Isolation and molecular characterization of Toxoplasma gondii from chickens and ducks from Egypt.

The prevalence of Toxoplasma gondii in free range chickens is a good indicator of the prevalence of T. gondii oocysts in the environment because chickens feed from the ground. In the present study, prevalence of T. gondii in 121 free range chickens (Gallus domesticus) and 19 ducks (Anas sp.) from a rural area surrounding Giza, Egypt was assessed. Blood, heart, and brain from each animal were examined for T. gondii infection. Antibodies to T. gondii, assayed with the modified agglutination test (MAT), were found in 49 (40.4%) chickens in titers of 1:5 in 11, 1:10 in four, 1:20 in four, 1:40 in eight, 1:80 in 10, and 1:160 or more in 12 chickens. Antibodies were found in three ducks each with a titer of 1:80. Hearts and brains of seropositive (MAT > or = 1:5) chickens and ducks were bioassayed in mice. Additionally, hearts and brains of seronegative (MAT<1:5) animals were bioassayed in T. gondii-free cats. T. gondii was isolated from 19 of 49 seropositive chickens (one with a titer of 1:5, two with a titer of 1:20, one with a titer of 1:40, five with a titer of 1:80, three with a titer of 1:160, and seven with a titer of > or = 1:360). One cat fed tissues pooled from 15 seronegative chickens shed T. gondii oocysts, while two cats fed tissues of 34 seronegative chickens did not shed oocysts. T. gondii was isolated from one of the seropositive ducks by bioassay in mice. The two cats fed tissues from 16 seronegative ducks did not shed oocysts. Genotyping of 20 chicken isolates of T. gondii using the SAG 2 locus indicated that 17 isolates were type III and three were type II. The duck isolate of T. gondii was type III. The mice inoculated with tissue stages of all 21 isolates of T. gondii from chickens and ducks remained asymptomatic, indicating that phenotypically they were not type I because type I strains are lethal for mice. Infections with mixed genotypes were not found.

Prevalence of Toxoplasma gondii antibodies in sera of turkeys, chickens, and ducks from Egypt.

Sera from 173 turkeys, 108 chickens, and 48 ducks from Giza, Egypt, were tested for the presence of anti-Toxoplasma gondii antibodies by means of the modified agglutination test using mercaptoethanol and formalin-fixed tachyzoites. The prevalence of anti-T. gondii antibodies (>1:25) among turkeys, chickens, and ducks was 59.5%, 47.2%, and 50%, respectively.

Effect of Fasciola gigantica somatic extracts and excretory/secretory products on superoxide production by activated neutrophils.

Somatic extracts and excretory/secretory (ES) products from Fasciola gigantica suppress the release of toxic oxygen intermediates by activated sheep neutrophils. At the concentrations used both the somatic extracts and ES products had no effect on neutrophil viability and in both cases the inhibitory effect was reversible. In the somatic extracts, heating or treatment with trypsin destroyed the inhibitory effect. However, the ES products contained at least two immunomodulatory factors. One was less than 10 kDa, the other greater than 50 kDa and both factors were heat and trypsin stable. By acting locally and only causing temporary inhibition of neutrophil function F. gigantica can protect itself from immune mediated oxidative damage without compromising the host's response elsewhere.

Isoenzyme activities of different strains of Cryptosporidium parvum.

Different isoenzyme activities have been assayed in three strains of Cryptosporidium parvum, C1 (C. parvum from infected calves, UK), C2 (C. parvum from infected calves, Egypt) and C3 (C. parvum from infected goats, Egypt). The electrophoretic variations of five enzymes; lactate dehydrogenase (LDH), glucose phosphate isomerase (GPI), hexokinase (HK), malate dehydrogenase (MDH) and glutamate dehydrogenase (GLDH) were compared among the three different isolates using native polyacrylamide gel-electrophoresis. LDH showed an identical pattern in the three isolates. GPI showed two different bands in C3 and C1, with both bands present in C2. HK activity showed a weak band in C1 but no reaction was detected with C2 and C3. Malate dehydrogenase (MDH) showed no reaction in C1, but similar bands in C2 and C3. Glutamate dehydrogenase (GLDH) showed two different patterns, C2 and C3 had one pattern and C1 showed additional zones of reaction. Rat liver homogenate was run at the same time as the parasite extracts as a positive control. This investigation suggests that GPI, HK and GLDH could be used to characterise different Cryptosporidium isolates.

Pig, donkey and buffalo meat as a source of some coccidian parasites infecting dogs.

Experimental infection of dogs with meat samples (oesophagus, heart and diaphragm) from each of 105 pigs, 11 donkeys and 17 Egyptian water buffaloes indicated that they contained the infective stages of some coccidian parasites of dogs. The dogs which were fed pig meat shed in their faeces Isospora ohioensis, I. canis oocysts and Sarcocystis miescheriana sporocysts after prepatent periods of 3-5, 4-7 and 9-10 days, respectively. The dogs which were fed donkey meat excreted only I. ohioensis oocysts and Sarcocystis bertrami sporocysts after prepatent periods of 3 and 11 days, respectively. However, the dogs which were fed buffalo meat shed in their faeces I. ohioensis, I. canis and Hammondia heydorni oocysts with prepatent periods of 1, 1 and 7 days, respectively.

Seroprevalence of Toxoplasma gondii in Egyptian donkeys using ELISA.

A serological survey of Toxoplasma gondii was conducted using ELISA on 121 sera from adult donkeys from Monofia Province, Egypt. Antibodies to T. gondii were found in 65.6% of 121 donkeys.

Observations on the use of ELISA for detection of Babesia bigemina specific antibodies.

An indirect enzyme-linked immunosorbent assay (ELISA) was evaluated to study the cause of the high level of background reactions which hinders the application of ELISA as a field diagnostic test for Babesia bigemina. Different blockers to improve the specificity of the ELISA were compared. THe use of soya milk (25%), gelatin (2.5%) and chicken serum (2%) did not significantly improve the specificity of the test. It was noted that the presence of fibrinogen contributed to the positive ELISA results more than the presence of B. bigemina specific antigen. This conclusion was confirmed by testing bovine fibrinogen as a host protein antigen in ELISA which strongly responded against B. bigemina positive control sera. It is suggested that application of ELISA for B. bigemina is still unreliable until a more purified Babesia-specific antigen or specific monoclonal antibodies are available.

Camel (Camelus dromedarius) and sheep (Ovis aries) meat as a source of dog infection with some coccidian parasites.

Experimental infection of dogs with camel (Camelus dromedarius) meat resulted in infection of the dogs with Isospora canis, Hammondia heydorni and Sarcocystis cameli. The dogs fed sheep (Ovis aries) meat passed oocysts of Isospora canis, Isospora ohioensis and sporocyts of Sarcocystis spp. Extraintestinal stages were detected in the intestinal lymph node of a rabbit killed 4 days following inoculation with Isospora ohioensis oocysts. Dogs fed the rabbit (killed 4 days after inoculation with I. ohioensis) passed I. ohioensis oocysts in their faeces 8 days post-infection.