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An overview of ToxoplasmosisDr Shifa Ul HaqUVAS, Lahore-Pakistan

+Introduction

Toxoplasmosis is a zoonotic disease caused by T gondii

It belongs to phylum Apicomplexa, family Sarcocystidae

It’s derived from a Greek word “Toxon” mean bow as unique crescent shaped trophozoites, half the size of RBC

The parasite was 1st observed in rodents in 1908

In 1970 parasite life cycle was studied

+Introduction

Infection is seen in wide range of animals, birds but doesn’t produce disease in them

It can virtually infect all warm blooded animals

Members of Felidae family are final hosts that

excrete oocysts

An infected cat excrete 300,000 to 100 million oocysts in 10-20 days

+Introduction…

In USA 22% of population of 12 years old is seropositive

Seroprevalence increased with age

High seroprevalence in countries where undercooked meat is eaten like France and central America (Costa Rica, Guatemala, Honduras etc.)

In some communities up to 95% population is seropositive

Infection is high in hot, humid condition and low altitude

Cysts are highly resistant, survive even up to 18 months

+Life Cycle of Toxoplasma

Unsporulated oocysts shed in cat feces, take 1-5 days to sporulate and become infective

Intermediate host ingest oocysts>sporozoites released>penetrate epithelial cells and invade macrophages

Divide by endogony (merogony) and make two daughter cells> cell rupture> tachyzoites released and attack new calls

If immunity prevails development slows down and tachyzoites become bradyzoites and encysted in the tissues

If cat eat infected tissue, merogony occurs in intestinal cells and secrete oocysts in the fces

+Life Cycle of Toxoplasma

+Routes of Transmission

1. Foodborne

Undercooked, contaminated meat esp. pork, lamb

Accidental ingestion; not hand washing, contamination with knives, utensils, cutting boards

+Routes of Transmission

2. Animal to human Cats eat infected tissues and rodents, birds so get

infection. Cat passes millions of oocysts in environment after 3 week of ingestion. Human get infection if swallow accidentally

Cleaning contaminated litter box

Drinking contaminated water

Eating raw fruit and vegetable

No hand washing

+Routes of Transmission

3. Mother-to-child

During pregnancy infection can pass disease to fetus

Congenital Toxoplasma infections can cause serious eye, ear, and brain damage in new born.

If infection in early pregnancy, immunity will control

If new infection in last trimester: Miscarriage Still birth Disease in infant

+Diagnosis

Serologically by IgG and IgM can be used

Amniotic fluid of fetus for the detection of parasite DNA

MAT- Modified Agglutination Test for detection of antibodies in blood and serum

MRI and Computed Tomography for brain

Dye-Test (DT) Sabin-Feldman Test

+Treatment

The majority of affected people have no symptoms, usually a self-limiting disease in healthy persons

But serious problem is seen especially in immunodepressed and in pregnant women

If symptoms develop: muscle stiffness, swollen lymph nodes, confusion, headache, poor coordination

+Treatment

Combination of pyramethamine, 50mg on day 1st followed by 25mg/day and sulphadiazine 1-1.5 gram 4 times a day for 3-6 weeks

To prevent bone marrow toxicity folic acid 10-15mg/day

Dexamethasone 10-15mg/day also recommended during infection

During pregnancy Spiramycin 1gram/day

During 4th month of pregnancy pyrimethamine 50mg twice a day. Then pyrimethamine 50mg/day with sulphadiazine 1 gram four times a day for 4-6 weeks

+Control of Toxoplasmosis

Meat should be cooked properly at 70 °C until there is no reddish color.

Freezing the meat for more than 3 days at -15 °C or at -20 °C for 2 days will kill bradyzoites cysts

Wash, peel vegetables and fruits

Wash knives, cutting boards, dishes, utensils

+Control Cont.…

Avoid untreated water

Wear gloves when handling soil like gardening

Teach children about importance of washing hands

Keep sand boxes covered

People who keep cats in their houses should dispose off their fecal

material daily, wash cat boxes/cages thus eliminating the oocysts

before they have chance to sporulate and become infective

A serological negative cat in the home of pregnant women should be

removed from the house because it could acquire a primary infection

and can contaminate the environment with oocysts

+Control Cont.…

Flies and cockroaches should be controlled because they

act as transport host for fecal oocysts of cats.

Keep cats indoor and feed canned, cooked or frozen feed

Don’t adopt stray cats, and if pregnant

Use carbolic acid to kill oocysts in the soil, floors etc.

Educate people to avoid eating raw vegetables &

undercooked meat

+Have a Nice Day!

Dr Shifa Ul HaqUVAS, Lahore-PakistanTo contact me please Google “Shifa Ul Haq”