What is Tuberculosis (TB)?
Tuberculosis is an infection primarily of the lungs and may later involve any part of the body. It is caused by a bacteria of the genus mycobacteria, species mycobacterium tuberculosis and other species. Most of the species cause disease in humans and a few cause diseases in animals as well. It is common in countries with a low socioeconomic status where the living environments lack adequate space, ventilation and lighting.
How does it spread?
Tuberculosis is transmitted from one person to another through droplets produced when a person with lung or airways tuberculosis coughs, and sneezes. They may be produced when one shouts or sings. After the particles are produced, they may linger in the air for many hours and are inhaled by another susceptible person then they settle in the lungs and cause the disease.
Whether a person develops Tuberculosis after exposure depends on the intensity of the exposure, their immunity or ability to fight infections, and their vaccination status.
How the disease progresses
Once exposed and the child inhales the tuberculosis bacteria, they settle in the lungs. Usually, the body mobilizes certain cells in the body to clear them. This fight between the cells and the bacteria results in tissue damage and thus the primary infection in the lungs. Many times, the story ends there and the bacteria remain latent in the lungs. They may be controlled by the body’s immune system and settle in the local lymphnodes or spread through the bloodstream to other parts of the body. The child develops the typical symptoms when the disease damages the lungs or spreads to other parts of the body. Few of the bacteria may remain dormant in the body and one may develop the disease many years later. This depends on the body’s age and immune status. The immune status may be affected by other diseases like Human Immunodeficiency Virus infection or others like Diabetes or cancer. Some medications may also suppress the immunity and bring about dormant or latent tuberculosis.
Other than the lungs, the other parts of the body the infection may affect are lymphnodes, bones, coverings of the brain and other organs.
According to the World Health Organization estimates that about one-third of the world population has been infected with Tuberculosis though not all of these people progress to the disease. Each year about 10 million people worldwide fall ill with Tuberculosis and about 1 in 5 die of the disease. About 10 per cent of these infections are in children. Kenya is among the TB high burden countries in the world. Ministry of Health Kenya reported that in 2015 a total of 81,518 cases of all forms of tuberculosis occurred, 8.5% being in children.
Making a diagnosis relies on a good history, examination and investigations. Known close contact with an adult with lung tuberculosis in the preceding 2 years is very important information in making a diagnosis. Clinical features may include cough for longer than a week, fever and night sweats, less playfulness and poor weight gain or weight loss. An examination may reveal Fever, wasting, noises in the lungs or difficulties in breathing. Other features of widespread TB include enlarged lymphnodes, Meningitis signs, Bone pains or swelling, and the collapse of vertebral bones or abdominal swelling among others.
The investigations used to make a diagnosis include expectorated sputum testing, imaging of the affected body part with x-rays, ultrasound, CT scans or MRI scans. Others include skin testing and tests of other specimens depending on the site infected.
Genexpert is a molecular test preferred for the diagnosis of TB in children using an expectorated sputum specimen. It is also used to test for possible resistance of the infection to Rifampicin, one of key medications used in the treatment of TB.
All children suspected to have Tuberculosis must have their HIV status known because it impacts the management.
There are other diseases which can be confused with TB and a child with suspected Tb needs to be assessed well for these diseases. They include Asthma, Enlarged adenoids, Allergic airway disease, Foreign body in the airways, Reflux, and heart disease among others.
Children respond well to standard treatment for TB when started early. HIV infected children do not respond as well as those who are HIV negative. Weight is used to monitor response and should be determined at each visit to the hospital. Treatment aims to cure the child, prevent complications and death, prevent a recurrence, prevent the development of resistance to the medications used and prevent spread.
The first-line treatment regimens consist of a combination of medications for effective clearance of the mycobacteria from the body. They are given in two phases, Intensive and Continuation Phases. The duration of treatment depends on the site of the infection, 6 months for all forms of TB except that affecting the coverings of the brain, bones and joints which is treated for 12 months. For effective treatment, there should be adherence to the treatment regime without missing a dose and attending follow up clinics for monitoring and management till after the treatment duration.
Children who are infected with TB and are HIV positive do not respond well to TB treatment and they require expert follow up to tailor the medications used. The medications used for both of these diseases interact with each other and may affect their effectiveness as well as increase the propensity to side effects.
Certain types of mycobacteria develop resistance to the usual combination medications used for TB and are labelled as either Drug-Resistant TB or Multidrug-resistant TB (MDR TB) or Extensive Drug-resistant TB (XDR TB). These are treated with complex regimens with second or third line antituberculous medications. They require experts in their treatment and follow up.
Prevention of TB
Early diagnosis and treatment of TB are very important in the prevention of its spread to other persons. Measures to reduce the concentration of droplets in the air in rooms by improving ventilation, aeration and lighting of such rooms. Other measures include the use of personal protective equipment like masks for health care workers attending to patients with TB and other infection control and prevention measures. Any contacts of patients with open or lung TB need to be evaluated for infection and treated as necessary.
Children should be routinely immunized against TB at birth by using the BCG vaccine. This vaccine does not prevent infection but prevents severe forms of tuberculosis.
Improvement of nutritional status improves children’s immune systems to reduce the chances of contracting TB.