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New predictions for total vCJD mortality lower than before
SCIENCE AND MEDICINE
New predictions for total vCJD mortality lower than before maximum of 136 000 cases of new variant Creutzfeldt-Jakob disease (vCJD) could occur in Great Britain in the aftermath of the bovine spongiform encephalopathy (BSE) epidemic, according to calculations by Neil Ferguson and colleagues at the University of Oxford, UK. This figure is much lower than their previous prediction of a maximum of 500 000 cases. The total number of cases will depend on various factors, including the incubation period, which is as yet unknown. But the final count cannot reach more than 6000 unless the incubation period is about as long as the average human
A
life expectancy, the authors say. About 750 000 cattle infected with BSE were slaughtered for human consumption between 1980 and 1996, but so far there have been only 79 confirmed or probable cases of vCJD. Ferguson’s projections for the eventual total number of cases of vCJD range from a low of between 63 (already exceeded) and 350 (if there are fewer than ten new cases on average for each of years 2000–2002, and an incubation period of less than 20 years) to a high of between 1300 and 136 000 (if the yearly average rises above 20 cases, and the incubation period is 60 years or more). The
BSE epidemic in sheep unlikely, report says Fears of an epidemic of BSE in British sheep flocks (Lancet 2000; 356: 315) are probably unfounded, according to a report from the Institute for Animal Health, Compton, UK (Nature 2000; 406: 584–85). Successful experimental transmission of BSE to sheep raised the possibility that some sheep in the UK could have been infected during the 1980s after exposure to BSE-infected animal feed. “BSE could be misdiagnosed as scrapie, but there is no evidence of a peak in scrapie before, during, or after in association with the outbreak of BSE in cattle”, says lead investigator Mike Gravenor. Instead, “the incidence of sheep spongiform encephalopathy has been rising gradually since 1962”.
authors add that the upper and lower limits depend also on the relative infectivity of cattle at different incubation stages, and the effectiveness of control measures in reducing exposure of human beings to infected material, such as the introduction of the ban on beef offal in the early 1990s (Nature 2000; 406: 583–84). Current data, say Ferguson’s group, suggest that no more than two cases of vCJD, on average, could arise from the consumption of two maximally infected bovines, indicating “a substantial species barrier, given that thousands of people might eat meat from a single animal”. Hester Ward (National CJD Surveillance Unit, Edinburgh, UK) adds: “We have observed what appears to be a statistically significant increase in the incidence of vCJD in the UK, which is a cause for concern. However, the incidence is increasing from a very low base, and absolute numbers remain relatively small. These results are not compatible with the predictions of Ferguson’s group.”
Dorothy Bonn Dorothy Bonn
News in Brief Name that tune! The case of a 57-year-old man who experienced auditory hallucinations while recovering from an abscess with bacterial meningitis in the dorsal pons is described by a group of German neurologists this week. The man’s condition improved after treatment with antibiotics, but during recovery he complained of acoustic hallucinations in his right ear which consisted of boys’ choirs singing shanty, folk, and carnival songs (Neurology 2000; 55: 454–55). Switch off the fat A molecular switch that can control the formation of fat cells in mice could help scientists understand how and why obesity develops, according to a report by researchers from the University of Michigan, MI, USA. The switch, a protein called Wnt10b, represses the formation of fatcells; its absence causes muscle-cell precursors to be reprogrammed to undergo adipogenesis, so that they turn into fat cells (Science 2000; 289: 950–53).
570
Rickets returns to African-American babies
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ll dark-skinned breastfed babies should be given vitamin D supplementation to counteract the current resurgence of nutritional rickets in the USA, say Shelley Kreiter and colleagues in this month’s Journal of Pediatrics. (2000; 137: 153–57). “We support breastfeeding as the ideal nutrition for babies and children, but recommend supplementation of all dark-skinned, breastfed infants and children with 400 IU of vitamin D per day starting at least by 2 months of age”, say the investigators from Wake Forest University School of Medicine (WinstonSalem, NC) and the University of North Carolina School of Medicine (Chapel Hill, NC). The researchers retrospectively analysed the 30 cases of nutritional rickets seen at the two medical centres between 1990 and June last year. The children, aged between 5 and 25 months at diagnosis, were all African Americans who were breastfed and received no supplemental vitamin D. “Particularly concerning is that over half the cases were diagnosed in the past 18
months”, note the investigators. The most common presenting signs and symptoms were skeletal abnormalities and failure to thrive: “The vast majority of the patients were growth retarded in both height and weight by the time of diagnosis, and nearly one-third were severely growth retarded.” All children were hypophosphataemic and had raised alkaline phosphatase concentrations; 18 (60%) were hypocalcaemic and decreased vitamin D concentrations were found in 19 of the 23 patients in which it had been measured. The researchers postulate that the main reason for the re-emergence of rickets is the increase in the proportion of women who breastfeed their babies, especially younger African Americans; during 1988–98 the number of African Americans breastfeeding their babies increased more than fourfold. In addition, inadequate supplementation and decreased exposure to sunlight may contribute, say the authors. Sarah Ramsay
THE LANCET • Vol 356 • August 12, 2000
For personal use only. Not to be reproduced without permission of The Lancet.
