**10. Immunization program for travelers**

Several reasons why people did not opt for pre-travel vaccinations include traveler's pre-knowledge regarding the prevention of diseases during overseas travel, the limited number of healthcare settings that gives immunization, and that some countries have not yet approved the number of vaccines a traveler needs [9, 31].

There are commercially hepatitis B vaccines available currently, for example, recombinant HBV vaccine (Engerix-B®, GlaxoSmithKline, and Recombivax HB®, Merck & Co., Inc.) and the HAV and HBV combined vaccine (Twinrix®, GlaxoSmithKline) [78]. The complete HBV vaccination requires three shots of vaccine. The normal timeline of the three intramuscular injections is to have the second and third injections given 1 and 6 months after the first dose. An accelerated schedule (doses on days 0, 7, and 21 and then a post-travel dose at 12 months) might be required if there is an inadequate time for immunization prior to travel [79, 80]. An HBV vaccine can also be used to treat persons who have been exposed to the virus, in order to prevent disease development [31].

The prevalence of HBV differs between countries and regions, and therefore the number of persons acquiring protective immunity from a previous HBV infection also changes. Therefore, the recommendation of its vaccination should be hinged on likelihood of infection during travel and evidence of previous immunization or recovery from previous infection [74]. In those travelers without evidence of previous HBV immunity, HBV vaccination is recommended in those with HBV exposure risks and traveling to HBV endemic regions [78]. The CDC has recommend HBV vaccination to all persons without evidence of immunization before traveling to areas with intermediate and high prevalence of chronic hepatitis B and, irrespective of the traveler's destination, and based on the traveler's potential risky activities and exposures [11, 81]. High-risk activities might include unprotected sex with a new partner, getting a tattoo or piercing, or having any medical procedures like surgery [11, 81]. Studies have reported that only 19% of all American travelers and 30% of American travelers planning high-risk activities had received a completed HBV vaccination before departure irrespective of the recommendation made by the CDC [79]. This finding is in consonance with information from Europe that only 15% of international travelers to HBV endemic regions receive a completed HBV vaccination before travel [79]. There is often a very low immunity of HBV to travelers from low endemic regions and those born before the EPI schedules [82, 83]. Obviously, there are no recommendations for HBV serologic examination of international travelers currently. This might be because of the large population of international travelers, thus making it impossible to screen all for the virus. Reports have it that only 3.4–3.9% of the population in low endemic countries will have evidence of the HBV serologic markers prior infection [82, 83]. Vaccination of those populations should be considered when long-term travel is arranged to countries where HBV prevalence is intermediate or hyperendemic [31].

**309**

*Traveler's Infections: Overview of Hepatitis B Virus Infection*

There are several antiviral treatments available for chronic HBV infection, and everyone with chronic HBV should be linked to care, considered for treatment, and checked for liver damage and liver cancer regularly [84]. Therapy of HBV reduces the amount of virus in the system and lowers the chance of developing to serious liver disease and liver cancer. However, most people cannot be cured of the viral

Worthy of note is the fact that there are currently two main antiviral drugs for the treatment of chronic HBV infection [87]. They are nucleos(t)ide analogues (NA) and interferon (IFN) including normal IFNs and pegylated IFNs (Peg-IFNs). NA gives a direct antiviral effect by stopping DNA polymerase. It is usually given orally. There are six types of NAs as approved for treatment of HBV by the WHO: Lamivudine (LAM), Adefovir (ADV), Telbivudine (TBV), Entecavir (ETV), Tenofovir disoproxil fumarate (TDF), and Tenofovir alafenamide (TAF). IFNs, especially the Peg-IFNs, have a suppressed antiviral effect than the NA therapy, but its persistent effect can be achieved with a finite therapy. It is usually given via subcutaneous injection. There are reports of combination therapy of

There are serious ongoing clinical trials for the development of more effective

Early screening and treatment will help mitigate frequent transmission of the viral agent and curb morbidities and mortalities in infected persons [85]. The first line should be to give the exact medical advice and start antiviral treatment, if available. Sadly, undergoing this step is often a problem in developing regions where there is lack of access to good healthcare facilities, and antiviral treatment is often

Advocacy of immunization exercise for HBV infection should be key in eliminating the viral agent worldwide which is central to WHO's agenda [6, 10]. To maximize implementation of the WHO agenda, provision of technical guidance and support to reduce transmission of the disease such as adhering to safer blood transfusion and disposable needles among others. The virus vaccine is very effective in preventing disease progression. It has been reported that only 27% of newborn babies had receive a birth dose of hepatitis B vaccine globally [86]. Birth dose vaccination of the viral agent is fundamental to halting mother-to-child transmission as late immunization is not fully effective in destroying the chain of mother-to-child transmission. Coordination between maternal health services and immunization

Self-protection measures are one of the pre-travel counseling given to potential travelers to HBV and other blood-borne pathogen endemic regions [7, 8, 43]. Persons should be guided from contaminated items or equipment used in medical

agent, and as such therapy is recommended to continue for life [85, 86].

*DOI: http://dx.doi.org/10.5772/intechopen.92174*

**11. Treatment of HBV infection**

NA + NA and Peg-IFN + NA [86, 87].

**12.1 Early screening and treatment**

**12.2 Advocacy of immunization exercise**

should be effectively established [88].

**12.3 Self-protection measures**

exorbitant [6, 86].

treatments and a cure for HBV infection [3, 6].

**12. Way forward in curbing HBV as a traveler's infection**
