The need for culture in tegumentary leishmaniasis diagnosis in Bolivia: A comparative evaluation of four parasitological techniques using two sampling methods.

Leishmaniases are zoonotic diseases caused by protozoa of the genus Leishmania. In Bolivia, leishmaniasis occurs mainly in the cutaneous form (CL) followed by the mucosal or mucocutaneous form (ML or MCL), grouped as tegumentary leishmaniosis (TL), while cases of visceral leishmaniasis (VL) are rare. The cases of TL are routinely diagnosed by parasitological methods: Direct Parasitological Exam (DPE) and axenic culture, the latter being performed only by specialized laboratories. The aim of the present study was to optimize the parasitological diagnosis of TL in Bolivia, using two sampling methods. Samples from 117 patients with suspected TL, obtained by aspiration (n = 121) and scraping (n = 121) of the edge of the lesion were tested by: direct parasitological exam, culture in TSTB medium, and miniculture and microculture in Schneider's medium. A positive laboratory result by any of the four techniques evaluated using either of the two sampling methods was considered the gold standard. Of the 117 suspected patients included, TL was confirmed in 96 (82 %), corresponding 79 of the confirmed cases (82.3 %) to CL and 16 (16.7 %) to ML. Parasitological techniques specificity was 100 % and their analytical sensitivity was greater with scraping samples in TSTB culture (98 %). Scraping samples in TSTB and miniculture correlated well with the reference (Cohen's kappa coefficient=0.88) and showed good reliability (Cronbach's alpha coefficient ≥0.91). Microculture provided positive results earlier than the other culture methods (mean day 4.5). By day 14, 98 % of positive cultures had been detected. Scraping sampling and miniculture were associated with higher culture contamination (6 % and 17 %, respectively). Bacterial contamination predominated, regardless of the sampling and culture method, while filamentous fungi and mixed contamination were more frequently observed in cultures from scraping samples. In conclusion: (i) scraping samples proved more suitable for the diagnosis of TL as they increased analytical sensitivity, are less traumatic for the patient and are safer for laboratory personnel than aspirates; (ii) culture, mainly in TSBT medium, should be used for the diagnosis of TL due to its high sensitivity (doubling the number of cases diagnosed by DPE) and its low cost compared to other culture media.

Hybrid Immunity for COVID-19 in Bolivian Healthcare Workers.

Introduction Vaccination is one of the pillars for the prevention of COVID-19 in healthcare workers (HCWs). The present study aims to determine the effectiveness of vaccination for COVID-19 as well as hybrid immunity in previously infected HCWs in a hospital in a developing country. Methods An observational study was carried out on health personnel with a complete COVID-19 vaccination schedule according to their previous infection status, with a follow-up period of 15 months. Results In this study, 335 subjects were enrolled, of which 32.8% had a previous infection with COVID-19. The safety of vaccines was determined by estimating the presence of adverse effects of vaccination and immunization (AEVI), with the first and second doses showing an incidence of 8.2% and 9.5% respectively, during the second and third waves. Around 5.7% of immunized personnel were sick and 8.4% in the fourth wave; the serum value of neutralizing antibodies was normal at 60.2% with no differences between vaccines (p=0.164). However, in personnel with hybrid immunity, there were normal levels of antibodies in 81.8% of cases (p= 0.023), fewer days of medical leave (6.4 days (standard deviation=1.4) (p=0.067)), higher immunoglobin values ​​(p=0.011) and an insignificantly (p=0.248) lower rate of COVID-19 presentation. Conclusion Vaccination, when applied to people who previously acquired natural immunity, generates a hybrid immunity that is robust, and could have a longer duration, as well as greater efficacy for new COVID-19 variants of concern.