Q¨
UESTII ´
O, ol. 22, 2, p. 365-378, 1998
ANALYSIS OF SURVEY DATA INVESTIGATING
THE MALARIAL ENDEMICITY OF A MIXED
TRIBAL POPULATION OF BIHAR, INDIA
T.K. BASU
S. GANGULY
S.K. SARKAR
Indian S a is ical Ins i u e
R. ARNAB
Uni e si y o Du ban
A sec ion o he mixed ibal popula ion o he Singhbhum dis ic , Biha ,
India is decla ed mala ia epidemic zone. The ibal popula ion o se e al
gene a ion is known o be su e ing om mala ia. A su ey based on c oss-
sec ional da a analysis, was conduc ed on he mixed ibal popula ion o
one mon h. The pu pose o his s udy was o in es iga e he heal h s a us
using collec ed blood samples. The main ocus is on he compa a i e oles
o he «de ense mechanism»and « i ali y ac o »o he human sys em in
con ex o he mala ial in ec ion. By g adual elimina ion o he blood pa a-
me e s by s a is ical analyses, he « i ali y»pa ame e s p obing mala ial
endemici y a e assessed wi h a iew o p edic ing he epidemic.
The main indings om his su ey a e (i) o he selec ed wen y wo pa-
ame e s o blood, albumin, o al choles e ol, o al p o ein, β-Globulin, γ-
Globulin, Immuno globulin G seem o ha e some p edic i e capaci y wi h
espec o he mala ial endemici y o he ibal people and (ii) Ca ego ical
a iables like blood g oups and sex a e compa a i ely less impo an o
p edic ion o mala ia.
Keywo ds: Vi ali y ac o s; de ense mechanism; wo-way Ano a; disc i-
minan unc ion.
Biome y Resea ch Uni . Indian S a is ical Ins i u e. 203 Ba ackpo e T unk Road. Calcu a 700 035,
India.
Depa men o S a is ics. Uni e si y o Du ban, Sou h A ica.
– Recei ed Janua y 1997.
– Accep ed No embe de 1997.
365
1. INTRODUCTION
The Indian Council o Medical Resea ch, a leading medical esea ch conce n o India,
iden i ied a ew illages o ibal habi a o he Singhbhum dis ic o Biha (India)
as a mala ial epidemic zone. The people o hese illages show e idence o mala ial
su e ing o se e al gene a ions. A s udy was unde aken o in es iga e he mala ial
endemici y by checking he blood samples ob ained om a mixed ibal popula ion
o he Singhbhum dis ic . The in es iga ion was execu ed by he Indian Council o
Medical Resea ch in conjunc ion wi h he Biome ic Uni , Indian S a is ical Ins i u e.
Mala ia depends upon wo p incipal ac o s- (a) i ali y and (b) de ense mechanism,
egula ed by he ci cula ion o blood. Vi ali y is con olled by o al, ee and es e
choles e ol, albumin, ed blood co puscles (RBC) and haemoblobin, and he de ense
mechanism is con olled by immunoglobulins (IgG, IgA and IgM), whi e blood co -
puscles (WBC), monocy es, nu ophils, eosinophils and lymphocy es. Lymphocy es
a e subdi ided in o T and B lymphocy es. In addi ion, he ole o globulin-con aining
ac ions is also p ominen on his aspec . Unde mala ial condi ions, RBC, haemoglo-
bin and albumin dec ease whe eas WBC, neu ophils and globulins end o inc ease.
This is a e y b oad o e iew o his complex mechanism. In his con ex , a b ie
desc ip ion o he biology o mala ia is p esen ed.
1.1. Biology o Mala ia
Mala ia is caused by a pa asi e p o ozoan in ec ion. Fou di e en species o he ge-
nus Plasmodium a e known o in ec humans. In he opics, Plasmodium alcipa um
is mos p e alen . The li e cycle o he pa asi e is an in e ac ion be ween a emale
mosqui o o he genus Anopheles ( he ec o ) and he human hos . T ansmission o
disease occu s by a bi e o he in ec ious mosqui o. The pa asi e mig a es o he li e ,
emains in he la en s age o se e al days while eplica ing. Ul ima ely, he e occu s a
pene a ion o hos RBC wi h an asexual eplica ion wi hin he pa asi es which esul s
in he lysis o he cells. Mala ial symp oms a e occu ed by his asexual pa asi es in
he blood. When he e is a esh case o mosqui o bi ing, a sexual s age, called game-
ocy es de elops ( om he asexual pa asi es) which is esponsible o ansmission o
pa asi es om he hos . These ansmi ed pa asi es e ilize in mosqui o gu , eplica e
and a new cycle o ansmission s a s. These ypes o epidemiological su eys a e
gene ally based on blood smea s in which one can obse e bo h he asexual pa asi es
and game ocy es. Classi ica ions o blood smea s a e gene ally done in e ms o he
appea ance/absence o pa asi e o in e ms o i s densi y. Acco ding o abo e, he e
a e ac ually h ee classes o popula ion ela ed o he mala ial s a us- suscep ibles, he
p opo ion ha a e unin ec ed (Class 1); in ec eds, he p opo ion wi h in ec ion (Class
2); and immunes, he p opo ion wi h asymp o ic in ec ion which is no p ominen
366
(Class 4). The Feb ile Class i. e. Class 3 ep esen ed subjec s wi h uniden i ied e e ,
no mala ia (as con i med by slide es ).
