2009年2月23日 星期一

Another Dimension in Emerging Infectious Diseases

Fantastic Voyage: Influenza

by Julian W. Tang
in Emerging Infectious Diseases, 15 (3):512, 2009 (March)

2009年2月10日 星期二

WA expertise used in dengue vaccine trial

ABC News
Posted Mon Feb 9, 2009 10:52am AEDT

Health authorities in the United States will soon begin world first human trials of a vaccine for dengue fever.

A Perth-based drug company has been working with scientists in Hawaii to develop the vaccine.

Dr William Ardrey hopes the vaccine will be available in the next two to four years.

He says they will use the trials to test how many vaccines are needed and how much time should be left in between injections.

"Vaccine trials are pretty interesting because you know pretty soon whether the vaccine does or doesn't work," he said.

"What you're trying to do is challenge the patient's immune system and you can actually measure immunity, so you can tell whether these sorts of vaccines work pretty soon on."

Dr Ardrey says the scientists have manufactured a protein in the dengue virus which tells the body to develop an immunity to the disease.

"It's the latest technology where you actually find the proteins that are involved in this particular virus and challenging the immune system through this particular protein," he said.

"So you're not dealing with the actual virus itself. It's a much safer way of doing things and it's a technology that upscales.

"We can make very large amounts very very quickly, both for Australia and developing countries."

Confirmed cases of the disease in Cairns, in far north Queensland, have risen to 277 and 47 in Townsville.

Authorities say the dengue fever epidemic has also spread to the town of Port Douglas, north of Cairns.

The Cairns City Council is also treating mosquitoes in dengue prone areas in Port Douglas.

The company has spent 10 years developing the vaccine with scientists in Hawaii.

They are working with Professor Ian Frazer - who created the cervical cancer vaccine - and hope to get the vaccine into the market in the next two to four years.

The first human trials will start in the United States soon.

Key discovery made in fight against bird flu

By Caleb Hellerman
CNN Senior Producer
updated 1:08 p.m. EST, Thu February 5, 2009

(CNN) -- Two teams of scientists say they have found a key area of the H5N1 bird flu virus which seems to be vital to its ability to copy itself, and hope the discovery could lead to new drugs to fight the infection.

Human-to-human transmission of avian flu is rare, but in some cases, the virus has passed from poultry to humans.

The discovery is generating excitement among scientists who are looking for a new weapon against the bird flu virus that typically kills more than half its human victims.

Two separate groups of scientists -- one in China, one in France -- used a highly technical process to identify protein that seems to be involved in its ability to replicate itself.

That gives researchers a new target, as they try and develop new medications.

The announcements, detailed in the British-based journal Nature, come at an uneasy time for those who follow the bird flu strain called H5N1.

So far this disease is mainly affecting birds in some countries and the number of human cases remains small, but the virus has shown no sign of growing milder since it first infected people back in 1997.

It continues to decimate bird flocks in sporadic outbreaks, mostly in Asia, and occasionally breaks into the human population. China's Ministry of Health reported eight human cases last month, including four deaths.

Since 2003, the World Health Organization has confirmed 404 human cases worldwide. Nearly two-thirds of the victims have died. While H5N1 doesn't make headlines the way it did in 2005, health officials say the continuing severity of the infections means the alarm is still on.

Influenza viruses, in general, spread easily. If H5N1 were to acquire the genetic ability to pass easily from person to person, it could turn into a major catastrophe.

Many countries have stockpiled both vaccines and antiviral medications, for such a scenario. The same medications that are used to treat regular flu, oseltamivir (Tamiful) and zanamivir (Relenza), also seem to be effective against H5N1. But that's no reason to rest easy.

All flu viruses tend to mutate rapidly, which is why the flu vaccine one year, won't protect you against the next year's flu. Those rapid mutations mean the virus tends to develop a resistance to any widely used medication.

Dr. Anthony Fauci, Director of the U.S. National Institute of Allergy and Infectious Disease, told CNN, "It always happens that eventually, sooner or later, the [flu] virus will develop varying degrees of resistance. You just hope that it's kept to a minimum."

The findings in Nature may lead to another option to fight bird flu, but an actual new drug is years away. A vaccine could be effective, but they first have to know what strain of flu they're fighting.

The current strategy of health officials around the world is to try to contain isolated cases before they spread. The best case scenario would be, that this H5N1 killer remains primarily a disease for the birds.

