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This study was undertaken to detect Trypanosoma evansi infection in clinically ill cattle, buffaloes and horses that were suspected of 'surra' infection. Various diagnostic tests were utilized in order to assess the prevalence of infection in the clinically ill and 'suspected' animals. Animals in the Eastern Region of India were systematically studied for T. evansi infection, which had not been tested for previously. Examination of Giemsa-stained blood smears detected 5.3%, 9.4% and 40.6% infections; the mouse inoculation test detected 18.4%, 15.6% and 46.9% infections whereas an in-house ELISA detected anti-trypanosomal antibodies in 42.1%, 43.8% and 65.6% infections in clinically ill buffaloes, cattle and horses, respectively. It can be concluded that T. evansi is prevalent in cattle, buffaloes and horses in the Eastern Region of India.

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Diagnosis of Trypanosoma evansi infection in a horse stable of Eastern Region of India on the basis of examination of Giemsa stained blood smears have been done. A high percentage (12.74%) of horses of this stable was found suffering from T evansi infection. This high prevalence of T evansi in horses, in this area could be considered as an alarming situation which has never been explored previously in horses of Eastern Region of India. After a period of 2 months and 18 days of treatment with quinapyramine sulphate and quinapyramine chloride, reinfection with T evansi in treated horses of this stable were noticed. Clinical signs of affected horses and possible causes of reinfection have been discussed.

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Visceral larva migrans (VLM), caused by Toxocara canis larvae in humans, animals and birds, is now well documented throughout the world. Seven piglets were infected orally with 5 x 104 embryonated eggs and the migration and distribution of T. canis larvae in the tissues were evaluated. After artificial gastric juice digestion, larval yields at necropsy from different organs and muscles on days 1, 3, 7, 15 and 30 post-infection (DPI) revealed 3.05, 0.97, 0.21, 0.13, 0.05, 0.14% recovery from liver, lungs, heart, kidneys, skeletal muscles and brain tissues respectively, with a total of 2486 (4.97%) recovery from all tissues together. The highest number of larvae 1527 (3.05%) was recovered from the liver throughout the period (1-30 DPI), indicating a special affinity of larvae for the liver. Subsequently five mice were each infected orally with 5 g of infected pig liver and, after necropsy on 10 DPI, 20 +/- 3.62, 17 +/- 5.10, 3 +/- 1.26, 12 +/- 3.92 and 30 +/- 5.69 larvae were recovered from liver, lungs, heart, brain and muscles, respectively. Thus, primarily, the migratory potential and adaptation of T. canis larvae in porcine tissue was examined and, subsequently, their establishment in the second paratenic host, the mouse, has been successful. No influence of host sex on the migratory potential of T. canis larvae was observed. The related pathology caused by migratory larvae and its zoonotic significance through the consumption of raw or undercooked pork has been emphasized.

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The western blot analysis for identification of immunogenic proteins in whole cell lysate (WCL) antigens (Ags) prepared from the Trypanosoma evansi of buffalo, horse and cattle origins using hyperimmune sera (HIS) showed 11 immunogenic proteins and naturally T. evansi infected immune sera (IS) of horse detected 19 immunogenic proteins. HIS and IS of horse recognized five common immunogenic proteins of relative molecular weight (M(r)) ranges 61-64, 44-47, 33-34, 25-26 and 14-16 kilo Dalton (kDa). HIS rose against WCL Ags of T. evansi of buffalo origin and immune sera of horse cross reacted with WCL Ags of T. evansi of different host origin. It can be concluded that in comparison to HIS, IS of horse could able to detect more numbers of immunogenic proteins and five common immunogenic proteins in WCL Ages of T. evansi of different hosts origin. The evidence of higher reactivity of IS in comparison to HIS against T. evansi is being reported for the first time.

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The possible role of the cockroach Periplaneta americana in the transmission of Toxocara canis eggs and larvae via faeces and tissue migration was studied. Cockroaches fed with 3 x 105 and 5 x 105 embryonated eggs were found to harbour viable eggs and larvae from days 1 to 5 post-infection (DPI). At necropsy on 5 DPI, eggs and larvae were also recovered from the rectal contents but not from the tissues of cockroaches. In addition patent infections were established in pups fed on infected faeces of cockroaches, with eggs first appearing in the faeces of pups at 38 DPI. Adult worms of T. canis were also recovered at necropsy. Therefore the importance of cockroaches as good mechanical disseminators of ascarid eggs, especially T. canis, is discussed.

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The migration and distribution of Toxocara canis larvae in the tissues of earthworms exposed to 5 x 10(5) infective eggs in soil, as well as the reinfectivity of the larvae in Japanese quail fed with three earthworms, were studied. The average number of larvae recovered from an earthworm gradually declined from 9 +/- 3.21 to 4.5 +/- 2.00 at 4-16 days. No larvae were recovered at Day 20. When compared between three portions of the earthworms' body, the middle part showed the greatest recovery in comparison with the anterior and posterior parts. At necropsy, the average larval burden of quail at 15 days post-infection was 6 +/- 3.60 in the liver and no larvae were recovered from other tissues. The role of the earthworm in relation to paratenism is discussed.

