Phlebotomine sand fly–borne pathogens in the Mediterranean Basin: Human leishmaniasis and phlebovirus infections

Abstract

Pathogens transmitted to humans by phlebotomine sand flies are neglected, as they cause infectious diseases that are not on the priority list of national and international public health systems. However, the infections caused by protozoa of the Leishmania genus and viruses belonging to the Phlebovirus genus (family Phenuiviridae)—the most significant group of viruses transmitted by sand flies—have a relevant role for human pathology. These infections are emerging in the Mediterranean region and will likely spread in forthcoming decades, posing a complex threat to human health. Four species and 2 hybrid strains of Leishmania are pathogenic for humans in the Mediterranean Basin, with an estimated annual incidence of 239,500–393,600 cases of cutaneous leishmaniasis and 1,200–2,000 cases of visceral leishmaniasis. Among the phleboviruses, Toscana virus can cause neuroinvasive infections, while other phleboviruses are responsible for a typical “3-day fever”; the actual incidence of Phlebovirus infections in the Mediterranean area is unknown, although at least 250 million people are exposed. Here, we reviewed the current literature on epidemiology of sand fly–borne infections in the Mediterranean Basin, with a focus on humans. Our analysis indicates the need for increased public health activities directed to determine the disease burden of these infections as well as to improve their surveillance. Among the emerging challenges concerning sand fly–borne pathogens, the relationships between sand fly–borne protozoa and viruses should be considered in future studies, including epidemiological links between Leishmania and phleboviruses as well as the conditional capacity for these pathogens to be involved in interactions that may evolve towards increased virulence.

Arthropods as vectors of transmissible diseases in Spain

“…[26][27][28] Undoubtedly, the presence of phlebotominae sand flies throughout the Iberian Peninsula is a great threat, since not only do they transmit leishmania, but they are also Toscana virus vectors, which is causing numerous cases of meningoencephalitis in some areas of Spain 29 and other phleboviruses such as the Granada virus (without proven pathogenic power), the Naples virus or the Sicily virus. 30 Another species of mosquito to which special attention is to be paid is Culex pipiens. This species, which is distributed and well represented throughout the Iberian Peninsula, is capable of transmitting the West Nile virus (WNV).…”

Novel Toscana Virus Reverse Genetics System Establishes NSs as an Antagonist of Type I Interferon Responses

“…Toscana virus (TOSV) is a sand fly-borne pathogen of the genus Phlebovirus (order Bunyavirales, family Phenuiviridae) that is responsible for neuro-invasive infections in humans causing meningitis and encephalitis [1,2]. The virus was first isolated in 1971 from Phlebotomus perniciosus and Phlebotomus purified, as described in Section 2.5.…”

Experimental Infection of Dogs with Toscana Virus and Sandfly Fever Sicilian Virus to Determine Their Potential as Possible Vertebrate Hosts

“…There, sandflies are known to transmit both leishmaniasis parasites and sandfly-borne phleboviruses. Because dogs play a decisive role in the natural cycle of leishmaniasis caused by Leishmania (L) infantum, their role as a possible reservoir host for sandfly-borne phleboviruses has been hypothesized [7,8]. Moreover, high phlebovirus seroprevalence rates in dogs have drawn attention to their possible role in the natural virus transmission cycle [8][9][10][11][12][13].…”