>>>but the study did say that Leishmania was being used because it was a good model, which I took to mean it can possibly be applied to many other parasites.
They are studying Leishmania and the immune system- in scientific words that most people will never understand.
"Leishmania infection is one the best elucidated models **for studying defense mechanisms in murine macrophages.**
>>>I recalled someone on here say it was good against the effects of ammonia on the brain. I try to look up everything before I use it now because I have been badly burned before.
Then do your own researching about ammonia, because there's plenty of information that is important, and more understandable- not something you are trying to guess at what it is saying, and making assumptions.
If you are a living, breathing, eating, human being - your body is processing Amino acids- including the Arginine/Ornithine.
If you don't have a healthy liver, --(which 9/10th's of us here probably have compromised liver's) , plus have parasites, bacterias, fungi, herpes family viruses, lymes etc...you will have excessive ammonia (hyperammonemia).
My liver has been sick for a long time, and this is the key, important, piece that I'm sure I have been over-looking. I knew about it, I just didn't consider it important for myself at this point, because I haven't had the insomnia, anxiety, & brain-fog most everyone associates with the ammonia/parasites. I have also had no sign of the larger, visible parasites
for 4-5 months now, (after killing a big load of them for 14 months) and they have not shown up in biofeedback testing. I will never "assume" I am clean, and done with them. The ND will continue to muscle test me for them too. But, I made a very wrong assumption on my part- because having a sick liver, with any pathogens= ammonia. The toxins can also remain after the pathogens are gone.
****Ornithine helps remove toxic ammonia from the liver, and may reduce the effects of cirrhosis of the liver and disorders associated with liver malfunction. In one study, participants taking 18 grams of ornithine aspartate for two weeks showed significant improvement in blood tests and liver function compared to the placebo group.***
Research has also shown that ornithine helps promote healing and tissue repair. Clinical studies reported that taking 10 grams of ornithine alpha-ketoglutarate (OKG) each day helped reduce the length of hospital stays for those recovering from surgery, generalized infections, cancer, trauma, and burns.***
There are many more people that have herpes family viruses than are aware of them (including Epstein Barr, Cytomegalovirus, Shingles etc) Dr's just label it "Chronic Fatigue".
Newport already said it- the article also states it.
" Individuals with herpes and other viral infections should not take arginine supplements, because arginine seems to promote the viral growth."
I'm not promoting using the combo of Arginine/Ornithine, for that reason that a large percentage of people will have the viruses that they aren't aware of. But it is clear information about the importance- and the conversion process of the Amino's.
Arginine is a vitally important amino acid that has been studied for more than fifty years. Amino acids are the building blocks of protein, and protein is the building block of all living cells. The greatest portion of human body weight, after water, is protein.
A healthy liver can produce approximately 80 percent of the body's required amino acids. They are termed the "nonessential" amino acids, not because they lack importance, quite the contrary, but because the body can synthesize them from other amino acids obtained from dietary sources. The human body, for example, can readily synthesize arginine to ornithine, or ornithine to arginine.
The remaining 20 percent of amino acids required by humans are termed "essential" amino acids because they cannot be manufactured by the body and must be obtained from dietary sources. The body's ability to synthesize the nonessential amino acids such as arginine, and to utilize all amino acids, can be adversely affected by an individual's advancing age, overall health, organ health, the presence of infection, physical trauma such as injury, effects of stress, compromised nutrient absorption capacity, and imbalances of other nutrients.
Signs of Deficiency. Deficiency produces symptoms of muscle weakness, similar to muscular dystrophy.  Arginine-deficiency impairs insulin production, glucose production, and liver lipid metabolism.  Conditional deficiencies of arginine or ornithine are associated with the presence of excessive ammonia in the blood, excessive lysine, rapid growth, pregnancy, trauma, or protein deficiency and malnutrition. Arginine deficiency is also associated with rash, hair loss and hair breakage, poor wound healing, constipation, fatty liver, hepatic cirrhosis, and hepatic coma. 
Food Sources. Dietary arginine is found in chocolate, wheat germ and flour, buckwheat, granola, oatmeal, dairy products (cottage cheese, ricotta, nonfat dry milk, skim yogurt), beef (roasts, steaks), pork (Canadian bacon, ham), nuts (coconut, pecans, cashews, walnuts, almonds, Brazil nuts, hazel nuts, peanuts), seeds (pumpkin, sesame, sunflower), poultry (chicken and turkey light meat), wild game (pheasant, quail), seafood (halibut, lobster, salmon, shrimp, snails, tuna in water), chick peas, and cooked soybeans. [2, 11]
Arginine is involved in the production of variety of enzymes and hormones. Arginine facilitates the release of HGH, stimulates the pancreas for insulin production, and is a component in the hormone vasopressin produced by the pituitary gland.  One mechanism for arginine as an HGH releaser may be its capacity for blocking secretion of the HGH-inhibitor: somatostatin. 
HGH-release by means of arginine may offer benefits in the treatment of fractures and injuries, as well strengthening the immune system, building lean muscle, burning fat, and reversing many of the effects of aging. 
The elderly respond to arginine with substantially increased levels of glucose and growth hormone.  A study at the Division of Endocrinology at the University of Turin involving normal adults aged 66-82 who tripled the level of HGH in their blood after administration of 30-gram injections of arginine. [4, 8]
Arginine is essential for optimum growth and in the regulation of protein metabolism.  The main source of energy for muscle and other cells is glucose, but glucose metabolism produces ammonia, which is toxic unless rapidly converted to another compound. The primary metabolic role of arginine is in stimulating the enzyme that starts the urea cycle, which converts ammonia into a less toxic compound called urea that the blood carries to the kidneys for excretion.
