GAURI BAZAZ-MALIK (From Maulana Azad Medical College and associated hospitals, New Delhi)

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1 TUBERCULOSIS IN MONKEYS : CAN IT BE A SOURCE OF INFECTION TO MAN? GAURI BAZAZ-MALIK (From Maulana Azad Medical College and associated hospitals, New Delhi) (PART II) It was observed that monkeys caught in the vicinity of Delhi, Mathura and other big cities gave a high percentage of positive tuberculin reaction as compared to those caught from the jungles away from these cities (Nair, Ray 1954). It was further shown that tuberculin positive monkeys when sacrificed revealed extensive fibrocaseous lesions of the lungs and other organs. Mycobacterium tuberculosis isolated from these lesions as well as from the bronchial secretions of the affected lungs were demonstrated to be similar and of human type. The organism had been reported to be infective to healthy tuberculin negative monkeys when inoculated subcutaneously and intraperitoneally (previous communication). The monkeys developed tuberculin hypersensitivity as well as lesions of various organs and organism recovered from the resultant lesion had the cultural, morpholgical and animal inoculation characteristic of the donor. From these observations it can be deduced that if the organisms isolated from a simian source is infective to monkeys under laboratory condition, such a possibility cannot be ruled out in nature when infected and normal animals come in close contact. Considering that the organisms infecting the monkey are of human type one wonders whether the infection has come from a human source. Benjamin (1954) has visualised this possibility. Steele (1966) has mentioned that monkeys and other primates are susceptible to human type of disease. That they frequently developed generalised disease and scumb, but during their illness they are active spreaders and may infect an entire troop in a short time. He also says that human beings can be infected from these animals in Zoo as well as from the animals kept in laboratories and as pets. Thus it is worthwhile to presume that monkey to man infection also is possible. However this problem can be solved by finding whether human type of mycobacterium tuberculosis isolated from a human source can cause disease in monkeys. If it does, it would be logical to think that human type of mycobacterium tuberculosis isolated from monkeys can also cause disease in man. The paper presents the observation made on the experiments carried out in this direction. Material and Methods Mycobacterium tuberculosis was cultured from the sputum of an untreated open case of bilateral pulmonary tuberculosis. Six weeks old colonies grown on Medler s medium were lifted, weighed and ground with sterile saline and sand. A uniform suspension of known volume and weight was prepared and used in these experiments. Animal inoculation of the bacterial suspension proved the organism to be of human type. Monkeys Tuberculin negative healthy North Indian monkeys (Mllulatta Mulatta) weighing 5-6 kgs. were used. They were kept on a standard diet in a well ventilated animal house for a month. The room and the cages were washed with dilute phenyl twice a day and food served after a wash at 8 A.M. and 6 P.M. The animal house was separate from the departmental animal house and was looked after by a separate staff. Therefore there was no contact with other experimental animal and possibility of cross infection was ruled out. Before starting the experiment, following investigations were done on the animals. (i) Weekly haemoglobin estimation, erythrocyte sedimentation rate, total and differential white cell count, (ii) Stool and Urine examination to exclude parasite and other infections, (iii) Tuberculin test repeated fortnightly. (iv) Weight record repeated fortnightly. (v) Radiograph of the chest. Experiment No. I Tuberculin negative male and female monkeys were inoculated with the bacterial suspension equivalent to 0.01 mg. of wet weight of bacterium/kilogram body weights of the monkey. Three routes of inoculation, i.e. intravenous, subcutaneous and intraperitoneal were used. The results are shown in table I. The group inoculated intravenously did not develope hypersensitivity to tuberculin even six weeks after inoculation. At autopsy of all the animals of this group revealed multiple

