Lice v. Eggs

European typhus fever, also called "spotted fever'' and "ship fever," is not to be confused with typhoid fever. For generations it was the scourge of armies, and it still flourishes in Poland, Russia and the Balkans. It is transmitted by lice and fleas (hence delousing stations in the World War). The disease is due to a cosmopolitan virus called Rickettsia prowazeki,* which dwells in the intestines of the filthy little insects. Vaccines made from dead typhus viruses provide immunity from the disease, but such vaccines are difficult to make, for Rickettsia prowazeki cannot be easily cultured in artificial mediums, thrives and multiplies best in its natural habitat. Chief European vaccine maker is Professor Rudolf Weigl of the University of Lemberg, Poland. Last week the Paris weekly Marianne described a visit to Professor Weigl's laboratory.

Professor Weigl, said Marianne, ties a louse on a glass slide with a paper band, places it under a microscope. With a syringe and a glass tube fine as a hair, he injects a tiny drop of solution containing the virus, previously procured from infected guinea pigs, into the louse's intestinal opening. Then he imprisons the louse in a cage about the size of a matchbox, which has one side covered with fine silk gauze. Through the gauze the lice stick their mandibles. With these they suck blood from the arms of Professor Weigl and his wife (who have already had typhus, are now immune). After a ten-day incubation period the lice are dissected. About 150 intestines are placed in a sterilized mortar with a few drops of glycerin and carbolic acid (to assure sterility), and Dr. Weigl pounds the mess with a sterilized pestle. Result: one dose of immunizing typhus vaccine. At this rate, said Marianne, Professor Weigl makes less than one hundred life-saving doses a year.

From the U. S. Public Health Service last week came a new, streamlined mass-production method of culturing Rickettsia prowazeki. Bacteriologist Herald Rea Cox of the Rocky Mountain Laboratory at Hamilton, Mont., announced that he had injected the yolks of fertile, six-day-old chicken eggs with viruses of typhus fever as well as those of the related Rocky Mountain spotted fever, which occurs chiefly in Western States.

He used a thin needle, 1 1/4 inches long, which he passed through a tiny opening in the air-sac end of the egg. After he withdrew the needle, he sealed the hole with paraffin. In three or four days he removed the infected yolks, dried and ground them, diluted them in salt water, produced a remarkably virulent suspension of Rickettsiae, which lost none of its power when passed through ten series of eggs. "The technique," said Bacteriologist Cox, "is very simple, and permits a minimum of contamination." The simplicity of this operation should permit him to make thousands of doses of typhus vaccine in the time it takes Poland's Weigl to make one.

*Named after Howard Taylor Ricketts of Findlay, Ohio and Stanislas Josel Mathias von Prowazek of Germany, independent workers on the virus. Both died of typhus fever during the War.

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