Leptospirin — An Intradermic Test for the Diagnosis of Leptospirosis

In the State of Bahia (Brazil) the leptospirin produced in Germany for experimental use by the Institute for Veterinary Medicine, Federal Health Office, Berlin, was administered to humans and animals in order to diagnose leptospirosis in collaboration with this Institute. The results were compared with the microscopic agglutination reaction. The total number of test persons or animals was 268; this group included 81 human patients, 60 heads of cattle, 50 goats, 40 pigs, 25 horses, and 12 dogs. All were tested serologically and simultaneously the intracutaneous test was carried out. This test was positive when the erythema formed had a diameter of more than 9 mm. The evaluation took place 8 to 10 h and 24 h after the injection of leptospirin.

• 1.

  52 humans reacted serologically; out of this group 44 were positive in the leptospirin test. The allergy test was also negative in the 29 serologically negative patients.

• 2.

  Out of the 21 heads of cattle with a positive agglutination test 7 reacted to leptospirin whereas 39 animals which did not react serologically were also negative in the skin test.

• 3.

  Although 10 goats out of 50 reacted serologically, all were negative in the intracutaneous test.

• 4.

  9 out of 40 pigs reacted serologically; however, 8 reacted only to apathogenic leptospires (L. patoc, L. rufino, L.andamana). Out of these 9 animals 4 were positive in the intracutaneous test; among them the pig which reacted serologically to L. autumnalis. Out of 31 serologically negative pigs 2 were allergologically positive.

• 5.

  Out of 21 serologically positive horses 15 exhibited an erythema which was considered positive in the skin test. 4 serologically negative animals also were negative in the intracutaneous test.

• 6.

  Out of 6 serologically positive dogs, 4 reacted to leptospirin. 6 that had not reacted serologically were all negative in the intracutaneous test.

A comparison of the serological and allergological findings judged by the serological standard showed that out of all cases tested, 0.7% had at the same time a serologically negative and allergologically positive reaction and 16.8% had a serologically positive and allergologically negative reaction.

In some cases, the administration of leptospirin caused the formation of antibodies which could only be detected in low dilutions and usually disappeared after 6–8 weeks.

In humans, pigs, and horses the leptospirin also showed positive reactions which serologically could be attributed only to biflexa leptospires. Serotypes not contained in the leptospirin were accounted for to a varying degree in the individual animal species. These reactions and the results of other studies carried out in pig stocks have been the basis for studies performed at the Institute for Veterinary Medicine. These studies are expected to contribute to an improvement of the sensitivity of the leptospirin.