Infected Camels Research Articles

An outbreak of abortions and high neonatal mortality associated with Trypanosoma evansi infection in dromedary camels in the Canary Islands

Trypanosoma evansi was diagnosed for the first time in the Canary Islands (Spain) in 1998 in a dromedary camel. Seroprevalences of 4.8% up to 9% have been observed using different diagnostic methods. Affected animals have been treated but the dissemination of the disease is unknown. This article presents an outbreak of abortions and high neonatal mortality attributable to T. evansi infection in camels as well as the clinical assessment of the affected animals. The patients were diagnosed by routine checking (three pregnant animals), after abortion (five dams), or after delivered premature or weak calves (eight dams). At clinical examination, 2 out of 16 affected animals showed moderate signs of chronic form, particularly hyporexia and intolerance to exercise. The aborted fetuses were aged 6–8 months of gestation, approximately. The main laboratorial findings were regenerative anemia (haemolytic anemia), lymphocytic and monocytic leukocytosis, hyperproteinemia, hyperglobulinemia, hypoglycaemia, serum urea increased and serum iron decreased. Treatment using trypanocidal drug (Cymelarsan ®) resulted highly effective. Massive treatment would be recommended in the entire camel population in the Canary Islands (less than 2000 animals), as therapeutic or preventive measure, in order to control and to achieve an eventual eradication of the disease.

A comparative evaluation of parasitological, serological and DNA amplification methods for diagnosis of natural Trypanosoma evansi infection in camels

A representative number of 217 camels ( Camelus dromedarius) from different areas of western Rajasthan State, India, were examined from July 2002 to May 2003 for Trypanosoma evansi infection. The tests used were parasitological (wet blood film, WBF; stained thin blood smear, TBS), immunodiagnostic (double antibody sandwich enzyme linked immunosorbent assay for antigen detection, Ag-ELISA), and DNA amplification by polymerase chain reaction (PCR). These techniques were compared and the best efficiency was found for the last named (PCR). A prevalence of T. evansi infection was detected in 17.05, 9.67, 4.60 and 4.14% by PCR, Ag-ELISA, TBS and WBF with a sensitivity of 100, 56.75, 27.02 and 24.32%, respectively. PCR revealed a specific 227 bp band in positive samples. The intensity of PCR bands was variable in different test samples depending upon the level of infection in the test samples. The history of intermittent fever, emaciation, oedema, poor body condition significantly correlated with positive serological status in ELISA as well as trypanosome DNA detection by PCR.

Trypanosoma evansi sialidase: surface localization, properties and hydrolysis of ghost red blood cells and brain cells-implications in trypanosomiasis.

A membrane-bound sialidase was isolated from blood stream (BS) Trypanosoma evansi partially purified and characterized. The enzyme is a glycosyl phosphatidyl inositol (GPI) membrane anchored protein. It was solubilized from T. evansi cells recovered from infected camel blood by detergent treatment with Triton CF 54 and partially purified by a series of chromatography steps. The enzyme was optimally active at pH 5.5 and 37 degrees C. It had a KM and Vmax values of 4.8 x 10(-6) M and 3.75 x 10(-6) mol/min x mg protein with Neu5Acalpha2, 3lac as substrate respectively. The KM and Vmax values with fetuin (4-nitrophenyl-oxamic acid) as substrate were 2.9 x 10(-2) M and 4.2 x 10(-3) mol/min x mg protein in the same respect. Kinetic analysis with methly umbelliferyl sialate (MU-Neu5Ac) gave KM and Vmax values of 0.17 mM and 0.84 mmol/min x mg protein respectively. The T. evansi SD could hydrolyse internally linked sialic acid residues of the ganglioside GM2, but was inactive towards colomic acid, and NeuSAc2, 6. lac. When ghost red blood cell (RBC) was used as substrate, it desialylated the RBC in the following order of efficiency; mouse, rat, camel, goat, and dog. Similarly, cerebral cells isolated from BalbC mouse was desialylated by the T. evansi SD. Inhibition studies using 2-deoxy-2, 3 didehydro-N-acetyl neuraminic acid (NeuAc2, 3en) against MU-Neu5Ac revealed a competitive inhibition pattern with Ki of 5.8 microM. The enzyme was also inhibited non-competitively by parahydroxy oxamic acid (pHOA), and competitively by N-ethylmaleimide and N-bromosuccinate with Ki values of 25, 42, and 53 microM, respectively. It was activated by Mg2+ ion and inhibited by Cu2+ and Zn2+.

