Infectious Diseases

Lyme disease is a bacterial infection transmitted by ticks. Lyme disease was first recognized in 1975, after researchers investigated why unusually large numbers of children were being diagnosed with juvenile rheumatoid arthritis in Lyme, Connecticut (USA), and two neighboring towns.

The investigators discovered that most of the affected children lived near wooded areas likely to harbor ticks. They also found that the children’s first symptoms typically started in the summer months coinciding with the height of the tick season.

Several of the patients reported having a peculiar skin rash just before developing arthritis symptoms, and many also recalled being bitten by a tick at the rash site. There is a single, localized skin lesion known as erythema migrans (EM) that develops around the place where the bite took place.

Further investigations resulted in the discovery that tiny deer ticks infected with a spiral-shaped bacterium or spirochete (which was later named Borrelia burgdorferi) were responsible for the outbreak of arthritis in Lyme. Ordinary “wood ticks” and “dog ticks” do not carry the infection.

The ticks most commonly infected with B. burgdorferi usually feed and mate on deer during part of their life cycle. The recent growth of the deer population in the northeast and the building of suburban developments in rural areas where deer ticks are commonly found have probably contributed to the increasing number of people with the disease.

The number of reported cases of Lyme disease, as well as the number of geographic areas in which it is found, has been increasing. Lyme disease has been reported in nearly all states in the USA, although most cases are concentrated in the coastal northeast, Mid-Atlantic States, Wisconsin, and Minnesota, and northern California.

Lyme disease is on the rise in Canada, yet diagnostics, treatment, physician and public awareness are largely inadequate. Reported cases in 2015 in Canada were 707. In Ontario, known endemic areas for Lyme disease are:

• Point Pelee National Park
• Rondeau and Turkey Point provincial parks
• Long Point peninsula, including Long Point Provincial Park and the national wildlife area
• Wainfleet bog near Welland on the Niagara peninsula
• Prince Edward Point
• parts of Thousand Islands National Park

Lyme disease is also found in large areas of Asia and Europe. Recent reports suggest that it is present in South America, too.

Symptoms of Lyme disease can include any of the following:

• skin rash
• headache
• fever or chills
• fatigue (tiredness)
• spasms or weakness
• muscle and joint pain
• numbness or tingling
• swollen lymph nodes

The two-tiered serological testing approach is recommended when testing a patient’s blood for antibodies against the bacterium causing Lyme disease. This approach is validated for use in Canada and includes:

• an enzyme immunoassay (EIA) screening test
• a confirmatory Western blot test (if the EIA is positive or equivocal)

TB was once a widespread disease that killed hundreds of thousands of people throughout history. The old term of it was called Consumption, because of the way it devoured the body after infection.

In Canada, the risk of developing TB is very low. Still, there are about 1,600 new cases of TB reported in Canada every year, with a steady decrease over the past 30 years.

This disease was virtually wiped out with the help of antibiotic revolution developed in the 1950s, but the disease has resurfaced in potent new forms, multidrug-resistant TB and extensively drug-resistant TB. Today, these new and dangerous forms of the disease have created a public health crisis in many large cities worldwide. If you have TB, in its active or latent state, you must seek medical treatment immediately.

Tuberculosis, commonly known as TB, is a bacterial infection that can spread through the lymph nodes and bloodstream to any organ in your body. It is most often found in the lungs. Most people who are exposed to TB never develop symptoms because the bacteria can live in an inactive form in the body. But if the immune system weakens, such as in people with HIV or elderly adults, TB bacteria can become active. In their active state, TB bacteria cause death of tissue in the organs they infect. Active TB disease can be fatal if left untreated.

Because the bacteria that cause tuberculosis are transmitted through the air, the disease can be contagious. Infection is most likely to occur if you are exposed to someone with TB on a day-to-day basis, such as by living or working in close quarters with someone who has the active disease. Even then, because the bacteria generally stay latent (inactive) after they invade the body, only a small number of people infected with TB will ever have the active disease. The remaining will have what’s called latent TB infection, they show no signs of infection and won’t be able to spread the disease to others, unless their disease becomes active.

If you have active TB disease, you may have any of these symptoms:

• Overall sensation of feeling unwell
• Cough, possibly with bloody mucus, lasting more than 2 weeks
• Fatigue; weakness
• Shortness of breath; chills
• Weight loss
• Low-grade fever
• Night sweats

Chest pain when breathing

Mononucleosis, often referred to as “mono,” is a very common viral illness. About 90% of people over 30 have been infected with it, probably during early childhood, and have antibodies to the virus in their blood.

