Seroepidemiological Studies of Crimean-Congo Hemorrhagic Fever Virus in Domestic and Wild Animals

Abstract

Crimean-Congo hemorrhagic fever (CCHF) is a widely distributed, tick-borne viral disease. Humans are the only species known to develop illness after CCHF virus (CCHFV) infection, characterized by a nonspecific febrile illness that can progress to severe, often fatal, hemorrhagic disease. A variety of animals may serve as asymptomatic reservoirs of CCHFV in an endemic cycle of transmission. Seroepidemiological studies have been instrumental in elucidating CCHFV reservoirs and in determining endemic foci of viral transmission. Herein, we review over 50 years of CCHFV seroepidemiological studies in domestic and wild animals. This review highlights the role of livestock in the maintenance and transmission of CCHFV, and provides a detailed summary of seroepidemiological studies of wild animal species, reflecting their relative roles in CCHFV ecology.

A chronological review of experimental infection studies of the role of wild animals and livestock in the maintenance and transmission of Crimean-Congo hemorrhagic fever virus

“…It is the second article in a series that aims to provide a definitive account of research on Crimean-Congo hemorrhagic fever (CCHF), which has not been thoroughly examined since the monumental monograph by the noted acarologist Harry Hoogstraal was published in 1979 (1). The first paper reviewed seroepidemiologic studies of the geographic distribution, host range, and frequency of CCHFV infection of wild and domestic animals (2). Additional articles in this series will review the role of ticks in the maintenance of CCHFV and its transmission to vertebrates including humans, and the attempts to replicate important features of CCHF through experimental infection of laboratory animals.…”

“…Of note, the studies detailed below are limited to small mammalian species, and although serological data do exist (as detailed in Spengler et al . [2]), to our knowledge, no experimental studies have been performed in larger wild mammalian species.…”

“…They can also expose humans to CCHFV directly through infected blood or crushing of engorged ticks on the animals during slaughtering (39–43). Seroepidemiological investigations have shown that a wide spectrum of domestic species is exposed to CCHFV (2), but experimental infection studies have been markedly more limited and have focused almost exclusively on assessment of viremia alone. Although small in number, experimental infections have been performed in several livestock species, including ruminants (cattle, sheep) and equids (horses, donkeys); these studies are summarized in Table 2.…”

“…The role of equids in maintenance and transmission of CCHFV is not well described, but serological data support natural exposure to virus (2). Experimental infection studies were performed in both horses and donkeys to investigate the possibility of producing antibodies for putative antibody-based human therapeutics.…”

“…Despite extensive investigations, the absence of serological evidence of CCHFV-specific antibodies in most avian species sampled suggests that most birds are predominantly refractory to CCHFV infection. However, resistance is not uniform, as there is serological evidence of exposure in some species (2). In the original outbreak in Crimea in 1944, Grobov collected immature H. marginatum ticks from wild birds and domestic fowl, considering birds as the putative reservoir of the then-unknown infectious agent (54).…”