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Migration and distribution of Toxocara canis larvae in the tissues of Japanese quail, infected orally with 5 X 10(3) infective eggs, and the establishment of patent infection from the quails to the definitive host, were studied. Larval yield at necropsy from various tissues and organs of quail varied from 4.72 to 7.54% of the infective eggs inoculated within the period 1-60 days post-infection (PI). The total number of larvae recovered on different days showed a gradual increase. The percent inoculum recovered at necropsy was highest on Day 60. Most of the larvae were found in the liver throughout the period and only a few migrated to other tissues, such as lung, heart, muscle and brain. The establishment of patent infections in the definitive host was studied by feeding the 15-day infected livers of Japanese quail (400 larvae) to Toxocara-free pups. Eggs first appeared in the faeces 38 days post-infection, the mean worm burden at necropsy was 87 and the percentage of infection established was 21.75%. Thus the role of Japanese quail as a paratenic host of T. canis is established.

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The migration and distribution of Toxocara canis larvae in the tissues of Japanese quails, infected orally with 5 x 10(3) infective eggs, were studied, as well as the re-infectivity of these larvae in mice, inoculated with 50 larvae obtained from the liver of these quails. Post-infection, the highest concentrations of larvae were found to be present in the liver of quails while only a few migrated to other tissues like lungs, heart, muscle and brain. The migration and distribution of the larvae in the tissues of mice were studied by necropsy on days 6 and 12 post-infection. On both days the highest number of larvae, 11 and 10, were recovered from the carcase followed by six and seven from the leg muscles and four and eight from the brain, respectively. A few larvae were recovered from the liver, lungs and viscera. This implies that the larvae had a special affinity for the muscle and brain tissue of mice, unlike in the quails. The role of these larvae in relation to paratenism is discussed.

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The migration and distribution of Ancylostoma caninum larvae in the tissues of chickens, infected orally with 1,000 larvae, were studied. Larval yield at necropsy from different organs after digestion with artificial gastric juice revealed a 62.9% recovery four hours after inoculation, followed by a sharp decline to 5.4% at 72 hours. Larvae were found in the heart within four hours, the lungs within eight hours and the liver within 12 to 18 hours but no larvae were recovered from the spleen, kidney or brain. Migration in the muscles of head, neck, thorax and abdomen was detected at 12 hours and was maximal at 36 hours. The establishment of patent infection in the definitive host was studied by feeding infected chicks to hookworm-free pups (one chick/pup) 48 hours, 7 days and 14 days after infection. The mean worm burden at necropsy was highest (15) in the pups fed with chicks 48 hours after infection and was three and nil in the other groups respectively.

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Migration and distribution of Ancylostoma caninum larvae in the tissues of mice orally infected with 1000 larvae, and establishment of patent infection from the mice to the definitive host, were studied. Larval yield from different organs of mice, after digestion with artificial gastric juice, indicated that the highest recovery was at 4 h post-infection (62.8%), and thereafter a slight decline occurred up until 30 days post-infection (51.5%). Migration of larvae to the lungs occurred within 4 h, to the liver within 12 h and into the heart within 24 h. No larvae were recovered from spleen and kidney tissues. From the 9th day onwards larvae were also recovered from the brain. Migration in the muscles of head and neck occurred within 4 h, in the thoracic and abdominal muscles at 24 h and in lumbosacral and leg muscles at 48 h. The establishment of patent infections in the definitive host was studied by feeding the orally- and percutaneously-infected mice to hookworm-free pups at 10 and 30 days post-infection. The mean necropsy worm burden in the pups fed with the orally-infected mice was comparatively higher than in the pups fed cutaneously-infected mice.

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Infectivity of A. caninum in dogs inoculated with 500 larvae by different routes (percutaneous, subcutaneous, intravenous, per os, through a stomach tube and foot pad) was studied by ascertaining the worm burden at necropsy 21-27 days post-infection. Infection through foot-pads yielded the maximum number of worms. The percentage of worm establishment using foot-pad inoculation was 73.8%, followed by subcutaneous (49.0%), percutaneous (45.0%) and per os (35.0%) routes. These results show that active penetration of the larvae through skin and particularly foot-pad is the most favourable mode of infection of dogs.

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The effect of restricted medication with lasalocid sodium on the development of acquired immunity against Eimeria tenella was evaluated. The medication was allowed for all or part of 6-day test period (one day before until 4 days after infection). The parameters used for such evaluations were lesion score, caecal, bursal and splenic weights. The optimum treatment time for the drug was clearly indicated by lesion score which was very low when the medication was initiated 1 day before until 1 day after inoculation, but only partly effective if given on Day 2 post-inoculation. The challenge with higher doses on 14th day of immunizing infection revealed a reverse picture where the higher lesions were recorded by the groups where medication was started earlier than the delayed treatment groups. This indicates partial interference with the development of immunity in the earlier treatment groups. Birds treated on Day 4 p.i. were not significantly different (P less than 0.05) from the infected unmedicated control group, suggesting no interference in acquired immunity. A correlation was noticed between day of treatment, the lesion score and weight gain of the caecum as well as the spleen. After both immunizing and challenge infections, the bursa did not show any significant variation in weight, whereas the weight of the spleen did vary. The infected unmedicated group and the delayed-treatment groups had a comparatively higher splenic weight than the uninfected unmedicated group of birds.(ABSTRACT TRUNCATED AT 250 WORDS)

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