Infectious Diseases - Session 2

Cholera is an acute diarrheal disease. Do you know what diarrhea is? Diarrhea is a condition characterized by loose, watery stools that occur more frequently than usual. Cholera is caused by the bacterium Vibrio cholerae. These bacteria produce a toxin known as cholera toxin. Cholera toxin is responsible for the characteristic watery diarrhea associated with the disease.

Cholera is typically transmitted through the ingestion of contaminated water or food. The bacterium can survive in brackish water and estuarine environments. It can also be found in seafood harvested from contaminated waters. Additionally, person to person transmission can occur in crowded or unsanitary conditions, particularly during outbreaks.

The primary symptom of cholera is profuse watery diarrhea. It is often described as rice-water-stool due to its appearance. Other possible symptoms include vomiting, dehydration, muscle cramps, rapid heart rate and low blood pressure. In severe cases, dehydration can result in shock and death if not treated promptly.

The incubation period for cholera is typically short. It ranges from a few hours to five days after ingesting contaminated food or water. However, many infected individuals might not develop symptoms, yet can shed the bacteria in their feces and contribute to the spread of the disease. Cholera is diagnosed through laboratory tests. Stool culture or rapid diagnostic tests detect the presence of Vibrio cholerae bacteria. Clinical symptoms, such as severe watery diarrhea in an endemic area or during an outbreak, can also indicate a diagnosis of cholera.

The cornerstone of cholera treatment is rehydration therapy. It involves replacing fluids and electrolytes lost through diarrhea and vomiting. Oral rehydration solution is the preferred method for mild to moderate dehydration. Intravenous fluids might be necessary for severe cases. Antibiotics, such as azithromycin or doxycycline, can be prescribed to shorten the duration of symptoms and reduce the shedding of bacteria in stool.

Tuberculosis is a bacterial infection caused by Mycobacterium tuberculosis. Mycobacterium tuberculosis is a pathogen that primarily affects the lungs. It can also target other parts of the body such as the kidneys, spine and brain. It is one of the oldest known infectious diseases and remains a significant global health concern.

Tuberculosis spreads through the air, when an infected individual coughs, sneezes, speaks, or sings, releasing tiny infectious droplets containing the bacteria into the air. People in close-contact with someone infected with tuberculosis are at higher risk of contracting the disease. Individuals with weakened immune systems are at greater risk of developing active tuberculosis after being infected. Tuberculosis can be latent or active.

Tuberculosis symptoms can vary depending on whether the infection is latent or active. Latent tuberculosis infection means that the bacteria is in the body but are not causing symptoms and are not contagious. Active tuberculosis disease occurs when the bacteria become active and multiply. They cause symptoms and make the person contagious.

A persistent cough that lasts for more than three weeks is one of the hallmark symptoms of the active tuberculosis. The cough might produce sputum or phlegm, which can be bloody or tinged with blood. Chest-pain can occur due to inflammation of the lungs or the formation of tubercles within the lung tissue. Tubercles are small, rounded nodules.

Hemoptysis, or coughing up blood, can occur in advanced cases of tuberculosis. This occurs when the infection has caused damage to the lung tissue or blood vessels. People with active tuberculosis often experience persistent fatigue, including after getting adequate rest. This fatigue might be accompanied by weakness and a general feeling of malaise.

A low grade fever is common in the active tuberculosis. The body's immune response to the infection can cause a raise in body temperature. Profuse sweating, particularly during the night, is a characteristic symptom of the active tuberculosis. Night sweats can be severe and disrupt sleep.

Individuals with active tuberculosis can experience a significant loss of appetite, leading to unintentional weight loss. This weight loss can be rapid and substantial. As tuberculosis progresses and causes inflammation and damage to the lungs, it can result in difficulty in breathing, especially during physical activity. Abnormal breath-sounds, such as wheezing or crackles might be heard upon auscultation of the chest-area. These sounds indicate inflammation or fluid accumulation in the lungs.

Tuberculosis can cause enlargement of lymph nodes, particularly in the neck or underarms, as the body's immune system tries to contain the infection. Some individuals with tuberculosis can experience joint pain or swelling, especially if the infection has spread to the bones or joints. In rare cases, tuberculosis can affect the abdominal organs, leading to abdominal pain or discomfort.

Tuberculin skin test is carried out to diagnose tuberculosis. This involves injecting a small amount of a substance called PPD tuberculin into the skin of the forearm. A raised, red bump at the injection site after forty eight to seventy two hours might indicate tuberculosis infection. Blood tests and chest-x-ray can also help in diagnosing tuberculosis. Chest-x-ray helps in identifying abnormalities in the lungs caused by tuberculosis.

Sputum test can also be used to diagnose the tuberculosis. Sputum is the mucus coughed up from the lungs. Sputum test involves the examination of sputum under a microscope to check for the presence of tuberculosis bacteria. Tuberculosis is treatable and curable with antibiotics. The most commonly used drugs for the treatment of tuberculosis include isoniazid, rifampin, ethambutol and pyrazinamide. Treatment usually involves a combination of these drugs taken over several months.