Prevalence of HBs antigen carriers and markers of B virus replication in a population of pregnant women, in France

To assess the risk of perinatal B virus transmission in a population of French and immigrant women, 1,923 women were tested for HBs antigen and serological markers of B virus replication, i. e. HBe antigen and HBV DNA, during the last trimester of their pregnancy. The patients included in this study were French (n = 1,295 (67.3 per cent] and immigrant women (n = 628 (32.7 per cent] attending consultation in four public Parisian suburb hospitals. The immigrant population was composed of natives of the Mediterranean area or Portugal (64 per cent), West Africa (23 per cent), and South-East Asia (13 per cent). Serum HBsAg was tested by conventional radioimmunoassay. When present, HBeAg and antiHBe were tested by radioimmunoassay, and HBV DNA by the hybridization procedure. The overall HBsAg prevalence was 1.56 per cent. This high prevalence was in part explained by the large proportion of immigrants in whom it varied from 0.8 to 7.5 per cent according to their origin. Prevalence was 0.85 per cent in French women, higher than that usually admitted in France. Serological markers of viral replication (HBeAg and/or HBV-DNA) were more often present in the immigrants (4 out of 19) than in the French women (1 out of 11). Discrepancies between HBe status and HBV DNA were present in 4 out of the 30 HBs antigen positive women. Due to the possible high prevalence of HBV carriage in pregnant women, routine antenatal HBs antigen screening should be recommended in France. Such screening, associated with immunoprophylaxis of newborns at risk of contamination, can help in the prevention of perinatal transmission of hepatitis B virus.     

Current evidence on the management of hepatitis B in pregnancy

Hepatitis B virus(HBV) infection is one of the main public health problems across the globe,since almost one third of the world population presents serological markers of contact with the virus. A profound impact on the epidemiology has been exerted by universal vaccination programmes in many countries,nevertheless the infection is still widespread also in its active form. In the areas of high endemicity(prevalence of hepatitis B surface antigen positivity 7%),mother-to-child transmission represents the main modality of infection spread. That makes the correct management of HBV in pregnancy a matter of utmost importance. Furthermore,the infection in pregnancy needs to be carefully assessed and handled not only with respect to the risk of vertical transmission but also with respect to gravid women health. Each therapeutic or preventive choice deserves to be weighed upon attentively. On many aspects evidence is scarce or controversial. This review will highlight the latest insights into the paramount steps in managing HBV in pregnancy,with particular attention to recommendations from recent guidelines and data from up-do-date research syntheses.     

Evidence that anti-HBc but not HBV DNA testing may prevent some HBV transmission by transfusion

Blood donor screening for antibody to hepatitis B core antigen (anti-HBc) implemented in some countries as a surrogate marker for non-A, non-B hepatitis has been superseded by anti-HCV screening. To assess the value of anti-HBc screening for the detection of hepatitis B surface antigen-negative blood donations that might contain infectious HBV, HBV genomic detection and recipient testing were used. Blood donations were screened and confirmed by multiple anti-HBc assays. Donations containing isolated anti-HBc and those with anti-hepatitis B surface antigen (anti-HBs) level < 0.1 IU/ml were tested for the presence of HBV DNA. Recipients of previous donations from the corresponding donors during the previous 5 years were traced and tested for markers of HBV infection. Of 103 869 donations screened, 586 (0.56%) were anti-HBc positive, two of which contained HBsAg, and 413 (0.4%) had protective (>/= 0.1 IU/ml) levels of anti-HBs. Anti-HBs < 0.1 IU/ml was found in 102 of these donations (0.1%) and isolated anti-HBc in 69 (0.07%). No donations with isolated anti-HBc were HBV DNA confirmed positive. Of 278 recipients of previous donations from 171 donors at risk of HBV carriage, 12 had markers of HBV infection. Six recipients had other identified risk factors. An association with blood transfusion was considered probable in two and possible in four recipients. None of the six corresponding donors had detectable HBV DNA 6-40 months after the implicated donation. The frequency of HBV transmission by chronic carriers negative for hepatitis B surface antigen was estimated in this study to be 1 in 52,000 donations (CI 0.3-7.8/100,000) from HBsAg-negative donors. Such HBV infectious donations may not be detected by DNA amplification.     

