Distribution of rodenticide resistance and zoonotic pathogens in Norway rats in Lower Saxony and Hamburg, Germany.
BACKGROUND
Genetically based resistance to anticoagulants has led to increasing difficulties in the control of rodents over recent decades. The possible impact of rodenticide-resistant rats on the infection risk of humans and livestock by zoonotic pathogens is generally unknown. Hence, in a monitoring programme in the German federal states of Lower Saxony and Hamburg, more than 500 Norway rats were analysed for both Tyr139Cys polymorphisms within the VKORC1 gene and zoonotic agents.


RESULTS
Evidence of resistance was almost completely restricted to the known resistance area in southern Lower Saxony. Homozygous mutations were only found in urban areas sampled owing to the occurrence of rat control problems and were missing in bycatches of rats by muskrat trappers in rural areas. In more than 25% of the rats, zoonotic bacteria (Leptospira, Salmonella, Yersinia and Coxiella) were detected. There was no obvious correlation between the occurrence of rats carrying zoonotic pathogens and anticoagulant resistance.


CONCLUSIONS
Zoonotic agents and genetically based resistance conferred by the Tyr139Cys polymorphism are both unevenly distributed in Lower Saxony. The study provides the basis for further studies focusing on districts with high levels of pathogens and resistance to assess the potential health risk of their combined occurrence.
Lower Saxony State Office for Consumer Protection and Food Safety (LAVES), Food and Veterinary Institute Braunschweig/Hannover, Hannover, Germany.
Martin
M
Runge
Michael
M
von Keyserlingk
Silke
S
Braune
Detlef
D
Becker
Anita
A
Plenge-Bönig
Jona F
JF
Freise
Hans-Joachim
HJ
Pelz
Alexandra
A
Esther
D000818:Animals; D001419:Bacteria / Q000302:isolation & purification; D004351:Drug Resistance; D005858:Germany; D006899:Mixed Function Oxygenases / Q000235:genetics / Q000378:metabolism; D020125:Mutation, Missense; D020641:Polymorphism, Single Nucleotide; D051381:Rats / Q000235:genetics / Q000382:microbiology / Q000502:physiology*; D012375:Rodent Control; D012378:Rodenticides / Q000494:pharmacology*; D064417:Vitamin K Epoxide Reductases; D015047:Zoonoses / Q000382:microbiology* / Q000635:transmission
D012378:Rodenticides; D006899:Mixed Function Oxygenases; C578523:VKORC1 protein, human; D064417:Vitamin K Epoxide Reductases