Bill Hesselmar

Does early exposure to cat or dog protect against later allergy development

It is unknown which factors in modern western society that have caused the current increase in prevalence of allergic diseases. Improved hygiene, smaller families, altered exposure to allergens have been suggested.

Increase of asthma, allergic rhinitis and eczema in Swedish schoolchildren between 1979 and 1991

Background: A previous study has shown a twofold increase in prevalence of asthma and allergic rhinitis (AR) in Swedish recruits during the 1970s. The increase was higher in more northerly colder regions.

Reduced enterobacterial and increased staphylococcal colonization of the infantile bowel: an effect of hygienic lifestyle?

The modern Western lifestyle may have altered the composition of the commensal microflora. Here, we investigated the first years intestinal colonization pattern in 99 vaginally delivered Swedish infants and 17 delivered by cesarean section. Rectal swabs obtained at 3 d of age were cultured for aerobic bacteria and fecal samples obtained at 1, 2, 4, and 8 wk and at 6 and 12 mo of age were cultivated quantitatively for aerobic and anaerobic bacteria. Vaginally delivered infants more often had Escherichia coli compared with cesarean section–delivered infants, whereas the latter more frequently carried other enterobacteria, such as Klebsiella and Enterobacter. Independent of delivery mode, it took 2 mo until most infants were colonized by enterobacteria, traditionally the first colonizers. In contrast, coagulase-negative staphylococci colonized 99% of the infants from d 3 onwards. The poor adaptation of staphylococci to the gut was shown by declining population sizes after some weeks. Dominating anaerobes were initially bifidobacteria and clostridia, whereas Bacteroides initially colonized only 30% of vaginally delivered infants and increased very slowly in prevalence. Bacteroides colonization was delayed up to 1 y in cesarean section–delivered compared with vaginally delivered infants. Our results show that some “traditional” fecal bacteria are acquired late today especially in cesarean section–delivered infants, probably due to limited environmental circulation. In their absence, skin bacteria like staphylococci have become the first gut colonizers.

Escherichia coli in Infants' Intestinal Microflora: Colonization Rate, Strain Turnover, and Virulence Gene Carriage

Colonization by Escherichia. coli in infants might have decreased in the last decades, owing to changes in hospital routines and family lifestyle. In this study, the E. coli flora was characterized in 70 healthy Swedish infants followed for the first year of life. E. coli was isolated from rectal swabs obtained at 3 d of age and quantified in fecal samples collected at 1, 2, 4, and 8 wk of age and at 6 and 12 mo of age. Strains were typed using random amplified polymorphic DNA, and their virulence factor genes were identified by multiplex PCR. Colonization by E. coli occurred late; only 61% of the infants were positive by 2 mo of age. The turnover of individual strains in the microflora was slow (1.5 strains per infant during 6 mo, 2.1 during 1 y). Environmental factors, such as siblings, pets, or feeding mode, did not influence colonization kinetics or strain turnover rate. Genes encoding type 1 fimbriae, P fimbriae, and hemolysin were significantly more common in E. coli strains persisting for at least 3 wk in the microflora than in transient strains. The P-fimbrial class III adhesin gene was more common in E. coli from children who had a cat in their homes than in E. coli from children without pets (p = 0.01); this adhesin type is common in E. coli from cats. The late colonization and low E. coli strain turnover rate suggest limited exposure of Swedish infants to E. coli. Our results confirm that P fimbriae and other virulence factors facilitate persistence of E. coli in the human colonic microflora.

Prevalence of allergic diseases in schoolchildren in relation to family history, upper respiratory infections, and residential characteristics

The prevalences of asthma, allergic rhinitis (AR), and eczema were analyzed in relation to retrospective risk factors from birth in a questionnaire study of schoolchildren in two areas covering the whole climatic span of Sweden: the Göteborg area on the southwestern coast (7‐year‐olds, n= 1649) and Kiruna, a mining town in the northernmost inland mountains (7–9‐year‐olds, n= 832). The strongest background factor, a family history of the diseases, was more common in children with another strong risk factor, particularly for asthma: high frequency of upper respiratory tract infection (URTI). Other significant risk factors related to high indoor humidity caused an increased prevalence of both allergic diseases and URTI. Active mechanical ventilation of the homes caused a slight reduction of the prevalence of allergic diseases, and repainting or new wallpaper in the bedroom of the child after birth caused a moderately increased risk of allergic disease. This study illustrates the interaction between genetic and environmental risk factors with special emphasis on factors related to an unventilated indoor climate, which may have substantially contributed to the current increase of the diseases in the country.

