Contribution to Malaria Transmission of Symptomatic and Asymptomatic Parasite Carriers in Cambodia

• Published in: The Journal of infectious diseases 2018-04, Vol.217 (10), p.1561-1568
• Main Authors: Vantaux, Amélie, Samreth, Reingsey, Piv, Eakpor, Khim, Nimol, Kim, Saorin, Berne, Laura, Chy, Sophy, Lek, Dysoley, Siv, Sovannaroth, Taylor, Walter R, Ménard, Didier
• Format: Article
• Language: English
• Subjects: Adult; Animals; Anopheles; Cambodia; Child; Female; Human health and pathology; Humans; Infectious diseases; Life Sciences; Malaria, Falciparum; Malaria, Vivax; Male; Middle Aged; Mosquito Vectors; Parasites; Plasmodium falciparum; Plasmodium vivax; Prevalence; Young Adult
• ISSN: 0022-1899; 1537-6613
• DOI: 10.1093/infdis/jiy060

Falciparum malaria infectivity was relatively low in patients (~6%). None of the falciparum (0/19) and 3 of 28 vivax asymptomatic carriers were infectious to mosquitoes, including those followed up for 2 months. Overall falciparum carrier’s infectivity is low in Cambodia. Abstract Background Eliminating falciparum malaria in Cambodia is a top priority, requiring the implementation of novel tools and strategies to interrupt its transmission. To date, few data are available regarding the contributions to malaria transmission of symptomatic and asymptomatic carriers. Methods Direct-membrane and skin feeding assays (DMFAs, SFAs) were performed, using Anopheles minimus and Anopheles dirus, to determine infectivity of symptomatic falciparum-infected patients and malaria asymptomatic carriers; a subset of the latter were followed up for 2 months to assess their transmission potential. Results By microscopy and real-time polymerase chain reaction, Plasmodium falciparum gametocyte prevalence rates were, respectively, 19.3% (n = 21/109) and 44% (n = 47/109) on day (D) 0 and 17.9% (n = 5/28) and 89.3% (n = 25/28) in recrudescent patients (Drec) (RT-PCR Drec vs D0 P = .002). Falciparum malaria patient infectivity was low on D0 (6.2%; n = 3/48) and in Drec (8.3%; n = 1/12). Direct-membrane feeding assays and SFAs gave similar results. None of the falciparum (n = 0/19) and 3 of 28 Plasmodium vivax asymptomatic carriers were infectious to mosquitoes, including those that were followed up for 2 months. Overall, P. falciparum gametocytemias were low except in a few symptomatic carriers. Conclusions Only symptomatic falciparum malaria patients were infectious to mosquito vectors at baseline and recrudescence, highlighting the need to detect promptly and treat effectively P. falciparum patients.