TB Preventative Therapy (TPT):

exp date isn't null, but text field is

Approximately 5-15% of adults with latent TB infection (LTBI) develop active TB disease during their life. Provision of preventive treatment has proven itself as an effective intervention to avert the development of active TB disease, with efficacy ranging from 60% to 90%. The likelihood of progression of TB infection to active disease depends on bacterial, host, and environmental factors. In high TB prevalence and resource-limited settings such as Zimbabwe, the following four target populations are recommended for preventive treatment: (1) people living with HIV, (2) children less than five years of age, who are household contacts of bacteriologically confirmed pulmonary TB cases, (3) all household contacts of bacteriologically confirmed pulmonary TB cases with TB infection and (4) clinical risk groups (such as patients initiating anti-tumor necrosis factor [TNF] treatment, receiving dialysis, preparing for solid organ or bone marrow transplants and those with silicosis).

HIV infection is the strongest risk factor associated with the development of active TB, with up to 40% of patients progressing to TB disease after exposure. Treatment of LTBI in people living with HIV (PLHIV) reduces the risk of TB disease development by up to 35% and plays a synergistic role in further risk reduction when used with antiretroviral therapy (ART). Children less than five years old are a particularly vulnerable population due to their higher risk of progressing to active TB disease and their greater risk of developing more severe forms of TB (including TB meningitis and disseminated TB), in addition to the difficulty of confirming the diagnosis, given the paucibacillary nature of their disease. Together, these factors result in high TB-associated child morbidity and mortality. As diagnosing active TB disease in young children is a challenge, averting new paediatric TB cases by delivering preventive treatment is of strategic importance to decrease the overall burden of paediatric TB disease.

People living with HIV are 20 to 37 times more likely to develop active TB from LTBI than those without HIV, making HIV infection the strongest risk factor for TB disease. TB is responsible for more than a quarter of deaths of people living with HIV. IPT has been shown to reduce the incidence of TB in HIV-infected people with LTBI by 33-62%.

Among PLHIV, TPT is likely to provide protection against the risk of developing TB by decreasing the risks of:

  • Progression of recent infection
  • Reactivation of latent Tuberculosis

In addition, TPT programs decrease the rate of TB in the community and improve TB control.Inclusion Criteria for Children

  1. Negative TB screening (no current cough, no fever, good weight gain) or evaluation found no active TB. And child fits into one of the following categories:
    • Routinely: All HIV exposed and HIV infected children between the ages of 12 and 15 years, regardless of contact history
    • After any contact with TB: All HIV exposed; HIV infected children above 15yrs and HIV uninfected children less than 5yrs having had contact with any case of TB
    • Post TB treatment: All HIV exposed and HIV infected children <15 years of age immediately following the successful completion of TB treatment.
  2. Caregiver demonstrates a good understanding of TPT and no known risk factors for poor adherence are identified.

NB: Investigations for TB should be done according to national guidelines.

Inclusion Criteria for Adults and Adolescents including Pregnant Women (≥15 years)

  1. ALL CONFIRMED HIV INFECTED ADULTS who are:
    • On ART for more than 3 months or
    • Post TB treatment (immediately following the successful completion of TB treatment).
    • Contacts of PTB
    • No signs or symptoms of TB (Based on adult TB Screening guidelines)

Tuberculosis Screening Tool

  1. Does the patient hove any of the following:
    1. Current cough (if HIV +) or cough of greater than 1-2 weeks?
    2. Fever
    3. Night sweating
    4. Loss of weight (>10%) or a BMI of less than 17Kg/m2
  2. CXR for TB High Risk Groups if available
  3. Collect a sputum specimen for Xpert MTB/Rif assay (GeneXpert) for any person who has one or more or the above symptoms or an abnormal CXR .
    • No signs or symptoms of Tuberculosis (Based on the adult TB screening criteria)
    • Good understanding of TPT and willingness to adhere

Dosages for lsoniazid:

  • The recommended dose of INH in adults and adolescents is 5mg/kg/day to a maximum of 300mg/day.
  • The recommended dose of INH in children is 10mg/kg/day (with a daily maximum dosage not supposed to exceed 300mg). Refer to the table below for guidance on the recommended weight bands versus INH to be administered:
  • INH and Rifampicin can be used for TPT in children
  • All patients on TPT must be given pyridoxine

Dosage of lsoniazid per weight

Weight range (kg)

Number of 100mg tablets of INH to be administered per dose (total dose 10mg/kg/day)

Dose given (mg)

≤5

½ tablet

50

5.1-9.9

1 tablet

100

10-13.9

1 ½tablet

150

14-19.9

2 tablets

200

20-24.9

2 ½tablets

250

≥25

3 tablets or one adult tablet

300

Three months of daily rifampicin and isoniazid preventive therapy (RH 75/50) for children

Weight bands

Number of Tablets

RH 75/50 mg

4-7.9 kg

1

8-11.9 kg

2

12-15.9 kg

3

16-24.9 kg

4

Supplemental pyridoxine for children

Weight bands

Number of tablets of

pyridoxine 50mg

1-13.9kg

¼

14-24.9kg

½

≥25kg

Go to adult dosages and preparations

Pyridoxine dosage for adults and children

Adults: pyridoxine (vitamin B6): 25mg/day

Children: pyridoxine 25mg/day

Note: Liver toxicity symptoms should be apparent e.g. any one on TPT who develops poor appetite, nausea, or vomiting should be assumed to have liver toxicity until proven otherwise and should be referred to hospital for same day admission to investigate possible liver toxicity