加州大學研究提醒貓奴 對貓敏感患青光眼風險多90%

【本報訊】美國加州大學最近一項研究引起一眾「貓奴」關注，該研究指貓隻身上的致敏物質，可引發人體免疫反應，集中影響視覺神經，增加患上青光眼風險，嚴重可致盲。本港免疫學專家估計，貓隻致敏原體積較細又較輕，可懸浮在空氣中，眼睛易受刺激引致雙眼反覆發炎，導致罹患青光眼；但眼科專家強調，現時仍未有足夠數據支持上述論點，臨床上也沒有相關個案，籲大眾毋須憂慮。

■8貓之主Michael不擔心養貓會影響視力。

馬泉崇

攝

人體接觸到致敏物質時，會出現眼痕和打噴嚏等過敏反應。美國加州大學的研究人員找來1,678名年齡介乎50至60歲人士，測試面對不同來源過敏反應。結果發現，會對來自貓隻致敏物質出現過敏反應的參加者，罹患青光眼的風險較其他參加者，增加九成。

研究人員認為，貓隻身上的致敏物質擁有某種生物化學特性，可令部份人體內的抗體水平急升，引起過敏反應之餘，抗體更會集中對視覺神經造成影響，繼而增加罹患青光眼的風險。

本港現時於公立醫院求診的青光眼病人有4萬多人。眼科專科醫生袁國禮指出，青光眼於本港屬於常見的眼疾之一，成因包括本身眼部結構有問題、眼部曾受傷、曾使用含類固醇的眼藥水，以及隨年紀增長眼部肌肉退化等，都可影響眼內壓力，損害眼部神經，導致青光眼，但袁國禮在臨床上卻未曾見過與對貓隻敏感相關的個案，認為難以憑上述的研究，定下接觸貓隻就會增加罹患青光眼風險的論點，「仲需要更多數據支持」。

■本港現時有4萬多名青光眼病人於公立醫院求診，為本港常見眼疾之一。

醫生：或受致敏物質刺激發炎

免疫及過敏病科專科醫生鄔揚源則估計，對貓過敏者因眼睛經常受致敏物質刺激而反覆發炎，或因此增加他們罹患青光眼的風險。他建議，家中放置空氣清新機，或在醫生建議下使用藥物進行脫敏治療，可減少對貓隻的過敏反應。

至於對狗隻過敏又會否影響雙眼健康？鄔醫生指出，貓隻身上的致敏物質，體積較細並較輕，易於空氣中懸浮，接觸到主人雙眼，有可能令眼睛產生過敏反應。不過，狗隻身上的致敏物質較大及重，較少機會接觸主人雙眼。

有份照顧「尖東忌廉哥」的店員英姐指「都好少哄得太埋，而且經常會幫佢梳毛，唔畀啲毛周圍飛，亦唔會太擔心敏感問題」。而家中飼養了8隻貓的Michael經常利用除塵棒清潔貓毛，他指「為咗照顧啲貓，我𠵱家仲少咗用電腦或睇電視，對眼健康咗」，不會因為研究而覺得擔心。

參考資料:  蘋果曰報
以上所提供的資訊僅作為教育及參考用途，如果你有任何醫療問題，
應向自己的過敏病科醫生查詢，而不應單倚賴以上提供的資料。

新研究印證 小胖子易哮喘 (下)

藥控病情
　　
一旦哮喘發作，出現咳嗽不止、氣促、胸口不適及呼吸時發出喘鳴聲時，患者需要根據醫生指示使用藥物控制病情。病情輕微患者可選用氣管舒張劑，但若病情嚴重，有可能需要使用消炎藥物，例如口服特效消炎藥，或吸入性類固醇，治療氣管慢性發炎及預防哮喘發作。

預防五法

1.遠離二手煙：吸煙是誘發哮喘的重要源頭，母親於懷孕期間絕不應吸煙，兒童成長過程亦應遠離二手煙。

2.避免接觸致敏原：大部分哮喘患者均對塵ë敏感而致病，故必須保持家居清潔。居室應避免鋪地毯，脇單被鋪要經常更換，最好用攝氏六十度熱水清洗，並在陽光下晾曬。可使用防塵ë脇上用品，研究發現羽毛枕較乳膠枕少藏塵ë，另應避免給兒童玩毛公仔。

