Abstract

The single-humped camel (Camelus dromedarius) is an important species in the arid parts of India with 0.632 million camels (17th Livestock Census, 2003, India). Some degree of parasitic burden exists in camels irrespective of the control measures adopted. Internal parasitism may endanger the health and performance of camels and may even threaten survival. Hence, parasite control is an ongoing task for camel farms.

The commonly encountered internal and external parasitic diseases having economic and pathologic significance include trypanosomiasis, hemonchosis, strongylosis, nematodiriasis, and mites. The major loss is due to trypanosomiasis followed by mange and helminthic infections. Some camels may become parasite carriers once infected. Most of the parasitic diseases escape early detection because signs are nonspecific and there is negligible mortality. Although control of parasitic disease relies on the use of anthelminthic, antiprotozoal, and anti-mange drugs, the importance of an adequate nutrition, proper hygiene, and pasture management cannot be overlooked.

Epizootiologic Findings of Parasitic Infections in Camels

Age

All age groups are susceptible to parasitic infections, but helminthic infections are more common between 1–3 years of age.¹² The ectoparasitic infections are higher in adults of >3 years of age.¹¹ The reason behind this might be that neonates are generally incapable of responding immunologically to nematode parasites. Adults usually harbor low levels of endoparasites and therefore act as a constant source of infection for more susceptible animals. Reinfection due to free grazing practices may contribute to the development of acquired resistance and low-grade infection in adults.

Sex

Sex has no influence on parasitic infections.¹¹ A higher incidence of parasites in males reported in earlier studies may have been due to males sampled being stall fed versus females sent for grazing. Low-grade infection in females may have been due to acquired resistance as mentioned above.

Breed

Four different breeds (Bikaneri, Jaisalmeri, Kachchhi, and cross breeds) found in India are considered. A higher infection rate was noticed in the Kachchhi breed.^11,12 This may reflect a breed predilection; however, further research is necessary to confirm this. For trypanosomal infections, all breeds are susceptible.⁷

Season

Winter is most conducive for harboring both ecto- and endoparasites.^5,12 The helminthic infections prevail throughout the year but are more predominant during the autumn and winter months.⁹ For hemoprotozoon infection the period immediately after rains (i.e., August to November) is most common due to the breeding of insect populations. The rugged climatic conditions in winter (September–December) are conducive to ectoparasites spread by direct contact between animals. The temperature and humidity during winter months are most congenial for mite multiplication. Conversely, the high temperature and rapid evaporation during summer are detrimental to transmission of the infective stages of the parasites.

Diagnostic Approach

The diagnosis of parasitic infections under field conditions is based on history and clinical signs. Unthriftiness, weight loss, weakness, tissue destruction, hemorrhages, anemia, reduced absorption of nutrients, and wasting are generally ascribed to internal parasitism. In trypanosomiasis, intermittent fever with disappearance of the hump, edema of the pads and abdomen, periodic convulsions, and diarrhea are noticed. In chronic trypanosomiasis, production losses in terms of milk and meat as well as infertility problems may result in huge economic loss to camel owners. Skin irritation, alopecia, and pustular and scab lesions that reduce hide quality are encountered with ectoparasitism. Anorexia may also occur.

Laboratory examination for internal parasites includes fecal examination by direct smear, sedimentation, and flotation,¹⁰ as well as eggs/g of feces (EPG) counts using a modified McMaster’s technique.¹ For hemoprotozoon infections (mainly trypanosomiasis), wet blood smear examination and stained thick blood film examinations are done.³ Since the parasitological examinations do not always detect the trypanosomes in blood, serologic tests are performed in herds. The serologic tests include the enzyme-linked immunosorbent assay (ELISA), immunofluorescence antibody test (IFAT), complement fixation test (CFT), and agglutination test. Immunoassays for detecting circulating trypanosomal antigens have been developed which can differentiate active and resolved infections.⁸ These serologic tests are specific and sensitive but not widely used under Indian conditions. The Suratex latex agglutination test may be utilized for the diagnosis of trypanosomes in the field.⁶ The polymerase chain reaction (PCR) is able to detect as few as 10 parasites, but this is costly and requires a well-equipped lab. For the ectoparasitic infections, skin scraping examination is done for identification of mites.²

Therapy

The drugs commonly used against parasitic infections in camels are listed in Tables 1 and 2.

Table 1. Anthelminthic drug dosages for camels^a

^aThe drug dose may be repeated after 3 weeks if the infection rate is heavy. In mild to moderate infections, single dose is sufficient.

Table 2. Anti-trypanosomal drug dosages for camels

Anti-Mange Drugs

Synthetic pyrethroids have been proven to be highly effective at comparatively low concentration. They are safe, economic, and have wide safety margins. Recommended drugs include fenvalerate (500 ppm) or deltamethrin (50 ppm), given three times at intervals of 7 days.⁴ Amitraz (12.5%; 500 ppm) given twice at weekly intervals is also effective in treating mange.¹³ Herbal formulations (e.g., Himax) are also available in India for treating ectoparasitic infections. The herbal formulations are eco-friendly. There is a need for further research to develop other low-cost herbal formulations for treating external parasites as well as endoparasites. Ivermectin at a dosage of 0.2 mg/kg SQ once can be used for both ecto- and endoparasites and is said to be effective.

