Incidence of Toxocara vitulorum in Creole calves of Guadeloupe

The 247 calves from 112 Creole cows of Guadeloupe were monitored for Toxocara vitulorum infection from year 2002 to 2005. The cows were in good body condition and the calf growth rate was 880g/d on average. The overall prevalence of infection was estimated to 0.77 [0.72; 0.83]. The faecal egg count peaked 49 days after calf birth, and then decreased. No clinical symptom related to T. vitulorum infection was observed, and no effect on the calf growth rate was shown. It was concluded that, despite the high prevalence of T. vitulorum, the production loss remains under the level of detection, and no drenching is needed for well-fed animals.     

Toxocara vitulorum in beef calves kept on effluent-irrigated pastures in Zimbabwe

Faeces from 20 calves aged 13 +/- 5 days were examined for Toxocara vitulorum eggs fortnightly for a period of 20 weeks. The age of calves when eggs were first detected varied from 24 to 110 days (mean 41 +/- 20 days). The mean egg count varied from 257 to 19,821 g-1 of faeces with a highest count of 68,400. The patency period of T. vitulorum lasted from 14 to 112 days (mean 65 +/- 30 days). None of the calves showed clinical signs of illness.     

Morphological observation of Toxocara vitulorum found in Japanese calves.

Between 1982 and 1988, ascarid nematodes were found in the feces of Japanese calves in Kyushu and Okinawa districts. Seven males and 21 females of the ascarids were observed morphologically for identification of species. Male and female ascarids were 15.64 (14.0-18.0) cm and 25.75 (16.5-34.0) cm in average length, respectively. Eggs were 81.6 microns and 71.8 microns in large and small diameters, respectively. The body of ascarids was translucent and soft. The boundary between the enlabium and prelabium of lip was clearly visible and the esophageal ventriculus was also observed. The vulva was situated at a distance of about 1/7 approximately 1/9 of body length from the anterior end of body. The surface of egg shell was relatively smooth, without rugose albuminous coat. These morphological features coincided with those of Toxocara vitulorum.     

Toxocara vitulorum in the milk of buffalo (Bubalus bubalis) cows

The duration of excretion of Toxocara vitulorum larvae in the milk of buffalo cows determines the optimum time for treating calves. Studies on 10 cows showed that a few larvae occur in the colostrum of some cows before the calf has suckled, but most are present from the day after calving and for a further five days. From day 9 onwards, very few larvae were found in the milk. The total number of larvae found was comparable with the number of adult parasites collected from the calves of cows with similar histories. The larvae were 1254 +/- 60 microns long and 36 +/- 6.7 microns in diameter at the ventriculus, figures which are substantially different from some published results.     

Biology and pathophysiology of Toxocara vitulorum infections in a rabbit model.

Ten female New Zealand rabbits were infected via stomach intubation with eggs of Toxocara vitulorum at a dosage of 10 embryonated eggs per gram of body weight on Days 0, 35 and 72. Ten or 4% of the administered parasites passed in the feces during the 3 days following the first or second infection, but 32% after the third infection. Many larvae were passed in the third infection, but not in the first or second. Tissue parasite yields were 4.1% on Day 5, 2% on Day 15, 0.8% on Day 30, 0.1% on Day 65 and 0.06% on Day 101. Five hundred and ninety-three larvae were recovered from liver, 243 from lungs and 0 from muscles on Day 5; 282 from liver, 138 from lungs and 21 from muscles on Day 15; 151 from liver, 21 from lungs and 50 from muscles on Day 30; 0 from liver, 26 from lungs and 15 from muscles on Day 65; 0 from liver, 0 from lungs and 9 from muscles on Day 101. No larvae were found in other tissues. The size of the muscle larvae at 30, 65 and 101 days indicated that the parasites did not develop beyond the infective stage and suggested that they were probably hypobiotic organisms. Erythrocytes, packed cell volume and monocytes decreased, but eosinophils and basophils increased, after each infection. Serum enzyme levels indicated that liver damage occured only after the first infection, but muscle injury occurred after each infection and was increasingly more precocious after each infection.     

