Risk factors of malaria infection in people returned from a travel to Africa in Shanglin, Guangxi

doi:10.12140/j.issn.1000-7423.2019.05.006

Abstract

Abstract:

Objective To identify the risk factors related to malaria infection in those who traveled to Africa and returned to Shanglin County of Guangxi. Methods An epidemiological investigation and Plasmodium detection were done using a case-control study method in 2018. The cases with Plasmodium positive examined by microscopy or PCR test were grouped as case group, while those with negative results were grouped as a control group. The malaria infection risk factors were investigated by a questionnaire answered by those returned from a travel to Africa, with and without malaria infection. The questionnaire included general information, past medical history and anti-malaria treatment, working and living conditions when abroad, knowledge of malaria prevention and control and behavioral awareness related to malaria infection and so on. The collected information was analyzed to compare the difference of each factor between the case group and the control group. The potential risk factors related to malaria infection were analyzed using an unconditional multivariate logistic regression analysis method by setting the case group as the result variable and other factors as the explanation variable. Results Total 465 people returned from a travel to Africa were enrolled in the investigation related to the malaria infection in Africa, among them 149 were identified as Plasmodium infection positive and 316 as negative. Univariate analysis showed that there were significant differences for the five variables between the case group and the control group (P ≤ 0.05), including age (< 30: 17.5% and 7.6%, 30-39: 40.3% and 40.8%, 40-39: 24.2% and 32.6%, ≥ 50: 18.1% and 19.0%）, living ecological environment (forest: 41.6% and 43.4%, jungle: 41.6% and 26.3%, meadow: 5.4% and 3.5%, uncultivated: 10.7% and 22.8%, mixed: 0.7% and 4.1%), the cultivated crop type (rice: 95.3% and 89.9%, other: 4.7% and 10.1%), outdoor activities in the evening (yes: 56.4% and 62.0%, no: 43.6% and 38.0%), and outdoor activity spent time (no: 43.6% and 38.0%, 1-30 min: 8.1% and 17.4%, 31 min-1 h: 1.3% and 2.9%, 1-2 h: 0.7% and 1.6%, ≥ 2 h: 46.3% and 40.8%), respectively. Multivariate logistic regression analysis showed that the living environment in Africa for case group and control group was in city： 4.0%, 2.2%; in countryside: 7.4%, 3.5%; in the wild: 87.3%, 91.8%; and mixed： 1.3%, 2.5%, respectively, with OR = 1.8(1.0-2.8). The living house for case group contained less percentage of window and door screen (7.4%) than control group (12.0%) with OR = 0.2 (0.1-0.8). Conclusion The results conclude that people who lived in houses without door and window screens, went outdoors in the evening, and spent longer time outdoors had higher chance to get malaria and these activities are the important risk factors for malaria infection in Africa. Interestingly, people living in the city or integrated areas had the higher risk to get infected than those living in the field.

Key words: Malaria, Risk factors, Case control study, Persons returned from Africa

CLC Number:

R531.3

Kang-ming LIN, Duo-quan WANG, Shi-zhu LI, Ying-jun QIAN, Jun-yun WANG, Jun-hu CHEN, Bin XU, Jian TAN, Jian-feng CHEN, An-xiang MA, Fei LUO, Wei-dong LI, Tao ZHANG, Jun LI, Yi-chao YANG, Xiao-nong ZHOU. Risk factors of malaria infection in people returned from a travel to Africa in Shanglin, Guangxi[J]. CHINESE JOURNAL OF PARASITOLOGY AND PARASITIC DISEASES, 2019, 37(5): 539-544.

Figures/Tables 1

Table 1

Univariate and multivariate logistic analyses of the risks related to malaria infection between case group and control group in those traveled to Africa and returned to Shanglin County, Guangxi

