The diversity and impact of hookworm infections in wildlife

Abstract

Hookworms are blood-feeding nematodes that parasitize the alimentary system of mammals. Despite their high pathogenic potential, little is known about their diversity and impact in wildlife populations. We conducted a systematic review of the literature on hookworm infections of wildlife and analyzed 218 studies qualitative and quantitatively. At least 68 hookworm species have been described in 9 orders, 24 families, and 111 species of wild mammals. Black bears, red foxes, and bobcats harbored the highest diversity of hookworm species and Ancylostoma pluridentatum, A. tubaeforme, Uncinaria stenocephala and Necator americanus were the hookworm species with the highest host diversity index. Hookworm infections cause anemia, retarded growth, tissue damage, inflammation and significant mortality in several wildlife species. Anemia has been documented more commonly in canids, felids and otariids, and retarded growth only in otariids. Population- level mortality has been documented through controlled studies only in canines and eared seals although sporadic mortality has been noticed in felines, bears and elephants. The main driver of hookworm pathogenic effects was the hookworm biomass in a population, measured as prevalence, mean burden and hookworm size (length). Many studies recorded significant differences in prevalence and mean intensity among regions related to contrasts in local humidity, temperature, and host population density. These findings, plus the ability of hookworms to perpetuate in different host species, create a dynamic scenario where changes in climate and the domestic animal-human-wildlife interface will potentially affect the dynamics and consequences of hookworm infections in wildlife.

Keywords: Ancylostoma; Epidemiology; Hookworm; Pathology; Uncinaria; Wildlife.

Graphical abstract

Fig. 1

Percentage of studies describing hookworm infections in wildlife hosts divided by continent (a) and the main methodology used to collect the data (b).

Fig. 2

Hookworm diversity index penalized by the citation principal component (citation-PC) of the host species (a) and the number of sampled animals of each host species (b). Bar colors indicate represented mammalian orders. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

Fig. 3

Host species diversity index for represented hookworm species, penalized by number of animals sampled (a) and the number of animal species sampled in each study (b).