Bacillary Carrier State

BACILLARY CARRIER STATE, latent, not accompanied by any pathological symptoms, the presence of an infectious agent in the human or animal organism. The possibility of such a unique coexistence of a pathogenic microbe with the human or animal organism was vaguely surmised long ago. As early as the second half of the 19th century, Verneuil, and later Arnould, developed the hypothesis of "latent microbism," with Arnould teaching that in epidemic foci, many people, while remaining healthy, become carriers of infection. According to Arnould, the infectious agent in the bodies of such carriers exists in a non-pathogenic, saprophytic stage of its development and does not pass into the pathogenic, parasitic stage until particularly favorable conditions for such a transition are created in the carrier's organism. Arnould's ideas received their ultimate development in Koelsch, who, analyzing the history of epidemic outbreaks (typhoid fever, diphtheria, etc.), unclear in their origin, as well as the periodicity in the appearance of major epidemics, which seemed mysterious and causeless at that time, came to the conviction that infections and epidemics must arise spontaneously, autochthonously, and that the main factor in their emergence is not the infectious agent, but those living conditions that can exhaust and weaken the human organism, such as physical fatigue, poor nutrition, nervous shocks, etc. According to Koelsch's teaching, the infectious agent is ubiquitous, every person carries within himself the infection of typhoid fever, erysipelas, dysentery, diphtheria, meningitis, etc., but the infectious agent lives in the carrier's organism in the state of an innocent inhabitant and becomes pathogenic only under the influence of harmful living conditions that exhaust the carrier's organism. In other words, according to Koelsch's theory, every infection is, in its pathogenesis, an "autoinfection." It should be noted that such views on the origin of infection were held by the leading clinicians of England and France before Koelsch, for example, Murchison, Trousseau, and others. Koelsch formulated his theory of the spontaneous origin of infectious disease in the following words: "The autogenesis of an infectious disease follows from the general law governing the biology of pathogenic microbes, according to which the virulence of the latter fluctuates, increasing and falling within such limits that the same pathogenic microbe at one time remains in a state of complete saprophytism, at another time acquires clearly expressed pathogenic properties." The untenability of Koelsch's hypothesis about the ubiquity of infection and the saprophytic state of pathogenic microbes in the carrier's organism undermined the very meaning and epidemiological significance of the bacillary carrier state. The untenability of this hypothesis was revealed by the first bacteriological investigations of epidemics. In the late 1890s, Remlinger and Schneider, Losener and Sanarelli found the Eberth bacillus in the excretions of healthy people. In 1902, Chantemesse and later his student Decobret showed that the Eberth bacillus is sometimes found in the fecal masses of typhoid fever convalescents still 15-30 days after their clinical recovery. Thus, these works established the most important groups of bacillary carriers: 1) carriers of pathogenic microbes among a portion of the healthy population, 2) carriers of pathogenic microbes among convalescents. To clarify the question of the epidemiological significance of the bacillary carrier state, observations by R. Koch in 1903 on the pre-Rhine focus of typhoid fever were decisive. Koch established that in epidemic outbreaks of typhoid fever, by whatever paths it spreads (water, food products, etc.), the primary source of infection is always and everywhere either the patient himself or the healthy carrier of infection. This basic epidemiological position was confirmed by a whole series of subsequent works for the most diverse epidemics. According to this position, it is possible to successfully combat any epidemic only under the indispensable condition that anti-epidemic measures will be directed toward the localization and destruction of infection in its primary source, namely, in the organism of the sick person and the healthy carrier. At the present time, the doctrine of the bacillary carrier state, which has spread to almost all infections, is being energetically developed, but it is still far from its final formulation even in such basic points as questions about the pathogenesis of the carrier state, about the epidemiological role of carriers in various infections, etc. The boundaries of the concept of the carrier state cannot be considered fully established either. If