REMARKS ON THE DIFFERENTIAL

COUNT OF THE LEUCOCYTES IN MALARIAL AND OTHER

FEVERS OF INDIA.

By S. P. JAMES, m.b?

captain, I.M.S.,

On Special Duty.

Without wishing for a moment to minimise the value of the results of the different.# eu- cocvte counts which Captain Rogers has lately published in the Indian Medical Gazette I should like to refer briefly to the subject ot the differential count of the leucocytes in malaria, as this method of diagnosis has aroused consider- able interest since it was introduced into India by Drs. Stephens and Christophers

Captain Rofers says, in the Indian Medical Gazette for November, page 430 " I am so convinced of its great value (that .s the value of a differential count ot the leucocytes) as a simple and rapid method of diagnosis between malarial and other fevers of the tropics that I have come to regard the search for malarial para- sites at any rate in cases which have already been dosed with quinine, as almost a waste of time as a purely diagnostic measure in ordinary clinical work."

.

. This means that in ordinary clinical work Captain Rogers regards it almost as a waste of time to search for malarial parasites, because there is in the differential count of the leucocytes a more simple and rapid method of arriving at a diagnosis of malaria. It is not my object in

'12 THE INDIAN MEDICAL GAZETTE. [Jan. 1903.

these remarks to refer to the relative merits of

the different methods of diagnosis of malaria: it appears unnecessary indeed to do so, because

every one will agree that in a suspected case of malaria, even when quinine has been given, the

first thing to do is to search for parasites and lor /pigmented leucocytes, and that any other means of diagnosis is entirely of subordinate value to this. The finding of parasites or of pigmented 'leucocytes in a blood film makes the diagnosis ? of malaria a certainty, whereas the detection

of a change in the relative proportions of

the leucocytes at the best only indicates a

'probability. I desire rather to take exception to the words I have placed in italics in the

above extract from Captain Rogers' paper; for in my experience the making of an accurate

differential leucocyte count is a difficult and ex- ceedingly tedious matter, and for this reason

this method of diagnosis is very unlikely to be of much use in ordinary clinical work. In the first place, in order to obtain accurate results it is certainly necessary to count at least 500

leucocytes, and I believe I am correct in stating that Drs. Stephens and Christophers have pub- lished no cases in which they had not counted over 1,000 leucocytes. I have always admired the way in which either of these observers

could sit down at the microscope hour after

hour counting the leucocytes in a series of blood films from a single case ; and their doing so has always appeared t<> me to afford a very good example of "scientific method"?the method which teaches us to "give unqualified assent to no propositions but those the truth of which is

so clear and distinct that they cannot be doubted."* I admit that to examine and place under its correct name each of 1,000 leucocytes requires a strong effort of will, and the desire to stop after two or three hundred leucocytes have been enumerated is very great, but there is no rapid road, to accurate scientific results, and it is surely better to make one observation, the truth of which cannot be doubted than a hundred of which men will say, "can I rely on these results being absolutely true ?"

In view of the fact that the two observers mentioned above considered it necessary to make a count of 1,000 leucocytes in each case, I think we cannot consider results obtained from counts of only 250 leucocytes (which is the number stated by Captain Rogers to be sufficient), as

reliable. I note also that some of Captain Rogers' results are obtained from counts of only 100 leucocytes. We ma}' well ask why not 50 or even 25 ?

Assuming however that one is prepared to carefully examine at least 500 leucocytes, it becomes necessary to decide on the best form of stain. Undoubtedly the best stain for leuco-

cytes is Ehrlich's triple stain ( Ehrlich's Triacid-

losung f. neutroph. Granul, etc.), but this stain does not show up malarial parasites, and it is of course advisable to use a stain which will make any parasites tliat may be present, readily seen. Romanowsky's stain is therefore the best to use. I have not found that this stain has the disadvantages of which Captain Rogers speaks (viz., its difficult}' of preparation and its instability) and which have prevented him from recommending it. If made np in a single solution as recommended by Major Leishmann, r.a.M.c., in the British Medical Journal for

^September 21st, 1901, is exceedingly easy to

work and gives excellent results. The few diffi- culties that occur in preparing this single solu- tion stain are easilv overcome with a little

trouble, and 1 believe it can at the present time be obtained ready made even from some of our Indian chemists. It has the advantages of

rendering previous fixation of the blood films

unnecessary, and of keeping good for many months. The haematin stain recommended by Captain

Rogers is not entirely satisfactory for making leucocyte counts, though it shows up parasites well. It was used by Drs. Stephens and Chris- tophers in Africa, because at that time (1900) they had had little or no practice with

