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Toxoplasmosis

Dr. Md. Saroat Hossain

DVM, MS in Microbiology,

Rajshahi University,

Bangladesh

Toxoplasmosis

• Definition:

Toxoplasmosis is a zoonotic disease which affects nearly all warm blooded animals and man. It affects reproductive system, nervous system, skeletal muscles and eyes.

Epidemiology:

Etiology:• The disease is caused by parasite Toxoplasma

gondii. Toxoplasma gondii are found in three forms –

• (a) Tachyzoites which are the rapidly multiplying forms found in the blood and body fluids.

• (b) Cyst form which contains bradyzoites are slowly multiplying form found in body tissues.

Etiology

• (c) Sporulated oocyst voided in the faeces of cats.

• The parasite has got affinity for epithelial, reticuloendothelial and blood cells. The organism could be grown in monolayer of lamb testicular cells

Distribution:

• Toxoplasma was discovered in 1908 by Nicolle and Manceaux from north African rodent (Ctenodactylus gondii)

• The parasite is worldwide in distribution but the incidence is more in warm , moist climate than cold, dry climate.

Susceptible hosts

• Toxoplasma has been recorded in cattle, buffalo, sheep, goat, pig, dog, horse, cat and man.

Risk factors:

Pathogen risk factorsEnvironmental and management risk

factors

Risk factors

High rainfall which allows longer survival of oocysts on pasture.

Animal raised in cat free areas have almost no toxoplasmosis.

Oocysts are extremely resistant to external influences and can survive

in the environment for at least 1 year.

About 50 g of infected cat feces contain about 10 million oocystsand infection can be occurred by

ingestion of < 40 oocysts.

Oocysts are destroyed by exposure to temperature between 90C for 30 sec. and 50C for 2.5 minutes

• Most outbreaks in sheep & goats have been reported with exposure to

stored feed containing cat faeces.• Cat access to sows is also a risk factor

for disease in swine.

Mode of transmission:

• Toxoplasma has been reported to be transmitted by the following ways in man and animals-

(a) Through cat : The cat is the only definitive host of the parasite. Infected cats shed large number of oocysts in the faeces . Stray cats contaminate the soils around the human habitations and thus play a vital role in the transmission of toxoplasmosis.

Mode of transmission(cont’d):

(b) Meat & meat products :

Consumption of raw or under cooked meat or meat products are important source of toxoplasmosis.

(c) Congenital infection :

From infected mother ( dam ) to the fetus

Mode of transmission(cont’d):

(d) Other methods:

• Inhalation and ingestion of infected milk may transmit the infection.

• Infection has been traced to be transmitted through semen.

• Experimental transmission can be made by intramuscular , subcutaneous or intraperitonial inoculation of infected materials.

Life cycle of Toxoplasma sp:

Life cycle in final host:

• Cats become infected by ingestion of rodent whose tissues contain tachyzoites or bradyzoites.

• Infection also occur through the ingestion of oocysts.

• The cyst wall ( either badyzoites,tachyzoites or oocyst ) is digested in cat stomsch.

Life cycle of Toxoplasma sp(cont’d):

• The liberated organisms penetrate the intestinal wall and initiates schizogonas cycle followed by gametogonas development.

• The oocysts are produced within 3-10 days and shade within 1-2 weeks.

• The organisms also invade intestinal organ and development of tachyzoites, badyzoites, oocyst as in intermediate host.

Life cycle of Toxoplasma sp(cont’d):

In intermediate host:

The I.H(cattle) are infected by ingestion of sporulated oocyst.

Liberated sporozoites inter into cell wall and spread via hematogenus route and cause tachyzoites

Tachyzoites inter into cell and multiply by budding.

Life cycle of Toxoplasma sp(cont’d):

• Following this process 8-16 tachyzoitesaccumulated and infected cell ruptured and new cells infected.

• In most cases the host survive and antibody produced which limits the invasiveness.

• Followed by badyzoites formation.

Life cycle of Toxoplasma sp(cont’d):

• If immunity suppress, cyst may rupture releasing bradyzoites .

• Bradyzoites become activated and resume the invasive characteristics of tachyzoites.