Seroprevalence of hepatitis B and C infection markers among children and adolescents in the southern Brazilian region

Hepatitis B virus (HBV) and hepatitis C virus (HCV) infections account for a substantial proportion of liver diseases worldwide. The aim of this study was to determine the prevalence of HBV and HCV serological markers among children and adolescents and verify the epidemiology of the HBV infection over than a decade of the introduction of vaccination program. Serologic markers to HBsAg, total anti-HBc and anti-HCV had been tested in 393 samples. The seropositivity for HBsAg was 0.76% and for total anti-HBc was 1.02%. Copositivity between HBsAg and total anti-HBc was verified in 0.76% of the analyzed samples. There was no seropositivity for anti-HCV marker. The seroprevalence of HBV infection markers among children and adolescents in the southern Brazilian region is high compared to that reported in other countries. Preventive measures, such as educational activities in addition to the universal childhood HBV vaccination, should be initiated in order to reduce the morbimortality and the economic burden associated with the disease.     

Vertical transmission of hepatitis B virus during pregnancy and delivery in Denmark

Objective: In Denmark, pregnant women have been screened for hepatitis B virus (HBV) since 2005, and children born to HBV-infected mothers offered hepatitis B immunoglobulin at birth, vaccination against HBV at birth and after 1, 2 and 12 months. The purpose of this study was to determine the risk of vertical HBV transmission in children born to mothers with chronic HBV infection, to investigate the antibody response in the children and to investigate possible maternal predictive risk factors for HBV transmission.

Materials and methods: Through the Danish Database for Hepatitis B and C, we identified 589 HBV-infected women who had given birth to 686 children, of whom 370 children were born to 322 women referred to hospital. 132 (36%) children, born to 109 mothers, were included in the study; 128 children had blood samples tested for HBsAg, anti-HBc (total), anti-HBs and HBV-DNA and four children had saliva samples tested for anti-HBc.

Results: We found vertical HBV transmission in Denmark to be 2.3% [95% CI: 0.5, 6.5], a high proportion of HBsAg-negative children with low levels of anti-HBs (18.4%) and a high proportion (15.2%) with resolved HBV infection. No maternal risk factor was statistically significantly associated with HBV vertical transmission.

Conclusion: In a HBV low prevalence setting as Denmark, despite a national vaccination program, vertical HBV transmission occurred in 2.3% of children born to HBV-infected mothers. In addition, a high proportion of the children had insufficient anti-HBs levels and a high proportion had serological signs of resolved HBV infection.     

Pregnant women's decisions on antenatal HIV screening in Hong Kong

Identification of HIV-infected pregnant women by antenatal screening is crucial to prevent mother-to-child transmission. In Hong Kong, little is known about women's opinions about the screening test. This cross-sectional study examines the decisions of Hong Kong Chinese pregnant women to undergo antenatal HIV screening and the reasons for their choices. Among 191 pregnant women studied, 147 (77.0%) indicated that they would opt for antenatal HIV screening if offered. Of those, 113 (76.9%) would do so for 'the health of their newborns' and 93 (63.3%) for 'their own health'. Fourteen (7.3%) would decline the test, because they have 'one stable sexual partner' (n=9, 64.3%) and believe that 'HIV infection was not their concern' (n=8, 57.1%). Women with a lower educational attainment (adjusted OR=3.77; 95% C.I., 1.12-12.67, p=0.03) were likely to choose antenatal HIV screening. Results of this study are predictive of pregnant women's responses to Hong Kong's newly enacted antenatal HIV screening programme.     

Two decades of universal hepatitis B vaccination in taiwan: impact and implication for future strategies

BACKGROUND & AIMS: Following the world's first successful implementation of a universal hepatitis B virus (HBV) vaccination program for infants in Taiwan 20 years ago, we performed this study to evaluate the long-term protection afforded by HBV vaccination and to rationalize further prevention strategies. METHODS: HBV seromarkers, including hepatitis B surface antigen (HBsAg) and antibodies to HBsAg (anti-HBs) and core antigen (anti-HBc), were studied in 18,779 subjects from neonates to adults below 30 years of age in 2004. The birth cohort effect was evaluated by comparing the results of the same birth cohorts at different ages among this survey and the previous 1984, 1989, 1994, and 1999 surveys. RESULTS: The seropositive rates for HBsAg, anti-HBs, and anti-HBc were 1.2%, 50.5%, and 3.7%, respectively, in those born after the vaccination program (<20 years of age) in 2004. A positive maternal HBsAg status was found in 89% of the HBsAg seropositive subjects born after the vaccination program. The absence of an increase in HBsAg seropositive subjects at different ages in the same birth cohorts born after the vaccination program implied no increased risk of persistent HBV infection with aging. CONCLUSIONS: Universal HBV vaccination provides long-term protection up to 20 years, and a universal booster is not indicated for the primary HBV vaccinees before adulthood. Maternal transmission is the primary reason for vaccine failure and is the challenge that needs to be addressed in future vaccination programs. This may include an appropriate hepatitis B immunoglobulin administration strategy for high-risk infants and involve efforts to minimize noncompliance.     

