詳細的病例回顧顯示，愛滋病毒不能透過吐痰而傳播，且咬傷的風險亦可忽略

使用吐痰罩（防止某人吐痰或咬人的約束裝置）以保護緊急醫護人員免受愛滋病毒感染是不具正當理由的。

資料來源：邁克 .卡特；Aidsmap News；財團法人台灣紅絲帶基金會編譯

根據愛滋病毒醫學雜誌發表的研究，並沒有透過吐痰傳播愛滋病毒的風險，且咬傷的風險亦可以忽略。

一個由國際調查人員組成的團隊，對肇因於吐痰或咬人造成的愛滋病毒傳播報告進行了整合分析（meta-analysis，或稱後設分析，是指將多個研究結果整合在一起的統計方法；就用途而言，它是文獻回顧的新方法）和系統評估後，並沒有發現由於透過吐痰而傳播的病例，亦只有4例極可能透過咬傷而傳播愛滋病毒的案列。

這項研究的動機來自英國警方使用吐痰罩，係因為人們認知上認為愛滋病毒和其他血液傳播的病毒透過吐痰而傳播的風險很高。研究人員的研究結果，支持國家愛滋病信託基金和C型肝炎信託基金的立場，即無論是愛滋病毒還是C型肝炎病毒都不能透過吐痰而傳播，而警察部隊使用吐痰罩來保護執法人員免受這些病毒的威脅是不具正當理由的。

該研究的作者解釋說：「我們對與咬傷或吐痰有關的愛滋病毒傳播進行了系統的文獻回顧，以確保未來有關於咬人和吐痰事件的對應政策和做法，係根據當前的醫學證據所提供之信息而做決定。」

他們鑑定了已發表的研究和研討會報告中，報導了透過吐痰或咬人傳播愛滋病毒案例。納入分析的標準為：文章係討論透過咬傷或吐痰而造成傳播，且其結果描述包含HIV抗體檢測記錄。在整體分析中的各個研究係由兩名評論員獨立地進行了鑑定。

由於這些研究中並沒有世代研究或病例對照研究，因此，研究人員乃根據愛滋病毒狀況的基本資料、傷害的性質、事件與愛滋病毒檢測間的時序關係、以及如果能夠取得的話系統發生上的分析資料，去評估在吐痰或咬人傳播了愛滋病毒事件上的可信度。傳播與事件相關的可信度被評分為高、中或低，作者們共審查了742項之研究和病例報告。其中沒有任何一項係因吐痰導致了愛滋病毒傳播的病例被報導。

所有研究中共有13項研究報導了和咬傷相關之HIV傳播。這些研究中包含了十一起的病例報告和兩起的系列案例與愛滋病毒的傳播有關，係發生在一次咬人事件後，或者是缺席。

在英國沒有因咬人而導致愛滋病毒傳播的可能案例或係涉及緊急醫護人員之案例。

這些報告包括了23個人的信息，其中9人（39％）血清陽轉為HIV。其中六起涉及家人，三起涉及打鬥造成之嚴重創傷，另外兩起是未經訓練的急救人員將手指放入癲癇正發作的人們口中。

「在審查的742件記錄中，沒有愛滋病毒傳播病例可歸因於吐痰被報導，這支持了被愛滋病毒陽性個案吐痰不可能傳播愛滋病毒的結論」作者寫道。「儘管咬人事件的發生普遍地被報導，但只有少數病例報告顯示愛滋病毒傳播係因咬傷而繼發，這結果亦建議被HIV感染者咬傷而感染愛滋病毒的總體傳播風險可以忽略。」

極高度可能因咬傷而導致愛滋病毒傳播的案例僅有四例。在每一案例中，愛滋病毒感染者都已發病，而且沒有使用綜合性的抗反轉錄病毒藥物療法，因此可能病毒量很高。咬傷造成了深度的傷口，且愛滋病毒陽性者他們的口中都有血。

研究人員指出：「在癲癇發作的情況下發生了兩起事件，一名未經訓練的急救員在試圖保護被搶救人員的氣道時被咬傷」 。 「因此，重要的是緊急醫護人員和急救員都應接受癲癇發作安全處理方面的培訓，包括非侵入性氣道保護並採用普遍全面性的防護措施」。

調查人員強調，他們沒有發現任何緊急醫護人員或警務人員因咬傷而感染愛滋之病例。他們指出，咬傷是進入意外和急診科部門常見的原因：在英國一項針對醫院因意外及急診入院的四年期的回顧調查發現，平均每三天就有一人因被咬傷而入院。

