Bacterial diseases: Tetanus, Anthrax, botulism, Johne’s disease (Mycobacterium avium paratuberculosis infection) although camels are more severely affected than other ruminants.
Mastitis: Three main procedures have been used by different
researchers for the diagnosis of mastitis in camels.
California Mastitis Test (CMT) and milk somatic cell
count (SCC) have been used. The most commonly isolated organ-
isms were Micrococcus sp., Streptococcus agalactiae,
Staphylococcus aureus, followed by Arcanobacterium
sp. and E. coli.
**Diagnosis of mastitis: **Three main procedures have been used by different
researchers for the diagnosis of mastitis in camels. California Mastitis Test (CMT) and milk somatic cell count (SCC) have been used, often simultaneously by several investigators, and found to correlate well for the detection of clinical mastitis [78, 80, 83, 84]. CMT showed 77% sensitivity and 91% specificity for the diagnosis of camel mastitis in one study.
In an effort to provide a quick diagnostic
test for subclinical mastitis in camels, Abdurahman
[86] and Guliye et al. [79] tried the detection of N-
acetyl-beta-glucosaminidase (NAGase) and serum
albumin in milk, but the results were not encour-
aging. Serum albumin content of milk was not
correlated with udder infection, while great varia-
tions were recorded in the NAGase values in both
infected and healthy udders.
Trypnosomiasis in camels:
This group of diseases caused by protozoa of the genus Trypanosoma affects all domesticated animals. The major veterinary species are T congolense, T vivax, T brucei brucei, and T simiae. T brucei rhodesiense and T brucei gambiense are zoonotic, with people as the predominant host.
Trypanosomosis in camels is a protozoal disease caused by Trypanosoma evansi (T. evansi) which is transmitted by hematophagous flies including Tabanus and Stomoxys.
Most people generally associate trypanosomiasis with tsetse flies (Glossina spp.) and tropical Africa. Camel trypanosomiasis proves an exception. Most camels live outside of Africa’s tsetse belt, and their trypanosomiasis is caused by Trypanosoma (Trypanozoon) brucei evansi (hereafter referred to as Trypanosoma evansi), which is transmitted mechanically and is not dependent on the presence of tsetse flies. This trypanosome species causes the most widespread and the most important disease in camels.
However biting flies and insects are the major reason for the spread of evansi to the other regions. spread.
Camels are also affected to a lesser extent by tsetse-transmitted trypanosome species, T. (T.) brucei brucei (10, 22, 23, 36, 37) and T. (Nannomanas) congolense (4, 10, 23). The latter trypanosome species causes acute disease with very high mortality.
Trypanosoma evansi is transmitted mechanically by haematophagous biting flies. No developmental stage in a vector has been demonstrated which differentiates the parasite from brucei. Tabanids (horseflies) play the major role in transmission, while Stomoxys spp. and Lyperosia spp. may also transmit it. An interrupted feed upon an infected host leaves the fly hungry. Whenever it moves to another host, it can establish a new infection through its trypanosome-contaminated mouthparts. Trypanosomes remain infective on the proboscis for a short period only. The parasite replicates in camels, horses, donkeys, dogs, cattle, water buffaloes and even elephants. Equines and dogs are very susceptible and usually die after an acute course of the disease. Dogs may also become infected by eating meat from a trypanosome-infected carcass (23). Cattle, sheep, goats and antelopes often carry the parasite subclinically, acting as asymptomatic reservoirs.
Parasite morphology and biology
Trypanosoma evansi is morphologically identical with, and indistinguishable from, slender forms of other members of the subgenus Trypanozoon. Akinetoplastic populations are relatively common, particularly after drug exposure (18, 32). It can be distinguished from brucei by isoenzyme electrophoresis (8). T. evansi is not restricted to the blood stream. Like other members of the subgenus Trypanozoon, it enters tissue compartments or other body fluids; it may cross the blood-brain barrier (23) or enter the joint fluids (Röttcher and Schillinger, unpublished results), thus being less accessible to chemotherapy. This situation is comparable to chronic brucei infections in mice (16) or to the late stage of human sleeping sickness.
