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 ::  Abstract
 ::  Introduction
 ::  Material And Methods
 ::  Results
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ARTICLE
Year : 1979  |  Volume : 25  |  Issue : 2  |  Page : 81-84

Wuchereria bancrofti microfilarial antigen in the diagnosis of human filariasis by skin test


1 Department of Surgery, Medical College, Miraj-416 410, India
2 Department of Surgery, Mahatma Gandhi Institute of Medical Sciences, Sewagram, Wardha-442102, India

Correspondence Address:
M Subrahmanyam
Department of Surgery, Medical College, Miraj-416 410
India
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Source of Support: None, Conflict of Interest: None


PMID: 387950

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 :: Abstract 

Wuchereria bancrofti microfilarial antigen was investigated in skin test on: (1) Microfilaria carriers, (2) Amicrofilaraemic cases from endemic villages with and without intestinal helminths, (3) Cases having apparent symptoms and signs of filariasis. The anti­gen reacted with specificity in cases having apparent symptoms and signs of filariasis. In microfilaria carriers and amicrofilaraemic individuals from endemic areas no reaction was seen. The diag­nostic value o f W. bancrofti microflarial antigen in chronic cases has been discussed.



How to cite this article:
Subrahmanyam M, Belokar W K. Wuchereria bancrofti microfilarial antigen in the diagnosis of human filariasis by skin test. J Postgrad Med 1979;25:81-4

How to cite this URL:
Subrahmanyam M, Belokar W K. Wuchereria bancrofti microfilarial antigen in the diagnosis of human filariasis by skin test. J Postgrad Med [serial online] 1979 [cited 2020 Oct 24];25:81-4. Available from: https://www.jpgmonline.com/text.asp?1979/25/2/81/42113



 :: Introduction Top


Except apparent elephantiasis the diag­nosis of filariasis in amicrofilaraemic cases remains a clinical assumption. Espe­cially this is true of early hydroceles, epididymo-orchitis, lymphangitis or lymph varix when microfilariae can­not be demonstrated in the peri­pheral smear at night. Development of a diagnostic test which would be sensi­tive and easy to perform is of value in these cases. This paper reports the re­sults of a skin test carried out with W. bancrofti microfilarial antigen in patients attending the surgical out patient department of our unit at the Mahatma Gandhi Institute of Medical Sciences, Sewagram, Wardha which is an endemic zone for filariasis.


 :: Material And Methods Top


The antigen was prepared from W. bancrofti microfilaria collected from microfilaria carriers. These organisms were isolated by Dextraven method by using Dextrose saline and dextraven. The isolated worms were then homogenised in normal saline, The homogenate was sonicated. Proteins were estimated by the method of Lowry et al [5] and the strength adjusted to 80 µg/ml by the addition of required amount of normal saline. 1:10,000 Merthiolate was added as a preservative and the antigen solution was stored in cold.

The test was performed on the follow­ing groups of patients:

Group I:- Microfilaria Carriers.

(Patients in whom micro­filaria were demonstrated in the peripheral smear. This also included carriers from villages after mass survey).

Group II:- Amicrofilaraemic Cases. (Those who were not suf­fering from filariasis but attended our hospital for other diseases.

This group was further subdivided into two:

(a) With helminth posi­tive.

(b) With helminth nega­tive.

Group III:- Chronic cases.

(With apparent signs and symptoms of filariasis).

The Antigenic Test: This was perform­ed by injecting 0.05 ml (4 µg of protein) of the antigen solution intradermally on the volar surface of an arm and an equal amount of merthiolated saline on the opposite forearm. The original wheals (due to antigen and saline) were encircl­ed by a ball pen. The results were read after 15 minutes. The raised indurated areas were also marked with a ball pen. The surrounding erythema was not in­cluded in the measurement. The wheal imprints just after injecting the antigen and fifteen minutes later were taken on a butter paper moistened with alcohol. The areas of wheals were determined with graph paper and expressed as mm. [2]


 :: Results Top


The results of the skin test with W. bancrofti microfilarial antigen on various groups of persons have been summarised in [Table 1]. For the purpose of classification doubling of the wheal area after 15 minutes was taken as the posi­tive skin test. The ratio of the final wheal area to the initial is referred to as the reaction ratio in the sequel. Merthiolated saline medium did not cause any increase in the wheal area 15 minutes after injec­tion. The reaction ratio was less than 1.2 for all non-reactors.

The antigen reacted specifically in chronic cases whereas in microfilaria car­riers and amicrofilaraemic cases the reac­tion was negative except in two cases in group II (B). The reaction ratio also was 3.52 ± 0.032 in chronic cases (Group III), whereas in all other groups it was less than 2.


 :: Discussion Top


Diagnosis of Filariasis due to W. ban­crofti and Brugia malayi is dependant on the detection of microfilariae at night.