2009年2月9日 星期一

醫生:第二階段最關鍵‧染骨痛熱症未必發病

星洲日報‧2009.01.23

(雪蘭莪‧八打靈再也)感染科會診醫生陳連發指出,骨痛熱症是由登革病毒(Dengue Virus)感染所引起,不是所有感染者都會發病。沒發病的感染者(Silent Infection)雖然毫無症狀,仍有可能通過蚊蟲把病毒傳播他人。 陳醫生說,發病的感染者所呈現的登革熱症狀,在大馬俗稱為骨痛熱症。

骨痛熱症分2類型

他說,骨痛熱症共分作兩大類型,第一類型屬於典型骨痛熱症(Classic Dengue Fever),病情一般較為輕微。 第二類型則是嚴重的骨痛溢血症(Dengue Haemorrhagic Fever),這一類型病人必須特別注意的並非只是溢血症兆,而是發病第二階段關鍵期(Critical Phase)的毛細血管血漿泄漏或滲透(Capillary Plasma Leakage)的現象,因為嚴重的血漿泄漏會導致骨痛熱休克綜合症(Dengue Shock Syndrome)以及死亡。 根據衛生部在1月16日發出的數據顯示,2009年第一週,全國11個州屬骨痛熱症案例明顯上升。 《星洲日報》走訪感染科會診醫生陳連發,讓讀者更瞭解骨痛熱症,進而作出適當的防治措施。

第二階段最關鍵

在感染科領域工作超過10年的陳醫生指出,一般感染嚴重型骨痛熱症的病人,會經歷三個階段。其中第二階段是最關鍵的。 他說,第一階段病者通常會發熱、肌肉酸痛、骨頭疼痛、沒有胃口、作嘔,有者會肚泄、皮膚出現紅疹等現象。


但是,當患者發燒進入第3至第6天左右,一般熱度開始緩解,白血球以及血小板開始有明顯下降趨勢,這時即會進入第二階段的關鍵期。他指出:“在這個階段,要注意的是毛細血管血漿泄漏或滲透(Capillary Plasma Leakage)的現象;血漿過度泄漏到肺腔或腹腔時,將引起呼吸急促,腹部腫脹、作嘔或嚴重嘔吐、腹部疼痛等症狀,這時患者血容量降低(Hypovolemia),血壓下降以至進入休克的狀態,這將影響血液循環系統的功能,導致各器官逐一衰竭,隨後體內出現大量溢血現象。”

“如果發熱病人持續嘔吐、腹部疼痛或暈眩,尤其站立時感到特別暈眩(Postural giddyness)等,必須馬上到醫院尋求緊急治療,因為這大有可能是嚴重的血漿泄漏導致血容量降低的危險訊號。” 陳醫生說,要鑒定病人是否開始出現血漿泄漏,醫生通常會參考病人的血濃度(Packed Cell Volume(PCV)或Haematocrit(HCT))而不是血小板指數(Platelet Count);血濃度提昇的越快則血漿泄漏越嚴重。

確保補充足夠水份

“這個階段的患者要確保補充足夠水份流液,讓血液循環系統的容量充足,不會出現低血容量低血壓的現象。”陳醫生如此建議。 他指出,需要補充的不單是水份,患者必須攝取足夠的電解質和營養能量。因此只是喝大量的水是不正确的,患者也需攝取其他容易消化吸收的流質食物,包括果汁、粥水、薏米水、椰水等。但是,攝取這些流液來補充體內水份流液時,糖尿病患必須注意糖份的攝取,避免血糖控制惡化。

第3個階段是復原期,進入第3個階段之後患者會開始感覺良好,胃口回轉,血小板會隨著白血球開始回升,血漿泄漏現象不再。 他指出,這個階段的患者反而需要減少喝水,因為在這階段的病人身體會開始慢慢吸收之前泄漏身体內腔的血漿,過度補充水份將導致肺積水,引起呼吸困難。

發燒3天不退速求醫

陳醫生建議公眾一旦發燒3天或以上沒有退燒,就應該即行求醫,尤其是在骨痛熱症疫區。如果患者還能適度喝水、進食,那麼向普通醫生尋求診治即可。但如果有持續腹部疼痛、嚴重嘔吐的現象,則不宜浪費時間,要直接到醫院去尋求急診。

陳醫生說,目前國內有兩種快速檢測法:骨痛熱NS-1病原體檢測(Dengue NS-1Antigen Test)及骨痛熱IgM抗體檢測(Dengue IGM Antibody Test)。在感染骨痛熱病毒初期,也就是發熱期,骨痛熱NS-1病原體檢測能及早診斷感染,但是此檢測的敏感度並不是百分之百。骨痛熱IgM抗體檢測雖然敏感度較高,但無法在患者發熱初期確定感染,因為需要等到病人體內的抗體達到一定水平後才呈陽性反應,一般這要等到患者進入恢复期才較明确。

清理清水防蚊蟲滋長

“清水是黑斑蚊滋生的溫床,要徹底防範骨痛熱症的蔓延不能單單依靠噴射蚊霧,還需把家裡積儲的水都倒掉。”感染科醫生陳連發在接受《星洲日報》專訪時如此表示。

陳醫生表示一般公眾因為先入為主,常常以為溝渠積水等,是比較需要清理的,其實黑斑蚊最愛的是乾凈的水。他呼吁公眾響應衛生部的每週花10分鐘的時間清理周遭環境的積儲的清水。

陳醫生指出,尤其農歷新年來臨之際,很多人會返鄉。此時更會有大量的流動性人群從流行疫區(特別巴生河流域)返回各自的家鄉,疫區將因此擴散,這個時侯,清理清水的動作刻不容緩。

(畢業於國大的陳連發醫生,目前是感染科會診醫生)