Evaluation of antigen and antibody rapid detection tests for Trypanosoma evansi infection in camels in Kenya

The card agglutination test for Trypanosoma evansi (CATT/ T. evansi) for the detection of antibodies, and Suratex ® for the detection of circulating antigens were compared in a cross-sectional study involving camels in eastern and central parts of Kenya. Of the 2227 camels screened, 2038 were owned by nomadic pastoralists in T. evansi endemic areas in eastern Kenya. A herd of 86 camels were from a ranch in Mugwoni. In Athi River area, 35 camels belonged to Kenya Trypanosomiasis Research Institute, and 68 were slaughter animals. Diagnostic sensitivity estimates were obtained by testing sera from 51 camels that had been found to be parasitologically positive by the haematocrit centrifugation technique, buffy-coat technique and mouse inoculation. Diagnostic specificity was estimated by testing sera from 35 camels known to be trypanosome-free. Positive and negative predictive values (NPVs) were calculated using a range of prevalence values. The sensitivity of CATT/ T. evansi (68.6%) was higher than that of Suratex ® (58.8%), but not significantly. Both tests had equally high specificity (100%). The overall prevalence was 2.3% (51 out of 2227) by parasite detection, 32.2% (327 out of 1017) by CATT/ T. evansi and 19.6% (188 out of 961) by Suratex ®. Overall, there was a positive association between CATT/ T. evansi and Suratex ® though the strength of association was low (McNemar’s test=46.12, P=0.001; kappa=0.26, CI: 0.20–0.33). Parasite prevalence ranged from 0% in several herds to 27.8% in a herd in Isiolo. Prevalence was highest in Isiolo with 2.5% (51 out of 2030) by parasitological detection, 38.8% (321 out of 828) by CATT/ T. evansi and 21.9% (169 out of 772) by Suratex ®. In Mugwoni prevalence was 7 and 18% by CATT/ T. evansi and Suratex ®, respectively, and no parasites were detected. In Athi River Suratex ® detected 2.9% (3 out of 103) positive while CATT/ T. evansi and parasitological methods gave negative results. At prevalence values between 10 and 100%, CATT/ T. evansi as well as Suratex ® had infinitely high positive predictive values, whereas Suratex ® had a lower NPV than CATT/ T. evansi. In conclusion, results of this study showed that CATT/ T. evansi and Suratex ® were able to detect aparasitaemic infections rapidly and were more sensitive than parasitological methods in revealing the true extent of trypanosomosis in a herd. The tests effectively complemented parasitological methods in the detection of T. evansi infections in camels.

Ascorbic acid content of blood plasma, erythrocytes, leukocytes and liver in camels (Camelus dromedarius) without or with parasite infections.

Healthy camels (Camelus dromedaris) and those naturally infected with trypanosomiasis, sarcoptic mange, and helminthiasis were compared as to ascorbic acid (vitamin C) contents of red blood cells, white blood cells, whole blood, plasma, and liver. The camels were kept under natural grazing conditions in Sudan. Reduced levels of vitamin C were found in camels with parasite infections, especially in animals with trypanosomiasis. It is suggested that the low vitamin C status in infected camels is caused by increased utilization and/or decreased synthesis of vitamin C.

Serodiagnosis of cystic echinococcosis in naturally infected camels.

An ELISA was developed for serological detection of Echinococcus granulosus infection in dromedary camels. Antigen B (AgB) partially purified from hydatid cyst fluid of camels or sheep naturally infected with cystic echinococcosis (CE) due to E. granulosus, as well as a recombinant antigen B product (r-AgB) were used in an ELISA to screen panels of serum samples from slaughtered camels naturally infected with CE. Native hydatid cyst fluid antigen preparations were able to detect antibodies in sera from a significant proportion of camels with CE, as confirmed at post-mortem. Seroreactivity however, was variable. ELISA specificity for sera from naturally infected camels versus inspection-negative animals ranged from 90 to 99%. Native antigen B gave the highest sensitivity (97%) in ELISA for camel CE confirmed at slaughter. In contrast, r-AgB gave lower sensitivity for camel (84%) and sheep (28%) CE. The r-AgB-ELISA was, however, highly specific (90 and 95%) respectively for both camel and sheep natural CE infection. These results indicate that an ELISA based on serum antibody detection to AgB could be developed for immunodiagnosis of cystic echinococcosis in camels.

