ZOONOSES

 

Dr. Jacob Chacko, D.V.M., Public Health Veterinarian

U.S. Department of Agriculture.

 

 

A. Diseases that are transmitted between animals and humans.

      There are120 known Zoonoses agents according to CDC.

      Risk of contracting disease varies depending on the disease and

            Situation

B.   Focus on farming

            Working on farms increase risks --- why?

            Shared space and shared air with many animals.

            Increased contact with animals.

    Animals may appear to be healthy but carry infectious diseases.

    What kinds of animals transmit Zoonoses?

    Cattle, Swine, Goats, Cats, Dogs, Ticks, Squirrels, Raccoons

    And Other wild animals.

    How are diseases transmitted?

    Every day contact.

    Transporting carcasses and By-products

    Scratches or bites

    From milk and from milking

    Contaminated soil

    Contaminated meats.

C.       What are the common Zoonotic Diseases?

1.   Campylobacter

Common carriers:  Cattle, Sheep, Pigs, Dogs, Rodents and Poultry.

Transmission:  Direct contact with contaminated food Contaminated animals

Clinical Presentation:  Stomach ache, nausea, headache, diarrhea.

 

2.  Salmonellosis

Common carriers:   Cattle, Cats, Dogs, Horses, and Poultry.

Transmission        :   Direct contact with animal or feces, Food contamination from infected animals

Clinical presentation: Chills, fever, headache, diarrhea and vomiting.

 

3.  Encephalitis

Common Carriers:  Horses and Rodents

Transmission         :  Mosquito bite, tick bites.

Clinical presentation: Lethargy, fever, headache, and disorientation.

 

4.  Rabies

       Common Sources:  Cats, dogs, raccoons, bats, foxes and skunks.

Transmission       : Animal bites, contact with infected tissue, fluid and

                                 Feces.

Clinical Presentation:  Fever, headache, confusion, seizures, excessive

                                       Salivation and death.

 5. Psittacosis

Common carriers:  Pigeons, parrots, turkeys, and parakeets.

Transmission : Inhalation from infected birds, carcasses,

secretions, and contaminated facilities.                                   

Clinical Presentation:  Fever, headache, and pneumonia.

 

6.  Ringworm

Common carriers:  Cattle and Cats

Transmission        :   Direct contact

Clinical Presentation:  Skin lesions

 

7.   Toxoplasmosis

Common carriers: Cats, sheep and undercooked meat.

Transmission        :  Ingestion of infected meat, fecal contaminated soil.

Clinical Presentation: Fever, swollen lymph nodes. Abortion, still-birth.

 

8.   Scabies

Common carriers:  Dogs, and Raccoons

Transmission       :  Direct contact with infected animals

Clinical Presentation:  Itching skin lesions.

 

 

Prevention and Control.

 

1. Use an uncontaminated water supply.  Many diseases are carried in animal wastes that leak into water supplies

Make sure wells are properly constructed to avoid contamination

from livestock, animal and human wastes.

Add Chlorination to water.

Follow instruction for appropriate disposal of wastes.

 

2.  Prevent food contamination

Avoid unpasteurized milk.  Wash hands and clean and disinfect

kitchen surfaces before, during and after handling food.

                        Wash raw fruits and vegetables.

Cook food immediately after defrosting.

Cook all poultry to an internal temperature of 180 degrees, and

ground beef to an internal temperature of 160 degrees.

Refrigerate leftovers immediately.

 

3.  Avoid contact with diseased animals and prevent pets from contact with

Rodents and wild animals.  (e.g. Ticks carried by pets can cause Lyme

disease or Rocky Mountain Spotted Fever.  Raccoons, foxes

and other mammals can transmit rabies.)

 

Protect pets from getting and transmitting disease.

 

Vaccinate cats and dogs against rabies

Do not keep wild animals as pets.

 

4.  Prevent Tick Bites

Wear appropriate clothing.

