Determinants of hanging and use of ITNs in the context of near universal coverage in Zambia

Abstract

Roll Back Malaria recently recommended a policy of universal coverage with insecticide-treated nets (ITNs) so that all age groups can benefit from protection against malaria. Countries adopting the ‘universal access’ policy include Zambia. Policy implementation in many settings involves mass distribution of free ITNs to achieve a measure of universal coverage. This study examines ITN deployment and use in the context of mass distribution efforts towards achieving universal coverage in a malaria-endemic district in Zambia. We use multiple logistic regression to identify predictors of ITN deployment and use by anyone in the household and by children under five.

Among ITN-owning households with a child under five, 69% used at least one ITN the night before the survey. About half of those children (54%) in ITN-owning households were covered the previous night. A strong and consistent predictor of use is household deployment of at least one ITN. Just over half of all ITNs were observed hanging, and reported use of nets for purposes other than malaria prevention was only 3%. Net characteristics, including shape, colour and whether or not the ITN was purchased, were not associated with net deployment. However, ITNs in poor condition are more likely to be observed hanging than ITNs in new or good condition.

In the context of free mass distribution of ITNs, behaviour change communication and activities are necessary to improve use. Results suggest campaigns and messages that persuade recipients to hang up their ITNs would contribute towards closing the gap between ownership and use.

Malaria, evidence-based policy, behaviour change, bed nets

KEY MESSAGES

• People who hang nets are most likely to use them, but half of the insecticide-treated nets (ITN) in an area which has seen a significant mass distribution have not been hung.

• Anecdotal reports that nets are being used for alternative activities are not borne out by the study findings, and neither is the idea that people only use nets if they purchased them, or have their preferred colour or size of net.

• ‘Hang-up’ campaigns and focused messages should accompany mass distribution campaigns to maximize ITN use in the community.

Introduction

Insecticide-treated mosquito nets (ITNs) are an effective tool to prevent malaria morbidity and mortality among children in Plasmodium falciparum malaria transmission settings (Lengeler 2004). In 2007, the World Health Organization (WHO) recommended that countries provide ITNs for all age groups at risk of malaria; and by 2008, 23 countries in Africa had adopted this recommendation as policy (WHO 2009). Countries adopting the ‘universal access’ policy include Zambia, which initiated universal coverage as early as 2005 in some districts. Implicit in the promotion of universal coverage as a goal is the recognition that ITNs, even if underused in some households (Korenromp et al. 2003; Eisele et al. 2009), can still have a ‘knock-down effect’ on mosquito densities, resulting in a community-level protective effect (Howard et al. 2000; Gimnig et al. 2003; Hawley et al. 2003; Killeen et al. 2007).

Several key assumptions about deployment (or hanging) and use by those who own nets underlie the recent and rapid distribution of ITNs in Africa. The intervention was assumed to be a known and popular one, so that fast and near universal uptake would arise because (1) the intervention is known to work (protect from malaria); (2) ITNs are virtually side-effect free; (3) ITNs are relatively cheap/free; (4) ITNs are easy to use (i.e. to hang and to sleep under), and (5) ITNs not only protect against disease but also provide relief from nuisance-biting mosquitoes (Lengeler 2004; Hanson et al. 2009). To benefit from ITNs for prevention of malaria, at either the individual or the community level, requires not only household ownership but also use, or at least deployment.

While there is evidence that behaviour change related to the uptake of ITN use is occurring, it is not universal. Data from a review of ITN use among 15 African countries between 2003 and 2006 showed that between 29 and 64% of children in households with ITNs were not sleeping under an ITN the previous night (Eisele et al. 2009). However, little is known about deployment and use when a policy of universal coverage is adopted (i.e. recommendations that everyone at risk of malaria, adults and children in endemic areas, should sleep under an ITN). We hypothesize that the gap between ownership and use may be as large or larger under this recommendation for universal coverage, although we need to understand this gap and advise health programmes accordingly.

This paper explores factors that affect deployment and use of nets in the context of near universal coverage of ITNs in households; we also present reasons why, despite having access to ITNs in Luangwa District (a malaria-endemic region of Zambia), some children and adults are still not using them. We conclude with implications for countries moving towards implementing the policy of universal coverage.

