Canine filariasis in Zaria, Nigeria.

Microscopic examination of blood samples from dogs in Zaria, Nigeria indicated the prevalence of canine filariasis to be 12.7%. The survey demonstrated three species of canine filariae, namely D. repens (8.9%). D. immitis-like parasite (2.5%), and an unidentified species of filaria with a prevalence of 4.4%.

Ultrastructure of the alimentary tract of third-stage larvae of Litomosoides carinii.

The ultrastructural morphology of the alimentary tract of the third-stage larvae of Litomosoides carinii (Nematoda: Filarioidea) is described. The oesophagus possesses the characteristic tri-radiate lumen and is lined by cuticle. Teh lumen of the oesophagus is tightly occluded anteriorly by particulate material and posteriorly at the oesophagointestional junction. Three glands are present in the glandular region, one dorsal and two subventral. These glands contain secretory granules with similar morphological and staining properties. The lumen of the intestine is ill-defined without microvilli and apparently non-functional. It is likely that the larvae feed via the transcuticular route.

Adrenal and thyroid dysfunctions in experimental Trypanosoma congolense infection in cattle.

Severe pathological changes were observed in the adrenal and thyroid glands of Zebu (Bos indicus) heifers infected with Trypanosoma congolense. In the adrenal glands, severe inflammatory changes characterised by mononuclear cellular infiltration in the subcapsular areas, zona glomerulosa, zona fasciculata and zona reticularis were observed. In addition, there were hyperaemia, haemorrhage and hyperplasia resulting in increased adrenal weight in the two heifers slaughtered on Days 50 and 70 post-infection (p.i.). In the medullary areas of these two heifers, there was only mononuclear cellular infiltration. In the two heifers slaughtered on Day 113, localised mononuclear cellular infiltration was observed in addition to cortical cell depletion and fibrosis, resulting in reduced adrenal weight when compared with the controls. In the thyroid glands of the infected heifers, gross enlargement of the follicles filled with pale staining colloids were observed in association with squamous metaplasia of the follicular epithelium and fibroplasia. Serum cortisol concentrations showed an appreciable but non-significant increase (P less than 0.05) between Weeks 2 and 6 p.i. in the infected heifers (5.6 +/- 0.86 ng ml-1 vs. 4.4 +/- 0.34 ng ml-1) when compared with the uninfected controls or the pre-infection level. Thereafter, cortisol levels declined though non-significantly throughout the rest of the study. However, there was a steady increase towards normal levels from Week 12 p.i. until the end of the experiment. Changes in the basal serum concentrations of thyroxine (T4) were also measured weekly. There was a progressive decrease in the levels of T4 from the third until the 11th week p.i., when the decrease became significant (P less than 0.05) and remained so until the 16th week when the experiment ended.

Observations on third-stage larvae and adults of Litomosoides carinii (Nematoda: Filarioidea) by scanning and transmission electron microscopy.

The morphology of the body wall of the infective third-stage larvae and adults of Litomosoides carinii was studied by scanning and transmission electron microscopy. The mouth of both stages is surrounded by four inner papillae and two outer papillae; a pair of amphidial glands open laterally between the inner papillae. Female larvae and adults have two lateral caudal papillae; male larvae have a single ventral one, and adult males have two ventro-lateral lines of caudal papillae. The larval cuticle is two-layered, with fibres in the inner layer, whereas the adult cuticle has four layers apparently traversed by channels. Except for the chordal regions, larvae and adults both have an exceptionally thin hypodermis which is separated from both the cuticle and the underlying muscle cells by highly-convoluted membranes. The dorsal and ventral hypodermal chords contain nervous tissue, whereas the lateral hypodermis contains mainly mitochondria, golgi and micro-organisms. The muscle cells of larvae and adults contain thick and thin myofilaments arranged parallel to the long axis of the worms. In larvae each section has nine to 12 muscle cells, each of which has an inner non-sarcoplasmic zone containing the nucleus. The muscle cells of adult worms, although fewer in number, are more complex, and those of male worms in particular have lamellae which are deeply invaginated to form dense rectangular bands. Glycogen and lipid droplets are absent from larval muscle cells, whereas they are present in those of adult worms.

Comparative studies of gastrointestinal helminths of poultry in Zaria, Nigeria.

