José Divino Lima

Sporogony and experimental transmission of Babesia equi by Boophilus microplus

Abstract The development of Babesia equi in salivary glands of adult female Boophilus microplus was observed under a light microscope using semithin sections stained with toluidine blue. Engorged nymphs were obtained from splenectomized foals experimentally infected with B. equi. As adults, they were then fed on rabbits for 5 days and the salivary glands of manually collected individuals were removed at intervals of 24 h. Sporozoites were found in type III granular acini cells between the 2nd and 5th days following feeding on the rabbits. Sporoblasts and sporozoites were observed in the same or adjacent acini cells in all the glands examined. The formation of the sporozoites occurred following the multiple division of the sporoblasts through a process of radial budding from the periphery of bodies resulting from multiple fission. Sporozoites were detected in smears of adult males stained with Giemsa, between the 2nd and 5th days following feeding by the ticks. Adults of B. microplus, fed during the nymphal phase on foals with patent parasitemia, transmitted sporozoites of B. equi to a splenectomized foal. The role of B. microplus in the transmission and epidemiology of B. equi is discussed.

OUTBREAK OF CRYPTOSPORIDIOSIS IN DAIRY GOATS IN BRAZIL

An outbreak of cryptosporidiosis is reported among 22 suckling kids aged one to two weeks which were maintained for experimental purposes at the veterinary hospital of the University of Minas Gerais. They were divided into three groups. Group A consisted of 10 animals with acute diarrhoea; initially their faeces were pasty but later they were excreted in watery streams. The animals were treated with gentamicin and fluid therapy but did not respond to treatment and died within a week. Postmortem examination revealed liquid intestinal contents, enlarged mesenteric lymph nodes, and hyperaemia and haemorrhage were observed in the final third of the small intestine of some of the animals. Of the 10 animals in group B four had diarrhoea and six were normal; postmortem examination showed that the macroscopic changes were similar to those observed in group A. Three of the animals with diarrhoea had a massive Cryptosporidium infection in the final third of the small intestine, caecum and colon. Four of the six normal animals had a moderate Cryptosporidium infection in the same organs. The two kids in group C died; they had pasty faeces, and there were many Cryptosporidium oocysts in the faecal smears.

Ultrastructure of sporogony in Babesia equi in salivary glands of adult female Boophilus microplus ticks

Abstract The development of Babesia equi was studied in the salivary glands of adult female ticks, Boophilus microplus, using a transmission electron microscope (TEM). Engorged nymphs were obtained from splenectomized foals experimentally infected with B. equi and fed in the adult phase for 5 days on rabbits. Sporogony in B. equi involves the development of sporoblasts and sporozoites, which form from finger-like projections on the surface and through radial budding. Mature sporozoites (2.0 × 1.1 μm), typically pyriform, showed a polar ring, rhoptries, micronemes, nuclei, and mitochondria, and a high concentration of free ribosomes were observed from the 2nd day of the ticks, feeding on the rabbits. In general, sporogony of B. equi in the salivary glands of B. microplus showed similarities to the development of this parasite in species of Hyalomma, although with some significant differences in the sporozoites dimensions. The results of this study indicate that B. equi is capable of multiplying in the salivary glands of adult female B. microplus, forming sporozoites with specialized organelles characteristic of the invasive form, and suggest that B. microplus can act as a natural vector of B. equi in endemic areas where there is no other probable source of infection or where it is the only tick species present on horses.

Development of an enzyme-linked immunosorbent assay for detection of IgM antibodies to Babesia bigemina in cattle.

A crude antigenic preparation of Babesia bigemina was used to develop an ELISA for the detection of IgM antibodies. Optimal dilutions of the antigen, using positive and negative reference sera, were determined by checkerboard titrations. Negative sera from cattle imported from tick-free areas, serum samples collected from infected B. bigemina cattle were used to validate the test. The specificity was 94% and sensitivity of the Elisa 87.5%. Sera from 385 cattle deriving from areas free from tick-borne diseases, which were submitted to a preimmunization process, were screened by this technique. The Elisa detected seroconversion on the 14th day post-inoculation in animals either infested with Boophilus microplus ticks (infected with B. bigemina), or inoculated with B. bigemina infected blood. Antibody titers decreased after day 33; however, all animals remained positive until the end of the experiment (124 days). The ELISA described may prove to be an appropriate serological test for the detection of IgM antibodies against B. bigemina.

Ultrastructure of Babesia equi trophozoites isolated in Minas Gerais, Brazil

A transmission electron microscope study was carried out on Babesia equi obtained from a splenectomized horse, from the municipality of Santa Luzia, Minas Gerais, Brazil. The isolate was inoculated into two splenectomized foals (1.05 x 1010 parasitized erythrocytes by B. equi). Trophozoites have a single membrane in direct contact with the cytoplasm of the red blood cells, a prominent nucleus, well-developed rough and smooth endoplasmic reticulum, numerous free ribosomes and small food vacuoles. B. equi trophozoites have a cytostome and a long tubular feeding structure in direct contact with the blood plasma.

ENDOGENOUS DEVELOPMENT OF EIMERIA MINASENSIS IN EXPERIMENTALLY INFECTED GOATS

The endogenous development of Eimeria minasensis was studied in 9 coccidia-free goat kids inoculated with 105 sporulated oocysts/kg body weight. Kids were killed 4, 7 (2 animals), 10, 13, 16, 18, 19, and 22 days after inoculation (DAI). In tissue sections of the intestines stained with hematoxylin and eosin and examined by light microscopy, 2 generations of meronts, gamonts, gametes, and oocysts were found. The first generation of meronts developed in cells deep in the lamina propria of the jejunum and ileum. Mature giant meronts (299.4 × 243.8 µm) found 16 DAI were visible to the naked eye and contained a large number of crescent-shaped merozoites. The second generation of meronts developed in the epithelial cells of crypts of the ileum and above the host cell nuclei. Mature meronts (11.5 × 10.1 µm) with 18–28 comma-shaped merozoites were first seen 16 DAI. Gametogenesis took place in epithelial cells of the crypts and villi of the terminal part of the ileum, cecum, and colon. Macrogametes (27.8 × 17.6 µm), mature microgamonts (21.3 × 17.0 µm), microgametes, and oocysts (30.5 × 19.4 µm) were found 19 DAI. Sexual stages were below the host cell nucleus.

Ultrastructure of endogenous stages of Eimeria ninakohlyakimovae Yakimoff & Rastegaieff, 1930 Emend. Levine, 1961 in experimentally infected goat

The ultrastructure of endogenous stages of Eimeria ninakohlyakimovae was observed in epithelial cells of cecum and colon crypts from a goat experimentally infected with 2.0 x 10(5) oocysts/kg. The secondary meronts developed above the nucleus of the host cell. The nucleus first divides and merozoites then form on the surface of multinucleated meronts. Free merozoites in the parasitophorous vacuole present a conoid, double membrane, one pair of rhoptries, micronemes, micropore, anterior and posterior polar ring, a nucleus with a nucleolus and peripheral chromatin. The microgamonts are located below the nucleus of the host cell and contain several nuclei at the periphery of the parasite. The microgametes consist of a body, a nucleus, three flagella and mitochondria. The macrogamonts develop below the nucleus of the host cell and have a large nucleus with a prominent nucleolus. The macrogametes contain a nucleus, wall-forming bodies of type I and type II. The young oocysts present a wall containing two layers and a sporont.