Validation of a New Duplex Real-Time Polymerase Chain Reaction for Chlamydia trachomatis DNA Detection in Ocular Swab Samples.

Trachoma is the world-leading infectious cause of preventable blindness and is caused by the bacteria Chlamydia trachomatis. In developing countries, diagnosis is usually based on clinical evaluation. Serological-based tests are cheaper than molecular-based ones, but the latter are more sensitive and specific. The present study developed a new duplex qPCR which concomitantly detects the C. trachomatis cryptic plasmid and the human 18S rRNA gene, with an LOD95% for C. trachomatis DNA of 13.04 genome equivalents per reaction. The new qPCR was tested using 50 samples from an endemic area and 12 from a non-endemic area that were previously characterized using direct immunofluorescence assay (DFA) and clinical evaluation. Among the 50 endemic samples, 3 were found to be positive by clinical evaluation (6%), 18 were found to be positive by DFA (36%), and 48 were found to be positive by qPCR (96%). Next, the new duplex qPCR was validated using 50 samples previously characterized by qPCR. Validation was carried out on a benchtop instrument (ABI7500) or on a portable point-of-care instrument (Q3-Plus), showing 95% specificity and 100% sensitivity. The ubiquitous presence of C. trachomatis DNA in samples from the endemic region confirms that constant monitoring is of paramount importance for the effective measurement of the elimination of trachoma. The newly developed duplex qPCR presented in this study, along with its validation in a portable qPCR system, constitutes important tools toward achieving this goal.

Prevalence of trachoma in the non-indigenous Baixo Jaguaribe micro-region, Ceará State, Northeast Brazil.

BACKGROUND: The aim of the current study was to estimate the population prevalence of trachoma in non-indigenous populations in the Baixo Jaguaribe micro-region, in the state of Ceará, northeast region of Brazil, 2021-2022. METHODS: A population-based prevalence survey focusing on detecting cases of trachomatous inflammation-follicular (TF) in children aged 1-9 y and trachomatous trichiasis (TT) 'unknown to the health system' in people aged ≥15 y, was conducted in rural areas of the Baixo Jaguaribe micro-region in the state of Ceará. Indigenous populations will be further researched. RESULTS: There was no detection of cases of TF and TT. In 900 households, 2234 people were examined. In the Baixo Jaguaribe micro-region, females (54.6%; 1219/2234) and the mixed/Pardo-Brazilian ethnicity (68.1%; 1521/2234) predominated. The most commonly reported educational level was elementary and middle school (41.8%; 702/1679). In 56.2% (506/900) of households, there was a source of water within the household. The monthly income range of 50%-100% of the minimum wage predominated in the families of the Baixo Jaguaribe micro-region (43.1%; 388/900). CONCLUSIONS: Although no cases of TF and TT were detected in the Baixo Jaguaribe micro-region in the state of Ceará during the study period, considering the historical endemicity, we emphasise the need for monitoring and sustainability of surveillance actions in areas at risk for trachoma, common contexts for neglected populations.

Genome sequencing of dengue virus serotype 4 in a bat brain sample (Platyrrhinus helleri) from the Brazilian Amazon.

The existence of sylvatic transmission of dengue virus in communities of neotropical bats remains uncertain. In this work we present a near-complete genome of dengue virus serotype 4 obtained from the brain sample of a bat from Platyrrhinus helleri specie collected in the Brazilian Amazon region. The presence of the virus in the brain sample may indicate a possible tropism for the central nervous system in bats, which may justify negative results in previous studies that focused on analysis of other tissues, such as liver and spleen. Besides the duration of dengue virus circulation in the Americas (circa 40 years) may be too short for an implementation of a sylvatic dengue virus cycle. Our findings suggest that continued monitoring is needed to confirm with the neotropical bats could potentially act as a natural reservoir of dengue in the region.

Metagenomic Analysis of Samples from Three Bat Species Collected in the Amazon Rain Forest.

We report here the sequencing of five microbiome samples collected from different bat species in the Amazon rain forest. All contigs matching virus sequences were assigned to members of the Retroviridae family, while the bacterial contigs matched several bacterial species mostly belonging to the Proteobacteria phylum.

Complete Endogenous Retrovirus Genome Sequence from a Brazilian Vampire Bat (Desmodus rotundus).

The strain Desmodus rotundus endogenous retrovirus (DrERV) QR09 was obtained from a bat tissue sample collected from Desmodus rotundus in the Brazilian rain forest. The complete genome was sequenced using the next-generation sequencing strategy. The full-length genome of DrERV QR09 is 8,256 nucleotides in length and showed high similarity with other DrERVs.