Why we should routinely screen Asian American adults for hepatitis B: a cross-sectional study of Asians in California

Chronic hepatitis B virus (HBV) infection is a serious liver disease that, if left undiagnosed or without appropriate medical management, is associated with a 25% chance of death from cirrhosis or liver cancer. To study the demographics and prevalence of chronic HBV infection and HBV vaccination in the Asian American population, we provided free HBV serological screening and administered a survey to 3163 Asian American adult volunteers in the San Francisco Bay Area between 2001 and 2006. Of those screened, 8.9% were chronically infected with HBV. Notably, one-half to two-thirds (65.4%) of the chronically infected adults were unaware that they were infected. Of those who were not chronically infected, 44.8% lacked protective antibodies against HBV and were likely susceptible to future infection. Men were twice as likely as women to be chronically infected (12.1% versus 6.4%). Asian Americans born in East Asia, Southeast Asia, or the Pacific Islands were 19.4 times more likely to be chronically infected than those born in the United States. Self-reporting of prior vaccination was unreliable to assess protection against HBV. Among the 12% who reported having been vaccinated, 5.2% were chronically infected, and 20.3% lacked protective antibodies. CONCLUSION: Given the high prevalence of unrecognized chronic HBV infection in the Asian American population, we call for healthcare providers to routinely screen Asian adults for HBV, regardless of their vaccination status. Those who test positive should be provided with culturally appropriate information to prevent disease transmission and proper medical management to reduce their risk of liver disease.     

Screening women of childbearing age for human immunodeficiency virus. A cost-benefit analysis.

In light of the increasing problem of perinatal human immunodeficiency virus (HIV) transmission, the issue of screening women for HIV is receiving considerable attention. We analyzed the costs and benefits of screening women of childbearing age for HIV. The analysis was based on a dynamic model of the HIV epidemic that incorporated disease transmission and progression, behavioral changes, and effects of screening and counseling. We found that the primary benefit of screening programs targeted to women of childbearing age lies not in the prevention of HIV infection in their newborns but in the prevention of infection in their adult contacts. Because of this benefit, screening medium- and high-risk women is likely to be cost-beneficial over a wide range of assumptions about program cost and behavioral changes in response to screening.     

Prevalence of hepatitis-B surface antigen in the pregnant women of Brunei Darussalam

In view of the high incidence of mother-to-child transmission of hepatitis B virus (HBV), routine screening of pregnant at antenatal clinic and vaccination of the newborn has become a common practice throughout the world. The prevalence of HBsAg in pregnant women of Brunei Darussalam was assessed. Of 1,267 pregnant women who attended the antenatal clinic of Suri Seri Begawan Hospital, Kuala Belait, the overall prevalence of HBsAg was 3.2% with significant differences in various ethnic groups (p less than 0.05). Malays, who form the major ethnic group had the lowest rate of 1.9%.     

Hepatitis B virus vaccination and antenatal transmission of HBV markers to neonates

