**5. How HBV infection is transmitted**

Transmission of HBV in travelers is through percutaneous or mucosal exposure to HBV-infected blood or bodily fluids including saliva or semen [30, 31]. There are reports of transmission via sexual contact, contaminated blood and its products, and contaminated medical equipment and through sharing of infected needles and injecting apparatus [31, 32].

In SSA, the viral infection, is often disseminated through perinatal and horizontal route, while in the developed regions, most infections occur in adults of younger ages through injecting drug use or high-risk sexual behavior (e.g., bisexuals and homosexuals) [8, 33]. HBV infection is known to be transmitted from the mother to child and it is a thing of worry [34, 35]. Every year, about 25,000 infants are born to HBV-diagnosed mothers in the United States, and approximately 1000 mothers transmit HBV to their infants. This means that about 90% of HBV-infected newborns will eventually develop to chronic infection, and up to 25% of those infected at birth will eventually die prematurely due to HBV-related complications. Therefore, the standard care for pregnant women includes an HBV testing during each pregnancy, to prevent HBV-positive pregnant women from transmitting the viral agent to her unborn child [34, 35].

Inadequate infection control in healthcare settings also constitutes to a significant mode of HBV transmission. That is why immigrants from many countries are recommended to be tested for HBV [12]. Transmission by blood transfusion is now rare, whereas before screening of donor blood, it was not uncommon [32]. Cord blood is usually negative for the serological markers of HBV, but occasionally intrauterine infection might happen. Fetal blood sampling might enhance this risk, but amniocentesis does not appear to increase the chances of intrauterine transmission [36]. Infection presumably occurs at or soon after birth. It perhaps occurs through breast (feeding) milk, as it is known to carry the virus. Transmission could occur if there was an in apparent breach in the mucosa of the mouth or during teething [37]. Among adults, high-risk sexual activity is one of the most frequent routes of transmission for HBV [38]. Historically, male homosexual contacts have been associated with a high risk for the viral infection [38]. Sexual transmission accounts for a majority of the transmission occurring in adult life [38]. More recently, heterosexual transmission is reported to be the most common cause of acute HBV infection in adults [39]. Transmission may also continue to occur in healthcare settings. It is a result of nonadherence to isolation guidelines in a hemodialysis unit, or direct person-person exposure (e.g., surgeon-to-patient or dentist-to-patient) may transmit the virus [40]. Sharing of clothes and bed spaces could pose jeopardy because the virus could be found in saliva, tears, urine, breast milk, and any other body fluid [13]. Other possible means of transmission include an infected parent kissing the cut finger or scraped knee of his child and sharing of personal items of personal hygiene such as toothbrushes between parents and children [3].

#### **6. Epidemiologic studies of HBV infection in travelers**

There is insufficient information that depicts predisposing factors to travelers; however, there is scarcity of public reports of HBV infection in travelers, and there is low risk for travelers who are not engaged in high-risk behaviors [7]. The risk of the viral infection might increase in countries/regions that have a 2% prevalence of chronic HBV infection, such as in the African and Western Pacific regions; missionaries, long-term community development workers, and expatriates might be at high risk for the viral agent in such areas [41]. Travelers should take note on how

**305**

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

medical treatments that will require the same risks of exposure.

the virus is acquired and take precautionary measures to mitigate transmission. The risk of injury due to accident is much higher for travelers than for people in their own environment. These injuries may involve medical attention that will require injections, IVs, or blood transfusions, thereby enhancing the risk of HBV exposure [7]. Older aged travelers, especially those with heart problems, may also require

