The following is a summary of “Characterizing the Spectrum of Latent Mycobacterium Tuberculosis in the Cynomolgus Macaque Model: Clinical, Immunologic, and Imaging Features of Evolution,” published in the February 2023 issue of Infectious Diseases by Medrano, et al.

Although the results of Mycobacterium TB infection have traditionally been categorized as either active tuberculosis or latent infection, a range of outcomes was recognized. The clinical, microbiological, and radiographic patterns linked to the emergence of latent M. tuberculosis infection were characterized using a nonhuman primate model replicating human infection. 

Four distinct patterns were found. First, the erythrocyte sedimentation rate (ESR) was normal in “controllers,” who did not have any M. tuberculosis growth in their bronchoalveolar lavage or gastric aspirate (BAL/GA). Second, although there was no clinical disease, “early subclinicals” displayed transient ESR elevation and/or M. tuberculosis growth on BAL/GA for 60 days postinfection, “mid subclinicals” were positive for 90 days, and “late subclinicals” occasionally tested positive. Third, Granuloma formation, the metabolic activity of the lung and lymph nodes, the bacterial burden in the lung and lymph nodes, gross pathology, and extrapulmonary illness all showed variation.

Like human M. tuberculosis infection, it demonstrated the variety involved in establishing latent infection, emphasizing the necessity of comprehending the clinical spectrum and risk factors connected to severe disease.

Reference: academic.oup.com/jid/article-abstract/227/4/592/6972364?redirectedFrom=fulltext