Factors Associated with Household Rodent Infestation in a Suburban Area of Nonthaburi Province, Thailand

Abstract

Although rodents can spread over 35 diseases and cause enormous economic loss by damaging property, crops and food supplies, information needed to manage the rodent problem in Thailand is limited to some urban and rural areas only.  In order to develop a comprehensive strategic plan on rodent control, the risk factors of household rodent infestation in different social contexts, especially in areas with a combination of traditional and modern life, need to be explored. Therefore, this research aimed to determine factors associated with rodent infestation in a suburban area by selecting Klong Prarum Village, Nong Phrao Ngai Subdistrict, Sai Noi District, Nonthaburi Province, Thailand, as a case study.

Along with a rodent sign survey, data on house characteristics (dwelling type, house structure, space under the house), socio-economic status of homemakers (dwelling ownership, educational attainment, occupation, income) and environmental factors supporting household rodent infestation (food sources, water sources, harborages and entries) were collected from 152 households comprising of 76 traditional houses, 63 modern houses and 13 row houses. The associations between house characteristics, socio-economic status and rodent infestation were explored using univariate binary logistic regression. As a further step, environmental risk factors for rodent infestation of each dwelling type were quantified.

            Fifty-six-point six percent of the inspected houses were vulnerable to rodent infestation by which signs were present in 78.9% of traditional houses, 38.5% of row houses and 33.3% of modern houses. According to the sizes and characteristics of rodent droppings, roof rats (Rattus rattus) and mice (Mus musculus) were equally tracked in traditional houses and the vast majority of rodents in modern and row houses were mice. When variables of socio-economic status and house characteristics were analyzed, only education level and type of dwellings were significantly associated with rodent infestation (p <0.001 and p = 0.001, respectively). Regarding the odds ratio, houses of homemakers with lower educational attainment were associated with increased rodent infestation (OR = 4.16, 95% CI = 1.81-9.57). In addition, the probabilities of rodent infestation in traditional and row houses were 7.50 (95% CI = 3.51-16.05) and 1.25 (95% CI = 0.36-4.25) times higher than that in modern houses, respectively. When environmental risk factors of each dwelling type were quantified, 5 factors, i.e., inappropriate storage of grains and animal food (OR =5.33, 95% CI =1.22-23.29), disorganized outdoor material storage (OR=4.20, 95% CI = 1.21-14.55), overhanging tree branches/materials (OR=5.31, 95% CI =1.60-17.67), leaving doors/windows open (OR=10.89, 95% CI = 2.64-44.86) and deteriorated fascia board at the roof edge  (OR =10.89, 95% CI =2.64-44.86) showed significant associations with rodent infestation in traditional houses. However, only 3 factors, i.e., inappropriate food storage (OR=5.64, 95% CI =1.81-17.60), improperly placed furniture/equipment (OR=5.64, 95% CI =1.81-17.60) and disorganized outdoor material storage (OR=4.55, 95% CI = 1.26-16.44) were significantly associated with rat infestation in modern houses.

            These data indicated that dwelling type and lifestyle might determine the extent of household rodent infestation and the type of rodents. Traditional house structures were less protective. For example, fascia boards at the roof edges always deteriorated due to aging. Also, most owners, whose occupations were agriculturalists, usually left unscreened doors or windows open. Together with overhanging tree branches around the houses, these conditions provided significant access for roof rats and mice. Moreover, people used space under or close to the housing area to store grains, animal food, agricultural tools and abandoned appliances; therefore, providing favorite food sources and harborages for rodents.  For modern houses, well protected structures were able to prevent rats from entering the house but some defective small holes on the building exterior could not prevent the entry of mice. Consequently, inappropriate food storage and improperly placed furniture/equipment inside the house provided significant food sources and harborages, respectively.  To reduce rodent populations in each dwelling type, all food sources, harborages and entries, especially the aforementioned factors should be organized or fixed. However, community members should cooperate to control pests, otherwise rodents will migrate to nearby residences with sanitation deficiencies.