Moreover, the African continent is also affected by a number of vector-borne zoonotic infections caused either by viruses , Rift Valley Fever and Yellow Fever or by bacteria , which require parasitological and entomological expertise to be effectively addressed, due to their vectoral components . Indeed, recognising the parasitological/entomological constituents in the epidemiology of these infections is essential as it helps identifying potential arthropod or vertebrate reservoirs, thus ultimately preventing and controlling the diseases in humans and animals. In Uganda, for example, when it was first encountered, in 2013, CCHF was initially feared to be the more deadly Ebola , which has occasionally crossed the country’s border with the Democratic Republic of the Congo . Ever since, CCHF has occurred in the country in the form of outbreaks within or in the proximity of the “cattle corridor”, a region spanning northeastern, central and southwestern districts, known indeed for the density of its cattle herds . With most cases being associated with exposure to bites of ticks who have fed on viraemic cattle or ruminant hosts , the effective control of this infection could be achieved through the rollout of strategic targeted tick control programmes and the sensitisation of the general public and farming communities on the epidemiology of CCHF.
Considering that the same cattle corridor witnesses sporadic cases of mosquito-borne RVF , whose reservoir is also represented by ruminants , One Health efforts in this area should opt for the use of “arthropocidal” molecules, halting both ticks and mosquitoes, rather than merely “acaricidal” products or “insecticidal” ones .Moreover, the role of “companion” animals or non-livestock species, such as dogs and cats, is also critical for certain parasitic zoonoses in Africa. In addition to their involvement in a number of NTDs , these species are also implicated in the epidemiology of several zoonotic geohelminths such as Toxocara spp., Ancylostoma spp. and Strongyloides stercoralis, and cestodes , entailing direct or indirect transmission through an intermediate host . The frequent freeroaming behaviour of dogs and cats, typically in rural milieus across Africa , coupled with the usually poor hygiene and water sanitation of such settings, can particularly favour the spread of these parasitoses and enhance exposure risks in humans and other animal species. In addition, with the size of middle class rising in the continent , ownership of dogs and cats as “pets” may potentially increase in urban areas in the next decades, highlighting the importance of parasite control also in urban and peri-urban sites, where encounters between “owned” and “free-roaming” animals, and their excretions, may occur.
Furthermore, the contribution of wildlife needs also to be considered, either as definitive or intermediate hosts or even reservoirs of zoonotic parasites . Therefore, in order to be fully and durably effective, One Health initiatives tackling parasitic conditions should aim to tackle all final, intermediate, potentially vector and even paratenic or transport hosts involved in life cycles of target aetiological agents. Overlooking even a single host species, wildlife included, can indeed cause the reappearance or impede the elimination tout court of cases of infection or disease in certain other hosts, despite generous control efforts being addressed towards them.Should the One Health approach be envisaged only in the case of zoonotic parasitic or arthropod-borne infections that are shared between humans and animals? This concept paper advocates for a more comprehensive assessment of parasites and vectors in this paradigm. The health of livestock in Africa is indeed undermined by several parasites or arthropods that, although not zoonotic per se, cause major chronic deterioration and productivity losses, being responsible for low body condition scoring, poor protein conversion and, overall, scarce production .
In the case of cattle, for instance, gastrointestinal nematodes, ticks and tick-borne infections and animal African trypanosomiasis are the most important examples to be incriminated in these regards . The productivity losses that they entail are therefore inextricably connected with the continent’s food insecurity, especially considering that the largest bulk of Africa’s food production is used for local consumption . With food insecurity being recognised as a global health challenge , all its major causes in the animal sources should be thoroughly investigated and tackled under the One Health lens. This applies also to animals’ and livestock parasitic infections, given the burden they pose, ultimately, to human sustainment and nutrition. As the OIE puts it, “pathogens of animal origin that are not transmissible to humans, but which have a severe impact on the production of animal protein, should not be neglected either, particularly in developing countries. In fact, they can lead to production losses and a reduction in the available food supply, leading to serious public health problems caused by food shortages and protein deficiencies” .