Detection of Brucella Species in the Milk of Infected Cattle, Sheep, Goats and Camels by PCR

One hundred and three milk samples were collected from 52 cows, 21 ewes, 18 goats and 12 camels. The animals tested positive to at least one of the following: (1) standard tube agglutination test (SAT); (2) Rose Bengal plate test (RBPT); (3) milk ring test (MRT). All milk samples were examined by culture and single-step polymerase chain reaction (PCR) techniques for detection of Brucella species. The PCR assay amplified Brucella -DNA from 29 bovine milk samples, 10 from sheep, 13 from goats and one from a camel. The direct culture method detected Brucella organisms from 24 samples of cows' milk, 12 from sheep, 10 from goats and failed to detect any Brucella organisms from camels' milk. PCR detected up to 100 colony forming units (CFU) of B. abortus per millilitre of milk in 100% of diluted milk samples, and 1000 CFU of B. melitensis from 70% of milk samples. Although the overall sensitivity of the PCR was higher than the culture method, it should be possible to increase the sensitivity to detect lower numbers of Brucella organisms in field samples. The speed and sensitivity of the PCR assay suggest that this technique could be useful for detection ofBrucella organisms in bovine milk, as well as in sheep, goat, and camels milk.

Prevalence of antibodies to Brucella spp. in cattle, sheep, goats, horses and camels in the State of Eritrea; influence of husbandry systems

Samples from 2427 cattle, 661 goats, 104 sheep, 98 camels and 82 horses were screened for brucella infections by the Rose Bengal Test and positive reactors confirmed by the complement fixation test. In cattle, the highest individual seroprevalence was in dairy herds kept under the intensive husbandry system, with an individual prevalence of 8.2% and unit (herd) seroprevalence of 35.9%. This was followed by the pastoral husbandry system in the Western Lowlands with 5.0% individual but a higher unit (vaccination site) prevalence of 46.1%. The lowest was in the mixed crop-livestock system in the Southern Highlands with individual 0.3% and unit (village) prevalence of 2.4%. In sheep and goats, no positive animals were detected in the mixed crop-livestock areas. In the Eastern Lowlands individual prevalences of 3.8% (goats) and 1.4% (sheep) and unit prevalence of 33.3% (goats) and 16.7% were found, while 14.3% of individual goats and 56.3% of the units in the Western Lowlands were positive. No positive horses were found. The present study documents the first serological evidence of Brucella spp. infection in camels (3.1%) in Eritrea.

Brucellosis in Saudi Arabia: Past, Present and Future

Brucellosis in Saudi Arabia: Past, Present and Future

Prevalence of Surra among camels and horses in Jordan

The prevalence of Trypanosoma evansi infection among camels and horses in Jordan was studied using thick blood smears and inoculation techniques with mice and rats. A total of 437 camels and 83 horses from four climatic zones were surveyed. In addition, 40 donkeys, 32 cattle and 35 goats in contact with infected camels and horses were also tested in the same way. Clinical disease was evident in 8.2% of the camels (36 out of 437) and in 9.6% of the horses (8 out of 83). Infection was limited only to the Sweama area on the Dead Sea (within the warm desert-climatic zone), with prevalence of 30.5% and 33.3%, respectively, for camels and horses. Donkeys, cattle and goats examined were all free from T. evansi. Clinically affected camels were positive by both, thick blood smear and mouse and rat inoculations. Rat and mouse inoculations revealed ( X 2=3.2, df=1, exact p=0.07) greater number of positive cases in horses than those revealed by thick blood smears. T. evansi-infected camels and horses showed all the clinical signs known for Surra. In addition, it was observed that 100% of infected camels stared at the sun.

