Ultrastructural studies on the sporogony of Hepatozoon spp. in Culex quinquefasciatus Say, 1823 fed on infected Caiman crocodilus and Boa constrictor from northern Brazil

Abstract

Laboratory reared Culex quinquefasciatus Say, 1823 originating from the vicinity of Belem, in northern Brazil, were allowed to engorge on caimans (Caiman c. crocodilus) infected with Hepatozoon caimani (Carini, 1909) and boas (Boa constrictor) infected with H. cf. terzii (Sambon and Seligmann, 1907) both from Para State. Engorged mosquitoes killed on successive days post-feeding (p.f.) were studied by transmission electron microscopy. Images of oocysts from 13 days p.f., caiman-fed mosquitoes were also examined by scanning electron microscopy. The Hepatozoon spp. from the respective hosts differed in their ability to develop in C. quinquefasciatus. Most female mosquitoes fed on caimans, became fully engorged, and survived beyond 22 days p.f., whereas those engorged on boa became debilitated and did not survive beyond 9 days p.f. In boa-fed mosquitoes oocysts were found on the 6th day p.f. The few mosquitoes surviving to the 9th day p.f. contained either undivided oocysts or those that had already commenced sporogenic division. By 8-10 days p.f. caiman-fed mosquitoes contained uninucleate oocysts. Sporogonic divisions were observed from day 12 p.f. onwards. Although sporogenic development conformed in general with the previously reported accounts, the study allowed a more detailed examination of the plasmalemmal endocytotic system, and the consolidation of the crystalline body in specialized 'factories' of cystalline material. Sporozoite differentiation occasionally started on the 18th day p.f., but otherwise was observed only on day 22 p.f.

Hepatozoon caimani in Caiman crocodilus yacare (Crocodylia, Alligatoridae) from North Pantanal, Brazil

“…Based on morphologic and morphometric characteristics, Hepatozoon caimani have been found described as the only Hepatozoon species parasitizing Caiman latirostris (SMITH, 1996), Caiman crocodilus (LAINSON, 1977;LAINSON et al, 2003) and Caiman yacare (LAINSON et al, 2003;VIANA & MARQUES, 2005;VIANA et al, 2010a) in South America.…”

“…Culex (Meloconion) mosquitoes are the H. caimani natural vectors, where sporogonic phase takes place (LAINSON et al, 2003;VIANA et al, 2010b). Despite of that, the possibility of the infected-invertebrate hosts being eaten by caimans is minimal (LAINSON et al, 2003;PAPERNA & LAINSON, 2003).…”

“…Despite of that, the possibility of the infected-invertebrate hosts being eaten by caimans is minimal (LAINSON et al, 2003;PAPERNA & LAINSON, 2003). Caiman yacare become infected for the first time as juveniles, when its diet changes from ingestion of invertebrates to predation of anurans and fishes (VIANA et al, 2010a).…”

“…In South America, predation of insectivorous vertebrates appears to be the main transmission route of H. caimani (VIANA et al, 2012). Hepatozoon caimani-cystozoites have been found in amphibian tissues of the following species: Leptodactylus fuscus, Leptodactylus chaquensis, Leptodactylus podicipinis, Scinax nasicus and Rana catesbeiana (LAINSON et al, 2003;VIANA et al, 2012), suggesting that anurans are paratenic hosts for H. caimani, although frogs are not part of caiman's diet. The characid fish Metynnis sp., when fed with C. quinquefasciatus previously engorged on naturally H. caimani-infected caiman showed cysts harbouring cystozoites identical to those of H. caimani, suggesting its role as paratenic hosts for this haemoprotozoa (PEREIRA et al, 2014).…”

“…The characid fish Metynnis sp., when fed with C. quinquefasciatus previously engorged on naturally H. caimani-infected caiman showed cysts harbouring cystozoites identical to those of H. caimani, suggesting its role as paratenic hosts for this haemoprotozoa (PEREIRA et al, 2014). Although some attempts were unsuccessful in proving the experimental transmission of Hepatozoon to crocodilians (PESSÔA et al, 1972;LAINSON et al, 2003), structures similar to Hepatozoon oocystis have been recently described in these invertebrates collected from Caiman yacare's oral cavity (SOARES et al, 2017a).…”