Disease Control Bulletin: July 1999


disease control bulletin

Volume 1, Issue 3, 1999


A nationwide outbreak of 101 cases of listeriosis was identiied between August 1998 and February 1999. Two of these cases were from Vermont. The source of the outbreak was eventually identified as specific production lots of hot dogs and deli meats. The voluntary recall of the implicated lots on December 22, 1998 has been followed by several other recalls of meat (one was 30 million pounds) that were identified as being contaminated with Listeria monocytogenes. It is possible that some of these products are still stashed in the back of Vermonters’ freezers waiting to be pulled out for a backyard barbecue this summer.

(See the patient information).


Listeriosis is an uncommon but potentially fatal illness. The organism has a predilection for the central nervous system and placental tissue. Therefore, the disease most often presents as meningitis or overwhelming infection of a fetus leading to spontaneous abortion, stillbirth or neonatal death. Healthy adults and children occasionally become infected with Listeria but rarely become seriously ill. Symptoms may be limited to fever, fatigue, nausea, vomiting and diarrhea and may be easily dismissed. Persons at both ends of the age spectrum, newborns, the elderly and those who are immunocompromised or have underlying systemic disease are at greatest risk for manifestations of the more significant sequelae of this infection.


The causative organism, the bacterium Listeria monocytogenes is ubiquitous. It is found in soil and water and in everything that soil and water can contaminate. Animals fed on improperly fermented silage can become reservoirs for the organism, and without appearing ill can contaminate food for human consumption. Vegetables can become contaminated from soil or manure used as fertilizer. Milk can become contaminated from infected cows or soil in the environment. Raw milk and cheeses made from raw milk (i.e., unpastuerized dairy products) are often implicated in listeria outbreaks.

Listeria monocytogenes is a hardy organism.Abletosurvive under adverse conditions, it resists the effects of heating, drying and freezing. It can be killed by thorough cooking and by pasteurization, but apparently easily contaminates foods after processing unless good manufacturing practices are arduously followed. It is even able to grow at temperatures as low as 24° F, so it can multiply while under refrigeration. It also thrives on the refrigerator walls and can easily contaminate other foods.

Lately, this organism has been implicated in post-production contamination of luncheon/deli meats and hot dogs, that were intended to be eaten without further cooking.


The US Department of Agriculture Food Safety and Inspection Service (FSIS) is responsible for inspecting plants that slaughter or process meat, poultry, and egg products. The Food and Drug Administration (FDA) monitors cheese, dairy, sandwiches, prepared salads, and smoked fish. Both of these agencies have a “zero tolerance level” for Listeria monocytogenes in ready-to-eat products. On May 26, 1999, the FSIS published in the Federal Register a notice to manufacturers to advise them to reassess their preventive control plans to ensure they are adequately addressing the pathogen. On May 25, 1999, the USDA issued a news release recommending persons at risk for listeriosis take precautions with certain foods.

Control Measures

Because the organism does not change the taste or smell of food and can live on foods properly kept under refrigeration, it is more difficult to control than other food borne pathogens. Most people suffer no ill effect from this bacterium. However, those at greatest risk should use extra caution to prevent illness. Many of these people may be unaware of the risk of severe illness.

We ask that you consider sharing the enclosed information sheet with those persons. Control measures are targeted toward avoiding certain high-risk foods, i.e., deli meats and soft cheese, and general household hygiene. Health care providers should be aware of the symptoms of listeriosis and should caution pregnant women and other persons at greater risk for disease to avoid high-risk food to decrease risk of infection and potentially life-threatening disease.

CDC has been involved in a surveillance project for listeria infections since 1986. Based on information from this project, it is estimated that over 1800 cases occur in the US each year, perhaps resulting in 425 deaths. Listeriosis is a reportable disease inVermont.In1998,fourcaseswerereportedinVermont;todate in 1999, one case resulting in stillbirth has been reported. Early detection and reporting of cases helps identify sources of infection and prevent further cases of the disease.


