Roundworm, Toxoplasma: Toxoplasma cati or T. gondii, are one-celled protozoa.
Common Sources of Infection—Raw and undercooked meat, water contaminated with the eggs and cat feces.
Symptoms: Causes blindness in children. Most healthy individuals do not show symptoms of toxoplasmosis, but when they do occur they may appear to be a viral infection: enlarged lymph nodes, muscle pains, and fever.
Diagnosis and Prevention of Toxoplasma: Diagnosis is usually made by comparing symptoms of the patient with laboratory tests, such as seeing the protozoa in tissue or finding antibodies specific to Toxoplasma in the patient’s blood serum.
Prevention is the best option to prevent spread of Toxoplasma. Pregnant women must take care to cook her foods well to kill all cysts present in meat. Hand washing after working outside in the soil will help, and pregnant women should not change or being around cat litter. Freezing also will kill oocysts. Fresh produce should be peeled, or at least washed well.
Treatment: Sulfa drugs or a homeopathic made of Toxoplasma kills the parasite. We use Epstein Barr drops and Parasite/Amoeba/Protozoa drops in our practice. This one is more common in AIDS patients and those with severely challenged immune systems.
Here are a couple pictures of Toxplasma eggs in a cat fecal floatation.
Toxoplasma Life Cycle: Toxoplasma has a complicated life cycle and is an organism capable of infecting many mammals and birds, but its main host is the cat. Only in the cat is the full life cycle of the parasite able to be completed. Initially the cat may get infected from capturing and eating an infected mouse or bird. The meat of the infected animal has pockets of a special form of Toxoplasma called bradyzoites, which are released from the meat into the cat’s small intestine soon after ingestion. The parasite grows and multiplies within the cells lining the cat’s intestine. This phase of the life cycle is called the intestinal phase, and eventually results in the formation of oocysts. These are released by large numbers into the cat’s feces but are not infectious at first. After a day or so in the environment they mature or sporulate into infectious oocysts, which then are not only resistant to chemicals and drying, but also can infect whatever mammal happens to eat them. They can persist in the environment for months and be carried about by rain, wind, earthworms, and insects (another good reason for routine worming!) They may eventually end up on produce or on pastures where different grazing animals may ingest them as they graze. They might also get into irrigation water to be used to water produce which may be for human consumption.
The other life cycle phase is the extra-intestinal, as it involves the parasite leaving the intestine (as the motile form called tachyzoites) and entering other cells within different organs in the body. The parasite forms a special cyst called the zoitocyst within the animal’s muscle, brain, lymph node or other tissue. Within these cysts the bradyzoites can persist for many years, often without harming the host, as long as the host has a healthy immune system. It is also this extra-intestinal phase that is so harmful to the human fetus, as the motile form of the parasite may cross the placenta to infect the fetus. This may result in spontaneous abortion or either a stillborn or physically and/or mentally handicapped child.
The cat may have either of these life phases present or both, shedding oocysts while also having zoitocysts within its tissues. All other infected animals (including humans) only have the extra-intestinal phase present. Healthy individuals may have the dormant cysts present in their body and show little signs of infection for many years. The parasite also may be triggered to multiply and spread when something lowers the immunity of the host (HIV infection, chemo-therapy treatment, or some other combination of factors).
The fetus within its mother is still growing and developing its immune system, so it is more vulnerable in the early stages of its life, when the immune system is not yet developed. An infection to the fetus during the last trimester may not be as devastating to the fetus as some immune system functioning is present.
One wonders why we don’t pick up Toxoplasma more often—especially for those of us who own cats. Could it be that we build up immunity to this organism if our immune system is functioning? It would seem to make sense as serologic surveys show that 7-94% of various populations are infected with the organism and are usually symptomatic. The disease occurs worldwide.
If an infection is found, there are antibiotics which can be taken, so early diagnosis is especially urgent for those pregnant or immunocompromised. Children as well are at risk.
References:
- The Merck Manual, 15th Edition
- Picture Reference: Veterinary Parasitology book