Ingestion of Plasmodium Falciparum Sporozoites during Transmission by Anopheline Mosquitoes

Magda S. Beiter Center for Vaccine Development, Department of Medicine, University of Maryland School of Medicine, Department of Immunology and Infectious Diseases, School of Hygiene and Public Health, The Johns Hopkins University, Baltimore, Maryland

Search for other papers by Magda S. Beiter in
Current site
Google Scholar
PubMed
Close
,
Jonathan R. Davis Center for Vaccine Development, Department of Medicine, University of Maryland School of Medicine, Department of Immunology and Infectious Diseases, School of Hygiene and Public Health, The Johns Hopkins University, Baltimore, Maryland

Search for other papers by Jonathan R. Davis in
Current site
Google Scholar
PubMed
Close
,
Charles B. Pumpuni Center for Vaccine Development, Department of Medicine, University of Maryland School of Medicine, Department of Immunology and Infectious Diseases, School of Hygiene and Public Health, The Johns Hopkins University, Baltimore, Maryland

Search for other papers by Charles B. Pumpuni in
Current site
Google Scholar
PubMed
Close
,
Bruce H. Noden Center for Vaccine Development, Department of Medicine, University of Maryland School of Medicine, Department of Immunology and Infectious Diseases, School of Hygiene and Public Health, The Johns Hopkins University, Baltimore, Maryland

Search for other papers by Bruce H. Noden in
Current site
Google Scholar
PubMed
Close
, and
John C. Beier Center for Vaccine Development, Department of Medicine, University of Maryland School of Medicine, Department of Immunology and Infectious Diseases, School of Hygiene and Public Health, The Johns Hopkins University, Baltimore, Maryland

Search for other papers by John C. Beier in
Current site
Google Scholar
PubMed
Close
Restricted access

We investigated the process of sporozoite transmission during blood feeding for Anopheles gambiae and An. stephensi experimentally infected with Plasmodium falciparum. When infective mosquitoes were fed 22–25 days postinfection on an anesthetized rat, sporozoites were detected in the midgut of 96.5% of 57 An. gambiae (geometric mean [GM] = 32.5, range 3–374) and in 96.2% of 26 An. stephensi (GM = 19.5, range 1–345). There were no significant differences between species either in salivary gland sporozoite loads or in the number of ingested sporozoites. There was a significant linear relationship between sporozoite loads and the numbers of ingested sporozoites for both An. gambiae (r = 0.38) and An. stephensi (r = 0.69). Subsequently, An. gambiae were tested for sporozoite transmission by allowing them to feed individually on a suspended capillary tube containing 10 µl of blood. A total of 83.3% of 18 infective mosquitoes transmitted a GM of 5.9 (range 1–36) sporozoites. The same mosquitoes contained a GM of 23.4 (range 2–165) ingested sporozoites. The number of ingested sporozoites was related to sporozoite loads (r = 0.42) but not to the number of sporozoites ejected into capillary tubes. Ingested sporozoites remained in the midgut up to 10 hr after feeding. The comparable numbers of sporozoites ingested by infective mosquitoes in both experiments indicates that the actual number of sporozoites transmitted to the vertebrate host during blood feeding is significantly reduced by the blood ingestion process. The detection of ingested sporozoites by simple methods that avoid contamination by mature oocyst or hemolymph sporozoites may facilitate determinations of the minimal numbers of sporozoites released during blood feeding either by naturally or experimentally infected mosquitoes.

Author Notes

Save