Diabetes and myocarditis in voles and lemmings at cyclic peak densities—induced by Ljungan virus?

Abstract

Although it is well-documented from theoretical studies that pathogens have the capacity to generate cycles, the occurrence and role of pathogens and disease have been poorly empirically studied in cyclic voles and lemmings. In screening for the occurrence of disease in cyclic vole and lemming populations, we found that a high proportion of live-trapped Clethrionomys glareolus, C. rufocanus, Microtus agrestis and Lemmus lemmus at high collective peak density, shortly before the decline, suffered from diabetes or myocarditis in northern Scandinavia. A high frequency of animals had abnormal blood glucose (BG) levels at the time of trapping (5-33%). In contrast, C. rufocanus individuals tested at a much lower overall density, and at an earlier stage relative to the decline in the following cycle, showed normal BG concentrations. However, a high proportion (43%) of a sample of these individuals kept in captivity developed clinical diabetes within five weeks, as determined by BG levels and a glucose tolerance test performed at that later time. A new picornavirus isolated from the rodents, Ljungan virus (LV), was assumed to cause the diseases, as LV-induced diabetes and myocarditis, as well as encephalitis and fetal deaths, were observed in laboratory mice. We hypothesize that LV infection significantly affects morbidity and mortality rates in the wild, either directly or indirectly, by predisposing the rodents to predation, and is at least involved in causing the regular, rapid population declines of these cyclic voles and lemmings. Increased stress at peak densities is thought to be an important trigger for the development of disease, as the occurrence of disease in laboratory mice has been found to be triggered by introducing stress to LV-infected animals.

Genetic Testing of Newborns for Type 1 Diabetes Susceptibility – The MIDIA Study

“…Our most recent case-control study shows no difference in positivity for human parechovirus infections in stool samples (Tapia et al, 2010). Ljungan virus has earlier been shown to cause diabetes-like condition in rodents (Niklasson et al, 2006), but was not identified in samples from children in our studies (Tapia et al, 2008, Tapia et al, 2010. HPeV1 has been reported to show no association with T1D (Tauriainen et al, 2007), but there is no data on the other types of HPeVs.…”

Lymphocytic choriomeningitis, Ljungan and orthopoxvirus seroconversions in patients hospitalized due to acute Puumala hantavirus infection

“…LV has been associated with several human diseases [26,[28][29][30][31], and causes symptoms in laboratory mice [28], but LV has yet to be isolated from humans or proven a causative agent of disease. High seroprevalence (36%, 38%) to LV has recently been detected in humans in Finland [15], indicating a fairly high exposure to LV and/or to an antigenically-related virus in early childhood.…”

Physicochemical Properties of the Ljungan Virus Prototype Virion in Different Environments: Inactivated by Heat but Resistant to Acidic pH, Detergents and Non‐Physiological Environments Such as Virkon®‐Containing Solutions

“…Ljungan virus (LV) is a picornavirus recently isolated from different vole species (Clethrionomys glareolus, C. gapperi, Microtus montanus, M. pennsylvanicus) in Sweden and on the American continent (5,16,18,19,22,26,43). LV cause diabetes, myocarditis and other diseases in rodents, and LV has also been suggested to be involved in human diseases (25)(26)(27)(28)(29)(30)34). LV was recently associated with intrauterine fetal deaths in humans (31).…”