Regarding the value of quinine prophylaxis amongst carriers, the results obtained at the malaria centres and camps during the war showed that any dosage under a total of 6o grains weekly proved insufficient for an adult male. Other salts of quinine, of hydrochloride and bihydrochloride, affect the digestion less and seem to be as satisfactory. The tannate has been much used in Italy, especially for prophylaxis among children. The daily small dose is more easily, and therefore more certainly, taken by patients (out of hospital) than larger occasional doses which cause some dyspepsia and headache and are therefore frequently postponed. Children can be given a larger proportion by body-weight than adults, say, twice as much. Ross has always felt that, to be ef fective, quinine should be continued in ten-grain doses daily for three months after a subject has left a malarial country.
Quinine prophylaxis has been of value on particular occasions, such as in tiding a body of troops over a critical period of fighting or passing through a heavily infected area, in that it has kept off attacks of malaria during that time. Bodies of troops in Salonika who were given quinine daily remained free as long as they were taking it, but went down with malaria as soon as they stopped it, showing they were infected in spite of it.
Not all people bear quinine continued over a long period well, and they may show symptoms of quininism. Occasionally an individual is hypersensitive to quinine and may show symptoms even following an initial dose. On the first appearance of quin inism the drug should be stopped for a time, or arsenical treat ment substituted. In the hypersensitive case some begin with very small doses to desensitise the patient. Certain investigators in the Tropics consider that it is more difficult to eliminate the parasite by quinine therapy in cases that have been taking quinine consistently and have become infected in spite of it. The cost of quinine and of its supervised administration has frequently ren dered quinine prophylaxis impracticable in certain endemic areas.
Quinine prophylaxis should be supported by measures to pre vent mosquito bites as far as practicable. In endemic areas and where there are many carriers the infection rate of the mosquito may be very high and frequent reinfection may occur.
The second measure of prophylaxis, i.e., the reduction of anopheline mosquitoes and the prevention of bites, has received more general application. This is difficult and costly, but it results in a lessened sickness and death-rate from malaria, and in profit from the expenditure incurred.
In subtropical regions or where mosquitoes hibernate in dark places in rooms of homes, cellars, stables, outhouses and such places, often attaching themselves to cobwebs, they should sys tematically be killed directly or by fumigation. The breeding place of the mosquitoes is any still water on which they lay their eggs, and to kill the larvae and pupal forms through which they pass in development is the object in view. Much can be done by the filling in of small pools, cattle foot-marks, draining of marshes, clearing out of long grass and reeds from the sides of streams, the conversion of still to running water when in large masses, the clearing away of all cans and unnecessary water containers and the covering by gauze of cisterns and tanks and the like around the homes. A female mosquito lays about 25o eggs at one time and seven to ten days bring them to maturity. The young aquatic forms may be destroyed by larvicides such as kerosene, waste oil, cresol or "paris green," which, when mixed with too parts of dust (i c.c. of the mixture to tosq. metres of water) and blown on to the water, distributed by the winds or dropped from aeroplanes, kills the anopheline larva forms and does not injure the fish or the animals that drink therefrom. Valuable agents against larvae and pupae are the surface-feeding minnows, gambusia, stickle back and perch.
Anopheline mosquitoes do not attack until sunset, when one may remain as far as possible indoors in houses, bungalows and huts protected by close-mesh wire or netted windows and double doors ; a bed or head net should cover any exposed part of the body during sleep. In the early evening the wearing of puttees by men and a paper lining under the stockings of women prevents bites on the legs. Coolie lines should be placed, when possible, a mile from the breeding places of Anopheles, though this does not mean that the mosquitoes cannot fly much farther. There is little danger to be anticipated from breeding places over a mile distant, if the mosquitoes have opportunities of feeding close at hand (i.e., from other mammals), and if the intervening space be raised, wind-swept and clear of all shrubs and trees. The knowledge that the mosquito will attack man or animal in its thirst for blood has raised certain questions regarding the preservation of game, but up to the present no practical studies on any extensive scale have been made.