Monitoring Infections: Active vs. Passive Surveillance (2023)

By Cindi Crosby, PhD

For the past 20 years I have attended many conferences, both national and international, on the topic of healthcare-associated infections (HAIs). The fundamental debate still continues, however, as to the actual frequency of HAIs. Most infectious disease physicians, infection preventionists and epidemiologists agree that HAIs are under-reported. Why? Could it be in the way we conduct our surveillance?

Today, most HAI surveillance is passive, relying on data retrospectively gathered from medical records. Conversely, active surveillance involves prospective steps to identify patients who have or who may develop HAIs, using standardized definitions of infection, pre-determined criteria, and protocols that result in risk-adjusted HAI incidence rates.

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Implementing and maintaining an active surveillance system requires personnel and financial resources, and so its often crucial to justify the investment with improved patient outcomes. Outcomes may then be used to develop targeted intervention programs. At a high level:
Active surveillance may be most directly associated with monitoring and controlling the risk of outbreaks of drug-resistant pathogens, such as methicillin-resistant Staphylococcus aureus (MRSA).
Increasingly, active surveillance has been used to identify patients at high risk for infections associated with surgery and hospitalization in intensive care units (ICUs).Â

Here are several more detailed examples of published outcomes from active surveillance programs:

(Video) Public Health Surveillance

Active surveillance to decrease MRSA isolates
Healthcare institutions are acutely aware of the rise in drug-resistant pathogens. In 1980, MRSA accounted for about 2 percent of all S. aureus HAIs. By 2006, it accounted for more than 60 percent.1 In response, some hospitals initiated active surveillance testing of patients considered high-risk for active MRSA infections or colonization. One hospital system using passive and ICU-targeted surveillance recorded no change in MRSA isolates over a three-year period. They implemented an active surveillance program to universally screen all patients upon admission for nasal colonization with MRSA.2 Patients found to be colonized received treatment with mupirocin nasal ointment and periodic bathing with antisepsis soap. For each year after initiation of active universal screening, the hospital recorded decreases in MRSA and total S. aureus clinical isolates compared to each of the prior three years of passive surveillance (P < 0.0001). The author of this study suggests that the decrease in MRSA isolates correlates with decreased disease.

Active surveillance to decrease surgical site infections
Active surveillance may be particularly useful in identifying surgical site infections (SSIs), which can develop up to 30 days after a patient is discharged. In one study of SSI rates identified passively by neurosurgeons,surgeons missed 36 percent of SSIs using passive surveillance, as evidenced by results from active surveillance performed by infection control professionals.3 Under-reporting HAIs with passive surveillance has been shown to be more likely among certain types of surgical patients during the post-discharge period. In a Dutch study of post-discharge SSI rates for various surgeries, more SSIs were identified with a recommended active surveillance protocol (43 percent) than with passive surveillance (25 percent).4Â This study also demonstrated that for common surgeries including appendectomy, knee prosthesis surgery, mastectomy and hysterectomy, most SSIs developed after discharge and were underestimated when passive surveillance was used.

Active surveillance of device-associated infections
Patients at risk for device-associated infections such as catheter-associated urinary tract infections (CAUTIs) and ventilator-associated pneumonia (VAP) may benefit from active surveillance designed to identify risk factors that are unique to a particular patient population or hospital unit. An active surveillance program undertaken at Alexandria University Hospital in Egypt included an objective to identify etiologic and antibiotic resistance patterns associated with CAUTIs in the facilitys four ICUs.5 During a 13-month study period, 757 patients in the ICU who had existing urinary catheters or who were catheterized after ICU admission were monitored. The overall infection rate was 15.7 CAUTIs per 1,000 catheter days, with the following risk factors identified:
Female gender
Previous catheterization within the same hospital admission
Admission to the chest unit
Patient age 40 or older
Prolonged duration of catheterization
Prolonged hospital and ICU stay

(Video) Surveillance | PSM lecture | Community Medicine lecture | PSM made easy | PSM rapid revision | Arpit

In addition, the pathogen profile was identified, including Candida (51 percent), Gram-negative pathogens (33.5 percent), and Gram-positive organisms (15.4 percent). The prevalence of extended-spectrum beta-lactamase-producing organisms included E. coli (78.6 percent) and K. pneumoniae (56 percent). Investigators concluded that existing infection control policies were inadequate, and a tailored intervention to address these specific risk factors and microorganisms is now being designed.
Active surveillance was also used to guide evidence-based VAP prevention strategies in one tertiary medical-surgical trauma ICU in Saudi Arabia.6 VAP cases were diagnosed according to predefined criteria, and VAP microbiology, risk factors, and outcomes were recorded. The intervention program resulted in a decrease in VAP infection from 19.1 to 6.3 per 1,000 ventilator days from 2003 to 2009. Active surveillance identified the following risk factors for VAP:
Accidental extubation
Trauma versus medical diagnosis
Chronic obstructive pulmonary disease
Neuromuscular blockade