The egg production of Toxocara vitulorum in Asian buffalo (Bubalus bubalis)

The egg production of Toxocara vitulorum in Asian buffalo has been studied. Eggs were first present in the faeces of calves when they were 22.3 +/- 1.6 days old. In calves treated with pyrantel when 3 days old, the age at first patency was extended by 3.5 days indicating that there was no pre-natal transmission. Calves on only half the milk of the cow had a significantly longer prepatent period of 27.7 +/- 2.2 days. The peak egg output occurred in calves 35.7 +/- 2.6 days old and had a duration of 5.5 +/- 2.5 days with 98,000 +/- 63,700 eggs g-1 of faeces. The duration of the patent period was 35 +/- 12 days. The average lengths of populations of mature female parasites from different hosts at the time of peak egg output or older, ranged from 15.0 to 31.0 cm and was correlated with those of the males in the same populations (10.6-20.4 cm). The size of females was not affected by intraspecific competition. The proportion of males in the populations was 0.39 +/- 0.11. The egg output per female per day at the peak was 110,000 +/- 58,000 and was correlated with the size of the females at autopsy, but the egg output per female per day at the time of autopsy was lower and was not correlated, so it was concluded that the drop in egg counts was the result of reduced fecundity. The fertility of the eggs from faeces was greater than 92% throughout.(ABSTRACT TRUNCATED AT 250 WORDS)     

Predatory activity of Pochonia chlamydosporia fungus on Toxocara (syn. Neoascaris) vitulorum eggs

Toxocara (Neoascaris) vitulorum is a gastrointestinal nematode parasite of young ruminants, responsible for high mortality rates in parasitized cattle and buffalo calves. The objective of this work was to compare the predatory capacity under laboratory conditions of four fungal isolates of the nematophagous fungus Pochonia chlamydosporia (VC1, VC4, VC5 and VC12) on T. vitulorum eggs in 2% water-agar (2% WA). T. vitulorum eggs were plated on 2% WA Petri dishes which contained cultured fungal isolates and control plates without fungi. After 10 and 15 days one hundred eggs were removed and classified according to the following parameters: type 1, biochemical and physiological effect without morphological damage to the eggshell, type 2, lytic effect with morphological alteration of the eggshell and embryo and type 3, lytic effect with morphological alteration of eggshell and embryo in addition to hyphal penetration and internal egg colonization. The fungal isolates were effective in the destruction of T. vitulorum eggs presenting the type 3 effect at 10 and 15 days after contact with the fungus. No nematophagous fungi were observed in the control group during the experiment. There was no variation in the predatory capacity of the fungal isolates (P?>?0.01) at the intervals of 10 and 15 days. These results indicate that P. chlamydosporia (VC1, VC4, VC5 and VC12) negatively influenced the development of T. vitulorum eggs and can be considered a potential candidate for the biological control of nematodes.     

Humoral immune response of water buffalo monitored with three different antigens of Toxocara vitulorum

