TB is difficult to diagnose in children because it is hard to confirm the diagnosis by culture even where laboratory facilities are good. The presence of HIV makes the task even more difficult, resulting in some children being misdiagnosed as having TB and given treatment, while others with TB may be falsely negative and not receive treatment.

The current international TB control strategy focuses on active pulmonary TB—the source of most TB infection in children—but does not address children and adolescents as vulnerable sub-groups. Furthermore, vaccination of infants with BCG is no longer believed to prevent active TB in adulthood, although it can protect children from the disseminated forms of the disease, for example, tuberculosis meningitis.

Children are exposed to TB primarily through contact with infectious adults—with special risk in high TB-HIV settings—and will continue to be at risk for TB as long as those adults remain untreated. Curing TB and preventing its spread in the wider community is thus one important strategy to reducing children s vulnerability to TB.

No vaccine yet exists that is truly effective against pulmonary disease. BCG vaccine (Bacillus Camille Guerin) was invented in 1921. It is useful in preventing certain types of TB, namely miliary and meningeal tuberculosis occurring in the first year of life, but is not effective in preventing the development of pulmonary TB in adulthood.

Children are also vulnerable to the direct and indirect impacts of other family members having TB. Already marginal households that lose income or incur debt due to TB will experience even greater poverty as budgets are cut and assets sold. If their primary care giver is ill or is preoccupied with caring for other ill family members, the child’s care and education may be neglected. If the principal family provider is ill and cannot work, children risk malnutrition, which increases susceptibility to TB and brings with it lifelong deleterious effects on both health and education. Children are especially vulnerable if their mother becomes sick and dies. There is a strong correlation between maternal survival and child survival to age 10. One study in Bangladesh revealed that whereas a father’s death increased child mortality rates by 6 per 100 000 for both boys and girls, a mother’s death was associated with increases of 50 per 100 000 in sons and 144 per 100 000 in daughters.

Children in households with TB may also be taken out of school or sent to work. Both scenarios deprive them of their right to education and put them in situations that may expose them to more prolonged contact with persons with active TB. In rural Uganda, for example, 32 patients were interviewed about the economic costs of TB. Five of their children had had to be withdrawn from school because fees could not be paid. Even if not removed from school, children from poor or marginalized communities where poor nutrition and ill-health prevail have a below-average school enrolment and attendance rate and, as a result, lower-than-average educational attainment. Lack of education correlated negatively with access to health services, and the neglect of the right to education on children’s current and future health can be profound.

Reasons why children have a high risk of developing active TB disease

The immune system of young children is less developed than that of an adult and the risk of developing active TB disease is therefore higher in young children. The chance of developing TB disease is greatest shortly after infection. When children present with active tuberculosis disease their family members and other close contacts should be investigated for TB to find the source of the disease and treat them as necessary.

Therefore a good TB control programme, which will ensure early diagnosis and treatment of adults with infectious form of TB is the best way to prevent TB in children.

In HIV infected children the risk is very high to develop TB meningitis with often devastating results for the child like deafness, blindness, paralysis and mental retardation as some of the consequences.

Tuberculosis and malnutrition often go together, and a child with TB disease may present as failure to gain weight with loss of energy and a cough lasting for more than three weeks.

Tuberculosis immunology in children: Diagnostic and Therapeutic challenges and opportunities

Tuberculosis (TB) is one of the most important causes of infectious morbidity and mortality worldwide. Young children are more likely to develop severe disease from the causative agent Mycobacterium tuberculosis. These clinical observations likely reflect fundamental differences in the immune systems of young children and adults. Essential to effective TB immunity are functioning macrophages, dendritic cells, strong Th1-type T-cell immunity and a relative absence of Th2-type T-cell immunity. Critical differences between adults and children relevant to TB immunity include deficiencies in macrophage and dendritic cell function, deficiencies in the development of Th1-type T-cells in response to pathogens, and the propensity for infants and young children to develop Th2-type CD4+ T-cells in response to immunogens. In this article, knowledge about the requisite components of protective immunity, differences between the immune systems of children and adults relevant to pediatric tuberculosis, M. tuberculosis-specific T-cell immunity in children, and potential application to immunodiagnostics and vaccine development will be reviewed.

Identifying TB in Children

Vaccination has been the primary TB prevention method in children. In fact, BCG is the most widely used vaccine in the world. Although it is relatively ineffective in preventing infectious forms of TB, it does prevent more serious forms of TB disease in children. Nevertheless, a quarter of a million children still develop TB every year: Particularly vulnerable to infection from household contacts, many of them have been infected in their own homes, by parents or other relatives with active, infectious TB. Diagnosis of TB in children is notoriously difficult, as the early symptoms and signs are easily missed. Most national TB control programmes have little in the way of services for children. TB in the family also has a serious impact on children. In India alone, 300,000 children are taken out of school every year to care for a parent sick with TB.