New predictions for total vCJD mortality lower than before maximum of 136 000 cases of new variant Creutzfeldt-Jakob disease (vCJD) could occur in Great Britain in the aftermath of the bovine spongiform encephalopathy (BSE) epidemic, according to calculations by Neil Ferguson and colleagues at the University of Oxford, UK. This figure is much lower than their previous prediction of a maximum of 500 000 cases. The total number of cases will depend on various factors, including the incubation period, which is as yet unknown. But the final count cannot reach more than 6000 unless the incubation period is about as long as the average human
A
life expectancy, the authors say. About 750 000 cattle infected with BSE were slaughtered for human consumption between 1980 and 1996, but so far there have been only 79 confirmed or probable cases of vCJD. Ferguson’s projections for the eventual total number of cases of vCJD range from a low of between 63 (already exceeded) and 350 (if there are fewer than ten new cases on average for each of years 2000–2002, and an incubation period of less than 20 years) to a high of between 1300 and 136 000 (if the yearly average rises above 20 cases, and the incubation period is 60 years or more). The
BSE epidemic in sheep unlikely, report says Fears of an epidemic of BSE in British sheep flocks (Lancet 2000; 356: 315) are probably unfounded, according to a report from the Institute for Animal Health, Compton, UK (Nature 2000; 406: 584–85). Successful experimental transmission of BSE to sheep raised the possibility that some sheep in the UK could have been infected during the 1980s after exposure to BSE-infected animal feed. “BSE could be misdiagnosed as scrapie, but there is no evidence of a peak in scrapie before, during, or after in association with the outbreak of BSE in cattle”, says lead investigator Mike Gravenor. Instead, “the incidence of sheep spongiform encephalopathy has been rising gradually since 1962”.
authors add that the upper and lower limits depend also on the relative infectivity of cattle at different incubation stages, and the effectiveness of control measures in reducing exposure of human beings to infected material, such as the introduction of the ban on beef offal in the early 1990s (Nature 2000; 406: 583–84). Current data, say Ferguson’s group, suggest that no more than two cases of vCJD, on average, could arise from the consumption of two maximally infected bovines, indicating “a substantial species barrier, given that thousands of people might eat meat from a single animal”. Hester Ward (National CJD Surveillance Unit, Edinburgh, UK) adds: “We have observed what appears to be a statistically significant increase in the incidence of vCJD in the UK, which is a cause for concern. However, the incidence is increasing from a very low base, and absolute numbers remain relatively small. These results are not compatible with the predictions of Ferguson’s group.”
Dorothy Bonn Dorothy Bonn
News in Brief Name that tune! The case of a 57-year-old man who experienced auditory hallucinations while recovering from an abscess with bacterial meningitis in the dorsal pons is described by a group of German neurologists this week. The man’s condition improved after treatment with antibiotics, but during recovery he complained of acoustic hallucinations in his right ear which consisted of boys’ choirs singing shanty, folk, and carnival songs (Neurology 2000; 55: 454–55). Switch off the fat A molecular switch that can control the formation of fat cells in mice could help scientists understand how and why obesity develops, according to a report by researchers from the University of Michigan, MI, USA. The switch, a protein called Wnt10b, represses the formation of fatcells; its absence causes muscle-cell precursors to be reprogrammed to undergo adipogenesis, so that they turn into fat cells (Science 2000; 289: 950–53).
570
Rickets returns to African-American babies
A
ll dark-skinned breastfed babies should be given vitamin D supplementation to counteract the current resurgence of nutritional rickets in the USA, say Shelley Kreiter and colleagues in this month’s Journal of Pediatrics. (2000; 137: 153–57). “We support breastfeeding as the ideal nutrition for babies and children, but recommend supplementation of all dark-skinned, breastfed infants and children with 400 IU of vitamin D per day starting at least by 2 months of age”, say the investigators from Wake Forest University School of Medicine (WinstonSalem, NC) and the University of North Carolina School of Medicine (Chapel Hill, NC). The researchers retrospectively analysed the 30 cases of nutritional rickets seen at the two medical centres between 1990 and June last year. The children, aged between 5 and 25 months at diagnosis, were all African Americans who were breastfed and received no supplemental vitamin D. “Particularly concerning is that over half the cases were diagnosed in the past 18
months”, note the investigators. The most common presenting signs and symptoms were skeletal abnormalities and failure to thrive: “The vast majority of the patients were growth retarded in both height and weight by the time of diagnosis, and nearly one-third were severely growth retarded.” All children were hypophosphataemic and had raised alkaline phosphatase concentrations; 18 (60%) were hypocalcaemic and decreased vitamin D concentrations were found in 19 of the 23 patients in which it had been measured. The researchers postulate that the main reason for the re-emergence of rickets is the increase in the proportion of women who breastfeed their babies, especially younger African Americans; during 1988–98 the number of African Americans breastfeeding their babies increased more than fourfold. In addition, inadequate supplementation and decreased exposure to sunlight may contribute, say the authors. Sarah Ramsay
THE LANCET • Vol 356 • August 12, 2000
For personal use only. Not to be reproduced without permission of The Lancet.