we agree to understand by the carrier state every latent presence of infection in the human or animal organism, then this should include: 1) each infection in its incubation period, 2) cases of infection running unusually mildly, in the form of obscure, outpatient, or even completely asymptomatic clinical forms, as established, for example, by Griesinger for typhoid fever (typhus levissimus), by Nicolle for childhood typhus (infection inapparente), etc., 3) cases of clinical recovery from infection, in which the infectious agent continues to remain in the convalescent's organism for some time, and, finally, 4) cases of latent presence of infection in the organism of completely healthy people. The epidemiological significance of each of the listed categories of bacillary carriers varies for different infections. Here it is only important to note that the 3rd and 4th categories of bacillary carriers, i.e., convalescents and healthy carriers, play the most substantial role in the spread of epidemics. The excretion of infection can occur directly by the carrier himself, contaminating the surrounding environment with the excretions of his organism in which the infectious agent is present (saliva, sputum, urine, feces, etc.); it can occur through the agency of blood-sucking insects, which takes place, for example, in the carrier state of malarial plasmodia (Anopheles), in asymptomatic childhood typhus (body louse), etc. The bacillary carrier is dangerous only when he is a disseminator of infection in the surrounding environment, a direct or indirect excretor. However, different authors give different interpretations to the terms: "bacillary carrier state" and "bacillary excretion." Thus, Frosch calls bacillary carriers (Bacillentrager) persons who excrete infection for no longer than 3 months; persons who excrete infection for more than 3 months, he classifies as long-term excretors (Dauerausscheider). Prigge, Schumacher, Scheller, Martz, and others call healthy carriers of infection bacillary carriers, and convalescent carriers bacillary excretors. The first, in Prigge's opinion, are usually freed from the carrier state within one year; the second carry infection for years. Conradi divides carriers disseminating infection into two groups: 1) main carriers, to whom people who previously had a given infection belong, and 2) secondary carriers-healthy people who have never had this infection. Conradi asserts that not a single case has yet been established where the spread of infection was caused by secondary carriers; therefore, only main carriers are important for the epidemiologist. The causes giving rise to the carrier state and the pathogenesis of the latter are not fully clarified. It has only been established that this unique form of coexistence of a pathogenic microbe with the human or animal organism owes its origin to the interaction of a number of factors, namely: 1) the general condition of the host organism, 2) the anatomical and physiological peculiarities of the organ in which the pathogenic microbe settles, 3) the nature of the epidemic, 4) the biological peculiarities of the pathogenic microbe itself, etc. To understand the significance of each of the listed factors in the pathogenesis of the carrier state, one must answer the basic question: is the presence of a pathogenic microbe in the carrier's organism a matter of indifference for the latter, or is this a unique form of infection to which the carrier's organism reacts, if not with symptoms of a clear clinical disease, then with a protective restructuring of its cellular and humoral colloids. That the carrier state must be regarded as a definite period or as a unique form of infection is obvious for the first two categories of the carrier state: 1) the incubation period of infection and 2) its attenuated forms. The carrier state in convalescents represents a localized form of infection. Numerous investigations have established that the pathogenic microbe in the organism of convalescent carriers causes clear inflammatory changes at the site of its localization, for example, in typhoid and paratyphoid carriers most often in the gallbladder, in diphtheria carriers in the tonsils, in cholera carriers in the intestine and often in the gallbladder, etc. In all these cases, anatomical peculiarities or pathological changes of organs preceding the carrier state can play a favorable role for the selective settlement of the pathogenic microbe in them (for example, the tortuosity and hypertrophy of lacunae in the tonsils in diphtheria, the catarrhal condition of the nasal mucosa in meningococcal carrier state, etc.). The question of whether the carrier state in healthy people is a special kind of infection is almost not illuminated in the literature.