Outbreaks of dermatophilus congolensis infection in camels (Camelus dromedarius) from the Butana region in Eastern Sudan

Natural Dermatophilus congolensis infection of camels has been reported in Kenya in semi-arid areas. Research is being conducted to discover how widespread the condition is in neighbouring countries with similar eco-climatic conditions. Severe skin infections of camels from the Butana region of Eastern Sudan were examined. The infections were first found in two herds of adult camels, of which 50%-75% of the animals were affected. In the other thirteen herds examined, camel calves were more likely to be infected (34%) than adults (8.9%), and lesions were more severe and involved most parts of the body. The lesions began as hair matting and later developed into hard crusts. The case fatality rate ranged from 10% to 30%. D. congolensis was isolated from the scabs. Camel dermatophilosis was found to be among the most serious problems faced by camel herders in the Butana region.

Diagnosis of Trypanosomiasis in Experimental Mice and Field-Infected Camels by Detection of Antibody to Trypanosome Tyrosine Aminotransferase

Sera from animals with acute and chronic Trypansoma evansi infections were examined directly for trypanosome tyrosine aminotransferase activity and indirectly for their ability to inhibit tyrosine aminotransferase activity. It was shown that sera from acutely infected mice and camels with high parasitemias contained significant levels of trypanosome tyrosine aminotransferase activity. In contrast, the sera from chronically infected mice and camels did not contain significant tyrosine aminotransferase activity, but they were able to neutralize the enzyme activity in trypanosome homogenates. The sera from camels with other pathological conditions did not neutralize this enzyme activity. It is suggested that the inhibitory factor in the chronic sera is antibody. The potential use of the direct enzyme assay and the indirect neutralization assay as diagnostic tools are discussed. Finally, the use of these assays to distinguish between early (acute) and late (chronic) infections are also suggested.

Comparative studies on the sensitivity of polymerase chain reaction and microscopic examination for the detection of Trypanosoma evansi in experimentally infected mice

Trypanosoma evansi, a protozoan parasite in the blood of camels is routinely diagnosed by finding the flagellates in the wet films or stained smear of peripheral blood, examined under a microscope. Although specific, this method is not sensitive at early stages of infection. We have tested the use of polymerase chain reaction (PCR) in the identification of T. evansi in different stages of infection in mice and compared its sensitivity with that of the standard microscopic examination method. Using a specific pair of primers, it was possible to identify T. evansi in the blood of infected mice. Experimentally, groups of mice were infected with T. evansi, isolated from a naturally infected local camel and blood samples were collected every day for 30 days post-infection. Direct microscopy or PCR was applied to detect parasitaemia. Results showed that during the acute phase of infection, parasites were detected by PCR three days earlier than by microscopy. Furthermore, the infected mice were consistently positive by PCR during the chronic phase while the parasites could not be demonstrated during this period using microscopic examination. These findings suggest that PCR may be applied to camel trypanosomosis during both acute and chronic phase of infection. Furthermore, it would provide an excellent tool in the evaluation of treatment of anti-trypanocidal drugs.

Prevalence of cystic echinococcosis in camels (Camelus dromedarius) in Libya.

In an abattoir study, 514 camels, slaughtered for meat production in different areas of northern Libya were examined for the presence of cystic echinococcosis (CE). In addition, 367 sheep and 184 goats were examined. The overall prevalence of infection with CE was 48% in camels, 15.8% in sheep and 3.8% in goats. The infection rate, number and size of cysts were significantly higher in older camels. In six city abattoirs across northern Libya, i.e. Zawia, Tripoli, El-Khumes, Mesurata, Sirt and Benghazi, the prevalence rate of infection in camels ranged from 38.7% to 55.2%, in comparison with sheep and goat rates which were between 0% and 37.9% and 0% and 8.2%, respectively. In camels, the lungs were the most frequently infected organs (85.4%) with liver cysts occurring at a significantly lower rate (33%). In contrast, the liver was the predominant infected site with prevalence values of 86% and 100% in sheep and goats, respectively. More than 90% of camel hydatid cysts were fertile. The possible role of camels in the transmission of CE in Libya is discussed.

Diagnosis of Trypanosoma evansi in Saudi Arabian camels (Camelus dromedarius) by the passive haemagglutination test and Ag-ELISA.

