Heterogeneity of hepatitis B transmission in Tunisia: risk factors for infection and chronic carriage before the introduction of a universal vaccine program.
A population-based sero-epidemiological study enrolled 9486 volunteers in two governorates, Béja in the north and Tataouine in the south of Tunisia, in order to assess the magnitude of HBV transmission heterogeneity between the north and the south and within the same governorate, as well as the risk factors associated with infection and chronic carriage.


RESULTS
The overall prevalence of anti-HBc, HBsAg and chronic carriage was 28.5, 5.3 and 2.9%, respectively. Significant differences were observed between the two governorates according to anti-HBc (32.1% in Béja and 27.8% in Tataouine; p=0.005) and HBsAg prevalence (4.2% in Béja and 5.6% in Tataouine; p=0.001). Significant differences were noticed between districts revealing important heterogeneity in HBV transmission within the same governorate (HBsAg ranged from 12 to <2% within the same governorate). At the individual level, the presence of a family member infected with HBV, scarification practices, needle practices in the Primary Care Center and gender (male) significantly increased the risk of anti-Hbc, HBsAg positivity and chronic carriage of infection while existence of sanitation in the house was found to be protective. The basic reproductive number and the force of infection confirmed the heterogeneity of transmission. Horizontal transmission within the family explains hyperendemic clusters in Tunisia.
Laboratory of Medical Epidemiology, Pasteur Institute Tunis, 13 place Pasteur, BP 74, 1003 Tunis-Belvedere, Tunisia. nissaf.benalaya@pasteur.rns.tn
Nissaf
N
Ben-Alaya-Bouafif
Olfa
O
Bahri
Sadok
S
Chlif
Jihène
J
Bettaieb
Amine
A
Toumi
Hamida Nabil
HN
Bel Haj
Amor
A
Zâatour
Adel
A
Gharbi
Koussay
K
Dellagi
Hinda
H
Triki
Afif
A
Ben Salah
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D050936:Basic Reproduction Number; D002353:Carrier State / Q000453:epidemiology* / Q000517:prevention & control / Q000635:transmission / Q000821:virology*; D002675:Child, Preschool; D005260:Female; D006509:Hepatitis B / Q000453:epidemiology* / Q000517:prevention & control / Q000635:transmission / Q000821:virology*; D006510:Hepatitis B Antibodies / Q000097:blood; D006514:Hepatitis B Surface Antigens / Q000097:blood; D017325:Hepatitis B Vaccines / Q000276:immunology*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D016036:Seroepidemiologic Studies; D014416:Tunisia / Q000453:epidemiology; D055815:Young Adult
D006510:Hepatitis B Antibodies; D006514:Hepatitis B Surface Antigens; D017325:Hepatitis B Vaccines