Saurian malaria: development of sporozoites in two species of phlebotomine sandflies

Diversity and role of cave-dwelling hematophagous insects in pathogen transmission in the Afrotropical region

The progressive anthropization of caves for food resources or economic purposes increases human exposure to pathogens that naturally infect cave-dwelling animals. The presence of wild or domestic animals in the immediate surroundings of caves also may contribute to increasing the risk of emergence of such pathogens. Some zoonotic pathogens are transmitted through direct contact, but many others require arthropod vectors, such as blood-feeding insects. In Africa, hematophagous insects often play a key role in the epidemiology of many pathogens; however, their ecology in cave habitats remains poorly known. During the last decades, several investigations carried out in Afrotropical caves suggested the medical and veterinary importance particularly of insect taxa of the Diptera order. Therefore, the role of some of these insects as vectors of pathogens that infect cave-dwelling vertebrates has been studied. The present review summarizes these findings, brings insights into the diversity of cave-dwelling hematophagous Diptera and their involvement in pathogen transmission, and finally discusses new challenges and future research directions.

Blood parasites in reptiles imported to Germany

Though international trade is increasing, the significance of imported reptiles as carriers of pathogens with relevance to animal and human health is largely unknown. Reptiles imported to Germany were therefore investigated for blood parasites using light microscopy, and the detected parasites were morphologically characterized. Four hundred ten reptiles belonging to 17 species originating from 11 Asian, South American and African countries were included. Parasites were detected in 117 (29%) of individual reptiles and in 12 species. Haemococcidea (Haemogregarina, Hepatozoon, Schellackia) were found in 84% of snakes (Python regius, Corallus caninus), 20% of lizards (Acanthocercus atricollis, Agama agama, Kinyongia fischeri, Gekko gecko) and 50% of turtles (Pelusios castaneus). Infections with Hematozoea (Plasmodium, Sauroplasma) were detected in 14% of lizards (Acanthocercus atricollis, Agama agama, Agama mwanzae, K. fischeri, Furcifer pardalis, Xenagama batillifera, Acanthosaura capra, Physignathus cocincinus), while those with Kinetoplastea (Trypanosoma) were found in 9% of snakes (Python regius, Corallus caninus) and 25 % of lizards (K. fischeri, Acanthosaura capra, G. gecko). Nematoda including filarial larvae parasitized in 10% of lizards (Agama agama, Agama mwanzae, K. fischeri, Fu. pardalis, Physignathus cocincinus). Light microscopy mostly allowed diagnosis of the parasites' genus, while species identification was not possible because of limited morphological characteristics available for parasitic developmental stages. The investigation revealed a high percentage of imported reptiles being carriers of parasites while possible vectors and pathogenicity are largely unknown so far. The spreading of haemoparasites thus represents an incalculable risk for pet reptiles, native herpetofauna and even human beings.

Nonspecific patterns of vector, host and avian malaria parasite associations in a central African rainforest

Malaria parasites use vertebrate hosts for asexual multiplication and Culicidae mosquitoes for sexual and asexual development, yet the literature on avian malaria remains biased towards examining the asexual stages of the life cycle in birds. To fully understand parasite evolution and mechanism of malaria transmission, knowledge of all three components of the vector-host-parasite system is essential. Little is known about avian parasite-vector associations in African rainforests where numerous species of birds are infected with avian haemosporidians of the genera Plasmodium and Haemoproteus. Here we applied high resolution melt qPCR-based techniques and nested PCR to examine the occurrence and diversity of mitochondrial cytochrome b gene sequences of haemosporidian parasites in wild-caught mosquitoes sampled across 12 sites in Cameroon. In all, 3134 mosquitoes representing 27 species were screened. Mosquitoes belonging to four genera (Aedes, Coquillettidia, Culex and Mansonia) were infected with twenty-two parasite lineages (18 Plasmodium spp. and 4 Haemoproteus spp.). Presence of Plasmodium sporozoites in salivary glands of Coquillettidia aurites further established these mosquitoes as likely vectors. Occurrence of parasite lineages differed significantly among genera, as well as their probability of being infected with malaria across species and sites. Approximately one-third of these lineages were previously detected in other avian host species from the region, indicating that vertebrate host sharing is a common feature and that avian Plasmodium spp. vector breadth does not always accompany vertebrate-host breadth. This study suggests extensive invertebrate host shifts in mosquito-parasite interactions and that avian Plasmodium species are most likely not tightly coevolved with vector species.

