Prevalence of asymptomatic Plasmodium infections with sub-microscopic parasite densities in the northwestern border of Thailand: a potential threat to malaria elimination

Table 5 Demographic characteristics of the study population associated with asymptomatic sub-microscopic Plasmodium infections

Characteristics	Total samples	Prevalence of sub-microscopic infections^a, n (%)	Odds Ratio (95% CI)	P value^b
Gender
Male	1615	32 (1.98%)	1.32 (0.85–2.05)	0.223
Female	2035	53 (2.6%)	1.32 (0.85–2.05)	0.223
Age (years)
≤ 5	636	9 (1.42%)	Ref. group	–
6–15	1249	25 (2%)	1.43 (0.66–3.07)	0.366
16–30	640	18 (2.81%)	2.02 (0.9–4.54)	0.087
31–45	579	19 (3.28%)	2.36 (1.06–5.27)	0.035*
46–60	338	9 (2.66%)	1.91 (0.75–4.85)	0.175
> 60	208	5 (2.4%)	1.71 (0.57–5.17)	0.339
Body temperature^c (°C)
≥ 37.5	186	4 (2.15%)	0.96 (0.35–2.66)	0.94
< 37.5	3411	76 (2.23%)	0.96 (0.35–2.66)	0.94
Citizenship
Thai citizenship	1508	34 (2.25%)	1.06 (0.68–1.64)	0.795
Foreigner	2142	51 (2.38%)	1.06 (0.68–1.64)	0.795
Study site
Nong Bua	1579	49 (3.1%)	4.45 (1.59–12.38)	0.004*
Tala Oka	883	12 (1.36%)	1.91 (0.61–5.96)	0.264
Mae Salid Noi	560	4 (0.71%)	Ref. group	–
Suan Oi	359	20 (5.57%)	8.26 (2.79–24.37)	0*
Ko Ma Nae	165	0 (0%)	0	1
Pha Man	72	0 (0%)	0	1
Orphanage	32	0 (0%)	0	1
Occupation
Student	1440	32 (2.22%)	1.58 (0.75–3.33)	0.23
Hireling/labour	781	18 (2.32%)	1.64 (0.73–3.68)	0.229
Child	633	9 (1.42%)	Ref. group	–
Plantation	493	19 (3.85%)	2.78 (1.24–6.19)	0.013*
Housekeeper	74	0 (0%)	0	1
Merchant	66	4 (6.06%)	4.47 (1.34–14.92)	0.015*
Other (e.g., cripple, retired, monk, government officer)	163	3 (1.84%)	1.29 (0.35–4.85)	0.698

*Statistically significant difference
^aSub-microscopic infection was defined when the sample was LAMP-positive but microscopy negative
^bP values were obtained by binary logistic regression and is significant at < 0.05
^c53 samples were excluded since the body temperature data was not available

ISSN: 1475-2875