Infection control

Tate Lowrey
Oct. 31, 2011, 4:17 p.m.

There are many things health facilities and crowded places need to do to reduce the spread of TB. This is called infection control.

TB is caused by a bacterium called Mycobacterium tuberculosis (M. tuberculosis). When individuals are infected with TB in their lungs, they can release tiny particles containing M. tuberculosis into the air by coughing or sneezing. Inhaling these particles can lead to an individual being infected with TB, especially in places with little or no ventilation or in susceptible populations (e.g. children, immune-suppressed individuals like those with HIV). The goal of TB infection control is to reduce the risk of respiratory droplets from coming into contact with those who are not infected.

TB infection control interventions focus on settings where there is a high risk of TB being spread such as health-care facilities (i.e. nosocomial infection), congregate settings (e.g. correctional facilities, homeless shelters), and households.

Administrative control measures are the core set of practices that should at the very least be implemented in any setting despite the availability of resources (see the Box). These activities prevent droplets containing M. tuberculosis from being in the air in the first place thereby reducing the exposure of staff and patients to TB.

Why is TB infection control important?

In 2010 alone, 8.8 million people became newly infected with TB around the world.ⁱ What is more, drug resistant forms of TB (ie. multidrug-resistant TB [MDR-TB] and extensively drug-resistant TB [XDR-TB]) are emerging and being spread as well.

TB is becoming increasingly associated with HIV. TB is the most common life-threatening opportunistic disease and leading cause of death in those living with HIV/AIDS.ⁱⁱ In many parts of the world, TB is fueling an already devastating HIV epidemic. TB is estimated to be between 20-37 times greater in people living with HIV than among those without HIV.ⁱⁱⁱ

Infection control measures enforced nationally and implemented locally are important to halt the spread of TB and it's detrimental effects on individuals and societies. Millions of people worldwide are needlessly infected and suffer the detrimental health consequences. TB infection control is a critical part in the global fight to end that suffering.

TB Infection Control Interventions

TB infection control interventions are an important component of any global or national TB prevention and control programme.. There are many guideline documents found around the world for TB infection control; some are national strategic plans, others are from international agencies such as the WHO and CDC.

Common to them is the recognition of the three main TB infection control measures (administrative, environmental and personal protective equipment) and their hierarchy of priority for implementation.

Health-Care Facilities

Because the incidence of TB in health-care facilities far exceeds that of the general population, millions of health-care workers are put at risk for TB everyday. For this reason, TB control measures are more rigorous and are a matter of urgency in health-care facilities.

Health-Care Facility Infection Control Measures

Administrative control measures 1st Priority

The most important control measures to be implemented in any setting. Highlighted here are some of the most critical interventions for minimizing exposure to TB.

Early and rapid diagnosis of TB:ensure all clinical staff are aware of signs and symptoms and diagnosis rapidly.

Screen, Educate, Separate: screen all patients entering facility, educate them on cough hygiene and separate/isolate patients so that others are not exposed to the infectious particles they generate.

Minimize time spent in health-care facilities: as little time possible should be spent with health-care workers (HCW), especially in hospitals and overcrowded or poorly ventilated areas. Community-based approaches for management of TB patients should be prioritized to keep patients out of hospitals.

Initiation of anti-tuberculosis treatment: prompt investigation and initiation of appropriate treatment to make those infectious non-infectious as fast as possible.

Optimize use of facility space: re-think use of available space and re-organize patient flow as to minimize the exposure to infectious patient. Consider facility design, construction of new wards or renovation of existing ones.

Screen and provide package of prevention and care interventions for HCW: educate and train HCW and offer isoniazid preventive therapy (IPT) for HIV-positive health workers.

Environmental Control Measures 2^nd priority

Environmental control measures can be added to administrative control measures to reduce the concentration of infectious particles in the air. Ideally though, risk of exposure to those particles should be eliminated through administration control measures.

Natural ventilation optimization: Maximizing natural ventilation should be considered before considering other ventilation systems (ie mechanical). Simple natural ventilation may be optimized by maximizing the size of the opening of windows and locating them on opposing walls. Wind-driven roof turbines (aka whirley birds) are a low-cost, low-maintenance technology that does not require electricity.

Artificial ventilation:

-- mixed mode: Well-designed, maintained and operated fans can help to obtain adequate airflow when natural ventilation alone cannot provide sufficient ventilation.

-- Mechanical: Mechanical technology is used where natural or mixed-mode ventilation systems cannot be implemented effectively, or where such systems are not possible due to local conditions (e.g. building structure, climate, regulations, culture, cost and outdoor air quality).

Air-disinfecting methods: These are upper room or shielded ultraviolet germicidal irradiation (UVGI) fixtures. UVGI are used when it is not possible for adequate ventilation to be achieved. This can be the case if there are climate changes (e.g. in winter or during the night) or because transmission of TB would pose a high risk of morbidity and mortality (e.g. in MDR-TB wards). This control does not provide fresh air or directional airflow.

Personal Protective Equipment 3^rd priority

This can supplement administrative and environmental control measures, but are not intended to replace them. When properly implemented, they can reduce the risk of inhaling infectious particles for health-care workers (HCWs) and other non-infected patients.

Particulate respirators: These are air -purifying masks that HCWs can wear to have additional protection from TB. They are particularly recommended when dealing with MDR or XDR-TB patients.

Face masks: (also known as surgical masks), can be worn by patients, especially those suspected of having infectious TB. Masks for TB patients are better than particulate respirators because they ensure proper couch etiquette.

Congregate Settings

Congregate settings are places where there is a high concentration of people in a shared space such as correctional facilities, military barracks, homeless shelters, refugee camps, dormitories and nursing homes. The TB infection control recommendations for congregate settings overlap greatly with those of health-care facilities. However, they tend to be less specific due to the diversity of congregate settings. Reduction of overcrowding in any congregate setting, especially in correctional services, is one of the most important measures for decreasing the transmission of TB in these settings. Also of importance are administrative control measures which focus on:

Cough etiquette and respiratory hygiene,

Early identification followed by

Separation of patient and initiation of appropriate treatment

Households

Households have a vital role in reducing TB transmission in the community. Community awareness and education campaigns should promote basic infection control behaviour-changes. These include:

Early identification of TB by going to a clinic to get screened and tested,

Adherence to treatment,

Education on and implementation of proper TB infection control measures (e.g. cough etiquette and respiratory hygiene) in the household,

Proper ventilation of homes,

Encouraging TB patients to spend as much time as possible outside, spend as little time as possible in congregate settings and public transportation, and

Sleeping alone in an adequately ventilated room if possible.

i WHO report 2011: Global Tuberculosis Control http://www.who.int/tb/publications/global_report/2011/gtbr11_full.pdf

ii Dr. L. Telisinghe, L. Odendal, Dr. C. Gouder, Dr. S. Parsons. Gap Analysis for South Africa's Round 10 GFATM: Infection Control

iii The Three I's for HIV/TB http://www.who.int/hiv/topics/tb/3is/en/