Tuberculosis (TB) is a serious infection caused by the bacteria Mycobacterium tuberculosis. Unfortunately, the incidence of tuberculosis has been increasing in recent years and there are an increasing number of cases of multi-drug resistance tuberculosis.

Routine testing for TB with a tuberculin skin test is now only recommended in children who are at high risk for having the illness. Risk factors include being exposed to an infected adult, contact with someone who has been in prison, contact with the homeless, and travel to countries with a high rate of tuberculosis, including Mexico, India, Vietnam, China, Philippines, and many countries in Latin America, Asia, the Middle East and Africa. Adopted children from any high risk area should also be tested, including Romania and Russia.

Also, all contacts of a person with a positive tuberculin skin test should also be tested. Even with a negative test, some younger children may need a chest x-ray and treatment if they were recently exposed to someone with tuberculosis and that person was thought to be contagious. Negative skin tests may need to be repeated in three months.

Testing for tuberculosis is by the tuberculin skin test, which is usually a Mantoux test with 5 units of purified protein derivative (PPD). Other forms of testing are not recommended. After being placed on a child's forearm, the tuberculin skin test should be read 48-72 hours later by experienced personnel. Interpretation depends not only on the type of reaction after the test, but also the child's risk of having tuberculosis. A child over 4 years of age with no risk factors may have a small reaction (5-14mm of induration) and not have a tuberculosis infection, while a child who has had close contact with someone with tuberculosis will be considered infected even with a very small reaction (greater than or equal to 5mm induration). Even children who have received the BCG vaccine can have skin testing done.

Children exposed to someone with tuberculosis will likely develop a positive tuberculin skin test about 2-12 weeks later. Some children, especially with immune system problems, can have a negative tuberculin skin test and still be infected with tuberculosis.

Most children with tuberculosis do not have symptoms. They have a positive PPD, a normal chest x-ray and no signs or symptoms of tuberculosis and are said to have a tuberculosis infection or a latent tuberculosis infection. Even though they do not have symptoms, people with a positive PPD need treatment, which usually consists of 9 months of isoniazid. If the infection is thought to be resistant to isoniazid, then rifampicin may be used for 6 months.

Children with symptoms of tuberculosis, a positive tuberculin skin test and/or a positive chest x-ray are said to have tuberculosis disease. This is more serious than just have a tuberculosis infection. If untreated, children with a tuberculosis infection can develop tuberculosis disease (usually within six months to two years), with symptoms including a cough, fever, night sweats, swollen glands, decreased appetite and activity, weight loss and difficulty breathing.

In addition to the tuberculin skin test, children with tuberculosis disease should have additional testing to try and culture the tuberculosis bacteria so that it can be determined which drugs the infection is sensitive to. Because tuberculosis is a slow growing bacteria, culture can take as long as ten weeks for a final result. To obtain a culture, unless the child has a productive cough and can produce a sputum sample, cultures may need to be obtained from a gastric aspirate in the early morning. Children with tuberculosis disease should also be tested for HIV.

In the lungs, tuberculosis causes the formation of cavitary lesions, pleural effusions and enlarged lymph nodes. These can usually be seen on a chest x-ray. In addition to the pulmonary symptoms described above, tuberculosis can also cause meningitis and infections of the ear, kidney, bones and joints.

Treatment of tuberculosis is with long-term use of a combination of antibiotics, depending on whether or not it is resistant to commonly used drugs. Treatment should be coordinated with the local health department and/or a pediatric infectious disease specialist.

Treatments for tuberculosis disease involving the lungs consists of 6 or 9 months regimens including isoniazid, rifampin and pyrazinamide. Another drug, either ethambutol or streptomycin may be needed for multi-drug resistant TB. Extrapulmonary tuberculosis (either meningitis or infections of the bones or joints) usually includes a 9-12 month regimen of three or four drugs, depending on resistance.

Most people with tuberculosis disease need to undergo directly observed therapy (DOT) in which treatment is observed by a health care worker, either in person or sometimes by video.

Adults with tuberculosis disease are contagious for at least a few weeks after beginning proper treatment. Children with tuberculosis disease are not as contagious, because they usually have smaller lung lesions and do not cough as much.

Children at greater risk for Tuberculosis

Some groups of children are at greater risk for tuberculosis than others. These include:

• Children living in a household with an adult who has active tuberculosis
• Children living in a household with an adult who is at high risk for contracting TB
• Children infected with HIV or another immunocompromising condition
• Children born in a country that has a high prevalence of tuberculosis
• Children from communities that are medically underserved