Nejvíce citovaný článek - PubMed ID 23025175
Development of Leishmania parasites in Culicoides nubeculosus (Diptera: Ceratopogonidae) and implications for screening vector competence
BACKGROUND: Sergentomyia minuta (Diptera: Phlebotominae) is an abundant sand fly species in the Mediterranean basin and a proven vector of reptile parasite Leishmania (Sauroleishmania) tarentolae. Although it feeds preferentially on reptiles, blood meal analyses and detection of Leishmania (Leishmania) infantum DNA in wild-caught S. minuta suggest that occasional feeding may occur on mammals, including humans. Therefore, it is currently suspected as a potential vector of human pathogens. METHODS: A recently established S. minuta colony was allowed to feed on three reptile species (i.e. lizard Podarcis siculus and geckos Tarentola mauritanica and Hemidactylus turcicus) and three mammal species (i.e. mouse, rabbit and human). Sand fly mortality and fecundity were studied in blood-fed females, and the results were compared with Phlebotomus papatasi, vector of Leishmania (L.) major. Blood meal volumes were measured by haemoglobinometry. RESULTS: Sergentomyia minuta fed readily on three reptile species tested, neglected the mouse and the rabbit but took a blood meal on human. However, the percentage of females engorged on human volunteer was low in cage (3%) and feeding on human blood resulted in extended defecation times, higher post-feeding mortality and lower fecundity. The average volumes of blood ingested by females fed on human and gecko were 0.97 µl and 1.02 µl, respectively. Phlebotomus papatasi females readily fed on mouse, rabbit and human volunteer; a lower percentage of females (23%) took blood meal on the T. mauritanica gecko; reptilian blood increased mortality post-feeding but did not affect P. papatasi fecundity. CONCLUSIONS: Anthropophilic behaviour of S. minuta was experimentally demonstrated; although sand fly females prefer reptiles as hosts, they were attracted to the human volunteer and took a relatively high volume of blood. Their feeding times were longer than in sand fly species regularly feeding on mammals and their physiological parameters suggest that S. minuta is not adapted well for digestion of mammalian blood. Nevertheless, the ability to bite humans highlights the necessity of further studies on S. minuta vector competence to elucidate its potential role in circulation of Leishmania and phleboviruses pathogenic to humans.
- Klíčová slova
- Feeding preferences, Leishmania, Phlebotomus, Sand flies, Sergentomyia,
- MeSH
- DNA genetika MeSH
- ještěři * MeSH
- králíci MeSH
- Leishmania * genetika MeSH
- lidé MeSH
- myši MeSH
- Phlebotomus * parazitologie MeSH
- Psychodidae * parazitologie MeSH
- savci genetika MeSH
- zvířata MeSH
- Check Tag
- králíci MeSH
- lidé MeSH
- myši MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- DNA MeSH
Trypanosomes belonging to Trypanosoma theileri group are mammalian blood parasites with keds and horse fly vectors. Our aim is to study to vector specificity of T. theileri trypanosomes. During our bloodsucking Diptera survey, we found a surprisingly high prevalence of T. theileri trypanosomes in mosquitoes (154/4051). Using PCR and gut dissections, we detected trypanosomes of T. theileri group mainly in Aedes mosquitoes, with the highest prevalence in Ae. excrucians (22%), Ae. punctor (21%), and Ae. cantans/annulipes (10%). Moreover, T. theileri group were found in keds and blackflies, which were reported as potential vectors for the first time. The vectorial capacity was confirmed by experimental infections of Ae. aegypti using our isolates from mosquitoes; sand fly Phlebotomus perniciosus supported the development of trypanosomes as well. Infection rates were high in both vectors (47-91% in mosquitoes, 65% in sandflies). Furthermore, metacyclic stages of T. theileri trypanosomes were observed in the gut of infected vectors; these putative infectious forms were found in the urine of Ae. aegypti after a second bloodmeal. On the contrary, Culex pipiens quinquefasciatus was refractory to experimental infections. According to a phylogenetic analysis of the 18S rRNA gene, our trypanosomes belong into three lineages, TthI, ThII, and a lineage referred to as here a putative lineage TthIII. The TthI lineage is transmitted by Brachycera, while TthII and ThIII include trypanosomes from Nematocera. In conclusion, we show that T. theileri trypanosomes have a wide range of potential dipteran vectors, and mosquitoes and, possibly, sandflies serve as important vectors.