Use Tick repellent

 

5.  Treat animal scratches and bites seriously

Wash the area with soap and water

Apply anti-bacterial medication

 

Major Zoonotic diseases in Kerala

Anthrax

      It is a zoonotic illness caused by Bacillus anthracis. Sporadic cases continue to be reported from many parts of the India.    anthrax meningo-encephalitis (AME) are also becoming common in patients infected with Anthrax. Most cases seem to occur in labourers who gave history of handling animal meat or skin of infected animals. In a few instances `insect bite' has been attributed. The meningo-encephalitic form of the disease has a very bad prognosis. Patients with this form of disease died inspite of treatment with high dose penicillin. The typical bacilli are easily seen in the CSF in AME cases and is diagnostic of the condition. The cutaneous form of illness has a benign course and responds favourably to penicillin treatment. The disease needs to be prevented with proper legislation for meat handling as well as effective immunisation of animals. (Indian Journal of Medical Microbiology. 1996 Apr; 14(2): 63-72 )

The clinical presentation is so characteristic that the diagnosis is rarely missed by physicians familiar with the disease. The exposed part of the skin begins to itch and there is a papule at the inoculation site. The papule becomes a vesicle and then a depressed, black, non-painful eschar 1-3 cm diameter that leaves a permanent scar. There may be surrounding edema and draining lymph nodes may become enlarged. If untreated, septicemia and death can occur in 5-20% of cases. If treated, fatalities are extremely rare.

How disease transmitted in human?Animals dying of anthrax produce enormous quantities of bacteria in their tissues. If the carcass is opened, the bacilli sporulate, contaminating the environment. Contaminated soil, contaminated animal products (including hides, fur, food), or environmental contamination by spores are also sources of the bacteria. The bacterial spores prefer alkaline environments (pH > 6) with abundant organic material, but can survive almost anywhere. Human to human transmission is extremely rare, even with pulmonary disease.

 

Leptospirosis

   [Weil's disease, Hemorrhagic jaundice (Leptospira icterohaemorrhagiae), canicola fever (L. canicola)

AGENT: Spirochete, Leptospira. Pathogenic leptospires belong to the species Leptospira interrogans

RESERVOIR AND INCIDENCE
Rats, mice, field moles, guinea pigs, gerbils, squirrels, rabbits, hamsters, reptiles, nonhuman primates, livestock, and dogs. *Rodents are the only major animal species that can shed leptospires throughout their life-span without clinical manifestations. Active shedding by lab animals can go unrecognized until personnel handling the animals become clinically ill.
TRANSMISSION
Handling affected animals, contaminating hands, or abrasions with urine, or aerosol exposure during cage cleaning are most common. The organism is often transmitted to humans by the urine of the reservoir host. The organism may also enter through minor skin lesions and probably via the conjunctiva. Many infections have followed bathing or swimming in infected waters.
DISEASE IN MAN
Ranges from inapparent infection to severe infection and death. Biphasic Illness a. Weakness, headache, myalgia, malaise, chills, & fever. b. Leukocytosis, painful orchitis (testes not usually enlarged), conjunctival effusion, and rash. Icteric leptospirosis (Weil's syndrome-usually caused by L. icterohaemorrhagiae) is the most severe form of the disease, characterized by impaired renal and hepatic function, abnormal mental status, hypotension, and a 5-10% mortality rate. Signs and symptoms are continuous and not biphasic.
DIAGNOSIS
Early in the disease, the organism may be identified by darkfield examination of the patient's blood or by culture on a semisolid medium. Culture is difficult and requires several weeks. A rapid diagnosis is made with the DOT-ELISA test.  

TREATMENT
Penicillins or tetracyclines.

PREVENTION\CONTROL
Vaccination in cattle, swine, and dogs Avoid swimming in or drinking from potentially contaminated water. Protect workers by providing boots and gloves. Rodent control. Drain wet ground. Doxycycline chemoprophylaxis for persons at high exposure.

 

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