Northwestern University Feinberg School of Medicine

Program in Public Health

Behind the Public Face of Healthcare - A Look Inside the Illinois Department of Public Health

In the face of growing efforts to reduce states’ financial commitments and streamline responsibilities, various government agencies are increasingly under pressure to justify their existence. In this article, I assess the success of a state agency, the Illinois Department of Public Health, in maintaining and promoting public health across the state—and in making that work known.

Public Health in the Public Eye

Doctors and nurses tend to be the face of public health in America, and why not? When we get sick or need a vaccination, we head to our nearest health clinic and are seen by a healthcare professional who treats us and sends us on our way.

We are often less aware of the vast network and infrastructure of public health agencies that exist outside of this clinical setting. This lack of visibility makes it difficult for these agencies to procure funding for their work. The function of public health work is to keep the population healthy before problems arise, but since the press tends not to cover the absence of an outbreak, public health agencies for the most part stay out of the limelight.

The Illinois Department of Public Health (IDPH) serves as a centralized agency for public health-based screening and testing in Illinois. It houses laboratories in Springfield, Carbondale, and Chicago that provide essential health-related services that are not often visible to the general population. A few of these services are reviewed here.

We are often less aware of the vast network and infrastructure of public health agencies that exist outside of this clinical setting.

Newborn Screening

Every day in Illinois between 500 and 700 infants are born. From 24 to 48 hours after birth, each of these infants undergoes a “heel stick.” This procedure consists of a nurse pricking the infant’s heel with a needle and collecting seven blood spots on filter paper. These filter paper spots are dried and packed into an envelope at the end of the day and sent off to the IDPH for processing. This is where health work leaves the public eye. The next time the patient has contact with these samples is when the doctor calls and tells the parents that everything is fine and their baby is healthy, or that follow-up tests are needed. What happens in the interim?

Every day around 11:00am, the filter paper samples reach the newborn screening laboratory, which is by far the largest section at the Chicago branch of the IDPH. These samples are sorted in the mail room and passed onto employees who run the screening tests.

Each screening test performed at IDPH uses as its sample the filter paper blood spots from the heel stick. On a Monday, when the samples have built up over the weekend, there could be as many as 2,100 blood samples run per diagnostic test. In Illinois, all infants are screened for biotinidase deficiency, galactosemia, congenital adrenal hyperplasia, hypothyroidism, phenylketonuria, sickle cell disease, amino acid/urea cycle disorders, fatty acid oxidation disorders, organic acid disorders, and cystic fibrosis. Results from these tests are returned to the clinician, where they reappear in the public eye in the form of a note on a patient’s record or a phone call from a doctor.

Table 1: Newborn Screening Tests

Disease Basis of Disease Prevalence
Galactosemia Absence of GALT, an enzyme that breaks down galactose


Biotinidase Deficiency Absence of functional biotinidase, inability to extract biotin from food source


Hypothyroidism Absence of functional thyroid hormone 1:3,500
Sickle Cell Disease Hemoglobin disorder Variable
Congenital Adrenal Hyperplasia Absence of the hormone cortisol 1:15,000

Amino Acid Disorders, Urea Cycle Disorders,

Organic Acid Disorders, Fatty Acid Oxidation Disorders

Elevated analyte levels Variable
Phenylketonuria (PKU) Elevated phenylketone levels 1:12,000
Cystic Fibrosis Pulmonary and pancreatic insufficiency 1:4,000

Water Testing

The IDPH also has a significant behind-the-scenes role in the health of swimmers and beachgoers in the state of Illinois. On hot summer days, thousands of Illinois residents head down to the beach for a swim only to find that it’s been closed due to high E. coli counts. Those closures are based on tests performed by the IDPH. Bacteria and contaminants in the water are dredged up by swimmers or by runoff during a strong rain, and then they multiply in the lake water. Once every two weeks, the IDPH receives water samples from public beaches collected by local county health department sanitarians and tests them for E. coli contamination.

A colilert™ packet, which contains a substrate that turns yellow when metabolized by coliforms and fluoresces when metabolized by E. coli, is added to each water sample. The next day, the sample is analyzed by eye and under fluorescent lights to measure coliform and E. coli contamination. If the E. coli count is over 235 CFU/100mL, the beach is closed until the count is low enough to safely permit swimming.

coliform 300 by 225 e coli wate 300 by 225
Figure 1: Water samples under normal light, where the water has turned yellow from the colilert™ substrate that has been metabolized by coliforms present in the lake water. Figure 2: Water sample under UV light, where the water is fluorescing from the colilert™ substrate that has been metabolized by E. coli present in the lake water.

Dairy Testing

We often read about foodborne illness outbreaks, but less well known are the measures taken to prevent them. The environmental microbiology section of the IDPH receives samples from the local county health sanitarians who bring in cream, milk, ice cream, and raw mixes from dairy companies across Illinois. These dairy samples are diluted and spotted on petrifilm™ paper, which allows the coliform units to be counted. When these counts are over a certain threshold, the dairy company is notified not to release those products to the public.