Humoral immune response of water buffalo naturally infected with Toxocara vitulorum was monitored using three different antigens of this parasite in serum and colostrum of buffalo cows and calves. Soluble extract (Ex) and excretory/secretory (ES) larval antigens and perienteric fluid antigen (Pe) of adult T. vitulorum were used to measure the antibody levels by an indirect ELISA. Serum of 7-12 buffalo cows for the first 365 days and colostrum of the same number of buffalo cows for the first 60 days of parturition, and serum of 8-10 buffalo calves for the first 365 days after birth were assayed. The ELISA detected antibodies against all three T. vitulorum antigens in the colostrum and serum of 100% of buffalo cows and calves examined. The highest antibody levels against Ex, ES and Pe antigens were detected in the buffalo cow sera during the perinatal period and were maintained at high levels through 300 days after parturition. On the other hand, colostrum antibody concentrations of all three antigens were highest on the first day post-parturition, but decreased sharply during the first 15 days. Concomitantly to the monitoring of immune response, the parasitic status of the calves was also evaluated. In calves, antibodies passively acquired were at the highest concentrations 24 h after birth and remained at high levels until 45 days coincidentally with the peak of T. vitulorum infection. The rejection of the worms by the calves occurred simultaneously with the decline of antibody levels, which reached their lowest levels between 76 and 150 days. Thereafter, probably because of the presence of adults/larvae stimulation, the calves acquired active immunity and the antibodies started to increase slightly in the serum and plateaued between the days 211 and 365. All three antigens were detected by the serum antibodies of buffalo calves; however, the concentration of anti-Pe antibody was higher than anti-EX and anti-ES, particularly after 90 days of age. By conclusion, the buffalo cows develop immunity and keep high levels of antibodies against T. vitulorum-Ex, ES and Pe antigens and these antibodies are transferred to their calves through the colostrum. This passively acquired immunity does not protect the calves against the acquisition of the infection, but these antibodies, passively or actively acquired, may have an important role during worm rejection by the calves and prevention of intestinal reinfection.     

The extraparasitic life cycle of Toxocara vitulorum in the village environment of Sri Lanka

The extraparasitic life cycle of Toxocara vitulorum of buffalo in the villages of Sri Lanka is related to observations on buffalo behaviour, experimental studies on the development and persistence of the eggs in soil and in wallows and the presence of eggs in village locations. Calf faeces on soil were rapidly incorporated by insect activity and the eggs developed only slightly slower than in the laboratory. Some infective eggs persisted 3–4 cm deep for 17 months, finally dying during a prolonged hot, dry period. Eggs in a wallow developed intermittently over 16 months as it was flushed with rain water, and eventually died when the wallow dried out. When infected faeces were placed in water, decomposition caused some material to rise to the surface and eggs developed. In villages, eggs are ubiquitous where young calves are kept but survive best where there is moisture and shade around animal pens and wallows. Cows and calves acquire infection from infective eggs in wallow water, soil and pasture, while calves may also be infected from contamination on the udder and teats of the cow. The larvae resulting from this infection do not mature until the infection is passed to the calf through the milk of the cow. At least 72% of village calves have patent infections and current treatment procedures do not reduce the prevalence.The possibility that T. vitulorum is a cause of human visceral larva migrans is discussed.     

An enzyme-linked immunosorbent assay (ELISA) for detection of antibodies against Toxocara vitulorum in water buffaloes

Toxocara vitulorum, a parasite of the small intestine of cattle and water buffaloes, is mainly acquired by calves via the colostrum/milk from infected cows. To understand the development of immune responses in calves, antibody levels to a soluble extract antigen (Ex) from T. vitulorum infective larvae were measured by an indirect ELISA with sera of 15 buffalo calves, which were sampled every 15 days for the first 180 days after birth and 9 buffalo cows during the perinatal period. From all serum samples examined during the first 180 days, antibody level was lowest and highest in calves at 1 day of age before and after suckling colostrum, respectively, suggesting that the origin of antibodies was the colostrum. Immediately after birth, antibody levels in suckled calves remained at high levels until day 15, began to decrease to lower levels between 15 and 30 days and remained relatively stable until 120 days. By comparing the immune responses of these animals with their parasitological status it was considered possible to determine if passively acquired or actively produced antibodies provided protection against the infection. High numbers of T. vitulorum eggs in the feces between 30 and 60 days indicated that passively acquired antibodies did not provide protection against the infection, at least during these first days, and the maximum fecal egg counts during 30-45 days were coincident with decreased antibody levels. Between 60 and 120 days, when serum antibodies were detected at reduced, but stable levels, adult nematodes were expelled from the intestines and no more T. vitulorum eggs were found, suggesting development of acquired resistance. However, the potential and functional protective role of the antibodies against T. vitulorum infection and the process of self-cure requires further investigation.     