- Klíčová slova
- Phlebotomus, Trypanosoma melophagium, Trypanosoma theileri, ked, mosquito, phylogeny, prediuresis, tabanid, transmission, vector,
- Publikační typ
- časopisecké články MeSH
Leishmania parasites, causative agents of leishmaniasis, are currently divided into four subgenera: Leishmania, Viannia, Sauroleishmania and Mundinia. The recently established subgenus Mundinia has a wide geographical distribution and contains five species, three of which have the potential to infect and cause disease in humans. While the other Leishmania subgenera are transmitted exclusively by phlebotomine sand flies (Diptera: Psychodidae), natural vectors of Mundinia remain uncertain. This study investigates the potential of sand flies and biting midges of the genus Culicoides (Diptera: Ceratopogonidae) to transmit Leishmania parasites of the subgenus Mundinia. Sand flies (Phlebotomus argentipes, P. duboscqi and Lutzomyia migonei) and Culicoides biting midges (Culicoides sonorensis) were exposed to five Mundinia species through a chicken skin membrane and dissected at specific time intervals post bloodmeal. Potentially infected insects were also allowed to feed on ear pinnae of anaesthetized BALB/c mice and the presence of Leishmania DNA was subsequently confirmed in the mice using polymerase chain reaction analyses. In C. sonorensis, all Mundinia species tested were able to establish infection at a high rate, successfully colonize the stomodeal valve and produce a higher proportion of metacyclic forms than in sand flies. Subsequently, three parasite species, L. martiniquensis, L. orientalis and L. sp. from Ghana, were transmitted to the host mouse ear by C. sonorensis bite. In contrast, transmission experiments entirely failed with P. argentipes, although colonisation of the stomodeal valve was observed for L. orientalis and L. martiniquensis and metacyclic forms of L. orientalis were recorded. This laboratory-based transmission of Mundinia species highlights that Culicoides are potential vectors of members of this ancestral subgenus of Leishmania and we suggest further studies in endemic areas to confirm their role in the lifecycles of neglected pathogens.
- MeSH
- Ceratopogonidae parazitologie MeSH
- hmyz - vektory parazitologie MeSH
- Leishmania * MeSH
- leishmanióza přenos MeSH
- myši MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
BACKGROUND: Although avian trypanosomes are widespread parasites, the knowledge of their vectors is still incomplete. Despite biting midges (Diptera: Ceratopogonidae) are considered as potential vectors of avian trypanosomes, their role in transmission has not been satisfactorily elucidated. Our aim was to clarify the potential of biting midges to sustain the development of avian trypanosomes by testing their susceptibility to different strains of avian trypanosomes experimentally. Moreover, we screened biting midges for natural infections in the wild. RESULTS: Laboratory-bred biting midges Culicoides nubeculosus were highly susceptible to trypanosomes from the Trypanosoma bennetti and T. avium clades. Infection rates reached 100%, heavy infections developed in 55-87% of blood-fed females. Parasite stages from the insect gut were infective for birds. Moreover, midges could be infected after feeding on a trypanosome-positive bird. Avian trypanosomes can thus complete their cycle in birds and biting midges. Furthermore, we succeeded to find infected blood meal-free biting midges in the wild. CONCLUSIONS: Biting midges are probable vectors of avian trypanosomes belonging to T. bennetti group. Midges are highly susceptible to artificial infections, can be infected after feeding on birds, and T. bennetti-infected biting midges (Culicoides spp.) have been found in nature. Moreover, midges can be used as model hosts producing metacyclic avian trypanosome stages infective for avian hosts.