3.適量運動：強健體魄有助增強抵抗力，預防病毒入侵，減低誘發哮喘的風險。哮喘病情受控時，運動量毋須受限制。

4.多曬太陽：維他命D攝取不足會增患過敏疾病的機會，給小孩適量曬太陽，有助攝取維他命D。

5.脫敏治療：患有鼻敏感的兒童可考慮透過脫敏治療，減低日後患哮喘的機率。脫敏所用的過敏原疫苗根據病人的敏感測試結果而配製，定期注射過敏原疫苗會產生免疫忍耐反應。當患者對過敏原敏感反應逐漸減少時，症狀便得以舒緩。一般經過三至五年治療後，效果可長期持續。




參考資料:  http://hd.stheadline.com/
以上所提供的資訊僅作為教育及參考用途，如果你有任何醫療問題，
應向自己的過敏病科醫生查詢，而不應單倚賴以上提供的資料。

新研究印證 小胖子易哮喘 (上)

香港不少兒童受哮喘病困擾，須時刻提防病發。最近再有研究印證，哮喘除了受家族遺傳影響，肥胖亦是誘因之一。這項美國科研發現，超重孩童患哮喘風險比正常體重孩子高一成多。過敏科醫生提醒家長，除須注意小孩體重，如有家族病史，應遠離致敏原，以減誘發機率。

胖童心肺負荷較大

美國一項研究發現，超重兒童患哮喘的風險，較正常體重孩童高出16%，癡肥孩子更高出37%。過敏科醫生鄔揚源表示，過去亦曾有多項研究證實，肥胖兒童患哮喘機會的確較高，「原因可能是胖童本身運動量少，加上由於身體較重，心肺功能負荷較大，因而增加誘發哮喘的風險。」鄔醫解生釋。

塵蟎敏感致病

鄔醫生強調，肥胖不但增加哮喘風險，日後患上其他疾病如心血管疾病風險亦較高，故家長必須避免小童過胖。另一方面，哮喘主要受家族遺傳影響。香港十四歲學童約有12%患上此症，鄔醫生指出，大部分哮喘患者均是對塵ë敏感所致，要預防哮喘，最佳方法除了保持適當體重外，還應遠離致敏原。

高危因素

‧家族病史：若父母雙方均有過敏性疾病，下一代患過敏性疾病的機率，例如哮喘、濕疹及鼻敏感等，較平常人高60%至80%。若只是母親患有，小朋友罹患機會較平常人高30%至40%。


‧肥胖：超重兒童患哮喘的風險，比起正常體重者高出16%，癡肥孩子的機率更高出37%。


‧濕疹病童：由於病童的皮膚屏障基因先天出錯，以致皮膚屏障功能出現障礙，外來刺激物經皮膚接觸而刺激免疫系統，引致出現過敏反應，誘發哮喘。小時候患有濕疹的孩童，日後患哮喘機會較其他人高兩至三倍。


‧鼻敏感：鼻敏感是哮喘的先兆，兒童一旦有鼻敏感徵狀，家長便應提高警覺，採取更多遠離致敏原的措施。

.......續




參考資料:  http://hd.stheadline.com/
以上所提供的資訊僅作為教育及參考用途，如果你有任何醫療問題，
應向自己的過敏病科醫生查詢，而不應單倚賴以上提供的資料。

Immunotherapy for allergic diseases (2)

 

 

So how do we treat allergies?  The most obvious answer is to avoid coming in contact with allergens.  To successfully practice allergen avoidance, we must first find out what the person is allergic to, and to confirm that these allergens are responsible for their symptoms.  A positive skin test will identify allergens that the patient responds to immunologically, but it still does not confirm that these allergens cause symptoms from day to day.   

