Risk of viral hepatitis among military personnel assigned to US Navy ships

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.

A Systematic Review for Vaccine-Preventable Diseases on Ships: Evidence for Cross-Border Transmission and for Pre-Employment Immunization Need

A literature review was conducted to identify evidence of cases and outbreaks of vaccine-preventable diseases (VPDs) that have been reported from on board ships and the methods applied on board for prevention and control, worldwide, in 1990 to April 2019. Moreover, evidence from seroprevalence studies for the same diseases were also included. The literature review was conducted according to Preferred Reporting Items for Systematic reviews (PRISMA) guidelines. A total of 1795 cases (115 outbreaks, 7 case reports) were identified, the majority were among crew (1466/1795, 81.7%) and were varicella cases (1497, 83.4%). The origin of crew cases was from sub-tropical countries in many reports. Measles (40 cases, 69% among crew), rubella (47, 88.7%), herpes zoster (9, 69.2%) and varicella cases (1316, 87.9%) were more frequent among crew. Mumps cases were equal among passengers and crew (22/22). Hepatitis A (73/92, 70.3%), meningococcal meningitis (16/29, 44.8%), and pertussis (9/9) were more frequent among passengers. Two outbreaks resulted in 262 secondary measles cases on land. Review results were used to draft a new chapter for prevention and control of VPDs in the European Manual for Hygiene Standards and Communicable Disease Surveillance on Passenger Ships. Despite past and current evidence for cross-border VPD transmission and maritime occupational risks, documented pre-employment examination of immune status, vaccination of seafarers, and travel advice to passengers are not yet regulated.

Computational modeling of interventions and protective thresholds to prevent disease transmission in deploying populations

Military personnel are deployed abroad for missions ranging from humanitarian relief efforts to combat actions; delay or interruption in these activities due to disease transmission can cause operational disruptions, significant economic loss, and stressed or exceeded military medical resources. Deployed troops function in environments favorable to the rapid and efficient transmission of many viruses particularly when levels of protection are suboptimal. When immunity among deployed military populations is low, the risk of vaccine-preventable disease outbreaks increases, impacting troop readiness and achievement of mission objectives. However, targeted vaccination and the optimization of preexisting immunity among deployed populations can decrease the threat of outbreaks among deployed troops. Here we describe methods for the computational modeling of disease transmission to explore how preexisting immunity compares with vaccination at the time of deployment as a means of preventing outbreaks and protecting troops and mission objectives during extended military deployment actions. These methods are illustrated with five modeling case studies for separate diseases common in many parts of the world, to show different approaches required in varying epidemiological settings.

Hepatitis B virus among Saudi National Guard personnel: seroprevalence and risk of exposure

BACKGROUND

Data on HBV prevalence among active military personnel in Saudi Arabia (SA) are lacking. In addition, the work-related risk of exposure is unclear. The objective of this study was to estimate the seroprevalence of HBV and the risk of HBV exposure among SA National Guard (SANG) soldiers.

METHODS

A cross-sectional study was performed and included 400 male SANG soldiers working in Jeddah during January 2009. All soldiers completed a questionnaire to assess their risk of exposure and gave a blood sample to test for hepatitis serology markers.

RESULTS

A total of 16 (4.0%) soldiers were positive for HbsAg, 53 (13.2%) were positive for anti-HBc, and 230 (57.5%) were positive for anti-HBs. None of the soldiers had acute HBV infection, but 15 (3.8%) were chronic HBV carriers. A total of 152 (38.0%) soldiers were susceptible to HBV infection, and 230 (57.5%) were immune to HBV infection, primarily (84.3%) due to HBV vaccination. Compared with those who were negative for anti-HBc (never exposed), soldiers who were positive for anti-HBc were more likely to be older, have a lower education level, have a higher income, have a longer service duration, have a household member with HBV disease, have undergone surgery, or have undergone endoscopy. In the multivariate logistic regression model, older age, presence of a household member with HBV disease and previous endoscopy were independent predictors of HBV exposure.

CONCLUSION

We report a 4% prevalence of HBsAg in the Saudi military population. This HBV prevalence was higher than those in the general Saudi population and military populations from Western countries. Both work-related and community-related risk factors for exposure are suggested.

Risk groups for hepatitis A virus infection

We report the conduct and results of a systematic search for evidence of risk of infection with hepatitis A virus (HAV) among blood transfusion recipients, travellers, the military, healthcare workers, sewage workers, foodhandlers, day care assistants, institutionalised subjects, blood transfusion recipients, drug addicts, homosexuals, prisoners and other risk groups such a liver transplantees. We report our recommendations for the use of the HAV vaccine in these groups.

