Knowledge, attitudes, and practices towards mosquito control and used vehicle tire dumping by median household income, in metropolitan New Orleans, Louisiana

Ethics

The project received ethical exemption from the University of Miami Institutional Review Board (IRB ID: 20161212).

Study design

A descriptive cross-sectional design study of New Orleans, Louisiana households residing in affluent neighborhoods (n = 10) and low-income neighborhoods (n = 71). The city of New Orleans has 73 distinct neighborhoods grouped into 13 planning districts, and approximately 61 Zip Codes (New Orleans City Planning Commission, 2016), and illegal used vehicle tire discarding continue to be a problem (WDSU, 2021). Data were collected from November 2018 through October 2019. Households were recruited via internet, survey, and during neighborhood engagement meetings.

Study settings

Orleans Parish and the City of New Orleans are coterminous (Moise, Riegel & Muturi, 2018), and is located at 105 miles upriver from the Gulf of Mexico, and in the Mississippi River Delta, south of Lake Pontchartrain, on the banks of the Mississippi River. It is located at 90°4′14″W and latitude 29°57′53″N, with an elevation range of −6.5 to 20 ft. Mosquito season usually begins in the spring (March) and slows down in the fall (November to December) depending on temperature.

Study sample

First, to select study households, home addresses of New Orleans households were purchased from Infogroup (now Data Axle, Papillion, NE, USA). Second, a two-stage cluster random sampling procedure was used to calculate a sampling interval (SI) by dividing the total population in the study area (33,870) into 24 clusters selected from 61 New Orleans Zip Codes using a probability proportional to population size. Cumulative Zip Code population sizes were calculated by size of each Zip Code’s population, with a range developed for each Zip Code. To determine the clusters, first, we randomly selected a number between 1 and a calculated sampling interval of 3,354.3. The Zip Code with the selected number (e.g., 12) was used as the first sampling cluster. The second cluster was determined by adding the sampling interval to this number—a process that continued until 24 clusters were identified. In stage 2 and to avoid bias, the office secretary assigned home addresses on small pieces of papers from which the sample of households per Zip Code were selected per cluster/Zip Code with envelops assigned with the unique identification numbers. Third, Cochran’s formula (Smart Methodology, 2012) was used to estimate a sample size with a power of 80% with a 5% margin of error and 95% confidence interval. Because the prevalence of KAP in the New Orleans communities is new, a sample size was estimated by assuming that 50% of the population has baseline knowledge about illegal tire discarding and the role that tires serve as an important habitat for mosquito larvae as was calculated in a related study (Selvarajoo et al., 2020). A minimum of 384 completed surveys were required for this study: with an additional 10% to capture non-response for a final sample of 422 households.

Study participants

All households aged at least 18 years or older (mostly heads of households consenting to take the survey) and providing informed consent completed the survey. In cases where the head of household was absent, a person aged 18 years or older completed the survey. We initially pilot tested the questionnaire with 10 participants at neighborhood engagement meetings. The research was conducted in line with the guidelines provided towards human subject research compliance with written informed consent forms.

Survey instrument

To collect data, we utilized a self-administered, 62 itemed questionnaire comprising of five sections developed using a combination of questions from various KAP surveys, and the first author’s surveys (Moise, Sheskin & Fuller, submitted). In addition to the three screening questions (residency status, age, length of residence), the questionnaire included 12 questions about tire sightings, tires in own yard, willingness to report if an illegal dumping is observed and to participant in a cleanup effort (very unlikely, unlikely, somewhat likely, likely). Ten questions addressed preferred communication method for receiving information about public health and tire dumping, seven questions addressed perceived effective education strategies and 12 questions addressed knowledge towards mosquitoes and disease risk (e.g., diseases transmitted by mosquitoes, mode of transmission, time of day when mosquitoes are more likely to bite, city tire pick-up every second of the week (yes, no)), frequency of being bite around the home (very frequently, frequently, occasionally, and seldom or never), and mosquito-breeding sites.

To measure attitudes related to mosquito and illegal tire disposal (seven questions) comprised the perceptions towards control measures (reducing mosquito populations could avoid mosquito borne disease, mosquito borne diseases a serious health problem, spraying is the best method to reduce mosquito populations, the City of New Orleans is responsible for reducing the number of mosquito larvae, it is my individual responsibility to prevent the spread of mosquito, I am willing to report an illegal dumping if i see one and I am willing to participate in tire clean-up efforts). Strongly agree to agree responses were combined and assigned a score of 1 where responses yielding strongly disagree or disagree were assigned a score of 0.

