Characterising persons diagnosed with HIV as either recent or long-term using a cross-sectional analysis of recent infection surveillance data collected in Malawi from September 2019 to March 2020

Membrane computing simulation of sexually transmitted bacterial infections in hotspots of individuals with various risk behaviors

The epidemiology of sexually transmitted infections (STIs) is complex due to the coexistence of various pathogens, the variety of transmission modes derived from sexual orientations and behaviors at different ages and genders, and sexual contact hotspots resulting in network transmission. There is also a growing proportion of recreational drug users engaged in high-risk sexual activities, as well as pharmacological self-protection routines fostering non-condom practices. The frequency of asymptomatic patients makes it difficult to develop a comprehensive approach to STI epidemiology. Modeling approaches are required to deal with such complexity. Membrane computing is a natural computing methodology for the virtual reproduction of epidemics under the influence of deterministic and stochastic events with an unprecedented level of granularity. The application of the LOIMOS program to STI epidemiology illustrates the possibility of using it to shape appropriate interventions. Under the conditions of our basic landscape, including sexual hotspots of individuals with various risk behaviors, an increase in condom use reduces STIs in a larger proportion of heterosexuals than in same-gender sexual contacts and is much more efficient for reducing Neisseria gonorrhoeae than Chlamydia and lymphogranuloma venereum infections. Amelioration from diagnostic STI screening could be instrumental in reducing N. gonorrhoeae infections, particularly in men having sex with men (MSM), and Chlamydia trachomatis infections in the heterosexual population; however, screening was less effective in decreasing lymphogranuloma venereum infections in MSM. The influence of STI epidemiology of sexual contacts between different age groups (<35 and ≥35 years) and in bisexual populations was also submitted for simulation.IMPORTANCEThe epidemiology of sexually transmitted infections (STIs) is complex and significantly influences sexual and reproductive health worldwide. Gender, age, sexual orientation, sexual behavior (including recreational drug use and physical and pharmacological protection practices), the structure of sexual contact networks, and the limited application or efficiency of diagnostic screening procedures create variable landscapes in different countries. Modeling techniques are required to deal with such complexity. We propose the use of a simulation technology based on membrane computing, mimicking in silico STI epidemics under various local conditions with an unprecedented level of detail. This approach allows us to evaluate the relative weight of the various epidemic drivers in various populations at risk and the possible outcomes of interventions in particular epidemiological landscapes.

HIV Recent Infection and Past HIV Testing History Among Newly HIV-Diagnosed 15-24-Year-Olds in Malawi: An Analysis of 2019-2022 HIV Recent Infection Surveillance Data

Awareness of HIV status in Malawi is 88.3% and lowest among 15-24-year-olds (76.2%). There is a need to understand HIV testing history and transmission in this age group. We analyzed pooled HIV surveillance data to describe testing history and HIV recent infection among 8,389 HIV-positive 15-24-year-olds from 251 sites in Malawi between 2019 and 2022. Most HIV-positive 15-24-year-olds were female; aged 23-24 years; rural residents; and diagnosed at voluntary counseling and testing. No prior HIV testing was reported in 43.5% and 32.9% of 15-19-year-olds and males, respectively. Overall, 4.9% of HIV-positive diagnoses were classified as recent HIV infections, with the highest proportions among breastfeeding women (8.2%); persons tested at sexually transmitted infection clinics (9.0%); persons with a prior negative test within 6 months (13.0%); and 17-18-year-olds (7.3%). Tailored and innovative HIV prevention and testing strategies for young adolescents, young males, and pregnant and breastfeeding women are needed for HIV epidemic control.