特征Feature	病例组（n = 149） Case group（n = 149）				对照组（n = 316） Control group(n = 316)				单因素分析 Univariate analysis		多因素分析 Multivariate analysis
特征Feature	例数 No. cases		构成比/% Proportion/%		例数 No. cases		构成比/% Proportion/%		P		OR（95% CI）			P
性别Gender
男Male	143		96.0		311		98.4		&#x0003E; 0.05		1			&#x0003E; 0.05
女Female	6		4.0		5		1.6				0.5（0.1~3.5）
年龄Age
&#x0003C; 30	26		17.5		24		7.6		&#x0003C; 0.05		0.8（0.6~1.1）			&#x0003E; 0.05
30~39	60		40.3		129		40.8
40~49	36		24.2		103		32.4
&#x02265; 50	27		18.1		60		19.0
文化水平Educational level
小学Primary school	11		7.4		24		7.6		&#x0003E; 0.05		1.4（0.7~2.5）			&#x0003E; 0.05
初中Junior high school	123		82.6		267		84.5
高中及以上 Senior high school and above	15		10.1		25		7.9
外出国家 Traveled countries
中非Central Africa	56		37.6		146		46.2		&#x0003E; 0.05		1			&#x0003E; 0.05
西非West Africa	89		59.7		162		51.3				1.3（0.8~2.2）
其他区域^a Others^a	4		2.7		8		2.6				2.1（0.5~8.8）
职业Job abroad
淘金挖矿Gold Mining	147		98.7		310		98.1		&#x0003E; 0.05		1			&#x0003E; 0.05
其他Others	2		1.3		6		1.9				0.5（0.4~5.6）
近一年患病次数No. of malaria infection during the past year
0	16		10.7		49		15.5		&#x0003E; 0.05		1.4（1.0~2.0）			&#x0003E; 0.05
1~2	42		28.2		102		32.3
&#x02265; 3	91		61.1		165		52.2
境外预防服药 Take preventive medicine abroad
有Yes	7		4.7		16		5.1		&#x0003E; 0.05		0.6（0.2~1.8）			&#x0003E; 0.05
无No	142		95.3		300		94.9
国外居住地The living environment abroad
城市City	6		4.0		7		2.2		&#x0003E; 0.05		1.8（1.1~2.8）			&#x0003C; 0.05
农村Countryside	11		7.4		11		3.5
野外Wild	130		87.3		290		91.8
综合^b Mixed^b	2		1.3		8		2.5
所住房屋条件Living house condition
砖瓦房Brick house	9		6.0		15		4.8		&#x0003E; 0.05		2.0（0.7~5.7）			&#x0003E; 0.05
工棚或集装箱房Shed or container room	138		92.6		292		92.4
草木房Grass wood house	2		1.3		7		2.2
综合^c Mixed^c	0		0.0		2		0.6
房屋有无纱门纱窗Door and window screen of the house
有Yes	11		7.4		38		12.0		&#x0003E; 0.05		0.2（0.1~0.8）			&#x0003C; 0.05
无No	138		92.6		278		88.0
居住点周边主要生态环境 Living ecological environment
森林Forest	62		41.6		137		43.4		&#x0003C; 0.05		1			&#x0003E; 0.05
丛林Jungle	62		41.6		83		26.3				6.5（0.4~101.8）
草地Meadow	8		5.4		11		3.5				9.8（0.7~133.1）
荒地Uncultivated	16		10.7		72		22.8				3.5（0.3~47.1）
综合生境^d Mixed^d	1		0.7		13		4.1				5.1（0.4~70.3）
当地农作物类型The cultivated crop type
水稻Rice	142		95.3		284		89.9		= 0.05		0.8（0.3~2.1）			&#x0003E; 0.05
其他Others	7		4.7		32		10.1
使用防蚊措施 Use of mosquito control measures
蚊帐Mosquito net	12		8.1		40		12.7		&#x0003E; 0.05		2.7（0.4~20.8）			&#x0003E; 0.05
趋避剂Mosquito repellent	2		1.3		5		1.6				0
未采取任何措施No measures	0		0.0		2		0.6				1.5（0.6~3.6）
综合^e Mixed^e	135		90.6		269		85.1				1
傍晚后是否经常在户外活动 Outdoor activities in the evening
是Yes		84		56.4		196		62.0		&#x0003E; 0.05		1	&#x0003E; 0.05
否Yes		65		43.6		120		38.0				1.3(0.4~4.0)
户外活动时间Outdoor activity time
无外出No		65		43.6		118		37.3		= 0.05		1.1（0.8~1.5）	&#x0003E;0.05
1~30 min		12		8.1		55		17.4
31 min~1 h		2		1.3		9		2.9
1~2 h		1		0.7		5		1.6
&#x02265; 2 h		69		46.3		129		40.8
出国前疟疾知识宣传培训Malaria prevention training before going abroad
有Yes		49		32.9		127		40.2		&#x0003E; 0.05		1	&#x0003E; 0.05
无No		100		67.1		189		59.8				0.9（0.5~1.7）
在国外疟疾知识宣传培训 Malaria awareness training while abroad
有Yes		2		1.3		2		0.6		&#x0003E; 0.05		1	&#x0003E; 0.05
无No		147		98.7		314		99.4				0.3（0.0~3.3）

Table 1

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