Leprosy is a chronic granulomatous infectious and disabling disease caused by two mycobacteria, Mycobacterium leprae and Mycobacterium lepromatosis. Acute inflammatory responses, known as leprosy reactions, are significant contributors to disabilities. Three types of leprosy reactions have been identified based on excessive cytokine release (e.g. type 1) or the accumulation of immune complexes in tissues inducing multiorgan damage (e.g. types 2 and 3). The type of leprosy reaction has implications on treatment and management strategies, yet are not well understood by health workers caring for leprosy patients. We attempt to describe the immunologic mechanisms behind the different leprosy reactions and the rationale for tailoring clinical treatment and management to the particular type of leprosy reaction based on the underlying immunologic situation.

Leprosy is is still considered a public health issue and in Colombia 7–10% of new cases are found in children, indicating both active transmission and social inequality. We hypothesized that circulating antibodies against Natural Octyl Disaccharide-Leprosy IDRI Diagnostic (NDO-LID) (a combination of Mycobacterium leprae antigens) could reveal the social and environmental aspects associated with higher frequencies of M. leprae infection among children and adolescents in Colombia. An observational cross-sectional study was conducted involving sampling from 82 children and adolescents (younger than 18 years of age) who had household contact with index leprosy patients diagnosed in the last 5 years. Data were analyzed through bivariate analysis made by applying a Pearson x2 test for qualitative variables, while quantitative variables, depending on their distribution, were analyzed using either a Student’s t-test or Mann-Whitney U test. Multivariate analysis was performed using a multiple regression and binomial logistic approach. A bivariate analysis demonstrated that antibody titers against NDO-LID were significantly greater in children and adolescents with a low socioeconomic status that had: lived in vulnerable areas of the UAChR shared region; eaten armadillo meat; exposure of over 10 years to an index case and; not received BCG immunization. Moreover, a multivariate analysis showed that residing in the UAChR region has a strong association with a greater possibility of M. leprae infection. M. leprae transmission persists among young Colombians, and this is associated with social and environmental conditions. An intensification of efforts to identify new leprosy cases in vulnerable and forgotten populations where M. leprae transmission continues therefore appears necessary.

Leprosy is a chronic infectious disease with a broad spectrum of manifestations. Delays in attaining correct diagnosis permit progressive peripheral nerve damage that can produce irreversible disabilities. Tests detecting antigen-specific antibodies can aid the diagnostic process and potentially detect patients earlier. Reported tests have lacked optimal sensitivity and specificity; however, the need to develop new tests to aid early diagnosis still remains. In this study, we determined the sensitivity, specificity, positive predictive value, and negative predictive value of enzyme-linked immunosorbent assay (ELISA) using natural octyl disaccharide-leprosy IDRI diagnostic (NDO-LID). Serum samples from confirmed multibacillary patients (N = 338) and paucibacillary patients (N = 58) were evaluated and contrasted against samples from individuals without leprosy (100 healthy persons, 36 leishmaniasis or tuberculosis patients). ELISA detecting either antigen-specific IgM, IgG, or the combination of IgG and IgM (with protein A) were conducted. At a sensitivity of 78% among all patients, serum IgM antibodies against the NDO-LID conjugate were detected at a greater level than those recognizing phenolic glycolipid-I antigen (64% overall sensitivity), while providing similar specificity (97% versus 100%, respectively). Given the inclusion of the LID-1 protein within NDO-LID, we also detected conjugate-specific IgG within patient sera at a sensitivity of 81.6%. The use of protein A to simultaneously detect both antigen-specific IgG and IgM isotypes yielded the highest overall sensitivity of 86.3%. Taken together, our data indicate that the detection of both IgG and IgM antibodies against NDO-LID with protein A provided the best overall ability to detect Colombian leprosy patients.

Cutaneous leishmaniasis (CL) is an infectious and neglected disease caused by parasites of the genus Leishmania, which produces a wide spectrum of cutaneous manifestations. CL research has shown that the innate immune activity of cells such as neutrophils, natural killers, macrophages, dendritic cells and the complement system are capable of controlling this infection. However, Leishmania can also modulate the immune activity of these cells to promote its own survival and proliferation at the intracellular level. This review discusses the role of the innate immune response in the control and spread of this infection.

Background: Serological evaluation of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an alternative that allows us to determine the prevalence and dynamics of this infection in populations. The goal of this study was to determine the clinical and sociodemographic dynamics of SARS-CoV-2 infection in a region of the Colombian Caribbean. Methods: Between July and November 2020, a cross-sectional observational study was carried out in Córdoba, located in northeast Colombia in the Caribbean area. Eight municipalities with the largest populations were chosen and 2564 blood samples were taken. A commercial enzyme-linked immunosorbent assay was used with the recombinant protein antigen N of SARS-CoV-2. The people included in the study were asked for sociodemographic and clinical data, which were analysed by statistical methods. Results: A seroprevalence of 40.8% was obtained for SARS-CoV-2 in the Córdoba region. In the bivariate analysis, no differences were observed in seropositivity against SARS-CoV-2 for gender or age range (p>0.05). Higher seropositivity was found in low socio-economic status and symptomatic patients (p<0.0001). A total of 30.7% of the asymptomatic patients were seropositive for SARS-CoV-2, which could be linked to the spread of this infection. In the multivariate analysis, seroconversion was related to poverty and clinical manifestations such as anosmia and ageusia (p<0.05). Conclusions: The high seropositivity in Córdoba is due to widespread SARS-CoV-2 in this population. The relationship between seropositivity and socio-economic status suggests a higher exposure risk to the virus caused by informal economic activities in low-income groups. Clinical manifestations such as anosmia and ageusia could be clinical predictors of infection by the new emergent coronavirus.

Leprosy is a neglected disease caused by Mycobacterium leprae and Mycobacterium lepromatosis, and is related to significant disabilities resulting from the neural damage generated by this mycobacteria. Neuropathic ulcers—lesions that can appear at the plantar and extra-plantar levels—are one such disability, and diagnosis requires an adequate dermatological, neurological and microbiological evaluation. The treatment of these lesions is based on a multidisciplinary approach that includes debridement of the necrotic tissue, controlling infections, reducing pressure areas, optimising blood flow, and nerve decompression. This review aims to describe the clinical features, diagnostic methods and treatment of neuropathic ulcers in leprosy. The diagnostic methods and medical management used in leprosy ulcers are based on those used for diabetic foot. This requires radical change as these diseases are immunologically and physiologically very different.