Background

A fundamental determinant of ITN use is household possession of ITNs; if you do not have one, you cannot use one. In sub-Saharan Africa, considerable effort has been spent on increasing the number of households possessing ITNs; there has been an impressive distribution effort by malaria control programmes, with significant government and donor support over the past few years. Many countries have increased household coverage to a point where average household coverage with at least one ITN has risen from 5% to 31% over the past 5 years (WHO 2009). In 2008, 13 of the 35 highest burden countries reported at least 50% of households in malaria endemic areas owned an ITN, although there is evidence that ownership does not translate into use at the same rate (Korenromp et al. 2003; Eisele et al. 2009). As the WHO position statement on ITNs suggests: ‘many people who received ITNs did not sleep under them, re-sold them, reduced their efficacy through inappropriate washing practices, or failed to replace them when they became damaged or torn’. While at present there are few data to back these statements, this question of non-use continues to challenge malaria practitioners in Africa.

Two recent analyses of national data of ITN use found that intra-household access to ITNs (i.e. ITN to occupant ratio) was one of the main drivers for ITN use, and that the lower the ratio, the higher the non-use among occupants (Eisele et al. 2009; Khan et al. 2009). Other than ownership, primary barriers to ITN use cited include: insufficient knowledge by users of the link between mosquito bites and malaria; lack of knowledge of ITN use as a preventive measure against malaria; and lack of knowledge as to who should be the main users of nets (Belay and Deressa 2008; Hanson et al. 2009). Some studies report poverty as a barrier to use, in that poorer households have immediate needs including food, water and medical care, and therefore sell nets to meet their basic needs (Bernard et al. 2009; Goesch et al. 2007). Likewise, the poor may store ITNs, rather than use them, for future sale or use (Goesch et al. 2007; Githinji et al. 2008; Hanson et al. 2009). Others believe recent illness, or death, may increase usage (at least temporarily), and proximity of a household to a health service delivery point may increase the likelihood of hearing messages related to the importance of net use (Bernard et al. 2009; Toe et al. 2009). In some settings, other socio-demographic factors may influence use, including education level and age of household head or adults in household; number, age and level of crowding in a household; and occupation or migration patterns of adults in a household (Macintyre et al. 2006; Noor et al. 2006; Noor et al. 2007).

In recent years, anecdotal information suggests some people use ITNs for purposes other than malaria protection. These reports suggest that some ITNs may be used as fishing nets (Zambia Times 2008); for protection of seeds and fruits against insects, as used by adults who work seasonally away from home in mosquito-ridden areas (pers. comm. J Ross, Lusaka, April 2009); or are being modified for personal protective gear and luxury items such as wedding veils (Zambia Times 2008). Finally, reports from the Red Cross of Kenya (pers. comm. Moses Kiranguru, 2008) suggest householders save new nets for visitors. While saving a net for future use is not direct misuse, it could be construed as misuse if there are current residents unprotected in the household. Although these anecdotes are worth investigating, evidence from surveys continues to show that relatively few nets are being misused (Githinji et al. 2008).

There is a perception that the delivery mechanism (i.e. whether the net is free at point of access or not, or where the net comes from) is important to acceptance and use of an item in the household (Webster et al. 2007; Webster et al. 2008; Cohen and Dupas 2007). Roger’s theory of the Diffusion of Innovations supports this premise (Roger 1984) under the aegis that where an ITN comes from (e.g. government/Ministry of Health, the market, a non-governmental organization etc) or even the brand of net, may affect the level of trust that the community places in that product. The agent who introduced the ITN [the community health worker (CHW), friend, nurse or merchant] may also influence net use (Noor et al. 2007).

Net characteristics such as brand, colour or size may also influence uptake and use. Many caretakers report that children get too hot or fear sleeping under the nets (Alaii et al. 2003). There is some evidence that pregnant women, who have to get out of bed frequently in the middle of the night to relieve themselves, find hung nets inconvenient (Gabrowsky et al. 2007; Belay and Deressa 2008). This sense of inconvenience may also affect use by children. If nets become damaged or caretakers think the nets make children hot and disturb their sleep, they may decide to let children sleep without a net (Smith et al. 2007; Belay and Deressa 2008; Toe et al. 2009).

To achieve universal coverage of ITNs and maximum protection, several questions related to ITN deployment and use should be addressed. First, what level of ITN use can be expected among children, pregnant women and adults once universal coverage has been achieved? Second, what are the most important explanatory factors related to non-use? And lastly, are new messages related to knowledge of transmission needed?

Methods and materials

Site

This study took place in Luangwa District, Lusaka Province, Zambia. The district has a population of approximately 34 000 people and is defined as rural by the Zambian Central Statistics Office (CSO 2000). The district was chosen as one of the first to be targeted for rapid scale-up of ITNs, and from 2005–06, over 16 000 ITNs (2000 ITNs and 14 000 long-lasting ITNs) were distributed. The National Malaria Control Center (NMCC) and its partners used a combination of free mass distribution campaigns and free or subsidized routine distribution through antenatal care clinics to pregnant women and their children under 5 years. As a result, the proportion of all households possessing at least one ITN in 2008 was 73%, while the proportion of households with a child under five possessing an ITN was 81%. No indoor residual spraying is currently being done in Luangwa District. Fishing and small-scale agriculture are the predominant livelihood activities. The population is served by nine health centres. Malaria transmission typically occurs from December to June following the main rainy season, and parasite infection prevalence in children less than 5 years old was 7% in the peak transmission period in 2008 (Keating et al. 2009).

