DIAGNOSIS OF TB AND HIV
Among 33.2 million people living with HIV about one-third is also infected with tuberculosis (TB). According to the World Health Organization (WHO), about a quarter (28%) of all HIV deaths are associated with TB.
In response, WHO has developed a policy on the provision of TB/HIV integrated services aiming to reduce the TB burden among people living with HIV, as well as the HIV burden among TB patients.
The policy of joint action in the field of TB/HIV envisages 12 steps that must be taken within the framework of National Programs for TB and HIV in order to respond to TB/HIV co-infection.
The key areas are as follows:
- Cooperation and coordination in terms of TB/HIV activities on the national level;
- TB prevention among HIV patients;
- HIV prevention among TB patients.
Practical approaches to TB burden reduction among HIV patients are outlined in the Three I’s strategy (Intensified TB case finding, Isoniazid preventive therapy and Infection control). Unfortunately, this approach is not widely spread in our country.
The main method of Intensified case finding is surveying HIV+ patients with TB symptoms during their every visit to the AIDS center. This intervention does not require investments and allows suspecting TB at an early stage and timely redirecting the patient for further TB diagnosis.
Isoniazid preventive therapy (IPT) has proven its effectiveness in many countries. Due to the introduction of isoniazid preventive therapy, many countries have largely reduced the number of new TB cases among HIV+ patients. The method is simple and cheap: the cost of the IPT course per month is less than 10 UAH but it saves lives and health.
Infection control is a set of measures to reduce the spread of infection within hospital and other public places.
The basis for infection control in this case should be the administrative control measures. It is appropriate for HIV-related NGOs to implement these approaches to prevent infection of both clients and NGO staff.
HIV burden reduction among TB patients is based on the provision of access to counseling and testing for HIV, as well as HIV prevention measures for TB patients.
Quality counseling allows the discussion on the possible factors of risk-taking behavior following the prevention plan development. With the results of HIV testing the doctor is able to develop more appropriate and effective treatment scheme for the patient. Upon TB curing a patient may continue to monitor and treat HIV infection.
Important steps to reduce deaths from TB/HIV are to ensure access to cotrimoxazole preventing therapy for patients with active TB and timely initiation of antiretroviral therapy (ART) for all TB patients.
Cotrimoxazole (trimethoprim/sulfamethoxazole) have long been used for the prevention of Pneumocystis pneumonia among HIV positive people. According to current approaches, all TB/HIV patients during TB treatment should receive this preventive therapy regardless of the immunosuppression level.
Over the last few years the approaches to initiate ART for TB/HIV patients have changed drastically. ART prescription within first 2-8 weeks of TB treatment has proven to significantly increase chances for recovery.
TB/HIV case management is impossible without active cooperation between TB and AIDS services, as well as a special focus on the provision of controlled treatment and development of adherence to ART.
Features of the TB development in HIV infected
Clinical TB signs among HIV infected patients depend on the degree of immunosuppression.
Patients with 1-2 clinical stage (low-symptom stage, with minimal suppression of immunity) TB develops in the usual way and presents no particular difficulties for the diagnosis.
However, with the development of immunodeficiency the clinical picture of TB starts to vary. This occurs as a consequence of the reduced immunity response when the typical tuberculous granulomas are not generated, resulting in easy TB spread to other organs and systems. Therefore, primary and generalized forms of extrapulmonary tuberculosis appear in HIV+ patients.
The bacteria emission is observed less among HIV+ patients, therefore more sensitive diagnostic methods are needed to identify the causative agent.
Detection and diagnosis of TB among people living with HIV
For the early TB detection among HIV+ people WHO recommends screening by surveying the patient during each referral for medical help.
Standard questionnaire includes points about a patient's symptoms that are characteristic of TB (night sweats, fever, lasting cough). If the patient marks the presence of such symptoms, he/she should be referred to examination to prevent TB.
The algorithm of TB diagnosis among HIV positive patients include:
1. Bacterioscopic and bacteriological tests;
2. Molecular genetic tests.
Given the fact that HIV positive patients are "small" bacteria emitters, the most effective diagnosis methods is of molecular genetic type. According to WHO recommendations, the method should be applied without prior microscopy providing faster and cheaper TB diagnosis for HIV positive patients. Moreover, it allows identification of resistance to Rifampicin in the first day. The materials for TB diagnosis are both sputum and punctate or biopsy of the lymph nodes (or other organs) in case of extrapulmonary TB suspicion.