Occult hepatitis B infection (OBI) is characterized by the presence of low levels of hepatitis B virus (HBV) DNA and undetectable HBsAg in the blood. The prevalence of OBI in blood donors in Asia ranges from 0.013% (China) to 10.9% (Laos), with no data available from Vietnam so far. We aimed to investigate the prevalence of OBI among Vietnamese blood donors. A total of 623 (114 women and 509 men) HBsAg-negative blood donors were screened for anti-HBc and anti-HBs by ELISA assays. In addition, DNA from sera was isolated and nested PCR was performed for the HBV surface gene (S); a fragment of the S gene was then sequenced in positive samples. The results revealed that 39% (n = 242) of blood donors were positive for anti-HBc, and 70% (n = 434) were positive for anti-HBs, with 36% (n = 223) being positive for both anti-HBc and anti-HBs. In addition, 3% of blood donors (n = 19) were positive for anti-HBc only, and 34% (n = 211) had only anti-HBs as serological marker. A total of 27% (n = 170) were seronegative for any marker. Two of the blood donors (0.3%) were OBI-positive and sequencing revealed that HBV sequences belonged to HBV genotype B, which is the predominant genotype in Vietnam.

The prevalence of hepatitis E virus (HEV) in the Vietnamese population remains underestimated. The aim of the present study was to investigate the seroprevalence of HEV IgG/IgM antibodies and the presence of HEV RNA in blood donors as a part of epidemiological surveillance for transfusion-transmitted viruses. Serum samples from blood donors (n = 553) were analysed for markers of past (anti-HEV IgG) and recent/ongoing (anti-HEV IgM) HEV infections. In addition, all serum samples were subsequently tested for HEV RNA positivity. The overall prevalence of anti-HEV IgG was 26.8% (n = 148/553), while the seroprevalence of anti-HEV IgM was 0.5% (n = 3/553). Anti-HEV IgG seroprevalence in male and female donors was similar (27.1% and 25.5%, respectively). A higher risk of hepatitis E exposure was observed with increasing age. None of the blood donors were HEV RNA positive, and there was no evidence of HEV viraemia. Although the absence of HEV viraemia in blood donors from Northern Vietnam is encouraging, further epidemiological surveillance in other geographical regions is warranted to rule out transfusion-transmitted HEV.

Trichomoniasis, the most common non-viral sexually transmitted infection worldwide, is caused by the protozoon Trichomonas vaginalis. The 5- nitroimidazole drugs, of which metronidazole is the most prescribed, are the only effective drugs to treat trichomoniasis. Resistance against metronidazole is increasingly reported among T. vaginalis isolates. T. vaginalis can establish an endosymbiosis with two Mycoplasma species, Mycoplasma hominis and Candidatus Mycoplasma girerdii, whose presence has been demonstrated to influence several aspects of the protozoan pathobiology. The role of M. hominis in T. vaginalis resistance to metronidazole is controversial, while the influence of Ca. M. girerdii has never been investigated. In this work, we investigate the possible correlation between the presence of Ca. M. girerdii and/or M. hominis and the in vitro drug susceptibility in a large group of T. vaginalis isolated in Italy and in Vietnam. We also evaluated, via RNA-seq analysis, the expression of protozoan genes involved in metronidazole resistance in a set of syngenic T. vaginalis strains, differing only for the presence/absence of the two Mycoplasmas. Our results show that the presence of M. hominis significantly increases the sensitivity to metronidazole in T. vaginalis and affects gene expression. On the contrary, the symbiosis with Candidatus Mycoplasma girerdii seems to have no effect on metronidazole resistance in T. vaginalis.

Background: Hepatitis E virus (HEV) is a significant cause of acute viral hepatitis, particularly in regions with poor sanitation. Co-infection with hepatitis B virus (HBV) is common in high-risk populations, such as individuals with chronic liver disease, but data on HEV prevalence in patients living with HBV in Southeast Asia are limited. This study investigates HEV seroprevalence among patients with HBV and those with hepatitis of unknown etiology (HUE) in central Vietnam Method: Blood samples from 587 patients with HBV and 158 individuals with HUE were collected and analyzed for anti-HEV immunoglobulin G (IgG) and immunoglobulin M antibodies by enzyme-linked immunosorbent assay. HEV RNA was detected using reverse transcriptase-polymerase chain reaction, and HBV viral load was quantified via real-time polymerase chain reaction. Results: The overall anti-HEV IgG seroprevalence was 26% in patients with HBV and 36% in those with HUE. Although patients with liver cirrhosis and hepatocellular carcinoma exhibited higher rates of anti-HEV IgG seropositivity, these differences were not statistically significant. Among patients with HBV, the seroprevalence was highest in those with liver cirrhosis and hepatocellular carcinoma (46%), whereas the lowest (24%) was found in patients with symptomatic chronic hepatitis B. Only 1 (0.1%) tested positive for anti-HEV immunoglobulin M, and no HEV RNA positivity was detected. Furthermore, biochemical laboratory parameters in patients with liver diseases were not found to be associated with anti-HEV seropositivity. Conclusions: Anti-HEV IgG seroprevalence was relatively high among patients with chronic liver disease, including those with HBV. However, no association was observed between HEV exposure and liver disease progression. HEV is not a common cause of hepatitis in Central Vietnam.