Preventative behavior practices were measured using nine items covering two categories: (1) source reduction measures (five questions e.g., applying bleach and/or detergents to water basins and water containers, eliminate stagnant water, fumigate, apply larvicide, use of fishes on water containers, and cover or empty water containers), and (2) preventing mosquito bites (four questions e.g., use of insecticide, repellents, screens in window and doors, fans, and bed nets). These questions also yielded yes or no responses. The questionnaire was the tested for its reliability and validity with participants at neighborhood engagement meetings, with internal consistency evaluated using Cronbach’s alpha (α = 0.78) (Smart Methodology, 2012), and piloted with 10 participants.

Socio-demographic and housing variables of interest included age, sex, race/ethnicity, highest level of education, home five-digit Zip Code, marital status, current employment status, household income, type of current housing (owner occupied, rental, other), knowledge (n = 3 questions), attitudes (n = 4 questions), and practices (n = 2 questions). Respondent sex was classified and coded as male, 0, female, 1 and other, 3. Because only respondents aged 18 years or older completed the survey, age which was collected as a continuous variable was categorized into four categories 18–24: 0, 25–34: 1, 35–44: 2, 45+, 3 and missing, 999. Because the survey was purposefully designed to distinguish those who achieved higher education from those who did not, education was dichotomized into four categories less than a high school diploma: 0, some college: 1, bachelor’s degree: 2, and graduate degree: 3. Marital status was classified and coded as single (never married): 0, married or in a domestic partnership: 1, widowed, divorced, or separated: 2. Employment status was classified and coded as employed full-time: 0, employed, part-time: 1, unemployed: 2, retired or disabled: 3. Homeownership was categorized and coded as owner occupied: 0, rental: 1, other: 2, and property type was classified and coded as single-family home: 0, duplex: 1, apartment: 2, condominium: 3 and other property types: 4.

We delineated household income based on the reported participant household annual income and residence Zip code. In New Orleans, the lowest zip code household income value is $7,448, and the highest value is $73,042. In the sample, half of the values have household incomes between $19,000 and $30,000. The middle (median) household income value was $45,615. Based on this, KAP study households (respondents) were classified into two distinct median household income ranges; low (respondents with household incomes above the New Orleans middle (median)) household income of $45,615, and high-income (respondents whose median household income was above the median).

Statistical analysis

Descriptive statistics of socio-demographic and housing factors of respondents were calculated and presented as frequency (percentage (%) for categorical variables) and as mean (M) ± standard deviation (SD, for continuous variables). Univariate analysis was realized by creating contingency tables and then performing Chi-square test. To compare the KAP levels (good, moderate, or poor) and the variables of interest by median household income, the effect size was estimated using Cramer’s V (for R*C tables) or Phi (for 2 × 2 tables).

Regarding knowledge, attitudes, and practices (KAP) outcome variables (KAP scores), first we assigned each respondent’s correct answer to KAP domain questions a score of ‘1’ and a ‘0’ to each wrong response. Second, we summed each respondent’s correct KAP responses and calculated their KAP scores. A cut-off point of 80.0–100.0%, 60.0–79.0%, and ≤59.0% was used to categorize each respondent’s overall KAP score. Because the overall KAP scores were highly skewed and discontinuous, we transformed the KAP scores into ordinal variables (poor, moderate, good), with a good score ranging between 8 and 10 points, a moderate score ranged from 6 and 7.9 points and a poor score was any respondents scoring less than <6 points as used in previous related KAP studies (Flatie & Munshea, 2021; Moise et al., 2018). For instance, with a total of 12 questions in the knowledge domain, a respondent scoring 10 or more scores was classified as having good level of knowledge, and this was true for attitude and preventative measures (negative, positive, or moderate attitude).

Because our dependent variables (knowledge and levels) were ordinal, we applied cumulative link models, also known as ordinal regression models. To account for the pairwise aspect of the data and possibility of correlation effect on the dependent variable levels, we used a PLUM (Polytomous Universal Model) ordinary regression model. The Zip Code of residence was set as random intercept in each model to denote contextual effects and a possible group effect. Covariates on interest include sex, education status, marital status, employment status, median household income, and home ownership. The likelihood ratio statistic, with chi-square statistic were used to select the final model using an automated step function. The data were analyzed using IBM SPSS statistics V.26.0 (IBM, Armonk, NY, USA). The level of statistical significance was set at p < 0.05.

