Introduction Prisoners are at a higher risk of communicable diseases (such as HIV and hepatitis) than the general population. Therefore, medical screening is crucial for early diagnosis, treatment, identifying those at higher risk of infection, and prevention of infection spread. Objective The main objective of this study was to analyze the factors associated with hepatitis B and C seropositivity in the prison population in Montenegro in two consecutive study years. Method Prisoners of Prison for Short and Long prison terms in Spuž, Montenegro, were included in two cross-sectional studies during 2012 and 2021. Data on socio-demographic factors, risky behavior, and preventive measures related to blood-borne viruses were collected. The data were statistically processed by statistical testing of differences and applying regression models in SPSS Windows, version 19. Results A total of 506 prisoners (2012–298; 2021–208) were included in this study. One fifth of prisoners were seropositive for viral hepatitis B (2012–0.7%; 2021–3.4%) or C (2012–21.8%; 2021-20.7%) or both (2012–0.33%; 2021–0.0%). Factors associated with viral hepatitis B and C seropositivity in both years were shorter prison terms served and injection drug use. Additionally, factors associated with prisoners seropositivity in 2012 were ever drug use and lack of free hygiene kits in prison, and in 2021 were condom use with a permanent partner, non-condom use with non-permanent partner, and availability of free syringes and needles distribution. Conclusion and recommendation Prevalent risky behaviors and the lack of harm reduction interventions are more common among seropositive prisoners. Establishing a prison hospital, improving the surveillance system, introducing new or improving old harm reduction interventions is imperative.

Developmental abnormalities in elasmobranchs (sharks and rays) are rarely documented, with reported cases primarily involving fin or cranial deformities. Monozygotic twinning, the formation of identical twins from a single zygote, is particularly rare in these species and has been observed overwhelmingly in viviparous elasmobranchs. Here, we document a rare case of monozygotic twinning in an oviparous shark, the Small-spotted Catshark Scyliorhinus canicula (Linneaus, 1758). This case was characterized by two embryos connected to a single yolk sac via separate yolk stalks within the egg capsule. The embryos exhibited normal development until mortality at developmental Stage 31 (Ballard et al., 1993) or stage 4 (Musa et al., 2018), likely due to stressors such as oxidative stress and allostatic overload, resulting from shared resources within the capsule. This is the first confirmed instance of mortality in monozygotic elasmobranch twins, highlighting the plausible challenges of polyembryony in oviparous elasmobranchs. These findings underscore the importance of understanding reproductive abnormalities and their implications for fecundity, particularly in light of ongoing anthropogenic pressures that threaten elasmobranch populations globally.