「目前英國關於PEP（接觸暴露後之預防，暴露在愛滋病毒高風險情況後的緊急愛滋病毒藥物治療）的適應症指引中聲明，『除非在很極端之情況下和與專家討論之後，不建議在被愛滋病毒陽性個案咬傷之後使用PEP』」，作者總結。  

「由人類咬傷而傳播愛滋病毒的必要條件，似乎是存在於未經治療的愛滋病毒感染、嚴重創傷（涉及皮膚穿刺傷）的存在，並且通常是咬人者口中有血液的存在。 在沒有這些條件的情況下，沒有必要投予PEP，因為沒有傳播風險。」

HIV cannot be transmitted by spitting, and risk from biting is negligible, says detailed case review

Use of spit hoods not justified to protect emergency workers from HIV

Michael Carter; Published: 08 May 2018

There is no risk of transmitting HIV through spitting, and the risk from biting is negligible, according to research published in HIV Medicine.

An international team of investigators conducted a meta-analysis and systematic review of reports of HIV transmission attributable to spitting or biting. No cases of transmission due to spitting were identified and there were only four highly probable cases of HIV being transmitted by a bite.

The study was motived by the use of spit hoods by police forces in the UK because of the perceived risk of the transmission of HIV and other blood-borne viruses from spitting. The researchers’ findings endorse the position of the National AIDS Trust and Hepatitis C Trust that neither HIV nor hepatitis C virus can be transmitted by spitting, and that the use of spit hoods by police forces to protect offices against these viruses cannot be justified.

“We undertook a systematic literature review of HIV transmission related to biting or spitting to ensure that decisions about future policy and practice pertaining to biting and spitting incidents are informed by current medical evidence,” explain the study’s authors.

They identified published studies and conference presentations reporting on transmission of HIV via spitting or biting. Inclusion criteria were: discussion of transmission by biting or spitting; outcome described by documented HIV antibody test. Two reviewers independently identified studies that were included in the full analysis.

There were no cohort or case-control studies. The investigators therefore assessed the plausibility of HIV being transmitted to a spitting or biting incident according to baseline HIV status, nature of the injury, temporal relationship between the incident and HIV test, and where, available, phylogenetic analysis.

The plausibility of transmission being related to an incident was categorised as high, medium or low.

A total of 742 studies and case reports were reviewed by the authors.

There were no reported cases of HIV transmission attributable to spitting.

A total of 13 studies reported on HIV transmission and biting. The studies consisted of eleven case reports and two case series relating to HIV transmission, or its absence, after a biting incident.

None of the possible cases of HIV transmission due to biting were in the UK or involved emergency workers. The reports included information on 23 individuals, of whom nine (39%) seroconverted for HIV. Six of these cases involved family members, three involved fights resulting in serious wounds, and two were the result of untrained first-aiders placing fingers in the mouth of an individual experiencing a seizure.

“Of the 742 records reviewed, there was no published cases of HIV transmission attributable to spitting, which supports the conclusion that being spat on by an HIV-positive individual carries no possibility of transmitting HIV,” write the authors. “Despite biting incidents being commonly reported occurrences, there were only a handful of case reports of HIV transmission secondary to a bite, suggesting that the overall risk of HIV transmission from being bitten by an HIV-positive person is negligible.”

There were only four highly plausible cases of HIV transmission resulting from a bite. In each case, the person with HIV had advanced disease and was not on combination antiretroviral therapy and was therefore likely to have had a high viral load. The bite caused a deep wound and the HIV-positive person had blood in their mouth.

“Two cases occurred in the context of a seizure whereby an untrained first-aid responder was bitten while trying to protect the seizing person’s airway,” note the researchers. “It is therefore important that both emergency workers and first-aid responders are trained in safe seizure management including non-invasive airway protection and use universal precautions.”

The investigators emphasise that they found no cases of an emergency worker or police officer being infected with HIV because of a bite. They point out that bite injuries are a common reason for attending accident and emergency departments: a review of A&E admissions over a four-year period at a hospital in the United Kingdom found that one person was admitted with a bite wound every three days, on average.

“Current UK guidance on indications for PEP [post-exposure prophylaxis, emergency HIV therapy after a high-risk exposure to HIV] state that ‘PEP is not recommended following a human bite from an HIV-positive individual unless in extreme circumstances and after discussion with a specialist,’” conclude the authors. “Necessary conditions for transmission of HIV from a human bite appear to be the presence of untreated HIV infection, severe trauma (involving puncture of the skins), and usually the presence of blood in the mouth of the biter. In the absence of these conditions, PEP is not indicated, as there is no risk of transmission.”

Reference

Cresswell FV et al. A systematic review of risk of HIV transmission through biting or spitting: implications for policy. HIV Med, online edition. DOI: 10.1111/hiv.12625 (2018).