Urban Biomes – An Ecological Niche For Potential Hantavirus Vectors (cont'd).
by Stewart Mitchell, PhD

The deer mouse has some notoriety due to its coloration, having been represented on a United States postage stamp. The deer mouse has a beneficial side in biological pest management by consuming invasive species like the gypsy moth Lymantria dispar. In addition, germaplasm and detritus are randomized through the innate and instinctual feral activities of this rodent species.
The morphology of the deer mouse is consistent with the order Rodentia (meaning "to gnaw"). This species has pronounced corneal surface area translating an obscure – monochromatic and primarily unicameral field of vision, which is adapted to nocturnal activity. Pronounced auricles allow acute sound sensitivity into the ultrasonic range (+/- 90 KHz). Olfactory structures provide acute sensory interpretation. Taste pathways allow taste sensitivity to < 250 ppb. The pelage is dorsally dark in shades of brown, ventrally white, and the tail appendage is bi-colored but somewhat denuded. Tarsal forms are white and well adapted to thigmotaxic process. Innervated hairs (vibrissae) flanking the olfactory structures and body surface area enhance the thigmophilic tendencies of the deer mouse. The body is approximately 6 inches (155 mm) in length – weighing about 1 ounce (28.35 gm), including the posterior appendage. The deer mouse has opposing incisors that grow constantly (0.4 mm per day). The anterior sides of the incisors are enameled, while the posterior side is dentinized. Considerable musculature in the jaws allows invasive pursuit of natural and synthetic strata. Deer mice spend 2 to 3% of their time in gnawing behavior, preferring perpendicular surface orientations as opposed to circular. A diastema process located postincisor and premolar allows the "cheek" tissue of the mouth to plug this space, disallowing ingestion of non-edible matter resulting from gnawing.

Deer mice reach sexual maturity in approximately eight weeks. A litter of pups is generally three to six individuals with as many as four litters per year. Deer mice have a life span between two months and two years depending on environmental stresses as defined by their tropic level. Their preferred diet is herbivorous, but can readily transition to omnivorous. Nesting sites are preferred in spherical cell elements regardless of natural or synthetic derivation. Innate climbing ability provides deer mice with a spacial range of up to 100 feet (30.33 m).

Population management of the deer mouse, pursuant to structure, can be 90% effective by employing precise exclusion practices. Proper construction tolerances and avoidance of delayed maintenance issues will diminish conducive conditions that tend to favor rodent invasion. Flush entrances, windows, utility lines, vents, and other services will exclude deer mouse egress. Egress peaks when seasonal transitions expedite acute temperature drops in-turn effecting available harborage and nutritional assets. Proper organizational storage practices relative to interior and exterior structural areas, reduces the exploitation of resources by deer mice and other rodents. The aforementioned practices eliminate the use of pesticides and their potential biomagnifications.

Sin Nombre virus infection results from an incision wound initiated by an infected rodent, as well as exposure to urine, scats, or saliva via tactile mobility, ingestion, or aerosolization. The hantavirus resulting in HPS cannot be transmitted from one individual to another. In addition, Sin Nombre virus is not transmitted by plasma seeking arthropods and is limited to two factorial transmissions – zoonotically.

In occupational or remedial practice, it is advised to utilize proper personal protective equipment (PPE) within confined spaces. Wetting agents can be employed to disinfect areas prior to entering. Appropriately labeled viricides are available to neutralize Sin Nombre and other hantaviruses.

The global dominance of human beings, as a species, continues to redefine itself in the realm of "progress." We must be cognizant of the first law of human ecology. "We can never do merely one thing. Any intrusion into nature has numerous effects, many of which are unpredictable." Anthropogenically, we are an invasive species. What we do now, will dictate our future as a species. Sustainable development mandates environmental protocols. As a global community, we are all ultimately accountable for the health of our environment and the ecology of life. Whether urban or natural biomes, all ecological niches require respect and preservation.

Acknowledgements:

Chin, J. – 2000. Communicable Disease. American Public Health Association. Washington, DC ISBN: 0-87553-242-X soft cover.

Corrigan, R.M. – 2001. Rodent Control. GIE Media. Cleveland, OH. ISBN: 1-883751-16-0.