Environmental Engineering Reference
In-Depth Information
The rodentborne diseases include rat-bite fever, Haverhill fever, leptospirosis,
choriomeningitis, salmonellosis, tularemia, possibly amebiasis or amebic
dysentery, rabies, trichinosis (indirectly), and tapeworm. Epidemic typhus,
endemic or murine typhus, Rocky Mountain spotted fever, tsutsugamushi
disease, hantavirus,
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and others are sometimes included in this group. Although
rodents are reservoirs of these diseases (typhus, spotted fever, etc.), the diseases
themselves are actually spread by the bite of an infected flea, tick, or mite or
the blood or feces of an infected flea or tick on broken skin, as previously
discussed. Rats are also carriers of
S. aureus, E. coli, Y. enterocolitica
,and
Yersinia pseudotuberculosis
, as well as leptospirae and other pathogens.
Sodoku and Haverhill fevers are two types of rat-bite fever. The incubation
period for both is 3 to 10 days. Contaminated milk has also been involved as
the cause of Haverhill fever. The importance of controlling and destroying rats,
particularly around dwellings and barns, is again emphasized.
The causative organism of leptospirosis, also known as Weil's disease, spiro-
chetosis icterohemorrhagic, leptospiral jaundice, spirochaetal jaundice, hemor-
rhagic jaundice, canicola fever, mud fever, and swineherd's disease, is transmitted
by the urine of infected rodents, cattle, dogs, swine, and wild animals. Direct
contact or the consumption of contaminated food or water or direct contact with
waters containing the leptospira may cause the infection after 4 to 19 days.
Dogs are carriers of many microorganisms and parasites that are discharged in
the feces and urine and that may be transmitted to humans, particularly children.
These include
G. lamblia
and
T. canis
, an ascarid roundworm (the larval stage
in humans is called visceral larva migrans, a rare but serious disease if the larval
stage lodges in the brain, eyes, heart, or liver).
Toxocara cati
and
Ancylostoma
brazillense
are found in cats.
Ancylostoma caninum
is a canine hookworm that
may affect humans.
Dipylidium caninum
and
Taenia pisiformis
are two common
canine tapeworms;
Toxoplasma gondii
, a protozoa causing toxoplasmosis is also
carried by cats, goats, pigs, rats, pigeons, and humans. Salmonella and campy-
lobacter bacteria can also be transmitted to humans and from humans to dogs.
Dogs are the reservoir of many other diseases. Stray and pet dogs are carriers of
Brucella canis
; stray dogs have a higher rate of infection (9 percent as compared
to 1 percent for pet dogs).
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A significant number of dogs and cats excrete the
toxocara ova, and the hazard to human health is reported to be considerable.
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General control measures include proper disposal of dog feces; avoidance of
contact with the feces, such as in children's play areas; deworming of dogs; reg-
ulation of dogs in urban areas; and personal hygiene. In addition, there are the
hazards associated with fleas, ticks, and rabies as well as play areas and street
pollution from feces and urine. Pregnant women should exercise extreme sanitary
precautions and avoid any contact.
The virus causing lymphocytic choriomeningitis (LCM) is found in the mouth
and nasal secretions, urine, and feces of infected house mice, which, in turn, can
infect guinea pigs and hamsters. The virus is probably spread by contact, bedding,
or consumption of food contaminated by the discharges of an infected mouse.
The disease occurs after an incubation period of 8 to 21 days. Precautions include
