VI.—Malaria

Malaria, known also under the names of ague, paludism, marsh fever, remittent fever, intermittent fever and climatic fever, among others, is a very widely spread disease. It is most prevalent in the equatorial regions and gradually diminishes north and south of the equator. The various malarial parasites (see pp. to ) are spread by species of Anophelines, and hence malaria is present in districts favourable to these intermediate hosts, that is, in places where there is a considerable amount of atmospheric moisture and rain, as well as heat.

The principal malarial parasites are: Plasmodium vivax, the agent of simple tertian fever; Plasmodium malariæ, the parasite of quartan malaria, and Laverania malariæ or Plasmodium falciparum, producing malignant tertian or sub-tertian malaria (and quotidian, see p. ). These various malarial fevers present certain clinical features in common, which will be stated here (see also pp. to 157). For further particulars regarding malaria in all its aspects the reader is referred to the book by Sir Ronald Ross on “The Prevention of Malaria,” to the “Manual of Tropical Medicine,” by Drs. Castellani and Chalmers, and to the “Tropical Diseases” of Sir Patrick Manson.

Typical malarial fevers consist of a series of pyrexial attacks which recur at definite intervals of twenty-four (quotidian), forty-eight or seventy-two hours, according to the parasite present in the patient’s blood. Each attack shows three stages, a stage of rigor, a heat stage and a stage of profuse perspiration. Following on these three stages, there is an interval relatively or actually without pyrexia. Then the fever returns again. A rise of temperature, often accompanied by a general feeling of malaise, may precede the initial stage of rigor. When the latter sets in, the patient feels intensely cold, shivers violently, the skin becomes cold and the features pinched. There may be violent vomiting and convulsive attacks in young children. The temperature, however, is really above the normal, and continues to rise. After about an hour, the shivering abates and the heat stage succeeds it. The temperature rises rapidly, even to 106° F. The patient becomes very flushed, the pulse is rapid, headache may be intense and the skin dry and burning. This stage, that causes acute distress to the patient, may last for one or often three to four hours, and then the patient commences to perspire profusely, the clothing and bedding often being saturated with sweat. After this, the fever rapidly declines, and when the sweating ceases, the patient may feel almost well although somewhat languid. The sweating stage persists from two to four hours, so that the attack lasts as a rule from six to ten hours. After an interval of one, two or three days, a recurrence takes place. During the early part of the attack, especially at the stage of rigor, there is great splenic enlargement. At first the enlargement disappears in the interval, but in the case of repeated attacks the spleen tends to become permanently enlarged. During malarial attacks and during the intermission period, there is a great increase in the amount of nitrogen excreted by the kidneys, while the excretion of iron and bile in the fæces is increased.

Stitt (1914) points out that it is characteristic of malignant tertian paroxysms that they set in with chilly sensations rather than a frank, definite chill, and that the fever is of the remittent type.

Plasmodium malariæ and P. vivax rarely produce marked lesions in the bodies of their hosts, as they sporulate in the circulating blood and so do not accumulate in any one organ. On the other hand, Laverania malariæ (Plasmodium falciparum) multiplies within the internal organs of its host, and consequently aggregates or clusters of the parasites occur therein. The organ in which most sporulation occurs suffers most. The liver is generally enlarged, soft and congested. The capsule of the spleen is tense, but the splenic consistency is less than normal. The bone-marrow is often dark and congested in the spongy bones and brownish-red in long bones. The blood-capillaries of the brain and spinal cord are often filled or blocked with sporulating parasites and large quantities of pigment are found in these organs. Even if the parasites are absent, the pigment is present in the endothelial cells. Pigment is found in most organs of the body.

Atypical forms of malaria may occur in which some or all of the symptoms are much modified. Irregular fevers also may be produced by successive infections by the same parasite, or by the presence of two different malarial parasites.

As regards the diagnosis of malaria, according to Manson the three pathognomonic signs are—periodicity, the effect of quinine, and the presence of the malarial parasite.