Prevalence and clinical impact of Toxocara vitulorum in cattle and buffalo calves in northern Lao PDR

This study was completed to determine the prevalence and distribution of Toxocara vitulorum infection in cattle and buffalo calves and investigate its clinical impact in northern Lao PDR (Peoples Democratic Republic). The results aim to assist decisions on disease control measures that can contribute to increasing cattle and buffalo productivity within smallholder farming systems in tropical areas. A prevalence survey for T. vitulorum in buffalo and cattle calves aged <3 months was conducted between September 2009 and June 2010 in five provinces of northern Lao PDR using a two-stage sampling technique to select 69 villages and 899 calves, with faecal samples collected and examined for T. vitulorum eggs at a local laboratory. At the time of sampling, data on calf morbidity and anthelmintic treatment was also collected. Factors potentially associated with infection and severity of infection were analyzed at univariable and multivariable levels, using T. vitulorum status (positive/negative) and on the positive calves only, faecal egg count levels as outcome variables. The estimated prevalence of T. vitulorum in northern Lao was 22.6 % (95 % confidence interval [CI], 0.17–0.28), and 76.8 % of villages had at least one positive calf. Province was the only significant (p?<?0.05) variable investigated associated with calf infection status. Species (buffalo) was the only variable significantly (p?<?0.05) associated with higher egg per gram of faeces levels among infected calves. Prevalence in calves aged 1–21 days, the reported prepatent period, was 17.5 % (CI 0.11–0.24). Treatment levels were very low (8.2 %) and if treatment occurred it was mostly unsuccessful. The high and wide spread infection of T. vitulorum in cattle and buffalo calves identified in this survey is likely to result in suboptimal cattle and buffalo productivity. Improved management of T. vitulorum infection in cattle and buffalo calves in northern Lao PDR is indicated to reduce potential negative production impacts and enable more efficient development of large ruminant livestock industry as a pathway from rural poverty for smallholder farmers in northern Lao PDR. In addition to quantifying this disease problem in calves, the conduct of this applied participatory research study provided an important opportunity to improve animal health services by increasing the parasite, large ruminant handling and research knowledge and capacity of government animal health staff and farmers.     

Comparative evaluation of IHA and CIEP in the diagnosis of Toxocara vitulorum in pregnant cows and buffaloes

Tropical Animal Health and Production -     

Toxocara vitulorum: treatment based on the duration of the infectivity of buffalo cows (Bubalus bubalis) for their calves

Treatment of buffalo calves (Bubalus bubalis) at different times after birth demonstrated that transmission of Toxocara vitulorum from the cow to the calf via milk occurs in all calves during the first 2 days after birth, decreases to 53% by 6 days, 10% by 8-9 days and 2% from Day 10 onwards. This may be because the larvae are no longer in the milk or because the calf has become resistant to the establishment of a new infection. The result also emphasizes the importance of mammary transmission of the parasite. Against immature parasites the efficacy of pyrantel and levamisole was 97%; febantel was 100% on one farm, only 35% on another; piperazine 42% and thiabendazole 35%. Santonin was ineffective in four calves. Against mature parasites the efficacy of pyrantel was 100%; febantel was 100% on one farm, only 35% on another; oral levamisole 83%; cutaneous levamisole 73%; oxfendazole 89%; and piperazine 57%. Nevertheless, piperazine reduced the infection to levels which were probably not pathogenic. In general, the efficacy against mature parasites was similar to that against immature parasites. Treatment of 10-16-day-old calves with an anthelmintic, which is effective against immature parasites, is recommended. This procedure greatly reduces contamination of the environment and also precludes the pathogenic effect of a large number of immature or mature parasites.     

