Introduction

In Chad, malaria is endemic across most regions with areas at risk of epidemics. It remains the main cause of consultation at health facilities and hospitalizations [1]. In 2017, one study found the malaria prevalence of 7.7% in general population and 8.8% in children aged 59 months in the Sahelo–Saharian region of Chad [2]. Another study found in the same region a malaria prevalence up to 30% among the nomadic population [3]. Due to their lifestyle, nomadic populations are highly exposed to malaria [4]. In addition, because of their living environment (near settlements or on the islands of Lake Chad) [5], their temporary area of living in the south of the country [6] and their lack of immunity to malaria [7, 8] nomads are much more exposed to malaria than the settle population.

To tackle malaria dynamic by reducing its related morbidity and mortality, a number of interventions including vector control, chemoprevention, and improved access to diagnostic tests and treatment, have been implemented as part of the national policy against malaria [9]. With the aim to reduce barriers to health interventions, the policy insists on free-of-charge access to essential interventions against malaria including prevention, diagnostic, case management and communication for behavior change. The policy provide guidance for developing a specific health strategy for isolate population including nomads. Thus, the National Health Program in charge of nomads advocated for improving access of nomads to health interventions [10].

The national policy against malaria has highlighted that all malaria interventions should include communication for behavior change related to the good and regular use of long-lasting insecticide-treated nets (LLINs), adherence to indoor residual spray, Seasonal malaria chemoprevention (SMC), the attendance at antenatal consultation (ANC), Intermittent Preventive Treatment (IPTp), and the early attendance at health facilities in case of first symptoms of malaria.

Among malaria prevention strategies adopted in Chad, intermittent preventive treatment has been shown to be effective in preventing malaria among pregnant women elsewhere [11]. In addition, SMC with sulphadoxine-pyrimethamine and amodiaquine (SPAQ) has been proven to be effective in preventing seasonal malaria among children aged 3–59 months in the Sahel region of Africa [12–19]. SMC programmes have been rolled out, targeting children aged 3–59 month across the Sahel region of Chad. IPTp is also administered to pregnant women from the fourth month of pregnancy during their antenatal care in health facilities. The distribution of LLINs has proven to be most promising [20], and highly cost-effective in preventing malaria cases among children [21] and pregnant women [22]. In Chad, LLINs are primarily distributed through mass campaigns every three years, and routinely at health facilities for pregnant women during their first ANC and for children aged 0–11 months during routine vaccination [9]. The last mass LLIN distribution campaign in Chad occurred in 2020.

In nomadic settings, children often receive SMC only when they are living temporarily in the Sahel region during SMC implementation. Sometimes, they are excluded from SMC as they are often uncounted during census enumeration [23]. Regarding IPTp, nomadic women face geographical barriers to accessing antenatal clinics, or feel excluded from services available in the locations where they take up temporary residence [6, 24]. Concerning LLINs, mass distribution campaigns have no strategy for enumeration of nomadic populations. In addition, nomads may not receive LLINs during routine distributions since they frequently travel in remote areas; they may have infrequent contact with the health system, sometimes only when an illness has progressed to an advanced or serious condition [25]. However, anecdotal suggest that most nomads purchase mosquito nets themselves which indicates a potential for its use [26].

Though, ownership of LLINs does not guarantee their use due to behavioral factors [27]. Evidence shows that, LLIN use is driven by users’ knowledge, the household’s economic status, the size of household [27, 28], the rainy season and presence of mosquitoes [29–31]. The identification of factors which predict demand for mosquito net among nomads would allow the National Malaria Control Program (NMCP) to tailor interventions to control malaria among this group and meet their specific needs.

In Chad, nomads represent 3.5% of the population [32]. They live mainly between the Saharan and Sahelian zones of the country. Nomads move with their flocks to find pasture and water; although they have more permanent dwellings in the north, spend dry seasons in the comparatively wetter south and, return north at the beginning of the rainy season (mid-April–May). A large number of pastoralists move with their herds from southern regions with high malaria transmission zones toward the provinces of Chari Baguirmi and Hadjer Lamis. Following climatic [33], economic [34] and political [35] changes over the past decades, a considerable increase in pastoral mobility has been recorded in the Sudanian zone [36].

Theories of health behavior change show that the knowledge about the causation, transmission, prevention and treatment of malaria may facilitate changes in attitude, resulting in the adoption of positive preventive practices that can reduce the risk of exposure to malaria [37]. Thus, understanding local factors affecting the perception of the causes and modes of transmission of malaria [38], and prevention practices [39–45], is key to inform strategies to reduce nomads’ risk of malaria and associated morbidity and mortality. However, previous studies on malaria in nomadic communities in Chad have mostly focused on the epidemiology of the disease, and very limited evidence is available on the level of knowledge of malaria and its associated factors. In addition, little is known about the coverage and use of mosquito nets. In order to provide evidence to inform efforts by the Chadian Ministry of Health and partners to tailor interventions for nomadic communities, this study aimed to identify factors associated to the knowledge about malaria and LLIN practice among the main nomadic groups in Chad. Our motivation for conducting this study at this time was to inform policy decisions to tailor interventions to control malaria among this group and meet their specific needs relating to LLINs.

