Bubonic Plague in the United States | 1966 Medical Educational Film

During the last 15 centuries, many important plague pandemics have been recorded. The pandemic of the sixth century that began during the reign of the emperor Justinian and involved the whole Roman world. The black death of the 14th century which killed an estimated 25 million people or 1/4 the population of Europe at that time. The pandemic of the 15th, 16th, and 17th centuries, which culminated in the great plague of London, and the 18th century that witnessed the terrible outbreak of plague in Marseilles, France. and the present pandemic that began in 1894 and is now receding. The disease which appears to have a strong long-term cyclic tendency flares up on a global scale and then slowly retreats to smolder in endemic centers. Between pandemics, notable epidemics have occurred in countries of every major continent on Earth, including the United States. Around the turn of the century, a number of instances were reported of human plague cases on board ship. It is not surprising, therefore, that the first recorded cases of plague within the borders of the United States were on ships arriving at San Francisco, Fort Townsen, and New York City. Plague spread from various ports of the world and it is believed that it was introduced into this country and other ports of the world by flea bearing and plague infected rats escaping from docked ships. These shipborne rats in turn infected the local rats in port areas and caused epidemics in the urban residents particularly in the larger seapport cities. Then the majority of plague cases in the United States occurred in port cities on the west and Gulf coasts. Today in the western third of the United States, plague, a natural disease of wild rodents, is known to exist in 15 states. And although not definitely determined, infected rodents may exist in other parts of the country. The reservoir of plague in silven areas and the source of flea infection is a series of rodents, especially the ground squirrels, chipmunks, meadow mice, wood rats, prairie dogs, marmets, and other animals such as rabbits. Bubanic plague is the most common form of plague. The primary transmitter of bubanic infection is the flea, especially the oriental rat flea, xenopsula kopus. The causitive agent of plague is the rod-shaped bacteria pasteurella pestus. Plague among wild rodents of fields and woods is known as svatic plague. It is suspected that plague in these rodents has long existed in silvatic areas before epidemics occurred in port cities. Today, human plague cases are contracted from wild rodents or their fleas in silven areas. In some camping areas, wild rodents and their ectoparasites are especially prevalent. The present knowledge of the distribution and incidence of wild rodent plague in our western states should be warning to persons who camp or hunt in these areas. The handling or close contact with wild rodents should be avoided. Plague infection is possible from handling silven rodents, especially if these animals are sick, slow, and easy to catch. The outdoor visitor to parks and tourist

attractions in Silvatic regions should listen and heed the warning of park rangers to avoid all contact with the small rodents and animals in the camping areas. Hunters should not pick up or handle these small rodents which they have killed just for sport. The safest course is never to handle wild rodents, dead or alive. Cities with booming populations face perhaps the greatest possibility of a major outbreak of plague. as the suburbs stretch out into the country and as more and more people crowd into these and silven vacation areas. While the building of suburbs makes a habitat eventually unsuitable for appreciable wild rodent populations, there is an initial period of joint tenency by people and rodents. A condition theoretically ideal for the propagation of plague. The intermingling of silvatic rodents with commensal rats and the interchange of fleas infected with the plague basillus pasteurella pestus may transmit bubanic plague from animal to animal and ths to man. Bubonic plague in man if not diagnosed and treated early may progress to highly contagious pneumonic plague and fence spread from man to man in epidemic proportions. Bubanic infection with plague basilli pasturella pestus often results in a fatal disease in human cases. Plague infection is due to the bite of fleas or sometimes by direct contact of man in handling infected animals. Infection generally results in swollen lymph glands called boss, hence the name bubonic plague. If the bubo is obscure and the blood culture is positive, the infection is referred to as septasemic plague. In some cases of bubanic plague, the infection may progress to the lungs, causing secondary pneumonic plague, a disease that is usually fatal and highly contagious. A person with pneumonic plague may transfer this most infectious and contagious disease to another person by contact, close association, or by conversation with another. Plague is one of the internationally reportable quarantinable diseases. The international sanitary regulations require that port cities, especially where plague was formerly epidemic, be under constant surveillance and that ships arriving at these ports be kept under continuous surveillance. The ship's officer is required to show a certificate of inspection declaring that his vessel has been inspected and is free of rodent and insect infestation. Rat guards and other preventive measures are maintained to prevent rats from escaping or getting aboard ships. The most effective known plague control methods in port cities and other urban areas are the use of all possible preventive measures against the reservoir and transmission of the infection. Periodic surveys in endemic and in potentially epidemic areas are made to determine the prevalence of rats and rat fleas during surveys. is when rodents bearing plague infected fleas are caught, an immediate control program is instituted by a focal attack on fleas with insecticides. Suppressive measures against rats in these and other urban areas are by trapping or by poisoning. And with special emphasis on permanent control methods by the rat proofing of buildings by closing openings with imperous materials and reduction of rat harborage and breeding places. where new housing projects are built near the perimeter of growing suburbs adjacent to wild rodent habitats in brushy areas and initial surveys have determined the presence of plague