Preventive Measures

Preventive measures include regular deworming for control of endoparasites; isolation and treatment of mange affected animals, and control of breeding of insects by maintaining proper cleanliness and hygiene. Herds should be screened for helminthic as well as external parasitic infections periodically, which can help in minimizing the losses due to parasitism. Regular grooming/brushing can help in maintaining healthy pest-free skin coats.

Regular screening of the herd for ectoparasitic, endoparasitic infections should be carried out. The following prophylactic measures are recommended for the control of parasitic infections:

1.  Deworming with broad spectrum anthelmintics such as albendazole or fenbendazole should be given at the age of 2 months when the calf starts taking grass. Deworming should be repeated every 45 days until 6 months of age then at 3-month intervals until 1 year and then at 6-month intervals.

2.  At about 4–6 months of age (i.e., before the onset of the monsoon in endemic areas) the camel calves should be given a prophylactic dose of suramin or quinapyramine pro salt (Antrycide Pro Salt; ICI or Triquin, Wockhardt; at a dosage of 0.25 ml/kg SQ) which can give protection for 3 months. Every year before the onset of the monsoon prophylaxis against trypanosomiasis should be given in endemic areas.

3.  A precautionary measure should be taken to avoid ectoparasitic infections in camels. The neonatal camel calves should not be mixed or kept in the sheds where camels with ectoparasitic infections are maintained since mange is a contagious disease which spreads rapidly. Periodically the sheds should also be sprayed with acaricides. The drug used for deworming should be rotated to avoid the development of resistance. The usage should not be excessive.

Acknowledgments

The authors are highly thankful to the facilities provided by Livestock Farming Unit of NRC on Camel, Bikaner.

Literature Cited

1.  Coles, G.C., C. Baure, F.H.M. Borgsteede, S. Gearts, T.R. Klei, M.A. Taylor, and P.J. Waller. 1992. Methods for detection of anthelminthic resistance in nematodes of veterinary importance. Vet. Parasitol. 44:35–44.

2.  Higgins, A.J. 1983. Observations on the diseases of the Arabian camel (Camelus dromedarius) and their control- a review. Vet. Bull. 53, 1089–1097.

3.  Killick-Kendrick, R., and D.G. Godfrey. 1963. Bovine trypanosomiasis in Nigeria. II. The incidence among migrating cattle with observation on the examination of wet blood preparations as method of survey. Ann. Trop. Med. Parasitol. 57:117–126.

4.  Kumar, R., G. Mal, and D. Suchitra Sena. 2005. Comparative efficacy of fenvalerate, deltamethrin, amitraz and ivermectin against sarcoptic mange in camel. Indian Vet. J. 82: 88–89.

5.  Lodha, K.R. 1977. Study on the helminth parasites in camel in Rajasthan. I.C.A.R. Scheme 1973–1977. Final report C. Vet. Anim. Sc. Bikaner.

6.  Nantulya, V.M. 1993. Suratex: a simple latex agglutination antigen test for diagnosis of Trypanosoma evansi infections (Surra). Vet. Parasitol. 49(2–4): 319–323.

7.  Pathak, K.M.L., and N.D. Kahanna. 1995. Trypanosomosis in camel (Camelus dromedarius) with particular reference to Indian subcontinent: a review. Int. J. Anim. Sci. 10:157–162.

8.  Rae, P.F., and A.G. Luckins. 1984. Detection of circulating trypanosomal antigens by enzyme immunoassay. Ann. Trop. Med. Parasitol. 78: 587–596.

9.  Raisinghani, P.M. 1992. Helminthic disease of the dromedary camel in India. Proc. 1st Int. Camel Conf. Dubai Feb. 2–6.

10.  Soulsby, E.J.L. 2005. Helminths, Arthropods, and Protozoa of Domesticated Animals. 7th ed. Elsevier India Pvt. Ltd., New Delhi. Pp. 765–773.

11.  Suchitra Sena, D., R. Kumar, and M.S. Sahani. 1999. Incidence of sarcoptic mange in camels. Indian Vet. J. 76: 556–567.

12.  Suchitra Sena, D., G. Mal, R. Kumar, and M.S. Sahani. 2000. Prevalence, haematobiochemical studies and chemotherapy of gastrointestinal nematode infection in camels. J. Vet. Parasitol. 14(2): 151–153.

13.  Suchitra Sena, D., G. Mal, R. Kumar, N.M. Singhvi, B.L. Chirania, and M.S. Sahani. 1999. Clinico-haematological and therapeutic studies on mange in camels. Ind. Vet. J. 76: 998–1000.