However, it is known that a healthy bacillary carrier, under the influence of factors weakening his organism, may present a picture of general illness, and that, on the other hand, every healthy bacillary carrier sooner or later recovers from his carrier state. Furthermore, it has been established with respect to certain groups of healthy bacillary carriers, for example, cholera carriers (Gluzman), that their sera give immune reactions with the corresponding microbe that are not inferior in strength to the reactions in the sera of convalescents or vaccinated individuals. Finally, there are observations proving that during epidemic times large groups of completely healthy population unknowingly acquire immunity to the causative microbe of the given epidemic. According, for example, to the data of Mironov and Belyavtsev, two-thirds of the healthy residents of the city of Krasnodar examined by them during cholera times showed clear serum immunity reactions against the cholera vibrio. All this allows us to consider B. in healthy people not as a simple form of coexistence of the macroorganism with the microorganism, but as a special form of parasitism of the latter, accompanied by profound internal changes in the host's organism. From this point of view, B., while apparently preserving full health, is an external expression of the equilibrium between the degree of immunity of the carrier's organism and those biological properties of the disease-causing microbe that it uses for self-defense and attack (stability of form, capsule, virulence, etc.). The degree of natural or acquired immunity determines, all other conditions being equal, in what form the encounter of the macroorganism with the disease-causing microbe will express itself: in the form of severe illness or 'attenuated' infection (as, for example, typhus in a little susceptible child population), or finally, simple B. The analysis of immunity acquired by the population during an epidemic shows that this factor lies at the basis of the pathogenesis not only of individual B., but also of those regularities that govern the development, course, and extinction of the epidemic outbreak itself. As collective immunity accumulates (Minervin, cholera 1920 in the city of Rostov-on-Don), mortality among the sick steadily decreases until the end of the epidemic, while the number of mild cases of infection and B. also steadily and progressively increases. Along with the general condition of the carrier's organism, the type of disease-causing microbe is of importance for the pathogenesis of B. It has been established, for example, that in South America the predominant types of meningococcus are C and D; conversely, in North America types A and B predominate. Furthermore, in the epidemiological evaluation of B., the typeness of the culture (atypical paratyphoid cultures of Frankel, Much) and the virulence of the carried microbe are taken into consideration. Particularly many works are devoted to elucidating the epidemiological significance of the virulence of Löffler's bacillus in diphtheria B. However, the data obtained here are contradictory and not entirely convincing. Golubtsov, for example, found among 10 diphtheria carriers: in 5 - non-virulent diphtheria bacillus, in 2 - weakly virulent, and in 3 - virulent (guinea pigs died). Klinger and Schocb from 120 diphtheria cultures from carriers recognized 57 cultures as non-virulent and 63 as virulent. The significance of virulence in the spread of epidemics by bacillary carriers remains an open question because the very sign of virulence is not, as Sauerbeck believed, constant and indisputable. Roux and Yersin admit the transition of virulent cultures into avirulent ones and back. Klinger and Schocb establish three types of cultures: 1) invariably virulent, 2) invariably avirulent, and 3) cultures with changing, usually disappearing, virulence. However, Ustwedt asserts that even a non-virulent culture can become virulent. Finally, some authors connect the duration of bacillary carriage with the morphology of the microbe. Thus, according to the data of Tartino, short Löffler's bacilli disappear in 3 weeks, medium-length ones in 4, and long ones in 5 weeks. The epidemiological significance of bacillary carriers, besides the biological properties of the microbe they excrete and the susceptibility of the population to it, also depends on a number of other factors. Among them, the most important are the category of the bacillary carrier, the frequency and duration of the carrier state. As for the category of bacillary carriers, it is generally recognized that convalescent and healthy bacillary carriers play the most prominent role in the spread of epidemics. The