Symptoms and the course of the disease
Surra can attack camels at any age, even foetuses. There is a particularly high incidence of infection in juvenile camels shortly after weaning. Numerous environmental and host factors influence the course of the disease, such as other infections, nutritional status, age, pregnancy, previous exposure or immunosuppression by other diseases, and stress. In a typical case, the dromedary loses weight, develops a drooping hump, is unable to walk long distances, and may or may not develop oedema of the feet, brisket, 465 underbelly and eyelids; the coat becomes rough. In the initial attack of fever there may be lacrimation, shivering, reduced appetite and mild diarrhoea. The animal always shows progressive anaemia and fluctuating body temperature with initial peaks of fever up to 41 °C. Later, the appetite is relatively unimpaired and the temperature may become normal or slightly elevated. The mucous membranes are pale and the packed cell volume (PCV) drops to below 25% (v/v), sometimes as low as 10% (v/v). The herders may notice a characteristic odour of the camel’s urine and identify infected animals by this sign alone (23). The odour of the urine may be due to ketone bodies, which were found to be elevated in trypanosome-infected camels (Schillinger, unpublished results). Abortion in all stages of pregnancy is common (20, 23). If the foetus happens to be full term it may be born alive but weak with parasitaemia (34). Death of the newborn calf ensues within two weeks. Lactating females produce less milk, and cases of blindness and central nervous lesions have been reported to be sequelae of trypanosomiasis. The herd eventually reaches an endemic disease situation. Some animals may carry trypanosomes for years whereas others never do. Within such a group there are all forms and stages of surra from new infections to subclinical and chronic conditions. The course of the disease varies widely. In Kenya, a small percentage of animals die within 2 to 5 months of contracting the disease. Some live for up to four years with subclinical infections and some eventually self-cure. The overall productivity of a camel herd regarding calves, milk and weight gains is greatly impaired. A lethal outcome is relatively rare, but mortality may reach 20%.
Although trypanosomosis of camels occurs in both acute and chronic forms, it commonly occurs in the chronic form. Chronically infected camels show an intermittent fever, pale mucous membranes, corneal opacity, emaciation, thigh muscle atrophy, abortion and the loss of production[1]. Camel trypanosomiasis, also known as surra, is a disease causing morbidity up to 30.0% and mortality of around 3.0%[l2].
Diagnosis:
The herder may report weight loss, weakness, blindness, abortions or changes in the odour of the urine. For the veterinarian, the leading sign is anaemia, the mucous membranes being pale or white. Tachycardia results. There may or may not be pyrexia, lacrimation, cachexia, enlarged lymph nodes, reduced appetite and oedemas, the latter appearing first on the underbelly.
Post-mortem examination reveals no absolutely typical signs, but some degree of anaemia is often visible. Skeleton and heart muscles are pale, and there are signs of dehydration, pericardial effusion, enlarged lymph nodes and splenomegaly.
For mass screening of dromedary herds there are numerous indirect tests. The formol-gel test (19) and the mercuric chloride test (3) detect only high serum globulin levels, which are a common feature in camel trypanosomiasis, but both are nonspecific.
For mass screening of dromedary herds there are numerous indirect tests. The formol-gel test (19) and the mercuric chloride test (3) detect only high serum globulin levels, which are a common feature in camel trypanosomiasis, but both are nonspecific. Specific serological tests have been widely applied: the capillary agglutination test of Jatkar et al. (15), the passive haemagglutination test of Jatkar and Singh (14), the immunofluorescent antibody test and the enzyme-linked immunosorbent assay (ELISA) of Luckins et al. (24). Recently, Zweygarth et al. (41) described a simplified ELISA for camel trypanosomiasis using a commercially available protein A-peroxidase conjugate. The serodiagnosis of camel trypanosomiasis with these tests requires a somewhat sophisticated laboratory. Recently, however, a card agglutination test set has been introduced for the diagnosis of Gambian sleeping sickness (“Testryp CATT” , Smith & Kline). This card test has been successfully adapted for the serodiagnosis of evansi infection in camels (40).
PM Lesions
Post-mortem examination reveals no absolutely typical signs, but some degree of anaemia is often visible. Skeleton and heart muscles are pale, and there are signs of dehydration, pericardial effusion, enlarged lymph nodes and splenomegaly.
Lab Findings:
Comparison of hematologyical and serum biochemical profiles between the camel infected by T. evansi and uninfected camels indicated anemia, leukocytosis, hyperproteinemia, hypoalbuminemia, hyperglobulinemia, reduction A/G ratio, increased α2, β and globulins and decreased of α2 globulins and increased the concentration of gamma-glutamyl transferase enzyme.
Treatment
Two drugs are recommended for the treatment of evansi infections in dromedaries: suramin and quinapyramine, as sulphate or prosalt
The recommended dosage is 12 mg/kg or about 5 g per adult camel, given by slow intravenous injection. Paravenous application can result in phlebitis. The drug is excreted slowly, which results in some prophylactic drug cover for 6-12 weeks depending on the dosage and the infection challenge. Suramin is well tolerated at up to three times the recommended dose. There are now numerous suramin-resistant strains of T. evansi.