Data collection

Data for this study came from a household survey conducted during the peak in malaria transmission in April–May 2008. The Malaria Indicator Survey (MIS) protocol was followed to collect all household data (Zambia Ministry of Health 2008). Simple random sampling was used to draw the sample from a list of enumerated households created in March 2008. The sample included 737 children under five residing within 483 households. The eligibility variable for children to be part of the survey was age as all children under five were selected in each of the households. Data from mothers were collected for 650 of the 737 children; there was no guardian present for 87 children, so complete information on those children was not collected (Keating et al. 2009). Ethical approval was given by the Institutional Review Boards (IRB) of Tulane University, the University of Zambia, and the Partnership for Appropriate Technology in Health (PATH). Informed consent was obtained from all interviewees.

A standardized MIS-style household questionnaire was used to collect socio-economic data about the household. Data on mosquito nets owned by the household were collected using a net roster, including a listing of all household residents who slept under each net the previous night, and the brand, source, time since acquisition and time since last retreatment. Net characteristics, including colour, shape, observed condition and hanging status, were recorded by interviewers upon observation. A questionnaire was administered to women aged 15–49 years in the household. The questionnaire included socio-demographic information and data on mothers’ malaria-related knowledge, practices (e.g. regularly covering children with an ITN at night), exposure to malaria messages, mosquito net preferences (e.g. net shape and colour) and alternative uses of nets.

Data analysis

Data were analysed using Stata 10.0 (Stata Corporation, College Station, Texas). The following primary outcomes within ITN-owning households were investigated: (1) deployment of ITNs among households with at least one child under five; (2) households with anyone using an ITN; and (3) ITN use among children under five. Nets owned by the household were classified as ITNs or untreated nets according to the Roll Back Malaria (RBM) definition (RBM 2000).

Chi-square tests were used to quantify the difference in primary outcomes among household, mother, child and net characteristic categories. Logistic regression was used to assess relationships between explanatory variables and the three primary outcomes, while controlling for potential confounding factors. Robust standard error estimations were used in the ITN deployment model to control for correlated data at the household level.

Household socio-economic status was measured with a wealth index of household assets (Rutstein and Johnson 2004). Dichotomous variables were created to indicate whether or not the household owned any ITNs that were purchased; recently acquired any ITNs (within the last year); reported having any ITNs that were hung by a CHW; and had any ITNs hung at the time of the interview. Condition of the net was assessed using the following definitions: good, no holes; fair, no holes that fit a torch battery;¹ poor, 1–4 holes that fit a torch battery; unsafe, ≥5 holes that fit a torch battery; unused, still in package; and unknown. ITN-owning households were classified as owning all ITNs in good or new condition; some ITNs in good or new condition; or no ITNs in good or new condition. Mother’s preferences regarding shape and colour of net were combined with information on characteristics of nets owned by the household to create dichotomous variables indicating ownership of mother’s preferred colour and shape.

Mother’s characteristics included education level (control factor), malaria-related knowledge and exposure to malaria communications messages. Two dichotomous measures of malaria knowledge were constructed: (1) knowledge of the correct cause of malaria (i.e. identifies correct cause and does not identify any incorrect causes); and (2) knowledge of mosquito nets as a method of protecting against malaria. Exposure to malaria communication messages was examined with respect to message content and communication channel. Dichotomous variables were constructed to indicate any exposure to messages about: (1) mosquito nets; (2) danger/threat of malaria; and (3) mosquitoes as the cause of malaria. Additionally, dichotomous variables were created to indicate any exposure to messages from: (1) government health facilities; (2) drama groups; (3) radio, television or posters; (4) interpersonal communication through a CHW, friend, family member or peer educator. Child characteristics considered in analyses examining ITN use by children under five include child sex (control factor) and age (control factor dichotomized as infants aged 0–11 months versus children aged 12–59 months).

We also measured the characteristics of the nets inside the households. These included: time since net was acquired, source, shape, colour, brand and condition, and dichotomous variables indicating whether or not the net was purchased, whether it was used last night and whether it was observed hanging at the time of survey.