Treatment.—The great specific for malaria is quinine. It attacks the merozoites or asexual generation. The drug can be administered by the mouth, by the rectum, by intramuscular injections or by intravenous injections, the two latter methods being adopted in serious infections or where gastric complications are present. When quinine is taken by the mouth, the more soluble acid salts, e.g., quinine bihydrochloride and bisulphate, are better than the sulphate, the form in which quinine is usually sold. Tablets, pills and capsules are convenient means of taking quinine but must not be old or hard, or they may pass unchanged through the body. In the case of mild tertian or quartan malaria, Castellani and Chalmers recommend the administration of a dose of quinine four hours before the sporulation of the parasite is due. Another modification is to give 10 gr. of quinine by the mouth in the morning and a second dose of 10 gr. as above. In many cases they give 5 to 10 gr. of the drug three times a day. Administration of quinine per rectum may be useful but they recommend intramuscular inoculation. The solutions used must be sterile, and the “sterilettes,” small, hermetically sealed vials, containing 1 grm.) or 1/2 grm. (7 1/2 grm.) of quinine in solution, are recommended. A deep injection into the deltoid or gluteus muscle is usual.

For pernicious infections, intravenous inoculation with not less than 1 grm. at a time is recommended.

After the fever has subsided, the administration of quinine in smaller doses must be continued for some time, in order to avoid relapses.

Stitt (1914) writes that “there now seems to be a tendency to use the alkaloid itself instead of its salts, it having been found that the alkaloid and its very insoluble tannate are absorbed from the digestive tract equally as well as the soluble salts.” Euquinine or ethylcarbonate of quinine contains 81 per cent. of quinine, but is expensive.

During malarial attacks, constipation must not be allowed. Headache can be relieved by cold applications, and perspiration must be encouraged in the early stage by hot tea, warm lime drinks, etc. After bad attacks, a change to a cooler climate is desirable, but the quinine treatment must not be discontinued.

Preventive measures take two main forms, directed respectively against the malarial parasites in man, and against the mosquitoes that convey the parasite from man to man.

With regard to man, houses should be built away from low-lying marshy ground, and kept free from vegetation such as grass or brush which furnishes shelter to the mosquitoes. In the tropics, the chief reservoirs of the malarial parasites are the native children, hence European quarters should be away from native dwellings as far as possible. Mosquito nets, having twenty to twenty-four meshes per square inch, should be used invariably, and houses should be screened. Malaria-conveying mosquitoes bite chiefly towards evening. Quinine treatment for preventive purposes is important. A dose of 5 gr. of quinine daily, with a dose of 10 gr. on the seventh day (Castellani), is efficacious. Some workers, however, recommend a large dose (15 gr.) on two consecutive days every eight or ten days for three months, while others recommend 10 gr. twice a week. Celli administered 3 gr. of quinine morning and evening.

The second line of attack is directed against mosquitoes, especially Anophelines, on the lines so well set forth by Sir Ronald Ross. The accumulation of small quantities of water in various vessels, many of them unnecessary, should be prevented, as Stegomyia (Culicines) breed in such receptacles. Anophelines breed in small pools. All drinking water and household vessels, water-butts and cisterns must be effectively screened with wire gauze. Cesspools, etc., must also be screened, and they, and all collections of water, should be oiled with crude petroleum sprays every week or ten days, or fortnight according to some workers. The petroleum is a good larvicide and suffocates the Anopheline larvæ, while its presence renders the site obnoxious to the adult mosquitoes. The amount of crude petroleum or kerosene will vary according to the locality concerned, due regard being paid to its powers of spreading on the surface treated. Different authorities have used different quantities, such as 1 oz. of oil to 1 square yard or to 15 square feet. Others have used 1 pint of the petroleum to a circle of 20 feet in diameter, while 1/2 pint for every 100 square feet of surface has also been recommended. The larvicide used so successfully in Panama consisted of:—

Average mixture

Crude carbolic acid (containing 15 per cent. phenol)

300

gallons

Caustic soda

30

lb.

Resin

200

lb.

One part of this mixture in 5,000 parts of water containing mosquito larvæ destroys them within five minutes; 1 part in 8,000 of water kills larvæ in thirty minutes. Small fish, such as the “millions” fish, that feed on the larvæ, can be introduced into collections of water and are of local service. Ducks may also act as destroyers of larvæ. The growth of water-weeds and rank vegetation, that affords shelter to the larvae, must be prevented as far as possible.

Wherever possible hollows should be filled up, swamps and roads should be well drained. Much good has followed the use of such measures in Panama, Egypt, British Guiana and other places. The ideal conditions for malaria reduction appear to consist in a combination of general quinine prophylaxis with anti-mosquito measures.