Characteristics of sample

Of the 422 solicited households, 290 households completed the surveys (76.3% participation rate). The median age of respondents was 49.5 years (SD = 14.79). More than half of respondents were females (57.2%), and 49.0% were Black or White (29.0%). A bachelor’s degree was the highest level of education attained by 33.4% respondents, 30.3% had a graduate or professional degree, and 18.3% had attained an associate degree or a high school diploma (5.9%). Of the respondents nearly half (45.9%) were married, and 29.3% were single or never married, owned homes (63.5%), and 45.5% reported living in single-family homes. Among the respondents, over half (51.0%) were employed fulltime, and median household income for more than one-third (36.9%) of respondents was over $75,000 (36.9%), followed by those earning between $20,000 and $49,999 (30.3%). Additionally, respondents indicated that it was very frequent (25.9%) or frequent (16.9%) as well as occasionally (40.3%) to experience mosquito bites (Table 1).

Illegally used vehicle tire sightings and preferred methods of communication

Over half (53.1%) of respondents had seen an illegally discarded vehicle tire (s) on dead end streets, under bridges (47.2%) and/or on unoccupied, private properties (42.8%) (Fig. 1). Figure 2 provides an overview of the preferred sources of public health information. Most respondents preferred to receive public health information via the television (60.3%), internet (47.2), radio (44.5%) or billboards (44.1%). None of the sources of information were statistically significant between the two household median income levels.

Knowledge of mosquito-borne disease transmission and tire disposal

The differences between knowledge measures and median household income levels are highlighted in Table 2. Nearly eight in 10 respondents (78.3%) knew that mosquito-borne diseases can be spread through the bite of mosquitoes, and almost half of respondents did not know that mosquitoes can breed in polluted water. In addition, almost two out of three (64%) respondents indicated not knowing that the City of New Orleans will pick up to four tires placed next to garbage cans from properties eligible for garbage collection by the City, every second collection of the week for properties outside of the French Quarter/DDD and on Wednesdays for properties inside of the French Quarter/DDD. Only 2.9% of high median income households and 1.1% of low-income respondents achieved at least 80% on the knowledge score or answering at least one correct answer (good knowledge, p < 0.001).

Attitude towards source reduction and mosquito control

Table 3 summarizes respondents’ attitudes regarding source reduction and mosquito control. Almost all (95.5%) respondents strongly agree or agree that mosquitoes are a serious disease. Thus, about 70.4% of respondents and 94.3% of respondents strongly agree or agree that spraying and mosquito control can prevent mosquito populations and disease. Most of the respondents (81.7%) also acknowledged responsibility to control mosquito breeding in their yards while about half, 51.1% of the respondents believe it is the city’s responsibility to control mosquitoes. Respondents’ overall attitude towards illegal tire discarding and source reduction differed significantly by median household income (p < 0.05); compared to low-income respondents, those with high-median household income 31.6% vs. 35.2% had negative attitude, 30.4% vs. 31.8% had positive attitude and 37.3% vs. 31.8% had moderate attitude.

Surprisingly, when asked about how likely respondents are to report an illegal tire dumping, more than one in three respondents (34.0%) indicated not likely, and about 20.0% of respondents indicated somewhat likely to report an illegally used vehicle tire dumping. Similarly, 42% of the respondents indicated they were not willing to participate in a volunteer program to pick up used vehicle tires during neighborhood tire clean-up initiatives (Results not shown).

Preventive measures against source reduction and mosquito bites

Table 4 shows that most respondents (81.0%) believe that using mosquito repellents is the best preventative measure for the prevention of mosquito bites. Eliminating standing water around the house (84.8%) was the commonly practiced measure for source reduction. Regarding preventative scores, 19.1% of the respondents achieved at least 80% on the preventative practice score (good preventative practice), and only 20.5% obtained at least 80% on the for preventative practice score for source reduction (good source reduction).

Predictors of knowledge and attitude levels (good vs. poor; positive vs. negative)

Table 5 presents the ordinal logistic regression analysis of the relationship between knowledge, attitudes, and respondents’ socio-economic variables. This table reveals significantly high knowledge regarding mosquito control and illegally discarded vehicle tires if a respondent was employed (OR: 1.00; 95% CI [0.000–0.006]), when all the other variables in the model are held constant. Similarly, we found increased odds of having a positive attitude if respondents owned their home (OR: 1.00; 95% CI [0.00–0.003]). All other variables are not significant.