role of healthy bacillary carriers, compared to convalescents, is disputed by many authors. Thus, for example, Flax, Conradi, Mider, Meader, Doull, and others deny any significance of healthy carriers of diphtheria. The frequency of B. among convalescents and healthy people widely varies not only with different types of infections but also with different epidemics caused by the same infectious agent. The average figures for B. in convalescents after typhoid fever are determined at 5%, after paratyphoids at 9%, in healthy people up to 1%; in bacillary dysentery in both categories the percentage of carriage varies from 2 (Lentz) to 14 (Hermel), in cholera from 0.5 to 7, in diphtheria about 15, with variations from 0.5 (Becker) to 73 (Funkhauser), in cerebrospinal meningitis about 10, with variations from 1-2 (Gruber, Mayer, etc.) to 70.8 (Ostermann) and higher. The frequency of B. is closely connected with proximity to the sick person. Thus, for example, according to the statistics of Riemsdyk, among persons directly close to a diphtheria patient (parents, brothers, sisters) there is 66% carriage, among the caring hospital personnel 37%, among persons in the same dormitory with patients (boarding schools, barracks) 23%, among patients in hospitals with a diphtheria department 14%, among schoolchildren attending a school where cases of diphtheria were observed 7%, while among schoolchildren from schools where there were no cases of diphtheria from 0.27% (Graham) to 0.83% (Kober) carriers. The frequency of B. in some infections depends on sex and age. Thus, it has been established, for example, that the highest percentage of typhoid carriage falls on women (Conradi, Dri-galsky, Lentz, and others). According to Forster, for one typhoid carrier-man there are 3-4 carrier-women, and according to O. Mayer even 9 carrier-women. Cornet notes that among the number of women carriers 82% are married and only 18% are girls. This is apparently connected with age. According to the data of Kulesh, Klinger, and others, children give a significantly lower percentage of typhoid bacillary carriage compared to adults. Thus, for example, according to Klinger, on 2.9-34.7% carriage in children there are 72.6-97.1% carriage in adults. The reverse relations are encountered when studying the frequency of carriage in diphtheria. Doull, for example, points out that the percentage of carriage in children under 5 years equals 19.6%, from 5 to 9 years 38.8%, and over 9 years the number of carriers gradually decreases. The significance of bacillary carriers in the spread of infection is determined not only by their number but also by the enormous amount of infection that they throw into the environment. Thus, for example, according to the data of Caretto, in 1 cubic cm of urine of a typhoid carrier there are from 2,000 to 200,000 microbes. Uhlenhuth, Hegler consider that a carrier can excrete with urine up to 300 billion microbes per day. Hirschbruch found that 1 g of feces contains from 32.4 to 260 million microbes, of which from 45 to 100% are typhoid. The duration of the carrier state is no less important. In this respect all bacillary carriers are divided into two groups: acute and chronic carriers. The vast majority of bacillary carriers belong to the acute; their carriage lasts no more than 3 months. Persons who excrete infection after this term are chronic carriers. The number of acute bacillary carrier-convalescents rapidly decreases with each new week separating them from the disease. Thus, for example, according to Lingelsheim, the number of meningococcus carriers already after three weeks of recovery falls from 24.56% to 4.39%. In diphtheria carriers, according to Otto, liberation from carriage occurs: in 45% of cases after 3 days from the onset of the disease, after 10 days in 55%, after 3 weeks in 85%, after 4 weeks in 98%. In cholera carriers, according to Babes, 95% of carriers already on the 5th day of recovery are found to be free from carriage. Most researchers consider the average duration of cholera carriage to be two weeks, of typhoid and paratyphoid carriage 6-8 weeks. In an extremely small, however, not exactly established part of acute carriers, their carriage passes into a chronic form. The duration of chronic carriage is measured for individual infections from several months to tens of years. Thus, Selter, Kutscher, Gohn, and others cite cases of meningococcus carriage for up to 7 months and more; Wolfson, Prip, Löffler, Neisser - cases of chronic diphtheria carriage from 13 months to 14 years, Kulesh - a case of cholera carriage for 1 year, etc. Chronic carriage is particularly frequent and characteristic for typhoid fever and paratyphoids.

