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IgE not to blame for food allergy in adults
THE LANCET
SCIENCE AND MEDICINE
FDA urges approval of oral HIB vaccine
O
n July 11, a US Food and Drug Administration advisory committee unanimously urged for the approval of a new paediatric oral Haemophilus influenzae type b vaccine. PedVax HIB is a new formulation of a Merck vaccine that has been on the market since 1990 but which, at 7·5 g, is half the dose. This formulation will be simpler to manufacture and administer, said Merck, which noted that it will be sold in a preservativefree single-dose package. It will also have less carrier protein than the currently marketed product. Merck presented data to the committee from a pivotal trial comparing the current vaccine—a 15 g lyophilised dose—to the liquid 7·5 g dose. The 15 g vaccine was given to 228 healthy infants, and the oral dose to 680 healthy infants at ten sites around the USA. The infants’ median age was 2 months. Efficacy and safety results were similar for both products, and there were no vaccine-attribut able adverse events, according to Merck. FDA reviewers and committee members agreed with Merck that the 5-year safety record of the lyophilised vaccine indicates that the lower dose oral formulation is likely to be just as safe. Patricia Ferrieri, chairperson of the panel and professor of medicine at the University of Minnesota, said that the studies presented by Merck “are as clear as anyone could ever hope for”. The oral vaccine, if approved by FDA, will be given in the same dosing regimen as the current product: one shot at age 2–6 months, another 2 months later, and then a third at age 12–15 months.
Alicia Ault Barnett
US bad berries may be from below the border
T
he New Jersey Department of Health and Senior Services has linked two clusters—of diarrhoeal disease caused by Cyclospora cayetanensis—to raspberries. Officials cannot be completely certain of the berries’ origin, but it is likely that they are from Guatemala. In one cluster, 45 of 130 attendees at a party in Princeton, NJ, became ill with laboratory confirmed cyclospora. At the party, a dessert was served consisting of strawberries from California and black and red raspberries from Guatemala. The second cluster also seems to have been brought on by raspberry ingestion, this time at a restaurant in New York City. But the origin of those berries remains untraceable. Following these events, NJ state epidemiologists conducted a casecontrol study of 30 cases and 60 age
and sex matched controls. All cases have had confirmed cyclospora infection since May; all are regarded as sporadic cases and not members of the two clusters. Study participants were questioned on water, soil, and animal exposure and on ingestion of 17 fruits and 15 vegetables. Early inspection of the data shows that the single independent risk factor for cyclospora infection is raspberry consumption. The US Department of Agriculture California Berry Report (Fruit and Vegetable Market News, 1996) says that US importation of Guatemalan raspberries rose from 28 000 units in 1994 to 162 000 by June 21 this year. Other sources of US raspberries include Chile, Colombia, and Mexico. David H Frankel
How folic acid might prevent neural-tube defects
M
ice homozygous for a mutation in the Cart1 gene, which normally encodes cartilage homoeoprotein 1, are born with severe cranial defects and partial anencephaly, a phenotype similar to human anencephaly. Like affected human babies, the mutant mice die shortly after birth. But, as shown by Qi Zhao and colleagues of the Anderson Cancer Center, Houston, USA, most mutant offspring of heterozygous females treated with folic acid in the first half of gestation are born with a fully formed cranium (Nature Genet 1996; 13: 275–83).
(All the mice died within 2 days of birth, probably because the chosen folic acid regimen failed to prevent the associated brain abnormalities.) The authors speculate that folic acid alters head mesenchyme, allowing closure of the forebrainmidbrain boundary, the site of the developmental block in neural-tube defects (NTDs), to be initiated. They suggest that mutant Cart1, which causes abnormal apoptosis in the forebrain and subsequent absence of forebrain mesenchyme cells, is a homologue of one of possibly several human genes involved in the development of NTDs. M
IgE not to blame for food allergy in adults
N
o evidence for IgE-mediated allergy has emerged from a Swedish study of adults with a history of gastrointestinal symptoms related to eating staple foods such as cows’ milk and wheat flour (Gut 1996; 39: 130–35). U Bengtsson and colleagues in Göteborg, Sweden, used double-blind, placebo-controlled food challenge (DBPCFC) to verify sensitivity to specific foods, and patients who had a positive reaction were then given skin-prick tests
Vol 348 • July 20, 1996
(SPT) and radioallergosorbent tests (RAST) for the suspect foods. 96 patients with food-related abdominal symptoms kept a food diary for 14 days, and those whose symptoms appeared to be related to eating specific staple foods (eggs, milk, wheat flour, rye flour) were given an elimination diet, excluding the suspect foods, for 1–2 weeks. 36 patients whose symptoms returned when the food was reintroduced went on to take part in the DBPCFC, and
15 had a positive reaction. SPT and RAST results for the relevant allergens were negative in all 15. IgEmediated allergy, often implicated in food allergy in children, thus seems to be rare in adults. In the study, atopic allergy to inhaled allergens was no more common in the doubleblind positive group than in negative controls—20% and 19%, respectively, had a strongly positive SPT. Dorothy Bonn
185
SCIENCE AND MEDICINE
FDA urges approval of oral HIB vaccine
O
n July 11, a US Food and Drug Administration advisory committee unanimously urged for the approval of a new paediatric oral Haemophilus influenzae type b vaccine. PedVax HIB is a new formulation of a Merck vaccine that has been on the market since 1990 but which, at 7·5 g, is half the dose. This formulation will be simpler to manufacture and administer, said Merck, which noted that it will be sold in a preservativefree single-dose package. It will also have less carrier protein than the currently marketed product. Merck presented data to the committee from a pivotal trial comparing the current vaccine—a 15 g lyophilised dose—to the liquid 7·5 g dose. The 15 g vaccine was given to 228 healthy infants, and the oral dose to 680 healthy infants at ten sites around the USA. The infants’ median age was 2 months. Efficacy and safety results were similar for both products, and there were no vaccine-attribut able adverse events, according to Merck. FDA reviewers and committee members agreed with Merck that the 5-year safety record of the lyophilised vaccine indicates that the lower dose oral formulation is likely to be just as safe. Patricia Ferrieri, chairperson of the panel and professor of medicine at the University of Minnesota, said that the studies presented by Merck “are as clear as anyone could ever hope for”. The oral vaccine, if approved by FDA, will be given in the same dosing regimen as the current product: one shot at age 2–6 months, another 2 months later, and then a third at age 12–15 months.
