Chapter 14

Chapter 14 BIOLOGY AND CONTROL OF RODENTS

DR. D. T. CAPPUCCI, JR.

14.1 Objectives:

To review

1) the role of rodents in zoonotic disease transmission and

2) to review the biology and control of rodent pests.

14.2 Introduction

A. Rodents cause millions of dollars damage, worldwide, through consumption and contamination of crops and other foods intended for humans and animals. They also cause destruction to merchandise, buildings, and various other items. From a public health standpoint, rodents inflict large numbers of bites and transmit numerous diseases to humans and other animals.
B. Role of rodents in history - Black Death in the Middle Ages
C. Role of rodents in religion - mouse worshiping in Orient
D. Impact of rodents in international commerce and trade
E. International quarantine measures and rodents
F. Impact of rodent pests on politics and contemporary issues
G. Role and impact of rodents in research, experimentation, and testing

14.3 Rodent Biology

A. Rat species

1. Norway rat (Rattus norvegicus)
2. Roof rat (Rattus rattus)
3. Others

B. Mouse species -

1. House mouse (Mus musculus)
2. Others

C. Field identification of domestic rodents (Refer to Figure 1)

D. Habits of Rats and Mice

1. Nesting places
2. Senses
3. Good jumpers, climbers, swimmers, gnawers
4. Other behavioral features - rats range up to 100 feet from their nests; mice range up to 30 feet from their nests

14.4 Rodents as Pests

14.5 Rodents as Disease Carriers

A. Bacterial, viral, mycotic, parasitic, and rickettsial diseases:

1. Plague or Black Death
2. Murine typhus
3. Infectious jaundice (leptospirosis)
4. Trichinosis
5. Rat bite fever
6. Typhoid, dysentery (salmonellosis)
7. Rabies (very rare in rodents)
8. Toxoplasmosis
9. Tularemia
10. Lymphocytic choriomeningitis
11. Colorado tick fever
12. Lassa fever
13. Helminths (tapeworms, nematodes, and flukes)
14. Others

14.6 Rat and Mice Control

A. Signs of infestation (harborages, and so forth)

1. Rodent survey techniques (observational assessments and descriptive epidemiological studies)
2. gnawing, burrows, droppings, runways, foot and tail marks, other

B. Rat proofing

A form of rodent control using ratproof materials and construction thereof, to reduce entry into facilities or premises

C. Mouse proofing

Similar to rat proofing

D. Use of poisons

Anticoagulant rodenticides, ANTU, bromethalin, phosphorus, red squill, 1080, 1081, thallium sulfate, zinc phosphide, aluminum phosphide, cholecalciferol, and others.

1. Pesticide rules of safety - alternative options to the use of pesticides are mandatory relative to animal/public health and safety. Poison control centers have reported numerous cases of humans and animals accidentally or deliberately poisoned with rodenticides.
2. Environmental and wildlife concerns - The Environmental Protection Agency and Department of Interior as well as Congress and the Office of the President have been involved with environmental and wildlife issues dealing with the abuse and misuse of rodenticides.

E. Use of traps

Most successful when used in combination with rodent poisoning.
Rodents become weary and do not use traps that have long standing bait.
The search continues for building a better rat/mouse trap.

F. Other control measures

Environmental sanitation is mandatory for controlling rodents.
Rat/mouse stoppage is a form of proofing by sealing all holes, cracks, and crevices of buildings that can be used as entries/exits by rodents.
Natural enemies of rodents such as mongooses, snakes, and rat terriers have been used by some individuals as a control measure.

14.7Significance of Wild Rodent Pests in Laboratory Animal Research Facilities

VIII. References

Beaver, P. C. and Jung, R. C., Animal Agents and Vectors of Human Disease, 5th ed. Lea and Febiger, Philadelphia, 1985.
Bell, J. C., Palmer, S. R. and Payne, J. M., The Zoonoses. Infections Transmitted from Animals to Man. Edward Arnold, London, 1988.

Ehlers, V. M. and Steel, E. W. Municipal and Rural Sanitation, 6th ed.. McGraw-Hill Book Company, New York, 1965.

Harkness, J. E. and Wagner, J. E., The Biology and Medicine of Rabbits and Rodents, 3rd ed. Lea and Febiger, Philadelphia, 1989.

Schwabe, C. W. Veterinary Medicine and Human Health, 3rd ed., Williams & Wilkins, Baltimore, 1984

Weber, W. J., Diseases Transmitted by Rats and Mice. Thomson

publications,Fresn.

IX. Questions

1. Compare and contrast the field identification of rats and mice (based on Figure 1 handout).
2. Discuss the uses of poisons and traps for rodent pest control.

3. Name at least 6 diseases associated with rats and mice.

4. Discuss rodent survey techniques used in municipal and rural sanitation.

5. Discuss rat proofing and rat stoppage.

6. Name at least 6 common rat harborages and what can be done about them.

7. What is the vector of plague?

8. What is the vector of murine typhus?

9. True or False. Epidemic typhus is also called fleaborne typhus.

10. True or False. Endemic typhus is also called fleaborne typhus.

11. Discuss the ecological differences between sylvatic and urban plague.

12. True or False. Wild rodent pests pose no threat to experimental animals maintained under laboratory conditions. Explain.

13. Relative to getting rid of rat harborages, what would you do with the following: (thought questions)

a. Abandoned cars
b. Abandoned and dilapidated buildings

c. Abandoned appliances (stoves, refrigerators, etc.)

d. Large rubbish or garbage piles

e. Tall grass, weeds, and other vegetation

f. Stacks of lumber

g. Abandoned compost piles