Results

Overall, just over half (53.9%) of children under five were reported to have used an ITN the previous night, among those in ITN-owning households (Table 1). Among households with ≥1 ITN, over two-thirds (69.5%) reported that at least one person in the household slept under an ITN. Bivariate analyses of factors related to ITN use (Table 2) suggest that among all household members (χ²= 206.8, P < 0.001), as well as among children (χ²= 167.0, P < 0.001), having an ITN hung in the house is strongly associated with ITN use. ITN use among any household member and children under five generally increases with household socio-economic status (χ²= 11.1, P = 0.026 and χ²= 41.6, P = 0.006, respectively). We tested the relationship to use using the chi-square test for trend as applied to the household wealth data (see Table 2). Results show that for households with at least one person under an ITN the chi-square trend for wealth was 3.5 (P = 0.062), and for households with children under an ITN, the chi-square trend was 8.5 (P = 0.0036). Household ownership of at least one ITN per sleeping space is strongly associated with use among children under five (χ²= 12.1, P = 0.001), although no such association was found for use among any household member. ITN use is not associated with observed net condition or whether the net was purchased or obtained for free. Among the various malaria communications, only the measure of whether the respondent was exposed to messages about nets is associated with ITN use by any household resident (χ²= 6.07, P = 0.014) and by children under five (χ²= 3.90, P = 0.048). Correct knowledge of malaria transmission is associated with ITN use among any household resident (χ²= 6.24, P = 0.012) and among children under five (χ²= 5.89, P = 0.015). Other measures of malaria-related knowledge are not significantly associated with ITN use.

Table 1

ITN ownership and use among households and children under 5 in Luangwa District, Zambia, 2008

	n	%
Households with ≥1 child under 5	483	100.00
Owns ≥1 ITN	390	80.75
Owns ≥1 ITN per sleeping space	224	46.38
≥1 ITN hanging	283	58.59
1 ITN hanging per sleeping space	115	23.81
ITN use by ≥1 household member the previous night	271	56.11
ITN use by ≥1 child under 5 the previous night	233	48.24
ITN use by all children under 5 the previous night	198	40.99
Households with ≥1 child under 5 & ≥1 ITN	390	100.00
≥1 ITN hanging	283	72.56
1 ITN hanging per sleeping space	115	29.49
ITN use by ≥1 household member the previous night	271	69.49
ITN use by ≥1 child under 5 the previous night	233	59.74
ITN use by all children under 5 the previous night	198	50.77
Children under 5	737	100.00
Slept under an ITN the previous night	322	43.69
Children under 5 in a household with ≥1 ITN	597	100.00
Slept under an ITN the previous night	322	53.94

Table 2

Characteristics of ITN use by household and children, among households with at least 1 ITN in Luangwa District, Zambia, 2008