Hence except in apparent elephantiasis the diagnosis of the disease in amicrofi­laraemic cases remains a clinical assump­tion. This is specially true of hydroceles, epididymo-orchitis, cellulitis of the upper and lower limbs and lymphangitis which are commonly seen in this area.

It is recognised that microfilariae may not be demonstrated in the blood of hu­man cases where any of the following conditions exist:

(1) In cases of single sex infection.

(2) Where living adult males and females are not located in the same lymph channel or gland.

(3) Where there is occlusion of the lymph channels inhabited by fer­tile female so that microfilariae may not reach the blood.

(4) And when adult filariae are dead already.

In view of these, lymph gland biopsy or the use of antigen by skin test or sero­logical tests to demonstrate the labora­tory evidence of infection, becomes im­perative as an adjuvant in doubtful clini­cal entities. The skin test is easy to per­form on mass scale, less laborious and time consuming, and the greatest advan­tage is that the patients are not disturb­ed during the night and less sophistica­tion is required in performing the test.

Filarial worms like other living helminths are known to stimulate anti­body production. Antigens from various filarial worms i.e. Set aria cervi, [6] W. equinaa Litomosoides carnii were tried to detect human filariasis by skin test but these were found to give equivocal results and the antigens were mostly group spe­cific. The highly purified skin test antigen developed by Sawada et al [7],[8] from the dog heart worm "Dirofilaria immitis" is claimed to be specific. Chandra et al [2] tried the antigen from the infective larvae of W. bancrofti in mass survey, and found that the homologus antigen was species specific and was not helpful in amicrofila­raemic doubtful cases. The modification of the skin test by a course of diethyl car­bamazine has been discussed by Gonra­ler [4] and. Chandra et al [2] .

In cases of filariasis with apparent signs and symptoms like hydroceles or lymph varix the post operative lymphoedema or lymph scrotum has been significant. [1] A pre-operative aetiological diagnosis of these lesions may have a significance though it is conjuctural at this stage.

Some false negatives in this group are due to use of diethyl carbamazine in those patients varying from 2 years to 6 months prior to conducting this test. The antigen derived from W. bancrofti larvae on the other hand gave positive test with microfilaria carriers, chronic cases and persons from endemic areas. [2] The W, bancrofti antigen on the other hand gave positive reaction in chronic cases, where as in the carriers the reaction was significantly negative as was noted in our series. In order to pin point the false positive reactions due to helminths, twelve helminth positive cases were sub­jected to the test, however none gave the positive reaction. Thus in chronic cases the antigen reacted with specificity. This test is valuable in diagnosing doubtful cases.

However this test has to be performed with purified antigen and with varied protein concentrations.


 :: Acknowledgements Top


We are thankful to Dr. M. L. Sharma, Principal and Medical Superintendent and to Dr. Sushila Nayar, Director, Mahatma Gandhi Institute of Medical Sciences for their kind permission to publish this paper.

Our thanks are due to Dr. S. N. Girni­kar, of the Filarial Research-cum-Train­ing Centre, Wardha for his constructive criticism.

Thanks are due to Shri Shanmukha Rao for his secretarial assistance.

 
 :: References Top

1.Belokar, W. K., Narang, R., Subrahman­yam, M, and Shrotrey, M. K.: A Clini­cal study of scrotal hydrocele. Clinical Reporter, 1: 277-282, 1977.  Back to cited text no. 1    
2.Chandra, R., Govila, P., Chandra, S. Katiyar, J. C., and Sen, A. B.: Wuche­reria bancrofti larval antigen in the diag­nosis of human filariasis by skin test. Ind. J. Med. Res., 62: 1017-1024, 1974.  Back to cited text no. 2    
3.Goodman, A. A., Weinberger, E. M., Lippincott, S. W. ,Marble, A. and Wright, W. H.: Studies of filariasis in soldiers evacuated from the South Pacific. Ann. Intern, Med., 23: 823-830, 1945.  Back to cited text no. 3    
4.Gonzaler, 1953: As quoted by Chandra et al, 1974.  Back to cited text no. 4    
5.Lowry, O. H., Rosefrongh, N. J . , Farr, A. L. and Randall, R. J.: Protein mea­surement with the Follin phenol reagent. J. Biol. Chem.. 193: 265-275, 1951.  Back to cited text no. 5    
6.Ridley, D. S. and Stoll, G. J.: The skin test in filariasis using Setaria cervi. J Trop. Med. Hyg., 64: 297-299, 1961.  Back to cited text no. 6    
7.Sawada, T., Takei. K., Katamine. D. and Yoshimura, J.: Immunological studies on filariasis III. Isolation and purification of antigen for intradermal skin test. Jap. J. Expt, Med., 35: 125-132, 1965.  Back to cited text no. 7    
8.Sawada, T., Sato, S. and Matsuyama, S.: Intradermal skin test with antigen. FST (FSCOI) on individuals in endemic area. Jap. J. Expt. Med. 38: 40.5-414. 1968.  Back to cited text no. 8    



 
 
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