Anticoccidial activity of the methanolic extract of Musa paradisiaca root in chickens

The study was designed to evaluate the anticoccidial activity of the methanolic extract of Musa paradisiaca root in chickens. The chickens were divided into six groups of 12 chickens each. Each chicken in five groups was infected with 8,000 infective coccidia (Eimeria tenella) oocysts at day 28 of age while one group served as uninfected control. At day 7 post-infection, two chickens remaining in each group were sacrificed for postmortem examination to confirm coccidiosis. Also at day 7 post-infection, each chicken in four infected groups was given graded doses (250, 500 and 1,000 mg/kg b.w.) of the extract or amprolium (conventional drug). Two groups (an infected and uninfected group) did not receive treatment. Parameters used to assess progress of infection and response to treatment included clinical signs typical of coccidiosis, oocyst count per gramme of faeces (OPG) and packed cell volume (PCV). Treatment of previously infected chickens with M. paradisiaca root extract resulted in a progressive decrease in severity of observed clinical signs, marked reductions in OPG and a gradual increase in PCV. In each case, the changes were dose dependent. There was no significant difference in mean OPG and mean PCV of the extract (at 1,000 mg/kg b.w.) and amprolium-treated groups at termination of the study (at day 50 of age). In the acute toxicity study, the extract was found to be non-toxic to the chickens even at the highest dose of 4,000 mg/kg b.w. The results of this study demonstrated that the extract has anticoccidial activity in a dose-dependent manner and at a dosage of 1,000 mg/kg b.w. had similar efficacy with amprolium in the treatment of chicken coccidiosis.     

Detection of antibody to Toxocara vitulorum perieneteric fluid antigens (Pe) in the colostrum and serum of buffalo calves and cows by Western blotting

Toxocara vitulorum, a nematode parasite in the small intestine of cattle and water buffaloes, causes high morbidity and mortality of 1-3 months old buffalo calves. This research evaluated the specific perieneteric antigens (Pe) reactivity of anti-T. vitulorum-Pe antibody (Tv-Pe-Ab) in both immune sera and colostrum from buffalo cows immediately post-partum from buffalo cows. The presence of Tv-Pe-Ab in sera of buffalo newborn calves was also examined at 1 day before and after suckling the colostrum as well as in sera from naturally infected calves at the beginning and peak of the maximum infection and then again during the period of rejection and post-rejection of the parasite. Pe antigens were characterized for Tv-Pe-Ab by SDS-PAGE and Western blot (WB). The SDS-PAGE showed that Pe contained nine protein bands (11, 14, 31, 38, 58, 76, 88, 112 and 165 kDa). All Pe bands were recognized by Tv-Pe-Ab in sera and colostrum of buffalo cows. Only the serum antibodies of buffalo calves at 1 day of age after suckling the colostrum and during the beginning of T. vitulorum infection recognized Pe antigen's nine bands. In contrast, serum antibodies from 1-day-old buffalo calves, taken before suckling colostrum, did not react with any protein band. In suckling calves, which reached peak egg output, rejection and post-rejection stages of the infection, serum Tv-Pe-Ab reactivity with lower molecular weight protein bands (11-76 kDa) was lost and only reactivity with the Pe protein bands of higher molecular weight (88, 112 and 165 kDa) remained.     

Mast cell and eosinophils in the wall of the gut and eosinophils in the blood stream during Toxocara vitulorum infection of the water buffalo calves (Bubalus bubalis)