Methods

Results

Sample characteristics

A total of 278 surveyed participants aged 20–65 years were included in the study. Basic socio-demographic characteristics of the participants are presented as frequencies and percentages in Table 1. Most participants were male (68.0%), married (92.4%) and, aged above 40 years (56.5%), with age distributions varying significantly by nomadic group (Table 1). A majority of the households had more than six members (92.3%) and less than three children under five years old (71.9%). The number of children under five years, the marital and economic status varied significantly by nomadic group with a higher proportion of Daza being categorized poor than other groups.

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Table 1. Socio demographic characteristics of survey participants by nomadic group, frequency (%).

https://doi.org/10.1371/journal.pone.0266900.t001

Malaria–related knowledge and associated factors

A majority of the respondents (77.0%) reported that malaria occurs mostly during rainy season July–September. Contrary to the Daza group, Arab and Fulani respondents reported that malaria is also more frequent at the beginning and end of the rainy season spanning June–October. The period of high transmission of malaria reported by participants were significantly dependent on nomadic group. In Table 2, nomad groups reported that groups most at risk of malaria are children under five years (86.0% of respondents) and pregnant women (73.0%). The groups most at risk of malaria reported varied significantly by nomad groups (Table 2).

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Table 2. Reported knowledge of malaria and practice by nomadic group, frequency (%).

https://doi.org/10.1371/journal.pone.0266900.t002

Regarding causes of malaria, 68.3% of respondents correctly reported that mosquito bites could cause malaria. While a high proportion accepted that environmental factors such as water (61.5% of respondents) and heat/sun (31.7%) can be the main cause of malaria. Other nomads surveyed reported that poor nourishment (hunger for 42.4%, food for 38.5%), and a low proportion of respondents mentioned religious or supernatural forces (4.7% for destiny/fate/act of God and 7.2% for magic/witchcraft) as the primary cause of malaria. Mentions of environment and poor nourishment as cause of malaria varied significantly by nomad groups.

Moreover, a majority of respondents were able to identify the main symptoms of malaria. Symptoms of malaria reported varied significantly by nomad ethnic groups (Table 2).

Of the socio demographic characteristics of nomads surveyed, ethnic group (OR: 4.58, 95% CI: 0.98–21.48) and possession of a LLIN (OR: 13.75, 95% CI: 1.83–103.20) were significantly associated with knowledge of malaria. Fulani respondents were five times more likely to have a good knowledge of malaria in comparison to Arab respondents, while households possessing a LLIN were 14 times more likely to have a good knowledge of malaria than households without LLINs (Table 3).

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Table 3. Factors associated with knowledge of malaria among nomads.

https://doi.org/10.1371/journal.pone.0266900.t003

After adjusting for others socio-demographic characteristics, ethnic group and the possession of a LLIN were significantly associated with the good knowledge of malaria (Table 3). In comparison with Arab respondents, Fulani respondents were five times more likely to have a good knowledge of malaria (AOR: 5.00, 95% CI: 1.04–24.03). In addition, after adjustment for socio-demographic variables, ownership of a LLIN was independently associated with malaria knowledge. Households with a LLIN were 10 times more likely to have a good knowledge of malaria than households without LLINs (AOR: 9.66, 95% CI: 1.24–75.36).

Mosquito net knowledge, ownership and use

Regarding knowledge of mosquito nets, 79.9% of respondents were aware of mosquito net as means to prevent mosquito bites. Furthermore, 91.4% of nomadic households surveyed owned at least one mosquito net, with 32.0% owning at least one LLIN. However, 87.1% of respondents (95.3% of respondents owning a mosquito net) reported sleeping under a mosquito net the night before the survey. Around half of respondents (54.3%) reported going under a mosquito net late from 19:00 or after. The ownership and use of mosquito net varied significantly by nomad ethnic groups (Table 2).

