INFECTION is the invasion of the body by parasitic microorganisms, with or without the production of disease. The infective microorganisms may be bacteria, viruses, rickettsiae, fungi or protozoa. Very often these organisms inhabit the body without causing illness, a condition known as the “carrier state.” Healthy people who are carriers may shed the organisms, which when picked up by people with weaker defenses, produce disease. Among the organisms that may be dispersed in this manner are those that cause typhoid fever, poliomyelitis, and cerebrospinal meningitis.

感染是寄生的微生物对身体的入侵，有的会产生疾病，有的不会产生疾病。有传染性的微生物可能是细菌、病毒、立克次体、真菌或原生生物。通常这些微生物寄生在身体内不会引发疾病，一种被称为“携带状态”的条件。但携带病毒的健康人会散播这些生物体，当抵抗力弱的人感染时就会生病。在可能以这种方式散布的生物体中是那些引起伤寒、脊髓灰质炎以及脑脊髓脑膜炎的生物体。

Entry and Spread of Organisms. Microorganisms may enter the body in several ways. They may be inhaled, swallowed in food or drink, or picked up through a break in the skin or the mucous membranes. Sometimes they are introduced through the bite of an infected insect or through the prick of a contaminated needle or splinter.

生物体的进入与传播。微生物会以几种方式进入身体。它们会被吸入，会以饮食的方式吞食，或者通过皮肤伤口或黏膜传入。有时，它们会通过被感染的昆虫叮咬或者通过受到污染的针或碎片传入。

Both the method of entry and the toxicity (strength) of the microorganism help determine how it spreads and the kind of condition that results. For example, when staphylococcal bacteria enter the skin through an injured hair follicle, they remain in the area, multiply, and produce a boil. When these or streptococcal bacteria invade a slightly larger area of skin, they may produce a diffuse inflammation of the skin. If the bacteria are highly toxic and invasive, they may enter the lymph vessels and be swept into the lymph glands. Extremely invasive organisms will then be conveyed by the lymphatic system to the bloodstream, which will carry them to other parts of the body. This generalized kind of infection is known a septicemia.

进入的方式和微生物的毒性（强度）都会帮助确定它是如何传播和导致疾病的类型。例如，当葡萄球菌的细菌通过受伤的毛囊进入皮肤时，它们停留在该区域，繁殖并产生皮下脓肿。当这些或链球菌所导致的细菌侵入皮肤更大的区域，它们就可能对皮肤产生弥漫的炎症。如果细菌是高毒性和侵袭性的，它们就可能进入淋巴管，并进入淋巴腺。那么，极度具有侵袭性的生物体就会被淋巴系统传入血液循环，就会将它们带到身体的其它部分。这种广义的感染就被称为败血症。

The ability of organisms to invade body tissues is enhanced by their production of certain enzymes that break down tissue barriers. Many bacteria produce hyaluronidase, an enzyme that disrupts hyaluronic acid, an important constituent of connective tissue. Streptokinase, which is produced by streptococcal bacteria, initiates the dissolution of coagulated blood plasma, removing another natural block to invasion.

生物体侵入身体组织的这种能力是受到它们产生的某种突破组织屏障的酶来增强的。许多细菌都产生透明质酸酶，一种扰乱了透明质酸，重要的构成结缔组织的酶。链激酶，是由链球菌所导致的细菌产生的，它启动了凝固血浆的溶解，消除了另一个天然屏障侵入的。

Once established in the body, some bacteria do not spread, but produce disease by manufacturing toxins (poisons), which are carried by the blood to other parts of the body. Tetanus bacilli that enter the body through puncture wounds secrete a toxin that attacks the brain and spinal cord. Other bacteria release toxins only when they are destroyed

一些细菌一旦在身体内建立并不会传播，而是通过制造毒素（毒物）来产生疾病，它们是由血液携带到身体的其它部分。通过刺伤进入身体的破伤风杆菌分泌一种毒素，攻击大脑和脊髓。而其它的细菌在它们被摧毁时才释放毒素。

Natural Defenses and Treatment. The body is protected against infection by a number of mechanisms. Mechanical barriers, such as the skin or tissue clots, are helpful in preventing the entry of many organisms. Once inside the body, the microorganisms may be engulfed and destroyed by white blood cells and other specialized cells. In the blood and body tissues, certain complex substances, known as antibodies, destroy many of the organisms or neutralize their toxins.

自然防御与治疗。身体是通过大量机制来防止感染的。机制屏障，如皮肤或组织凝块，有助于防止许多生物体的进入。生物体一旦进入身体内部，微生物可能被吞噬，并被白细胞和其它专门的细胞摧毁。在血液和身体组织中，被称抗体的某些复杂物质，消灭了许多生物体或中和了它们的毒素。

A wide variety of antibiotics and other drugs are effective in treating many infections, especially those caused by bacteria and some rickettsiae, fungi, and protozoa. Antitoxins, substances that neutralize bacterial toxins, are available for tetanus, diphtheria, and botulism. Unfortunately, there are very few drugs known to be effective in treating viral infections.

很多抗生素和其它药物在治疗许多感染时都很有效，尤其是那些由细菌和某些立克次体、真菌以及原生生物引发的疾病。抗毒素，中和细菌毒素的物质，对破伤风、白喉以及肉毒中毒都很有效。遗憾的是，在治疗病毒性感染时，已知的有效药物却很少。

                                                                             IRVING SOLOMON, M.D.

                                                              Mount Sinai School of Medicine, New York

                                                                              欧文·所罗门，医学博士

                                                                               西奈山医学院，纽约

                                                                        2022年4月23日译

（译者注：该词条位列《大美百科全书》1985年版，第15卷，第149页）