Incidence of hepatitis B virus infection among an Italian military population: evidence of low infection spread

A Historical Review of Military Medical Strategies for Fighting Infectious Diseases: From Battlefields to Global Health

The environmental conditions generated by war and characterized by poverty, undernutrition, stress, difficult access to safe water and food as well as lack of environmental and personal hygiene favor the spread of many infectious diseases. Epidemic typhus, plague, malaria, cholera, typhoid fever, hepatitis, tetanus, and smallpox have nearly constantly accompanied wars, frequently deeply conditioning the outcome of battles/wars more than weapons and military strategy. At the end of the nineteenth century, with the birth of bacteriology, military medical researchers in Germany, the United Kingdom, and France were active in discovering the etiological agents of some diseases and in developing preventive vaccines. Emil von Behring, Ronald Ross and Charles Laveran, who were or served as military physicians, won the first, the second, and the seventh Nobel Prize for Physiology or Medicine for discovering passive anti-diphtheria/tetanus immunotherapy and for identifying mosquito Anopheline as a malaria vector and plasmodium as its etiological agent, respectively. Meanwhile, Major Walter Reed in the United States of America discovered the mosquito vector of yellow fever, thus paving the way for its prevention by vector control. In this work, the military relevance of some vaccine-preventable and non-vaccine-preventable infectious diseases, as well as of biological weapons, and the military contributions to their control will be described. Currently, the civil-military medical collaboration is getting closer and becoming interdependent, from research and development for the prevention of infectious diseases to disasters and emergencies management, as recently demonstrated in Ebola and Zika outbreaks and the COVID-19 pandemic, even with the high biocontainment aeromedical evacuation, in a sort of global health diplomacy.

Epidemiological and clinical aspects of hepatitis B virus infection in Italy over the last 50 years

A relevant gradual reduction of both the incidence rate of acute hepatitis B (AHB) and prevalence of chronic hepatitis B has occurred in Italy in the last 50 years, due to substantial epidemiological changes: Improvement in socioeconomic and hygienic conditions, reduction of the family unit, accurate screening of blood donations, abolition of re-usable glass syringes, hepatitis B virus (HBV)-universal vaccination started in 1991, use of effective well tolerated nucleo(t)side analogues able to suppress HBV replication available from 1998, and educational mediatic campaigns against human immunodeficiency virus infection focusing on the prevention of sexual and parenteral transmission of infections. As an example, AHB incidence has gradually decreased from 10/100000 inhabitants in 1985 to 0.21 in 2020. Unfortunately, the coronavirus disease 2019 (COVID-19) pandemic has interrupted the trend towards HBV eradication. In fact, several HBV chronic carriers living in the countryside have become unable to access healthcare facilities for screening, diagnosis, clinical management, and nucleo(t)side analogue therapy in the COVID-19 pandemic, mainly for anxiety of becoming infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), movement restrictions, and reduced gains from job loss. In addition, one-third of healthcare facilities and personnel for HBV patients have been devolved to the COVID-19 assistance.

Evolution of the incidence of hepatitis B virus infection and immunization rates in a large French cohort born between 1960 and 1994

In France, several successive changes in anti-hepatitis B virus (HBV) vaccination policies occurred since 1982. We estimated the incidence and prevalence of HBV infection according to years of birth 1960 to 1994 in a large sentinel cohort to evaluate the epidemiology of HBV during vaccination policy changes. A retrospective cohort study included data from all HIV, HBV and hepatitis C virus (HCV) screening facilities in Grand Lyon. From 2005 to 2010, all 57113 individuals with complete HBV serologic status were enrolled. Survival analyses modeled separately various ages in each birth cohort. The proportion of immunized individuals increased in birth cohorts 1978 to 1984 (up to 58.3% (95% confidence interval (CI), 43.3-68.2 at age 15). In post-1985 birth cohorts, this proportion decreased to 19.5% (95% CI, 15.5-24) in birth cohort 1987 at age 15. Probability of past or current HBV infection increased constantly in birth cohorts 1960 to 1967, up to 12% (95% CI, 10.4-14) at age 30, then decreased gradually in birth cohorts 1968 to 1991, down to 0.9% (95% CI, 0.7-1.2) at age 17.5. In post-1991 cohorts, the probability of HBV infection increased again, up to 2.5% (95% CI, 1.7-3.6) at age 17.5. HBV incidence fluctuated between 5 and 8 per 1000 person-years in pre-1986 birth cohorts, decreased to 2.1 (95% CI, 1.5-2.7) in birth cohorts 1986 to 1991 but rebounded to 5 (95% CI, 3.5-7.1) in post-1991 birth cohorts. HBV incidence was remarkably high in young adults with noticeable variations concomitantly to vaccination policy changes. A dramatic decline in immunization rate was temporally associated with a sharp rebound of infection after withdrawal of systematic adolescent vaccination in 1998.

