Viral hepatitis and Treponema pallidum prevalence in persons who underwent premarital blood tests in Argentina

Seroprevalence of hepatitis A virus among people born before and after implementation of universal vaccination in Argentina

BACKGROUND

Until 2005, when a single dose of vaccine was implemented in one-year-old children, the Hepatitis A virus (HAV) was responsible for approximately 90% of acute hepatitis cases in the paediatric population in Argentina. However, despite vaccination success, sporadic outbreaks of HAV still occur among adults. This study aimed to assess the seroepidemiology of HAV in Argentina, analysing IgG and IgM antibodies against HAV in a large population, both vaccinated and unvaccinated.

METHODS

The study included 16,982 patients attending a hospital from 2001 to 2023. The cohort was divided into two groups: 16,638 individuals who were not reached by the vaccination program implemented in 2005 and 344 children who were covered by the universal vaccination.

RESULTS

Anti-HAV IgG was detected in 56.7% of cases. The rate was significantly higher in individuals born after 2005 (77.7%) compared to those born before (56.3%), p < 0.001. The age groups 19-40 and 41-60 years showed the anti-HAV IgG lowest rates. On the other hand, 100/3956 cases (2.5%) with suspected acute hepatitis were positive for Anti-HAVIgM. Notably, none of these were born after the mandatory vaccine rollout.

CONCLUSIONS

The study of this large cohort contributes to the understanding of the seroepidemiology of HAV. Although the implementation of the vaccine achieved its main goal, the age segment between 19 and 60 years does not reach the estimated threshold to achieve herd immunity. These findings reveal the importance of targeting vaccination campaigns, provide essential insights for public health planning, and guide future immunisation strategies against HAV in Argentina.

Hepatitis A virus monitoring in wastewater: A complementary tool to clinical surveillance

Monitoring wastewater is an effective tool for tracking information on trends of enteric viral dissemination. This study aimed to perform molecular detection and genetic characterization of HAV in wastewater and to correlate the results with those obtained from clinical surveillance. Wastewater samples (n=811) of the second most populous city in Argentina were collected from the main wastewater treatment plant (BG-WWTP, n=261), and at 7 local neighborhood collector sewers (LNCS, n=550) during 2017-2022. Clinical samples of acute hepatitis A cases (HA, n=54) were also analyzed. HAV molecular detection was performed by real time RT-PCR, and genetic characterization by RT-Nested PCR, sequencing and phylogenetic analysis. RNA-HAV was detected in sewage samples throughout the entire period studied, and detection frequencies varied according to the location and year (2.9% - 56.5%). In BG-WWTP, 23% of the samples were RNA-HAV+. The highest detection rates were in 2017 (30.0%), 2018 (41.7%) and 2022 (56.5%), which coincides with the highest number of HA cases reported. Twenty-eight (28) sequences were obtained (from clinical and sewage samples), and all were genotype IA. Two monophyletic clusters were identified: one that grouped clinical and wastewater samples from 2017-2018, and another with specimens from 2022, evidencing that environmental surveillance might constitute a replica of viral circulation in the population. These findings evidence that WBE, in a centralized and decentralized sewage monitoring, might be an effective strategy to track HAV circulation trends over time, contributing to the knowledge of HAV in the new post-vaccination epidemiological scenarios in Argentina and in Latin America.

Acceptability of dual HIV/syphilis rapid test in community- and home-based testing strategy among transgender women in Buenos Aires, Argentina

BACKGROUND

Little is known of acceptability and feasibility of dual HIV and syphilis rapid tests in community- and home-based provider-initiated strategies among transgender women (TGW), in Latin America. Objectives were (1) to assess the acceptability of this strategy and, (2) to determine the percentage of positive results of HIV and syphilis, analyze the correlates of HIV or syphilis positive results, and measure the rates of effective referral and treatment completion among TGW.

METHODS

A multidisciplinary team tested 89 TGW in Buenos Aires. An acceptability survey was administered after the HIV/syphilis Duo test was used. All confirmed cases were referred for treatment initiation.

RESULTS

We found high levels of acceptability (98.8%) of this strategy among TGW. However, only 60.7% preferred simultaneous HIV and syphilis diagnosis test. Moreover, we found 9% of positive results of HIV, 51.7% of syphilis, and 3.4% of positive results for both infections. Only not being tested before was associated with an HIV positive result, and only low level of education was associated with a positive syphilis result. Among 8 TGW who tested positive for HIV, 37.5% (n = 3) started antiretroviral therapy. Of 46 who tested positive for syphilis, only 73.9% (n = 34) were effectively referred and from 23 who started treatment, only 39.1% completed it.

CONCLUSIONS

Community- and home-based dual HIV and syphilis rapid test is a feasible and highly acceptable approach for this hard-to-reach population. Implementing similar strategies could improve screening uptake and accessibility. However, these results highlight the need to improve strategies for treatment uptake, in order to reduce morbidity and risk of onward transmission.

Syphilis and HIV infection in indigenous Mbya Guarani communities of Puerto Iguazu (Argentina): diagnosis, contact tracking, and follow-up

The aim of study was to assess the prevalence of Treponema pallidum and HIV infection in Amerindian people (Mbya Guarani) over the age of 11 in Puerto Iguazu (Argentina) and to describe the contact tracking of cases. The method was a cross-sectional study in the Mbya Guarani people living in three villages of Puerto Iguazu (community A, pop. 1,146; community B, pop. 369; and community C, pop. 149). Participants were randomly invited to participate in the survey and in blood testing. Of the 551 participants, 48 were infected by T. pallidum (8.71%; 95% confidence interval [CI] 7.38-10.04). The infection prevalence decreased with age, standing at 9.66% in the 11-19 age group, 8.42% in 20-39 age group and 4.54% in people aged 40 and older. We tracked 130 contacts for the 48 T. pallidum cases; 39/40 (97.5%) sexual contacts tested positive for syphilis. Among the 90 children born to infected mothers, 76 aged 18 months or older tested negative, while 8/14 younger children were still at risk for congenital syphilis. There were four cases of HIV infection (0.72%, 95% CI 0.31-1.13). Prevalence of T. pallidum infection and HIV infection are relevant in this indigenous community of Argentina, representing a public health concern.