Marz compiled a summary of cases of typhoid carrier state reported in recent years. By duration, they were distributed as follows: from 1 to 10 years-16 people, from 11 to 20 years-10, from 21 to 30 years-4, from 31 to 40 years-5 and over 41 years-3 people. Priegge cites among the cases of chronic typhoid carrier state that he discovered a case where it lasted over 70 years. Among chronic carriers, periodicity of excretion of the infectious agent is often observed, alternating with periods of apparent well-being. These light periods, when the carrier does not contaminate the environment with their infection, can last from 16 days (Piras, in cholera) to 2-5 months (Ulenhuth) and even up to 1 year or more (Muller) in typhoid fever. Of course, such periodic excretors greatly complicate observation of them and present a huge danger to those around them. To form an idea of the role of bacillary carriers in the spread of infection, it is sufficient to cite some figures from the 1925 statistics of Möller (Möller), covering sources of infection during typhoid outbreaks in Germany: in 1912, out of every 100 cases of infection, the share of bacillary carriers was 31.4, in 1913 - 46.6, in 1914 - 31.4, in 1915 - 61.3, in 1916 - 43.5, etc. Chronic typhoid carriers play a particularly prominent role here, as is evident from Marz's literary summary. Some of them, over decades of their carrier state, infect hundreds of people. For example, in the Moselbach case, one potato peeler, over 12 years of her carrier state, managed to infect 230 people with typhoid fever, in the Woodward case, a milkman, over 18 years of carrier state, infected 135 people with typhoid fever, etc. Bacillary carriers of diphtheria present exceptional danger in terms of spreading infection. Their number in large cities can reach tens of thousands. For example, according to Park's calculation, based on 2% diphtheria carrier state among children, there should be about 20 thousand child carriers of diphtheria in New York alone. As the methodology and technique of research for bacillary carrier state improve, the numbers of detected carriers and their significance increase. But in this field, bacteriology has by no means said its last word. The existing methods and techniques available to modern bacteriology for establishing bacillary carrier state vary depending on the type of infection. They can be specified in the description of each infection separately. Measures to combat bacillary carrier state are divided into two groups: 1) measures aimed at curing carriers of the infectious agent present in their body, and 2) measures aimed at preventing carrier state. For treating the carrier of the infectious agent in their body, various bactericidal preparations as well as biological methods, for example, vaccination, introduction of antagonistic cultures, etc., and even surgical intervention (removal of the gallbladder in typhoid carrier state, etc.) have been and are being proposed; however, all these measures have so far proven ineffective. Preventive measures aimed at preventing bacillary carrier state are based on the same principles as protecting the population from the spread of an epidemic among them by the infectious patient himself. For the epidemiologist, the bacillary carrier is equivalent to the infectious patient. However, certain features inherent in bacillary carrier state as a latent form of infection, not coinciding with the clinical syndrome and sometimes lasting for tens of months and years, require a number of special measures. The most important of these are the following: 1. To prevent the spread of the epidemic in the incubation period of infection, all persons who had contact with the patient before their admission to the hospital must be isolated and observed for a period equal to the average incubation period of this infection. 2. Careful control upon discharge of recovered patients, as it is known that convalescents constitute the main group of carriers and most often develop the chronic form of carrier state. Therefore, a convalescent can be discharged only after two or even threefold bacteriological examination for carrier state, which gave consecutive negative results. These control examinations must, for example, for typhoid fever, be carried out starting from the seventh day after clinical recovery and repeated every new 7 days. 3. During the epidemic, as well as after its end, systematic examination of those population groups that are particularly predisposed to infections due to their domestic, professional, and other conditions is carried out. 4. In epidemics capable of spreading through water and food products, such as typhoid fever, paratyphoid, cholera, etc., careful detection of bacillary carriers involved in the supply of the population with drinking water and food products is required. Such bacillary carriers must be removed from work for the entire duration of their carrier state and allowed to return to work only after establishing their complete recovery from carrier state, which is confirmed by two or three consecutive negative results of their bacteriological examination. 5. Chronic bacillary carriers whose profession poses a danger of widespread infection, such as food handlers, water workers (typhoid fever), teachers (diphtheria), etc., must be completely removed from their professional work and considered as disabled persons in need of social security. To restore their social and material position, it is desirable to train them in a new profession where carrier state does not pose a public danger. Finally, all chronic bacillary carriers require not only systematic sanitary and bacteriological observation but also must be taught proper care for themselves, their household items, and their waste-in the direction of making these carriers as little dangerous as possible to those around them.