Endemic infectious diseases of Afghanistan

The current crisis in Afghanistan has resulted in an influx of Western military personnel, peacekeepers, humanitarian workers, and journalists. At the same time, unprecedented numbers of internally displaced persons and refugees have overwhelmed much of the already fragile infrastructure, setting the stage for outbreaks of infectious diseases among both foreigners and local populations. This review surveys the literature concerning the infectious diseases of Afghanistan and south-central Asia, with particular emphasis on diseases not typically seen in the Western world.

Seroprevalence of hepatitis A, B and C markers in Greek warship personnel

A seroepidemiological study was conducted to assess the seroprevalence of hepatitis A, B and C markers in 285 males (mean age: 24.4+/-4.4 years) aboard a Greek warship. Two hundred and sixty three serum samples were tested. None was found to be positive for HAV antibodies, three persons (1.1%) were positive for HBsAg, four persons (1.5%) were positive for anti-HBc and one person (0.4%) was positive for anti-HCV. Forty-five persons (17.1%) had developed titles anti-HBs > 10 IU/L. The establishment of a vaccination policy against hepatitis A among warship personnel is strongly recommended.

Prevention of sexually transmitted diseases and HIV in young military men: evaluation of a cognitive-behavioral skills-building intervention

BACKGROUND

Military personnel deployed to foreign countries with high endemic rates of sexually transmitted diseases (STDs) are at risk.

GOAL

To evaluate a cognitive-behavioral, skills-building intervention to prevent STDs in junior, enlisted, male US Marines deployed to the Western Pacific aboard ships with periodic liberty visits to foreign ports.

STUDY DESIGN

This study, using a quasi-experimental design, assigned 584 men to a cardiopulmonary resuscitation training (n = 288) or a cognitive-behavioral intervention (n = 296). The intervention aimed to increase prevention knowledge, reduce high-risk psychosocial (motivation) factors, and build decision-making and communication skills to reduce risky sexual behaviors and alcohol consumption.

RESULTS

Participation in the intervention was associated with increased knowledge regarding symptoms and treatment of STDs and HIV (P < 0.001), decreased alcohol use (P < 0.01), and sexual risk (P < 0.01) during liberty ports of call.

CONCLUSION

A multiple-session, cognitive-behavioral, skills-building intervention can be successfully implemented for deployed military personnel.

Hepatitis A: old and new

The hepatitis A virus (HAV), a picornavirus, is a common cause of hepatitis worldwide. Spread of infection is generally person to person or by oral intake after fecal contamination of skin or mucous membranes; less commonly, there is fecal contamination of food or water. Hepatitis A is endemic in developing countries, and most residents are exposed in childhood. In contrast, the adult population in developed countries demonstrates falling rates of exposure with improvements in hygiene and sanitation. The export of food that cannot be sterilized, from countries of high endemicity to areas with low rates of infection, is a potentially important source of infection. After ingestion and uptake from the gastrointestinal tract, the virus replicates in the liver and is excreted into the bile. Cellular immune responses to the virus lead to destruction of infected hepatocytes with consequent development of symptoms and signs of disease. Humoral immune responses are the basis for diagnostic serologic assays. Acute HAV infection is clinically indistinguishable from other causes of acute viral hepatitis. In young children the disease is often asymptomatic, whereas in older children and adults there may be a range of clinical manifestations from mild, anicteric infection to fulminant hepatic failure. Clinical variants include prolonged, relapsing, and cholestatic forms. Management of the acute illness is supportive, and complete recovery without sequelae is the usual outcome. Research efforts during World War II led to the development of passive immunoprophylaxis. Pooled immune serum globulin is efficacious in the prevention and attenuation of disease in exposed individuals. More recently, active immunoprophylaxis by vaccination has been accomplished. Future eradication of this disease can now be contemplated.

Investigations of the epidemiology of infections with hepatitis A virus in Jamaica

Between January 1995 and August 1998, a study was conducted to elucidate the epidemiology of hepatitis A virus (HAV) in Jamaica. Participants were recruited from six sites across the island. The potential risk factors for transmission which were studied included age of the individual, gender, residence (urban v. rural area), sanitary facilities (flush toilet v. pit) and source of domestic water (indoor plumbing v. other). There were 128 male subjects and 211 female, aged 3-90 years. The mean ages of the males and females were 24.9 and 25.6 years, respectively. The seroprevalence of HAV in the study population, estimated by ELISA, was 59.9%. Logistic regression indicated that age (P < 0.001) and source of domestic water (P = 0.006) were the major contributors to exposure to HAV. The rate of exposure to the virus was seen to increase with age. By the age of 10 years, 30% of children had been exposed, and almost 100% of the oldest subjects were seropositive. Rates of exposure to HAV were higher among households which had external sources of water, including standpipes, rivers and tanks, than those with indoor plumbing. Although the seroprevalence of HAV in Jamaica is similar to that seen in developing countries, the age-related pattern of exposure mirrors the pattern seen in developed countries.

