Prevention and Treatment of Haemogregarinosis in Freshwater Soft-Shelled Turtles and Turtles

Haemogregarinosis is a disease caused by parasitic Haemogregarina. Haemogregarina is a sporozoan belonging to the order Eucoccidiida and the family Haemogregarinidae. Haemogregarina parasitizes the blood cells, liver cells and Kupffer cells of soft-shelled turtles and turtles and reproduces there.

(1) Pathogen

Haemogregarina. According to Chai Jianyun et al. (1990), 6 species of Haemogregarina have been found in the bodies of soft-shelled turtles and turtles in China. Taking Haemogregarina sinensis as an example, in the Chinese soft-shelled turtle, there are 3 stages:

(1) The mature tissue schizont in the Kupffer cells of the liver is oval or spherical, measuring 17.92-18.24 micrometres x 14.84-15.24 micrometres, and produces 15-20 merozoites; the merozoites are short rod-shaped.

(2) The proliferation of schizonts in the deep blood occurs in the red blood cells of the hepatic sinuses. The schizonts are of X type and Y type; the two are similar in size and shape, both being columnar. The X-type schizont produces 14-18 small merozoites, which are wedge-shaped; the Y-type schizont produces 4-8 large merozoites, which are rod-shaped. The macrogametocyte is kidney-shaped, and the microgametocyte is comma-shaped with a small tail at the posterior end.

(3) The early schizont in the peripheral blood cells is broadly kidney-shaped and produces 6-12 merozoites; the merozoites are banana-shaped. The mid-stage schizont produces 6-10 merozoites; the late-stage schizont produces 2 merozoites. The gametocytes are derived from Y-type merozoites, and the trophozoite is the intermediate stage in the development from the merozoites of the previous generation to the schizonts of the next generation. The Chinese soft-shelled turtle is the intermediate host of Haemogregarina sinensis.

The turtle leech is the final host of Haemogregarina sinensis. After the turtle leech sucks the blood of a diseased soft-shelled turtle, Haemogregarina sinensis develops in the digestive tract of the leech, including two stages: gametogony and sporogony. Gametogony is characterized by the fusion of the gametocytes of the two sexes first, followed by gamete differentiation, producing 4 male gamete nuclei, one of which fertilizes the female gamete nucleus to form the zygote nucleus. Sporogony begins with the nuclear division of the uninucleate oocyst and finally forms a mature oocyst with 8 naked sporozoites, which disintegrates and releases the sporozoites.

(2) Epidemiology

According to Chai Jianyun et al. (1990), 248 Chinese soft-shelled turtles, 40 turtles, 25 yellow-margined box turtles and 2 big-headed turtles were dissected and examined. Haemogregarina was not found only in the big-headed turtles (because only 2 were examined); the other 3 species of soft-shelled turtles and turtles were all parasitized by Haemogregarina. Among them, the infection rate of the Chinese soft-shelled turtle was 83.9%, and the infection intensity was 19.7% (infection intensity was calculated as the number of infected red blood cells per 1000 red blood cells). From May to September each year, both the infection rate and infection intensity of Haemogregarina show peaks, which is the result of the active movement of the host and the vigorous schizogonic proliferation of Haemogregarina. Although there are currently no reports of cases causing mass mortality of soft-shelled turtles and turtles, with the development of the soft-shelled turtle and turtle breeding industry, if attention is not paid, it is very likely to become a seriously harmful disease.

(3) Symptoms

At present, the infection intensity is not yet high, with the highest being only 19.7%, so no symptoms can be seen externally. From stained blood smears, it can be seen that the infected red blood cells are often packed with Haemogregarina, the nucleus of the red blood cell is pushed to one side, and the cell is severely swollen and deformed, losing its normal physiological function; especially when Haemogregarina undergoes schizogonic proliferation in the red blood cells, it causes massive disintegration of red blood cells, and many immature red blood cells appear in the peripheral blood, which is a compensatory hyperplasia. Many pseudopod-like protrusions can often be seen on the surface of white blood cells, indicating an enhancement of their physiological activity.

(4) Diagnosis

Take blood from diseased soft-shelled turtles and turtles for smears, stain with Giemsa stain or haematoxylin and eosin, and examine under a microscope.

(5) Preventive Measures

(1) Remove excess mud from the bottom of the pond and disinfect it.

(2) If fish leeches are found parasitizing on the body surface of soft-shelled turtles and turtles, promptly use the pith of an old loofah to absorb enough pig blood, and after the blood coagulates, place it in the pond to trap the fish leeches, and crush the fish leeches to death (see prevention and treatment of fish leech disease for details).

(6) Treatment Methods

No research has been carried out yet.