First neuroinvasive human case of West Nile Disease in Southern Italy: Results of the 'One Health' approach

Lessons Learned from West Nile Virus Infection:Vaccinations in Equines and Their Implications for One Health Approaches

Humans and equines are two dead-end hosts of the mosquito-borne West Nile virus (WNV) with similar susceptibility and pathogenesis. Since the introduction of WNV vaccines into equine populations of the United States of America (USA) in late 2002, there have been only sporadic cases of WNV infection in equines. These cases are generally attributed to unvaccinated and under-vaccinated equines. In contrast, due to the lack of a human WNV vaccine, WNV cases in humans have remained steadily high. An average of 115 deaths have been reported per year in the USA since the first reported case in 1999. Therefore, the characterization of protective immune responses to WNV and the identification of immune correlates of protection in vaccinated equines will provide new fundamental information about the successful development and evaluation of WNV vaccines in humans. This review discusses the comparative epidemiology, transmission, susceptibility to infection and disease, clinical manifestation and pathogenesis, and immune responses of WNV in humans and equines. Furthermore, prophylactic and therapeutic strategies that are currently available and under development are described. In addition, the successful vaccination of equines against WNV and the potential lessons for human vaccine development are discussed.

Updated occurrence and bionomics of potential malaria vectors in Europe: a systematic review (2000-2021)

Despite the eradication of malaria across most European countries in the 1960s and 1970s, the anopheline vectors are still present. Most of the malaria cases that have been reported in Europe up to the present time have been infections acquired in endemic areas by travelers. However, the possibility of acquiring malaria by locally infected mosquitoes has been poorly investigated in Europe, despite autochthonous malaria cases having been occasionally reported in several European countries. Here we present an update on the occurrence of potential malaria vector species in Europe. Adopting a systematic review approach, we selected 288 papers published between 2000 and 2021 for inclusion in the review based on retrieval of accurate information on the following Anopheles species: An. atroparvus, An. hyrcanus sensu lato (s.l.), An. labranchiae, An. maculipennis sensu stricto (s.s.), An. messeae/daciae, An. sacharovi, An. superpictus and An. plumbeus. The distribution of these potential vector species across Europe is critically reviewed in relation to areas of major presence and principal bionomic features, including vector competence to Plasmodium. Additional information, such as geographical details, sampling approaches and species identification methods, are also reported. We compare the information on each species extracted from the most recent studies to comparable information reported from studies published in the early 2000s, with particular reference to the role of each species in malaria transmission before eradication. The picture that emerges from this review is that potential vector species are still widespread in Europe, with the largest diversity in the Mediterranean area, Italy in particular. Despite information on their vectorial capacity being fragmentary, the information retrieved suggests a re-definition of the relative importance of potential vector species, indicating An. hyrcanus s.l., An. labranchiae, An. plumbeus and An. sacharovi as potential vectors of higher importance, while An. messeae/daciae and An. maculipennis s.s. can be considered to be moderately important species. In contrast, An. atroparvus and An. superpictus should be considered as vectors of lower importance, particularly in relation to their low anthropophily. The presence of gaps in current knowledge of vectorial systems in Europe becomes evident in this review, not only in terms of vector competence but also in the definition of sampling approaches, highlighting the need for further research to adopt the appropriate surveillance system for each species.

First neuroinvasive human case of West Nile Disease in Southern Italy: Results of the 'One Health' approach

Background

West Nile Disease (WND) is a zoonotic mosquito‐borne infection involving viral pathogens, human and animal hosts, vectors and environment. Cooperation among medical, veterinary and entomological fields has been promoted by the Italian Public Health Authorities, and an integrated West Nile Virus (WNV) Surveillance Plan has been in force in Italy since 2016 to prevent the transmission risk of WND to humans through an early detection of viral circulation by animal and entomological surveillance. This managing model is unique in Europe.

Objectives

This survey aimed at presenting the ‘One Health’ approach applied in 2016 to the first autochthonous human case of West Nile Neuroinvasive Disease (WNND) in Sicily (Southern Italy).

Methods

Serological (anti‐WNV IgM and IgG ELISA, anti‐WNV neutralizing antibodies) and molecular tests were conducted on blood, liquor and urine of a 38‐year‐old man with encephalitis and meningitis. Overall, 2704 adult culicides from 160 mosquito catches were morphologically identified. Female mosquitoes were analysed in pools for WNV RNA detection. Serological (anti‐WNV IgM and IgG ELISA) and molecular analyses for WNV were carried out in 11 horses, 271 chickens and two dogs sampled in farms around the man's residence.

Results and conclusions

WNND was confirmed by serological analysis on patient's liquor and serum. Collected mosquito species included Culex pipiens (93.56%, CI_95% 92.64%–94.49%), Aedes albopictus (5.25%, CI_95% 4.41%–6.09%), Culex hortensis (0.59%, CI_95% 0.30%–0.88%), Culiseta longiareolata (0.55%, CI_95% 0.27%–0.83%) and Anopheles maculipennis s.l. (0.04%, CI_95% –0.04% to 0.11%). Mosquito pools were negative for WNV RNA. Two dogs (100%) and two horses (18.18%, CI_95% –4.61 to 40.97%) resulted positive for anti‐WNV specific antibodies.

The ‘One Health’ approach allowed to report the first human neuroinvasive WND in Sicily and to confirm the local circulation of WNV in animals of the same area where the clinical case occurred, defining the autochthonous origin of the infection.