 |
|
||||
|
|||||
| About | Latest Articles | Back-Issues | Articles
|
Search | Instructions | Online Submission | Subscribe | Etcetera | Contact |
| |||||||||||||||||||||
|
Gosumecs' contribution to Helminthiasis SN KothareSt. John's Medical College, Bangalore, India
Correspondence Address: Source of Support: None, Conflict of Interest: None PMID: 1032824
I am delighted to have been invited to deliver the "Dr. R. G. Dhayagude Memorial Oration." This gives me the opportunity to pay humble tribute to a great pathologist, a great teacher and a great man, as also to my Alma Mater by participating in this year's celebrations. I am grateful to the Dean and members of the Dr. R. G. Dhayagude Memorial Committee for this unique honour and I hope that with this effort I shall prove worthy. To many of you here, Dr. R. G. Dhayagude is a legendary figure. Though the Professor of Pathology at these institutions, he was primarily interested in the subject of Microbiology and Parasitology. I shall always be deeply grateful to him for giving me an opportunity to work under him. For the purpose of this lecture, I define "Gosumec" as one who has been either a student of Seth G. S. Medical College and the K.E.M. Hospital or who is, or has been, a member of the Staff of these institutions. In Helminthiasis, I propose to include diseases and associated lesions produced by helminths. It must be realised that this is an attempt to cover contributions which I consider relevant to the subject. It is likely that due to oversight some of the contributions by Gosumecs may not have been cited. To these Gosumecs, I offer my sincere apologies. I think it serves a useful purpose to recall an incident that occurred way back in 1940 when I was an acting Resident Pathologist. Reporting on one of the autopsies, I described histological features of a peculiar lesion in the spleen as a localised proliferation of the reticulo-endothelial cells. As was the practice, all histopathology slides were shown to the Professor for confirmation. To his query regarding the diagnosis of the lesion, I promptly replied "Reticuloendothelial hyperplasia". Not being satisfied with this, he proceeded to explain at great length that there was not only R.E. cell hyperplasia but there were also a few eosinophils, and lastly showed me the all important structure, - cut segments of microfilariae. He further admonished me for not keeping in touch with studies that were being conducted in the department as Dr. Arvin and he were jointly engaged in a study of such lesions. The outcome of the study undertaken by Dhayagude and Amin [7] was published in the year 1°42 and was entitled "Microfilarial Granulomata of the Spleen". The microfilariae were identified as those of W. bancrofti. Such microfilariae were also detected by them in capillaries of the myocardium, lungs, glomeruli, liver, brain, testis and epididymis without any reaction in these tissues. Dr. Dhayagude had realised that without the support of experimental proof, the microfilarial etiology of this lesion would be a mere conjecture. He, therefore, set about in search of a suitable laboratory animal. He learnt from his veterinary colleagues that dogs suffer from infestations with filarial worms - Dirofilaria immitis and Diroflaria repents, He thus launched on a survey of stray dogs for filarial infestations. Dr. Dhayagude [8] reported this survey in an article entitled "Dirofalaria repens infestation of dogs". The prevalence of filarial infestation in dogs was nearly 5 per cent. He also demonstrated that, like D. immitis, there was periodicity of microfilariae in the peripheral blood of dogs infested with this parasite. The next logical step was an attempt to produce the nodule in the spleen of nonfilarial dogs by repeated transfusions with filarial positive blood. Some of the positive dogs with blood showing microfilariae were sacrificed in order to ascertain whether they also harboured the adult living parasite. A thorough search of such animals proved valuable in that the adult parasite was recovered from the subcutaneous tissue. None of the filarial dogs showed any pathological lesion on gross or microscopic examination. These experiments were eventually given up as similar nodules could not be produced in recepient dogs. Perhaps the reticuloendothelial system in man and dog respond in a different manner to microfilariae. Joshi, Udwadia and Gadgil [10] in 1969 in their study on "Etiology of Tropical Eosinophilia" have demonstrated microfilariae of Brugia malayi species in the alveoli and blood vessels in a lung biopsy of one case. The exact role of such microfilariae in the lung in the causation of Tropical Eosinophilia has been the subject of controversy. It has been stated that such larvae are incidental particularly in endemic areas and/or such microfilariae belong to species infecting lower animals and man is an