Increased investment in gametocytes in asymptomatic Plasmodium falciparum infections in the wet season.
Increased investment in gametocytes in asymptomatic Plasmodium falciparum infections in the wet season.
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DOI：
10.1186/s12879-020-05761-6
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发表时间：
2021-01-09
影响因子：
3.7
通讯作者：
Koepfli C
中科院分区：
文献类型：
--
作者：
Oduma CO;Ogolla S;Atieli H;Ondigo BN;Lee MC;Githeko AK;Dent AE;Kazura JW;Yan G;Koepfli C
由无症状感染引起的传播日益被认为是对消除疟疾的威胁。在许多地区，疟疾传播是季节性的。目前尚不清楚恶性疟原虫是否调节其在传播中的投资以适应季节性媒介丰富。我们在肯尼亚西部的两个地点，在媒介丰富的雨季和旱季分别采样了1116个无症状个体和1743个无症状个体，代表不同的传播强度(Chulaimbo，中等传播，和Homa Bay，低传播)。血样用qPCR法筛查恶性疟原虫，配子体用Pfs25 RT-qPCR法筛查。QPCR检测的寄生虫感染率分别为27.1%(Chulaimbo，干)、48.2%(Chulaimbo，湿)、9.4%(Homabay，干)和7.8%(Homabay，湿)。平均寄生虫密度在不同季节没有差异(P = 0.562)。456例感染中有119例(26.1%)检测到Pfs25转录本。在雨季，含有可检测到的配子体的感染较少(22.3%vs.33.8%，P = 0.009)，但密度高出3倍(湿：3.46转录/ul，干：1.0转录/ul，P <； 0.001)。在旱季，4.0%的感染者携带中到高密度的配子体，可能具有感染性(>； ，每2微升血液中有1个配子体)，而在雨季这一比例为7.9%。5-15 岁的儿童中有76.7%的配子体密度为中到高。寄生虫在雨季增加了它们在传播方面的投资，这反映在配子体密度较高。尽管配子体密度增加，但寄生虫密度在不同季节保持相似，往往低于显微镜或快速诊断测试的检测极限，因此很大比例的感染性感染将在雨季逃脱人口筛查。在设计疟疾控制措施时，需要考虑无症状感染中配子细胞症的季节性变化。网上版载有补充材料，可在10.1186/s12879-020-05761-6查阅。
Transmission stemming from asymptomatic infections is increasingly being recognized as a threat to malaria elimination. In many regions, malaria transmission is seasonal. It is not well understood whether Plasmodium falciparum modulates its investment in transmission to coincide with seasonal vector abundance. We sampled 1116 asymptomatic individuals in the wet season, when vectors are abundant, and 1743 in the dry season, in two sites in western Kenya, representing different transmission intensities (Chulaimbo, moderate transmission, and Homa Bay, low transmission). Blood samples were screened for P. falciparum by qPCR, and gametocytes by pfs25 RT-qPCR. Parasite prevalence by qPCR was 27.1% (Chulaimbo, dry), 48.2% (Chulaimbo, wet), 9.4% (Homabay, dry), and 7.8% (Homabay, wet). Mean parasite densities did not differ between seasons (P = 0.562). pfs25 transcripts were detected in 119/456 (26.1%) of infections. In the wet season, fewer infections harbored detectable gametocytes (22.3% vs. 33.8%, P = 0.009), but densities were 3-fold higher (wet: 3.46 transcripts/uL, dry: 1.05 transcripts/uL, P < 0.001). In the dry season, 4.0% of infections carried gametocytes at moderate-to-high densities likely infective (> 1 gametocyte per 2 uL blood), compared to 7.9% in the wet season. Children aged 5–15 years harbored 76.7% of infections with gametocytes at moderate-to-high densities. Parasites increase their investment in transmission in the wet season, reflected by higher gametocyte densities. Despite increased gametocyte densities, parasite density remained similar across seasons and were often below the limit of detection of microscopy or rapid diagnostic test, thus a large proportion of infective infections would escape population screening in the wet season. Seasonal changes of gametocytemia in asymptomatic infections need to be considered when designing malaria control measures. The online version contains supplementary material available at 10.1186/s12879-020-05761-6.
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