1.2. Main Findings
Subsequen analysis o da a gi es some indica ion ha he le els o albumin, o al
choles e ol, o al p o ein, β- Globulin, γ-Globulin and IgG in he ci cula ing sys em
may be used o he p edic ion o mala ial endemici y o he ibal popula ion. The
ca ego ical a iables like blood g oups and sex a e less impo an o he p edic ion
o he mala ial incidence.
2. SAMPLING DESIGN AND COLLECTION OF DATA
A simple andom sample o 88 pe sons we e selec ed om he lis o olun ee s om
he ibal popula ion. Among hem, 45 we e male and 40 we e emale. The selec ed
indi iduals we e in i ed a he Clinics o Kokda and Khande be , o ganized by he
G am Vikas Kend a, a u al de elopmen cen e o Ta a Enginee ing and Locomo i e
Wo ks, Jamshedpu , Biha . The lis o olun ee s was p epa ed ea lie by he Cen e.
10 pe sons we e in i ed daily in he Clinics se ially om he cha . The a e age
daily a endance was six. This is because mos o he emales did no espond owing
o low li e acy le el, social- aboos o cus oms. The na u e o non esponse is qui e
andom in na u e and so his will no cause any bias in he expe imen . Howe e ,
he e iciency o he es ima o s will educe because o he educ ion o sample size.
Rele an his o y ega ding amily membe s, o al income o he amily and o he
socio- economic da a o he olun ee s we e collec ed by he Cen e and we e sen o
he Clinics o eco d. They we e mos ly non ege a ians esiding in hu s as usually
obse ed in ibal illages. Acco ding o hei amily income, hey belonged o he
«below po e y-le el»g oup.
2.1. Expe imen al p o ocol
Subjec s, as ins uc ed ea lie , came in pos -abso p i e s age (o e nigh as ing) in
he Clinics be ween 9 o 10 am. The a ending physician checked he weigh , pulse
and blood p essu e o each indi idual and d ew blood om hei b acial ein o
subsequen es ing. 10ml o blood was aken in an asep ic condi ion o he bioche-
mical, haema ological and immunological es s. Ou o his 10ml blood, 4ml was
kep in a s e ilized glass ial wi h he seques e ing agen . Blood smea was p epa ed
on wo glass slides, one hick ( o he de ec ion o Mala ial pa asi e) and he o he hin
367
( o di e en ial coun o he blood cells). The emaining po ion o blood was aken
in a s e ilized es ube and was allowed o clo o elease o se um.
The elec opho e ic sepa a ion o di e en p o ein ac ions was ca ied ou in he line
o Smi hies(1955) wi h 1% aga and 0.1M Ve onal Bu e (pH 8.6). The ac ions o
P o ein- Albumin and Globulins we e scanned by using a Densi ome e . The ela i e
pe cen age o di e en P o ein ac ions was measu ed by using a Planime e.
The Immunodi usions udy was pe o med acco ding o he s anda d me hod (Mancini
e al, 1965). The diame e o he p ecipi a ing ing was measu ed in mm by using he
‘Immunomeasu e’ scale. The s anda d cu e was plo ed on a double log g aph pape
using s anda d an igens supplied by M/s Immunodiagnos ics P . L d., Delhi. The
Immunoglobulin ac ions we e calcula ed om he s anda d cu e. The con en ional
me hods o he es ima ion o To al p o ein (Low y e al, 1951), To al, F ee and Es e
choles e ol(Woo on,1974), Haemoglobin, RBC,WBC,Blood g oups and Di e en ial
coun s i.e.es ima ion o Leucocy es, Monocy es, Eosinophiles, Basophils (Da ie and
Lewis,1984), T- and B- Lymphocy es (Blood, 1977) we e ollowed (Summa y ables
1A-1C). On he basis o he abo e pa hological es s he popula ion was pos s a i ied
in o ou Classes acco ding o hei mala ial s a us.