When mono strikes young children, the illness is usually so mild that it’s not noticed or passes as a common cold. When it occurs during adolescence or adulthood, however, the disease can be much more serious.

Mono usually comes on over a few days. It begins with flu-like symptoms (fever, headache, and general malaise). After a few days, the lymph glands begin to swell, although this symptom is not noticeable in everyone. Swollen glands of the neck are especially typical of mono. Most people develop a sore throat, which can be very severe, with inflamed tonsils. A fever, no higher than 40C, also can develop and may last up to three weeks.

Some people, particularly those who take the antibiotic amoxicillin, may develop a red rash all over the body. Others may notice red spots or darkened areas in the mouth that look like bruises. In about 50% of all cases, the spleen becomes enlarged, which may cause an area in the upper-left abdomen to become tender to the touch.

In most cases, mono mildly affects the liver. Only a few individuals with mono develop jaundice, a yellowing of the skin and eyes caused by an increase of liver protein in the blood. In rare cases of mono, the liver fails.

The majority of cases of mono are caused by the Epstein-Barr virus, named after the two British researchers who first identified it in 1964. A common member of the herpes family of viruses, the Epstein-Barr virus is spread primarily through the exchange of saliva, which is why mono is sometimes known as “the kissing disease.” Coughing or other contact with infected saliva can also pass the virus from one person to another.

Other major complications that can develop from mono include rupturing of the spleen, low blood platelet count, swelling of the lining of the brain or spinal cord, or inflammation of the brain itself. These complications are extremely rare.

Most people who come down with mono feel much better within two or three weeks, although fatigue may last for two months or longer. Some people feel the disease lingers for a year or so.

Influenza is a viral infection that attacks your respiratory system – your nose, throat and lungs. Influenza, commonly called the flu, is not the same as stomach “flu” viruses that cause diarrhea and vomiting.

For most people, influenza resolves on its own, but sometimes, influenza and its complications can be deadly. People at higher risk of developing flu complications include:

• Young children under 5, and especially those under 2 years
• Adults older than 65
• Residents of nursing homes and other long-term care facilities
• Pregnant women
• People with weakened immune systems
• People who have chronic illnesses, such as asthma, heart disease, kidney disease and diabetes
• People who are very obese, with a body mass index (BMI) of 40 or higher

Initially, the flu may seem like a common cold with a runny nose, sneezing and sore throat. But colds usually develop slowly, whereas the flu tends to come on suddenly. And although a cold can be a nuisance, you usually feel much worse with the flu.

Common signs and symptoms of the flu include:

• Fever over 38C
• Aching muscles, especially in your back, arms and legs
• Chills and sweats
• Headaches
• Dry, persistent cough
• Fatigue and weakness in your muscles
• Nasal congestion
• Sore throat

The average human digestive tract is home to as many as 1,000 species of microorganisms. They are called commensals. Most of them are harmless under normal circumstances. But when something upsets the balance of these organisms in your gut, otherwise harmless bacteria can grow out of control and make you sick. One of the worst offenders is a bacterium called Clostridium difficile (also called C. difficile, or C. diff). As the bacteria overgrow they release toxins that attack the lining of the intestines, causing a condition called Clostridium difficile colitis.

Though relatively rare compared to other intestinal bacteria, C. diff is one of the most important causes of infectious diarrhea in Canada.

Most cases of C. difficile occur in patients who are taking certain antibiotics in high doses or over a prolonged period of time. It most commonly affects older adults in hospitals or in long-term care facilities.

c.difficile bacteria and their spores are found in feces. People can get infected if they touch surfaces contaminated with feces, and then touch their mouth. Healthcare workers can spread the bacteria to their patients if their hands are contaminated.

Symptoms include watery diarrhea, fever, loss of appetite, nausea, and abdominal pain/tenderness. In some circumstances, C. difficile can be fatal.

As with any infectious disease, frequent hand hygiene is the most effective way of preventing the transmission of healthcare associated infections. Hand washing with soap and water is important during C. difficile outbreaks and is one of the best defenses against further spread of the bacteria.

In recent years, C. difficile infections have become more frequent, severe and difficult to treat. In Canada, in 2011 were reported 3,181 cases with a mortality rate of 5%.

