Concealed for a Long Time on the Marches of Empires: Hepatitis B Virus Genotype I

Genotype I, the penultimate HBV genotype to date, was granted the status of a bona fide genotype only in the XXIst century after some hesitations. The reason for these hesitations was that genotype I is a complex recombinant virus formed with segments from three original genotypes, A, C, and G. It was estimated that genotype I is responsible for only an infinitesimal fraction (<1.0%) of the chronic HBV infection burden worldwide. Furthermore, most probably due to its recent discovery and rarity, the natural history of infection with genotype I is poorly known in comparison with those of genotypes B or C that predominate in their area of circulation. Overall, genotype I is a minor genotype infecting ethnic minorities. It is endemic to the Southeast Asian Massif or Eastern Zomia, a vast mountainous or hilly region of 2.5 million km2 spreading from Eastern India to China, inhabited by a little more than 100 million persons belonging primarily to ethnic minorities speaking various types of languages (Tibeto-Burman, Austroasiatic, and Tai-Kadai) who managed to escape the authority of central states during historical times. Genotype I consists of two subtypes: I1, present in China, Laos, Thailand, and Vietnam; and I2, encountered in India, Laos, and Vietnam.

Estimating the burden of hepatitis B virus infection in Laos between 2020 and 2021: A cross-sectional seroprevalence survey

BACKGROUND

Laos is considered highly endemic for persistent infection with hepatitis B virus (HBV). To eliminate this burden, it has gradually implemented universal anti-hepatitis B immunisation of newborns over the past two decades.

METHODS

Using VIKIA® HBsAg, a rapid test for the qualitative detection of the HBV surface antigen, we conducted between Sep 1st, 2020 and Aug 31st, 2021 the largest prospective prevalence survey ever in Laos. This survey included blood donors (BD, n = 42,277), patients attending care in capital and provincial hospitals (n = 37,347) including attending mothers (n = 20,548), HIV-infected patients (n = 7439, recruited from 2009 to 2020), students from the Health Sciences University (n = 609), and outpatients (n = 350) coming for diagnosis at the Center Infectiology Lao-Christophe Mérieux in Vientiane. In total, 88,022 persons were tested, representing approximately 1.22% of the national population. To reach a reasonable estimate of HBsAg prevalence in Laos, we segmented the population according to three variables, age (≤20 years as a cut-off), sex, and geographical origin. BD values were used to estimate HBsAg prevalence in patients aged <20 while hospital survey prevalence was used to estimate the prevalence in those aged older than 20 years.

FINDINGS

We observed an HBsAg seroprevalence ranging from 2.6% in blood donors to 8.0% in HIV-infected patients. In BD, men were significantly more at risk to be carriers than women (RR = 1.2, P = 0.00063). For BD, attending mothers, or HIV-infected patients, HBsAg was significantly more prevalent in northern Laos (5.1-8.4%) than in central (2.0-8.1%) or southern parts of the country (2.2-6.9%), thereby delineating a North-to-South gradient.

INTERPRETATION

We considered that HBsAg prevalence probably ranges between 5.0% and 6.0% of the total population. Thus, we consider that Laos may no longer be highly endemic for chronic HBV infection but rather a country with intermediate endemicity.

FUNDING

The funding sources were the Agence Universitaire de la Francophonie, the French Government, the French Institute for Sustainable Development (IRD), and European Union's Horizon 2020 Marie Sklodowska-Curie Actions (MSCA) - Research and Innovation Staff Exchange - (RISE) under grant agreement N° 823935.

Hepatitis C in Laos: A 7-Year Retrospective Study on 1765 Patients

Hepatitis C virus (HCV) is a global health concern, notably in Southeast Asia, and in Laos the presentation of the HCV-induced liver disease is poorly known. Our objective was thus to describe a comprehensive HCV infection pattern in order to guide national health policies. A study on a group of 1765 patients formerly diagnosed by rapid test in health centres was conducted at the Centre of Infectiology Lao Christophe Merieux in Vientiane. The demographic information of patients, their infection status (viral load: VL), liver function (aminotransferases) and treatments were analysed. Results showed that gender distribution of infected people was balanced; with median ages of 53.8 for men and 51.6 years for women (13-86 years). The majority of patients (72%) were confirmed positive (VL > 50 IU/mL) and 28% of them had high VL (> 6log₁₀). About 23% of patients had level of aminotransferases indicative of liver damage (> 40 IU/mL); but less than 20% of patients received treatment. Patients rarely received a second sampling or medical imaging. The survey also showed that cycloferon, pegylated interferon and ribavirin were the drugs prescribed preferentially by the medical staff, without following any international recommendations schemes. In conclusion, we recommend that a population screening policy and better management of patients should be urgently implemented in the country, respecting official guidelines. However, the cost of biological analysis and treatment are significant barriers that must be removed. Public health resolutions should be immediately enforced in the perspective of meeting the WHO HCV elimination deadline by 2030.