infected rodents. A systematic program of rodent flea control should be instituted where svatic plague has been epidemic or is now endemic. Continuous surveillance and periodic surveys are carried on by investigation teams to determine the prevalence of rodents and rodent fleas. Surveillance teams carry equipment to each trap site for field processing of any rodents caught. Meadow mice microis frequently are involved in episoatics and may be primary plague reservoirs in many localities. Rodents captured are lightly etherized and brushed for fleas. Fleas brushed from each rodent caught are collected on the tip of a small brush and then are transferred to a labeled vial of 2% saline in which they are carried to the laboratory for identification, recording, and processing. Dead rodents found in the field are carried to the laboratory for autopsy and examination. Survey teams have operated at greatly increasing distances from the west coast as plague in field rodents has been found farther and farther east. In areas where epzoatic plague has occurred, large numbers of fleas are collected by moving a white flannel cloth into rodent burrows. fleas collected, many of which may be infected, are placed in vials and examined in the laboratory. Prevention or control of episoatics of wild rodent plague in large silvatic and camp areas are accomplished best by area dusting with insecticides having long residual properties. Control of fleas with insecticides to prevent plague transmission has taken a place of primary importance in plague control. However, it should be emphasized that control of plague transmission in such large silven areas is only a special emergency measure with clearly limited objectives. In this area where temporary camps have been located, in addition to flea control, the fosai of wild rodent plague that threatens humans must be located and kept under surveillance so that control measures may be instituted rapidly when the need arises. In smaller silven areas, use of insecticide bait boxes will significantly reduce fleas on wild rodents. Bait is placed in the box to attract rodents. Insecticide is placed at both ends. While feeding, insecticide adheres to the rodent's fur. Bait boxes in camp areas are effective for flea control on small rodents. Where actual fosai of wild rodent plague are found near camping areas, parks or other recreational areas, a combined operation of rodent and flea control is instituted. Rodents are controlled by use of poison baits, powders, and sprays. And traps also are used for collection of chipmunks, ground squirrels, field mice, and other small mammals. In silvin areas, ground squirrels are regarded as one of the chief reservoirs of plague. Like some meadow mice, they are abundant and susceptible to plague infection. Fleas combed from these animals trapped where episoatics of plague exist are often infected with the plague organism. Rats trapped in urban areas are individually placed in paper bags with identification tags and brought to the laboratory where their fleas are removed for subsequent examination. Continual surveillance of rat and rat flea populations in urban areas, including suburbs contiguous with fosi of wild rodent plague, is an important prerequisite for the prevention of human plague. Fleas received in the laboratory from surveillance teams are examined under a microscope and identified as to species by the use of a strong translucent light

beneath the stereoscopic microscope. It is possible to identify the fleas just as they are received from the field collections and 2% saline without clearing and mounting. After the fleas are identified and recorded, they are crushed and preerated in mortars to be inoculated later into laboratory test animals. This guinea pig, a laboratory test animal, is carefully clipped for inoculation. The crushed flea treacherate is inoculated into the test animal for the detection of plague in the fleas collected from a rodent. Development of infection in the guinea pig after inoculation is followed in the isolation room. Here the growth of a booo on the test animal is measured. Autopsies are performed on rodents brought in from the field and those that died in the laboratory. Specimens include rats, wild rodents, and laboratory test animals such as guinea pigs and mice. Here, the autopsy of the guinea pig that was inoculated with the crushed flea titerate shows a typical booo infected spleen. liver and lung. This scientist is making a close examination of the pathology of the animal and removing certain organs for bacteriological culture. The plague vector efficiency of various wild rodent fleas is determined by established laboratory techniques. Fleas are first infected on mice with a terminal plague infection and are then fed on a clean mouse. When a flea feeds on the blood of a rodent with plague, it serves as a minute incubator for the germ. As a result, it often develops a blockade of the esophagus and stomach caused by growth of pasturella pestus. Such a flea may transmit infection by the regurgitation of basilli from the mass in its intestinal tract or by its contaminated mouth parts. This shows a wild rodent flea that had fed one day previously on an infected mouse. Note small dark plague mass in the posterior half of the stomach. The same flea 33 days after infection has a dark plague mass in the esophagus and for stomach and black masses in the distended stomach. 40 days after infection, a complete blockage of the stomach is seen. During the three days before the fleas's death, on the 42nd day, it transmitted plague to eight mice, all of which died. Patients must be isolated in cases of pneumonic plague and special masks and protective clothing should be worn. Although pneumonic plague can now be cured if diagnosed and treated early, it is best to prevent it by diagnosis and cure of bubanic cases. Physicians should regard with suspicion a history of contact with wild rodents in western recreational and other silvatic areas and should consider all cases of inguinal, axillary or cervical lympodinopathy as suggestive of plague. Immediate treatment with streptoycin or tetracycline antibiotics or sulfodiaine should be considered without waiting for laboratory confirmation. Diagnosis of plague is confirmed in the laboratory by demonstrating the infectious agent in fluid aspirated from

boss in blood or in sputum from a pneumonic Conventional methods of detecting plague while slow but in some instances very sensitive are still used and are necessary in the laboratory diagnosis. Only the isolation of pasteurella pestus from a specimen constitutes absolute proof of plague. However, with development of the fluorescent antibbody staining technique, a very rapid method for identification of pasturella pestus and its antigens is now available. Identification of plague bacteria may be made within hours after receiving smears by the fluorescent antibbody technique. In areas where plague is found or suspected, specimens should be sent to the San Francisco field station communicable disease center, United States Public Health Service for specific determination of the eeologic agent. Investigations carried on by the CDC field station supply local authorities with specific information necessary for application of control measures. World Health Organization regulations require continuous surveillance in areas where plague has been epidemic or is now endemic. Down through the centuries, innumerable, exotic, and varied have been the forms of treatment used to exercise or eradicate plague to the present day when streptoyosin and the tetracycline antibiotics have proven highly effective for all forms of plague. If therapy is begun early enough, at least within 24 hours of onset. If antibiotics are not available, sulfanomides may be used. Early treatment is of critical importance since delay may be fatal or may allow the development of secondary pneumonic plague with its great danger to all contacts of the patient and its epidemic potential. But in the final analysis, a continuous program of constant and vigilant surveillance of rodents and flea densities and appropriate diagnostic and control measures still assure the best long range protection in those areas susceptible to the infection by the ageless and dread killer. plague.