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. Author manuscript; available in PMC: 2013 Nov 21.
Published in final edited form as: Nat Med. 1998 Mar;4(3):358–360. doi: 10.1038/nm0398-358

Table 1.

Agglutination of parasite infected red cells by sera from clinical isolates and controls

n Agglutination
frequency (%)		 Odds ratio
(confidence interval)		 P valuea Parasite
rate (%)B
Controls in zones
 producing cases		 861 20.2 1.07 (0.79-1.45)c 0.70 35.0
Controls in zones
 without cases		 434 19.1 33.2
Homologous parasites
Control d 1295 19.8 34.4
Indexe 65 4.6 0.20 (0.04-0.60)f 0.004 32.3
Acuteg 65 35.4 2.21 (1.26-3.85)h 0.004
Parasite 1759i
Controls 156 34.0 39.7
Index 52 30.8 0.86 (0.42-1.78)f 0.80 28.9
Acute 52 34.6 1.03 (0.50-2.09)h 0.93
a

P value from a Yates corrected chi-square test. P values agreed well with those calculated using logistic regression (not shown).

B

Percentage of samples in which one or more parasites were observed in 200 fields of a thick blood film.

c

Comparison, using the pooled data from 65 assays, between agglutination frequency in controls from zones producing malaria cases and controls from zones that did not.

d

For each index case, 20 control sera tested, except for five assays in which only 19 controls were used; a total of 1295 controls were tested against 65 isolates.

e

Each parasite tested against corresponding serum collected in May 1995.

f

Comparison between agglutination frequency in index sera and control sera.

g

Each parasite was tested against the corresponding acute plasma sampled at the time of presentation with malaria.

h

Comparison between agglutination frequency in acute plasma and control sera.

i

Sera from 52 index cases and 156 controls tested against heterologous parasite 1759.