2 TUBERCULOSIS IN MONKEYS : CAN IT BE A SOURCE CF INFECTION TO MAN? TABLE I 13 A. INTRAVENOUS GROUP FORT NIGHTLY TUBERCULIN TEST MONKEY BEFORE 1 2 AFTER NOCULATION 1 D ALL DIED OF EXTENSIVE 2 D NECROTIC LESIONS 3 D WITH POOR CELLULAR RESPONSE B. SUBCUTANEOUS GROUP FORTNIGHTLY TUBERCULIN TEST MONKEY BEFORE AFTER s ALL ORGANS SHOWED s TUBERCULOUS LESION WITH S GOOD CELLULAR RESPONSE- C. INTRAPERITONEAL GROUP FORTNIGHTLY TUBERCULIN TEST MONKEY BEFORE 1 2 AFTER S ALL ORGANS SHOWED TUBERCULOUS S LESION WITH 600D CELLULAR RESPONSE

3 14 GAURI BAZAZ-MALTK TABLE II

4 TUBERCULOSIS IN MONKEYS : CAN IT BE A SOURCE OF INFECTION TO MAN? 15 focal necrotic lesions with a poor cellular response. On the other hand animals inoculated subcutaenously and intraperitoneally became tuberculin sensitive during third fortnight after inoculation. They continued to be tuberculin positive for six weeks when they were sacrificed or died. All had developed tubercular lesions of various organs and the lesions showed a good cellular response. Experiment No. II The strength of the inoculum in this experiment was reduced to mg wet weight of the organism/kilogram of body weight as it was felt that the previous high dose gave a poor chance of survival to the animal evidenced by death of some of them within six weeks due to often toxaemia and rapid loss of weight. The results of this experiment are shown in table II. In this experiment all animals developed tuberculin hypersensitivity during the second fortnight after inoculation and continued to be positive till they died or were sacrificed six to twenty four weeks after inoculation. At autopsy more than one organ showed tuberculous lesions with caseation and a good cellular response. Negative hypersensitivity response of the monkeys inoculated intravenously in experiment No. 1 may possibly be due to anergy these animals showed to a high dose of inoculum. Discussion Domestication of animals by man though of a mutual advantage has brought certain hazards in its wake. Tubercular infection of m\n from cattle is an illustration in point. In some countries it was found necessary to institute measures to control this disease in cattle to prevent the spread of the disease in man. But, in this country adequate steps have not yet been taken to deal with this aspect of the problem possibly because some investigators believe that tuberculosis of cattle in India is rare and infection of man by bovine bacillus is almost non-existent. However, recent research in the veterinary field have suggested that this position needs reviewing (Datta 1954). Tubercle bacilli isolated from cattle are generally bovine though occasionally human types have also been detected. Efforts of isolating tubercle bacilli from monkey have shown the isolated organism to be of human type (Jaswant Singh et al 1951) (Bazaz Malik earlier communication). Therefore it appears that simian tuberculosis may be of more vital importance than the bovine tuberculosis when control of tuberculosis in a community in this country is considered. One out of ten north Indian monkeys captured from big cities in north India have been reported to suffer from active tubercular lesion. Number of tuberculin reactors, and those having lesions have been reported to have increased rapidly with the period of captivity (Nair, Ray 1954). This suggests that the infection may spread in captivity from one animal to another. Krishnan (1936) reported spontaneous tuberculosis in a normal monkey coming in close contact with guinea pig infected with human type of tuberculosis. It has been reported that organisms isolated from monkey can cause disease in a normal healthy monkey (Previous communication). The present experiment shows that organism isolated from man can also cause disease in a normal healthy monkey. Therefore, it is logical to deduce that M. tuberculosis isolated from man and monkey also can cause disease in man. Man to man infection is an established fact but at present the infection from monkey to man is difficult to prove. However, if further survey is carried out it may be possible to establish a correlation between monkey and human tuberculosis, specially in the cities where they live in close proximity as an indirect evidence. Since the organism isolated from both sources has a similar, morphological, cultural and animal inoculative pattern, it would be rather unusual and surprising if such a correlation does not occur. It may be stressed here that the possibility of such happenings cannot be over looked while working on tuberculosis, specially for control of the diseases in the country. Live stock industry dealing with monkeys, in India is progressively developing and over crowding in animal sheds, stationary as well as mobile, is not an uncommon feature. Rapid spread of tuberculosis in these captive herds is a possibility, Further the spread of tuberculosis to man by ways other than sheer consumption of infected milk has to be seriously considered. Even in nature just given the right kind of environmental and other predisposing condition like overcrowding, malnourishment and unhealthy surroundings, infection is likely to spread from man to monkey and vice versa. Proof of such an eventuality is however still to come which neccesitates an extensive survey in cities where monkey and man live in a very close proximity. In such areas man to monkey infection has been said to occur (Benjamin 1954). Thus while thinking of preventive aspects of the disease in a community it is worthwhile to keep this possibility in view. These dangers have not been thought of for a long time and need to be

