Diet of feral cats during the Scopoli’s shearwater breeding season on Linosa Island, Mediterranean Sea

Elimination of Dirofilaria immitis Infection in Dogs, Linosa Island, Italy, 2020-2022

On Linosa Island, Italy, Dirofilaria immitis infection has been hyperendemic in dogs and seroprevalent among islanders. In 2020, we implemented a heartworm disease elimination program on Linosa Island. Of 54 dogs tested for D. immitis antigen and microfilariae, 28 had positive results and received treatment with oral doxycycline twice daily for 4 weeks plus topical imidacloprid/moxidectin monthly for 12 months. The 26 dogs with negative results received monthly topical imidacloprid/moxidectin as preventive. During month 1, the number of microfilaremic dogs was reduced by 76.5%. From month 2 on, all animals were microfilariae negative, and during months 3 to 9, the number of antigen-positive dogs decreased progressively. Treatment of positive dogs coupled with chemoprophylaxis for noninfected dogs was effective, protecting them from new infections. The elimination program reduced the risk for human infection, representing a One Health paradigm. Monitoring and chemoprophylaxis are advocated to maintain the status of heartworm disease-free area.

An (Un)Expected Threat for a Regionally Near-Threatened Species: A Predation Case of a Persian Squirrel on an Insular Ecosystem

One of the most successful predators on island ecosystems is the domestic cat, which is considered responsible for the decline of numerous species' populations. This can be estimated by the analysis of cats' dietary habits, yet prey identification is not always possible, and thus, in cases where precise prey identification is required, one of the most accurate methods derives from observing the hunting process. However, the cryptic nature of the feral cats and the constant vigilance of the species that are preyed upon make the observation process difficult, especially when the prey has a low population density. Here, we report for the first time such a case: a feral cat that has ambushed, killed, and consumed a regionally near-threatened species, the Persian squirrel. This incidental observation happened in the squirrel's westernmost end of its distribution, the island of Lesvos, Greece. Due to the unexpectedness of the event, in the following days, we estimated both the squirrels' and cats' population density. Results showed that while the density of the squirrels is moderate, the population density of the feral cats is almost fifteen times higher. For this reason, management actions need to be taken in an effort to minimize the impacts of feral cats on the native species of the island.

Misleading estimates of economic impacts of biological invasions: Including the costs but not the benefits

The economic costs of non-indigenous species (NIS) are a key factor for the allocation of efforts and resources to eradicate or control baneful invasions. Their assessments are challenging, but most suffer from major flaws. Among the most important are the following: (1) the inclusion of actual damage costs together with various ancillary expenditures which may or may not be indicative of the real economic damage due to NIS; (2) the inclusion of the costs of unnecessary or counterproductive control initiatives; (3) the inclusion of controversial NIS-related costs whose economic impacts are questionable; (4) the assessment of the negative impacts only, ignoring the positive ones that most NIS have on the economy, either directly or through their ecosystem services. Such estimates necessarily arrive at negative and often highly inflated values, do not reflect the net damage and economic losses due to NIS, and can significantly misguide management and resource allocation decisions. We recommend an approach based on holistic costs and benefits that are assessed using likely scenarios and their counter-factual.

Detection of Dirofilaria DNA and host blood-meal identification in Culicoides paolae biting-midges

The vectorial role of blood-sucking arthropods, other than mosquitoes, has been explored for Dirofilaria immitis and Dirofilaria repens which are filarioids of increasing interest due to their zoonotic potential. Given the expansion of canine heartworm infection in southern Europe due to D. immitis and the report of the infection in Linosa Island (Sicily, Italy), we investigated and focused on the potential involvement of Culicoides spp. in Dirofilaria spp. transmission as well as the blood-meal source in Dirofilaria spp. molecularly positive biting midges. Out of 1791 specimens collected 1773 were morphologically and molecularly identified as Culicoides paolae and 18 as Culicoides obsoletus complex. Of the 1596 females, 4 (0.26%) parous C. paolae tested positive for D. immitis and D. repens (i.e. 2 Culicoides specimens for each filarial species), of which D. immitis-positive samples fed on both humans and dogs and D. repens-positive samples fed only on humans. The detection of D. immitis and D. repens DNA in Culicoides midges suggests their potential involvement in the epidemiology of the filarial nematodes, which may be of medical and veterinary importance in hyper-endemic areas. Findings of this study shed new light on the epidemiology of Dirofilaria spp. infections indicating that further investigations are needed.

Dirofilaria immitis infection in the Pelagie archipelago: The southernmost hyperendemic focus in Europe

Dirofilaria immitis and Dirofilaria repens are mosquito-borne filarioids of zoonotic concern, which primarily cause canine heartworm disease (HWD) and subcutaneous dirofilariosis, respectively. The geographical distribution of these nematodes is constantly changing, due to many factors such as the colonization by new invasive mosquito species, the increased movement of animals and the absence of chemoprophylactic strategies in non-endemic regions. Although HWD has always been considered endemic in northern Italy, an increase in the prevalence of this disease has been recorded in the last decades in central and southern regions. We describe the southernmost hyperendemic European focus of heartworm disease in the Pelagie archipelagos. From June to November 2020, 157 dogs and 46 cats were sampled in Linosa and Lampedusa islands for the detection of Dirofilaria immitis and Dirofilaria repens by modified Knott's, rapid antigen and molecular tests. Mosquitoes were collected using CDC light and BG sentinel-2 traps and aspirators, and tested for host blood meal and Dirofilaria spp. DNA. Out of 56 dogs in Linosa and 101 in Lampedusa, 33 (i.e. 58.9%) and 8 (i.e. 7.9%) were positive to D. immitis and D. repens, respectively. Three cats scored positive to D. immitis (i.e. 17.6%) in Linosa. Six mosquito species were identified, and the abdomen of a non-engorged Aedes albopictus was positive for D. immitis and human DNA. The results suggest that D. immitis infection could spread to new previously non-endemic territories in southern Europe, representing a real threat to animal and human health.