Janet Mortimer

REACTIONS AND ANTIBODY RESPONSES TO REINFORCING DOSES OF ADSORBED AND PLAIN TETANUS VACCINES

In children aged 15--16 years receiving routine reinforcement tetanus immunisation, adsorbed vaccine caused more severe and more frequent local reactions than did plain formol toxoid, and a higher incidence of pyrexia. The incidence of swelling and erythema at the inoculation site increased with serum antitoxin titre at the time of inoculation, whereas pain and tenderness were related to the presence of the aluminium hydroxide adjuvant. Both vaccines gave satisfactory antibody responses over a 5-month observation period; plain formol toxoid induced higher mean titres than did the adsorbed vaccine. It is recommended that plain and not adsorbed vaccine be used when reinforcement of immunity to tetanus alone is desired.

WHICH ANTI-HTLV III/LAV ASSAYS FOR SCREENING AND CONFIRMATORY TESTING?

In preparation for routine anti-HTLV-III/LAV testing in the UK five commercial assays (A-E) were evaluated using 360 sera selected on clinical and epidemiological grounds. These comprised 220 specimens from blood donors, 83 specimens from patients in high-risk groups, and 57 specimens with features likely to produce false-positive results. Probably erroneous positive results arose from assay A in all three categories and assay B in the second and third categories. These reactions were much more common after specimens had been heated to 56 degrees C for 30 min. Except that an anti-HLA DR4,B5-containing serum was repeatedly positive by C, assays C, D, and E apparently did not give rise to false-positive results. Results by these three assays were also highly reproducible. In tests on serum dilutions the highest titres were obtained by assays A and D, but assays C and E discriminated most clearly between anti-HTLV-III/LAV positive and negative sera. These two assays were rapid and convenient and seemed particularly suitable for testing blood donations. Assay D was almost comparable with them in performance but more difficult to use. The commercial assays C, D and E, an antibody capture assay, and a simple immunofluorescence test could be the basis for a methodologically diverse national system of primary and confirmatory testing for anti-HTLV-III/LAV.

SYMPTOMS AFTER PRIMARY IMMUNISATION WITH DTP AND WITH DT VACCINE

Symptoms after routine primary immunisation of 6004 infants with diphtheria/tetanus/pertussis (DTP) vaccine and 4024 infants with diphtheria/tetanus (DT) vaccine have been compared. After each dose, crying, screaming, and feverishness were more frequent with adsorbed DTP than adsorbed DT, but the difference was small. Attacks of high-pitched screaming, episodes of pallor or cyanosis with limpness, convulsions, and local reactions occurred with similar frequency after both vaccines. There was a considerable increase in local reactions after the 3rd dose with both vaccines. Over 1000 doses of plain DTP (with no aluminium hydroxide adjuvant) were given during the study. Post-vaccination symptoms were more common after the plain than after the 2 adsorbed preparations.

Intersecting Pools and Their Potential Application in Testing Donated Blood for Viral Genomes

Amplification assays for viral genomes are at present too expensive and cumbersome to be applied to individual blood donations. Through constructing interesting pools of specimens, however, it may be possible to screen as a single process large numbers of units for several low prevalence viruses using relatively few tests. The preparation of the intersecting pools that would be required is explained in this paper. If test sensitivity and specificity were adequate, the testing of these pools would permit timely release of components that had the security of genetic testing added to current serological screening programmes. The method also makes screening for other viruses feasible.

Surveillance for the Impact in the UK of HIV Epidemics in South Asia

OBJECTIVES To determine whether, because of the extensive recent spread of HIV infection in South Asia, South Asians (those people who classify themselves as Indian, Pakistani, Bangladeshi or Sri Lankan in origin) resident in the UK were at increased risk of HIV infection and to review current surveillance systems for detecting any such increase. DESIGN Analysis of: ethnic grouping and probable country of infection recorded on voluntary confidential reports of AIDS cases and newly diagnosed HIV infections; blood donation testing data; reports of imported gonorrhoea infections; country of birth data from the unlinked anonymous (UA) survey of Sexually Transmitted Disease (STD) clinic attenders; district of residence data from the UA survey of pregnant women; ethnic grouping of prevalent diagnosed HIV infections. RESULTS Few reported AIDS cases or HIV infections were found in people of South Asian ethnic origin and few reported HIV or gonorrhoea infections were associated with exposure in South Asia. Data derived from the UA programme suggested as yet no increase in HIV prevalence in either STD clinic attenders born in South Asia or in pregnant women resident in districts containing substantial numbers of ethnic South Asians. CONCLUSIONS There was no evidence that South Asians resident in the UK are currently at greater risk of HIV infection than people of white ethnicity or, therefore, that south Asian heterosexuals are a group deserving priority in HIV prevention. However, as rapid spread of HIV infection is being recorded in the Indian subcontinent, continuous monitoring is necessary. This will be facilitated by improved collection of ethnic group information in all surveillance activities.

Three statistical tests for detecting overcounting of individuals in serological test data

In this paper we consider the amount of undetected replication in HIV infection diagnoses as reported to the Public Health Laboratory Service AIDS Centre, Colindale, London. These diagnoses are usually reported with the date of birth of the individual but no names held on the database. The PHLS cannot always tell whether two reports with the same date of birth correspond to the same individual. The number of replications of date of birth recorded in sixteen birth years was provided for investigation. This paper examines statistical methods for deciding whether there is a greater amount of replication of birthdates in the sample than expected by chance alone. Three methods are outlined. The first uses χ2-tests to compare the observed and expected number of i-tuples. The second uses a partial ranking scheme for the possible values of the replication vector and the third uses a test based on the number of pairs in a sample. Using a 5 % significance level, these tests reveal that, respectively, five out of the last eleven, one out of the first five and five out of the total sixteen birth years show evidence of more replication than expected by chance alone.

The epidemiology of HIV and AIDS in childhood

The epidemic of human immunodeficiency virus (HIV) and acquired immunodeficiency syndrome (AIDS) has been characterised as the greatest new threat to the public health this century. Initial descriptions focused upon its epidemiology amongst adults; more recently it has been appreciated that the spread of adult infection and maternal transmission have produced significant numbers of HIV infected children’ and, using a simple mathematical model, the World Health Organization (WHO) has estimated that by the end of 1992 over a million children will have been infected, with the heaviest burden falling in sub-Saharan Africa (Fig. l).’ This article describes the epidemiology of childhood infection with HIV-l. It will not consider HIV2 infection in children, as there is little relevant data. Modes of transmission are likely to be similar for the two viruses but adult data suggests that even in West Africa, where HIV-2 is prevalent, it is spreading less rapidly than HIV-l and hence it is likely to be of relatively minor significance elsewhere.3 Epidemiology of infection and modes of transmission