The global prevalence of HBV indicated by the proportion of chronic HBV carriers in the population that is seropositive for the hepatitis B surface antigen (HBsAg) varies strongly between different geographical regions [12]. The virus endemicity level is different from one nation to another. The level is mostly lowered in the Western Europe, the United States, Canada, and some South American and Northern African countries (with an HBsAg chronic carrier rate < 2%); intermediate (i.e., 2–8%) in Eastern Europe, Central Asia, and some Eastern Asian countries; and high (above 8%) in Alaska, Sub-Saharan African countries, and some Asian countries [12, 42]. Infection with HBV is considered among the commonest immunization preventable infections among immigrants [12, 43]. The prevalence of the virus in travelers is associated with the status of the traveler's immunity, the duration of travel, and the level of HBV endemicity in the destination country. More so, there are peculiar populations of travelers that might be of higher risk of HBV acquisition which includes those visiting relatives and friends, the expatriates, dental surgery and medical procedure travelers, and those casual sex engagers [7]. Empirical information posited that travelers seeking urgent, unforeseen medical attention are common which makes travelers at risk of the viral agent [44]. There is paucity of empirical evidence to quantify the risk travelers might also be exposed to HBV through activities that involve tattooing, piercings, and acupuncturing [7]. Coppola et al. [42] reported HBsAg seropositivity of 9.6% among undocumented refugees and immigrants in Southern Italy. The study showed that male sex, SSA origin, low level of schooling, and minor parenteral risks for acquiring HBV infection (acupuncture, tattoo, piercing, or tribal practices) were independently associated with ongoing or past HBV infection [42]. A study in Thailand among international backpackers reported that 25% of its population had engaged in casual sex, while traveling and about half of the population did not often use condom [45]. The risk of HBV infection from sex without protection increase with the number of sex partners, and the incidence of unprotected sex was higher among the singles based on a study carried out on Dutch travelers to tropical and subtropical regions [46]. A study among Australian travelers reported that about half of them had indulged in at least one activity with an HBV risk during their last overseas trip to Southeast or East Asia [47]. Travelers without immunity for the virus traveling to high HBV prevalence countries like Nigeria might be at risk of acquiring the infection due to the many potential accidental and uncontrollable exposures during travel. A Netherlands study reported that 9% of all HBV cases between 1992 and 2003 were travel-related with an estimated incidence of HBV infection of 4.5 per 100,000 travelers [48]. In a study carried out between 1997 and 2007, HBV infection was reported in 51 cases of a cohort of ill travelers presenting to GeoSentinel clinics [49]. The study also found out that male sex and older age are associated with HBV acquisition statistically. Findings among travelers have shown that new sexual partners and unprotected sex are common, especially where there is excessive alcohol intake environment [44, 50, 51]. In countries with high HBV endemicity, the monthly estimated incidence of the infection ranges from 25 per 100,000 for symptomatic infections to 80–420 per 100,000 for all HBV infections in susceptible expatriates residing in such country [52]. Development/aid workers, volunteers, and missionaries pose greater risk of the infection due to extension of travel stay and local community close contact [7]. The prevalence of anti-HBc antibody was

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

#### *Traveler's Infections: Overview of Hepatitis B Virus Infection DOI: http://dx.doi.org/10.5772/intechopen.92174*

*Tourism*

**5. How HBV infection is transmitted**

viral agent to her unborn child [34, 35].

injecting apparatus [31, 32].

Transmission of HBV in travelers is through percutaneous or mucosal exposure to HBV-infected blood or bodily fluids including saliva or semen [30, 31]. There are reports of transmission via sexual contact, contaminated blood and its products, and contaminated medical equipment and through sharing of infected needles and

In SSA, the viral infection, is often disseminated through perinatal and horizontal route, while in the developed regions, most infections occur in adults of younger ages through injecting drug use or high-risk sexual behavior (e.g., bisexuals and homosexuals) [8, 33]. HBV infection is known to be transmitted from the mother to child and it is a thing of worry [34, 35]. Every year, about 25,000 infants are born to HBV-diagnosed mothers in the United States, and approximately 1000 mothers transmit HBV to their infants. This means that about 90% of HBV-infected newborns will eventually develop to chronic infection, and up to 25% of those infected at birth will eventually die prematurely due to HBV-related complications. Therefore, the standard care for pregnant women includes an HBV testing during each pregnancy, to prevent HBV-positive pregnant women from transmitting the

Inadequate infection control in healthcare settings also constitutes to a significant mode of HBV transmission. That is why immigrants from many countries are recommended to be tested for HBV [12]. Transmission by blood transfusion is now rare, whereas before screening of donor blood, it was not uncommon [32]. Cord blood is usually negative for the serological markers of HBV, but occasionally intrauterine infection might happen. Fetal blood sampling might enhance this risk, but amniocentesis does not appear to increase the chances of intrauterine transmission [36]. Infection presumably occurs at or soon after birth. It perhaps occurs through breast (feeding) milk, as it is known to carry the virus. Transmission could occur if there was an in apparent breach in the mucosa of the mouth or during teething [37]. Among adults, high-risk sexual activity is one of the most frequent routes of transmission for HBV [38]. Historically, male homosexual contacts have been associated with a high risk for the viral infection [38]. Sexual transmission accounts

for a majority of the transmission occurring in adult life [38]. More recently, heterosexual transmission is reported to be the most common cause of acute HBV infection in adults [39]. Transmission may also continue to occur in healthcare settings. It is a result of nonadherence to isolation guidelines in a hemodialysis unit, or direct person-person exposure (e.g., surgeon-to-patient or dentist-to-patient) may transmit the virus [40]. Sharing of clothes and bed spaces could pose jeopardy because the virus could be found in saliva, tears, urine, breast milk, and any other body fluid [13]. Other possible means of transmission include an infected parent kissing the cut finger or scraped knee of his child and sharing of personal items of

personal hygiene such as toothbrushes between parents and children [3].

There is insufficient information that depicts predisposing factors to travelers; however, there is scarcity of public reports of HBV infection in travelers, and there is low risk for travelers who are not engaged in high-risk behaviors [7]. The risk of the viral infection might increase in countries/regions that have a 2% prevalence of chronic HBV infection, such as in the African and Western Pacific regions; missionaries, long-term community development workers, and expatriates might be at high risk for the viral agent in such areas [41]. Travelers should take note on how

**6. Epidemiologic studies of HBV infection in travelers**

**304**

the virus is acquired and take precautionary measures to mitigate transmission. The risk of injury due to accident is much higher for travelers than for people in their own environment. These injuries may involve medical attention that will require injections, IVs, or blood transfusions, thereby enhancing the risk of HBV exposure [7]. Older aged travelers, especially those with heart problems, may also require medical treatments that will require the same risks of exposure.