Listeriosis Patient Information Sheet

Persons More Likely to Get Sick From Listeria Infection

Symptoms of Listeriosis

Recommendations for Those at Risk of Listeriosis

  1. Do not drink raw milk (unpasteurized milk) or food made from it.
  2. Reheat until steaming, hot dogs, cold cuts, pâté, luncheon or deli meats, fermented and dry sausage.
  3. Thoroughly cook raw foods from animal sources, such as beef, pork, and poultry. Use a reliable meat thermometer. Cook raw meat to an internal temperature of 160°F, raw poultry to 180°F,and raw fish to 160° F or until it is white and flaky.
  4. Avoid soft cheeses such as feta, Brie, Camembert, blue veined cheeses (e.g., Roquefort, Gorgonzola, Stilton), and Mexican-style soft white cheese (los quesos blandos, e.g., queso blanco, queso fresco, queso asadero, queso de hoja, queso de crema, cotija, ranchero, and queso enchiladol).
  5. Wash food preparation areas, cutting boards, and utensils with hot soapy water.
  6. The Listeria organism can survive in cold temperatures. Periodically, wash the inside of the refrigerator with hot soapy water also. Wipe up spills promptly.
  7. Separate cooked and uncooked foods to avoid cross contami-nation.Keeprawmeat,poultryandseafoodincontainerstoavoid contact with ready-to-be-eaten food . Store these items on lower shelves; do not store these items above foods that will not be cooked before eating to avoid drips onto food surfaces.
  8. Refrigerate or freeze perishable foods within two hours of purchase or preparation. Plan to use fresh meats and seafood within three days of purchase.
  9. Keep hot foods hot (above 140° F) and cold foods cold (below 40° F). Use a reliable refrigerator thermometer and check the temperature periodically to be certain the unit is functioning properly at 40° F or below.
  10. Divide leftover foods into shallow covered containers before refrigerating and reheat until steaming hot (170° F) before eating.
  11. Wash fruits and vegetables thoroughly before eating.
  12. Wash hands with soap and water before handling clean food items and after handling soiled items, in between handling cooked and uncooked foods, and after handling high risk food items such as ready-to-eat meats, raw meat, poultry, seafood and eggs.
  13. Heed media reports of recalled food products; observe expiration dates for perishable items that are precooked or ready-to-eat. Read and follow label instructions to “keep refrigerated” and “use by” a certain date.

NOTE: Although the risk for listerios is associated with foods from delicatessen counters is relatively low, pregnant women and immunocompromised persons may choose to avoid these foods or to thoroughly reheat cold cuts before eating.


Newborn Screening in Vermont

Statewide screening of newborns for certain inborn disorders had been in place—and successful—for many years before the formalization of Vermont’s newborn screening program in state regulation. Even without a state mandate, approximately 99 percent of Vermont newborns were tested for conditions which, if identified late, would result in permanent, serious or even life-threatening consequences. When identified immediately, these conditions can be treated and managed. Such diseases have included phenylketonuria (PKU), hypothyroidism, galactosemia, and homocystinuria.

Not all diseases of this nature are suitable for a newborn screening program, however. In selecting conditions for screening, states generally determine which conditions to include according to specific criteria. These criteria typically include the following—

The Vermont Newborn Screening Program — How It Works

Vermont newborns are tested for seven conditions: phenylketonuria (PKU), hypothyroidism, galactosemia, homocystinuria, Maple Syrup Urine Disease, Biotinidase Deficiency, and several hemoglobinopathies such as Sickle Cell Disease. Each of these screening tests are recommended by the Vermont Newborn Screening Advisory Committee after thorough study of the available tests and the degree to which they meet the public health goals and criteria listed above.Thiscommittee,made up of Vermont physicians and other specialists in the area of newborn screening and genetic disorders, meets annually to review current literature and technological advances. They also perform a semi-annual review of the program and its outcomes.

The program is managed bythe Department of Health and the Vermont Genetics Center of the University of Vermont. Vermont and other New England states send newborn screening specimens for testing to the Massachusetts State Laboratory Institute, now affiliated with the University of Massachusetts Medical School.

The role of the Health Department is one of assurance—assurance that the testing is performed, assurance that initiation

of treatment is timely, and assurance of quality. The department provides assistance to hospitals, health care providers, and parents in the implementation of the newborn screening program.

The current quality of the Vermont program depends greatly upon the collaboration and commitment of all partners in the system: the excellence of the hospital nursery parent information and specimen collection, the participation of midwives and home-delivery families, the accurate and timely reporting of results by the lab, and the thorough follow-up efforts of the Vermont Genetics Center and Vermont physicians. The Vermont effort is a model of what can be achieved by a consistent, statewide, collaborative approach.

