Morphological and molecular characterization of Amblyomma variegatum (Acari: Ixodidae) ticks from Nigeria

The association of most tick-borne pathogens with specific tick species has made it imperative that proper identification and characterization of such tick vectors is necessary for the purpose of developing effective tick and tick-borne control strategies. This study was undertaken to identify and characterize Amblyomma species ticks collected from cattle in Plateau State, North-Central, Nigeria. They were morphologically identified using diagnostic characters. Further confirmation and characterization was done genetically using a 460bp-long partial fragment of the 16S rRNA gene amplified by polymerase chain reaction (PCR). The amplified fragment was cloned and sequenced for the phylogenetic dendogram. All the examined ticks were identified as A. variegatum which was confirmed by 16S rRNA gene sequences analysis, and phylogenetic inferences showed a 99% similarity and grouping to A. variegatum of African origin. However, the A. variegatum sequences from Nigeria were clustered into 2 groups, but formed a distinct clade from the A. variegatum sequence from Ethiopia. This study was able to conclusively identify and characterize A. variegatum ticks from the study areas by utilizing morphology and molecular genotyping based on sequencing of the 16S rRNA gene.Keywords: Amblyomma variegatum, Morphology, 16S rRNA, PCR, Sequencin

Pneumonia as the cause of death in gilts experimentally infected with Trypanosoma brucei

application/pdfA study was conducted in 24 gilts to determine the effect of Trypanosoma brucei infection on their reproductive efficiency. The infected gilts developed clinical trypanosomosis following a prepatent period of 2-3 days with 1.8 x 10⁶ trypanosomes per gilt. The clinical signs were observed intermittent fever, pale mucus membranes, short moist cough, moist rales, mucopurulent ocular discharges and hyperemia of the skin, reduced feed intake, and loss of body condition, recumbency, uncoordinated movements, posterior paresis and death of gilts. The cause of death in the pigs was pneumonia caused by Escherichia coli. Grossly, the lungs were severely congested and had undergone gray hepatization. Histopathologically, the lungs had thickened and congested alveolar walls, and were infiltrated by mononuclear cells which were noticed more in the lung parenchyma. The role of secondary bacterial infection in the pneumonia observed, orchestrated by immunosuppression, which is a classical attribute of trypanosome infection is discussed.journal articl

Abortion and its probable cause in gilts experimentally infected with Trypanosoma brucei

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Ultrastructure of secretory cells in the gut of the cattle-tick Boophilus microplus

The ultrastructural study of the secretory cells type 1 and 2 confirmed the separate identities of two secretory cell types in the gut of female B. microplus. Secretory cell type 1 (s1) synthesized and secreted large, spherical, uniformly electrondense granules. Secretory cell type 2 (s2) synthesized smaller, irregularly shaped and more complex granules. Another cell type, the basophilic cell, was shown to be the reorganized basal remnant of secretory cell s2. A few of the basophilic cells retained remnant s2 granules within their cytoplasm. In these cells the reorganized cisternae of rough endoplasmic reticulum were arranged in whorls and parallel arrays. The cells synthesized granules with a different ultrastructure and position in the cell from the earlier granules. The new secretory material may be egg proteins which are released into the haemolymph, and transported to the ovary. Another secretory cell type with smaller spherical granules was seen in the gut caeca of only two female ticks and more evidence is needed to prove its separate identity

Immunization of cattle against Boophilus microplus using extracts derived from adult female ticks: Histopathology of ticks feeding on vaccinated cattle

Immunization of cattle against Boophilus microplus using extracts derived from adult female ticks: histopathology of ticks feeding on vaccinated cattle. International Journal for Parasitology 16: 35-41. Histological examination of the tick Boophilus microplus fed on cattle vaccinated with tick extract showed that the gut was the primary site of damage. Within 24-48 h of attachment digest cells were either sloughed off into the lumen or were completely destroyed leaving only the basal lamina and muscle layer. Subsequent rupture of the gut allowed host leucocytes to enter the haemocoel and attack other tissues. After 6 days the surviving ticks showed a delay in development of digest cells and gut basophilic cells. Many host leucocytes had escaped into the haemolymph and these cells destroyed tick muscle and Malpighian tubules but not salivary glands. Females which survived to post-engorgement also had damaged gut cells. In males the histopathology of the gut was similar but the accessory gland of the reproductive organ was also damaged by host leucocytes. These effects on feeding ticks were not found on control cattle and have not been reported on animals with naturally acquired resistance to tick infestations. Vaccination apparently stimulated a different mechanism of resistance to ticks