Bacterial contamination is not the only concern with dairy products; antibiotic levels also need to be tested. When a cow has mastitis, an infection of the udder, it’s given antibiotics, and these β-lactams are then present in the milk it produces. This is a problem on two levels: it contributes to the overutilization of antibiotics, and it could also pose a serious hazard for those who are allergic. To test for β-lactam levels, a sample of the dairy product is placed on media that has been inoculated with bacteria and a growth enhancer. If antibiotics are present in the dairy product, a lack of bacterial growth will be seen.

dairy samples 283 by 325 dairy coliforms 283 by 325
Figure 3: Dairy mixes that are collected by county sanitarians from dairy companies and delivered to the IDPH for testing. Figure 4: Coliforms (red dots) present in the dairy sample that have grown on the petrifilm™.

Sexually Transmitted Infections (STIs)

The IDPH also provides STI testing. Every day in the afternoon, swab, urine, and blood samples from patients seen at public clinics come in by mail or by messenger to be tested for chlamydia, gonorrhea, HIV, and syphilis. Between 200 and 400 samples are collected in the mail room of the IDPH and are processed for testing daily. Polymerase chain reaction (PCR), in which bacteria are lysed and DNA is amplified, is run on urine and swab samples, testing for the presence of gonorrhea and chlamydia. Venous blood samples are tested for the presence of antibody against HIV antigen and Treponema pallidum, the bacterium that causes syphilis. This testing is incredibly thorough; two separate assays are used to test for the presence of HIV antibody in venous blood samples, and PCR is used as a final gold standard if the results are inconclusive or contradictory. Three separate assays are also utilized for syphilis testing, all of which rely on antigen-antibody binding. 

The results are faxed back to public health clinics, which then alert the patient whether or not he or she needs to come back for treatment. In the case of a positive test, a health officer will often also notify all the reported sexual partners of the patient to alert them of the need to get tested and treated as well.

This role of the IDPH in monitoring STIs in the state is especially important considering the fact that as of 2011 Cook County had the highest rate of gonorrhea1 and second highest rate of chlamydia2 of anywhere in the US.  


Every winter a new flu vaccine is issued to the public, and the IDPH plays a part in its production. During the flu season, clinicians send nasopharyngeal swabs to the IDPH from patients who are exhibiting influenza symptoms. Using PCR, the IDPH classifies the category of influenza virus that is the etiologic agent of the flu, and then sends these samples onto the CDC. Scientists at the CDC use these influenza samples from all over the United States to predict what the prevalent influenza virus subtype will be for next winter, and from there they create the subsequent year’s vaccine. 


From time to time, residents of Illinois come into contact with animals suspected of having rabies. When this happens, Animal Care and Control (ACC) euthanizes the animal and, if it’s a large species, severs the head. Once the animal has been taken care of, the resident needs to know if they should go to their healthcare provider for a rabies vaccination. 

The IDPH performs this testing. Every afternoon, severed heads from animals suspected of having rabies are delivered to the IDPH. There, they are dissected, and the cerebellum and medulla are extracted. The brain tissue is probed with fluorescent labels that bind to any viral particles that would be present in an infected animal. In the case of a positive assessment, ACC and the Springfield lab are notified. These organizations then contact affected residents to let them know that they should be vaccinated immediately.   

Lead Testing

Most residents of Illinois receive an informational packet about lead poisoning when they move into a new apartment or home. Some of the older buildings in Chicago and the suburbs still have lead-based paint; if this paint sheds from the walls and is unknowingly ingested or inhaled, it could lead to lead poisoning.

When patients go to their doctors for suspected lead poisoning, a blood sample is drawn and the venous blood is tested for lead levels, but what about the environmental exposure?

Any soil, paint or miscellaneous object that is suspected of being a source of lead poisoning is sent to the IDPH. There, the sample is ground, dissolved in acid, and run through an inductively coupled plasma optical emission spectrometer. This instrument provides a reading of the lead levels present in the sample. If the sample returns a reading over the acceptable threshold, the IDPH and the local county health department work in tandem to remediate the lead content or area.

This is not a test tube. This is a person.

After two months at the IDPH one thing is clear—public health workers in agencies like the IDPH provide invaluable services and they count on our support to keep their doors open. While the IDPH is hidden from public view and few are aware of its existence, the staff at the IDPH are keenly aware of their work’s significant implications to the quality of life of everyday citizens. As the departments of the IDPH test the never-ending stream of dairy, water, blood, urine, sputum, and swab samples that arrive every day, the source of that sample and the impact of the result is always on their minds. The most impressive aspect of this organization is the care it takes of its “patients” even when these patients are completely unaware of its existence. The employees of the IDPH take pride in their work, and if asked why, they will hold up a sample and state, “This is not a test tube. This is a person.”



About the Author


Celeste Mallama is a third-year PhD/MPH candidate in the Driskill Graduate Program at Northwestern University. She works in the laboratory of Dr. Nicholas Cianciotto, examining the interaction between Legionella pneumophila and the host innate immune system. She spent the summer of 2013 at the Illinois Department of Public Health, completing her field experience for her MPH.