New Advances in Technology

A significant technological advance in screening for metabolic disorders has been made with the development of Tandem Mass Spectrometry (TMS). TMS is an accurate testing method, which offers a much expanded “menu” of conditions that can be screened from a single specimen. This includes a large number of aminoacid, organic acid, and fatty acid oxidation disorders, many of which currently have no treatment.

As of February 1, 1999, the University of Massachusetts Medical School laboratory began using TMS testing, and Vermont’s tests are included. However, Vermont specimens are screened only for those conditions recommended by the Newborn Screening Advisory Committee. TMS is also performed by other newborn screening laboratories, including private, for-profit laboratories.

Future Directions and Issues

A major challenge for Vermont’s Newborn Screening Advisory Committee is to determine how to deal with the potential detection of metabolic disorders for which there are no interventions. TMS makes testing for many more conditions possible, but the availability of a test is only one of the many criteria needing consideration.

Vermont plans to continue its thorough, thoughtful course of action. The Newborn Screening Advisory Committee will meet regularly to review outcomes and quality measures. The committee will also re-examine the current conditions screened for and make recommendations to the Health Department regarding changes or additions as needed.

Ultimately, however, the goal is the same, the highest quality program based on the consistency, commitment and collaboration of all the partners in the newborn screening effort—hospitals, providers, and families.


Chronic Disease in Vermont: Arthritis

Trends in Arthritis Morbidity

Based on calculated national estimates, approximately 85,000 Vermonters(1) will be diagnosed with some form of arthritis bythe year 2000 and approximately 14,000 will have activity limitations related to arthritis. While Vermont ranks among the bottom ten states for self-reported arthritis estimates, the actual prevalence of arthritis in Vermont is unknown. Crude unweighted estimates from new arthritis-related questions on the (five months of data) 1999 Behavioral Risk Factor Surveillance Survey (BRFSS) show 23.5 percent of Vermonters in the sample report having a diagnosis of arthritis. Of those reporting arthritis, 32.9 percent reported osteoarthritis or degenerative arthritis, 14.1 percent reported rheumatoid arthritis, 4.4 percent reported rheumatism and 5 percent reported some other type. While these numbers cannot be interpreted as representative of Vermont’s population, it is interesting to note that they are higher than the national estimates for Vermont.

Hospitalization related to arthritis (2) shows a pattern very similar to the national figure of 2.4 percent in 1997: 2.7 percent of all hospital discharges in Vermont residents from 1993-1997 were related to arthritis. More men (45 percent of hospitalizations 1993-97) were hospitalized for arthritis in Vermont than nationally (39.3 %)(3). In 1997, arthritis hospital stays were shorter(3) in Vermont for those between age 15 and 44 (2.24 days) compared to the national average of 5.3 days for that age group. However, Vermont hospitalization patterns were very similar to the U.S. for all other age groups.

Knee replacements may serve as a surveillance definition for arthritis in the absence of arthritis prevalence data. In Vermont from 1988 to 1997, hospital discharges related to knee replacement (Figure 1) have increased an average of 10 percent per year for those age 65 and older, 9 percent per year for those age 45 to 64 and 26 percent per year for those age 15 to 44 (4). In 1997, the average charge for a total knee replacement in Vermont was $18,928.There were 534 kneereplacements in 1997 corresponding to $10.1 million in total hospital charges (4).

knee replacement surgery chart

Figure 1: Knee Replacement Surgery, 1988-1997 Discharges to Vermont Residents by Age

Risk Factors for Arthritis

Risk factors for osteoarthritis, the most common type of arthritis, include obesity, sports injuries and repetitive motion. In 1997, slightly more than one-third of all Vermonters (34.7%) were overweight (5): 44.3 percent of men and 25.3 percent of women. Another 15.9 percent of Vermonters were obese (5): 17.3 percent of men and 14.5 percent of women. The relative risk of osteoarthritis associated with obesity is in the range of two to four depending upon site of arthritis. The population-attributable risk suggests that up to 24 percent of knee arthritis could be attributed to obesity (6).

In 1996, approximately one-fifth of Vermonters (21.5%) reported no leisure time physical activity at all. The proportion of Vermont adults reporting regular exercise(7) was 23.8 percentwith a 95 percent confidence interval (95%CI) of [20.9,26.7] for men and 25.4 percent 95% CI [22.8,28.0] for women. These figures are slightly higher than the U.S. medians. Although young adults tend to be more active than older adults, the relationship between level of exercise and weight remains the same across all age groups. The proportion of Vermonters engaging in no leisure-time physical activity increases with the degree of overweight (Figure 2).

