Augusto L. Lingao

Nucleotide sequence of a hepatitis B virus genome of subtype adw isolated from a Philippine: Comparison with the reported three genomes of the same subtype

The complete nucleotide sequence was determined for a hepatitis B virus genome of subtype adw (pFDW294) isolated and cloned from the plasma sample of a Philippino. The genome was 3221 base‐pair long with a point mutation at the 1376th nucleotide that affected the coding capacity of the P and X genes. There was a wide range of sequence divergence among pFDW294 and the reported three genomes of the same subtype (1.1–9.9%), occurring more often in the pre‐S region and the S gene than in the pre‐C region and the C gene.

Mother to child transmission of hepatitis B virus in the Philippines

SummaryA follow-up study of mother to infant transmission of hepatitis B virus was conducted in the Philippines between 1981 and 1983. The prevalence of HBsAg among 527 mothers was 8.5%. Overall, seven out of 17 (41.2%) infants born to HBsAg carrier mothers became HBsAg positive within the first 12 months of life. The risk of becoming HBsAg positive was about 20 times higher for infants born to HBsAg positive mothers than for infants born to HBsAg negative mothers (OR=18.9, 95% Ci=2.0−86.6). The risk was even higher if the mother was a carrier of both HBsAg und HBeAg (OR=91.0, 95% Ci=49.2−164.8). However, the risk of transmission was very low if the mother was an HBsAg carrier and anti-HBe positive. It was estimated that mother to infant transmission accounts for about one third of HBsAg positivity at one year of age. The implications of these findings in the planning of vaccination campaigns to prevent HBV infections are discussed.ZusammenfassungIn den Philippinen wurde zwischen 1981 und 1983 eine Verlaufsstudie zur Mutter-Kind-Übertragung des Hepatitis-B-Virus durchgeführt. Bei 527 Müttern fand sich eine HBsAg-Prävalenz von 8,5%. Sieben von 17 Neugeborenen (41,2%) der HBsAg-Carrier-Mütter wurden im Ablauf der ersten 12 Lebensmonate HBsAg-positiv. Bei Kindern HBsAg-positiver Mütter war das Risiko einer HBsAg-Serokonversion 20mal höher als bei Kindern HBsAg-negativer Mütter (OR=18,9; 95%; Ci=2,0−86,6). Bei Müttern, die nicht nur HBsAg, sondern auch HBeAg-Carrier waren, bestand ein noch größeres Risiko für das Kind, HBsAg-positiv zu werden (OR=91,0; 95%; Ci=49,2−164,8). Bei Müttern, die HBsAg-Carrier, aber anti-HBe-positiv waren, bestand nur ein sehr geringes Übertragungsrisiko. Schätzungsweise sind ein Drittel der Fälle von HBsAg-Positivität bei einjährigen Kindern auf Mutter-Kind-Übertragung zurückzuführen. Die Bedeutung dieser Daten für die Planung von Impfaktionen zur Prävention von HBV-Infektionen wird diskutiert.

Sensitivity and specificity of capillary blood HBsAg as a surrogate marker for HBeAg in pregnant women

Infants at high risk of acquiring hepatitis B virus (HBV) infection from their hepatitis B e antigen (HBeAg)‐positive mothers are prime targets for early HBV immunization. The usefulness of fingerprick blood of pregnant women as a surrogate marker to identify infants who would need immunization soon after birth was evaluated. Using HBeAg from venous blood as the standard, the detection of hepatitis B surface antigen (HBsAg) by reverse passive haemagglutination in capillary blood yielded an overall sensitivity of 97% and a specificity of 96% for detecting HBeAg at a cutoff titre of 22.5. Pregnant women with a capillary HBsAg titre of 22.5 or greater are 24 times more likely to infect their babies, while the chances of transmitting HBV infection with a titre lower than the cutoff point are almost nil. When the cost of HBV vaccine eventually comes down to levels suitable for public health use, a cutoff titre of 22.5 is suggested in order to identify infants who should be vaccinated soon after birth.