 

A careful history will be very helpful, but sometimes, challenge studies might be needed.  Measuring the level of allergens in the patient’s living and working environment might also be useful.  For certain indoor allergens such as house dust mites and animal dander, avoidance measures can be extremely helpful.  The second line of treatment for allergies is drug treatment.   

 

Drugs such as antihistamines are used to counteract some of the symptoms of an allergic reaction.  They can be useful for mild cases but are frequently not successful in controlling more severe cases.  Steroid spray is also very useful in reducing the inflammation caused by an allergic reaction.  These treatments do not address the root of the problem, and symptoms promptly recur once the patient stops the treatments.

 

The only method to eliminate allergies is by immunotherapy.  This form of therapy aims to induce immunological tolerance to specific allergens, so that patients will no longer react to them when exposed.  Traditionally, immunotherapy (also called allergy injections or desensitization) is administered by repeated subcutaneous injections of purified allergen extracts.  

 

 This carries a risk of severe allergic reactions, and the injections must be administer under the supervision of an experienced allergist with adequate emergency support.  In experienced hands, immunotherapy is very safe, especially if standardized extracts are used.  In patients with insect sting allergy, immunotherapy is >99% effective in protecting the patients from future stings, and the effect appears to be lifelong after 3 to 5 years of continuous treatment.  The effectiveness of pollen immunotherapy has also been shown to last for at least 3 years after stopping treatment.

 

Newer forms of immunotherapy are being developed.  Sublingual immunotherapy uses a very high dose of allergen extract to be placed under the tongue for absorption.  Initial studies suggest that it might be effective for allergic rhinitis and possibly asthma.  More studies are needed to confirm its efficacy and also to determine its mechanism of action.  We are currently conducting a large clinical study, which will eventually involve 120 patients with allergic rhinitis, to evaluate sublingual immunotherapy against house dust mites.  

 

 Patients with moderate to severe allergic rhinitis will be recruited.  Skin tests to common allergens will be performed to confirm sensitization to house dust mites.  A nasal challenge study will be performed to confirm that house dust mites can indeed cause nasal symptoms.  The patients will first be given conventional drug therapy including an antihistamine and a nasal spray.   

 

Patients who do not derive satisfactory results from this treatment will be randomized to receive immunotherapy or placebo for one year.  The patients will be reevaluated every three months, and those that respond to treatment will have their nasal spray gradually withdrawn.  Patients will fill in a report of their symptoms every week.  At the end of one year, all patients on active treatment will continue for another year, and those on placebo will be switched to active treatment.  Immunological parameters in the blood and nasal washings will be evaluated at the beginning of the study and after one year.]

 

 

Reference information:  www.allergy.hk

The information aims to provide educational purpose only. Anyone reading it should consult physician before considering treatment and should not rely on the information above.

Immunotherapy for allergic diseases (1)

 

 

 

Allergic diseases are some of the most common diseases in Hong Kong.  It has been estimated that up to 50% of school children suffer from symptoms of rhinitis, while about 15% of them have asthma and about 10% have eczema.  The incidence of allergic diseases is also increasing around the world, as a result of changes in our lifestyle and our environment.

 

Allergic rhinitis/conjunctivitis is a common problem that many sufferers simply ignore.  The symptoms include sneezing, itchy nose, itchy eyes, runny nose, watery eyes, congestion and post-nasal drip.  However, severe cases can be quite debilitating.  Children with allergic rhinitis have been shown to suffer from poor sleep, impaired learning, bad temper and hyperactivity.  Adults with allergic rhinitis are at risk of disorders of mood and sleep.  Severe allergic rhinitis might become complicated by sinus and middle ear infections, worsening of asthma, and might affect facial and dental development in children.

 

The cause of allergic rhinitis in any individual is dependent on his/her living and working environment.  In temperate climate, pollens are the most common causes.  However, in subtropical climates such as Hong Kong, indoor allergens such as house dust mites, mould spores, cockroaches and animal dander are the most common causes.  Exposure to allergens in the work environment is also very important.

