Trends and Opportunities in Tick-Borne Disease Geography

Abstract

Tick-borne diseases are a growing problem in many parts of the world, and their surveillance and control touch on challenging issues in medical entomology, agricultural health, veterinary medicine, and biosecurity. Spatial approaches can be used to synthesize the data generated by integrative One Health surveillance systems, and help stakeholders, managers, and medical geographers understand the current and future distribution of risk. Here, we performed a systematic review of over 8,000 studies and identified a total of 303 scientific publications that map tick-borne diseases using data on vectors, pathogens, and hosts (including wildlife, livestock, and human cases). We find that the field is growing rapidly, with the major Ixodes-borne diseases (Lyme disease and tick-borne encephalitis in particular) giving way to monitoring efforts that encompass a broader range of threats. We find a tremendous diversity of methods used to map tick-borne disease, but also find major gaps: data on the enzootic cycle of tick-borne pathogens is severely underutilized, and mapping efforts are mostly limited to Europe and North America. We suggest that future work can readily apply available methods to track the distributions of tick-borne diseases in Africa and Asia, following a One Health approach that combines medical and veterinary surveillance for maximum impact.

Keywords: geospatial; maps; prevalence species distribution modeling; tick-borne diseases.

Fig. 1.

PRISMA flow diagram outlining the literature search and screening process.

Fig. 2.

The cumulative number of studies that collected data about a given genus of tick vector (A) or tick-borne disease (B).

Fig. 3.

The cumulative number of studies using any of eight given methodologies.

Fig. 4.

The proportion of studies using different data sources to generate maps of tick-borne disease distribution, transmission, or risk. Many studies use (A) pathogen data directly (75%) and (B) human case data (40%), while fewer use (C) livestock infection data (12%) or (D) wildlife infection data (10%).

Fig. 5.

Proportion of studies with data on different wildlife (A) and livestock species (B).

Fig. 6.

Number of studies describing the geography of tick-borne disease by country, excluding a handful of explicitly continental studies (most notably 20 in Europe, as well as four in Africa, two in the eastern Mediterranean, one in Asia, and four global mapping studies).