Hepatitis B prevalence and incidence in Greenland: a population-based cohort study

Greenland remains a highly endemic area for hepatitis B virus (HBV) infection. This is in sharp contrast to other modern societies, such as Denmark. To address this discrepancy, we investigated the natural history of HBV infection in Greenland by estimating the age-specific incidence of HBV infection, the proportion of chronic carriers, and the rates of hepatitis B surface antigen seroclearance. In total, 8,879 Greenlanders (16% of the population) from population-based surveys conducted in 1987 and 1998 were followed through March 2010. Data on HBV status were supplemented by HBV test results from all available HBV registries in Greenland to determine changes in HBV status over time. Incidence rates of HBV infection and hepatitis B surface antigen seroclearance were estimated after taking into account interval censoring. The incidence of HBV infection in 5-14-year-old subjects was less than 1 per 100 person-years and peaked at 5 per 100 person-years in persons 15-24 years of age. Overall, 17.5% of persons infected in adulthood were estimated to become chronic carriers. HBV is primarily transmitted in adolescence and adulthood in Greenland. In contrast to what is observed in most other populations, HBV-infected adults in Greenland have a high risk of progressing to chronic HBV carriage. This phenomenon might explain how the high rate of infection is maintained in Greenland.

Epidemiology of acute and chronic hepatitis B and delta over the last 5 decades in Italy

The spread of hepatitis B virus (HBV) infection has gradually decreased in Italy in the last 5 decades as shown by the steady reduction in the incidence rates of acute hepatitis B, from 10/100000 inhabitants in 1984 to 0.85/100000 in 2012, and by the reduced prevalence of hepatitis B surface antigen (HBsAg)-positive cases among chronic hepatitis patients with different etiologies, from 60% in 1975 to about 10% in 2001. The prevalence of HBsAg chronic carriers in the general population also decreased from nearly 3% in the 1980s to 1% in 2010. Linked to HBV by its characteristics of defective virus, the hepatitis delta virus (HDV) has shown a similar epidemiological impact on the Italian population over time. The incidence of acute HDV infection decreased from 3.2/100000 inhabitants in 1987 to 0.8/100000 in 2010 and the prevalence of HDV infection in HBsAg chronic carriers decreased from 24% in 1990 to 8.5% in 2006. Before the beneficial effects of HBV mass vaccination introduced in 1991, the decreased endemicity of HBV and HDV infection in Italy paralleled the improvement in screening blood donations, the higher standard of living and impressive reduction in the birth rate associated with a marked reduction in the family size. A further contribution to the decline in HBV and HDV infections most probably came from the media campaigns to prevent the spread of human immunodeficiency virus infection by focusing the attention of the general population on the same routes of transmission of viral infections such as unsafe sexual intercourse and parenteral exposures of different kinds.

Clinical and molecular characterization of chronic hepatitis B in Albania: a country that is still highly endemic for HBV infection

Albania is a Mediterranean country, still with a high endemicity level of hepatitis B virus (HBV) infection. The chronic hepatitis B profile was characterized in this geographical area and used as a model to investigate the impact of endemicity level on the prevalence of the two major forms of chronic hepatitis B (HBeAg-positive and HBeAg-negative chronic hepatitis B). A cross-sectional study was conducted among 62 chronic hepatitis B patients consecutively admitted to the most important tertiary health care center for the diagnosis and treatment of liver disease in Albania. HBV-DNA was measured with an in-house PCR with a sensitivity of 10(4) copies/ml which uses primers encompassing the pre-core/core region. PCR products were subjected to sequencing and oligohybridization assay. Of the 62 patients, 75.8% had HBeAg-negative chronic hepatitis B. Genotype D was found in all 39 patients with detectable HBV viremia, for whom the heterogeneity of the region modulating HBeAg expression was assessed. Basic core promoter (BCP) mutations (1762/1764) were observed more often in anti-HBe-positive and older patients. In more than 90% of the HBeAg-negative chronic hepatitis B patients with detectable viremia, HBV that carries the G to A pre-core mutation at nucleotide 1896 was found. Patients with HBeAg-positive chronic hepatitis B were younger than HBeAg-negative chronic hepatitis B patients, and for symptomatic and asymptomatic liver-disease patients, the age of peak prevalence was at least 10 years lower for HBeAg-positive chronic hepatitis B patients. In conclusion, the virological and clinical pattern of chronic hepatitis B in Albania is similar to that observed in other Mediterranean countries; it seems to be independent of the HBV endemicity level.

