Antibodies, white blood cells, the complement, and lymph cells are all made of complete protein. A lack of this nutrient can prevent recovery from infections regardless of the amounts of vitamins obtained. When a low-protein diet has been replaced by one high in protein, the production of antibodies has increased within a few hours. Of single amino acids, methionine and tryptophane, generously supplied in eggs and milk, are particularly valuable. Of single proteins tested for their ability to build body defenses, liver, yeast, and especially wheat germ proved most valuable. Egg yolk, milk, meat, and soy flour, in this order, particularly increased the production of white blood cells.

There is much more to the ear than appears on the outside of the head. That part, easily visible, if unusually prominent gives a lot of concern. In addition to the external ear, the apparatus for hearing includes the middle ear and the internal ear.

The external ear includes the portion that is on the outside and the small canal which runs down as far as the eardrum. It is a collection of skin and other tissue such as cartilage and muscle. In most human being the muscles are merely remnants of the large muscles possessed by animals, so that few people are able to move their ears with any degree of celerity or satisfaction.

The tissue which lines the eyelids and runs out over the eyeball is called the conjunctiva. An inflammation of this tissue is known as conjunctivitis. When the conjunctiva becomes inflamed there is burning and smarting of the eyelid, formation of pus, and reddened eyelids. Usually the eye when inflamed becomes exceedingly sensitive to light, and tears flood it constantly. In the morning the eyelids will be found crusted together. Doctors treat this condition according to the character of the germ that causes the inflammation and according to the severity of the infection.

The Rickettsiae are minute infectious agents, smaller than most germs and larger than most viruses. Most classifications put them midway between the bacteria and the viruses. Rickettsia are too large to pass through a bacterial filter and are visible with an ordinary microscope.

Like the viruses, they multiply only in the presence of living cells and many of them live inside living cells. They usually are transferred from animals to men by ticks, mites, fleas, or lice. Many of the rickettsial diseases of men have been identified as such only during the last fifty years. The word "Rickettsia" comes from the name of Howard Taylor Ricketts, a physician in Chicago who was one of the first to observe these organisms and determine their nature.

The streptococcus is one of the most widely distributed and variable organisms that attacks mankind. Such conditions as sore throat, sinus infections, scarlet fever, erysipelas, puerperal fever, or lymphangitis may be caused by streptococci. Other conditions associated with such streptococci include acute rheumatic fever and acute inflammations of the kidney.

Such infections are found in all races, in both sexes, at all ages, and they come on at any time of the year. Scarlet fever is said to be rare in the tropics. Very small babies, under three months of age, seldom have streptococcal infections, because they get some immunity from their mothers at the time of birth. Tonsillitis, pharyngitis, and scarlet fever are more frequent up to ten years of age. Streptococcal infections can result from contaminated food, milk, water but most frequently pass from one person to another with coughing, sneezing, spitting and what are known as "hand-to-mouth" infections.

Influenza is an acute infectious disease caused by a virus. It comes on suddenly with fever, muscular aches, chilliness, and a cough. After, an attack, serious weakness is common for some weeks. Although outbreaks of influenza have occurred for centuries only in recent years have, the different forms of virus associated with epidemics been isolated. Two forms known as influenza virus A and B have been isolated since 1933. Vaccines for inoculating against these forms have been developed but routine immunization is not advised because the uncomplicated disease is rarely fatal and because the type or nature of the virus varies from one epidemic to another.

The virus of influenza is transmitted from one person to another by droplets of fluid coughed out of the nose, throat, and lungs. An epidemic usually reaches its peak in two or three weeks and then subsides in from four to eight weeks. The worst period of the year is winter and early spring. The influenza virus seems to be constantly present among human beings and epidemics occur under the specially favorable circumstances at aid spread of the Virus and lessen resistance.

Pneumonia was once one of the most feared of all human diseases. Its death rate was about a third of all those whom it attacked. The germ that caused it is one called a "pneumococcus" which lives ordinarily in the noses and throats of anywhere from five to sixty per cent of people. The condition comes on most often in the winter months and can affect people of all ages.

The pneumococcus gets down into the lungs and there sets up a severe infection which follows a typical course. For a few days the symptoms are like those of an ordinary respiratory disease. Then comes the sudden hard, shaking chill, rapid rise in temperature and pulse rate, with a severe pain on one side of the chest that the doctor recognizes as the beginning of pneumonia. The cough comes on painfully and with small amounts of pink or rust-colored sputum. Breathing is rapid, shallow and painful. There may be blueness because the blood is not getting enough oxygen.

Infectious hepatitis is an infectious disease caused by a virus. Formerly the condition was simply called jaundice; now we know that catarrhal jaundice is produced by an inflammation of the liver resulting from an attack by the virus which is specific for that disease. Epidemiologists believe that the virus gets into the human being by two possible routes: 1) by inhaling a droplet from the throat coughed into the air by people who are infected, and 2) by consuming contaminated food or water.

A similar condition called homologous serum jaundice follows the injection of blood or serum from certain donors who harbor a virus that attacks the liver. This type of jaundice has a longer incubation period than infectious hepatitis-namely, from 50 to 140 days after the transfusion, compared to 25 or 46 days after receiving the virus by the routes previously mentioned.

Throughout history man has faced the spread of infection, pondering its causes and how to treat it or prevent it. Infections have been known to affect major segments of the population, as did the plague in the Middle Ages. Although important advances have been made in understanding and treating infection, the threat of infection looms as large as it ever has. Newer enemies in the battle of infection emerge such as HIV and hepatitis C virus (HCV). Once-conquered enemies become resistant to treatment, as it the case of Mycobacterium tuberculosis and methicillin-resistant Staphylococcus aureus. Healthcare personnel typically encounter numerous patients on a daily basis, many of whom may be harboring these or other agents of infection. Measures to prevent the spread of infection must be taken in the course of treating all patients.

By far the vast majority of instances of fever result from infection. There are, however, cases in which fever occurs and in which the exact cause cannot be easily determined. Certain principles have been established by years of experience for the handling of fever.

Rest in bed is the number one step for any person with fever. Under such conditions the work of the heart, kidneys, and liver is reduced. The sense of fatigue is lessened. The blood flow to the kidneys and liver tends to be better in the lying-down than in the standing position. The disadvantages of bed rest include: less stimulation to breathing, a sluggish blood flow in the legs, and a noticeable diminution in muscular strength. Bed rest should always be used in association with a certain amount of activity suited to the condition of the person concerned. This may involve simply encouraging him to move, turn and sit up in bed, but might include controlled exercise or even moving of the patient's limbs by the attendant nurse or member of the family. In the nursing of those with fevers, special attention must be paid to giving plenty of fluids.