The passive haemagglutination test and Ag-ELISA were employed to monitor antibody titres and antigenaemia levels in 4 Najdi camels experimentally infected with Trypanosoma evansi. The two tests were also used to determine the prevalence of trypanosomiasis in a total of 218 Najdi camels in the Gassim region, Central Saudi Arabia, during the period from October 1992 to September 1993. Trypanosoma evansi antibodies in the experimentally infected camels rose after 14-21 days and reached a maximum of between 1:64 and 1:128 by the 12th week post infection. Circulating antigens were detected in the experimentally infected camels one week post infection and antigenaemia levels fluctuated but generally remained above preinfection OD values. The results obtained from the field survey showed that 5.5% of the sampled camels were parasitologically positive for trypanosomes, while 19.7% were serologically positive by the passive haemagglutination test and 13.8% by Ag-ELISA. No significant age difference in seropositivity was observed in the tested camels.

Evaluation of various diagnostic techniques for Trypanosoma evansi infections in naturally infected camels

One hundred and eight camels ( Camelus dromedarius) from Trypanosoma evansi endemic areas of the Thar Desert of Rajasthan State, India, were evaluated by various diagnostic tests including parasitological tests (wet blood film — WBF, stained thick blood film), chemical test (mercuric chloride), biological test (mouse subinoculation — MSI), and immunodiagnostic tests based on antibody detection (double immunodiffusion test — DID, card agglutination test — CATT), antigen detection (double antibody sandwich enzyme linked immunosorbent assay — Ag-ELISA). Of the tested camels 49 were found infected using the WBF of which nine gave false negative results with the mercuric chloride test. The efficacy of MSI was 87.03 percent, while the mercuric chloride test was 60.18 percent efficient. The diagnostic efficacy of CATT (72.22 percent) was found to be much better than DID (28.70 percent). Ag-ELISA was 86.11 percent efficient in detecting trypanosomal antigens. A good correlation was found between the positive results obtained by wet blood film, CATT and Ag-ELISA. It was inferred that CATT can be used to study the seroprevalenee of T. evansi with great ease, however, trypanosome antigen detection may give a more accurate idea of the prevalence of T. evansi in an endemic area.

Serology of Orthopoxvirus cameli infection in dromedary camels: Analysis by ELISA and Western blotting

An enzyme-linked immunosorbent assay (ELISA) was developed, together with a Western blotting technique, for the detection of total and IgG and IgM antibodies to camelpox virus ( Orthopoxvirus cameli) in camel ( Camelus dromedarius) sera and for identifying the seroreactive antigens of the virus. A total of 520 camels from different regions in Libya were tested. The overall seropositivity rate in the examined herds was 9.8%, and varied between herds from 0 to 30%. Two viral antigenic determinants (31 and 35 kDa) were shared by the Western blotting patterns of all the positive camel sera tested. The developed ELISA assay showed ability to differentiate between orthopox and parapoxvirus infections in camels. It is considered that the ELISA technique is justified for serodiagnosis of camelpox in the camel and could be easily modified and usefully applied to other species at risk of poxvirus infection.

Use of suratex for field diagnosis of patent and non-patent Trypanosoma evansi infections in camels

Use of suratex for field diagnosis of patent and non-patent Trypanosoma evansi infections in camels

The haematological and biochemical effects of the gastrointestinal nematodes prevalent in camels (Camelus dromedarius) in central Saudi Arabia.

Coprological examinations on 1200 Najdi camels (Camelus dromedartus) in the Gassim region of central Saudi Arabia between October 1992 and September 1993 revealed the presence of strongyle-type, Nematodirus and Strongyloides eggs. In addition, examination of the gastrointestinal tracts of 240 camels slaughtered in different abattoirs in the Gassim region from March to August 1994 revealed 11 species of helminths. Infection with gastrointestinal trichostronglyes resulted in normocytic, normochromic anaemia. Adult infected camels showed leukocytosis, a decrease in total serum protein concentration and increases in blood urea concentration and in serum creatine phosphokinase activity.

Evaluation of the silicone centrifugation technique in the detection of Trypanosoma evansi infection in camels and experimental animals.

Evaluation of the silicone centrifugation technique in the detection of Trypanosoma evansi infection in camels and experimental animals.