	Number of households	% households with ≥1 person who slept under an ITN the previous night	Test statistic	Number of children	% children who slept under an ITN the previous night	Test statistic
Household (HH) wealth
Lowest	87	57.47		152	42.76
Mid-low	79	68.35		116	62.93
Middle	57	66.67		81	54.32
Mid-high	74	75.68	χ2(4) = 11.08	103	50.49	χ2(4) = 14.58
Highest	93	78.49	P = 0.026	145	60.69	P = 0.006
Chi square trend test for wealth	390	3.475	pr > χ2 = 0.0623	597	8.475	pr > χ2 = 0.0036
HH has ≥1 ITN hanging
≥1 ITN hanging	283	90.11	χ2(1) = 206.83	436	69.95	χ2(1) = 166.96
0 ITNs hanging	107	14.95	P = 0.000	161	10.56	P = 0.000
HH owns 1 ITN per sleeping space
Owns	224	70.98	χ2(1) = 0.55	328	60.37	χ2(1) = 12.11
Does not own	166	67.47	P = 0.456	269	46.10	P = 0.001
HH owns an ITN obtained within the last year
Owns	234	73.08	χ2(1) = 3.56	349	59.31	χ2(1) = 9.77
Does not own	156	64.10	P = 0.059	248	46.37	P = 0.002
Condition of ITNs owned by HH
All ITNs in good or new condition	105	65.71		154	51.95
Some ITNs in good or new condition	92	70.65	χ2(2) = 0.97	151	49.67	χ2(2) = 2.60
No ITNs in good or new condition	193	70.98	P = 0.616	292	57.19	P = 0.273
Purchased ≥ 1 ITN
Purchased	214	71.50	χ2(1) = 0.90	324	53.40	χ2(1) = 0.08
Did not purchase	176	67.05	P = 0.342	273	54.58	P = 0.773
All HHs / children	390	69.49		597	53.94
Mother’s education
No education	41	63.41		62	56.45
Some primary	246	65.85	χ2(1) = 4.89	375	52.00	χ2(2) = 3.58
Primary plus	60	80.00	P = 0.087	89	62.92	P = 0.167
Exposure to messages – mosquito nets
Exposed	171	74.27	χ2(1) = 6.07	268	58.58	χ2(1) = 3.90
Unexposed	176	61.93	P = 0.014	258	50.00	P = 0.048
Exposure to messages – danger of malaria
Exposed	103	68.93	χ2(1) = 0.06	147	59.18	χ2(1) = 1.90
Unexposed	244	67.62	P = 0.811	379	52.51	P = 0.168
Exposure to messages – mosquitoes & malaria
Exposed	115	72.17	χ2(1) = 1.37	173	56.65	χ2(1) = 0.54
Unexposed	232	65.95	P = 0.242	353	53.26	P = 0.463
Exposure to messages – government health facility
Exposed	253	67.59	χ2(1) = 0.08	397	52.64	χ2(1) = 1.95
Unexposed	94	69.15	P = 0.782	129	59.69	P = 0.163
Exposure to messages – drama
Exposed	49	81.63	χ2(1) = 4.87	70	58.57	χ2(1) = 0.57
Unexposed	298	65.77	P = 0.027	456	53.73	P = 0.449
Exposure to messages – radio, TV or poster
Exposed	19	73.68	χ2(1) = 0.30	24	50.00	χ2(1) = 0.19
Unexposed	328	67.68	P = 0.586	502	54.58	P = 0.660
Interpersonal communicationa
Exposed	43	69.77	χ2(1) = 0.07	63	65.08	χ2(1) = 3.31
Unexposed	304	67.76	P = 0.792	463	52.92	P = 0.069
Knowledge – correct cause of malaria
Has knowledge	280	71.07	χ2(1) = 6.24	423	56.97	χ2(1) = 5.89
Does not have knowledge	67	55.22	P = 0.012	103	43.69	P = 0.015
Knowledge – prevention with nets
Has knowledge	285	69.82	χ2(1) = 2.41	432	54.63	χ2(1) = 0.06
Does not have knowledge	62	59.68	P = 0.121	94	53.19	P = 0.800
Owns mother’s preferred net shape
Owns	303	66.67	χ2(1) = 2.34	463	54.00	χ2(1) = 0.99
Does not own	38	78.95	P = 0.126	54	61.11	P = 0.320
Owns mother’s preferred net colour
Owns	156	69.87	χ2(1) = 0.45	227	57.71	χ2(1) = 1.44
Does not own	185	66.49	P = 0.504	290	52.41	P = 0.230
CHW hung an ITN in the home
CHW hung an ITN	29	65.52	χ2(1) = 0.09	43	53.49	χ2(1) = 0.01
CHW did not deploy	318	68.24	P = 0.764	483	54.45	P = 0.903

^aCHW, friend, family member or peer educator.

Only half the ITNs listed in the net rosters within selected households were observed as hanging² (Table 3), and 90% of those were reported as used last night by someone in the household. In households with at least one ITN, 55% were used the previous night. In households which had an ITN but had no ITN observed hanging, nearly 15% reported someone slept under an ITN the night before the survey. Nearly a third (32%) of ITNs were owned by the wealthiest households. Over half (54%) of the ITNs were obtained in the past 12 months, while over three-quarters were obtained in the past 24 months. Over 81% were obtained through the public sector, 9% through the private sector and 10% from an ‘other’ source. Half of the ITNs were purchased, either at a subsidized price or at full cost. Nearly three-quarters (73%) of the ITNs are long-lasting Permanets, and nearly all are rectangular (95%) and white (92%).

Table 3

Characteristics of ITNs, among ITNs owned by households with children under 5 in Luangwa District, Zambia, 2008

	% ITNs	n
Household wealth
Low	18.74	160
Mid-low	17.92	153
Middle	11.48	98
Mid-high	20.02	171
High	31.85	272
Months ago obtained
0–6 months	14.99	128
7–12 months	39.46	337
13–24 months	25.06	214
24–36 months	5.62	48
>36 months	10.89	93
Don’t know	3.98	34
Source
Government	81.03	692
Retail	9.25	79
Other	9.60	82
Don’t know	0.12	1
Purchased	50.23	429
Shape
Rectangular	95.43	815
Conical	3.98	34
Other	0.59	5
Colour
White	92.39	789
Green	5.39	46
Blue	2.22	19
Brand
Permanet	73.19	625
Olyset	0.23	2
Other long-lasting ITN (LLIN)	3.04	26
Safinet	2.34	20
Other pre-treated net	1.05	9
Other	11.36	97
Don’t know	8.78	75
Condition
Good	41.33	353
Fair	25.18	215
Poor	21.90	187
Unsafe	8.90	76
Unused	1.76	15
Don’t know	0.94	8
Used last night	54.68	467
Hanging	56.91	486
Total	100.00	854