Romanowsky's stain. In the examination of the blood films the chief difficulty?and this is the only real difficulty in making differential counts ?will be found in deciding exactly what form of leucocyte is to be included under the term " large mononuclear." Captain Rogers' method is to enumerate as "large mononu- clears" all the sino-le nucleated leucocytes which are as large as, or larger than an average polynuclear cell. This appears to me to be an unsatisfactory way of diagnosing correctly this form of leucocj-te, for the size of none of the leucocytes is constant, and some of the

large lymphocytes are as large as a polynuclear cell. At any rate, by such a method, there will always be a certain number of "doubtful" forms, and I know from my own experience that if one is doubtful whether a particular leucocyte is a large mononuclear or not, the desire (which may of course be resisted) is to put such a leucocyte in the

"

large mononuclear "

column. How also about " transitional forms ?"

Does Captain Rogers class these with the

large mononuclears or not ? . Personally I think it is always better to enumerate the tran-

sitional forms in a separate column. Regard- ing this diagnosis of a large mononuclear

leucocyte I think the words in W. Myers' translation of the " Histology of the blood

"

by Ehrlich and Lazarus are important, and that it is better to be guided by them than to trust to the relative size of the different forms of leucocytes. Myers says,

" the laro-e mononuclear leucocytes are sharply distinguished from the lymphocytes. They are large cells about two to three times

sU Huxley, "Methods and Results."

Jan. 1903.J T^E SERUM TESTS IN DYSENTERY. 13"

the size of the red blood cell. They possess a

large oval nucleus as a rule eccentrically

situated, and a relatively abundant protoplasm which is free from granulations and stains very

faintl}* . Transitional forms are distin-

guished from these by the presence of a deeply

notched nucleus and by tne presence of scanty

granulations in the protoplasm. Undoubtedly a good method of impressing the chaiacters

of a large mononuclear leucocyte on one's

mind is ?

that recommended by Dr. C. H.

Melland in the British Medical Journal for

September 27th, 1902 ("The Leucocytes in

Malaria"), viz., to go carefully over a slide

containing pigmented leucocytes. Any mono-

nuclear ieucocj'te which contains pigment

granules will of course be a " large mononuclear,"

and its characters can be studied.

Lastly we have the difficulty that the relative

proportions of the different varieties of leuco-

cytes present in the blood of healthy 'natives of

India has not, so far as I am aware, been

worked out in any number ot cases. According to Dr. Christophers the proportion of large mononuclears in healthy natives ot Africa is

about 10 per cent. For children it may be much

higher than this. Some of Drs. Stephens and

Christophers' figures are as follow* :?

Large mononuclear. 1 13-2 1 2 12

3 24 v, Young children ; showing 4 24"5 |

110 parasites in the blood.

5 16-5 J 6 12 J

,

g_2 1 Adults ; passed the age at > which infection takes

o 13 j place.

I think that before we can deduce any inferences of value from this method of diagnosis of

malaria in India, it is certainly necessary to ob- tain figures from a number of films ot blood of

healthy natives of India at different ages. We

must remember that Dr. Stephens and Christo- phers' opinion that a" increase in the large mononuclear cells beyond 15 per cent, wasof great diagnostic value, referred only to Europeans?a fac? which has apparently been generally over-

looked. , ?

In conclusion, I may say that the results of

Captain Rogers' differential counts of leuco-

cvtes in seventeen cases ot malaiial cachexia in Calcutta (Indian Medical Gazette, No-

vember, page 427) materially from those of 80 cases of exactly tne same nature examined bv Ihs Stephens and Christophers in Calcutta last year; for whereas Captain Rogers shows a large mononuclear increase to be present m practically all his cases, Dr. Stephens and

Christophers distinctly state (referring to cases

classified as " malarial cachexia and enlarged

spleen" in the Calcutta hospitals): "We

examined over 80 of such cases, and in none

did we find parasites, or pigmented leucocytes, or any mononuclear leucocyte increase such as we have shown in earlier reports to be charac-

teristic of a recent infection .* It must therefore be left to others to deter-

mine which of these two series of observations

is correct, but sufficient has, I think, been said to justify my conclusion that the differential

count of the leucocytes is not by any means a

simple and rapid method of diagnosis which can be made use of in ordinary clinical work.

/

* " The malarial infection of native children." Reports to the Royal Society's Malaria committee, 3rd Series, 1900.

* Reports to the Malaria Committee of the Royal Society

6th Series, 1902, page 21.