Molecular detection of vector-borne pathogens from mosquitoes collected in two zoological gardens in Germany

Eva C Heym,Mandy Schäfer,Helge Kampen,Doreen Werner,Oliver Krone

doi:10.1007/s00436-019-06327-5

Abstract

In Germany, knowledge of disease agents transmitted by arthropods in zoological gardens is scarce. In the framework of ecological studies, mosquitoes were therefore collected in German zoological gardens and examined for mosquito-borne pathogen DNA and RNA. In total, 3840 mosquitoes were screened for filarial nematodes and three groups of viruses (orthobunyaviruses, flaviviruses, alphaviruses) while 405 mosquitoes were tested for avian malaria parasites. In addition to the filarial nematode species Dirofilaria repens (n = 1) and Setaria tundra (n = 8), Sindbis virus (n = 1) and the haemosporidian genera Haemoproteus (n = 8), Leucocytozoon (n = 10) and Plasmodium (n = 1) were demonstrated. Identified pathogens have the potential to cause disease in zoo and wild animals, but some of them also in humans. Positive mosquitoes were collected most often in July, indicating the highest infection risk during this month. Most of the pathogens were found in mosquito specimens of the Culex pipiens complex, suggesting that its members possibly act as the most important vectors in the surveyed zoos, although the mere demonstration of pathogen DNA/RNA in a homogenised complete mosquito is not finally indicative for a vector role. Outcomes of the study are not only significant for arthropod management in zoological gardens, but also for the general understanding of the occurrence and spread of mosquito-borne disease agents.

Highlights

Through globalisation, both invasive mosquito species and mosquito-borne pathogens can be introduced into temperate climate zones such as central Europe
From the Zoological Garden Eberswalde, 2407 mosquito females belonging to 20 taxa were screened for filarial nematodes and viruses
While D. repens has not been documented from a zoo animal yet, the parasite had already been detected in Germany in 2011 and 2012 in mosquitoes caught only 30 km away from the Zoological Garden Eberswalde (Czajka et al 2014), and, apparently, autochthonous infections had been diagnosed in dogs in the same federal state of Brandenburg (Sassnau et al 2009)

Summary

Introduction

Both invasive mosquito species and mosquito-borne pathogens can be introduced into temperate climate zones such as central Europe. Climate change might facilitate survival of the mosquitoes in the newly invaded regions and lead to conditions allowing pathogen development or increasing the efficiency of pathogen replication in vector-competent mosquito species (Weissenböck et al 2010). As both globalisation and climate change significantly increase the risk of mosquito-borne disease outbreaks Monitoring mosquito-borne pathogens faces difficulties since not all potential vectors are known, and most infections, of animals, remain undetected. Zoological gardens offer ideal living conditions for mosquitoes through numerous breeding and resting sites and provision of a high diversity of vertebrate species for blood feeding (Tuten 2011)

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