Results from a prospective sero-epidemiological study initiated in Uganda in 1971 indicate that children with high antibody titres to Epstein-Barr virus structural antigens are at high risk of developing Burkitt's lymphoma. These findings strongly support a causal relationship between the Epstein-Barr virus and Burkitt's lymphoma but suggest that the oncogenic potential of the virus is realised only in exceptional circumstances.

No abstract

From 1977 to 1982, the authors attempted a malaria suppression trial in North Mara District, Tanzania, to see whether the incidence of Burkitt's lymphoma (BL) could be lowered by reducing the level of malarial infection in a child population below 10 years of age. Immediately after initiation of the suppression trial, the prevalence of malaria fell drastically in the Mara children; however, soon after, the rate of malarial infection rose again in the trial area in spite of continued chloroquine distribution, and by 1981 the prevalence of malarial infection again reached the high levels that had prevailed in the North Mara lowlands before 1977. However, during the period of chloroquine distribution in North Mara, the level of malarial infection there was constantly lower than that observed in a comparison area in South Mara, although the two areas had been similar with respect to malaria endemicity prior to the intervention. During the years of chloroquine distribution in North Mara, the incidence rate of BL there fell considerably, from about 4 per 100,000 population to about 1 per 100,000 population, and it rose again to pretrial levels in 1984, that is, about two years after the chloroquine distribution had been terminated. This apparent association between malaria suppression and decline in BL incidence at first seemed to indicate that malaria is a causal factor in BL production. A close scrutiny of the survey data revealed, however, that the decline in BL incidence might have started several years before the chloroquine distribution began; thus it appears that the malaria suppression could not have been the sole cause of the BL decline.

A prospective epidemiological study was carried out in the West Nile District of Uganda from 1972 to 1979 in order to investigate the aetiological role of the Epstein-Barr virus (EBV) in Burkitt's lymphoma (BL). By 1976, fourteen BL cases had been detected among the 42,000 children originally bled in the study area. Testing of sera from BL candidates and neighbourhood controls showed that children who develop BL later have EBV/VCA titres several dilutions higher than their age- and sex-matched neighbours. This appearance of a strong EBV activity long before BL development was taken as evidence of a causal role of EBV in BL. In order to add to the unique material of pre-bled BL cases, BL detection was continued up to March 1979 when field work became impossible in Uganda. Two additional pre-bled BL cases were found during this extension of the study. The serological and virological evaluation of these additional cases showed that the EBV/VCA titres, but not the EA and EBNA titres, were about two dilutions higher in the BL candidates than in the controls. Hybridization assays showed that both lymphomas contained EBV/DNA in the tumour cells. These additional results thus confirm the findings in the first 14 cases and strengthen the epidemiological evidence for a causal role of the EBV in endemic BL.

Thirty-four males and 45 females who participated in household surveys 15 or 25 years earlier in rural Denmark were interviewed in 1982 about present and past food habits. Comparison of the information from the survey and the two interviews indicates that recall of past diet is strongly influenced by present dietary habits. As the relative classification of individuals according to their food habits appears to have changed little over time, information on current diet, perhaps supplemented by information on particular changes, can provide useful classification of individuals for epidemiologic purposes.

Epidemiological data relating to all 202 patients diagnosed with Burkitt's Lymphoma (BL) in the West Nile District of Uganda in the period 1961 to 1975 have been reviewed and analysed. Statistically significant evidence of space-time clustering of cases, first reported for the period 1961-65, was also present during 1972-73, but not during other periods. The patients involved in such clusters were found to be older than other patients (P less than 0.001). The average annual incidence of BL in the District was 2.45 x 10(-5) and overall there was no change in the incidence during the study period. However, there were statistically significant changes in incidence in different counties, which could not be explained as case-ascertainment artifacts. One sib pair of patients with BL was found and the series also included 7 instances of BL in two cousins. It is suggested that study of variation in the intensity and type of malarial infestation in different areas at different times may help explain the epidemiological findings and suggest what, if any, aspects of this infection are critical for inducing BL.

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Out of 72 Kaposi's sarcoma patients diagnosed between 1951 and March 1976 at Kuluva Hospital, West Nile District, Uganda, 64 with known co-ordinates were plotted on a map. Sixty-two of these were noted to live at an altitude of 853 metres or more (greater than or equal to 2,800 feet). Twenty-four patients were thought to be still alive and visits were made to their homes. Space-time grouping of four cases was noted on two occasions, although analysis did not reveal statistically significant clustering. A case-control study employing an interview questionnaire with 32 variables was performed on 19 patients and their age- and sex-matched neighbourhood controls, and sera were collected from both groups and from their families for estimation of viral antibody titres. The results demonstrated that cases tended to be post-pubertal males, a high proportion of whom had been bitten by a blood-sucking insect identified as being similar to Haematopota. Both cases and controls had raised antibody levels to cytomegalovirus, but cases obtained their drinking water more commonly from rivers whereas controls tended to use water from springs, boreholes or pipes.