Alicia Ault Barnett
US bad berries may be from below the border
T
he New Jersey Department of Health and Senior Services has linked two clusters—of diarrhoeal disease caused by Cyclospora cayetanensis—to raspberries. Officials cannot be completely certain of the berries’ origin, but it is likely that they are from Guatemala. In one cluster, 45 of 130 attendees at a party in Princeton, NJ, became ill with laboratory confirmed cyclospora. At the party, a dessert was served consisting of strawberries from California and black and red raspberries from Guatemala. The second cluster also seems to have been brought on by raspberry ingestion, this time at a restaurant in New York City. But the origin of those berries remains untraceable. Following these events, NJ state epidemiologists conducted a casecontrol study of 30 cases and 60 age
and sex matched controls. All cases have had confirmed cyclospora infection since May; all are regarded as sporadic cases and not members of the two clusters. Study participants were questioned on water, soil, and animal exposure and on ingestion of 17 fruits and 15 vegetables. Early inspection of the data shows that the single independent risk factor for cyclospora infection is raspberry consumption. The US Department of Agriculture California Berry Report (Fruit and Vegetable Market News, 1996) says that US importation of Guatemalan raspberries rose from 28 000 units in 1994 to 162 000 by June 21 this year. Other sources of US raspberries include Chile, Colombia, and Mexico. David H Frankel
How folic acid might prevent neural-tube defects
M
ice homozygous for a mutation in the Cart1 gene, which normally encodes cartilage homoeoprotein 1, are born with severe cranial defects and partial anencephaly, a phenotype similar to human anencephaly. Like affected human babies, the mutant mice die shortly after birth. But, as shown by Qi Zhao and colleagues of the Anderson Cancer Center, Houston, USA, most mutant offspring of heterozygous females treated with folic acid in the first half of gestation are born with a fully formed cranium (Nature Genet 1996; 13: 275–83).
(All the mice died within 2 days of birth, probably because the chosen folic acid regimen failed to prevent the associated brain abnormalities.) The authors speculate that folic acid alters head mesenchyme, allowing closure of the forebrainmidbrain boundary, the site of the developmental block in neural-tube defects (NTDs), to be initiated. They suggest that mutant Cart1, which causes abnormal apoptosis in the forebrain and subsequent absence of forebrain mesenchyme cells, is a homologue of one of possibly several human genes involved in the development of NTDs. M
IgE not to blame for food allergy in adults
N
o evidence for IgE-mediated allergy has emerged from a Swedish study of adults with a history of gastrointestinal symptoms related to eating staple foods such as cows’ milk and wheat flour (Gut 1996; 39: 130–35). U Bengtsson and colleagues in Göteborg, Sweden, used double-blind, placebo-controlled food challenge (DBPCFC) to verify sensitivity to specific foods, and patients who had a positive reaction were then given skin-prick tests
Vol 348 • July 20, 1996
(SPT) and radioallergosorbent tests (RAST) for the suspect foods. 96 patients with food-related abdominal symptoms kept a food diary for 14 days, and those whose symptoms appeared to be related to eating specific staple foods (eggs, milk, wheat flour, rye flour) were given an elimination diet, excluding the suspect foods, for 1–2 weeks. 36 patients whose symptoms returned when the food was reintroduced went on to take part in the DBPCFC, and
15 had a positive reaction. SPT and RAST results for the relevant allergens were negative in all 15. IgEmediated allergy, often implicated in food allergy in children, thus seems to be rare in adults. In the study, atopic allergy to inhaled allergens was no more common in the doubleblind positive group than in negative controls—20% and 19%, respectively, had a strongly positive SPT. Dorothy Bonn
185