of March 4 was associated with illness (43 of 48 cases vs. 0 of 23 controls; odds ratio, undefined; p < 0.001). The 5 cases who were not in the men’s locker room on March 4 had later onsets of illness than the rest of the cases, perhaps indicating a later exposure or a smaller dose.

A visit to the facility confirmed that there was an unlicensed whirlpool in operation in the men’s locker room. The whirlpool had been losing 3-6 inches of water a day for unknown reasons and was being filled with water from a hose attached to a sink in the locker room mechanical room. There was no history of the whirlpool ever having been chlorinated or otherwise disinfected. The whirlpool was drained and is no longer in use. Ventilation problems may have allowed aerosols to have spread outside of the men’s locker room.

Pontiac fever, a self-limited febrile illness, is caused by inhaling mists from a water source that contains Legionella bacteria. Pontiac fever differs from Legionnaires’ disease in that patients do not develop pneumonia. In general, persons with Pontiac fever recover in 2-5 days without treatment. It is named after an outbreak that occurred in 1968 at a health department building in Pontiac, Michigan that was re-investigated after the discovery of the etiological agent for Legionnaires’ disease in 1977.

Learn more about: Emerging Infections>>


Bug Bytes is a combined effort of the Infectious Disease Epidemiology, Prevention and Control Division and the Public Health Laboratory Division of MDH. We provide Bug Bytes as a way to say THANK YOU to the infection control professionals, laboratorians, local public health professionals, and health care providers who assist us.

For concerns or questions regarding content, please use our Bug Bytes Feedback Form.

You can also subscribe to the MDH Bug Bytes newsletter.

Updated Wednesday, December 21, 2011 at 08:58AM