5 16 GAURI BAZAZ-MALIK studied seriously, specially in view of the present findings The investigation could profitably he undertaken jointly by dealers in live stock and local health bodies. The health authorities could take advantage of surveying monkeys caught by these agencies for export and scientific work in the country. Thus the material readily available for such a survey can be most economical. At the same time tuberculosis survey of the human population in the area from where the monkeys are caught can be utilized to study correlation if any between the human and simian tuberculosis. If man to monkey and monkey to man infection is possible in nature, the question that needs some thinking is in respect of the mode and route of infections. It is known that monkey has a cough reflex but monkey in captivity has not been observed to bring out sputum. Therefore infection cannot be though infected sputum possibility of droplet infection or infection through other formalities like saliva and other extretate cannot be excluded. In conclusion it can only be said that the problem is of great importance. Tuberculosis is a major public health problem in this country. The health survey and developmental committee estimated that in 1954 there were 2.6 million people suffering from active tuberculosis and mortality would be in the neighbourhood of 0.5 million every year (Pandit 1956). These no doubt are rough approximations and underestimates, nevertheless, they give an idea of the magnitude of the problem and a challenge to those dealing with the control of the disease. Though bovine, tuberculosis as the present thought is, is not considered to be an obstacle in the control of disease in India, enough light has been thrown on the simian source of infection to be taken as a serious handicap. In a country where large amount of money is being spent in the prevention of tuberculosis a survey on the lines suggested is worth considering. As stated earlier a co-ordination between the local Health authorities and those trading on monkeys would enable to undertake such a survey. At the same time highly tuberculin positive monkeys could be destroyed and thus a source of infection could be removed. Summary Human type of mycobacterium tuberculosis isolated from an untreated pulmonary tuberculosis patient has been shown to be infective to healthy tuberculin negative monkeys. In earlier communication, organisms isolated from tubercular lesions in a monkey was shown to be of human type. When the human type of mycobacterium tuberculosis is infective to monkey the possibility of an organism from the simian source infecting man is visualized. Further study in the field is considered necessary to prove such a hypothesis. An economical method for such a survey is suggested. ACKNOWLEDGEMENT The author is most grateful to Dr. A.P. Ray, Director, National Malaria Eradication Programme, New Delhi, Dr. (Miss) H B. Patil, ex-principal and head of the department of pathology, Lady Harding Medical College, New Delhi for their guidance, advise and constructive criticism. The investigation was supported by grants from the Indian Council of Medical Research, New Delhi, during REFERENCES 1. Bazaz-Malik Gauri, Earlier communication. 2. Benjamin. P.V. Editorial Ind. J. Tub. 1, 97, Datta 5., Preliminary report on incidence and prevalence of tuberculosis in cattle and domestic animal. Ind. J. Tub. 1, 81, Jaswant Singh; Balbir Singh; Gupta D.N; Nair C.P; Sataya Prakash. A note on tubercu losis in a laboratory monkey colony. Ind. J. Mal. 5, 239, Krishnan K.V. Tuberculosis in a laboratory animal Ind. J. Med. Res. 1936, 23, Nair C.P., Ray, A.P. Tuberculin test in diagnosis of tubsrculosis in Rhesus Monkeys Ind. J. Tuber., Pandit C.G., Research in tubsrculosis in India. Ind. J. Tub Steele J.H. working paper No. 17 IVth F.A.O. Far East Regional Conference on animal production and health, Ceyion, October 1966.