For more information about arthritis, including self-management courses, contact the Northern New England Chapter of the Arthritis Foundation at (802) 864-4988. The URL is <www.arthritis.org>.

percent of vermont adults who exercise based on weight category

Figure 2

and less than 30. Obesity is defined as body mass index (BMI) greater than or equal to 30. See Look-up table available at http://www.nhlbi.nih.gov/ nhlbi/cardio/obes/prof/guidelns/bmi_tbl.htm. BMI = multiply weight in pounds by 704.5; divide result by height in inches squared according to the NIH Clinical Guidelines on the Identification, Evaluation and Treatment of Overweight and Obesity in Adults: The Evidence Report, p. X. All data from the BRFSS are self-reported.

(6) Brownson, RC, Remington, PL, Davis, JR (eds.). Chronic Disease Epidemiology and Control. 2nd ed. Washington, D.C.: American Public Health Association, 1998, pg. 469, 470.

(7) Regular exercise was defined as at least five days per week for 30 minutes per session (self reported).


Selected Reportable Diseases Vermont,
Year to Date (07/03/99)

reportable diseases july 1999 vermont

No 5-year median available: Cryptosporidiosis; E. coli O15 7:H7; Group A Strep, Invasive, Hepatitis C


Rotavirus Vaccine Delayed Again

The National Immunization Program has announced that the Federal contract for rotavirus vaccine will not be available unti lthe first or second quarter of the year 2000. When the Federal contract is secured, the State Immunization Program will send out a notice of the effective date and the eligibility criteria for obtaining State supplied rotavirus vaccine. For those medical care providers who wish to purchase their own supplies of rotavirus vaccine, it is available from Wyeth-Lederle,(802)862-2849.


Call for Historical Articles

The January 2000 issue of the Disease Control Bulletin will focus on historical accounts of significant public health events in Vermont. This may include descriptions of disease outbreaks, special events, or milestones in public health. Anyone interested in contributing an article should contact Susan Schoenfeld at 863-7240 or 1-800-640-4374.



Between 6/15/99 and 7/2/99, four cases of culture-confirmed pertussis were reported to the Health Department.These individuals ranged from 7 to 15 years old. They resided in Chittenden (2) and Franklin (2) counties. Among the close contacts of these cases, at least nine individuals have clinically diagnosed pertussis, including two adults, six children and af our-month-old infant.

Vermont experienced an outbreak of pertussis lasting from July 1996 through April 1997. In 1996, 280 cases were confirmed, with 12 cases (4%) occurring in children less than one year of age. In 1998, 80 cases of pertussis were confirmed; eight cases (10%) were identified in children less than one year of age. In Vermont and throughout the United States, pertussis increasingly has been identified in adolescents and adults, who are often the unknowing source of infection for infants.

Protecting infants from pertussis is crucial, since they are most likely to experience serious consequences of infection. The eight infants with confirmed pertussis in 1998 were five months old or less. The four infants less than two months of age were hospitalized (one for 50 days). While these infants survived, the most severely ill child experienced pneumonia, seizures, and required ventilation and an extended intensive care stay. Seven of the eight infants were exposed to undiagnosed coughing illness among siblings or adults in the home. One family reported no contacts with coughing within the home. Exposure may have taken place when the infant was taken to a large outdoor event a week before symptom onset.

Pertussis in infants may exhibit classic symptoms such as cough lasting greater than two weeks, accompanied by paroxysmal coughing, whooping, or post-tussive vomiting. However, in young infants, whooping is often absent, and apnea may be the predominant symptom. Coughing may be atypical; gagging, cyanosis and seizures may be reported.

Pertussis is now recognized as an endemic disease with periodic peaks occurring every three to four years. Immunization confers a high degree of protection among children and infants who have received at least three doses of vaccine. However, fully immunized children of all ages may still develop pertussis; immunization protection wanes within 5-10 years of receiving the fifth dose. It is essential to consider pertussis in the differential diagnosis of people of all ages. It is particularly important to suspect pertussis in symptomatic persons who have contact with young infants. Infection can be prevented in the infant through prophylaxis. Early diagnosis, treatment, and supportive care for infants are important factors in improving outcomes.

Culture kits for pertussis testing can be obtained from the Vermont Department of Health by calling 1-800-660-9997 or 863-7560. Clinical or confirmed cases should be reported to the Epidemiology Field Unit at 1-800-640-4374 or 863-7240.