The most common isolated pathogens were Gram-negative organisms. Investigators realized a reduction in VAP rates with active surveillance, reporting, and evidence-based preventive strategies and identified modifiable risk factors to be included in additional interventions.
Of note, another active surveillance testing program designed to identify MRSA colonization and institute contact isolation of affected patients in two Michigan hospitals also resulted in a decrease in VAP in both hospitals, although MRSA infection decreased in only one hospital.7 The investigators concluded that active surveillance testing with contact precautions was effective in reducing both VAP and MRSA in their facilities.

Economic consequences of surveillance
These studies are just a few examples of successful active surveillance programs that resulted in reduced infection rates. But even if active surveillance is shown to improve patient outcomes, are we prepared to actively capture HAI data? I would speculate that many institutions are not. A common objection to implementing active surveillance is the cost of labor and economic resources, particularly during a time when healthcare institutions are under pressure to reduce the cost of care. Those providers who are not taking steps to lower the risk and incidence of HAIs, however, may be taking an even greater financial risk. Extended lengths of stay, antibiotic days, and readmissions are costly and create longer-term economic pressure. In a study by Dimick et al. (2004), median total hospital costs for patients with and without post-operative infection alone were $13,083 vs. $ 5,044, a statistically significant result.8

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The difference between passive and active surveillance may seem like an academic debate among infection control professionals, but the consequences in terms of patient morbidity and costs of care are real and affect everyone.Â

Cindi Crosby, PhD, is vice president of global medical affairs for CareFusion. The author wishes to acknowledge Catherine M. Jarrell, MA, medical affairs consultant at CareFusion, for providing medical writing assistance.

1. Hall G, Flayhart D. Active surveillance culture as a promising new tool. Infection Control Today. Available at: Accessed on February 15, 2012.
2. Hacek DM, Paule SM, Thomson RB Jr, Robicsek A, Peterson LR. Implementation of a universal admission surveillance and decolonization program for methicillin-resistant staphylococcus aureus (MRSA) reduces the number of MRSA and total number of S. aureus isolates reported by the clinical laboratory. J Clin Microbiol. 2009;47:3749-52.
3. Heipel D, Ober JF, Edmond MB, Bearman GM. Surgical site infection surveillance for neurosurgical procedures: a comparison of passive surveillance by surgeons to active surveillance by infection control professionals. Am J Infect Control. 2007;35:200-2.
4. Manniën J, Wille JC, Snoeren RLMM, van den Hof S. Impact of postdischarge surveillance on surgical site infection rates for several surgical procedures: results from the Nosocomial Surveillance Network in The Netherlands. Infect Control Hosp Epidemiol. 2006:27:809-16.
5. Talaat M, Hafez S, Saied T, et al. Surveillance of catheter-associated urinary tract infection in 4 intensive care units at Alexandria university hospitals in Egypt. Am J Infect Control. 2010;38:222-8.
6. Al-Dorzi HM, El-Saed A, Rishu AH, et al. The results of a 6-year epidemiologic surveillance for ventilator-associated pneumonia at a tertiary care intensive care unit in Saudi Arabia. Am J Infect Control. 2012. [Epub ahead of print]
7. Martinez-Capolino C, Reyes K, Johnson L, et al. Impact of active surveillance on meticillin-resistant Staphylococcus aureus transmission and hospital resource utilisation. J Hosp Infect. 2010;74(3):232-7.Â
8. Dimick JB, Chen SL, Taheri PA, Henderson WG, Khuri SF, Campbell DA Jr. Hospital costs associated with surgical complications: a report from the private-sector National Surgical Quality Improvement Program. J Am Coll Surg. 2004;199:531-7.

(Video) Surveillance in epidemiology | types | active, passive and Sentinel | epidemiology



What is the difference between active vs passive surveillance? ›

An active surveillance system is one where health facilities are visited and health care providers and medical records are reviewed in order to identify a specific disease or condition. Passive surveillance systems are less time-consuming and less expensive to run but risk under-reporting of some diseases.

What is one advantage of active surveillance versus passive surveillance? ›

Active Surveillance Systems

It can also be used to collect data on rare diseases such as Reye syndrome or vCJD. The system has a number of advantages over passive surveillance, such as improved sensitivity and representativeness, as well as the collection of a more detailed dataset.