accidental host without any consequence. In 8 other cases they observed eosinophilic structures in microscopic granulomata which could be disintegrating parasites probably other than microfilariae. Credit for another contribution, on this subject goes to Deodhar and Deshpande [4] for their interesting autopsy report on "Acute Microfilarial Encephalopathy" in 1871. This, I believe, is the third case reported in Indian literature. This was a patient admitted in a comatose condition and on autopsy showed microfilariae in cerebral capillaries and an associated microfilarial granuloma in the spleen. They have stressed the role of obstruction to the blood flow in the cerebral capillaries by the parasite as a probable factor in the pathogenesis of encephalopathy. Guinea worms producing lesions in various sites have been reported but mention must be made of a case report of "Constrictive Pericarditis resulting front Drancunculosis" by Kinare, Parulkar and Sen [11] in 1962, which is indeed very rare and perhaps the first in the world literature. Let me now pass on to another common Nematode, the Ascaris lumbricoides. This parasite is generally considered innocuous, except in large numbers when it could cause intestinal obstruction entailing surgical intervention. Purandare and Deoras [14] have, in their autopsy study of 162 cases of "Liver Abscess", encountered 2 cases due to this parasite. Recently I understand that there have been four autopsies at this hospital with this worm in the common bile duct and pancreatic duct associated with pancreatitis. The exact role of these worms in producing lesions remains problematic except on the basis of mechanical obstruction and resultant complications. Another Nematode of importance is the Ankylostome - the prevalent species in our country being A. duodenale and N. americanus. Hook worm infestation has been listed amongst the factors causing Microcytic Hypochromic Anaemia in tropical countries. Daftary and Bhende [1] in 1556, by a careful study of the worm load and the associated anaemia confirmed that the total worm population and the severity of the anaemia were not necessarily proportional and that besides the parasite, multiple factors were involved in the pathogenesis of anaemia, thus exonerating to a certain extent this much maligned worm. Diseases due to Trematodes are very rare in our country. Schistosomiasis, though rare, is not unknown in India, contrary to what is published even in recent books on Parasitology by Indian authors. In 1949, deSa and Monteiro [6] published the first case of "Urinary Bladder Schistosomiasis" from the K.E.M. Hospital. This patient had never left the shores of India and was a resident of a village near Ratnagiri. In the lesion "The Papillomata did not have the delicate waving fronds of the true neoplasm. On the contrary, the processes on the papillomata were coarse and stunted and had a curiously granular greyish-yellow appearance". Concluding the report they observed, "The possibility of an endemic focus of Schistosomiasis cannot be absolutely ruled out unless a survey of the population in the village concerned is carried out". Taking this cue, our colleagues from the Grant Medical College made a survey and established the endemic focus at Gimvi. A similar case has also been reported by Potnis and Mudbhatkal [13] in 1967. Manohar and his Associates" have published in 1966 a report entitled "Fasciolopsiasis in Bombay" focussing the attention on endemic foci in the northern parts of Greater Bombay. The species identified was F. buskii. This was a study of 124 patients, adults and children. Two prominent signs seen were the large doughy abdomen and anaemia with puffy face which the authors consider characteristic of infestation with this parasite. Cestodes belonging to the phylum Platyhelminthes need special mention because various species of this family are known to produce protean clinical manifestations. It is a well known fact that eating inadequately cooked beef or pork with Cysticerci is responsible for tape worm infestation in man. However, between the two infestations, one with Taenia solium, popularly known as the pork, tape worm, is more dangerous due to the fact that man can also serve as an intermediate host with the formation of Cysticercus cellulosae in various tissues resulting in bizarre clinical manifestations. The first proven case of "Generalised Cysticercosis" with neurological manifestations was encountered in the K.E.M. Hospital in 1951 and published by DeSa and Kothare [5] in 1952. Prior to this only two such cases were published from the Grant Medical College. Vakil and Sirsat [22] in 1965 published a report of six cases of "Cysticercosis in Man" from the Tata Memorial Hospital. In the majority, histopathology showed inflammatory reaction consisting of polymorphs, lymphocytes, plasma cells, histiocytes and foreign body giant