Seasonality and transmissibility of Plasmodium ovale in Bagamoyo District, Tanzania

被引：16

作者：

Tarimo, Brian B. ^{[1
]}

Nyasembe, Vincent O. ^{[2
]}

Ngasala, Billy ^{[3
]}

Basham, Christopher ^{[4
]}

Rutagi, Isaack J. ^{[1
]}

Muller, Meredith ^{[4
]}

Chhetri, Srijana B. ^{[4
]}

Rubinstein, Rebecca ^{[4
]}

Juliano, Jonathan J. ^{[4
]}

Loya, Mwajabu ^{[3
]}

Dinglasan, Rhoel R. ^{[2
]}

Lin, Jessica T. ^{[4
]}

Mathias, Derrick K. ^{[5
]}

机构：

[1] Ifakara Hlth Inst, Dept Environm Hlth & Ecol Sci, Vector Immun & Transmiss Biol Unit, Bagamoyo Off, POB 74, Bagamoyo 61301, Coast Region, Tanzania

[2] Univ Florida, Coll Vet Med, Emerging Pathogens Inst, Dept Infect Dis & Immunol, Gainesville, FL 32611 USA

[3] Muhimbili Univ Hlth & Allied Sci, Sch Publ Hlth & Social Sci, Dept Parasitol & Med Entomol, Dar Es Salaam 11103, Tanzania

[4] Univ N Carolina, Sch Med, Inst Global Hlth & Infect Dis, Chapel Hill, NC 27599 USA

[5] Univ Florida, Inst Food & Agr Sci, Dept Entomol & Nematol, Florida Med Entomol Lab, Vero Beach, FL 32962 USA

来源：

PARASITES & VECTORS | 2022年 / 15卷 / 01期

基金：

美国国家卫生研究院;

关键词：

Plasmodium ovale; Plasmodium falciparum; Malaria; Asymptomatic; Tanzania; Anopheles gambiae; Direct feeding assay (DFA); MALARIAE;

D O I：

10.1186/s13071-022-05181-2

中图分类号：

R38 [医学寄生虫学]; Q [生物科学];

学科分类号：

07 ; 0710 ; 09 ; 100103 ;

摘要：

Background: Plasmodium ovale is a neglected malarial parasite that can form latent hypnozoites in the human liver. Over the last decade, molecular surveillance studies of non-falciparum malaria in Africa have highlighted that P. ovale is circulating below the radar, including areas where Plasmodium falciparum is in decline. To eliminate malaria where P. ovale is endemic, a better understanding of its epidemiology, asymptomatic carriage, and transmission biology is needed. Methods: We performed a pilot study on P. ovale transmission as part of an ongoing study of human-to-mosquito transmission of P. falciparum from asymptomatic carriers. To characterize the malaria asymptomatic reservoir, cross-sectional qPCR surveys were conducted in Bagamoyo, Tanzania, over three transmission seasons. Positive individuals were enrolled in transmission studies of P. falciparum using direct skin feeding assays (DFAs) with Anopheles gambiae s.s. (IFAKARA strain) mosquitoes. For a subset of participants who screened positive for P. ovale on the day of DFA, we incubated blood-fed mosquitoes for 14 days to assess sporozoite development. Results: Molecular surveillance of asymptomatic individuals revealed a P. ovale prevalence of 11% (300/2718), compared to 29% (780/2718) for P. falciparum. Prevalence for P. ovale was highest at the beginning of the long rainy season (15.5%, 128/826) in contrast to P. falciparum, which peaked later in both the long and short rainy seasons. Considering that these early-season P. ovale infections were low-density mono-infections (127/128), we speculate many were due to hypnozoite-induced relapse. Six of eight P. ovale-infected asymptomatic individuals who underwent DFAs successfully transmitted P. ovale parasites to A. gambiae. Conclusions: Plasmodium ovale is circulating at 4-15% prevalence among asymptomatic individuals in coastal Tanzania, largely invisible to field diagnostics. A different seasonal peak from co-endemic P. falciparum, the capacity to relapse, and efficient transmission to Anopheles vectors likely contribute to its persistence amid control efforts focused on P. falciparum.

引用

页数：6

共 16 条

[1] Plasmodium interspecies interactions during a period of increasing prevalence of Plasmodium ovale in symptomatic individuals seeking treatment: an observational study [J].