Seroprevalence of viral hepatitis A in the Czech Republic

Over recent decades, the epidemiology of hepatitis A has changed in most European countries: the age of infection has been shifting towards older age groups. In view of this evolution and the central location of the Czech Republic in Europe, we wanted to assess current anti-hepatitis A seroprevalence. We determined the anti-hepatitis A seroprevalence among three different groups: military personnel between 1991-1995, prior to their deployment as UN troops, civilians participating in a national serological survey in 1996 and volunteers for vaccine clinical trials in 1996. The anti-HAV prevalence <20 years of age was about 4%; in the age cohort 40-49 it ranged between 47 and 51%. Only over the age of 60 years was the seroprevalence rate >85%. The risk of acquiring HAV is low for younger age groups. We could demonstrate some regional differences with higher rates in some age strata for the North Bohemian region and the lowest rates in East Bohemia and Prague. Compared to archived sera from a previous serological survey in 1984 we demonstrate a shift towards low endemicity. For the first time it is shown that an Eastern European country, i.e. the Czech Republic, is a country with a low endemicity for HAV. Substantial parts of the population are or will be at an increased risk of HAV infection and active immunisation against HAV should be considered.

The first combined vaccine against hepatitis A and B: an overview

Hepatitis A and B infections are prevalent world-wide and are a significant cause of morbidity and mortality. A vaccine providing dual protection against hepatitis A and B is now available (Twinrix, SmithKline Beecham Biologicals). Six pivotal vaccine trials, involving 843 healthy adults, aged between 17 and 60 years and vaccinated following a 0, 1, 6 month schedule are discussed. At month 2 more than 99% of the vaccinees were seropositive for anti-HAV and 84% were protected against hepatitis B. The third dose induced a 12-fold increase in geometric mean titres (GMTs) to 5404 mIU/ml. One month after completion of the vaccination course nearly all vaccinees had protective titres against hepatitis B with a GMT of 4818 mIU/ml. Long term follow-up data until month 48 is available for two studies. At month 48 all 129 vaccinees sampled were still positive for anti-HAV antibodies and > 95% were still protected against hepatitis B. The combined hepatitis A and B vaccine Twinrix proves to be consistently safe, well tolerated and highly immunogenic and compares well with serological responses reached with monovalent vaccines. This combined hepatitis A and B vaccine offers more convenience, potentially better compliance and lower administration costs.

Incidence and relative risk for hepatitis A, hepatitis B and tuberculosis and occurrence of malaria among merchant seamen

The purpose of the study was to assess the incidence and relative risk of hepatitis A and B and tuberculosis among Danish merchant seamen. We also assessed the occurrence of malaria. The study was based on record linkage of a research database containing data on 24,132 Danish male seamen and the Registry for Notifiable Infectious Diseases in Denmark, supplemented by data from other sources. The standardized incidence ratio (SIR) for hepatitis A for male seamen was 1.77 (0.91-3.10) as compared with the incidence in the general population. The incidence was 0.9 notified cases/10,000 years. The SIR for hepatitis B for male seamen was 3.02 (1.79-4.78), the main risk factors being intravenous drug use and casual sex abroad. Tuberculosis was not more common among seamen than in non-seamen. The results have implications for vaccination strategies in this occupational group. Malaria occurred frequently in the seamen, especially among those involved in West African trade. Irregular use of malaria prophylaxis and probably chloroquine resistance were of importance in some cases. To detect further cases of hepatitis A and B and malaria, other sources were reviewed. Only a few extra cases were identified. The registry of notifiable infectious diseases was thus found to be rather complete.

Cancer incidence among Filipinos in Los Angeles County, 1972-1991

Although Filipinos are the second largest Asian subgroup in the United States, little is known about their patterns of cancer incidence. We have examined cancer incidence rates among Filipinos living in Los Angeles County from 1972 through 1991 and evaluated their risk of non-localized cancer relative to non-Hispanic whites. Although Filipinos have substantially lower cancer rates than non-Hispanic whites in Los Angeles County, their incidence rates of liver cancer, cancer of the nasopharynx and thyroid cancer are higher. Filipino men and women had somewhat more advanced cancer at diagnosis, on average, than non-Hispanic whites, though no statistically significant differences were observed for sites where early detection methods exist. Our data suggest that Filipino-Americans would benefit from increased screening for cervical and breast cancer as well as efforts to interrupt transmission of hepatitis B virus to reduce liver cancer incidence.

