If you have been following this column, you have become familiar with several important health issues that can affect seniors — diabetes, high blood pressure, dementia; the list goes on. Yet, there is another quiet killer on the loose, one that flies under the radar and seems accidental when it happens. It could be responsible for as many as one-third of all deaths in people 65 years and older. It can kill much faster than diabetes, heart disease and even cancer.

We are talking about infection.

Seniors are at high risk for infection, because the immune system becomes weakened with age. Chronic illnesses, too, can weaken the body’s ability to fight infection.

Older people are also more likely to become exposed to infection in hospitals and long-term care facilities.

To make matters worse, infection could be difficult to recognise in older adults. The typical signs and symptoms, such as fever, are often absent in seniors. Even laboratory tests are not always accurate — a high white blood cell count, usually seen with infection, may not occur in an older patient.

A change in mental status or decline in function may be the only presenting problem. Caregivers should also be on the lookout for loss of appetite, falls, weight loss or even a slight increase in breathing rate.

Urinary tract infections (UTIs) are the most common bacterial infection in older adults. Risk factors include enlarged prostate in men, hormonal changes in women and incomplete bladder emptying. If you have fever, pain with urination or cloudy urine, call your doctor. Antibiotics can often cure a UTI.

Pneumonia and flu, together, are the sixth leading cause of death in the United States. About 90 per cent of these deaths occur in adults 65 years and older.

The risk of bacterial pneumonia goes up with age. Reasons include decreased cough reflex, less elastic lung tissue and less active breathing. In the elderly, pneumonia can be difficult to recognise.

Caregivers should be ready to call a doctor if “something is not right” with the older adult. For example, a mental status change or new onset of rapid breathing may suggest infection. Antibiotics can treat bacterial pneumonia but a hospital stay could become necessary.

Influenza, or flu, is a significant cause of illness in older adults.

Of deaths resulting from influenza, 80 to 90 per cent occur in adults 65 years and older. Influenza often causes rapid onset of headache, fever, chills, muscle aches, cough and sore throat.

Yet, these symptoms may be blunted or even absent in the elderly. Most people recover within one week, but older adults may take longer to get better.

The elderly may also be at higher risk for complications, such as pneumonia, due to other chronic diseases and weakened immunity. Seek medical attention if you think you have the flu; several treatment options are available.

Shingles is a skin infection that is more common in seniors. The symptoms arise from reactivation of varicella virus, which has before been inactive. As immunity wanes with advancing age, the virus may escape from suppression and cause shingles. One can recognise shingles from skin lesions that progress from discrete patches of redness to grouped blisters that crust over within seven to ten days. These skin lesions can be quite painful. Antiviral medications are available for treatment and can shorten the length of the outbreak.

Most infectious diseases discussed in this article are preventable.

UTIs are preventable by limiting the use of urinary catheters, and providing topical oestrogen therapy for women and treatment of prostate hypertrophy for men.

Pneumonia vaccine significantly decreases the risk of invasive infection and death from pneumonia in older adults with a healthy immune system.

Flu shots target the strains of influenza A and B that are most likely to cause illness during a particular season. A timely vaccination can significantly reduce the risk of flu and its complications among elderly persons in home settings.

For caregivers, practising good infection control methods such as proper handwashing or the use of hand-sanitising gels, whenever they are around an elderly person, is essential.

Centres for disease control also have recommendations on disinfection, with an EPA-registered disinfectant, of environmental surfaces in the patient care areas at healthcare facilities. I think these are worth following.

•Mike Serebrennik is a physician by training and now a full-time entrepreneur, investor and writer. He is also a director of product development and sourcing at Lighthouse Medical Supplies, Ltd, a local company dedicated to helping patients and healthcare providers lower the cost and increase the quality of care.