Better understanding extrapulmonary tuberculosis: A scoping review of public health impact in Pakistan, Afghanistan, India, and Bangladesh

Background and Aims

South Asian countries, including Pakistan, Afghanistan, India, and Bangladesh, have a high prevalence of pulmonary and extra-pulmonary tuberculosis (EPTB). This prevalence is influenced by various risk factors such as ethnicity, nutrition, socioeconomic disparities, high out-of-pocket healthcare expenses, and specific Mycobacterium Tuberculosis (TB) lineages. The COVID-19 pandemic has likely hindered access to healthcare and led to under-reporting of EPTB cases nationally and internationally. This rapid review aimed to summarize the literature on the prevalence and disease outcomes of EPTB in the mentioned countries, compare the situations across countries, and provide recommendations for future action.

Methods

The review utilized PubMed and Google Scholar databases to search for literature on EPTB in South Asian countries. The search string included keywords related to different forms of EPTB and the countries of interest while excluding pulmonary tuberculosis.

Results

The results showed that both TB, including drug-resistant TB, and EPTB are prevalent and burdensome in South Asia. In Pakistan, pleural TB was the most commonly reported form of EPTB, followed by lymph node TB, abdominal TB, osteoarticular TB, Central Nervous System TB, and miliary TB. In India, lymph node TB(LNTB) was more common among EPTB cases. Bangladesh reported a high prevalence of EPTB involving lymph node, pleura, and abdomen, while Afghanistan had a higher prevalence of forms such as LNTB and tuberculous meningitis.

Conclusion

In conclusion, the prevalence of EPTB in Pakistan, Afghanistan, India, and Bangladesh is alarmingly high and negatively impacts population health. Effective measures are needed for treatment and management of this condition, along with addressing current and future challenges. Strengthening the evidence base through surveillance and research is crucial to understand the patterns and significant factors related to EPTB, requiring investment in these areas.

Application of Mycobacterium tuberculosis RNA for the Rapid Diagnosis of Lymph Node Tuberculosis Using Different Specimens

Purpose

To evaluate the accuracy of Mycobacterium tuberculosis (MTB)-RNA in the rapid diagnosis of lymph node tuberculosis (LNTB). Moreover, the difference in the diagnostic accuracy of MTB-RNA using different specimens was determined.

Methods

We included patients with suspected LNTB who met the inclusion criteria and retrospectively analyzed their clinical data. The sensitivity, specificity, positive-predictive value (PPV), negative-predictive value (NPV), and area under the curve (AUC) of MTB-RNA and culture were calculated and its diagnostic accuracy for LNTB was evaluated in comparison with the final clinical diagnosis.

Results

Overall, 285 patients were included in the study. The overall sensitivity, specificity, PPV, NPV, and AUC of MTB-RNA were 40.6%, 100.0%, 100.0%, 17.0%, and 0.70, respectively. These values were 30.8%, 100.0%, 100.0%, 16.0%, and 0.65, respectively, for tissue specimens; 34.2%, 100.0%, 100.0%, 24.6%, and 0.67, respectively, for puncture specimens; and 57.14%, 100.0%, 100.0%, 5.3%, and 0.79, respectively, for pus specimens. These values of culture were 24.4%, 100.0%, 100.0%, 13.9%, and 0.62, respectively, for all specimens; 17.6%, 100.0%, 100.0%, 13.8%, and 0.59, respectively, for tissue specimens; 25.3%, 100.0%, 100.0%, 22.4%, and 0.63, respectively, for puncture specimens; and 31.0%, 100.0%, 100.0%, 3.3%, and 0.65, respectively, for pus specimens.

Conclusion

The diagnostic efficacy of MTB-RNA for the rapid diagnosis of LNTB was moderate, but its sensitivity was low. The lymph node pus specimens were the most sensitive for MTB-RNA testing, followed by puncture specimens; tissues were the least sensitive. Pus specimens should be preferably obtained in case only this test is to be used for diagnosis.

In vivo Whole-Cell Recordings Combined with Electron Microscopy Reveal Unexpected Morphological and Physiological Properties in the Lateral Nucleus of the Trapezoid Body in the Auditory Brainstem

The lateral nucleus of the trapezoid body (LNTB) is a prominent nucleus in the superior olivary complex in mammals including humans. Its physiology in vivo is poorly understood due to a paucity of recordings. It is thought to provide a glycinergic projection to the medial superior olive (MSO) with an important role in binaural processing and sound localization. We combined in vivo patch clamp recordings with labeling of individual neurons in the Mongolian gerbil. Labeling of the recorded neurons allowed us to relate physiological properties to anatomy at the light and electron microscopic level. We identified a population of quite dorsally located neurons with surprisingly large dendritic trees on which most of the synaptic input impinges. In most neurons, one or more of these dendrites run through and are then medial to the MSO. These neurons were often binaural and could even show sensitivity to interaural time differences (ITDs) of stimulus fine structure or envelope. Moreover, a subpopulation showed enhanced phase-locking to tones delivered in the tuning curve tail. We propose that these neurons constitute the gerbil main LNTB (mLNTB). In contrast, a smaller sample of neurons was identified that was located more ventrally and that we designate to be in posteroventral LNTB (pvLNTB). These cells receive large somatic excitatory terminals from globular bushy cells. We also identified previously undescribed synaptic inputs from the lateral superior olive. pvLNTB neurons are usually monaural, display a primary-like-with-notch response to ipsilateral short tones at CF and can phase-lock to low frequency tones. We conclude that mLNTB contains a population of neurons with extended dendritic trees where most of the synaptic input is found, that can show enhanced phase-locking and sensitivity to ITD. pvLNTB cells, presumed to provide glycinergic input to the MSO, get large somatic globular bushy synaptic inputs and are typically monaural with short tone responses similar to their primary input from the cochlear nucleus.