After adjusting for potential confounding factors using logistic regression, the strongest predictor of use the previous night among children under five in ITN-owning households is deployment of at least one ITN [adjusted odds ratio (AOR) = 23.31, 95% confidence interval (CI): 12.57–43.21] (Table 4). Children living in households that obtained an ITN within the last year are nearly twice as likely to have used an ITN as those in households with older ITNs (AOR = 1.95, 95% CI: 1.23–3.09). Children living in households that own at least one ITN per sleeping space are also nearly twice as likely to have used an ITN than those living in households with less than one ITN per sleeping space (AOR = 1.87, 95% CI: 1.19–2.93). Children living in households that purchased at least one ITN are no more likely to have used an ITN the previous night than children in households where all ITNs were received free of charge (AOR = 0.94, 95% CI: 0.59–1.52). Other child, mother and household characteristics included in the model are not significantly associated with ITN use by children.

Table 4

Predictors of ITN use by children under 5, among children under 5 living in households with at least 1 ITN, Luangwa District, Zambia, 2008

	Adjusted Odds Ratio	95% Confidence Intervals
Child
Infant	1.05	0.63–1.77
Female	0.85	0.55–1.32
Household
Household wealth (Referent: lowest)
Mid-low	1.77	0.90–3.49
Middle	0.94	0.45–1.99
Mid-high	1.28	0.63–2.59
High	0.93	0.44–1.94
Purchased ≥1 ITN	0.94	0.59–1.52
Owns mother’s preferred shape	0.82	0.39–1.71
Owns mother’s preferred colour	0.79	0.50–1.24
Obtained an ITN within the last year	1.95**	1.23–3.09
ITN condition (Referent: All ITNs good/new)
Some ITNs in good/new condition	0.65	0.34–1.23
No ITNs in good/new condition	0.92	0.53–1.61
Household owns ≥1 ITN per sleeping space	1.87**	1.19–2.93
≥1 ITN hanging	23.31***	12.57–43.21
Mother
Education (Referent: no education)
Some primary	0.75	0.37–1.52
Primary or higher	1.23	0.51–2.94
Knowledge – correct cause of malaria	1.35	0.74–2.47
Message exposure – mosquito nets	1.40	0.90–2.17
Observations	517
LR χ2	LR χ2(19) = 197.67****
Pseudo R2	0.28

*P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001.

At the household level after controlling for potential confounding factors using logistic regression, deployment of at least one ITN is also the strongest predictor of ITN use by at least one household member the previous night (AOR = 78.38, 95% CI: 32.65–188.16) (Table 5). Households are about 2.5 times as likely to have had ITN used by at least one household member the previous night if a mother in the household had heard a message about mosquito nets (AOR = 2.66, 95% CI: 1.24–5.73). Ownership of at least one purchased ITN is not associated with ITN use (AOR = 1.39, 95% CI: 0.63–3.07). At the household level, we also examined reports of alternative uses for nets. Only 3% of households report using ITNs for purposes other than malaria prevention, such as fishing (data not shown).

Table 5

Predictors of ITN use by at least 1 household member, among households with at least 1 child under 5 and at least 1 ITN, Luangwa District, Zambia, 2008

	Adjusted Odds Ratio	95% Confidence Intervals
Household
Household wealth (Referent: lowest)
Mid-low	1.92	0.67–5.48
Middle	1.67	0.53–5.28
Mid-high	3.86*	1.23–12.11
High	1.31	0.38–4.49
Purchased ≥1 ITN	1.39	0.63–3.07
Owns mother’s preferred shape	0.77	0.22–2.67
Owns mother’s preferred colour	0.56	0.26–1.19
Obtained an ITN within the last year	2.02	0.94–4.33
ITN condition (Referent: All ITNs good/new)
Some ITNs in good/new condition	0.51	0.17–1.48
No ITNs in good/new condition	0.73	0.30–1.77
Household owns ≥1 ITN per sleeping space	0.84	0.41–1.74
≥1 ITN hanging	78.38***	32.65–188.16
Mother
Education (Referent: no education)
Some primary	0.92	0.32–2.63
Primary or higher	1.97	0.47–8.14
Knowledge – correct cause of malaria	1.30	0.49–3.48
Message exposure – mosquito nets	2.66*	1.24–5.73
Message exposure – drama	1.16	0.37–3.60
Observations	341
LR χ2	LR χ2(17) = 202.67****
Pseudo R2	0.47

*P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001.