The high prevalence of hepatitis B surface antigen (HBsAg) and hepatitis B e antigen (HBeAg) in pregnant women is considered to be the most important factor contributing to the high carrier rate of HBsAg in some populations. Several factors, including the age at which infection occurs, predispose to the acquisition and frequency of the carrier state. The proportion of infected people who become chronic carriers ranges from about 80 to 95% for babies born to HBsAg/HBeAg-positive mothers. In this study of Indonesian infants receiving only active immunization against HBV, we measured the HBV markers passively acquired from their HBsAg-positive mothers. The relationship of these markers with vaccination response and with HBV infection status was studied longitudinally in the infants. In the exposed neonates from the HBsAg-positive mothers (n=61), the seroconversion rate to hepatitis B surface antibody (HBsAb) positivity was 95% after the first booster vaccination, with a geometric mean titre (GMT) of 2017 IUl-1. After 60 months, the GMT in this group decreased to 50 IUl-1. Four newborns in this group became HBsAg carriers. Of the four vaccination failures, three newborns were HBsAg/HBeAg positive at birth, suggesting that they had been infected in utero. No vaccination strategy (active alone, or passive/active) can prevent this transmission from occurring. One carrier was HBsAg negative at birth and up to month 4 but was HBsAg positive at month 12 and subsequently, suggesting a postnatal infection. Vaccination early in life can, to a large extent, prevent perinatal transmission and hepatitis B virus (HBV) infection later in infancy and childhood. In this study, the protective efficacy of the vaccination was 85% in the subcohort of neonates from HBeAg-positive mothers and 100% in the subcohort of neonates from HBeAg-negative mothers. Lack of maternal antibodies to hepatitis B core antigen (HBcAb) correlated strongly with transmission of HBV infection.     

Distribution Characteristics of Hepatitis B Serological Markers in Hospitalized Children and Adolescents in Zhejiang, China between 2006 and 2010

Background/Aims

To investigate serological patterns of hepatitis B based on electrochemiluminescent immunoassays and the distribution characteristics of these patterns in hospitalized children and adolescents in Zhejiang, China between 2006 and 2010.

Methods

Five serological markers, including hepatitis B surface antigen (HBsAg), hepatitis B e antigen (HBeAg), antibody to hepatitis B surface antigen (anti-HBs), antibody to hepatitis B e antigen (anti-HBe), and antibody to hepatitis B c antigen (anti-HBc), were chosen as a routine panel to monitor hepatitis B virus (HBV) infection and vaccination efficacy. A total of 33,187 children (21,187 boys and 12,000 girls) were selected using the following exclusion criteria: a previous diagnosis of hepatitis, age >16 years or an address outside of Zhejiang.

Results

The average HBV vaccination coverage rates among 20,766 boys and 11,782 girls were 98.62% and 98.68%, respectively. Seventeen serological patterns of hepatitis B were found, and the dominant pattern was ''anti-HBs (+) alone'' (62.03%) followed by ''negative pattern'' (23.46%). The rates of the other 15 patterns ranged from 8.14% to 0.003%. Of 236 HBsAg-positive patients, the overall rate of seropositivity was 0.71%. The anti-HBs levels were grouped into 3 ranges (10-100 mIU/mL, 100-1,000 mIU/mL, and >1,000 mIU/mL) for all anti-HBs-positive children (36.08%, 43.43%, and 20.49%, respectively).

Conclusions

A low HBsAg carrier rate and a relatively high anti-HBs positive rate are present in hospitalized children and adolescents in Zhejiang. The distribution of serological patterns is associated with age but is mostly independent of gender.     

Hepatitis B virus prevalence and vaccination response in health care workers and students at the Federal University of Bahia, Brazil

Background and rationale for the study. Hepatitis B (HB) is one of the most prevalent occupational infections in health attendance environments. According to the Brazil Ministry of Health, health professionals must be vaccinated against the hepatitis B virus (HBV) and provide laboratory proof of immunization. Aims. To evaluate the seroprevalence of HBV infection and to analyze the response to vaccine by measuring serum antibodies against HBV surface antigen (anti-HBs) levels in a sample of students and health professionals at the Federal University of Bahia.Results. As part of this cross-sectional study, a campaign against occupational HB was launched in 2007 and vaccination and blood samples were collected for analysis of the following serological markers: HBV surface antigen (HBsAg) and anti-HBs (measured by enzyme-linked immunoassay) and total antibodies against HBV core antigen (anti-HBc). The study sample comprised 766 people. Global seropositivity for HBV was 1.7%: 0.5% in the students and 8.8% in the professionals. In a group of volunteers, a serological profile compatible with postvaccine immunity was shown by 95% of volunteers with proof of vaccination and by 81.8% of volunteers without proof of vaccination. Conclusions. In conclusion, this study shows that it is important to promote vaccination campaigns and improve knowledge and awareness about HB among health care workers and higher education students.     

