Masturbation is a common sexual practice in men, and saliva is often used as a lubricant during masturbation by men who have sex with men. However, the role of saliva use during masturbation in the transmission of chlamydia is still unclear. We developed population-level, susceptible-infected-susceptible compartmental models to explore the role of saliva use during masturbation on the transmission of chlamydia at multiple anatomical sites. In this study, we simulated both solo masturbation and mutual masturbation. Our baseline model did not include masturbation but included transmission routes (anal sex, oral-penile sex, rimming, kissing and sequential sexual practices) we have previously validated (model 1). We added masturbation to model 1 to develop the second model (model 2). We calibrated the model to five clinical datasets separately to assess the effects of masturbation on the prevalence of site-specific infection. The inclusion of masturbation (model 2) significantly worsened the ability of the models to replicate the prevalence of C. trachomatis. Using model 2 and the five data sets, we estimated that saliva use during masturbation was responsible for between 3.9% [95% confidence interval (CI) 2.0–6.8] and 6.2% (95% CI 3.8–10.5) of incident chlamydia cases at all sites. Our models suggest that saliva use during masturbation is unlikely to play a major role in chlamydia transmission between men, and even if it does have a role, about one in seven cases of urethral chlamydia might arise from masturbation.

The anatomical and biochemical basis of resistance of Vigna vexillata (Benth) (Ace. TVNu 72) to Monica testulalis were investigated. An uncharacteristic network of fibrous structures was observed on the petal surface of TVNu 72 but not on those of the susceptible control, IT82D-716. Stems of TVNu 72 and IT82D-716 have thick and closely packed collenchyma cells. Both varieties have been identified as possessing resistance to stem feeding; however, IT82D-716 is susceptible to flower and pod damage. The distance between pod wall epicarp and mesocarp was significantly (P ≺ 0.05) smaller in IT82D-716, but cell and tissue arrangement were similar for both varieties.

Total sugar content in the pod wall and seed of TVNu 72 was higher (P ≺ 0.05) than in IT82D-716. Phenol content was lower (P ≺ 0.05) in the pod wall of TVNu 72 but the reverse was true for fresh and dry seeds. This suggests that neither phenol nor total sugar are involved in the resistance of TVNu 72 to M. testulalis. However, it seems that thick and compact collenchyma cells in the stems and Fibrous tissues on the petal surface contribute to the resistance in TVNu 72. The results are discussed in line with previous reports which indicate that trichomes are the principal factors in the resistance of TVNu 72 to M. testulalis.