Table 6 summarizes predictors of ITN deployment among households with at least one child under five. ITNs that were observed to be in poor condition are significantly more likely to be hung than ITNs in good or new condition (AOR = 2.11, 95% CI: 1.59–3.89) (Table 5). All other net characteristics, including shape, colour, source and whether or not the ITN was purchased, are not significantly associated with deployment. Levels of education, malaria knowledge and exposure to malaria messages among mothers are also not significantly associated with ITN deployment.

Table 6

Predictors of ITN hanging in the home, among ITNs owned by households with at least 1 child under 5, Luangwa District, Zambia, 2008

	Adjusted Odds Ratio	95% Confidence Intervals
ITN characteristics
Condition (Referent: good/new)
Fair	1.33	0.81–2.17
Poor	2.11**	1.59–3.89
Unsafe	1.23	0.61–2.50
Colour (Referent: white)
Green	0.59	0.27–1.30
Blue	0.89	0.30–2.66
ITN was purchased	0.88	0.60–1.29
Source (Referent: government)
Retail	0.75	0.33–1.69
Other	0.83	0.39–1.75
Months ago obtained (Referent: 0–6 months)
7–12 months	0.95	0.53–1.69
13–24 months	1.21	0.63–2.31
25–36 months	0.90	0.31–2.59
>36 months	0.83	0.39–1.80
Mother’s knowledge & exposure
Education (Referent: no education)
Some primary	0.88	0.45–1.73
Primary or higher	1.29	0.57–2.89
Knowledge
Nets protect	1.12	0.62–2.02
Correct cause of malaria	1.18	0.66–2.12
Malaria message exposure – channels
Government health facility	0.81	0.48–1.35
Drama	1.21	0.58–2.54
Radio, TV or poster	0.92	0.38–2.24
Interpersonal communicationa	1.48	0.73–2.98
Malaria message exposure – message
Importance of net use, who should  use nets	1.36	0.84–2.21
Malaria is dangerous, can kill	1.15	0.69–1.90
Mosquitoes spread malaria	1.12	0.67–1.89
CHW hung a net in the home	1.59	0.64–3.96
Observations	708
LR χ2	F(24, 311) = 1.35***

^aCHW, friend, family member, or peer educator

*P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001.

Discussion

We investigated factors related to ITN deployment and use by children and by at least one household member in Luangwa District, Zambia. Following free mass distribution of ITNs and the continued routine distribution of free or heavily subsidized ITNs through antenatal care in clinics in Luangwa, 81% of households with children under five possess at least one ITN (Larsen et al. 2010). Among children in ITN-owning households, use was low at only 54%. In nearly one-third (31%) of ITN-owning households with a child under five, none of the ITNs were used by any household member the previous night. Only about half (57%) of all ITNs were hung at the time of the survey. Among ITN-owning households, by far the strongest predictor of ITN use at household and child levels was deployment of at least one ITN. However, 10% of households had ITNs hanging up but no one was using them. But clearly if an ITN is not hanging, it is much less likely to be used (15% of households without a hanging net reported use of an ITN the previous night). Net ‘hang-up’ campaigns may be highly effective in increasing ITN use (IFRC 2009). CHWs have begun a net hang-up campaign in Luangwa District together with the provision of information on the importance of using ITNs.

As has been shown previously across 15 countries in Africa (Eisele et al. 2009), intra-household access to an ITN, measured here by the ratio of ITNs per sleeping space, is associated with higher ITN use among children. This implies that scaling up ITN distribution, including the target of covering all sleeping spaces with an ITN, will facilitate increased use among vulnerable populations. However, even if scale up and hang-up campaigns occur, it would seem that a gap of about 10% or higher of underuse remains.

Among various net characteristics tested, only ITN condition was identified as a significant predictor of deployment. ITNs in poor condition are significantly more likely to be hung than ITNs in good or new condition. Hang-up campaigns may be one avenue for facilitating use of ITNs in good condition and disposal/recycling of nets in poor condition. All other ITN characteristics, including shape and colour, were not associated with net deployment. The notion that people are more likely to use nets that they purchase (Cohen and Dupas 2007) is a primary rationale for social marketing of nets at subsidized prices. However, we find that ITNs received for free are no more likely to go unused than those that were purchased. It is clear that some ITNs provided through the government channels were being sold during 2007 and possibly early 2008. This is despite a national policy of free distribution for all government distribution channels by 2007. It is likely that adoption of this policy was slow in many areas. The cost-recovery scheme that the Ministry of Health and partners originally put in place for ITNs delivered through antenatal clinics provided some funding for district budgets. There may have been some resistance to halting this process at district or facility level.