 

Why do people develop allergies?  When we are first exposed to a foreign substance, through our skin, our respiratory tract or GI tract, our immune system will strive to recognize this substance.  In most cases, our immune system recognizes that these substances are harmless and ignores them.  This is a process called immunological tolerance.  Not only does the immune system ignore these antigens, it actually develops a response that actively suppresses any reaction to the antigens.  This active suppression can be passed on from one experimental animal to another by transferring immune cells called T cells.  In allergic individuals, this mechanism somehow failed to work for certain antigens (allergens), and they develop an immune response every time they encounter these antigens.  This immune response leads to allergic symptoms.

 

 

Reference information: www.allergy.hk

The information aims to provide educational purpose only. Anyone reading it should consult
physician before considering treatment and should not rely on the information above.

防治哮喘刻不容緩

當季節轉換時，環境溫度和濕度的轉變會令哮喘患者的呼吸道有不適的感覺，有些患者會在這個季節病情出現反覆，因此，每當春季來臨亦是哮喘發作的高峰期。

哮喘屬於支氣管收窄的疾病。患者因吸入了環境致敏原，如塵蟎、霉菌、動物毛髮、花粉或污濁空氣等而導致過敏性發炎，患者的氣管因發炎而引致氣管收窄，若發炎的情況嚴重更會令氣管的肌肉收縮而導致呼吸困難。有部份哮喘患者同時亦是鼻敏感或濕疹病人。

除此之外，亦有病人因阿士匹靈過敏症而誘發哮喘，此類病人多屬遺傳關係，而發病亦多在成年時候。

哮喘影響生活質素

一般而言，哮喘患者會有以下病徵：咳嗽、痰涎、呼吸困難、氣促、胸口有壓迫感及呼吸有喘鳴等，他們在發病時支氣管因發炎加劇而變得腫脹、狹窄，積有痰液及分泌物，令空氣不能順暢地出入肺部；所以會有喘鳴及呼吸困難的病徵，嚴重者更可以因此而窒息致命。

還有，很多哮喘患者有睡眠不足的問題，除了影響他們睡眠的質素外，間接亦影響他們的日常生活或工作表現；因此，若發現自己經常有上述的病徵時，便必須及早求診，以免病情進一步惡化。

 

 

 

參考資料: www.allergy.hk

以上所提供的資訊僅作為教育及參考用途，如果你有任何醫療問題，

應向自己的過敏病科醫生查詢，而不應單倚賴以上提供的資料。

常見致敏原:動物

 

 

常見的致敏原，亦是最容易引起敏感的動物，包括貓、狗、鼠類（小鼠、大鼠、倉鼠）、馬及鳥類等，以貓致敏原引起的敏感問題最多。貓致敏原在皮脂中產生，分泌後致敏原便會留在表皮和毛髮上，當患者接觸貓的毛屑後便會出現過敏反應。

不少人以為倘若家裏沒養貓狗，便不會接觸動物致敏原，但事實並非如此。以貓的致敏原為例，因它的黏性很強，大部份貓主的衣服都會帶有貓的致敏原，並跟隨左右，散佈在學校、圖書館及其他公眾場所等。

跟塵蟎相比，動物致敏原的平均體積較小，如貓的致敏原直徑約1mm，而塵蟎則有5－10mm。這麼細小且輕的致敏原，可以在空氣中懸浮一段較長的時間，因此當患者進入貓狗的範圍內，敏感反應很快便會出現，根本不需要與動物有直接接觸。 還有，有研究發現即使在沒有養貓狗的家居中，也有機會從鄰近地區傳入並測試到家中存有貓狗的致敏原。

瑞典曾有一項研究指出，課室內的空氣存在多少貓的致敏原，是跟這班學生的家中養貓有關；換句話說，若學生對貓敏感，剛巧班中有數位同學家中養貓，該名對貓敏感的學生很大機會有較嚴重的敏感症狀。就此研究後，不少瑞典的學校紛紛把養貓與沒有養貓的學生分隔上課。

參考資料: www.allergy.hk

以上所提供的資訊僅作為教育及參考用途，如果你有任何醫療問題，

應向自己的過敏病科醫生查詢，而不應單倚賴以上提供的資料。