The socio demographic characteristics of nomads surveyed such as ethnic group, the head of household’s marital status, the number of household members and that of children under five years, the knowledge of malaria and the economic status of household were associated to the use of LLINs (Table 4). Daza respondents (OR: 0.16, 95% CI: 0.07–0.37) were one-sixth times more likely to use LLINs compared with Arabs. Monogamous households (OR: 0.37, 95% CI: 0.20–0.72) were around one-third times more likely to use LLIN in comparison to household lead by a widowed or divorced. Large households were more likely to use LLINs; in comparison to households with less than six members those with 9–11 members were around twice as likely to use LLINs (OR: 2.01, 95% CI: 0.93–4.35), and those with over 12 members were around six times more likely to use LLINs (OR: 6.07, 95% CI: 2.28–16.15). Households with more than two children under five years were twice as likely to use LLINs in comparison to households with 1–2 children under five years (OR: 2.05, 95% CI: 1.18–3.55). Respondents with a good knowledge of malaria were 13 times more likely to use LLINs than households that do not have a good knowledge of malaria (OR: 13.27, 95% CI: 1.77–99.63). In comparison to poor households, those with middle economic status (OR: 2.01, 95% CI: 0.93–4.35) and wealthier households (OR: 6.07, 95% CI: 2.28–16.15) were more likely to use LLIN (Table 4).

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Table 4. Factors associated with the use of LLIN among nomads.

https://doi.org/10.1371/journal.pone.0266900.t004

When adjusted for other socio demographic characteristics and knowledge of malaria, ethnic group, number of household members, economic status of household and knowledge of malaria were significantly associated with the use of LLIN by nomads (Table 4). Daza respondents (AOR: 0.23, 95% CI: 0.09–0.56) were around one quarter as likely to use LLINs in compared with Arab respondents. In comparison to households with less than 6 members, those with 6–8 members (AOR: 2.20, 95% CI: 1.03–4.74), those with 9–11 members (AOR: 3.62, 95% CI: 1.44–9.05) and those with more than 11 members (AOR: 6.68, 95% CI: 3.19–14.01) were more likely to use LLIN respectively. In comparison to poor households, the middle (AOR: 2.78, 95% CI: 1.17–6.62) and rich households (AOR: 6.68, 95% CI: 3.19–14.01) were more likely to use LLIN. In addition, households that have a good knowledge of malaria (AOR: 12.77, 95% CI: 1.58–102.99) were 13 times more likely to use LLIN (Table 4).

Discussion

This study assessed levels of malaria knowledge and factors associated with mosquito net use in the three main nomadic ethnic groups of Chad. Results show that in general nomads surveyed were aware of malaria risk and they reported the rainy season (July–September) as period of high transmission. However, depending on their position at the beginning or end of rainy season, their perception of risk varied. For example, Daza respondents who mostly live in areas where rainy season starts lately and ends earlier, perceived less risk of malaria in June and October compared with Arab and Fulani who leave the Sudanian zone later in the year. However, more investigation is required to ensure that nomads are not perceived malaria as a seasonal disease which can be a limit to the control of the disease.

Good knowledge of period of high transmission in the rainy season may lead nomads to attribute malaria cases to environmental factors such as water and heat/sun. Regarding the heat or sun, its association to malaria cause may be due to the intermittent fever of malaria manifestations as stated in others studies [51]. Regarding spiritual influences on perception of malaria, few nomads surveyed associated malaria with religious or supernatural forces which is the contrary to the results from others studies [51]. This situation may be due to community experiences of malaria case management since it is the most common reason for seeking health care in health facilities [1].

In contrast to knowledge of causes of malaria, participants had a good knowledge of its symptoms. Around nine out of ten nomads surveyed (90.67%) had a good knowledge of malaria with score above 2.5. The main factor associated with knowledge of malaria was the ethnic group with Fulani respondents more likely to have a good knowledge of malaria. An informal discussion with an officer in charge of vaccination of nomads suggest that among nomad ethnic groups, the Fulani group is that frequently seek for health facilities and that adhere more to immunization interventions. Thus, this nomadic group may benefit from health communication at health facilities than others groups.

In addition, the ownership of LLIN was associated to the good knowledge of malaria. This result can be explained by the effect of communication during the distribution of LLIN as most of LLINs may be received in the health center by pregnant women during their first Antenatal Consultation (ANC) or by children from 0–11 months during routine vaccination.

Most nomadic households surveyed owned at least one mosquito net (91.4%), although less than half of households surveyed (32.0%) owned at least one LLIN even though the survey happened 1–2 months after the LLIN mass distribution campaign. The coverage of LLINs among nomads was low in comparison to others studies in the general population in Chad, for which coverage has been estimated at 67.1%– 73.4% [2, 46]. The low coverage of LLINs among nomads can be explained by the lack of availability of that type of mosquito in local markets; most purchase mosquito nets themselves due to the fact that their communities are not included in census enumerations of the LLIN campaigns. In addition, most of them may miss the opportunity to receive LLINs from the routine distribution because of their frequent travel in remote areas which reduce their contact with the health system [25]. This result highlight the necessity to improve the availability of LLINs to nomadic community as they are at higher risk of malaria in comparison to the settled population [3, 52]. In addition, the improvement of availability of LLINs should go alongside with others malaria interventions such as ITPp and SMC for which only 22.1% of nomadic women have received at least one dose during their last pregnancy and 22.7% of nomadic households have received a visit by distributors (Table 2). This is particularly important since the national policy against malaria requires specific strategies for the nomadic population [9]. However, neither the former strategic plan against malaria mentions this specifically [53], nor has the strategic plan of the National Health Program for nomads was developed.

