Department of Public Health, Institute of Tropical Medicine, Antwerp, Belgium.
Department of Biochemistry, Institute of Science, Banaras Hindu University, Varanasi, India.
Front Cell Infect Microbiol. 2021 Mar 11;11:645121. doi: 10.3389/fcimb.2021.645121. eCollection 2021.
In the endgame of the elimination initiative of visceral leishmaniasis (VL) on the Indian subcontinent, one of the main questions remaining is whether asymptomatically infected individuals also contribute to transmission. We piloted a minimally invasive microbiopsy device that could help answer this question. While the potential of this device has been previously illustrated in Ethiopia, no such information is available for the setting of the Indian subcontinent. In this proof of concept study we aimed to assess 1) to what extent skin parasite load obtained with the new microbiopsy device correlates with disease status, 2) to what extent skin parasite load correlates with blood parasite load in the same subject, and 3) to what extent the skin parasite load obtained from different sampling sites on the body correlates with one another.
We performed a pilot study in Bihar, India, including 29 VL patients, 28 PKDL patients, 94 asymptomatically infected individuals, 22 endemic controls (EC), and 28 non-endemic controls (NEC). Presence of infection with in the blood was assessed using Direct Agglutination Test, rK39 ELISA, Whole Blood Analysis measuring IFN-γ and qPCR. A skin sample was collected with the microbiopsy device on two different locations on the body. PKDL patients provided a third skin sample from the edge of a PKDL lesion. Parasite load in the skin was measured by qPCR.
We found a clear correlation between the skin parasite load obtained with the microbiopsy device and disease status, with both higher skin parasite loads and higher proportions of positive skin samples in VL and PKDL patients compared to asymptomatics, EC, and NEC. No clear correlation between skin parasite load and blood parasite load was found, but a moderate correlation was present between the skin parasite load in arm and neck samples. In addition, we found four positive skin samples among asymptomatic individuals, and 85% of PKDL lesions tested positive using this microbiopsy device.
In line with previous pilot studies, our results from an Indian setting suggest that the microbiopsy device provides a promising tool to measure skin parasite load, and - if validated by xenodiagnosis studies - could facilitate much needed larger scale studies on infectiousness of human subgroups. In addition, we advocate further evaluation of this device as a diagnostic tool for PKDL.
在印度次大陆消除内脏利什曼病（VL）的行动中，仍有一个主要问题悬而未决，即无症状感染者是否也会助长传播。我们尝试了一种微创微生物活检设备，希望能为此提供答案。尽管该设备的潜力此前已在埃塞俄比亚得到证实，但印度次大陆尚未有相关信息。在这项概念验证研究中，我们旨在评估：1）新的微生物活检设备获得的皮肤寄生虫负荷与疾病状态的相关程度；2）同一受试者皮肤寄生虫负荷与血液寄生虫负荷的相关程度；3）身体不同采样部位获得的皮肤寄生虫负荷彼此之间的相关程度。
我们在印度比哈尔邦进行了一项试点研究，共纳入 29 名 VL 患者、28 名 PKDL 患者、94 名无症状感染者、22 名地方性对照（EC）和 28 名非地方性对照（NEC）。使用直接凝集试验、rK39 ELISA、全血分析测量 IFN-γ和 qPCR 评估血液中 的存在情况。使用微生物活检设备在身体的两个不同部位采集皮肤样本。PKDL 患者从 PKDL 病变的边缘提供第三个皮肤样本。通过 qPCR 测量皮肤寄生虫负荷。
我们发现，使用微生物活检设备获得的皮肤寄生虫负荷与疾病状态之间存在明显的相关性，VL 和 PKDL 患者的皮肤寄生虫负荷更高，且阳性皮肤样本比例也更高，与无症状者、EC 和 NEC 相比。未发现皮肤寄生虫负荷与血液寄生虫负荷之间存在明显的相关性，但手臂和颈部样本的皮肤寄生虫负荷之间存在中度相关性。此外，我们在无症状个体中发现了 4 个阳性皮肤样本，使用这种微生物活检设备，85%的 PKDL 病变呈阳性。
与之前的试点研究一致，我们在印度次大陆的研究结果表明，微生物活检设备为测量皮肤寄生虫负荷提供了一种很有前途的工具，如果通过体外感染研究得到验证，将有助于对人类亚群的传染性进行急需的更大规模研究。此外，我们主张进一步评估该设备作为 PKDL 的诊断工具。
