How many children get TB?
The World Health Organisation (WHO) estimates are that 1 million children (<15 years) currently suffer from TB worldwide, and that 239,000 die each year. This is the estimate for HIV negative children. Children who have TB and who are also HIV positive when they die (i.e. they have TB/HIV co-infection), are internationally classified as having died from HIV. In 2006 National Treatment Programs were asked by WHO to record and report TB in children, dividing them into two age groups (0 - 4) years and (5 - 14) years.
There is some more information about the number of deaths from TB in children.
A 2016 study estimated that 67 million children have latent TB.1“2 million children infected by drug resistant TB”, Hindustan Times, 2016 www.hindustantimes.com/india-news/2-million-children-infected-by-drug-resistant-tb-study/story-010sNNxcdVMWYGgu2NNHKO.html
70-80% of children with TB have the disease in their lungs (pulmonary TB). The rest are affected by TB disease in other parts of their body (extra pulmonary TB).2“Childhood TB: Training Toolkit”, WHO, Geneva, 2014 www.who.int/tb/challenges/childtbtraining_manual/en/
In high burden TB settings it has been noted that 15-20% of all TB cases are among children, whereas in low burden TB settings it is estimated that 2-7% of all TB cases are among children.3“Childhood Tuberculosis Roadmap”, 11th November 2012 www.stoptb.org
Drug resistant TB
Drug resistant TB is also an issue in children. It is estimated that more than 30,000 children become sick every year with strains of multdrug-resistant (MDR-TB)4MDR-TB in children : A Q & A with PIH’s Dr Mercedes Becerra www.pih.org/ Also, an RNTCP survey in India, found that 9% of children with TB were already resistant to rifampicin, before they started treatment. This means that they had become infected with drug resistant TB.5“9% children suffering from TB resistant to key drug: Study shows”, Ekatha A, Times of India, 17th Nov 2015, http://timesofindia.indiatimes.com/india/ Another study estimated that globally 2 million children were infected with drug resistant TB, requiring the treatment every year of up to 25,000 cases of MDR TB in children.6“2 million children infected by drug resistant TB”, Hindustan Times, 2016 www.hindustantimes.com/india-news/2-million-children-infected-by-drug-resistant-tb-study/story-010sNNxcdVMWYGgu2NNHKO.html
How does a child get TB?
A child gets TB in basically the same way as an adult, which is by inhaling TB bacteria which are in the air as a result of being released into the air by someone with active TB. The source of infection for children is usually an adult in their household who has active TB, is coughing and is infectious. There have though also been occassional instances of children being infected in a communal setting such as a school. The source of infection can be either another child or an adult.
Once the TB bacteria have been inhaled they may reach the lungs, where they can multiply and then spread through the lymph vessels to nearby lymph nodes. The child’s immune response then develops a few weeks after this primary infection. In most children their immune response stops the TB bacteria from multiplying further although there may continue to be a few dormant bacteria.7“Guidance for national tuberculosis programmes on the management of tuberculosis in children” WHO 2006 www.who.int/maternal_child_adolescent/
However in some cases the child’s immune response is not strong enough to stop the multiplication of the bacteria, and TB disease then develops. The risk of progression to TB disease is greatest when the child is less than four years old, and to a lesser extent when they are less than ten years old. There is also a greater risk of progression in children who have a compromised immune system, for example because they are HIV positive.
Children who develop TB disease usually do so within two years of first being infected. A small number of older children develop TB later, either due to reactivation following a period when the TB bacteria have been dormant, or as a result of reinfection.
Some children are at greater risk of getting TB than others and these include:
- A child that lives in the same household as a person who has been recently diagnosed with smear positive TB
- A child less than 5 years old
- A child with HIV infection
- A child with severe malnutrition.
There is a two way link between nutrition & TB. TB makes malnutrition worse and malnutrition makes TB worse.
How do you diagnose TB in children?
This is quite difficult as children are less likely to have obvious symptoms of TB, and samples such as sputum are more difficult to collect from young children. Even when sputum can be collected, it may have very few TB bacteria in it (paucibacillary smear-negative disease).
It is recommended that evidence in the following categories is collected and carefully considered before a diagnostic decision is made.8“Out of the Dark: Meeting the Needs of Children with Tuberculosis”, MSF Access to Essential Medicines October 2011 www.msfaccess.org/
|Type of evidence||Evidence to be collected|
|Clinical||Careful history (including TB contacts; symptoms consistent with TB), Physical examination (including growth assessment), HIV testing (in high HIV prevalence areas)|
|Non-microbiological||Tuberculin skin testing (TST), Other investigations relevant for pulmonary or extra pulmonary TB (e.g. X-rays)|
|Microbiological||Bacteriological confirmation whenever possible|
What are the symptoms of TB?
As with adults the symptoms of TB depend on the type of TB that the child has as well as their age.9“Roadmap for Childhood Tuberculosis”, 2013 www.who.int/tb/publications/tb-childhoodroadmap/en/ The most common type is pulmonary TB but extra pulmonary TB occurs in approximately 20-30% of all cases in children. Disseminated TB such as TB meningitis particularly occurs in young children less than 3 years old. Miliary TB is another name for disseminated TB.
Infants and young children are at particular risk of developing severe, disseminated and often lethal disease, which may show itself as TB meningitis or miliary TB. Adolescents are at particular risk of developing adult type disease (i.e. they are often sputum smear positive and highly infectious).10“Out of the Dark: Meeting the Needs of Children with Tuberculosis”, MSF Access to Essential Medicines October 2011 www.msfaccess.org/
In children with pulmonary TB the commonest chronic symptoms are a chronic cough that has been present for more than 21 days, a fever, and weight loss or failure to thrive.
TB diagnosis in practice
“Most of the time you make a decision based on your clinical observation. Should I or should I not treat this child for TB. And making that decision you’re talking about the life of a child, so it is not something to be taken lightly.”
Dr Bern-Thomas Nyang’wa, MSF TB Implementer
Sometimes it is necessarily to use the test results from the adult who is believed to have passed TB on to the child, to ensure that the child is properly diagnosed and treated.
How do you treat TB in children?
In the same way as TB treatment is provided for adults, TB treatment for children involves a child taking a number of different drugs at the same time for several months. There is now improved treatment for children which is easier for the child to take.
How do you prevent TB?
The main way that TB is prevented in children is by the use of the BCG vaccine.
TB can also be prevented in children by diagnosing and treating cases of active TB among adults. It is usually adults, particularly adults in the same household, who spread TB to children.
Children with TB are usually not infectious, and so will usually not pass on TB to either other children or adults although there have been occassional instances of this happening.11“Childhood TB: Training Toolkit”, WHO, Geneva, 2014 www.who.int/tb/challenges/childtbtraining_manual/en/ If a child is known to have TB and is receiving treatment then individual advice must be obtained from an experienced doctor regarding when the child can return to school.
Access to care must be provided at the community level. Screening households where an adult is diagnosed with TB to see if children have been exposed in the home must become the standard implemented everywhere. Where this approach has been piloted, 72 percent of at-risk children have been able to receive preventative treatment, up from less than five per cent previously.