cells. I shall again refer to these findings when discussing our observations on the same subject. Recently Salgaucar and Watcha [15] in 1574 reported a case of "Muscular Hypertrophy due to Cysticercosis". In this boy, hypertrophy of the following muscles was seen-erector spinae, deltoids, masseters, bisceps, etc. Biopsy showed well localised Cysticerci in muscle tissue with a fibrous wall and inflammatory cells were noted beyond this wall. According to the authors, this is the 11th case of muscular hypertrophy reported from India, associated with Cysticercosis. At St. John's Medical College we have also come across such lesions in autopsy and surgical biopsies. In our autopsy report [18] published in 1569, we encountered hydrocephalus due to the presence of a free Cysticercus cellulosae lying in the left lateral ventricle. Such cysts are known to cause hydrocephalus by obstructing the Foramina of Luschka More Details and Magendie. The left foramen of Luschka was found obliterated in our case. Our interest in the subject was again aroused when recently we came across a spate of Cysticercosis in our surgical biopsies. From our material it is interesting to note that the right side was involved more often than the left, and females more frequently than males. Whether this predilection for the right has any relation to right handedness resulting in localisation of such cysts to the more active muscles is a point for consideration. At this stage it is worth recalling that in Salgaucar and Watcha's case [15] the more active muscles are involved. In pigs, such Cysticerci are frequently seen in muscles of the snout, the tongue, the harmstrings, and the shoulder girdle-muscles which are most active. The slight preponderance of the female sex in our series may be attributed to their desire to get rid of unsightly lumps for cosmetic purposes. The possibility of predisposition of the female sex due to their domestic chores such as sweeping the floor and accidentally swallowing the dust charged with the ova cannot be excluded. Such a mode of transmission would also explain the occurrence of such cysts in strict vegetarians and others who are precluded from consuming pork on religious grounds. [19] Subsequent to this, we [20] have been attempting to study the evolution of the lesion with a view to ascertain whether (a) the varied inflammatory response was due to the type of tissue involved and (b) the same was necessarily preceeded by death of the parasite. It was therefore, considered advisable to extend this study to cysts from as many different tissues as possible. The request for such material was readily acceded to by Dr. D. H. Deshpande, your Professor of Neuropathology and Dr. P. M. Chaphekar. Professor of Pathology, Lokmanya Tilak Municipal Medical College, Sion. From the biopsy and autopsy material it appeared that the inflammatory reaction or the host tissue responses were not modified by the tissue involved. The spectrum of cellular response consisted of lymphocytes, plasma cells, histiocytes, epithelioid cells, foreign body giant cells, eosinophils and neutrophils as late contributors. By a comparative study on porcine tissue with Cysticerci, it was possible to determine the source of epithelioid cells which we think is the endothelial cell lining of the vascular channel in which the bladder cyst is impacted and is growing. The study of measly pork also afforded us with Cysticerci which are usually alive. In such cysts the presence of oval or spherical structures in the larval tissue beneath its germinal layer was a striking feature. On application of histochemical methods it was evident that these structures were composed of glycogen, lipids and calcium. Identical structures were also seen in human Cysticerci but in varying number. It was, therefore, suspected that they were products of metabolism of the larva and could be an index of the living status of the parasite. Fortunately the retro-retinal larva in one of our cases, which was seen moving on opthalmoscopy provided us with the unequivocal evidence. Such structures were numerous in this larva and without much inflammatory reaction around. We also believe that the lesion passes through various stages, in many instances, before the parasite dies. For the purpose of brevity these are described as four arbitrary stages with an occasional "skip" phenomenon. [20] The study of Cysticerci in various stages of development. particularly from surgical biopsies makes us believe that the appearance of clinical manifestations and the death of the parasite are related. The clinical manifestations such as swelling and pain appear with the death of the parasite, as confirmed histologically by the presence of polymorphonuclears, and an acute inflammatory response, which prompted the patient to seek medical attention. It is, therefore, reasonable to believe that clinical symptoms