Eight years of hepatitis B vaccination in Colombia with a recombinant vaccine: factors influencing hepatitis B virus infection and effectiveness.

OBJECTIVE: To evaluate the effectiveness of a recombinant hepatitis B vaccine used in endemic areas of Colombia, as well as risk factors associated with hepatitis B virus (HBV) infection and carriage after vaccine introduction. METHODS: A cross-sectional study was carried out in urban and rural areas of the Colombian Amazon, a highly endemic area for hepatitis B infection. Children under 12 years of age and their mothers were selected for the study using one-stage cluster sampling (N=2145) and were examined for HBV serological markers and antibodies against surface antigen (anti-HBs). RESULTS: There has been a reduction of 60-75% in the prevalence of HBV infection and hepatitis B surface antigen (HBsAg) carriage since HBV vaccination was introduced. Receiving the first dose of HBV vaccine at more than two months after birth was one of the factors associated with HBV carrier status. Maternal HBV infection was also associated with infection in the child. CONCLUSIONS: The recombinant Cuban hepatitis B vaccine has contributed to the reduction of the infection in this highly endemic area, though further efforts are required to improve timely vaccination for children at high risk.     

Feasibility of voluntary counselling and testing services for HIV among pregnant women presenting in labour in Pune, India

Factors affecting the eligibility and acceptability of voluntary counselling and rapid HIV testing (VCT) were examined among pregnant women presenting in labour in Pune, India. Of the 6702 total women appearing at the delivery room from April 2001 to March 2002, 4638 (69%) were admitted for normal delivery. The remaining women presented with obstetrical complications, delivered immediately or were detected to be in false labour. Overall, 2818 (61%) of the admitted women had been previously tested for HIV during their pregnancy. If previously seen in the hospital's affiliated antenatal clinic, the likelihood of being previously tested was 89%, in contrast to 27% of women having prenatal care elsewhere. Of the admitted women, 3436 (74.3%) were assessed for their eligibility for rapid HIV VCT in the delivery room. Only 1322 (38%) of these women were found to be in early labour and without severe pain or complications, and therefore eligible for rapid HIV screening in the delivery room (DR). Of those 1322 eligible women, only 582 (44%) consented and were tested for HIV, of whom nine (1.6%) were found to be HIV-infected. Of the 1674 women arriving in the DR with no evidence of previous HIV testing, through this DR screening programme, we identified four women with HIV who could now benefit from treatment with ART. Given the high rates of HIV testing in the antenatal clinic at this site and the challenges inherent to conducting DR screening, alternatives such as post-partum testing should be considered to help reduce maternal to infant transmission in this population.     

Maternal and Neonatal Outcomes of SARS-CoV-2 Infection in a Cohort of Pregnant Women with Comorbid Disorders

There are some reports and case series addressing Coronavirus Disease 2019 (COVID-19) infections during pregnancy in upper income countries, but there are few data on pregnant women with comorbid conditions in low and middle income Countries. This study evaluated the proportion and the maternal and neonatal outcomes associated with SARS-CoV-2 infection among pregnant women with comorbidities. Participants were recruited consecutively in order of admission to a maternity for pregnant women with comorbidities. Sociodemographic, clinical, and laboratory data were prospectively collected during hospitalization. Pregnant women were screened at entry: nasopharyngeal swabs were tested by RT-PCR; serum samples were tested for IgG antibodies against spike protein by ELISA. From April to June 2020, 115 eligible women were included in the study. The proportion of SARS-CoV-2 infection was 28.7%. The rate of obesity was 60.9%, vascular hypertension 40.0%, and HIV 21.7%. The most common clinical presentations were ageusia (21.2%), anosmia (18.2%), and fever (18.2%). Prematurity was higher among mothers who had a SARS-CoV-2 infection based on RT-PCR. There were two cases of fetal demise. We found a high proportion of COVID-19 among pregnant women with comorbidities. This underscores the importance of antenatal care during the pandemic to implement universal SARS-CoV-2 screening, precautionary measures, and the rollout of vaccination programs for pregnant women.     

