Avian malaria is a vector-borne disease caused by Plasmodium species, which may affect a broad spectrum of bird families worldwide. In most endemic and migratory birds, Plasmodium infections seem not to cause severe harm; however, non-indigenous species kept in human care such as penguins may experience high morbidity and mortality rates. Fatal avian malaria may also occur in other non-native seabirds such as puffins (Fratercula spp.), but reported cases are scarce.

The aim of this study was to analyze seven cases of sudden death in captive Atlantic puffins (Fratercula arctica) at Berne Animal Park in Switzerland between 2010 and 2020, and to determine the involvement of haemosporidian parasites in the fatal outcome. In all cases, lymphoplasmacytic inflammation, necrotic lesions in several organs and presence of protozoan stages within tissues/erythrocytes or accumulation of iron-based pigment were observed histologically. A one-step multiplex PCR designed to simultaneously detect and discriminate haemosporidia belonging to the genera Plasmodium, Haemoproteus and Leucocytozoon, and a nested PCR detecting Plasmodium and Haemoproteus infections were performed on DNA extracted from formalin-fixed and paraffin-embedded (FFPE) or fresh liver and spleen tissues from five and two birds, respectively. Plasmodium spp. DNA was detected in the tissues from six of seven birds by the one-step multiplex PCR and in five of seven individuals by the nested PCR protocol. Direct sequencing of the amplification products allowed the molecular identification of Plasmodium relictum SGS1 as the involved species in three individuals and Plasmodium matutinum LINN1 in two of these fatal cases. In one bird, no haemosporidian DNA could be amplified from FFPE tissues despite of suggestive histopathological findings. These results indicate that avian malaria represents an important cause of death in captive puffins and it should be considered as a differential diagnosis in unclear or fatal cases in this threatened bird species.

禽疟疾是由一种媒介传播疾病疟原虫种类，这可能会影响到世界范围内的鸟类家族的广谱性。在大多数地方性和候鸟中，疟原虫感染似乎不会造成严重伤害；但是，人类饲养的非本土物种（例如企鹅）可能会出现较高的发病率和死亡率。致命的禽类疟疾也可能发生在其他非本地海鸟中，例如海雀（Fratercula spp。），但报告的病例很少。

这项研究的目的是分析2010年至2020年在瑞士伯尔尼动物公园的7例大西洋捕获的海雀（Fratercula arctica）猝死案例，并确定血吸虫寄生虫与致命结局的关系。在所有情况下，组织学观察到淋巴浆细胞性炎症，几个器官坏死性损伤以及组织/红细胞内原生动物阶段的存在或铁基色素的积累。设计用于同时检测和区分属于疟原虫，变形杆菌和白细胞增生菌属的血球菌的单步多重PCR ，以及用于检测疟原虫和变形杆菌的巢式PCR分别对从福尔马林固定和石蜡包埋（FFPE）或分别来自五只和两只鸟的新鲜肝和脾组织提取的DNA进行感染。疟原虫属 通过一步式多重PCR在7只禽中的6只禽的组织中检测到DNA，通过嵌套PCR方案在7只禽中的5只个体中检测到DNA。扩增产物的直接测序允许分子鉴定为三个个体中的疟原虫SGS1和涉及的疟原虫在其中两个致命案例中，LINN1。尽管有暗示的组织病理学发现，但在一只鸟中，不能从FFPE组织中扩增出血友病DNA。这些结果表明，禽类疟疾是圈养海雀中重要的死亡原因，在这种受威胁的鸟类中，对于不清楚或致命的病例，应将其视为鉴别诊断。