The Outbreak of Hepatitis A in Italian Patients with Hemophilia: Facts and Fancies

Hepatitis A immunization in HIV-infected haemophilic patients

Forty-seven HIV-infected haemophilic patients were entered into a hepatitis A vaccination programme. 10 patients (21%) were lgG seropositive for hepatitis A consistent with past exposure. Of the 37 patients offered vaccination, one refused and 31 completed the vaccination course, 17/13 (55%) seroconverted, nine after the second and eight after the third injection, and 14 patients failed to seroconvert. The CD4 lymphocyte counts immediately prior to vaccination were significantly higher in the patients who developed immunity compared to the nonresponders (median CD4 count in the immune group 380 × 10(6) /1 (range 170-1290), median CD4 count in nonimmune group 110 × 10(6) /1 (range 10-590), P== 0.003). No patient with a CD4 count < 170 × 10(6) /1 seroconverted and five patients with well-preserved CD4 counts also failed to seroconvert. We conclude that HIV-infected haemophilic patients, especially those with more advanced disease, have an impaired response to hepatitis A vaccination. Due to the likely failure of response in patients with CD4 counts < 150 × 10(6) /1, it is reasonable not to include these patients in a hepatitis A vaccination programme.

Pathogen inactivation and removal methods for plasma-derived clotting factor concentrates

Pathogen safety is crucial for plasma-derived clotting factor concentrates used in the treatment of bleeding disorders. Plasma, the starting material for these products, is collected by plasmapheresis (source plasma) or derived from whole blood donations (recovered plasma). The primary measures regarding pathogen safety are selection of healthy donors donating in centers with appropriate epidemiologic data for the main blood-transmissible viruses, screening donations for the absence of relevant infectious blood-borne viruses, and release of plasma pools for further processing only if they are nonreactive for serologic markers and nucleic acids for these viruses. Despite this testing, pathogen inactivation and/or removal during the manufacturing process of plasma-derived clotting factor concentrates is required to ensure prevention of transmission of infectious agents. Historically, hepatitis viruses and human immunodeficiency virus have posed the greatest threat to patients receiving plasma-derived therapy for treatment of hemophilia or von Willebrand disease. Over the past 30 years, dedicated virus inactivation and removal steps have been integrated into factor concentrate production processes, essentially eliminating transmission of these viruses. Manufacturing steps used in the purification of factor concentrates have also proved to be successful in reducing potential prion infectivity. In this review, current techniques for inactivation and removal of pathogens from factor concentrates are discussed. Ideally, production processes should involve a combination of complementary steps for pathogen inactivation and/or removal to ensure product safety. Finally, potential batch-to-batch contamination is avoided by stringent cleaning and sanitization methods as part of the manufacturing process.

Current update of pediatric hepatitis vaccine use

Vaccines are now available for the prevention of hepatitis A and hepatitis B. In this article, biologics are reviewed with special attention to their use in the pediatric patient. Special attention is paid to issues that developed in 1999. For hepatitis A vaccine, it is the change in US recommendations regarding increased use in higher-risk US locations. For hepatitis B vaccine, it is the concern about toxicity, real or imagined.

An international collaborative study on the detection of an HIV-1 genotype B field isolate by nucleic acid amplification techniques

An international collaborative study to assess inter-laboratory variation in the sensitivity of gene amplification assays for the detection of HIV-1 RNA sequences was conducted using a panel of eight duplicate dilutions of an HIV-1 genotype B clinical isolate and negative control samples. Twenty-five laboratories participated in the study and used a variety of in-house assays and commercial assay systems. With few exceptions, the assays were more sensitive than a p24 antigen assay. Overall, the PCR-based Amplicor Monitor assay was the most sensitive and gave the highest mean copy number for any one sample. Some of the in-house assays gave results comparable with the Monitor assay whilst the NASBA and bDNA assays appeared to be less sensitive. As a result of this study, an HIV-1 Working Reagent for the standardisation of nucleic acid amplification assays was developed and assessed in a subsequent study. Similar differences in sensitivity between the different assay systems was observed. The discrepancies in viral copy number obtained using the Working Reagent highlights the need for an International Standard against which all Working Reagents may be calibrated.

