Science October 1981

By KEITH E. JACKSON

Science

Rabies: record number of animal cases; new vaccine for humans

Animal rabies cases in Illinois by county, Jan. 1, 1981-Aug. 13, 1981 (as reported to Illinois Department of Public Health)

Keith E. Jackson is staff scientist for the science unit of the Illinois Legislative Council.

A RECORD number of animals in Illinois have been diagnosed as having rabies this year, according to the Illinois Department of Public Health (IDPH). As of August 13, 442 animals had been diagnosed as having rabies. There were 524 confirmed animal rabies cases in all of 1980.

Skunks, which can live for weeks or even months with the disease, accounted for 365 of the reported animal rabies cases so far this year. For this reason, H.B. 405, a bill revising the Illinois game code sponsored by Rep. Jacob John Wolf (R., Chicago) was amended in the Senate to permit the hunting of striped skunks year-round. The bill has yet to be signed by the governor.

The remaining 77 animal rabies cases reported in Illinois as of August were distributed among cattle (27), cats (15), bats (10), dogs (9), foxes (5), raccoons (5), horses (4), badger (1) and sheep (1). Rodents, including rats, mice and squirrels, are rarely found to have rabies.

Although no cases of rabies in humans have been reported in Illinois since 1954 (and only one in the entire country since November 1979, according to the Center for Disease Control in Atlanta), the number of people receiving rabies vaccine has increased along with the number of reported animal cases. In the first seven months of 1980, 242 individuals in Illinois received rabies vaccine. In the first seven months of 1981, 344 individuals received vaccine — an increase of 29 percent.

Currently there are two rabies vaccines that are used in the U.S. IDPH is contemplating changing its method of distributing the newer, less painfully administered vaccine, which also has fewer side effects. This new vaccine, which was licensed for use in the U.S. by the Food and Drug Administration in 1980, is called human diploid cell vaccine (HDCV). The other drug is called duck embryo vaccine or DEV, but it will not be available after November. Eli Lilly and Company, the sole producer and marketer of DEV, announced on August 10 that it will stop domestic sales of DEV on November 30 and stop foreign sales the second quarter of 1982.

HDCV is an inactivated virus vaccine prepared from rabies virus grown in human diploid cell tissue culture. HDCV is considered more effective than DEV. It has also been found not to have the serious side effects — systemic and neuroparalytic reactions — that have been associated with DEV vaccine. Also, only five intramuscular injections of HDCV are needed to prevent rabies after exposure compared to the 23 very painful doses of DEV that must be injected subcutaneously in the abdomen, lower back or lateral aspect of the thigh.

October 1981 | Illinois Issues | 15

Rabies: recognizing the symptoms

RABIES is one of the oldest known human diseases and, if untreated, it almost invariably results in death. Only three cases of recovery from rabies have been reported. Animal rabies was identified in early Middle Eastern civilizations before 2300 B.C. Human rabies was identified in AD 100 by Celsus (a celebrated Roman medical encyclopedist) who recognized hydrophobia, the fear of water, as a symptom. Celsus recommended cautery, burning the skin tissue at the site of the animal bite with a hot iron, as a preventive measure for rabies. Cautery was the treatment of choice for rabid animal bites until 1885, when a rabies vaccine was introduced by Louis Pasteur.

Rabies is caused by a virus belonging to a group of viruses called rhabdoviruses (Greek rhabods, rod) so-called because of the bullet-like shape they display when viewed with an electron microscope. Humans develop rabies as a result of an animal bite, although a few cases of nonbite-induced human rabies have been reported. But those cases were caused by exposure to environments that contained rabies virus in extremely high concentrations, such as caves where aerosolized rabies virus in bat urine was present, or infected and aerosolized tissues in laboratories. Experimental studies have shown that rabies can be produced when the rabies virus comes into contact with: mucus membranes or conjunctiva membranes (which line the eyelid and surround the eye), or broken skin when the virus is present in high concentration in the saliva of a rabid animal.

Rabies in dogs can become visible as soon as 10 days after infection, but it usually takes from three to six weeks. Early signs are an alert-troubled air and a change in the dog's disposition. Restlessness, snapping at imaginary flies, and licking or gnawing at the site of the bite follows. Rabid dogs are often fearful and hide. A paralytic syndrome begins between the third and fifth day after the early signs. The syndrome takes one of two forms; "furious" or "dumb." A dog with the furious form is restless, snaps at moving objects, and toward the end hangs his lower jaw and drools. This is followed by paralysis and convulsions. In the dumb form the dog may appear to have something lodged in its throat, is not irritable and rarely bites, and is apathetic and likely to hide.

Cat rabies follows a course similar to dog rabies. Horses and cows with rabies show irritation, restlessness, and unusual aggressiveness. The main characteristic of rabies in wild animals is the lack of fear of man or large animals. An unprovoked biting attack by a wild animal should raise suspicion of rabies. Keith E. Jackson

According to Carl Langkop of IDPH's division of disease control, HDCV can only be purchased by tax-supported agencies or hospitals. HDCV is manufactured by a French company, Merieux Institute, Inc. which is licensed by the U.S. Food and Drug Administration to sell HDCV in the U.S. However, the company does not own a U.S. patent for the vaccine, which prevents the company from selling it in the U.S. But a loophole in the U.S. patent law allows tax-supported agencies or public hospitals to purchase HDVC.

There are 45 public hospitals in Illinois that are qualified to purchase HDCV, but to date only one, Moline Public Hospital, is known to have purchased the vaccine, although there may be others. The Great Lakes Naval Base and Scott Air Force Base hospitals have purchased HDCV.

Since 1925, IDPH has had a rabies vaccine program in which the agency purchased rabies vaccine and provided it free of charge to physicians. Under this program a physician treating a suspected rabies case would contact the agency, which in turn would investigate the case to determine if postexposure rabies treatment was necessary. If so, IDPH would release the vaccine to the physician.

In a June 1, 1981 memorandum addressed to local health departments and regional offices in Illinois, William Kempiners, director of IDPH, proposed changes in this long-time program. Instead of IDPH being the central distribution point for vaccine in the state, a network of about 15 rabies vaccine distribution sites scattered over Illinois would be established. Each site would receive 10 doses of HDCV (enough to treat two patients) from IDPH as a seed to establish an initial supply. The site would sell HDCV to any physician or his patient ordering the vaccine.

Currently, HDCV costs $45 per dose when purchased in quantities of less than 100 doses, so the necessary five shots cost about $225. The use of a globulin, which provides rapid immune protection and is administered only once, is recommended and costs about $225, resulting in a total cost of about $450. About 76 percent of Illinois rabies patients receive the globulin. The price for the rabies vaccine and globulin does not take into account any additional charges assessed by hospitals or physicians.

According to Langkop, Illinois residents can protect themselves from rabies by keeping their dogs' and cats' vaccinations current (once every three years for dogs and once a year for cats) and refraining from keeping pet skunks and raccoons, which are both susceptible to rabies and can possibly contract rabies from the rabies vaccine.

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