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Dear Sir:
We appreciate the comments of Dr. McKenzie. We are also interested in the other side of the coin; the effect of tuberculosis infection on the course of malaria. In our published series of experiments, there was a suggestion that peak parasitemia occurred slightly earlier in co-infected mice, although the gross pathologic appearance of the co-infected organs showed more hemozoin pigmentation suggesting a higher organ burden of parasites.1 In addition to the data cited by Dr. McKenzie in non-human primates,2,3 results of bacille Calmette-Guérin (BCG) vaccination experiments in mice have shown that BCG vaccination 30 days prior to lethal P. yoelii intraperitoneal challenge can favorably modulate the course of lethal rodent Plasmodium infection to survival.4,5 We have also seen increased survival in mice aerosol-infected with M. tuberculosis 14 days prior to lethal P. yoelii challenge (Manabe YC and others, unpublished data). Modulating the timing of co-infection and understanding its impact on the pathogenesis of both diseases may provide important insights into human infection given the high prevalence of tuberculosis in areas where malaria incidence is also high.
REFERENCES
- 1↑
Scott CP, Kumar N, Bishai WR, Manabe YC, 2004. Short report: modification of Mycobacterium tuberculosis infection by Plasmodium in the murine model. Am J Trop Med Hyg 70 :144–148.
- 2↑
Bazaz-Malik G, 1973. Increased resistance to malaria after Mycobacterium tuberculosis infection. Indian J Med Res 61 :1014–1024.
- 3↑
Singh JA, Ray P, Nair CP, 1956. Relationship of tuberculosis on the course and intensity of plasmodial infections in M. mulatta.Indian J Malariol 10 :3–10.
- 4↑
Matsumoto S, Yukitake H, Kanbara H, Yamada H, Kitamura A, Yamada T, 2000. Mycobacterium bovis bacillus Calmette-Guerin induces protective immunity against infection by Plasmodium yoelii at blood-stage depending on shifting immunity toward Th1 type and inducing protective IgG2a after the parasite infection. Vaccine 19 :779–787.
- 5↑
Matsumoto SH, Yukitake H, Kanbara H, Yamada T, 1999. Long-lasting protective immunity against rodent malaria parasite infection at the blood stage by recombinant BCG secreting merozoite surface protein-1. Vaccine 18 :832–834.