Table 1.

Summary statistics and proportions of variance explained by genetics and other sources for the number of clinical attacks per person and the severity of symptoms in a population in Sri Lanka as estimated by different models

Trait	No. of records	Mean*	Phenotypic variance,* σP2	Percentage of phenotypic variance explained†
				Random effects (SE)‡				Fixed effects§
				Genetic h2	Other personal m2	Total personal h2 + m2	House c2	1A	Model 2A	3A
Number of infections (group A traits)
With zeroes¶
Both species	1771	0.71	1.16	14–18 (7)			12–21 (4)	0	10	18
P. falciparum	1769	0.23	0.24	8–21 (7)			4–13 (3)	0	9	16
P. vivax	1771	0.48	0.85	10–17 (7)			11–17 (4)	0	9	16
Without zeroes¶
Both species	739	1.69	1.11	15–21 (12)			3–7 (6)	0	5	14
P. falciparum	737	0.55	0.41	10–25 (13)			5–10 (6)	0	7	9
P. vivax	739	1.14	1.28	2–5 (11)			8–11 (6)	0	2	9
							Model	1B	2B	3B	4B
Sickness scores (group B traits)
Total score	1246	11.0	17.3	8–10 (7)	1–14 (6)	11–22	3–4 (4)	6	16	10	20
Aches‖	1076	3.90	7.09	4–6 (9)	9–24 (8)	13–29	0–2 (5)	9	28	10	29
Gastrointestinal‖	1076	1.82	2.07	10–13 (9)	2–4 (8)	14–17	3–4 (4)	1	4	6	8
Fever‖	1076	3.09	2.78	12–15 (9)	0–5 (9)	14–17	5–7 (4)	2	3	6	8
Headache	1144	2.11	0.87	3–5 (7)	17–22 (8)	20–27	0–7 (4)	7	9	7	10
Hypo. pain	1093	0.35	0.28	6–13 (9)	0–1 (9)	6–13	1–5 (5)	2	3	6	8
Other measures (group B traits)
Temperature	1201	38.03	1.14	0–0 (7)	0–9 (6)	0–9	3–5 (9)	1	8	23	26
Parasitemia (%)
P. falciparum	406	0.063	0.102	16–24 (22)	1–12 (21)	16–35	0–1 (11)	0	11	2	11
P. vivax	839	0.094	0.030	0–6 (15)	6–19 (15)	12–19	4–10 (7)	2	12	21	21
Gametocytemic
P. falciparum	406	0.042	0.040	0–0 (24)	0–1 (21)	0–1	0–0 (5)	1	0	0	0
P. vivax	839	0.277	0.200	0–1 (11)	2–5 (11)	4–6	0–0 (3)	5	6	14	14
No. days symp.	1246	2.81	2.76	3–5 (8)	5–7 (7)	8–15	0–3 (5)	0	4	2	5

^*On the untransformed scale, unadjusted for fixed effects. 

^† Range of estimates from models with different fixed effects. 

^‡ Averaged over all models, where estimable. 

^§ Fixed effects in each model are as follows. Group A traits: model 1A, none; model 2A, village; model 3A, village and other predisposing (sex, age, occupation); group B traits: model 1B, nuisance effect (interviewer); model 2B, nuisance and predisposing effects; model 3B, nuisance and immediate effects; model 4B, nuisance, predisposing and immediate effects. See text. 

^¶ “With zeroes” and “Without zeroes” includes and excludes, respectively, records from people who had no clinical attacks during the study period. 

^‖ Trait analyzed was the first principal component of a group of related traits.