Humoral immune response and hematologic evaluation of pregnant Jersey cows after vaccination with Anaplasma centrale.

The main objective of this work was to evaluate the safety of an Anaplasma centrale vaccine in pregnant pure bred Jersey cows selected from a herd located at Miranda State, Venezuela. Ten cows of 3-5 months of gestation were chosen and previous vaccination all cows were tested for Anaplasma antibodies by the indirect immunofluorescence assay (IFA), so only seronegative cows were included in the group, and for blood parameters, rectal temperature, and pregnancy. Selected cows were vaccinated intramuscularly with 1ml of an A. centrale live vaccine which had 10(8) A. centrale per ml. Over the next 2 months cows were checked weekly for hematological parameters and Anaplasma antibodies, and then for the next 2 months these evaluations were performed monthly. Among the values monitored were: A. centrale parasitemia, hematocrit, hemoglobin, and white blood cells (WBCs) (neutrophil, lymphocyte and eosinophil counts). Levels of Anaplasma antibodies were measured by IFA. Anaplasma were observed for the first time in blood films of two vaccinated cows at 14 days post-vaccination (PV), 6 out of 10 cows were A. centrale positive at 30 days PV, and all cows were A. centrale positive at 42 days PV. A. centrale often showed low parasitemia, 1-3%. Anaplasma antibodies were detected at day 14 PV in all vaccinated cows with a mean group titre of 360 (range: 80-1280). All vaccinated cows showed few changes in their hematologic parameters or in rectal temperature, and all gave birth to healthy calves. In conclusion, adult pregnant cows were safely vaccinated with this live A. centrale vaccine, which may help to develop a cross-protective immunity against field strains of A. marginale.

Future perspectives on veterinary hemoparasite research in the tropics at the start of this century.

This paper has two main objectives: (1) to promote discussion about the future of veterinary hemoparasite research at the start of the twenty-first century and the third millennium, and (2) to stimulate young students to start research on parasitology, in particular in the field of veterinary tropical diseases. It is well known that in the twenty-first century human society will be challenged by several major problems resulting from the demographic explosion, since the Earth's population for the year 2020 will reach 8.5 billion, or 10 billion for the year 2050, as long as the birth rate decreases from 2.8 births per woman today to 2.0 by the year 2030 (data released by the U.N. Population Fund, 1998). Since the food production rate, either from plant or animal origin, is lower than the human birth rate, the challenge ahead will be to produce enough food for ten billion people. Consequently, to deal with this problem, especially in developing nations, it is proposed: (1) to give priority status to scientific research in the agriculture and animal fields; (2) to concentrate financial support and efforts for research especially on hemoparasitic diseases (i.e., babesiosis, anaplasmosis, cowdriosis, ehrlichiosis, and trypanosomosis), in particular to apply biotechnology techniques to those animal diseases; and (3) to grant a better role to studies on veterinary and medical parasitology in universities of the Americas and Europe, since in these universities parasitology is currently considered a secondary subject.

Seroprevalence of Toxoplasma gondii in goats from arid zones of Venezuela.

A total of 438 sera were collected from dairy goats on 10 farms located around Aregue Village, Lara State, Venezuela and evaluated for Toxoplasma gondii antibodies using the indirect hemagglutination assay. Antibodies to T. gondii were found in 26 of 386 > or =4-yr-old does from 8 of 10 farms; antibody titers were 1:64 (10 does), 1: 256 (3 does), 1:512 (5 does), 1:1,024 (1 doe), and 1:4,096 (7 does). Antibodies were not found in 52 <12-mo-old goats.

Levels of natural resistance to Boophilus microplus (Acari: Ixodidae) in Carora breed bulls.