Transmission dynamics and epidemiological characteristics of SARS-CoV-2 Delta variant infections in Guangdong,China, May to June 2021

BackgroundThe Delta variant of SARS-CoV-2 had become predominant globally by November 2021.AimWe evaluated transmission dynamics and epidemiological characteristics of the Delta variant in an outbreak in southern China.MethodsData on confirmed COVID-19 cases and their close contacts were retrospectively collected from the outbreak that occurred in Guangdong, China in May and June 2021. Key epidemiological parameters, temporal trend of viral loads and secondary attack rates were estimated. We also evaluated the association of vaccination with viral load and transmission.ResultsWe identified 167 patients infected with the Delta variant in the Guangdong outbreak. Mean estimates of latent and incubation period were 3.9 days and 5.8 days, respectively. Relatively higher viral load was observed in infections with Delta than in infections with wild-type SARS-CoV-2. Secondary attack rate among close contacts of cases with Delta was 1.4%, and 73.1% (95% credible interval (CrI): 32.9–91.4) of the transmissions occurred before onset. Index cases without vaccination (adjusted odds ratio (aOR): 2.84; 95% CI: 1.19–8.45) or with an incomplete vaccination series (aOR: 6.02; 95% CI: 2.45–18.16) were more likely to transmit infection to their contacts than those who had received the complete primary vaccination series.DiscussionPatients infected with the Delta variant had more rapid symptom onset compared with the wild type. The time-varying serial interval should be accounted for in estimation of reproduction numbers. The higher viral load and higher risk of pre-symptomatic transmission indicated the challenges in control of infections with the Delta variant.     

Exposure to hepatitis B and C of tattooists in Victoria in 1984

SUMMARY. Although tattooing is recognized as a risk factor for transmission of hepatitis C, the efficiency with which transmission occurs is unknown. Sera stored from a serosurvey of tattooists undertaken in 1984 to test for human immunodeficiency virus (HIV) provided the opportunity to determine the prevalence of serological markers of hepatitis B virus (HBV) and hepatitis C virus (HCV) in tattooists at that time. The stored sera had been obtained from five unregistered and 36 of 37 (97%) of the registered tattooists operating in 1984. Serological status for hepatitis B (hepatitis B surface antigen (HBsAg), antibody to hepatitis B surface antigen (HBsAb) and antibody to hepatitis B core antigen (HBcAb) in standard assays) or hepatitis C (HCV antibody reactivity in second and third generation tests, confirmed by recombinant immunoblot assay) was determined. No sera was HIV positive or HBsAg positive. Of 35 specimens tested for HCV specific antibody, only two (5.6%) were positive despite markers of HBV in 48.6% of the same sera. As acute HBV infection was common amongst tattooists prior to 1984, it is clear that hepatitis B vaccination would be of benefit to this group. Despite frequent needlestick injuries reported by tattooists at the time, the low seroprevalence of HCV in this group suggests that HCV may not be transmitted efficiently by intradermal inoculation using solid-bore tattooing needles.     

Hepatitis B virus infection in 6,130 unvaccinated Korean-Americans surveyed between 1988 and 1990

OBJECTIVES: During the past decades, the influx of immigrants from hepatitis B virus (HBV) endemic regions has brought significant changes in the prevalence of HBV-associated liver diseases and hepatocellular carcinoma (HCC) in the United States. Our program, which was intended to identify those in need of hepatitis B vaccination, helped us to learn of the natural history of HBV infection in Korean Americans. METHODS: Between November of 1988 and May 1990, we screened 6,130 Korean Americans in the eastern United States for HBV infection. RESULTS: The overall hepatitis B surface antigen (HBsAg) (+) rate was 6.1%, with 8.0% for males and 4.4% for females. The carrier rate peaked in subjects between the ages of 21 and 40 yr. The HBsAg (+) rate for 452 U.S.-born children was lower (2.7%) than that of 623 Korean-born (5.5%). None received hepatitis B immune-globulin or HBV vaccination. The vertical transmission rate was 30.3% in children born to HBsAg (+) mothers and 100% in those born to hepatitis B e antigen (HBeAg) positive mothers. In contrast, the paternal transmission rate was low; 10.3% in children with HBsAg (+) fathers and 19.2% in those with HBeAg (+) fathers. Another significant observation was the unexpected finding of ongoing liver diseases in incidentally identified carriers. Evaluation of 139 asymptomatic adult carriers revealed that 42% had elevated liver enzymes and 11% had already developed liver cirrhosis. CONCLUSION: These findings strongly suggest the need for active HBV screening of immigrants from endemic regions and, most importantly, the need for careful monitoring of the carriers.