By Carol A. Kemper, MD, FACP
Clinical Associate Professor of Medicine, Stanford University, Division of Infectious Diseases, Santa Clara Valley Medical Center
SOURCE: Stuck L, van Haaster AC, Kapata-Chanda P, et al. How “subclinical” is subclinical tuberculosis? An analysis of national prevention survey data from Zambia. Clin Infect Dis 2022;75:842-848.
Many screening tools for identifying cases of pulmonary tuberculosis (TB) focus on the presence of cough for two weeks or longer, along with other possible symptoms. However, many patients present with insidious complaints, such as weight loss or chest pain without cough. A patient recently presented with three weeks of chest pain alone and was treated repeatedly with non-steroidals for a “pulled muscle.” In my experience, the lack of cough, or at least the lack of persistent cough, leads clinicians down the wrong path, and TB is not considered in the differential. Such patients often are referred to as “subclinical TB,” although they still may be infectious.
Stuck et al assessed presenting symptoms in 257 patients with confirmed pulmonary TB in Zambia, all of whom tested positive through sputum cultures or GeneXPERT MTB/RIF testing. The average age was 42.1 years, 56.4% were men, and 14% were HIV-infected (although 49% declined HIV testing). Presenting symptoms of any duration (in decreasing order of frequency) included cough (71.6%), chest pain (65%), weight loss (49%), fever (40.9%), and night sweats (35.4%). Only 12.5% of these patients presented with all five symptoms, and 8.9% reported none.
Of the 257 patients, 40.5% did not report cough for two or more weeks, and 28.4% never coughed. Of the 73 patients with no cough, chest pain and night sweats occurred in six, and chest pain and fever occurred in five. One-third of these patients with “subclinical” TB without cough or cough for less than two weeks experienced symptoms for at least one month, and 9.6% reported symptoms for at least three months.
Therefore, the authors cautioned against using clinical queries that focus on the presence of cough for two or more weeks, which could lead to delays in the diagnosis of nearly half of pulmonary TB cases.
Be careful about relying on clinical queries that focus on the presence of cough for two or more weeks, which could lead to delays in the diagnosis of nearly half of pulmonary tuberculosis cases.
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