Find out about potential national guidance or programme concerning tuberculosis.
Even if tuberculosis has become rare in many countries it is important to bear the possibility of the disease in mind and start diagnostic investigations without delay if tuberculosis is suspected.
Pulmonary tuberculosis and lymph node tuberculosis are the most common forms of the disease.
In practice, only pulmonary tuberculosis is infectious and triggers infection tracing. In extrapulmonary tuberculosis, if aerosolization of any excretion into the air has taken place (e.g. when spraying an abscess or a lymph node with discharge), infection tracing may be warranted.
Epidemiology
In 2018 there were 226 diagnosed tuberculosis cases in Finland (4.1/100 000). 67% were pulmonary tuberculosis, of which 33% were sputum staining positive.
As tuberculosis has become rarer the relative proportion of infections caused by environmental (also "non-tuberculous" or "atypical") mycobacteria has increased.
Risk groups for tuberculosis
Near contacts to a patient with staining-positive pulmonary tuberculosis
Elderly persons (over 75 years of age)
Persons who have alcohol or drug abuse problems or who are socially exluded
Refugees and immigrants from countries with high incidence of tuberculosis
Patients with certain other diseases (HIV, diabetes, rheumatoid arthritis, malignancy, silicosis, severe renal failure)
Most commercial tests have only been validated and licensed for DNA isolated from staining-positive sputum and/or culture. The tests usually are less sensitive for staining-negative sputum and other samples.
It is advisable always to perform some DNA rapid test on a staining-positive sample in order to quickly check whether the causative agent is M. tuberculosis or an atypical mycobacterium.
A rapid test may also reveal potential drug resistance genes for rifampicin and isoniazid.
Specimens
Body excretions and fluids: sputum, urine, blood, CSF, pleural fluid, bone marrow, wound discharge
Needle and aspiration samples
Tissue samples (in a clean tube without formaldehyde)
The culture takes 4-6 weeks.
Findings in tissue samples
Epitheloid cells
Langhans' giant cells
Caseous necrosis
Pulmonary tuberculosis
Symptoms
May be asymptomatic.
General symptoms: fatigue, poor appetite, weight loss, fever bouts, night sweats
Pulmonary symptoms: prolonged cough and mucus production, haemoptysis
Gradation of diagnostics and treatment
Primary health care is responsible for the tasks listed below.
Identification of possible tuberculosis
Initiation of diagnostic investigations and referral to treatment
Chest x-ray is taken without delay. If there is sputum production, the collection of sputum samples should be started right away in the primary care (tuberculosis staining and culture 3 times).
If tuberculosis is diagnosed or strongly suspected, the patient is referred to specialist care without delay.
If a sputum sample stains positive and chest x-ray shows a clear cavity, the hospital should be contacted beforehand by phone and arrangements for isolation treatment agreed upon. Risk of contagion is recorded in the referral.
Implementation of supervised treatment
Carrying out of contact tracing
Diagnosis
Chest x-ray
Bacteriological samples: sputum staining and culture for tuberculosis using a total of 3 samples collected on 2 consecutive days
Result of staining is available in a few days, culture takes 4-6 weeks).
Laboratory tests based on gamma interferon production (IGRA = Interferon Gamma Release Assay) are a kind of “tuberculin tests performed in a laboratory”. A positive result does not distinguish active tuberculosis from latent tuberculosis infection, and therefore the diagnosis should be based on Mycobacterium culture and staining. IGRA tests are more specific than tuberculin skin tests. They are used primarily in infection tracing and when considering starting treatment for latent tuberculosis.
Differential diagnosis
Pneumonia Pneumonia (on the other hand, consider tuberculosis if pneumonia responds poorly to treatment)
The drug treatment differs from standard treatment and must be started urgently!
Bones and joints
Pleura
Pericardium
Tuberculosis may be in any organ.
Miliary tuberculosis
A disseminated blood-borne form of tuberculosis
Miliary pulmonary changes may be found in imaging studies
Chest x-ray may be normal at the initial stage. High resolution computed tomography may be diagnostic in such cases.
A negative tuberculin test may be a sign of severe tuberculosis.
Consider miliary tuberculosis in elderly institutionalized patients with prolonged fever and an elevated serum alkaline phosphatase concentration.
In patients with AIDS a mycobacterial infection may have special features. Tuberculosis may be the first manifestation of an HIV infection.
Causes of misdiagnosis
The diagnosis is not considered.
Tuberculosis is treated as an other disease.
The symptoms of tuberculosis are thought to be an exacerbation of an underlying disease.
Infectiousness
Mycobacteria-containing aerosol is most infective (coughing, suction of the airways).
In practice only pulmonary tuberculosis is infectious.
The disease is never transmitted by contaminated objects.
The infectiousness depends on the amount of mycobacteria in the sputum Exposure to Tuberculous Infection. If the bacteria are detected by staining, the risk of transmission exists beyond dispute. In addition, a person who has staining-negative sputum but in whom imaging studies of the lungs show a cavity can be considered infectious. Also the contacts of a staining-negative patient with pulmonary tuberculosis are examined if these are unvaccinated children or live in the same family.
Follow local requirements regarding reporting of the infection to the appropriate authorities.