As a cholesterol fighter, a high ratio of arginine-to-lysine is recommended.  In the urea cycle, citrulline is a precursor of arginine, so it may be that foods rich in citrulline (onions, scallions, garlic) lower cholesterol because the citrulline is converted to arginine in the body.
As a booster of the immune system, arginine stimulates the thymus and promotes lymphocyte production. [9, 10] This may be the key to arginine's ability to promote healing of burns and other wounds. During stress (good or bad), the thymus gland typically shrinks, and sickness results; however, arginine facilitates the maintenance of the gland's proper size and normal production of lymphocytes. 
In support of brain function, arginine is believed to serve as a precursor to nitric oxide (NO), a neurotransmitter. . Nitric oxide plays a role in the dilation and constriction of small blood vessels in brain. Therefore, arginine may have a positive effect on cerebral circulation. Arginine pyroglutamate is cited for having cognitive-enhancing effects. 
Related to its neurotransmitter function and its role as a precursor of NO, L-arginine has been noted for its critical role in stimulating healthy sex drive and enhanced sexual performance in men. 
In summary, L-arginine is one of the most powerful tools in any anti-aging program because of its functional value in promoting the production of HGH and other hormones, strengthening the immune system, improving lean muscle mass and reducing fat, regulating several vital metabolic processes, improving cholesterol profiles, supporting brain function, and enhancing sexuality. Hundreds of studies have been undertaken to date, and clearly arginine merits further research.
Arginine is a nonessential amino acid, which means that it is manufactured from other amino acids in the liver; it does not have to be obtained directly through the diet.
Arginine is required for proper elimination of urea from the body. This occurs through a critical metabolic cycle which detoxifies the body of nitrogen compounds that are manufactured in the liver or by intestinal bacteria action. Subtle impairments of the liver's function can often lead to subclinical symptoms of hyperammonemia, which is the condition of poor excretion of urea. Symptoms of hyperammonemia may include chronic fatigue, headache, irritability, occasional diarrhea or nausea, lack of concentration, mental confusion, and intolerance to various foods, particularly high-protein foods.
Deficiencies of a nonessential amino acid will not occur if a well-balanced diet is consume because the intake of proper foods will allow the body to produce exactly the amount of amino acid required to function optimally.
Arginine is useful in some individuals as a supplement to help treat the symptoms of hyperammonemia if they have a block in the proper metabolism or synthesis of arginine in the liver. Arginine in dietary protein is important in establishing the quantity of cholesterol to be synthesized by the liver.
Arginine is also useful for enhancing the function of the thymus gland in animals. The thymus gland is important in the promotion of proper function of the immune system. Animals given supplemental doses of arginine were found to have enhanced thymus activity with increased white blood cell response to infection. Arginine has been used therapeutically to lower blood ammonia levels in individuals who have an inability to properly manufacture urea. It has also been used as a potential immune stimulant in individuals with suppressed immunity. Safe doses of arginine can range from 500 to 2000 mg per day.
Arginine is a contributing member of the various amino acids found in the urea cycle, which is responsible for detoxifying ammonia. Ammonia is a by-product of bacterial metabolism in the intestinal tract and must be detoxified in the liver.
The urea cycle is also responsible for eliminating other catabolic sources of nitrogen so the body does not build up toxic nitrogen metabolites. In 1932, H.A. Krebs and K.Z. Henseleit noted that liver slices were capable of forming urea by a cyclic process in which the amino acid ornithine was first converted to citrulline and then to arginine. The ultimate cleavage of arginine produces urea and regenerates ornithine.
This cycle is dependent upon enzymes called transaminases, which require vitamin B-6 (pyridoxine) for their activity. It has also been found that zinc is a very important trace element that activates the urea cycle, and oral zinc therapy has been used to treat patients that are suffering from hyperammonemia. The urea cycle is also dependent upon the proper conversion of glutamate to glutamine. These amino acids have been used in therapy to facilitate more rapid elimination of ammonia. Human adults excrete approximately 20 grams of urea per day. If this rate decreases, ammonia accumulates in the blood to toxic levels. Normally, blood ammonia is very low (0.5 mg/l). Only two to three times this level is required to produce toxic symptoms, including memory loss, psychosis, tremors, and inability to concentrate.
It has recently been found that there are a number of hereditary enzyme deficiencies that affect the urea cycle, producing hyperammonemia. Many of these conditions are non-lethal, but are associated with psychiatric complications. Over twenty different types of these problems have been observed. A common feature of all these defects of the urea cycle is an intolerance to high-protein diets and the relationship of mental symptoms to elevated protein in the diet.
Toxic accumulation of ammonia in the blood is also seen in alcoholic liver disease and may account for some of the delirium tremen symptoms. It has also been found that ammonia can accumulate in the blood as a consequence of intestinal stasis and a "toxic bowel" reaction. In all of these cases, a lower-protein diet; selected supplementation with arginine, ornithine, or citrulline; or supplementation with zinc, vitamin B-6, or vitamin C may be desirable.
Arginine is also the precursor to creatine, which is ultimately converted to creatinine. This is a compound of special importance in muscle. Creatine phosphates serves as an energy buffer for muscular contraction.
Individuals who are undergoing muscle wasting have increased creatine spill in their urine. The urea cycle enzymes are also closely related to the transsulfuration pathway involving S-adenosyl methionine. This pathway is dependent upon adequate dietary intake of the essential amino acid methionine. Insufficiencies of the sulfur amino acids can, therefore, have an adverse impact upon the proper metabolism of arginine and ornithine to creatinine, and may adversely effect muscle contraction.
It can not be assumed that it is talking about all parasite
infections, that's not what the article is about.
>>>Leishmania infection is one the best elucidated models for studying defense mechanisms in murine macrophages.