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Abstract
Summary
During the period, July 2007 till May 2009, a total number of 1000 camel of different ages and sex, and located in different localities were clinically examined. 390 camels out of them (39%) were infested by ticks. 224 of the camels naturally infested with tick were subjected to detailed examinations and samples collections. Based upon the degree of infestation with ticks, the infested camels (n=224) were classified into three groups. The 1st group (110 camels) showed mild infestation with ticks, the 2nd group (79 camels) showed moderate infestation and the 3rd group (35 camels) were heavily infested with ticks. Out of the examined camels infested by ticks 221 (98.88%) cases were found with single infestation with one type of tick (Hyalomma species) and only 3 (1.34%) cases were found with mixed infestation (Hyalomma species and Amblyomma species).
The clinical signs of camels infested with ticks are varies depending on the degree of infestation. Heavily infested camels with ticks showed extreme paleness of the mucous membranes, muscular weakness, depression and anorexia, the heart rate was increased (47.5±2.50/minute) than the uninfested group. Dyspnea, rapid shallow breathing and dullness were also seen. Health of 3 camels which heavily infested with ticks was severely affected and they were staggered, recumbent with subnormal temperature and died. Cases with cosmopolitan infection, ticks were close to each other on the affected areas of the skin forming a structure similar to punches of grab, particularly along lateral sides of the tail. In some infested cases, attachment of ticks causes severe irritation. The infested camel shows signs of irritability in the form of restlessness, vigorous head tossing, tail shaking and rubbing of the nose against inanimate object. On the other side, attachment and/or removal of large number of ticks causes inflammation and allergy at the infested area of the animal body. The common affected sites of ticks were under the tail, inside the ear, inside the nostrils, thighs and the udder in females and around scrotum in males. In some cases ticks also found on the hump and sides of the animal.
The hematological examination of camels infested by ticks in variable degree revealed that there is a highly significant decrease (p<0.01) in red blood cells count, hemoglobin concentration, packed cell volume with highly significant increase (p<0.01) in mean corpuscular volume. These hematological alterations are obviously noticed in heavily infested group rather than mild and moderate infested cases.
from an epizootiological point of view, the current study indicated that there is highly significant increase (p< 0.05) in the prevalence of tick infestation in camels located in El-Wady El-Gadid Governorate in comparison with others. Concerning age susceptibility of camels to tick infestation, the present work revealed that the prevalence of tick infestation was gradually increased by increasing the age of animal and the peak of infestation (44.78%) was found at 5.5 years (p<0.01). Thereafter, the prevalence of tick infestation is decreased by increasing the age of infested camel till reach 7.41% at 15 years. Camels have 18 years old or more were found tick free. Sex variance of camels and prevalence of tick infestation was also epizootiologically monitored and revealed that the susceptibility rate of females (she-camel) (44.5%) to tick infestation was highly significant (p<0.01) increase than males (37.20%). Seasonal influence on the prevalence of ticks in camels was also studied and indicated that the percentage of infestation with ticks reached its peak (p<0.01) at hot months of the year (44.3%).
Thirty-six (16.07%) of the infested camels with ticks showed premonitory signs of trypanosomosis in the form of emaciation, anaemia, debility and odema. Conclusively 20 (8.9%) of 224 camels infested with ticks were positive to Trypanosoma evansi by blood film examination. Results of PCR of blood samples for detection of DNA of Trypanosoma evansi revealed that 16 (40%) out of 40 blood samples were positive. Regarding tick examination, hemolymph smears of the tick samples taken from 83 of 224 infested camels (37.05%) were positive to trypanosoma infection and different forms of the developmental stages of Trypanosoma evansi were seen. Of these 83 positive cases, 27 (75%) of 36 camels showing clinical signs of trypanosomosis and the remained 56 positive cases were taken form 188 camels not showing obvious signs of trypanosomosis (29.79%). Results of PCR of tick samples revealed that 18 out of 40 DNA tick samples were positive to Trypanosoma evansi infection and the resulted band was at 177 bp.
15 (6.75%) out of 224 tick infested camels were carried Theileria species in their red blood corpuscles. Regarding hemolymph examination of ticks, it was noticed that 21 (9.38%) of 224 infested camels showed various developmental stages of different shapes and forms of Theileria species.
Ten (4.46%) of camels infested with ticks showed characteristic dermal lesions of contagious skin necrosis. The bacteriological examination of the collected swab samples revealed that Staphylococcus aureus was the predominant bacterial isolate. Regarding ticks, Staphylococcus aureus was isolated from ticks collected form 12 tick infested camels. The negatively cultured ticks were tested by polymerase chain reaction for detection of DNA of Staphylococcus aureus which revealed positive band at 270 bp in 7 (16.28%) out of 43 tick DNA samples.
Nineteen (8.48%) of 224 tick infested camels showed abscesses in the superficial cervical lymph nodes either unilateral or bilateral, and bacteriological examination indicated that Corynebacterium pseudotuberculosis was the prominent pathogen isolate from the affected lymph nodes. The bacteriological examination of ticks collected from clinically diseased camels with pseudotuberculosis revealed that Corynebacterium pseudotuberculosis could be isolated form ticks collected from 19 camels showed lymph node abscesses and 9 camels with no abscesses.
Fourteen (6.25%) of 224 tick infested camels showed sings of respiratory distress in the form of nasal discharge, cough and extension of head and neck. These cases were examined by blood film and revealed the presence of intercellular bipolar microorganisms in-between red blood cells in 42.86% of 14 cases. The bacteriological examination of the collected nasal swabs form the affected camels was also culturally positive to Pasteurella multocida.
Sex hundred and thirty bacterial strains could be recovered form ticks examined bacteriologically. These isolated bacteria including 424 Gram-positive bacteria (67.30%) and 206 Gram-negative bacteria (32.70%).
The microscopical examination of gut smears of the collected ticks stained by Geimenz stain elucidated that the presence of the characteristic morphological feature of small red cocco-bacilli of Rickettsia species in 0.41% of the examined ticks. Meanwhile, the microscopical examination of the yolk sac membrane of the emberyonated chicken eggs inoculated with tick’s organs suspension and results of PCR examination detection of Rickettsia species were negative.