On the contrary to the knowledge of SMC (7.9%) and ITPp (5.8%) as preventive method for malaria, the overall level of malaria knowledge and the awareness of mosquito net as preventive method for malaria were good. In addition, as highlighted by theories of health behavior change [37], both ownership of mosquito net and the knowledge have been translated into its use. These results are in concordance with findings from other studies that demonstrated the association between malaria knowledge with preventive behaviors’ related to malaria in sub–Saharan Africa [27, 28]. However, more than half of nomads surveyed go under mosquito net later than the recommended time. An informal discussion with nomad respondents show that mostly they are busy with outside routine activities before 7PM: coming home with herds around 6PM, following by the extraction of milk and feeding younger animals. Generally this routine ends after 7PM. However, this finding shows the necessity to improve quality of information provides to nomadic communities on the mosquito net use. Such information should retain the prayer time of 6PM as the time for groups most at risk (pregnant women and children) to go under nets since almost all nomads are Muslim [54].

The results of the multivariate logistic regression highlights that nomadic ethnic group, number of household members, economic status of household and knowledge of malaria were the main factors associated with the use of mosquito net in nomadic settings. The greater the number of household members is the more likely for them to use a mosquito net. This result is contrary to those find in Zambia and Zimbabwe where the use of LLIN decreased as household size increased [27]. This contrast can be explained by the expected household expenditure on malaria case management; nomads may not benefit from free-of-charge healthcare provision since they frequently travel in remote areas which reduce their contact with the health system [25]. Thus to avoid expect expenditure for malaria case management, large households may feel encouraged to use LLINs than the small household who can handle this; small household may have a large financial resources per household member.

In comparison to poor households, the middle and wealthier households were more likely to use LLINs. This result is concordant with those of other studies [27, 55]. Results can be explained by the ownership of nets since 92.6% (30.2% for LLIN) and 94.6% (49.1% for LLIN) of respondents from middle and wealthier households declared owning at least one mosquito net, whereas this proportion is 87.5% (16.5% for LLIN) for poor households. Poorer households may face financial barriers to accessing mosquito net as most nomads mentioned buying mosquito net themselves. This result highlights the urgent need for NMCP to distribute LLINs to nomadic groups through teams comprising members of nomadic communities, as suggested elsewhere [56, 57].

In addition, Daza respondents were less likely to use LLIN in comparison to Arabs. This result can be explained by the fact that only 10.7% of Daza respondents own at least one LLIN in comparison to Arab (41.0%) and Fulani (41.6%). In addition, Daza respondents were the more poor (54.8%) than other respondents (32.4% Arab and 36.0% Fulani). This finding highlighted that the Daza nomadic group is most urgently in need to be targeted by LLIN mass distribution campaigns for the purpose of public health and equity of access to health interventions.

Although malaria interventions should be sensible to gender, in this study as elsewhere, we did not found an association between gender and respectively knowledge of malaria [58] and the use of LLINs [27, 59]. However, the aim of this study was not to assess the sensitivity of malaria interventions to gender, thus the survey sampling was not powered to integrate the gender aspect. Therefore, further studies may explore how gender norms and roles may influence the optimal design of policies and interventions aimed at improving nomadic communities’ malaria prevention practices. In the meantime, regarding the potential for women to influence positively the practice of malaria preventions [60, 61], it remains important to improve nomad women’ awareness of malaria and to tailor malaria prevention considering gender.

Conclusions

This study revealed good overall knowledge of malaria among nomadic communities, although there is a need to improve awareness of Plasmodium falciparum-carrying mosquitoes as the vector for malaria transmission. The rate of LLINs ownership was moderate, and only a small proportion of respondents slept under LLINs during the previous night before the survey. Thus, in comparison to the settled population, nomads are at higher risk of mosquito bite and hence acquiring malaria infection. This study also revealed that the main factors associated with use of mosquito nets included the nomadic ethnic groups, the number of household members, the economic status of household and the knowledge of malaria. Further progress in malaria prevention can be achieved by improving nomads’ access to LLIN mass distribution campaigns, and the quality of health information provided to nomad communities; such information can be delivered through the nomads community networks. This study can inform the National Health Program for nomads to design policies to improve nomadic communities’ knowledge of malaria prevention and promoting LLIN use as requested by the national policy against malaria.

Supporting information

Acknowledgments

The authors express their gratitude to the study participants who shared their views and experiences on malaria and preventive interventions. We acknowledge contributions of Kabo Karadjom, Bianzoumbé Jonas and Issa Younous for data collection.