从热带地区返回的33名旅客,经寄生虫学检验确诊有疟疾初次感染,他们的血清在间接免疫荧光试验中呈现出种特异反应。感染间日疟原虫和卵形疟原虫的病人血清与P.fieldi(猴疟)显示出明显的交叉反应,而在恶性疟原虫感染的病例中则未观察到与P.fieldi有交叉。曾到过热带地区至少有2次疟疾发作史的16名旅客血清的种特异反应不明显,但仍然可以辨认出一定程度的特异性。来自流行区的15名血内带有原虫的居民血清,则没有出现这种现象。经有效的 Thirty-three travelers returning from the tropics were initially diagnosed with parasites by malaria tests and their sera showed a specific response to indirect immunofluorescence. Serum from patients infected with P. vivax and P. ovale showed significant cross-reactivity with P.fieldi (P. malacca), whereas P. falciparum did not cross with P.fieldi in P. falciparum-infected cases. Sixteen passenger sera, who had had at least two malaria episodes over the tropics, had an unusually specific sero-response but still some degree of specificity was still identifiable. This phenomenon did not occur in 15 blood serums carrying protozoa from the endemic area. Effective