Does the CDC use active or passive surveillance? ›

The National Notifiable Diseases Surveillance System (NNDSS)[3] is a passive surveillance system that includes all the diseases and conditions under national surveillance. Efforts are being made to integrate and enhance surveillance systems for national notifiable diseases.

What are the two types of surveillance used in epidemiology? ›

EBS is one of two main types of surveillance used to identify and track infectious diseases and other public health events. These two types of public health surveillance – event-based surveillance and indicator-based surveillance – complement one another.

What are examples of active surveillance? ›

Active surveillance is a process whereby state or local agencies actually look for evidence of disease risk. For example, when trying to find if a certain virus carried by mosquitoes is in Texas, mosquitoes are collected and sent to the lab for testing.

What is an example of passive surveillance? ›

Surveillance can be either passive or active. With passive surveillance, reports are received from physicians, hospitals, laboratories, or other individuals or institutions.

What are the pros and cons of passive surveillance? ›

Passive Surveillance Advantages • Cost. Easier to design and carry out. Useful for monitoring trends over time. Disadvantages • Low sensitivity.

What is the disadvantage of active surveillance? ›

Active surveillance has one big advantage: Men whose prostate cancer doesn't grow can avoid surgery or radiotherapy, including the side effects. One disadvantage is that, if the cancer progresses, it may be discovered too late. It may have already spread to other parts of the body by then (metastasis).

Why is passive surveillance difficult to detect? ›

Passive surveillance relies on the detection of clinical signs and is thus not designed to detect subclinical disease. The reporting threshold to contact a veterinarian or authorities (or similar step by which the reporting chain is initiated) is a major limitation to passive surveillance.

What are the 3 main types of public health surveillance? ›

Passive surveillance, active surveillance, and also syndromic surveillance. Passive surveillance is the most common form of surveillance and occurs when laboratories, physicians, or other healthcare providers regularly report cases or disease to the local health department.

What are the three types of surveillance? ›

The three types of surveillance are direct, preconstructive, and reconstructive.

What are the different types of surveillance CDC? ›

CDC surveillance systems fall into four broad categories covering infectious diseases, noninfectious health conditions, both infectious and noninfectious diseases and health conditions, and risk factors and exposures.

What are the 4 types of surveillance? ›

Types of Surveillance in Criminal Investigations
  • Electronic Monitoring. Electronic monitoring, or wiretapping, refers to the surveillance of email, fax, Internet and telephone communications. ...
  • Fixed Surveillance. ...
  • Stationary Technical Surveillance. ...
  • Three-Person Surveillance. ...
  • Undercover Operations.

What is the difference between passive surveillance? ›

Passive surveillance is a concept based around wiretapping and other kinds of surveillance that constantly gather information, rather than actively pursuing targeted results. Passive surveillance versus active surveillance is part of a growing conversation about privacy and security in the digital world.

What are the different types of surveillance methods? ›

  • Computer.
  • Telephones.
  • Cameras.
  • Social network analysis.
  • Biometric.
  • Aerial.
  • Corporate.
  • Data mining and profiling.

What is passive vs active surveillance epidemiology? ›

Consequently, passive systems tend to under-report disease frequency. Active Surveillance occurs when a health department is proactive and contacts health care providers or laboratories requesting information about diseases.

What is active surveillance in infection control? ›

Conversely, active surveillance involves prospective steps to identify patients who have or who may develop HAIs, using standardized definitions of infection, pre-determined criteria, and protocols that result in risk-adjusted HAI incidence rates.

What is active surveillance methods? ›

Listen to pronunciation. (AK-tiv ser-VAY-lents) A treatment plan that involves closely watching a patient's condition but not giving any treatment unless there are changes in test results that show the condition is getting worse.

What is the difference between active and passive pharmacovigilance? ›

Unlike passive pharmacovigilance, which is based on largely voluntary (and hence incomplete) spontaneous reports of adverse drug reactions with limited information on patient characteristics, active pharmacovigilance is based on electronic health records containing detailed information about patient populations, ...

What is the difference between monitoring and surveillance? ›

Monitoring is a general term that refers to the systematic, continual, and active or passive observation of persons, places, things, or processes. By contrast surveillance is used to indicate targeted monitoring of activities by police or security officials for specific evidence of crimes or other wrongdoing.

What is the advantage of active surveillance? ›

Advantages. As you won't have treatment while you're on active surveillance, you'll avoid the side effects of treatment. Active surveillance won't affect your everyday life as much as treatment might. If tests show that your cancer might be growing, there are treatments available that aim to cure your cancer.

Why is active surveillance good? ›

Why it's done. Active surveillance for prostate cancer is used to avoid treatment side effects when the risk of the prostate cancer progressing is very low. Because prostate cancer grows very slowly, some very small cancers may never cause signs and symptoms.