Toxocara vitulorum is a pathogenic nematode from the small intestine of very young buffalo calves. To understand the development of the inflammatory responses in the wall of the gut, samples of tissues were removed from the duodenum, jejunum and ileum of buffalo calves naturally infected with T. vitulorum during the beginning of the infection, at the peak of egg output, as well as during the periods of rejection of the worms and post-rejection. Two additional control groups of uninfected calves (by anti-helminthic therapy of their mothers and after the birth) were also necropsied on days 30 and 50 after birth. Blood samples were fortnightly collected from birth to 174 days post-birth. Blood smears were prepared and stained with Giemsa for eosinophils. The parasitological status of buffalo calves was evaluated through weekly fecal egg counts (EPG) from 1 to 106 days after birth, which revealed that T. vitulorum egg shedding started on day 11, reached the peak of the infection on day 49 and finally expelled the parasites between days 50 and 85 after birth. In the infected buffalo calves, the mast cell population increased significantly, by two-fold in the mucosa (villus-crypt unit (VCU)) of the duodenum and four-fold in the proximal jejunum; but these increases were statistically significant only at the peak of the infection. Although mast cell numbers increased in the mucosa of the ileum as well as in both the submucosal and muscle tissues of the duodenum, proximal jejunum and ileum, the data was not significantly different from the controls. Eosinophil numbers increased in the mucosa of the duodenum (two-five times higher than the control) and proximal jejunum (three-five-fold) during the period of the infection (beginning, peak and rejection). The relative numbers of eosinophils increased in the blood stream from the second to the seventh week. In conclusion, T. vitulorum infection elicited mastocytosis and tissue eosinophilia in the duodenum and proximal jejunum, as well as eosinophilia in the blood stream, during the beginning, at the peak and during the rejection of the worm. After the rejection of the worms, the numbers of these cells returned to normal levels suggesting that these cells may have a role in the process of rejection of T. vitulorum by the host.     

浅析犊牛新蛔虫病防治

犊牛新蛔虫病是由异尖科新蛔虫属犊新蛔虫寄生于初生犊牛（黄牛和水牛）的小肠内，引起犊牛肠炎、下痢、腹部膨胀和腹痛等症状的一种寄生虫病。该病分布极广，我省流行较为严重，初生犊牛感染轻则影响生长发育，重则引起死亡。近年来随着我州肉牛、奶牛产业化进程的推进，特别是水奶牛的开发，水牛冻精改良步伐的加快，杂交犊牛存栏数增加，摩本杂交犊牛增加很快，该病发病率有所增加，给肉牛、奶牛产业化发展造成很大影响.     

Efficacy of selamectin against experimentally induced and naturally acquired infections of Toxocara cati and Ancylostoma tubaeforme in cats

The efficacy of selamectin against experimentally induced and naturally acquired infections of adult ascarids (Toxocara cati) and adult hookworms (Ancylostoma tubaeforme) was evaluated in five controlled studies in cats. Two studies evaluated the efficacy of selamectin against both ascarid (natural or induced) and hookworm (induced) infections; two studies evaluated the efficacy of selamectin against single natural infections of T. cati or A. tubaeforme; and the fifth study evaluated the efficacy of selamectin against induced infections of A. tubaeforme. Cats received selamectin topically in unit doses designed to deliver a minimum of 6mgkg(-1). Treatments were applied to the skin on each animal's back at the base of the neck in front of the scapulae. For experimentally induced infections, cats were inoculated orally with approximately 500 embryonated eggs of T. cati 56 days prior to treatment and/or approximately 150-250 larvae (L(3)) of A. tubaeforme 30 or 42 days prior to treatment. For both induced and naturally acquired infections, cats were allocated randomly to treatments (6-12 cats per treatment) on the basis of fecal egg counts to receive either selamectin or a vehicle containing the inert formulation ingredients. In all studies, adult worm counts were performed at necropsy 14 days after the last treatment administration. Against T. cati, a single application of selamectin provided a 100% reduction in the geometric mean number of adult worms for both experimentally induced and naturally acquired infections. Against A. tubaeforme, a single administration of selamectin provided a 99.4% reduction in the geometric mean number of adult worms in cats with natural infections, and an 84.7-99.7% reduction in adult worms in cats with induced infections.Two doses of selamectin administered at monthly intervals provided a 91.9% reduction in the geometric mean number of adult A. tubaeforme worms in cats with experimentally induced infections. The geometric mean numbers of adult worms (T. cati and A. tubaeforme) from selamectin-treated cats were significantly (P< or =0.0018) lower than for vehicle-treated cats in all studies. Thus, a single topical unit dosage providing a minimum dosage of 6mgkg(-1) selamectin was highly effective in the treatment of naturally acquired and experimentally induced infections of T. cati and A. tubaeforme in cats.