One hundred years of zoonoses research in the Horn of Africa: A scoping review

Abstract

Background: One Health is particularly relevant to the Horn of Africa where many people's livelihoods are highly dependent on livestock and their shared environment. In this context, zoonoses may have a dramatic impact on both human and animal health, but also on country economies. This scoping review aimed to characterise and evaluate the nature of zoonotic disease research in the Horn region. Specifically, it addressed the following questions: (i) what specific zoonotic diseases have been prioritised for research, (ii) what data have been reported (human, animal or environment), (iii) what methods have been applied, and (iv) who has been doing the research?

Methodology/principal findings: We used keyword combinations to search online databases for peer-reviewed papers and theses. Screening and data extraction (disease, country, domain and method) was performed using DistillerSR. A total of 2055 studies focusing on seven countries and over 60 zoonoses were included. Brucellosis attracted the highest attention in terms of research while anthrax, Q fever and leptospirosis have been comparatively under-studied. Research efforts did not always align with zoonoses priorities identified at national levels. Despite zoonoses being a clear target for 'One Health' research, a very limited proportion of studies report data on the three domains of human, animal and environment. Descriptive and observational epidemiological studies were dominant and only a low proportion of publications were multidisciplinary. Finally, we found that a minority of international collaborations were between Global South countries with a high proportion of authors having affiliations from outside the Horn of Africa.

Conclusions/significance: There is a growing interest in zoonoses research in the Horn of Africa. Recommendations arising from this scoping review include: (i) ensuring zoonoses research aligns with national and global research agendas; (ii) encouraging researchers to adopt a holistic, transdisciplinary One Health approach following high quality reporting standards (COHERE, PRISMA, etc.); and (iii) empowering local researchers supported by regional and international partnerships to engage in zoonoses research.

Fig 1. Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flow diagram detailing number of papers on zoonoses in the Horn of Africa retrieved and selected for data extraction.

Note that papers were excluded if they did not meet any one of the two inclusion criteria, hence numbers stated for each criterion do not add up to the total number of records excluded.

Fig 2. Number of publications on zoonoses in the Horn of Africa, by country of focus and year.

The bars in red represent the year the national zoonoses prioritisation workshops were conducted for the concerned countries.

Fig 3. Radar charts showing number of publications on zoonoses in the Horn of Africa, by country of focus and disease (n = 2055).

Numbers in parentheses (n) identify the rank of each zoonosis in national prioritisation workshops (when available). RVF = Rift Valley fever. Note: only those fourteen diseases included in the specific disease search are shown; for full listing of “Other zoonoses” see S5 Table.

Fig 4. Venn diagrams showing the data reported in 2055 publications on zoonoses in the Horn of Africa, by disease and ‘One Health domain’.

Note: blue is for human, red for animal and green for environment domain.

Fig 5. International authorship network associated with publications on zoonoses in the Horn of Africa, by country of focus: (A) all papers, (B) Kenya, (C) Ethiopia, (D) Uganda.

In each panel, the regional collaboration within the Horn of Africa is shown as an inset. Node size and link thickness correspond to the number of unique author-affiliations and paper-collaborations in Table 4, respectively. As we aggregated papers from Sudan/South Sudan, this node is shown at the frontier between the two countries. Intra-country collaborations are not shown. The scale is the same across all maps. The base layer of the map is accessible here: https://datacatalog.worldbank.org/dataset/world-bank-official-boundaries. See S1 File for complete list of nodes and links shown in this figure.