Boophilus microplus infestation is one of the most serious limitations to cattle industry in tropical regions, even though bovines show natural resistance to ticks. This resistance was evaluated in Cross-bred Carora Bulls (CCB) a tropicalized dairy breed from Venezuela. Seven CCB were experimentally infested with B. microplus larvae, "Mozo" strain, they were considered tick-naive because they had never been infested with ticks. The mean inoculum size applied on each bull was 6,477 larvae. After life cycle was completed adult female body weight (BW), egg mass weight (EW), egg hatching rate (%EH), and reproductive index (RI) were recorded. Results revealed a high variability in the levels of resistance to B. microplus. Thus, one animal showed greater resistance (Dunnett, p < 0.05) for the analyzed parameters in contrast with three non-resistant bulls. The others had moderate resistance. The trait "resistance" should be included together with other traits often used in genetic selection of cattle.

Incidence and intensity of Babesia spp. sporokinetes in engorged Boophilus microplus from a dairy herd in Venezuela.

The objective of this study was to determine the incidence and intensity of Babesia spp. sporokinetes in hemolymph of engorged females (EF) Boophilus microplus monthly detached from two herds of a local dairy breed of cattle named Carora breed. The experimental herds were located in 2 ranches, 45 km apart, having different management of tick control (TC). Proper methods of TC were commonly used at ranch "A," whereas ineffective methods were used at ranch "B," Babesia spp. sporokinetes were diagnosed in EF B. microplus by microscopic exam of tiny smears of hemolymph stained with Giemsa. A total of 537 smears were checked, and 108 were positive to Babesia spp. (20.1%). The incidence of Babesia spp. was higher (p < 0.01) in ranch "B," 22.3%, compared with the value detected in ranch "A," 6.5%. Incidence of Babesia spp. was greater in the dry season (Dec-Apr) compared with the values detected during the rainy season (May-Nov). The intensity of Babesia spp. was 3.43 at ranch "B" (p < 0.01), and 0.32 at ranch "A" during the rainy season. The values detected for intensity kept no correlation with those two seasons, although it is known that the incidence and seroprevalence of bovine babesiosis are greater during the dry season. The importance of these parameters in the epizootiology of bovine babesiosis in Venezuela is discussed.

Perinatal infection with Trypanosoma vivax in a calf in Venezuela.

A case of perinatal infection by Trypanosoma vivax is reported in a 5-hr-old Carora local dairy breed calf. The levels of parasitemia were followed during 15 mo in the infected animal. Similarly, its immune response was monitored during 4 mo by the indirect fluorescent assay. Trypanosoma vivax was observed in Giemsa-stained blood films collected during the first 4 mo of life from the infected calf. Positivity was detected on days 0, 35, 80, and 125 after first sampling. Antibodies against T. vivax were detected each time the indirect fluorescent assay was performed, showing low titers (1:80-1:160). The importance of a congenital route of transmission for this Trypanosoma species in cattle herds, on a continent where Glossina spp. flies are absent, is discussed.

Orbital hydatid cyst of Echinococcus oligarthrus in a human in Venezuela.

This study reports the first known case of human hydatid disease caused by the larval stage of Echinococcus oligarthrus. The patient, a native Venezuelan female, presented a single cyst localized intraorbitally behind the left eye (retroocular), which was discovered by computed tomography. The cyst was removed by surgery, and after parasitological studies it was identified as an E. oligarthrus hydatid cyst. This is also the first case of intraorbital hydatid cyst in humans in Venezuela.

Antigen beads: a novel approach for the delivery of a soluble Anaplasma immunogen.

An important consideration in the development of effective immunization regimens against bovine anaplasmosis is the optimization of vaccine delivery systems. This report describes the formulation of proteinaceous antigen-containing spheres derived from supernatant fluids of Analplasma marginale cultures. The antigen beads were designed for use as potential dispersal agents for a soluble Anaplasma immunogen. Immunospecificity assays demonstrated that A marginale antigen was located on the surfaces of individual antigen beads. Use of Anaplasma antigen beads with a potent adjuvant, such as saponin, was proposed.

Experimental life cycle of Ascaridia columbae in intravenously infected pigeons, Columba livia.

The fate and routes of migration of infective larvae of Ascaridia columbae were studied in intravenously (i.v.) infected pigeons. Larvae were able to complete a trachael migration, and arrived at the small intestine where they established a patent infection. Granulomas were observed and histopathologically described in the lungs of i.v. infected birds.