Further parasites of the family Garniidae (Coccidiida: Haemosporidiidea) in Brazilian lizards. Fallisia effusa gen.nov., sp.nov. and Fallisia modesta gen.nov., sp.nov

Fallisia effusa gen.nov., sp.nov. (Haemosporidiidea: Garniidae) is described in the teiid lizard, Neusticurus bicarinatus, from Pará State, north Brazil. Schizogony and gametogony both take place within thrombocytes and white cells of the peripheral blood. There is no development in the red blood cells, by which character the organism is differentiated from Garnia, the other known genus within the family. Another species, Fallisia modesta gen.nov., sp.nov., is described in the iguanid lizard, Tropidurus torquatus hispidus, also from Pará, Brazil. It is distinguished from F. effusa by its development principally in the lymphocytes, as opposed to the thrombocytes. There are other, striking morphological differences between the two species. It is recommended that great care is needed in the interpretation of so-called ‘exo-erythrocytic stages’ of saurian plasmodia, which may well really belong to members of the Garniidae, in mixed infections.

Detection of a Malaria Parasite (Plasmodium mexicanum) in Ectoparasites (Mites and Ticks), and Possible Significance for Transmission

Two species of sandflies (Lutzomyia) are competent vectors of Plasmodium mexicanum, a malaria parasite of lizards. The very patchy distribution of sites with high P. mexicanum prevalence in the lizards, and often low or even nil sandfly density at such sites, provoked an evaluation of 2 common lizard ectoparasites, the tick Ixodes pacificus and the mite Geckobiella occidentalis, as potential passive vectors. Plasmodium sp.-specific polymerase chain primers were used to amplify a long segment of the mitochondrial cytochrome b gene that is unlikely to survive intact if the parasite cells are killed within a blood-feeding arthropod. The segment was strongly amplified from sandflies (the positive control for the method) from 1 to 96 hr postfeeding on an infected lizard. For ticks, the gene fragment was poorly amplified at 0 hr postfeed, and not amplified after 2 hr. In contrast, strong amplification of the parasite DNA was observed from mites from 0 to 20 hr postfeed, and weak amplification even at 96 hr.

Fossil psychodoid flies and their relation to parasitic diseases

Psychodid sand flies are blood-sucking fly vectors of several parasitic diseases. The oldest definitive record of this group is from the Lower Cretaceous amber of Lebanon (circa-135 to -125 My), but the high diversity within this group supports the idea that the psychodoids originated much earlier in history. The palaeontology demonstrates that the Lower Creataceous representatives of the different subfamilies of Psychodidae had similar morphology and were blood-feeders, which supports Hennig's hypothesis on the ground plan structure of this family. Historical relationship between sand flies and diseases is unclear up to the present time, but this relationship could be as old as the origin of psychodoids because of the blood-feeding life mode.

Seroepidemiology of Bartonella vinsonii subsp. berkhoffii infection in California coyotes, 1994-1998

The prevalence of antibodies to Bartonella vinsonii subsp. berkhoffii in coyotes (Canis latrans) in California ranged from 51% in central to 34% in southern and 7% in northern California. Seropositive coyotes were more likely to be from coastal than inland counties (p clustered distribution of Bartonella seropositivity in coyotes suggests that B. vinsonii subsp. berkhoffii infection is vectorborne. Further investigation is warranted to evaluate which arthropods are vectors and what the mode of transmission is from wildlife to domestic dogs and possibly humans.

Saurian malaria in Kenya: epidemiological features of malarial infections in lizard populations of the West Pokot District

During investigations into the prevalence of malarial parasites among lizards in the West Pokot District in Kenya, 179 lizards comprising eight species were caught. Examination of the Giemsa-stained smears made from their blood showed that 34 lizards were infected with Plasmodium species. Fifteen lizards were infected with a single species of Plasmodium and 19 carried multiple infections, the maximum, in four lizards, was four species. There were 19 combinations of parasite infections. Seventeen Plasmodium species were identified, the commonest being P. icipeensis. Only two of the eight lizard species were infected: the skink Mabuya striata and the agamid Agama agama. Eight of the Plasmodium species infected both; another eight species infected M. striata only but three of these have been described from different lizard families elsewhere in Africa. P. robinsoni infected A. agama only, although it was first described from another lizard family in another part of Africa. The epidemiological significance of these results is discussed.