- Klíčová slova
- Avian parasite, Culicoides nubeculosus, Host specificity, Life-cycle, Transmission, Trypanosoma avium, Trypanosoma bennetti, Trypanosoma culicavium,
- MeSH
- Ceratopogonidae anatomie a histologie parazitologie MeSH
- gastrointestinální trakt parazitologie MeSH
- hmyz - vektory parazitologie MeSH
- hostitelská specificita MeSH
- kanáři parazitologie MeSH
- mikroskopie elektronová rastrovací MeSH
- nemoci ptáků parazitologie přenos MeSH
- polymerázová řetězová reakce MeSH
- ptáci parazitologie MeSH
- Trypanosoma klasifikace genetika fyziologie ultrastruktura MeSH
- trypanozomiáza diagnóza parazitologie přenos veterinární MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
BACKGROUND: Despite their importance in animal and human health, the epidemiology of species of the Leishmania enriettii complex remains poorly understood, including the identity of their biological vectors. Biting midges of the genus Forcipomyia (Lasiohelea) have been implicated in the transmission of a member of the L. enriettii complex in Australia, but the far larger and more widespread genus Culicoides has not been investigated for the potential to include vectors to date. METHODOLOGY/PRINCIPAL FINDINGS: Females from colonies of the midges Culicoides nubeculosus Meigen and C. sonorensis Wirth & Jones and the sand fly Lutzomyia longipalpis Lutz & Nevia (Diptera: Psychodidae) were experimentally infected with two different species of Leishmania, originating from Australia (Leishmania sp. AM-2004) and Brazil (Leishmania enriettii). In addition, the infectivity of L. enriettii infections generated in guinea pigs and golden hamsters for Lu. longipalpis and C. sonorensis was tested by xenodiagnosis. Development of L. enriettii in Lu. longipalpis was relatively poor compared to other Leishmania species in this permissive vector. Culicoides nubeculosus was not susceptible to infection by parasites from the L. enriettii complex. In contrast, C. sonorensis developed late stage infections with colonization of the thoracic midgut and the stomodeal valve. In hamsters, experimental infection with L. enriettii led only to mild symptoms, while in guinea pigs L. enriettii grew aggressively, producing large, ulcerated, tumour-like lesions. A high proportion of C. sonorensis (up to 80%) feeding on the ears and nose of these guinea pigs became infected. CONCLUSIONS/SIGNIFICANCE: We demonstrate that L. enriettii can develop late stage infections in the biting midge Culicoides sonorensis. This midge was found to be susceptible to L. enriettii to a similar degree as Lutzomyia longipalpis, the vector of Leishmania infantum in South America. Our results support the hypothesis that some biting midges could be natural vectors of the L. enriettii complex because of their vector competence, although not Culicoides sonorensis itself, which is not sympatric, and midges should be assessed in the field while searching for vectors of related Leishmania species including L. martiniquensis and "L. siamensis".
- MeSH
- Ceratopogonidae parazitologie MeSH
- gastrointestinální trakt parazitologie MeSH
- hmyz - vektory * MeSH
- křeček rodu Mesocricetus MeSH
- Leishmania enriettii izolace a purifikace MeSH
- leishmanióza parazitologie patologie přenos MeSH
- morčata MeSH
- Psychodidae parazitologie MeSH
- zvířata MeSH
- Check Tag
- morčata MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Sand flies remain the only proven vectors of Leishmania spp. but recent implementation of PCR techniques has led to increasing speculation about "alternative vectors", including biting midges. Here, we summarize that PCR has considerable limits for studing the role of bloodsucking arthropods in the epidemiology of leishmaniasis. The Leishmania life cycle in the sand fly includes a complex series of interactions which are in many cases species-specific, the early phase of the infection is, however, non-specific to sand flies. These facts should be considered in detection of Leishmania in ,"alternative" or "new" vectors to avoid mistaken speculation about their vector competence.
BACKGROUND: Sand fly species of the genus Sergentomyia are proven vectors of reptilian Leishmania that are non-pathogenic to humans. However, a consideration of the role of Sergentomyia spp. in the circulation of mammalian leishmaniasis appears repeatedly in the literature and the possibility of Leishmania transmission to humans remains unclear. Here we studied the susceptibility of colonized Sergentomyia schwetzi to Leishmania donovani and two other Leishmania species pathogenic to humans: L. infantum and L. major. METHODS: Females of laboratory-reared S. schwetzi were infected by cultured Leishmania spp. by feeding through a chicken membrane, dissected at different time intervals post bloodmeal and examined by light microscopy for the abundance and location of infections. RESULTS: All three Leishmania species produced heavy late stage infections in Lutzomyia longipalpis or Phlebotomus duboscqi sand flies used as positive controls. In contrast, none of them completed their developmental cycle in Sergentomyia females; Leishmania promastigotes developed within the bloodmeal enclosed by the peritrophic matrix (PM) but were defecated together with the blood remnants, failing to establish a midgut infection. In S. schwetzi, the PM persisted significantly longer than in L. longipalpis and it was degraded almost simultaneously with defecation. Therefore, Leishmania transformation from procyclic to long nectomonad forms was delayed and parasites did not attach to the midgut epithelium. CONCLUSIONS: Sergentomyia schwetzi is refractory to human Leishmania species and the data indicate that the crucial aspect of the refractoriness is the relative timing of defecation versus PM degradation.
- MeSH
- hmyz - vektory parazitologie MeSH
- Leishmania donovani růst a vývoj patogenita fyziologie MeSH
- leishmanióza viscerální parazitologie přenos MeSH
- lidé MeSH
- Psychodidae parazitologie MeSH
- virulence MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
