Division of Parasitic Diseases and Malaria, Centers for Disease Control and Preventiongrid.416738.f, Atlanta, Georgia, USA.
US President's Malaria Initiative, Centers for Disease Control and Preventiongrid.416738.f, Atlanta, Georgia, USA.
J Virol. 2022 Aug 24;96(16):e0067222. doi: 10.1128/jvi.00672-22. Epub 2022 Jul 27.
Rift Valley fever virus (RVFV) is endemic in sub-Saharan Africa (SSA), with outbreaks reported in the Arabian Peninsula and throughout SSA. The natural reservoir for RVFV are ruminants, with livestock populations exceeding 50% exposure rates in some areas of SSA. Transmission to humans can occur through exposure to infected livestock products or multiple species of mosquito vectors. In 2013 and 2014, cross-sectional surveys occurred in two districts of Nacala-a-Velha and Mecubúri in northern Mozambique, and participants provided blood samples for later serological assays. IgG against the N protein of RVFV was detected through multiplex bead assay (MBA). Of the 2,278 persons enrolled between the two surveys and study sites, 181 (7.9%, 95% confidence interval (CI): 6.9%-9.1%) were found to be IgG seropositive with increasing seroprevalence with older age and significantly higher seroprevalence in Nacala-a-Velha (10.5%, 8.8%-12.5%) versus Mecubúri (5.7%, 4.5%-7.1%). Seroprevalence estimates were not significantly different between the 2013 and 2014 surveys. Significant spatial clustering of IgG positive persons were consistent among surveys and within the two districts, pointing toward the consistency of serology data for making population-level assumptions regarding RVFV seroprevalence. A subset of persons ( = 539) provided samples for both the 2013 and 2014 surveys, and a low percentage (0.81%) of these were found to seroconvert between these two surveys. Including the RVFV N protein in an MBA antigen panel could assist elucidate RVFV exposure in SSA. Due to sporadic transmission, human contact with Rift Valley Fever Virus (RVFV) is difficult to ascertain at a population level. Detection of antibodies against RVFV antigens assist in estimating exposure as antibodies remain in the host long after the virus has been cleared. In this study, we show that antibodies against RVFV N protein can be detected from dried blood spot (DBS) samples being assayed by multiplex bead assay. DBS from two districts in northern Mozambique were tested for IgG against the N protein, and 7.9% of all enrolled persons were seropositive. Older persons, males, and persons residing closer to the coast had higher RVFV N protein seroprevalence. Spatial clustering of IgG positive persons was noted in both districts. These results show low exposure rates to RVFV in these two northern districts in Mozambique, and the ability to perform serology for the RVFV N protein from dried blood samples.
裂谷热病毒（RVFV）在撒哈拉以南非洲（SSA）流行，在阿拉伯半岛和整个 SSA 地区都有暴发的报道。RVFV 的自然宿主是反刍动物，在 SSA 的一些地区，牲畜的暴露率超过 50%。人类可以通过接触受感染的牲畜产品或多种蚊虫媒介而感染 RVFV。2013 年和 2014 年，在莫桑比克北部的纳卡拉-贝拉和梅库布里两个地区进行了横断面调查，参与者提供了血液样本进行后续血清学检测。通过多重珠状检测（MBA）检测 RVFV 的 N 蛋白的 IgG。在这两项调查和研究地点之间登记的 2278 人中，有 181 人（7.9%，95%置信区间（CI）：6.9%-9.1%）被发现 IgG 血清阳性，随着年龄的增长血清阳性率逐渐升高，纳卡拉-贝拉（10.5%，8.8%-12.5%）的血清阳性率明显高于梅库布里（5.7%，4.5%-7.1%）。2013 年和 2014 年的调查中，血清阳性率估计值无显著差异。两次调查和两个地区的 IgG 阳性者的空间聚类均一致，表明 RVFV 血清学数据可用于对人群水平的 RVFV 血清阳性率进行假设。一部分人（ = 539）提供了 2013 年和 2014 年调查的样本，这两个人群中只有 0.81%的人在这两次调查之间发生了血清转换。在 MBA 抗原组中加入 RVFV N 蛋白可以帮助阐明 SSA 中的 RVFV 暴露情况。由于传播的间歇性，很难在人群水平上确定人类与裂谷热病毒（RVFV）的接触。检测 RVFV 抗原的抗体有助于估计暴露情况，因为病毒清除后，抗体仍在宿主体内存在。在这项研究中，我们表明，通过多重珠状检测可以从干血斑（DBS）样本中检测到针对 RVFV N 蛋白的抗体。对莫桑比克北部两个地区的 DBS 进行了针对 N 蛋白的 IgG 检测，所有登记人员中有 7.9%呈血清阳性。年龄较大的人、男性和居住在沿海地区附近的人 RVFV N 蛋白血清阳性率较高。两个地区均注意到 IgG 阳性者的空间聚类。这些结果表明，莫桑比克这两个北部地区的 RVFV 暴露率较低，并且能够从干血样中进行 RVFV N 蛋白的血清学检测。