Two-hundred and ten digestive tracts of local chickens reared in and around Zaria, Northern Nigeria, under the extensive native free range system of management and 203 digestive tracts of exotic chickens raised under the intensive system of management were examined for parasites. Two hundred and one (95.7%) of the local chickens were infected and 24 (11.8%) of the exotic chickens also. Among the local chickens, 12 species of nematodes and 7 species of cestodes were recovered. Only one nematode and one cestode species were recovered from the exotic chickens. The prevalence of helminth infections between local and exotic chickens was significantly different at 1%.

Prevalence of Sarcocystis species in sheep and goats in northern Nigeria.

Tissue samples comprising the oesophagus and diaphragm were collected from 400 sheep and 400 goats slaughtered at the abattoirs in the study area. Out of this number, 36 were positive for Sarcocystis cysts (sarcocysts) in sheep and 56 in goats. The sarcocysts in sheep measured 35.7 to 500 microns lengthwise and the cyst-wall 2.4 microns. They were identified to be Sarcocystis tenella. The cysts in goats measured 98 to 700 microns and the cyst-wall 2.7 microns. They were identified to be Sarcocystis capracanis. In both animals species, the sarcocysts were more frequent in the oesophagus than in the diaphragm. All sarcocysts seen were microscopic.

Prevalence of microfilariae in cattle at slaughter in Zaria, Nigeria.

Skin snips and blood taken from 372 randomly selected slaughtered cattle in Zaria, Nigeria were examined for microfilariae. A total of 293 (78.8%) skin snips and 218 (58.6%) blood samples were positive for microfilariae. Two types of microfilariae, identified as Onchocerca armillata, with a percentage prevalence of 64%, and O. gutturosa with a prevalence of 40% were isolated from the skin. The blood microfilariae were identified as those of Setaria labiatopapillosa.

Susceptibility of two-week old Lymnaea natalensis to some plant extracts.

The molluscacidal potency of 17 Nigerian plants extracted by the unevaporated crude water (UECW) method was evaluated on two-week old Lymnaea natalensis Krauss. Five extracts were not active but extracts of Balanites aegytiaca, Blighia sapida, Boswellia dalzielii, Cissampelos mucronata, Detarium microcarpum, Kigelia africana, Opilia celtidifolia, Parkia clappertoniana, Polygonum limbatum, Pseudocedrela kotschyi, Nauclea latifolia and Securidaca longipedunculata were molluscacidal. There is potential for their future use in the integrated control of Lymnaea natalensis, as well as other snails. Mortality data for lethal concentration values for all extracts were analysed by use of probit transformation. The upper and lower fiducial limits of the LC50 (P = 0.05) were also determined.

Screening of some Nigerian plants for molluscicidal activity.

Methanolic (MEOH), evaporated crude water (ECW) and unevaporated crude water (UECW) extracts of 25 Nigerian plants, used for different medicinal and domestic purposes were screened for molluscacidal activity on laboratory-reared Lymnaea natalensis Krauss. Seven of the plants were not active; extracts from 18 (72 per cent) of the plants, some of which are renowned fish poisons, had molluscicidal activity. These were Acacia nilotica, Aristolochia albida, Balanites aegyptiaca, Blighia sapida, Boswellia dalzielii, Detarium microcarpum, Gnidia kraussiana, Kigelia africana, Nauclea latifolia, Opilia celtidefolia, Parkia clappertoniana, Polygonum limbatum, Pseudocedrela kotschyi, Sclerocarya birrea, Securidaca longipedunculata, Ximenia americana, Vetiveria nigritana and Ziziphus abyssinica. The LC50 of these extracts were determined. It is strongly recommended that the toxic effects of these extracts against fish, cercariae, snail eggs and mammals be further investigated so as to determine the right concentration, especially for use in fish ponds.

In-vivo encapsulation and killing of Litomosoides carinii in white rats.

Ultrastructural studies revealed that in albino rats Litomosoides carinii was encapsulated and eventually killed in the pleural cavity by adherent host cells. Encapsulation was an organized cellular reaction which sequestered and eventually degraded the parasites. The process evolved in three phases: primary accumulation of host cells, especially eosinophils and macrophages, around the parasites with concentration of eosinophils on the parasite surface; secondary transformation of macrophages into epithelioid cells which replaced eosinophils on the parasite surface; finally, dead parasites became calcified and were gradually degraded within a tough, compacted fibrotic capsule.