The global prevalence of HBV indicated by the proportion of chronic HBV carriers in the population that is seropositive for the hepatitis B surface antigen (HBsAg) varies strongly between different geographical regions [12]. The virus endemicity level is different from one nation to another. The level is mostly lowered in the Western Europe, the United States, Canada, and some South American and Northern African countries (with an HBsAg chronic carrier rate < 2%); intermediate (i.e., 2–8%) in Eastern Europe, Central Asia, and some Eastern Asian countries; and high (above 8%) in Alaska, Sub-Saharan African countries, and some Asian countries [12, 42]. Infection with HBV is considered among the commonest immunization preventable infections among immigrants [12, 43]. The prevalence of the virus in travelers is associated with the status of the traveler's immunity, the duration of travel, and the level of HBV endemicity in the destination country. More so, there are peculiar populations of travelers that might be of higher risk of HBV acquisition which includes those visiting relatives and friends, the expatriates, dental surgery and medical procedure travelers, and those casual sex engagers [7]. Empirical information posited that travelers seeking urgent, unforeseen medical attention are common which makes travelers at risk of the viral agent [44]. There is paucity of empirical evidence to quantify the risk travelers might also be exposed to HBV through activities that involve tattooing, piercings, and acupuncturing [7].

Coppola et al. [42] reported HBsAg seropositivity of 9.6% among undocumented refugees and immigrants in Southern Italy. The study showed that male sex, SSA origin, low level of schooling, and minor parenteral risks for acquiring HBV infection (acupuncture, tattoo, piercing, or tribal practices) were independently associated with ongoing or past HBV infection [42]. A study in Thailand among international backpackers reported that 25% of its population had engaged in casual sex, while traveling and about half of the population did not often use condom [45]. The risk of HBV infection from sex without protection increase with the number of sex partners, and the incidence of unprotected sex was higher among the singles based on a study carried out on Dutch travelers to tropical and subtropical regions [46]. A study among Australian travelers reported that about half of them had indulged in at least one activity with an HBV risk during their last overseas trip to Southeast or East Asia [47]. Travelers without immunity for the virus traveling to high HBV prevalence countries like Nigeria might be at risk of acquiring the infection due to the many potential accidental and uncontrollable exposures during travel. A Netherlands study reported that 9% of all HBV cases between 1992 and 2003 were travel-related with an estimated incidence of HBV infection of 4.5 per 100,000 travelers [48]. In a study carried out between 1997 and 2007, HBV infection was reported in 51 cases of a cohort of ill travelers presenting to GeoSentinel clinics [49]. The study also found out that male sex and older age are associated with HBV acquisition statistically. Findings among travelers have shown that new sexual partners and unprotected sex are common, especially where there is excessive alcohol intake environment [44, 50, 51]. In countries with high HBV endemicity, the monthly estimated incidence of the infection ranges from 25 per 100,000 for symptomatic infections to 80–420 per 100,000 for all HBV infections in susceptible expatriates residing in such country [52]. Development/aid workers, volunteers, and missionaries pose greater risk of the infection due to extension of travel stay and local community close contact [7]. The prevalence of anti-HBc antibody was

5%, doubling that of the general population in a Swedish expatriate's population. Short duration of travel stay will obviously lower the risk of the infection [53]. Nielsen et al. reported that the incidence per month of HBV infection was 10.2 per 100,000 with 62% of cases traveling for less than 4 weeks [54]. Most research is hinged on travelers becoming sick after travel before testing to occur, so this tends to underestimate the incidence of the viral infection [7, 49].

Many cross-sectional research have find out that travelers have reduced baseline understanding on infections related to travels and put themselves in jeopardy to HBV infection through their actions while in foreign land [47, 55]. Nielsen et al. reported that 5% of short-term and 5% nonimmune travelers were under a great risk of getting infected with HBV via tattooing, injections, and operation activities [44]. About 41% high-risk endeavors were reported among travelers in more than 6 months with most of the endeavors being unintentional and involuntary [44]. In a retrospective study among Australian travelers, 281 (56%) had visited a country with medium to high prevalence of HBV, of whom only 43% had been vaccinated and 162 (33%) undertook activities associated with potential HBV exposure [55]. Medical tourism and transplantation of organs have been identified several times as predictors for the viral agent, which highlights that checking for transmissible infection cannot be guaranteed universally [56, 57]. A study among Australian patients finds out that 2 of 16 who traveled overseas for commercial kidney transplantation developed fulminant hepatitis related to HBV infection and died [58]. Significantly high-incidence rate of HBV infection was reported among patients receiving renal transplantations in India than in Saudi Arabia [59].
