MALARIA SURVEY: METHODS AND PROCEDURES 
By JOHN E. ELMENDORF, Jr. 
INTERNATIONAL HEALTH DIVISION, ROCKEFELLER FOUNDATION, PENSACOLA, FLORIDA 
A malaria survey is a quantitative as 
well as a qualitative procedure directed 
toward securing information which will 
determine the status of malaria in a com¬ 
munity. The survey should serve as a blue¬ 
print for the guidance of the malaria de¬ 
partment and it should provide an original 
base-line from which all subsequent mea¬ 
surements of the course of the disease are 
determined. 
Lists of the equipment necessary for a 
survey are given in detail by such writers 
as Boyd (1930a) and Christophers et al. 
(1936). 
The staff will depend upon the scope of 
the program, but generally speaking the 
essential personnel should be: a medical 
malariologist, who should also be the direc¬ 
tor of the group; an entomologist with spe¬ 
cial training in culicidology and the use of 
larvicides; and a sanitary engineer with 
special training in hydraulics. 
A malaria survey should include the col¬ 
lection of data on demography and inci¬ 
dence. Demographical data, describing 
for minor civil divisions the composition of 
the population by race, age and sex, may 
be secured from official censuses; but if 
data from such sources are not available, 
the investigator may be obliged to make a 
census or at least a very careful estimate. 
The incidence of malaria in a population 
cannot be exactly determined. Morbidity 
reporting, so useful in many lines of prac¬ 
tical epidemiology, has undeveloped pos¬ 
sibilities as applied to malaria. At present, 
however, the utility of available reports is 
slight, even where competent medical ser¬ 
vice is conveniently available, because the 
diagnosis of malarial infection is often not 
made with precision. Moreover, many in¬ 
fected persons do not consult a physician 
during their attacks. Furthermore, many 
states accept totals of cases purportedly 
seen without requiring the particularized 
identifying data so essential in epidemio¬ 
logical inquiries. Consequently, the mala¬ 
riologist is usually obliged to gather his 
own data. 
A malariologist with proper apprecia¬ 
tion of his problem of diagnosis will limit 
himself to the collection of objective data, 
significant in relation to the existence of a 
malarial infection. Unfortunately, there 
is not available at present any single in¬ 
fallible criterion by which malarial infec¬ 
tion may be recognized. Comparatively 
few persons encountered in the course of 
a survey may be acutely ill at the time. 
The detection of parasites in a blood smear 
is incontrovertible evidence of the existence 
of infection, but in many persons with 
chronic and latent infections the parasites 
may, at the time when a blood smear is col¬ 
lected, be at submicroscopical levels, and 
hence undetectable. Malarial infections 
invariably produce some degree of sple¬ 
nomegaly, which may persist when the 
infection becomes chronic, particularly in 
inadequately treated persons. While other 
infections may also produce acute enlarge¬ 
ment of the spleen, these subside quickly. 
Therefore in most communities, where 
other acute infections have not recently 
been epidemic, the presence of any number 
of persons with splenic enlargement may 
be significant from a malarial standpoint. 
If enlargement is due to malaria, these per¬ 
sons will usually show a significantly 
^higher proportion with parasites in their 
blood than will be found in those with nor¬ 
mal spleens. Furthermore, considerable 
variation in the size of different enlarged 
spleens will be observed. For a considera¬ 
tion of other aspects, including the effect 
of race, etc., the reader is referred to Boyd 
(1930a). 
Since it is usually impracticable to 