Class 1. No mal: Those who had no e e cu en ly and no pas his o y o mala ia
wi hin he las couple o yea s. To al numbe 20 (17 male and 3 emale)
Class 2. Mala ious: Those who u ned up wi h symp oms o mala ia and showed he
mala ial pa asi e posi i e in he ‘slide es ’. To al numbe 15 (11 male and 4 emale)
Class 3. Feb ile: Those who eme ged wi h e e bu no mala ial pa asi e was iden i ied
in he ‘slide es ’. To al numbe 25 (15 male and 4 emale).
Class 4. Do man : Those who had ecu ing mala ia du ing he las wo yea s bu
showed no cu en mala ial symp oms. To al numbe 28 (21 male and 7 emale).
3. STATISTICAL ANALYSIS
A: Analyses o ca dio ascula and blood pa ame e s
The means o he ollowing wen y one blood pa ame e s ( iz. To al P o ein (TP),
To al Chles e ol (Tch), F ee Chles e ol (Fc), Es e Choles e ol (Ec), Red Blood Co -
puscles (RBC), Whi e Blood Co puscles (WBC), Neu ophils (N), Lymphocy es (L),
Eosinophils (E), Monocy es (M), Haemoglobin (Hb), Immuno- globulin G (IgG), Im-
munoglobulin A (IgA), Immunoglobulin M (IgM), Albumin (Alb), α1-Globulin (α1),
α2-Globulin (α2), β-Globulin, γ-Globulin, T-cell (Tc), B-cell (Bc) and wo ca dio-
368
ascula pa ame e s, namely, Pulse (P) and Blood P essu e, Sys olic/Dias olic [Bp
(Sys/Dia)] o he ou classes o people (No mal, Mala ious, Feb in and Do man )
we e es ima ed h ough he sample means which a e gi en in he ables 1A, 1B and
1C. The es ima ed s anda d e o s (SR) o he es ima es a e also p esen ed in hese
ables. The ollowing able gi es an idea o he gene al heal h condi ion o he ibal
communi y unde conside a ion.
Table 1
Pa ame e s No mal Range mean s anda d s anda d P opo ion P opo ion P opo ion sample
Indian de ia ion e o (se) below abo e ou side ange
S anda d no mal no mal no mal min-max
ange ange ange
P(c/min) 65-85 94.898 15.834 1.688 0 70.11 70.11 68-124
BP/sys 100-140 110.932 13.118 1.398 17.04 0 17.04 78-150
BP/dia 70-90 76.33 10.783 1.149 20.45 4.54 24.94 54-100
WBC(m/cmm) 4000-10000 7185.8 931.853 99.336 0 0 0 5000-9500
α1(% Tp) 52-68 3.555 1.351 0.144 26.13 23.86 50 0.9-8.7
α2(%Tp) 6.1-10.1 3.838 1.697 0.181 89.7 0 89.7 1-9.9
β(% Tp) 8.5-14.5 6.619 2.495 0.266 84.1 0 84.1 2.4-14.5
γ(% Tp) 10-21 18.991 5.38 0.537 4.54 27.27 31.88 6-42.9
IgG(mg%) 700-1500 2453.69 598.515 63.802 0 85.22 85.22 1205-3477
IgA(mg%) 90-450 193.818 18.698 1.993 0 0 0 152-237
IgM(mg%) 40-250 128.352 28.642 3.053 0 0 0 69-192
Alb(% Tp) 52-68 67.436 7.046 0.751 2.27 51.13 53.46 45.7-85.1
N(%) 60-65 56.125 5.858 0.624 65.9 6.81 72.72 42-68
L(%) 20-40 33.318 4.797 0.511 0 7.95 7.95 24-48
E(%) 1-3 8.148 4.268 0.455 0 87.45 87.45 1-19
M(%) 2-8 2.614 1.309 0.14 13.63 0 13.63 1-6
Hb(gm%) 14-16 11.063 1.231 0.131 100 0 100 8-12.8
Tc(%) 70-75 63.5 6.447 0.687 80.68 0 80.68 42-75
Bc(%) 15-20 24.08 5.126 0.546 1.13 70.45 71.59 12-38
Tp(gm%) 6-8 7.142 0.387 0.041 0 0 0 6.5-8
Tch(mg%) 150-280 126.773 22.951 2.447 82.95 0 82.95 80-184
Fc(mg%) 50-70 42.045 13.597 1.449 78.4 2.27 80.68 20-94
Ec(mg%) 95-210 85.886 22.21 2.368 69.31 0 69.31 26-140
RBC(m/cmm) 4000-10000 3.794 0.474 0.051 98.86 0 98.86 2.31-4.78
F om he abo e able, we b ie ly commen on he a e age heal h condi ion as ollows:
BP: Due o he simplici y o li ing and die , he communi y unde s udy main ained
accep ably good BP le els.