Quinapyramine is simpler to dissolve than suramin and its subcutaneous application is easier. Quinapyramine methylsulphate is used as a curative drug, whereas a mixture of two salts, quinapyramine methylsulphate and quinapyramine chloride at a ratio of 3:2, is applied for prophylactic purposes (Pro-Salt RF). Prophylactic cover lasts for about 4 to 6 months.
In camels, 0.5 mg/k g of isometamidium given intravenously as a 2 % solution is well tolerated (1, 2). This route of application is curative in acute cases but fails when parasites have already entered extravascular sites.
Melarsoprol is curative, but has considerable disadvantages because it causes severe local reactions, unless given strictly intravenously. It has a narrow therapeutic index and treatment depends on accurate body weight and dosage determination. A dosage of 3.6 mg/k g is tolerated but should not be exceeded
** The filarial nematode Onchocerca fasciata** lives as an adult worm, forming well developed fibrous tissue nodules within the fascial sheath of various parts of the camel body. multiple nodules with 1 to 2.5 centimeters in diameter were observed. The nodules were dry and raised, tactile or hard in their texture.
The filarial nematodes Onchocerca spp. usually inhabit subcutaneous tissue, ligaments and aponeuroses of large mammals.
** Histopathologically**, multifocal granulomatous inflammatory reactions were observed to be associated with the parasites in the affected areas. Transverse and longitudinal cross sections or fragment of the worms with different degrees of surrounding inflammatory reaction were scattered inside the granulomas.
Tissue samples for histopathological studies were fixed in 10% neutral buffered formalin, dehydrated in graded ethanol, cleared in xylene, embedded in paraffin wax and sections of 5 µm in thicknesses were stained by haematoxylin and eosin.
degenerated or calcified cysts were surrounded by parasitic granulomas containing giant cells, eosinophils, macrophages, lymphocytes and fibroblasts were also compatible with previous findings
On cross section, tangled masses of thin filarial worms were surrounded by a thick whitish fibrous connective tissue. The adult worms obtained from nodules were identified as O. fasciata based on cuticle structure
DDx
There is a group of diseases characterized by inflammatory nodules which generally located on the lower leg. They have certain clinical appearances in common, which often makes a differential diagnosis difficult or impossible on clinical grounds alone.
Currently, four filarial species are known to affect dromedary camels, namely, Onchocerca fasciata Railliet and Henry, 1910 and Deraiophoronema evansi (Lewis, 1882) (syn: Deraiophoronema cameli Romanovitch, 1916; Dipetalonema evansi), which are specific to camels
sometimes mistaken as tuberculosis infection of lymph nodes.
Allergic reactions to the bites of small flies may produce similar lesions or exacerbate microfilaria-associated dermatitis.
ERYTHEMA INDURATUM OF BAZIN (EIB) Etiological relationship with tuberculosis (TB)
TST- Tuberculin Skin Test to rule out TB -Intradermal tuberculin test at the axilla of a dromedary
the single intradermal comparative tuberculin test is used and the site of inoculation is the axilla (5). The axillary site was found to be superior to cervical and tail-fold sites in studies using small numbers of llamas and dromedaries (15, 44). For statutory testing, purified protein derivatives of bovine and avian tuberculin (each 0.1 ml) are injected into a shaved area of the axilla, and the thickness of the skin is measured immediately before and 72 h after the injections (Fig. 7). A positive result is indicated by an increase in skin thickness at the bovine site that is greater than the increase at the avian site.
Rx
Following Endectocides are used
Moxidectin (400 mcg/Kg)is a potent, broad-spectrum endectocide (antiparasitic that is active against endo- and ecto-parasites) with activity against nematodes, insects, and acari.
Ivermectin (200 mcg/Kg)
As for microfilaricidal dosages of ivermectin, pretreatment with Benadryl® (2 mg/kg IM) and dexamethasone (0.25 mg/kg IV), prior to milbemycin (0.5 mg/Kg) treatment, may prevent adverse reactions, particularly in dogs with high microfilarial counts.
Milbemycin Oxime Antiparasitic drug. Avermectins (ivermectin-like drugs) and milbemycins(milbemycin and moxidectin) are macrocyclic lactones and share similarities, including mechanism of action. These drugs are neurotoxic to parasites by potentiating glutamate-gated chloride ion channels in parasites.
Doxycycline - Twice daily 5 g per 200 kg body weight for 3 - 5 days.
Doxycycline may be used in animals with decreased kidney function because it is eliminated primarily via the GI tract.
Tetracycline antibiotics should be avoided during pregnancy because of risk of skeletal limb abnormalities and discoloration of teeth. Doxycycline may pose less risk than other tetracycline antibiotics; although, its use should be avoided unless the benefits outweigh the potential risks