The common cold, including chest cold and head cold, and seasonal flu are caused by viruses.
Cold’s are caused by a tiny, living thing called a virus. More than 200 types lead to our misery, but the most common one is the rhinovirus, which brings on 10% to 40% of colds. The coronavirus is responsible for about 20% of cases, while the respiratory syncytial virus (RSV) and parainfluenza virus cause 10% of colds.
A cold begins when a virus attaches to the lining of your nose or throat. One myth that needs to get busted: Getting chilly or wet doesn’t cause you to get sick. But there are things that make you prone to come down with a cold. For example, you’re more likely to catch one if you’re extremely tired, under emotional distress, or have allergies with nose and throat symptoms.
Influenza, commonly known as the “flu,” is an extremely contagious respiratory illness caused by influenza A or B viruses. Flu appears most frequently in winter and early spring. The flu virus attacks the body by spreading through the upper and/or lower respiratory tract.
You might ask: What’s the difference between a cold and flu?
The common cold and flu are both contagious infections of the respiratory tract caused by viruses. Although the symptoms can be similar in nature, flu is much worse. A cold may drag you down a bit, but the flu can make you trembling at the very thought of getting out of bed.
Congestion, sore throat, and sneezing are common with colds. Both cold and flu bring coughing, headache, and chest discomfort. With the flu, though, you are likely to run a high fever for several days and have body aches, fatigue, and weakness. Symptoms of the flu also tend to come on sharply. Usually, complications from colds are relatively minor, but a severe case of flu can lead to a life-threatening illness such as pneumonia.
More than 100 types of cold viruses are known, and new strains of flu evolve every few years. Since both diseases are viral in nature, antibiotics cannot control the cold or flu. Remember: Antibiotics only treat bacterial infections!

At the end of 2014, the estimated number of persons living with HIV in Canada was between 63,400 and 87,600. It is estimated that 1 in every 5 Canadians infected with HIV has not been diagnosed.
The World Health Organization’s Global Health Observatory provides data on HIV and AIDS around the world. It estimates that 35 million people were living with HIV at the end of 2013.
Human immunodeficiency virus, or HIV, is the virus that causes acquired immune deficiency syndrome (AIDS). The virus weakens to the brink of collapse a person’s ability to fight infections and cancer. People with HIV are said to have AIDS when they develop certain infections or cancers or when their CD4 (T-cell) count is less than 200. CD4 count is determined by a specialized blood test. Several specialized tests can also find antibodies to or genetic material (RNA) of the HIV virus; these tests are: ELISA, Western blot, PCR and IFA.
Having HIV does not always mean that you have AIDS. It can take many years for people with the virus to develop AIDS. HIV and AIDS cannot be cured. However, with the medications available today and the new improvements coming along, it is possible to have a normal lifespan with little or minimal interruption in quality of life.
AIDS is the more advanced stage of HIV infection. When the immune system CD4 cells drop to a very low level (<50), a person’s ability to fight infection is lost. In addition, there are several conditions that occur in people with HIV infection with this degree of immune system failure – these are called AIDS-defining illnesses. Examples of these opportunistic infections are:
✓ Candidiasis (thrush): a fungal infection in the mouth, throat, or vagina.
✓ Cryptococcus neoformans (Crypto): a fungus that can lead to meningitis, a serious inflammation of membranes surrounding the brain and spinal cord.
✓ Cytomegalovirus (CMV): a virus that causes eye disease and can lead to blindness. It can also cause severe diarrhea and ulcers.
✓ Herpes simplex: viruses that can cause severe genital or cold sores.
✓ Mycobacterium avium complex (MAC): a bacterium that can cause fevers, problems with digestion, and serious weight loss.
✓ Pneumocystis pneumonia (PCP): a fungus that can cause fatal pneumonia.
✓ Toxoplasmosis (Toxo): a protozoa that sometimes causes encephalitis, an inflammation of the brain.
✓ Tuberculosis (TB): a bacterial infection that attacks the lungs and can invade other organs. TB can lead to meningitis at its most severe.
A person gets HIV when an infected person’s body fluids (blood, semen, fluids from the vagina or breast milk) enter his or her bloodstream. The virus can enter the blood through linings in the mouth, anus, or sex organs (the penis and vagina), or through broken skin.
Common ways people get HIV:
✓ Sharing a needle to take drugs
✓ Having unprotected sex with an infected person
You cannot get HIV from:
✓ Touching or hugging someone who has HIV/AIDS
✓ Public bathrooms or swimming pools
✓ Sharing cups, utensils, or telephones with someone who has HIV/AIDS
✓ Bug bites