Archive for Wednesday, October 24, 1990


October 24, 1990


A Kansas University Medical Center researcher has developed a vaccine to control an infectious parasite passed primarily from cats to 500 million people worldwide.

Jacob Frenkel, KUMC professor of pathology, said the vaccination of cats to control toxoplasma would primarly benefit pregnant women, children and farm animals.

Frenkel's work has led to an agreement between KUMC and Paravax Inc., Mountain View, Calif., to produce the first vaccine that immunizes cats against toxoplasma.

In a separate agreement, Paravax will work with Mobay Corp. animal health division in Shawnee to commercialize the vaccine. Mobay is a Bayer USA company.

Cats are a major source of toxoplasma. Although the animals suffer relatively few effects from the parasite, they can pass the infection to humans and farm animals.

"UNTIL NOW, there has been no satisfactory way to prevent toxoplasma infection," said Lynnor Stevenson, Paravox president.

"By inoculating cats . . . we can reduce the incidence of the disease and its transmission to humans."

Frenkel, who has studied toxoplasma for 48 years, said the infection can give rise to disease mainly in babies, children and immune-deficient AIDS patients.

The infection severely affects the fetus. The 9,500 babies born with toxoplasmosis each year in tthe United States suffer mental retardation and vision or hearing problems.

Nearly all kittens are infected with toxoplasma, but few get sick. Cats develop an immunity to the infection, but shed eggs of the parasite in their feces.

FARM ANIMALS are infected with toxoplasma when they come in contact with egg-contaminated soil. Humans can be infected from garden soil, cat litter or by handling raw meat.

Frenkel developed a vaccine for cats to prevent them from shedding the eggs. The vaccine is a clone of a mutant form of toxoplasma created by a Dartmount Medical School professor.

A typical cat can shed 100 million of the highly infectious eggs. However, 84 percent of the kittens vaccinated have not shed a single egg, Frenkel said.

Most vaccines prevent disease only in the immunized animal. Toxoplasma vaccine, like the vaccine against rabies, reduces the problem of infected cats passing the disease.

"Importantly, the toxoplasma vaccine extends the benefits of animal protection to the general area of public health," Stevenson said.

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