Why is passive surveillance important? ›

Passive surveillance contributes vital observations in support of national and international surveillance programs, detecting potentially unknown issues in the wider landscape, beyond points of entry and the plant trade.

What is the disadvantage of passive surveillance? ›

Both passive and active systems have advantages and disadvantages, which must be weighed when planning (Table 1). Passive systems can suffer from underreporting or compromised accuracy of reporting and show selection bias depending on the source of reports or laboratory specimens.

What are the characteristics of active surveillance? ›

Timeliness, to implement effective control measures; Representation, to provide an accurate picture of the temporal trend of the disease; Sensitivity, to allow identification of individual persons with disease to facilitate treatment; quarantine, or other appropriate control measures; and.

Which attacks are more difficult to detect passive or active attacks? ›

Passive attacks are very difficult to detect because they do not involve any alteration of the data. When the messages are exchanged neither the sender nor the receiver is aware that a third party may capture the messages.

What is the sensitivity of passive surveillance? ›

Analysis of passive surveillance data

The sensitivity of disease detection at the cluster (herd) level is 0.018. The sensitivity of disease detection at the population level is 0.16.

What are three limitations of disease surveillance? ›

Limitations of Notifiable Disease Surveillance and Recommendations for Improvement. Surveillance need not be perfect to be useful. However, surveillance might have limitations, particularly as a result of underreporting, lack of representativeness, and lack of timeliness, that compromise its usefulness.

What are the different types of health surveillance? ›

As defined in certain regulations, you must use medical surveillance where there could be exposure to certain high hazard substances or agents.
Medical surveillance
  • asbestos.
  • lead.
  • ionising radiation.
  • compressed air.
  • COSHH.
Nov 8, 2021

What are the two types of surveillance criminal investigation? ›

Physical surveillance is one of the oldest law enforcement investigative tools.

What is passive surveillance in pharmacovigilance? ›

Passive surveillance methods involve the usage of spontaneous adverse event reports voluntarily sent by healthcare professionals or patients to the marketing authorization holder or regulatory authority. Here, data related to the adverse reactions are collected in a central or regional database.

What is the most common form of surveillance? ›

Different surveillance methods

Here are some examples. Electronic surveillance – Electronic surveillance equipment is often the most used tool during an investigation. It could range from cameras and wiretaps to GPS tracking and more.

What are the difference between active and passive? ›

Active vs.

In a sentence written in the active voice, the subject of sentence performs the action. In a sentence written in the passive voice, the subject receives the action.

What is the difference between active and passive methods? ›

With active learning, students learn by getting involved in the information and synthesizing it through such methods as debate, experiments and other hands-on exercises. Passive learning is a more internal process in which students take in and memorize the information that is provided to them.

What is the difference between being active and passive? ›

In an active voice, the subject of the sentence performs the action. In passive voice, the subject is being acted upon by the verb.

What is the difference between active and passive examples? ›

Active voice: Jerry knocked over the lamp. Passive voice: The lamp was knocked over by Jerry. Both sentences describe the same action taking place—Jerry making contact with a lamp and causing it to fall over—with the first sentence making Jerry the subject and the second making the lamp the subject.

What are the three basic rules of active and passive? ›

Active And Passive Voice Rules For Conversion of Sentence
  • Rita wrote a letter. ( Subject + Verb + Object)
  • A letter was written by Rita. (Object) + (auxiliary verb) + (past participle) + (by subject).
  • She cooks food. ( Subject + Verb + Object)
  • The food is cooked by her. (
Aug 17, 2020

Why use active or passive? ›

In writing, always consider whether you should use the passive or active voice. It will depend on what you, the writer, want to convey: if you want to draw attention to the doer, use the passive voice; if your intent is to put the focus on the action, then you should go for the active voice.

Why is active vs passive important? ›

Using active voice often improves clarity, while passive voice can help avoid unnecessary repetition. Active voice can help ensure clarity by making it clear to the reader who is taking action in the sentence.

What is the main difference between active and passive components? ›

The most significant difference between active components and passive components is that an active component can supply power to an electric circuit, whereas a passive component cannot deliver power, it can only absorb the power in the circuit.

Why is active management better than passive? ›

“Active” Advantages

Among the benefits they see: Flexibility – because active managers, unlike passive ones, are not required to hold specific stocks or bonds. Hedging – the ability to use short sales, put options, and other strategies to insure against losses.

What is active and passive examples with answers? ›

Active Voice- I am eating dinner. Passive Voice- The dinner is being eaten by me. Active Voice- I was doing my assignment. Passive Voice- The assignment was being done by me.


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