Occurrence of Hemogregarine in Two Species of Brazilian Freshwater Turtles

Resumo

Background: Hemogregarines are the most common intraerythrocytic parasites found in reptiles. The genus Haemogregarina has aquatic vertebrates as intermediate hosts, and as definitive hosts the leeches. The genus Hepatozoon can be found parasitizing amphibians, reptiles, birds and mammals and its main vectors invertebrates are mosquitoes, tsetse flies, lice, fleas and mites. The diagnosis of these parasites is done by the technique of blood smear, but modern diagnoses include evaluation of blood by polymerase chain reaction (PCR).  The aim this study was to determine the occurrence of infection by hemogregarine in freshwater turtles, through PCR.

Materials, Methods & Results: Samples from 99 freshwater turtles of species P. expansa and P. geoffroanus of Fundação Zoológico de Brasília,Distrito Federal, Brazil, were used. The animals was captured using a hand net, and were immediately individually identified. The blood samples was collected by puncture of the occipital sinus, and placed into tubes containing sodium heparin anticoagulant for hematologic and molecular analysis. Two different sets of oligonucleotides were used, one to detect hemogregarines and other to detect Hepatozoon sp. infection. The presence of hemogregarine was detected in 20 samples analyzed (n = 99), these eleven samples were positive for hemogregarine, 5 were Hepatozoon sp. and 4  were positive for both oligonucleotides. Laboratory abnormalities were observed in the concentration of total plasma proteins, total serum proteins and globulin, and in the number of thrombocytesin animals positive for hemogregarines and only alterations in the number of thrombocytes were observed in Hepatozoon sp. positive animals of both species.

Discussion: This study showed that there is a high occurrence of infection by hemogregarines in the freshwater turtles samples examinated. The remarkable difficulty of identifying morphological differences, combined with the development of universal oligonucleotides, make further assessments infections hematozoa to be performed using molecular tools and specially  sequencing of the 18S rRNA gene for hemogregarines.  Protein levels in animals depends on the management, diets and normal physiological variations of each species. Hypoproteinemia is commonly observed in reptiles with chronic malnutrition and gastrointestinal parasitism. Therefore it is suggested that the cause of this low level in the measurement of proteins could be directly linked to the presence of hemoparasites because with the infection more animals feeding unless the negative, causing malnutrition, or even the concomitant presence of gastrointestinal parasites, because the study did not evaluate this level of parasitism. Thrombocytes in reptiles participate in blood clotting and some studies have shown that they also have phagocytic capacity. Thrombocytopenia in reptiles is usually a result of excessive use or deficient production. Thus, thrombocytopenia observed in hemogregarines positive animals of this study may suggest that the presence of this group of parasites can cause thrombocytopenia that may be associated with a deficient production of thrombocytes or even greater consumption of these blood cells. The increase of thrombocytes observed in animals positive for Hepatozoon sp. may be related to the defense of the animal, since thrombocytes also have phagocytic activity. No changes were observed in laboratorial tests of P. expansa, which may be due to the small number of this animal species analyzed.