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Biomedical subjects

P E Hewitt

Publications and source records attributed to P E Hewitt.

At least 19 recordsLinked to original sources
PubMed1999

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B core antigen (anti-HBc) implemented in some countries as a surrogate marker for non-A, non-B hepatitis has been superseded by anti-HCV screening.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.

Amino Acid Sequence↗
PubMed1998

Fatal Clostridium perfringens sepsis from a pooled platelet transfusion.

A male patient with acute myeloid leukaemia received a pooled platelet preparation prepared by Optipress system on the last day of its shelf life. The patient collapsed after two-thirds of the contents had been transfused. Clostridium perfringens was isolated from the platelet bag within 18 h of the acute event. Metronidazole, gentamicin and Clostridium antiserum were then administered in addition to the broad spectrum antibiotics started previously. However, the patient died 4 days after the platelets were transfused. The cause of death was given as cardiovascular shock, entirely compatible with an overwhelming bacteraemic and septic episode. A coroner's verdict of accidental death due to transfusion of a contaminated unit of platelets was recorded. On subsequent investigation Cl. perfringens type A serotype PS68,PS80 (identical to that found in the platelet bag) was cultured from the venepuncture site of the arm of one of the donors who contributed towards the platelet pool. The donor had two young children and frequently changed nappies. Faecal contamination of the venepuncture site was the suspected source for the transmission of Cl. perfringens, an organism commonly found in the soil and intestinal tract of humans. This case dramatically highlights the consequences of transfusing a bacterially contaminated unit. It is vital that such incidents are investigated and reported so that the extent of transfusion-associated bacterial transmission can be monitored and preventative measures taken if possible.

Acute Disease↗
PubMed1998

Review of counselling in a transfusion service: the London (UK) experience.

Donor (and recipient) counselling within the Transfusion Service in the UK has grown in volume and complexity over the last 10 years. The addition of new tests for donated blood and the growth of bone marrow transplantation have increased the demands on counselling staff. New initiatives, such as the HCV look-back programme, have required an extension of the skills and knowledge of staff involved in counselling.

Blood Donors↗
PubMed1997

Does anti-HBc reactivity reflect 'lifestyle' risk in north London blood donors?

BACKGROUND AND OBJECTIVES: To determine whether antibody to hepatitis B core (anti-HBc) reactivity, as a marker of hepatitis B virus infection, reflects a 'lifestyle' risk in donors in North London, we have obtained detailed histories from donors with various manifestations of HBV infection. MATERIALS AND METHODS: Interviews based on a standardised questionnaire were conducted with 70 donors confirmed to be anti-HBc reactive. RESULTS: Comparison with controls (known to be anti-HBc-negative) and donors reactive for anti-hepatitis-C virus showed that current donor strategies are effective; in our area, reactivity for anti-HBc is not associated with a lifestyle risk for those donors who are unreactive in current mandatory screening tests. CONCLUSIONS: Blood from donors positive for both anti-HBc and anti-HBs should be considered suitable for transfusion purposes. This is consistent with the practice of accepting blood from naturally immune donors for preparation of hepatitis B immunoglobulin.

Antibodies, Viral↗
PubMed1997

Evaluation of a malaria antibody ELISA and its value in reducing potential wastage of red cell donations from blood donors exposed to malaria, with a note on a case of transfusion-transmitted malaria.

BACKGROUND AND OBJECTIVES: Blood donations are often wasted for lack of a satisfactory procedure to evaluate donors potentially exposed to malaria. MATERIALS AND METHODS: We evaluated a commercial ELISA for the detection of antibodies to malaria and compared it with an immunofluorescent antibody test (IFAT). RESULTS: When 5,311 sera from routine non-exposed donors were tested, 24 (0.45%) were positive by the ELISA, using a Plasmodium falciparum antigen. Seventeen were subjected to confirmatory testing but none were positive by IFAT. Of 1,000 donors potentially exposed in endemic areas 15 (1.5%) were repeatably reactive by ELISA. 10 of these were tested by IFAT and 2 were positive. When 150 patients attending the Hospital for Tropical Diseases in London with acute malaria were tested, 73% of those infected with P. falciparum were repeatably reactive for malarial antibodies by ELISA and 56% with Plasmodium vivax. Of 88 stored clinical sera tested by both IFAT and ELISA 56 were positive by IFAT and of these 52 (93 degrees/0) were positive by ELISA. CONCLUSION: The ELISA is sufficiently sensitive and specific to screen at-risk donors. Its use could safely retrieve 40,000 red cell units currently discarded each year in Great Britain.

Animals↗
PubMed1996

Yersinia enterocolitica transmission from a red cell unit 34 days old.

In 1993 the North London Blood Transfusion Centre received its first report of Yersinia enterocolitica transmission from a unit of red cells supplied to a local hospital. The recipient was a 23-year-old male who was neutropenic following a third cycle of chemotherapy for treatment of acute myeloblastic leukaemia (FAB type M6) and received a 34-day-old red cell unit. During transfusion the patient developed septicaemia and endotoxin-mediated shock. The transfusion was stopped immediately and broad spectrum antibiotics administered immediately on suspicion of bacteraemia from the transfused unit. This prompt action undoubtedly prevented a fatal outcome. Y. enterocolitica was isolated from the blood bag. Antibody was also detected in the bag and in a sample taken from the donor 39 days post-donation. Antibody to serotype 03 was identified, the commonest serotype reported in transfusion-transmitted Y. enterocolitica. The donor reported no gastrointestinal upset or illness prior to donation. This transfusion reaction might not have occurred had the red cells been transfused earlier in their storage period, but would not have been prevented by the exclusion of donors with a history of gastrointestinal illness as the donor was asymptomatic. Nor would it have been prevented by inspecting the blood for a change in colour, as no such change was observed. Y. enterocolitica is a significant problem in transfusion medicine and transmission is generally associated with a high mortality rate. Hospitals should be urged to investigate bacteriologically all appropriate transfusion reactions so that the true extent of the problem in the United Kingdom can be assessed.

Adult↗
PubMed1995

Confidential unit exclusion: the North London Blood Transfusion Centre's experience.

A 'Confidential AIDS Questionnaire' has been used at North London Blood Transfusion Centre (NLBTC) donor sessions since July, 1985. The aim of the questionnaire is to encourage self-exclusion by those donors whose behaviour puts them at risk of HIV infection. In a situation where such individuals cannot avoid donating they can indicate, in confidence, that their blood should not be used for transfusion. Since the introduction of this procedure, an average of 10 donors per month, who admitted relevant risk behaviour, have been permanently excluded and a number of prospective donors have excluded themselves when faced with the questionnaire. We have found the questionnaire to be well accepted by donors. It is a useful adjunct to routine donor selection and microbiological testing of donations in our efforts to minimize transfusion-transmitted infection.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Visceral leishmaniasis after cardiac surgery.

An English child developed visceral leishmaniasis (kala-azar) after cardiac surgery. Neither he nor his mother had ever been out of the UK, and his disease was probably transmitted by blood transfusion. Kala-azar should be considered in patients with unexplained fever and hepatosplenomegaly, even if there is no history of foreign travel.

Blood Transfusion↗