Malaria is a major global public health threat that continues to impact the well-being of people and nations. The 2021 Malaria Report of the World Health Organization (WHO) states that in 2020, there were 241 million cases associated with 627 000 deaths globally . This increase of 14 million cases compared to the 229 million cases that were reported in 2019 occurred one year after commencement of the COVID-19 pandemic and the resulting service disruptions [1, 2]. Most of the cases (95%) were from the WHO African region followed by WHO Eastern Mediterranean and South-East Asian region which had 2.4% and 2% cases, respectively . Malaria is caused by Plasmodium parasites, the most lethal and common in Africa being Plasmodium falciparum . Female Anopheles mosquitoes of a particular range of species are responsible for transmitting Plasmodium parasites to human hosts . Major malaria vectors in Africa are Anopheles arabiensis, An. gambiae and An. funestus [4, 5]. Several other Anopheles species are primary vectors in more limited geographic areas, while some species transmit malaria as secondary vectors . Anopheles arabiensis is the primary malaria vector in South Africa [7, 8]. It is zoophilic, preferring to feed on cattle but will also readily feed on humans, mostly outdoors where they prefer to rest [9, 10]. These attributes make it much more difficult to target An. arabiensis using conventional vector control tools such as insecticide-treated bednets (ITNs) and indoor residual spraying (IRS).
In South Africa, malaria transmission is seasonal and most intense in the warm rainy season, which is typically from September to May [11, 12]. There are three malaria endemic provinces, Limpopo, Kwazulu-Natal and Mpumalanga [13, 14]. Since 2003, Limpopo has experienced the highest annual number of malaria cases [10, 15]. The majority of cases in Limpopo Province occur in the Vhembe District which accounts for more than 60% of malaria cases reported in South Africa [11, 12, 16]. The primary malaria control strategy in the Vhembe District is IRS [12, 17]. The IRS coverage in the malaria-affected areas of Limpopo Province was between 85% and 90% over the period of year 2010 to 2014 [15, 17]. Despite annual implementation of IRS, the Vhembe District remains heavily burdened with malaria, strongly suggesting that suitable supplementary or new control methods should be identified for deployment [15, 18].
Vhembe District (Fig. 1) in Limpopo Province is in the far north of South Africa and borders with Zimbabwe, Mozambique and Botswana . Mozambique and Zimbabwe are high-transmission malaria-endemic countries and this contributes to the number of cases due to imported malaria, such cases setting up local foci for mosquito infection [13, 18, 20]. Vhembe is one of the least developed districts in South Africa with the greatest proportion of rural inhabitants . It has approximately 1.3 million people and it is estimated that 65% of the population lives in poverty [22, 23]. Malaria is recognized as a disease of poverty and is concentrated in poor areas . Poor housing structures without screened windows and doors in malaria-endemic villages increases contact between humans and mosquitoes, leading to an increase in malaria transmission .
The main activities in the Vhembe District include livestock and crop farming for subsistence purposes [26–28]. The district receives an average estimated annual rainfall of 820 mm . Over 70% of land in the Limpopo Province is suitable for grazing [26, 29]. A large number of households in the malaria-endemic rural areas of the Vhembe District own livestock [30, 31]. Livestock can provide a blood meal to a large number of malaria vectors including An. arabiensis . Therefore, cattle/livestock-administered endectocides seem a promising strategy that could be added to the current vector control strategies to control malaria in this region [33–35].
Endectocides, such as ivermectin and fipronil, are antiparasitic drugs that are active against both ecto- and endoparasites in humans and animals [36, 37]. Several studies have investigated the effect of endectocides against various malaria vectors such as An. arabiensis, An. coluzzii and An. gambiae in livestock, cattle in particular and show significant decreases in survival and fecundity [33–35]. The different routes of endectocides administration (injection, topical and oral) yield different degrees of effectivity and this must be considered before the strategy can be implemented . Subcutaneous injections, which is the most expensive option, is more effective than topical and oral administrations [33–35]. Although the use of cattle/livestock-administered endectocides in the Vhembe District could be beneficial in malaria control programs, it is unclear how such a strategy would be perceived by the local communities. Before the implementation of any public health strategy, it is important to consider the community perception, attitude and knowledge towards such a strategy as acceptance can have significant impacts in its effectiveness . For instance, in the Ebola outbreak that occurred in the West Africa in 2014, the local community played a key role in reducing the transmission, implementing community-based interventions including reducing body to body contact, wearing of protective gear and avoidance of crowding [39–42]. Another example of how the community’s acceptance is linked with the success of a health control strategy would be the patient separation from families and communities that was implemented to control the Marburg filovirus haemorrhagic fever outbreak that occurred in Angola in 2005 [43, 44].
The willingness of local farmers to enrol their livestock in an endectocide administration malaria control scheme would be similarly crucial for any planned intervention using endectocides. As chemical intervention strategies also come at a cost, effective interventions need to consider a number of factors for targeted applications. These include not only treating a sufficient number of livestock  but also preferentially treating those which are closer to human habitation and are thus, most likely to attract blood-seeking mosquitoes that may then feed on human hosts . Consequently, livestock in close proximity of the houses and kraals (animal pens) should preferentially be targeted for interventions. Some vector control strategies require behavioural changes and may need to be maintained over time in order for them to be cost-effective, thus reinforcing the need for effective and sustained community engagement . In the past, community livestock dipping programs in South Africa used to be popular and the costs were covered by the government . However, due to lack of resources and funds, such programs were abandoned in most areas and livestock owners became responsible for treating their livestock for diseases and parasites [47–48]. The use of inexpensive endectocides therefore becomes critical, if such costs were to be paid by local rural poor livestock owners.
The aim of this study was to assess the social acceptance and practicality of potential future livestock endectocide administration as an additional tool for malaria control in the malaria endemic villages of Vhembe District. Our approach to assess the acceptability and feasibility of this strategy included capturing (1) possible determinants such as the type and size of livestock, (2) the relative proximity of houses and kraals (animal enclosures), (3) contributions of previous malaria experience to the communities attitudes towards the proposed strategy and (4) the nature and extent of already used chemicals to treat livestock.