An estimate of the current risk of transmitting blood-borne infections through blood transfusion in Italy

We conducted a retrospective cohort study to estimate the incidence of major blood-borne agents among Italian blood donors and calculated the risk of infection among blood recipients using the 'incidence/window period model'. The study was conducted among 46 180 blood donors enrolled in six blood centres between 1994 and 1999. During follow-up, seven new infections were confirmed: three donors seroconverted for anti-human immunodeficiency virus (HIV); two for anti-hepatitis C virus (HCV); and two showed hepatitis B surface antigen (HBsAg) reactivity; no cases of syphilis were observed. The incidence rates per 100 000 person/years were: 4.06 (95% CI: 0.82-11.85) for HIV; 2.41 (95% CI: 0.29-8.70) for HCV; and 2.70 (95% CI: 0.32-9.77) for HBsAg; the incidence for total hepatitis B virus (HBV) infection was 9.77 per 100 000 person/years (95% CI: 1.16-35.36). The estimated risk of an infectious blood unit not being detected was: 2.45 (95% CI: 0.13-12.33) per 1 million units for HIV; 4.35 (95% CI: 0.30-22.39) for HCV; and 15.78 (95% CI: 1.16-84.23) for HBV. Overall, an estimated 22.58 per 1 million units are infected. In Italy, the risk of transfusion-transmitted infections is low and is similar to that in other western countries. The introduction of new more sensitive screening tests could reduce the residual risk of transfusion-transmitted infection by 40-80%.

Surveillance of infectious diseases in the Italian military as pre-requisite for tailored vaccination programme

Surveillance and control of infectious diseases in the Italian military include prompt reporting of all occurring cases and prophylaxis through compulsory vaccination practices. The last mandatory immunisation programme in the Italian military was launched in 1998 (more than 10 years after the previous programme was introduced in 1986-1987) and it was planned according to the epidemiological data herein reported. The incidence rates (number of cases x 100000 subjects) of infectious diseases notified during the period 1976-1980 were compared with the corresponding figures notified 15 years later (1991-1995). An increase of three airborne-transmitted viral diseases--varicella, rubella and measles--counterbalanced by a decrease of other infectious diseases, such as mumps, typhoid fever, tuberculosis, viral hepatitis, scabies, syphilis and gonorrhea, was observed. This may be related to improvements in the general hygienic conditions and more responsible sexual behaviour among Italian military recruits. Moreover, incidence rates of cases notified in the military were compared with those notified in the general population of the same sex- and similar age-range (15-24 years) over a 12-year period (1986-1997), to monitor the epidemiological situation in relation to (a) potential risk factors specifically linked to military life and (b) protective effects induced by specific vaccinations. Airborne-transmitted viral diseases, such as varicella, rubella, measles and mumps--which are usually underreported among civilians--show higher incidence rates in the military. Meningococcal meningitis shows higher incidence rates in the military in 1986 and 1987 (before the introduction of mandatory specific vaccination) as well as in 1995-1997 (main etiologic agent N. meningitidis serogroup B); similar rates were instead observed in the other years. Incidence rates for typhoid fever are generally lower in the military, despite the community life, probably reflecting the protective efficacy of specific vaccine. Hepatitis A and B show similar rates between military and civilian population. Finally, pulmonary tuberculosis generally shows higher rates in the military. These data therefore allow the conclusion that the only infectious diseases, for which possible risk factors in the military life may be hypothesised, seem to be meningococcal meningitis and perhaps pulmonary tuberculosis. Epidemiological surveillance of infectious diseases in the military as a pre-requisite for appropriate public health intervention strategy represents a good model to be followed also in larger contexts.