Mother’s knowledge and her exposure to malaria messages were not associated with ITN deployment or use by children under five, although exposure to such messages was high in this sample. Although we find that generally exposure is not associated with positive preventive behaviour, the overall trend in the direction of coefficients is positive. The intensity of communication may be an important factor that was unfortunately not captured in this study (i.e. frequency of exposure, levels of exposure, familiarity with messages transmitted through specific communications campaigns).

Contrary to anecdotal evidence of ITNs used for alternative purposes such as fishing and wedding veils (Zambia Times 2008), our results suggest very little use of ITNs for purposes other than malaria prevention. In a context where households rely heavily on fishing for food and income, only 3% (14 of 467 households) reported using ITNs for other purposes including fishing. While there is likely some underestimation of ITN use for other purposes due to social-desirability bias among respondents, and because members of these communities may have been subjected to messages telling them not to misuse them, these results do not support the rumours of widespread ITN misuse, even when they are distributed free of charge.

Study limitations

Limits to this study include limited external validity to other areas where use may be much higher. So while our results may be generalizable to other areas in sub-Saharan African that have reached similar levels of coverage through free mass distribution, we would advise caution in extending the results to areas with other levels of coverage and/or coverage levels achieved through alternate methods. Social desirability bias could have affected responses to questions about the use of ITNs, falsely inflating findings on ITN use where respondents are reluctant to report non-use. Hanging status of ITNs could also suffer from social desirability bias where respondents report deployment of ITNs and interviewers fail to observe hanging status. We would have liked to analyse whether delivery channel (free mass distribution or free or subsidized antenatal clinic delivery) effected use, but the questionnaire limited our ability to understand if nets originating from facilities could be meaningfully attributed to either channel. Distribution of nets arriving at districts for either distribution channel often takes several months to complete and households likely received nets from both channels.

Conclusions

Universal coverage of ITNs in households as recommended now by RBM/WHO is a laudable goal and is increasingly being taken up by national malaria control programmes (WHO 2009). Our analysis shows that in one district of Zambia where the National Malaria Control Centre (NMCC) piloted mass distribution and has attempted to reach a very high level of coverage, the basic goal of ownership has been reached; over 80% of households with a child under five now own at least one ITN. Among these households, about half of the children did not use an ITN the night before the survey. The strongest factor affecting use appears to be presence of an ITN hanging in the house: of those ITNs that were hanging, only 10% were not used the previous night. This implies that hang-up campaigns may be an essential component of any mass distribution programme. Such campaigns could contribute significantly to closing the gap between ownership and use. Our data do not support anecdotal reports of widespread use of nets for alternative purposes.

Finally, while we are optimistic that if ITNs are hung, they tend to be used, there are still many unused ITNs in a district that has benefited from mass distribution of free ITNs (nearly 6880 ITNs, or 43%, were not hanging in Luangwa). Our data were limited in terms of how to explain the non-use, and we recommend (as other researchers have also done) more in-depth qualitative research be designed around use and non-use to further understand this behaviour (Webster et al. 2007). We recognize that it is frustrating that there are still few credible explanations to explain why half the ITNs in households with them are unused. The survey data clearly do not support the idea of widespread misuse or reselling, but clearer accountability of these nets is needed in the future. Policies based on the evidence that for every two ITNs distributed only one is used may not attract support and subsidies in the long term. Factors that facilitate or inhibit use must be identified and targeted through behaviour change communications and activities.

Funding

This research was funded by the Centers for Disease Control and Prevention (CDC) (1R18CK000102-01), by the PATH Malaria Control and Evaluation Partnership in Africa (MACEPA) and by Tulane University. The opinions described herein are those of the authors and do not necessarily reflect the official position or policy of CDC, Tulane University, PATH, or the Ministry of Health.

Conflict of interest

None declared.

Acknowledgements

The researchers thank the data collection team at the University of Zambia Masters in Public Health Program, as well as the communities in Luangwa District. We also thank the Zambian Ministry of Health and the NMCC for granting permission to carry out this research.

Endnotes

¹ During training, a standard size of torch was established amongst all interviewers to obtain consistent reporting of holes in nets and therefore of net quality.

² ‘Hanging’ and ‘deployment’, used interchangeably in this paper, refer to nets that were observed by the interviewers to be in a position above the sleeping space. They could have been tied up (as is common during the day) or hanging over the space in preparation for night-time protection. The word ‘deployment’ is often used in this context in the national malaria control programmes.