Human recombinant DNA-derived antihaemophilic factor (factor VIII) in the treatment of haemophilia A: conclusions of a 5-year study of home therapy. The KOGENATE Study Group

Fifty-eight previously treated haemophilic subjects were treated exclusively with the recombinant FVIII (rFVIII-KOGENATE) produced by Bayer Corporation (Berkeley, CA) in an international multicentre prospective study of more than 5 years duration. Fifty-four of the 58 had severe haemophilia (< 2% FVIII) and four had moderate haemophilia (2-5% FVIII); 23/58 (40%) were seropositive for HIV, while 35/58 (60%) were HIV seronegative. Patients were monitored for safety and efficacy over a median period of 4.7 years (range 0.9-5.9 years) and received 17 922 infusions totalling 25.7 million units of rFVIII. Of 7107 bleeding episodes reported in home diaries, 5831 (82%) required only one treatment with rVIII. Twenty-five invasive surgical procedures in 17 patients, including eight joint replacements, were successfully accomplished and 13 serious bleeding episodes in eight patients were successfully treated. FVIII recovery performed on 885 occasions using 39 different lots of rFVIII showed mean incremental recovery of 2.48% IU-1 kg-1 (+/- 0.64). Adverse events were associated with 42 infusions (0.2%); none caused discontinuation of therapy. Immunological parameters remained stable in HIV-seronegative subjects treated with rFVIII; a small decrease in CD4 counts was noted in HIV-seropositive individuals (mean - 37.2 cells mm-3 yr-1). No de novo formation of inhibitors to FVIII was noted; and no clinical allergic reactions occurred to murine or hamster proteins. These conclusions from the longest monitored safety study ever performed for a haemophilia treatment product (with more than 5 years of observation) confirm previous interim study reports that rFVIII is well tolerated over the long-term, has biological activity comparable to that of plasma-derived FVIII, and is safe and efficacious for the treatment of haemophilia A.

Transfusion-transmitted diseases: risks, prevention and perspectives

During the past decades major improvements in blood safety have been achieved, both in developed and developing countries. The introduction of donor counseling and screening for different pathogens has made blood a very safe product, especially in developed countries. However, even in these countries, there is still a residual risk for the transmission of several pathogens. For viruses such as the human immunodeficiency virus (HIV), and the hepatitis viruses B and C, this is due mainly to window-period donations. Furthermore, the threat of newly emerging pathogens which can affect blood safety is always present. For example, the implications of the agent causing new variant Creutzfeld-Jakob disease for transfusion practice are not yet clear. Finally, there are several pathogens, e.g. CMV and parvo B19, which are common in the general donor population, and might pose a serious threat in selected groups of immunosuppressed patients. In the future, further improvements in blood safety are expected from the introduction of polymerase chain reaction for testing and from the implementation of photochemical decontamination for cellular blood products. The situation in transfusion medicine in the developing world is much less favorable, due mainly to a higher incidence and prevalence of infectious diseases.

Transfusion-transmitted disease

Many patients with haemophilia are infected with viruses, due to treatment with blood products--particularly from large pool clotting factor concentrates before 1985. AIDS in haemophilic patients was first described in 1982 and it has significantly reduced the life expectancy of these patients. Although no new sero-conversions have occurred since 1986, management of HIV in haemophilia remains a clinical challenge. Transfusion-associated hepatitis was recognized in 1943, and it is now an important complication of haemophilia treatment. Vaccination against HAV is recommended. Intensively-treated older haemophilic patients usually have serological evidence of HBV infection. HBV transmission has been stopped, but hepatitis B vaccination is still practised, because HDV requires HBV for propagation. Many patients are infected with HCV: before 1985 almost all patients who received clotting factor concentrate developed non-A, non-B hepatitis, now recognized as HCV. Treatment strategies are being developed for HCV in haemophilic patients. Parvo virus can be transmitted by clotting factor concentrate; it is very resistant to sterilization processes, transmission causing severe illness even in immuno-competent individuals. New blood-borne viruses responsible for sero-negative hepatitis include: GBV-A, B and C, and HGV. Although there is no link between CJD and haemophilia, there is concern about possible blood product transmission.

Update on viral hepatitis in children

Recent discovery of the two major agents responsible for non-A, non-B hepatitis has led to rapid progress in the diagnosis and prevention of viral hepatitis. Newly implemented vaccine strategies against hepatitis A and hepatitis B are protecting children from infection, and new immunomodulatory therapy with interferon-alpha is being used to eradicate disease in patients chronically infected with hepatitis virus B or C.