such as epilepsy, etc. appear on the death of the parasite and with the appearance of inflammatory reaction in internal organs, as stated, in textbooks on Internal Medicine. Another interesting condition in our country is Hydatidosis, which is due to ingestion of the ova of E. granulosus - the dog tape worm. The normal habitat of the adult worm is in the intestine of the dog. Other animals including man get infected through food contaminated with the ova of this worm, which eventually are transformed into Hydatid cysts. Hydatid cysts have been reported from various tissues and organs. Kanvinde and his associated [17] reviewing their material of 50 cases have, in 1959, reported a single case involving the heart. The cyst was situated in the myocardium near the apex. The authors claim that this is the first instance of involvement of the cardiac muscle reported from India. We have also been interested in this subject but with a different slant. Our objective has been towards a better understanding of the host tissue response to the presence of such cysts. We have on our files, 12 patients of Hydatid disease with organ involvement. One of these patients with a mesenteric cyst was operated upon more than once and eventually provided us with a specimen of the greater omentum with 42 cysts of various sizes. In this particular specimen we got the necessary material to study tissue responses at various stages of the growth of the cyst. In our studies on Hydatidosis, [21] we have observed four distinct layers in these cysts; the innermost being the germinal layer, next the laminated, the third uniformly pink or red, at places hyaline and at others finely granular in the H & E, and the outermost collagenous layer with cellular infiltrate consisting of lymphocytes, macrophages, epitheliod cells and giant cells. On application of various histochemical methods we were surprised to note that the acid phosphatase activity was detected in all layers but in varying amounts. The third layer which in histological preparations generally appeared homogenous with H & E stain and on gross examination as cheesy material, was moderately positive for acid phosphatase. The innermost germinal and the adjacent layer showed a large amount of acid phosphatase activity. In the outer collagenous layer, isolated cells with oval or spheroidal nuclei showed this enzyme activity and so did the macrophages abutting against the third zone referred to above. We are not quite sure whether this enzyme is produced by macrophages and permeates through towards the germinal layer of the parasite or the process is, in fact, the reverse direction. We are inclined to believe that the isolated large cells in the outermost layer are macrophages, rich in acid phosphatase as demonstrated by Dannenberg et al [2],[3] in 1968. They have also shown that epithelioid cells have a high acid phosphatase content. Jones-Williams et al [9] in 1970, and Papadimitriou and Spector [12] in 1971 have suggested that epithelioid cells are modified macrophages and among other enzymes produce acid phosphatase for "ex port". The acid phosphatase in zone may be due to the enzyme secreted by macrophages and epithelioid cells of zone four. Whether this enzyme has any deleterious effect on the growth of the parasite thus aiding in the ultimate destruction of the larva is not yet clear. Surprisingly, we noticed a marked similarity in the cellular response of Cysticercus cellulosae and Hydatid cysts. It, was, therefore, pertinent to enquire into the role of immunity in the evolution of these lesions. Is it the humoral or cellular immunity which plays a more important role in localisation and eventual death of the larva? The study of multiple cysts in the same individual with varied cellular response. was not consistent with humoral immunity. Secondly, the available laboratory tests employing humoral antibodies are not reliable as diagnostic tests. The intradermal hypersensitivity test with nonspecific taenia antigens is a point in favour of cellular immunity. The poor cellular response in the earlier phases could as well be due to the inability of the host's immunological apparatus to recognise the larva as an unwanted guest. However, the appearance of lymphocytes and plasma cells in later stages could be a reflection of cell mediated immunity and its consequent build up for the final assault. This observation has prompted us to study in depth the role of cellular immunity in the development of such lesions, which is being pursued in our laboratory. Before concluding, I would like to impress upon the young that patients in our General Hospitals are vertiable museums of Parasitology, Protozoology, and Helminthology. It is upto us to look into them intelligently and discover the treasure that is denied to workers in advanced countries.
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
|||||||