Risk factors for hepatitis A, B and C virus infection among Swedish expatriates

The influence of different risk factors for viral hepatitis A, B and C, particularly if sexual contact with the indigenous population was related to an increased risk of having hepatitis B virus (HBV) markers, was assessed by multivariate analysis in a logistic regression model in a prospectively enrolled series of 563 adult Swedish expatriates. The most frequently reported recognised risk factors for the acquisition of viral hepatitis (as reported in a self-administered questionnaire) were having received an inoculation during medical or dental treatment, reported by 45% of all subjects, and having had sexual contact with the indigenous population, reported by 35%. Whilst the prevalences of hepatitis A virus (HAV) and hepatitis C virus (HCV) markers in these expatriates were of the same magnitude as previously reported in the general Swedish population, 8% and 0.3%, respectively, the prevalence of markers for a past or present HBV infection was about twice as high (5%). The presence of HBV markers was associated with being a health care professional or having received inoculations during medical or dental treatment in Africa. No significant association was found between having HBV markers and having had sexual contact with the indigenous population.

Antibodies against hepatitis viruses in merchant seamen

Seamen constitute a special group of international travellers who may run an increased risk of contracting hepatitis, because of visits to foreign ports and the particular environment on board ship. The purpose of the survey was to assess the prevalence of serological markers for hepatitis A, B and C virus infection among seamen and to identify present and previous risk factors for infection. 515 seamen were studied. The prevalence of antibodies against hepatitis A was 0.3% in subjects below 40 years of age, increasing with age above 40 years, and highest among those who had sailed in international trade. The prevalence of antibodies against hepatitis B was 2.7% in subjects below 40 years of age, increasing to 35.7% in the group above 60 years of age. Hepatitis C antibodies occurred in 1.2%. Vaccination of sailors against hepatitis A should follow the same recommendations as to other travellers. The prevalence of hepatitis B was higher than in reference groups of non-seamen but, because hepatitis B is only one of many blood-borne diseases, prevention should be directed towards changes in behaviour rather than vaccination, except for special groups. Young seamen in international trade were found to be most at risk of contracting sexually transmitted diseases.

Exposure to enteroviruses and hepatitis A virus among divers in environmental waters in France, first biological and serological survey of a controlled cohort

An epidemiological study of hepatitis A and enteroviruses was conducted in a military diving training school, by evaluating the viral contamination of water using an ultrafiltration concentration technique, and assessing seroconversion and the presence of virus in stool specimens obtained from 109 divers and 48 controls. Three of 29 water specimens were positive for enterovirus by cell culture and 9 by molecular hybridization. There was little or no risk of virus infection during the training course (49 h exposure) because there was no significant difference between divers and controls for both viral isolation and seroconversion. However, a higher percentage of coxsackievirus B4 and B5 seropositive divers suggests that these were more exposed during previous water training. No hepatitis A virus (HAV) detection and no seroconversion to HAV was observed. The rate of HAV seropositive subjects was 17% in this 24.5-year-old population.

Incidence of hepatitis A virus infection among an Italian military population

In 1990, a prospective serological survey to estimate the rate of clinical and inapparent infection with hepatitis A virus (HAV) was performed in a cohort of 1,268 soldiers, 18-24 years old, during an 8 month period in the Campania region in Italy. At the time of enrollment 318 (25%) of the 1,268 soldiers were positive for total antibodies to HAV (anti-HAV). None of them was positive for IgM anti-HAV. Among the 950 susceptible subjects who were followed up for 8 months, eight (0.8%) later seroconverted to anti-HAV positivity. This figure corresponds to an incidence of 1.3/100 person/years (eight seroconversions during 633.3 years of observation). There were two clinical (with presence of IgM-anti-HAV) and six inapparent infections. The clinical/subclinical HAV ratio was 1:3. These findings indicate that the risk of HAV infection among soldiers residing in this area is not negligible.

Geographic risk factors for viral hepatitis and cytomegalovirus infection among United States Armed Forces blood donors

In an effort to determine whether residence in a foreign country increases the risk of hepatitis B and C and cytomegalovirus (CMV) infection in United States (US) Armed Forces blood donors, 5719 volunteer donors at four US Navy blood banks were evaluated. Most participants were repeat donors (68%) and were young (mean age, 25 years), male (88%), and white (80%), black (10%), or Hispanic (7%). Birth outside of the United States was reported by 6 percent of subjects, and 34 percent had lived in a foreign country for more than 3 months. Twenty (0.3%) subjects had hepatitis B surface antigen (HBsAg), and 100 (1.7%) had antibody to hepatitis B core antigen (anti-HBc). Thirty-four (0.6%) were repeatably reactive in enzyme-linked immunosorbent assay for antibody to hepatitis C virus (anti-HCV); 11 (0.2%) had anti-HCV in immumoblot assay. Of the 3484 donors tested for anti-CMV, 1117 (32.1%) were positive. When demographic characteristics were controlled for both anti-HBc and anti-CMV seropositivies were independently associated in male blood donors with residence in the Philippines. Geographic factors were not associated with HBsAg and anti-HCV positivity. These findings indicate that the prevalence of serologic markers for viral hepatitis is low in military blood donors, but that residence in the Western Pacific is a risk factor for hepatitis B and CMV infection.