Increased levels of circulating soluble CD14 but not CD83 in infants are associated with early intestinal colonization with Staphylococcus aureus

Background Soluble forms of the monocyte marker CD14 and the mature dendritic cell marker CD83 are plasma proteins with immunoregulatory functions. The physiological stimulus for their production is unclear and their possible role in allergy development is unknown.

Allergic rhinoconjunctivitis, eczema, and sensitization in two areas with differing climates

In this 5‐year follow‐up study we compared the prevalence of allergic rhinoconjunctivitis, eczema, and sensitization, in relation to several background factors, in two Swedish regions (Göteborg and Kiruna). In Göteborg, a city on the southwest coast, the climate is mild and humid. Kiruna is a town north of the Arctic Circle. Questionnaire replies and results of interviews were collected from all 412 7–8‐year‐old children of a population‐based sample (203 in Göteborg and 209 in Kiruna); in addition, 192 children from Göteborg and 205 from Kiruna were skin‐prick tested for sensitization to common aero‐allergens. After 5 years, at 12–13 years of age, almost all of the initial study cohort were re‐investigated. At follow‐up the prevalence of allergic rhinoconjunctivitis was 17%, eczema 23%, and sensitization 32%. Allergic rhinoconjunctivitis and eczema were as common in Göteborg as in Kiruna, whereas sensitization was far more common in Kiruna. Children born during the pollen season had allergic rhinoconjunctivitis less often – and were sensitized to pollen and animal protein less often – than those born during the rest of the year. Sensitization to birch pollen, cat protein, and horse protein was less common in children living in Göteborg, the region with the highest frequency of cat ownership and horseback riding, and with the longest birch‐pollen season. The girls were more commonly horseback riders but the boys were more often sensitized to horses. The results reinforce our previous findings: indoor climate may affect the development of sensitization and allergic diseases, to some extent independently; and if exposure to antigen is unavoidable, high doses might be better than low doses.

Early fish introduction is associated with less eczema, but not sensitization, in infants

Objective:  To investigate if the development of allergic diseases during the child’s first 18 months of life is influenced by the time at which different food items were introduced into the child’s diet.

High-dose exposure to cat is associated with clinical tolerance – a modified Th2 immune response?

Background Allergen‐specific IgG4 antibodies, it is suggested, may be protecting against allergy development by blocking responses. Levels are proposed as a marker of modified Th2 response.

Pacifier Cleaning Practices and Risk of Allergy Development

OBJECTIVE: Immune stimulation through exposure to commensal microbes may protect against allergy development. Oral microbes may be transferred from parents to infants via pacifiers. We investigated whether pacifier cleaning practices affected the risk of allergy development. METHODS: A birth-cohort of 184 infants was examined for clinical allergy and sensitization to airborne and food allergens at 18 and 36 months of age and, in addition, promptly on occurrence of symptoms. Pacifier use and pacifier cleaning practices were recorded during interviews with the parents when the children were 6 months old. The oral microbiota of the infants was characterized by analysis of saliva samples collected at 4 months of age. RESULTS: Children whose parents “cleaned” their pacifier by sucking it (n = 65) were less likely to have asthma (odds ratio [OR] 0.12; 95% confidence interval [CI] 0.01–0.99), eczema (OR 0.37; 95% CI 0.15–0.91), and sensitization (OR 0.37; 95% CI 0.10–1.27) at 18 months of age than children whose parents did not use this cleaning technique (n = 58). Protection against eczema remained at age 36 months (hazard ratio 0.51; P = .04). Vaginal delivery and parental pacifier sucking yielded independent and additive protective effects against eczema development. The salivary microbiota differed between children whose parents cleaned their pacifier by sucking it and children whose parents did not use this practice. CONCLUSIONS: Parental sucking of their infant’s pacifier may reduce the risk of allergy development, possibly via immune stimulation by microbes transferred to the infant via the parent’s saliva.