369
RBC, Hb: Lowe alues indica e ha mos o he people a e anaemic.
Tp, Tch, Fc, Ec: Lowe alues han he no mal ange is indica ion o low a die s
coupled wi h no mal p o ein le els.
E: High concen a ion o eosinophils is gene ally co ela ed wi h pa asi ic in ec ion
in he people.
WBC, N, L, M: The le els o hese pa ame e s a e accep able in e ms o acili a ing
immnuno-de ence mechanism.
Summa y Table: 1A
Class Sample S a is ic P BP/sys BP/dia TP Tch Fc Ec RBC WBC
size (coun /min) (mm Hg) (mm Hg) (gm%) (mg%) (mg%) (mg%) (m/cumm) (no/coun )
mean 91.6 112.6 77.7 7.08 136.2 39.2 102.5 4.062 7707.5
1 20 sd 16.28005 8.9241 8.97273 0.32031 21.7154 11.26765 14.42047 0.28971 816.13035
se 3.64033 1.9955 2.00636 0.07162 4.85572 2.51952 3.22451 0.06478 182.19229
mean 94.06667 108.67 7606 6.94666 96 38.63333 57.46667 3.72133 6736.66667
2 15 sd 15.48533 13.656 12.04326 0.23907 10.0133 14.50455 13.9421 0.48780 772.97405
se 3.99829 3.526 3.10955 0.06172 2.58543 3.74506 3.59983 0.12595 199.58104
mean 100.4 106.36 72.92 7.156 136.16 45.72 90.12 3.6264 7084
3 25 sd 15.09967 14.982 10.9724 0.43458 20.9908 13.92413 19.17982 0.43472 953.90984
se 3.01993 2.9965 2.19448 0.08691 4.19816 2.74482 3.83596 0.08694 190.78197
mean 92.78571 115.04 78.25 7.27857 128.143 42.67857 85.45429 3.79071 7144.64286
4 28 sd 15.065 11.975 10.35659 0.39402 14.8413 13.40589 17.97713 0.52002 898.54438
se 2.84701 2.263 1.95721 0.07446 2.80475 2.53347 3.39735 0.09827 169.80892
Summa y Table: 1B
Class Sample S a is ic N L E M Hb Tc Bc
size (%) (%) (%) (%) (gm%) (%) (%)
mean 55.45 32.85 9.65 2.05 11.82 65 23.1
1 20 sd 4.225 3.454 3.825 0.805 0.621 4.278 4.3
se 0.945 0.772 0.855 0.18 0.139 0.957 0.962
mean 53.667 36.4 5.667 4.267 10.647 63.733 23.6
2 15 sd 5.907 4.514 3.32 1.289 1.447 5.234 5.414
se 1.525 1.165 0.857 0.333 0.374 1.351 1.398
mean 588 31.56 7.64 2.64 10.704 62.16 25.32
3 25 sd 6.203 5.375 4.906 1.353 1.144 7.22 5.732
se 1.241 1.075 0.981 0.271 0.229 1.444 1.146
mean 55.536 33.571 8.857 2.107 11.064 63.5 23.929
4 28 sd 5.635 4.346 3.71 0.673 1.257 7.287 4.705
se 1.065 0.821 0.701 0.127 0.238 1.377 0.889
370
Summa y Table: 1C
Class Sample S a is ic IgG IgA IgM Alb α1α2β γ
size (mg%) (mg%) (mg%) (%) (%) (%) (%) (%) (%)
mean 1519.3 199.65 114.35 73.985 3.095 3.135 4.83 14.885
1 20 sd 199.158 19.132 28.079 5.513 1.28 1.042 1.36 4.62
se 44.533 4.278 6.279 1.233 0.286 0.233 0.304 1.003
mean 2870.333 182.6 129.067 58.74 3.68 4.353 8.267 24.867
2 15 sd 277.906 19.231 24.845 6.706 1.574 2.513 3.374 6.182
se 71.755 4.965 6.415 1.732 0.407 0.649 0.871 1.596
mean 2777.96 190 135.84 67.844 3.792 3.74 5.084 19.48
3 25 sd 410.31 15.773 33.308 3.86 1.406 1.484 1.606 3.417
se 82.062 3.155 6.662 0.772 0.281 0.297 0.321 0.683
mean 2608.393 199.07 131.286 67.054 3.604 4.136 6.971 18.339
4 28 sd 267.147 16.873 22.247 5.046 1.125 1.527 2.125 3.693
se 50.486 3.189 4.204 0.954 0.213 0.289 0.402 0.698
B: Analysis o Va iance
In his sec ion, we will s udy whe he o no he means o 21 blood pa ame e s, BP
(Sys ol/Dias ol) and pulse a es a e di e en o 4 classes o people desc ibed abo e.
