illness( 30 cases, of which 20 died) in 1993 in the Four Corners and Yosemite. This one was tracked to the deer mouse( disseminated by aerosolized urine, feces or saliva of the infected mouse). Thankfully, this virus does not spread from human to human; you may recall that this strain of virus gained national attention when it was determined that Betsy Arakawa, wife of the famous movie star Gene Hackman, may have died from hantavirus pulmonary syndrome( HPS).
There have been minor instances in Long Island, New York( New York orthohanta virus) carried by white-footed mouse( 1993-1995), with a Monongahela variant in Pennsylvania and a Bayou hantavirus in Louisiana. The hantavirus Andes strain linked to pygmy rice rats, native to Argentina and Chile, was the one involved in the recent outbreak in the cruise ship. Fortunately, that strain is not found in North America. Apparently, the Andes strain is the only one that is known to spread from human to human, well-documented in Argentina in 1996, where one infected person gave it to many others while attending a birthday party. 2 The recent outbreak in the cruise ship apparently came through a couple who boarded the ship after hiking along rural areas of South America carrying the Andes strain, which spread from one person to another in the ship via respiratory droplets or direct exposure to bodily fluids.
Now for the“ good” role: You may be wondering what good can come out of the rodents? Let me start with my personal experience. When I joined as a fellow in EMG at Vanderbilt University School of Medicine in the‘ 70s, I was fascinated with the so-called“ fainting goats,” a colony of which was kept by Dr. Virgil LeQuire, Professor of Cell Biology and Pathology at Vandy. By then it was recognized that these goats do not actually faint: they fall due to persistent contraction of muscles from the phenomenon of myotonia. The condition resembles myotonia congenita, a hereditary disease in humans, described by Julius Thomsen in 1876. Myotonia is easily diagnosed by needle electromyography as the auditory signature of the electrical discharges produce the classic“ dive bomber” sound.
I was keen to study the mechanism of myotonia but needed an in vitro model rather than the myotonic goat. Among the various options, rat diaphragm was a great model for in vitro study, using a chemical to induce myotonia. 3 Since then, I have routinely used rodents to study many different conditions ranging from nerve injury to epilepsy. I regarded rodents as the“ omnipresent after-hour patients” readily available for research even in the evenings and weekends.
Rats and mice share certain anatomical, physiological and genetic similarities with humans, so much so that they have become the bedrock of medical research. Scientists opine that the mouse genome is homologous to human genome in many ways, and their short gestation period and lifespan are additional advantages in using them as experimental models. The mouse genome was sequenced in 2002 and the rat genome in 2004. A breakthrough occurred when techniques to produce“ knock out” models( preventing specific genes from expressing themselves), became available thanks to Mario Capecchi, Martin Evans and Oliver Smithies( Nobel prize winners for Physiology or Medicine in 2007).
One of the first genes they targeted was the one known to mutate in patients with cystic fibrosis, called the CFTR for“ cystic fibrosis transmembrane conductance regulator.” By knocking out this CFTR gene, many of the features of cystic fibrosis could be reproduced in the mice. Knocking out the p53 tumor suppressor gene can produce a model resembling Li Fraumeni syndrome( characterized by occurrence of multiple cancers), leading to impressive advances in oncological research. There has been phenomenal progress over the past several years leading to the creation of knockout mice for close to 10,000 genes, and soon there will be knockout phenotype for every mouse gene. Thanks to CRISPR, the gene editing technology( discovered by Jennifer Doudna and Emmanuelle Charpentier, who were awarded the Nobel Prize in Chemistry in 2020), the process of knocking out genes has become much quicker. One can even make multiple genes non-functional simultaneously. CRISPR also allows“ knock-in” models facilitating the introduction of new genes and the production of“ humanized mice” replacing mouse genes with human genes. Apart from the opportunity to study the function of various genes, these techniques allow effective development of disease models and drug development.
In 2007, the Nobel assembly predicted that“ Gene targeting in mice has pervaded all fields of biomedicine. Its impact on the understanding of gene function and its benefits to mankind will continue to increase over many years to come.” This has indeed come true. It is also obvious that rodents have attained an unprecedented and enviable stature in biomedical science. There is even a journal RATS with the mission of“ Advancing education and training in the fields science, medicine, veterinary medicine, technology and care of laboratory animals.” I am more than convinced that as far as rodents go,“ The good far outweighs the bad and the ugly.” Let me conclude with an apt quote by Douglas Adams in his fabulous book, The Hitchhiker’ s Guide to the Galaxy.
“ These creatures you call mice, you see, they are not quite as they appear. They are merely the protrusion into our dimension of vastly hyperintelligent pandimensional beings.”
References
1
Rabiee MH et al. Rodent-borne diseases and their public health importance in Iran. PLoS Negl Trop Dis 2018; 12( 4): e0006256.
2
Coelho R et al. Virological characterization of a new isolated strain of Andes virus involved in the recent person-to-person transmission outbreak reported in Argentina. PLoS Negl Trop Dis. 2025; 19( 6): e0013205.
3
Iyer V. et al. Ionic conductance in experimentally induced myotonia. J of Neurological Sci. 1981; 49( 2): 159-164
Dr. Iyer practices at the Neurodiagnostic Center of Louisville and is a retired professor of neurology at the University of Louisville School of Medicine.
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