24 
MALARIA 
ysms, regularly produces gametocytes, and 
relapses are decidedly infrequent. 
U. S. Public Health Service strain of P. 
malariae. This strain was isolated in May, 
1932, from a young seaman, a resident of 
Monroe, Louisiana, who was a patient at the 
U. S. Marine Hospital in New Orleans. 
This strain has been under continuous ob¬ 
servation at the South Carolina State Hos¬ 
pital where up to December 1, 1940, it has 
been passed through 57 continuous serial 
transfers and 418 patients, by direct blood 
inoculation. Most of these patients were 
colored paretics, although the strain is also 
used on the white service. In patients of 
normal temperament and habits this strain 
is generally synchronous (Young, Stubbs, 
and Coatney 1940). In colored patients it 
usually produces 25 to 30 paroxysms or 
more and relapses are infrequent. The in¬ 
cubation period, using 5 cc. of blood with a 
moderate number of parasites, is approxi¬ 
mately three weeks. Patients infected with 
this strain who experience 15 to 20 parox¬ 
ysms acquire a relatively high immunity to 
reinoculation with the same strain; to date 
the heterologous immunity has not been 
tested. 
This strain was shown to produce 3 per 
cent infections in A. punctipennis (Mayne 
1932); Boyd (1940b) also reports success¬ 
ful transmission by A. quadrimaculatus. 
During the eight years this strain has been 
under observation at the South Carolina 
State Hospital, it has continued to produce 
gametocytes, and there has been no appar¬ 
ent change in virulence. Dr. G. C. Branch 
of the Veterans Administration, Tuskegee, 
Ala., obtained this strain from our labora¬ 
tory in November, 1932. In a personal 
communication of December 2, 1940, he 
states that the strain is still maintained and 
has been carried through 62 consecutive 
passages by blood inoculation involving ap¬ 
proximately 600 patients. Branch (1940) 
reported that this strain was no longer pro¬ 
ducing gametocytes. However, infected 
blood obtained from him in the summer of 
1940 and inoculated into patients at this 
hospital produced typical infections with 
gametocytes. 
This strain was sent to the New Jersey 
State Hospital, Greystone Park, N. J., in 
June, 1934, where it has been used thera¬ 
peutically ever since. Dr. C. M. Sagert of 
that institution reports in a personal com¬ 
munication that up to December 1, 1940, 
it had been grown in 355 patients. 
Jones strain of P. malariae. This strain 
was isolated from a colored patient at the 
Florida State Hospital in the spring of 
1932. Boyd (1940b) reports the successful 
passage of this strain through two complete 
human-anopheline cycles. From one pa¬ 
tient in the first mosquito series the strain 
has been propagated artificially through 18 
serial passages, involving 29 patients. 
The Long strain of P. falciparum was 
obtained from a colored patient at the 
Florida State Hospital in 1935 and has been 
maintained in both negro and white pa¬ 
tients at that institution since that time. 
Boyd and Kitchen (1937e) report that this 
strain has an intrinsic incubation period, 
after mosquito bites, of 9 to 13 days, with 
a special predeliction for 11 days, while his 
(Boyd) Coker strain had limits of 6 to 25 
days. According to Boyd (1940a) the Long 
strain has been carried through 19 consecu¬ 
tive human-anopheline passages. Also, 
Boyd tested this strain immunologically 
against the Cuban, Mexican, and Pana¬ 
manian strains by inoculating these strains 
into Long strain convalescents and the Long 
strain into the convalescents of the other 
strains; he found the Long strain to be im¬ 
munologically different from any of the 
others tested. 
The above reports show that there are 
several well established strains of human 
malaria in this country. In addition, there 
are certain lines under observation which, 
with further study, will undoubtedly prove 
to be definite strains. 