• The F.H. is infected by the ingestion of either bradyzoites, tachyzoites containing tissue of I.H.

Life cycle of Toxoplasma sp:

Clinical findings :

• Cattle and buffalo- high rise of temperature and enlargement of lymph node.

• Sheep - abortion in ewes.

• In goats- high rise of temperature, dyspnea, diarrhea, muscular tremors, paresis of hind quarters, erythropenia and anemia.

Clinical findings(cont’d):

• Pig- Abortion, still births in sows and dyspnea and wasting in young piglets.

Some pictures of Toxoplasmosis:

Fig. Enlarged lymph node in sheep Fig: aborted fetus

Diagnosis:

• Clinical signs are non- specific and organism is difficult to demonstrate. Therefore, diagnosis in man and animals is accompanied by serological tests.

(a) Isolation of T. gondii – Parasites can be demonstrated from lymph fluid, placenta, cotyledons and muscles.

Diagnosis:

(b) Methylene blue dye test: Sabin and Feldman first described it.

• This test now a days is carried out by in microtitre plates and can be judged by employing empty microscope.

Diagnosis-

(c) By complement fixation test(CFT).

(d) By indirect hemagglutinationtests(HI).

(e) By direct agglutination tests.

(f) By fluorescent antibody tests(FAT).

(g) By enzyme linked immuno sorbent assay (ELISA)

(h) By DNA test.

Treatment:

(a)There is no satisfactory treatment. Drugs like pyremethamine and sulphonamide are effective.

• SDDS (diaminodiphenyl sulfone)@ 100mg /kg body weight for 14 days is the most effective treatment. Drugs which have been used in man and animals are as follows.

(b) Sulphonamide @ 10 mg / kg b.wt. orally once.

Treatment(cont’d):

(c) Trimethoprim & sulphamethoxazole @ 30 mg/kg intrauterine.

(d) Clindamycin 120-150 mg/kg bwt. I/M is effective against feline toxoplasmosis.

Drugs suggestion:Trade name Composition

& generic name

Generic dose Trade dose Pack size Company

Inj. Diadin 333 mg sulphonamide

10 mg/kg 1 ml/ 34 kg 30, 100 ml(1 ml= 333 mg)

Reneta

Sulphatrim Sulphadiazine1000mg & Trimethoprim 200mg

15-30 mg/kg 1 bol./40 kg bwt Sulphadiazine1000mg & Trimethoprim 200mg/bolus

Techno

Jasotrim Sulphamethoxazole-1000 & trimethoprim-200 mg

30-40mg/kgorally & 60-80 mg/kg in uterus

1 bol./ 40 kgSulphamethoxazole-1000 & trimethoprim-200 mg/bolus

Jayson

Control:

• Control programme may be aimed based on three methods-

(a) Epidemiological control-• Lowering of cat population in endemic

zones.• Cat should not be allowed to feed raw meat.• Cat faeces should be properly disposed

through burning.• Hands should be properly cleaned with soap

after handling of raw meat.

Control(cont’d):

• Pregnant lady should not handle soil and raw meat.

• Raw meat should not be consumed.

(b) Chemotherapeutical control- Prophylactic measures should be taken with drugs shown in treatment.

(c) Control by immunization- No fruitful vaccine is available. A vaccine containing T. gondiiused to control disease.

Public health significance:

• Toxoplasmosis in man can occur as prenatal or acquired infection.

• Prenatal or congenital infection damages the eye and CNS characterized by blindness & convulsions.

• Acquired infection is less severe and characterized by lymph adenopathy, choriorenitis and general malaise.

Prescription of Toxoplasmosis:Dr. Wahidur Rahman

Address: DVM, Rajshahi University

Description of animal:

species: Breed: Sex:

Age: Body weight:

Clinical findings: Rx.

• High temperature 1. Bolus. Cotrim-vet x 6

• Enlarged lymph Sig: 3 boli at a time 12 hoursly intrauterine

node 2. Inj. Diadin- 30ml x 6 vial

• Abortion Sig: 60 ml at first days & 30 ml next 3 days I/M

Wahidur

Advice: Avoid natural cervice 21.05.14

Signature & Date

Thanks to all