Ferradas Cusi, Salvatierra Guillermo, Payahuanca David, Contreras Winnie, López-Pérez Andrés M, Hangawatte Therangika A, León Diana, Ghersi Bruno M, Gamboa Ricardo, Villanueva Katia Manzanares, Pinedo-Cancino Viviana, Pesapane Risa, Salmón-Mulanovich Gabriela, Lescano Andrés G, Foley Janet
Emerge, Emerging Diseases and Climate Change Research Unit, School of Public Health and Administration, Universidad Peruana Cayetano Heredia (UPCH), Lima Peru; Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA USA.
Department of Health Sciences, School of Veterinary Medicine, Universidad Peruana de Ciencias Aplicadas (UPC), Lima Peru.
Ticks Tick Borne Dis. 2025 Jan;16(1):102436. doi: 10.1016/j.ttbdis.2024.102436. Epub 2025 Jan 11.
Rickettsiae are a family of ectoparasite-borne bacteria that can produce high morbidity and mortality among humans. There are scarce data on rickettsial ecology in rural areas of the Peruvian Amazon basin, where seroprevalence has not been determined, and the identities of animals acting as reservoirs of these bacteria are not known. We conducted a cross-sectional study in Zungarococha (between 2019 and 2021), a rural community located approximately 20 km away from Iquitos city. Blood samples were collected from humans (175), dogs (123), and cats (12). Blood samples and tissues were collected from black rats (84). Finally, we collected fleas from dogs and cats (222), ticks from dogs (91), and mites from black rats (32). Blood samples from humans, dogs, cats, and black rats were analyzed by indirect immunofluorescence assays (IFA) to detect IgG antibodies against rickettsias. We screened ectoparasites and black rat tissues by real-time-PCR (qPCR). Positive ectoparasites were further assessed by PCR and DNA amplicon sequencing. Non-parametric tests were used to evaluate factors associated with being seropositive among human adults. IgG seroprevalences were 38.3 %, 58.5 %, 16.7 % and 48.1 % among humans, dogs, cats, and rats, respectively. Among humans, only male gender was statistically associated with having IgG antibodies against Rickettsia spp. (p-value=0.049, chi-square test). Different ectoparasites were identified, including Ctenocephalides felis from cats and dogs, Rhipicephalus sanguineus s.l. from dogs, and Laelaps nuttalli from black rats. Rhipicephalus sanguineus s.l. (2/91 ticks) and Ct. felis (53/56 fleas and 55/55 flea pools) were qPCR-positive for Rickettsia spp. Recovered genetic material from 53 Ct. felis was sequenced and all were identified as Rickettsia asembonensis. All tissue samples from black rats were negative by qPCR. Humans, dogs, cats, and black rats are exposed to spotted fever group rickettsiae in rural areas surrounding Iquitos. As reported in urban areas, R. asembonensis is the main Rickettsia species circulating in rural areas surrounding Iquitos and Ct. felis appears to be the main vector.
立克次氏体是一类由外寄生虫传播的细菌，可在人类中导致高发病率和死亡率。在秘鲁亚马逊河流域的农村地区，关于立克次氏体生态学的数据稀缺，该地区的血清阳性率尚未确定，作为这些细菌宿主的动物身份也不清楚。我们在距离伊基托斯市约20公里的农村社区宗加罗科查（2019年至2021年期间）开展了一项横断面研究。采集了人类（175例）、狗（123只）和猫（12只）的血样。采集了黑鼠（84只）的血样和组织。最后，我们从狗和猫身上采集了跳蚤（222只）、从狗身上采集了蜱（91只）、从黑鼠身上采集了螨（32只）。通过间接免疫荧光试验（IFA）分析人类、狗、猫和黑鼠的血样，以检测抗立克次氏体的IgG抗体。我们通过实时聚合酶链反应（qPCR）筛查外寄生虫和黑鼠组织。对qPCR呈阳性的外寄生虫进一步进行聚合酶链反应和DNA扩增子测序。使用非参数检验评估与成年人类血清阳性相关的因素。人类、狗、猫和鼠的IgG血清阳性率分别为38.3%、58.5%、16.7%和48.1%。在人类中，只有男性性别与抗立克次氏体属的IgG抗体存在统计学关联（p值=0.049，卡方检验）。鉴定出了不同的外寄生虫，包括来自猫和狗的猫栉首蚤、来自狗的血红扇头蜱指名亚种以及来自黑鼠的纳氏厉螨。血红扇头蜱指名亚种（91只蜱中有2只）和猫栉首蚤（56只跳蚤中有53只以及55个跳蚤样本池中有55个）的立克次氏体属qPCR呈阳性。对53只猫栉首蚤回收的遗传物质进行了测序，所有样本均鉴定为阿氏立克次氏体。黑鼠的所有组织样本qPCR均为阴性。在伊基托斯周边农村地区，人类、狗、猫和黑鼠都接触到斑点热群立克次氏体。如在城市地区所报道的那样，阿氏立克次氏体是伊基托斯周边农村地区传播的主要立克次氏体物种，猫栉首蚤似乎是主要传播媒介。
