The intradermal test using as antigen a 1 per cent saline extract of Dirofilaria immitis powder was performed in Singapore on 69 persons with eosinophilic lung, 32 with mild eosinophilia, 49 with filariasis, 75 normal Asians, and 66 normal Britishers. The test was positive in 100 per cent of the cases of eosinophilic lung, 73.5 per cent of the filariasis group, 59.4 per cent of cases of mild eosinophilia, 53.3 per cent of normal Asians, and 4.5 per cent of the Britishers. The filarial complement fixation test using a 1 per cent alcoholic extract of the same antigen gave a positive rate of 100 per cent in the eosinophilic lung group, whereas only 24.5 per cent of the filariasis patients gave a positive reaction. Skin sensitivity to D. immitis antigen persisted in the cases of eosinophilic lung even when the previously positive serologic reactions had become negative following treatment with diethylcarbamazine. Therefore, the intradermal test cannot be useful in the diagnosis of either filariasis or eosinophilic lung in Singapore. In view of the skin sensitivity to a filarial antigen demonstrated in patients suffering from eosinophilic lung, the etiologic possibility of an infection by a species of filarial worm found normally in nonhuman hosts is discussed.
In view of the risk of introduction of yellow fever into South-East Asia, comparative studies have been made of yellow fever vaccination in Malayan volunteers with a high prevalence of antibody to related viruses and in volunteers without related antibody. In a previous paper the neutralizing antibody responses of these volunteers were reported. The present paper describes the haemagglutinin-inhibiting (HI) antibody responses of the same groups of volunteers and discusses the relationship of these responses to the neutralizing antibody responses.The HI responses to yellow fever following vaccination closely paralleled the neutralizing antibody responses whether vaccination was subcutaneous or by multiple puncture. Volunteers with a high level of YF HI antibody due to infection with other group B viruses were found to be less likely to show a significant YF HI response than those without antibody. 90% of HI responses could be detected by the 21st day after vaccination.As with neutralizing antibody responses, volunteers given vaccine doses of 50-500 mouse intracerebral LD(50) subcutaneously gave greater responses than those given higher doses.
Saline extracts of ether-treated Dirofilaria immitis, Ascaris suum, and Ancylostoma spp. were used in indirect hemagglutination tests of serum from 164 patients with a diagnosis of eosinophilic lung and 114 persons with other diseases or no disease (blood donors). In the first group, positive reactions with one, two or all three antigens were obtained in 89 percent of cases and the titers, at medium or high levels in 77 percent, decreased after treatment with diethylcarbamazine. In the other group, antibodies were demonstrable in the serum of only 22 percent of cases and titers usually were low. These observations indicate the presence of several antigen-antibody systems, some of which appear to be specific. With extracts of Dirofilaria the indirect hemagglutination and the complement-fixation tests were similar in sensitivity and specificity, but the results from neither test appeared to indicate infection with a specific worm.