I. Malarial Fevers.
Definition:—A form of fever, non-contagious in character, but resulting from a specific infection; marked by distinct periodic intermissions or remissions and exacerbations. There is usually splenic enlargement, with liver complications and destruction of the red blood corpuscles, resulting in anemia.
Etiology:—The disease results from the introduction into the blood of a specific microorganism, the hematozoön of Laveran, correctly termed the hemamebae malariae, better known as the Plasmodium malariae. The predisposing causes are, residence in a low, flat, poorly drained locality, near swampy or marshy land. It is more common in the early spring and late fall, and occurs more readily from outdoor exposure after sunset.
The anopheles mosquito has been proven to be the host of the Plasmodium malariae. The spores are excreted by the salivary glands of the mosquito. A mosquito that has bitten a malarial patient passes the infection on by biting a person not infected. Where malarial patients are screened from mosquitoes and where also those not infected sleep under netting, and especially where the breeding places of the mosquitoes are disinfected with crude petroleum and the marshes drained, the infection is rapidly and surely reduced. The belief that malarial poisoning is due to certain "miasms" or exhalations from swampy ground has been disproven by the fact that persons protected from mosquitoes living and sleeping for an extended period of time in such malarial territory have remained free from malaria.
Furthermore, malaria has been directly communicated by the bites of mosquitoes known to have fed upon the blood of malarial patients in a distant country, as in the experiments of Patrick Manson, in England, upon his son. Manson received infected mosquitoes from Italy, and their bite promptly communicated the disease to his son. In the blood of young Manson was found the same parasite as was observed in the patients in Italy.
The name malaria includes several varieties of fever, all from the same cause, and all characterized by periodicity. Malaria may be present in the system and not apparent until some other cause develops fever, or local inflammation, when periodicity in remissions or exacerbations of the fever appear and prove the presence of the germ, demanding treatment for its destruction.
The common manifestations of malaria are, remittent fever, intermittent fever, masked intermittent fever, pernicious malarial fever, or congestive intermittent fever and the presence of the malarial cachexia. Each of these forms of fever will have separate consideration.
Varieties:—When the three stages of the disorder follow each other in regular and immediate succession, occurring with the intermission, in each twenty-four hours, the form is called quotidian. This is the most common form. When the attack occurs only on every other day, it is called tertian, on every fourth day quartan. There are double forms of the disease. In double quotidian there are two distinct attacks each day, one in the morning and one in the evening. In double tertian, there is one chill each day, but it occurs on the morning of one day and in the evening of the next day. The double quartan occurs on two successive days, on the third day there is no attack.