Fo his s udy, we conside he ollowing wo way analysis o a a iance model using
class and sex as wo classi ying ac o s o each o he 21 blood pa ame e s, pulse
a e and BP (Sys ol/Dias ol):
yi
;
j
;
k
(
) =
m
+
a
(
i
) +
b
(
j
) +
c
(
i
;
j
) +
ei
;
j
;
k
(1)
whe e yi
;
j
;
k
(
) =
esponse ob ained om he k h indi iduals o he j h
(
j
=
0
;
1
)
sex
o he i h
(
i
=
1
;
2
;
3
;
4
)
class, co esponding o he pa ame e , .
m
=
gene al e ec
a
(
i
) =
e ec due o i h class
(
i
=
1
; : : : ;
4
)
a
(
j
) =
e ec due o j h sex
(
j
=
0
;
1
)
a
(
i
;
j
) =
in e ac ion e ec be ween i h class and j h sex
Assump ions o he Analysis o a iance model:
(a) ∑
ia
(
i
) =
∑
jb
(
j
) =
∑
ic
(
i
;
j
) =
∑
jc
(
i
;
j
) =
o
371
(b) e
(
i
;
j
;
k
) =
independen ly and iden ically dis ibu ed as no mal a ia e wi h mean
ze o and a iance σ2.
The assump ions o he model imply ha yi
;
j
;
k
(
)
’s a e independen ly no mally dis-
ibu ed wi h mean m
+
a
(
i
) +
b
(
j
) +
c
(
i
;
j
)
and a iance σ2. Since he numbe o
obse a ions o he 4 classes (20, 15, 28) a e di e en , unbalanced analysis o a ince
echniques a e used. This is clea ly explained wi h an example by Kshi saga (1983).
Following he analysis o a iance ables, he e ec s o β,γ, IgG, Alb, Tp, Tch and
Ech we e ound o be signi ican . This implies ha he mean o each o he pa ame e s
β,γ, IgG, Alb, Tp,Tch and Ech is di e en o 4 classes. The compu a ions o hese
pa ame e s a e shown in he ables (2A -2G).
Table 2A: ANOVA
(
β
β
β
)
Sou ce ss d ms F- alue P- alue
Class 123.106 3 41.035 8.141 0
Sex 0.303 1 0.303 0.06 0.807
In e ac ion 1.754 3 0.585 0.116 0.951
E o 403.26 80 5.041
Table 2B: ANOVA
(
γ
γ
γ
)
Sou ce ss d ms F- alue P- alue
Class 627.839 3 209.28 10.509 0
Sex 39.157 1 39.157 1.966 0.165
In e ac ion 35.099 3 11.7 0.588 0.625
E o 1593.121 80 19.914
Table 2C: ANOVA (IgG)
Sou ce ss d ms F alue P alue
Class 14318260 3 4772753.3 47.721 0
Sex 68669.954 1 68669.954 0.687 0.41
In e ac ion 65112.199 3 3360328.2 33.599 0.844
E o 8001077.2 80 100013.47
372
Table 2D: ANOVA (Alb)
Sou ce ss d ms F alue P alue
Class 1236.765 3 412.255 14.108 0
Sex 0.011 1 0.011 0 0.984
In e ac ion 31.364 3 10.455 0.358 0.784
E o 2337 80 29.222
Table 2E: ANOVA (TP)
Sou ce ss d ms F- alue P- alue
Class 2.212 3 0.737 3.892 0.012
Sex 0.033 1 0.033 0.172 0.679
In e ac ion 0.465 3 0.155 0.817 0.488
E o 15.159 80 0.189
Table 2F: ANOVA (TCH)
Sou ce SS d ms F- alue P- alue
Class 13386.909 3 4462.303 13.466 0
Sex 1.986 1 1.986 0.006 0.938
In e ac ion 1477.278 3 492.426 1.486 0.225
E o 26509.82 80 331.373
Table 2G: ANOVA (EC)
Sou ce ss d ms F- alue P- alue
Class 14398.88 3 4799.627 15.454 0
Sex 272.46 1 272.46 0.877 0.352
In e ac ion 249.905 3 83.302 0.268 0.848
E o 24846.723 80 310.584
373
