Prevalence of intestinal helminth parasites of pigeons (Columba livia domestica Gmelin 1789) in Kano State, North-Western Nigeria.

In Nigeria, helminths have over the last decades been established as important parasite of poultry including pigeons. However, the prevalence of these parasites of pigeons in Kano State is yet to be established. The prevalence of helminth parasites of domestic pigeon (Columba livia domestica) in Kano State, Nigeria was investigated in this study. The differences in the prevalence of infection between the pigeons examined on the basis of sex of the pigeon and season of the year were analyzed statistically using the students' "t" -test. The intestinal contents of 144 pigeons were examined for gastrointestinal helminths between February and April representing the dry season and between June and August for the wet season. Pigeons were grouped according to Squabs (chicks) (0-4 weeks), Squeakers (Juveniles) (5-8 weeks) and Youngsters (Adults) (9 weeks onwards). Intestinal parasites found include Cestodes: Raillietina tetragona, 20 (13.80%), R. echinobothrida, 11 (7.64%), Amoebotaenia cuneata, 5 (3.47%), Hymenolopis contaniana, 10 (6.95%), Davainea proglottina, 1(0.69%) and Ornithostrongylus quadriatus 1(0.69%). Nematodes: Capillaria obsignata, 10(6.95%) and Ascaridia columbae, 9(6.25%). Forty-two (29.16%) of the birds had mild infection, 17 (11.81%) had moderate infection, 9 (6.25%) and 2(1.39%) had heavy and severe infection, respectively. The prevalence was higher during the wet season (36.65%) than during the dry season (27.97%). Of all the age groups, only Youngsters, 34 (23.61%) were infected with intestinal helminths. However, there were statistically significant differences between the age, sex and seasons in this study (P < 0.005). Pigeons raised on semi-intensive had the highest rate of infection (37.50%) and those raised on intensive management had the lowest rate of infection (9.03%). A number of measures are recommended for the control of these helminthic parasites.

Anti-trypanosomal effects of aqueous extract of Ocimum gratissimum (Lamiaceae) leaf in rats infected with Trypanosoma brucei brucei.

The anti-trypanosomal effects of aqueous extract of the leaf of Ocimum gratissimum were evaluated in both in-vitro and in-vivo studies. The anti-trypanosomal activity of the extract against Trypanosoma brucei was investigated in-vitro. The survival and motility of the trypanosomes were completely inhibited within two hours of incubation in various concentrations of the extract. Parasite survival time was concentration dependent being longer in lower (25 and 12.5 mg/ml) than higher (100, 75 and 50 mg/ml) concentrations of the extract. The in-vivo anti-trypanosomal effect of the leaf extract of the leaf extract was investigated in rats infected with Trypanosoma brucei and treated with the extract. The infected rats treated with the extract had less dramatic clinical manifestations and mortality, survived longer and higher PCV values than their untreated counterparts, however, parasitaemia was not significantly reduced. The results suggest that the folkloric medicinal application of the aqueous extract of Ocimum gratissimum has no possible pharmacological basis.

The incrimination of Aedes (stegomyia) aegypti as the vector of Dirofilaria repens in Nigeria.

Six local species of culicides were identified as the common mosquitoes in Zaria, out of 15 species captured using various adult and larval collection methods. These common culicides are Culex pipiens fatigans, Anopheles gambiae grp., Mansonia africana, Culex pipiens pipiens, Aedes (stegomyia) aegypti and Aedes vittatus. They were each fed directly on a local dog naturally infected with Dirofilaria repens to evaluate their refractoriness/susceptibility to dirofilarial infection. In a number of donor-feeding trials, 39. 4% Culex pipiens fatigans; 58.9% An gambiae grp.; 60.5% Mansonia africana; 1.8% of Culex pipiens pipiens; 23.4% Ae aegypti and 3.3% of Ae vittatus successfully fed on the microfilaraemic host. Only Aedes aegypti was susceptible to the infection as all 40 (100%) Ae aegypti reaching 10-14 day post-blood meal had infective (L(3)) larvae of D. repens. The remaining five species were refractory. The microfilariae in the five non-susceptible mosquitoes were always found trapped in the blood meal in the insects midgut (stomach). These trapped microfilaria were dead by the 2nd day in the insect's midgut. However, in the susceptible Ae aegypti, the microfilariae were set free from the blood meal in the midgut and within 24h migrated to the malpighian tubules (MT) of the mosquitoes. All Ae aegypti dissected 5-7 day post-infective blood meal showed the typical quiescent sausage stage (L(2)) larvae in the malpighian tubules. At day-10 post-blood meal, relatively active infective (L(3)) larvae of D. repens were found in the MT; and by day 12-14, highly motile infective larvae had reached the insect's head and proboscis, with infective larvae occasionally oozing out during dissection through the tip of the proboscis. The rate of development of D. repens to infective larvae was faster in mosquitoes infected in July when the environmental temperature was 24.5 degrees C than those infected in November when the temperature was 22.5 degrees C. The latter were delayed for 4 days. The breeding sources of Ae aegypti, the local vector implicated were also identified. As no particular vector of this zoonotic filaria has been identified previously in Nigeria, these findings could make any control programme more focussed and easier.

Effects of acute bovine trypanosomosis (Trypanosoma vivax) on plasma kinetics of intravenously administered lactose.

Four calves infected with Trypanosoma vivax and four uninfected control calves were each injected intravenously with repeated doses of 0.5 g lactose kg-1 body weight, thrice daily at intervals of 4 h. Plasma samples were collected at specified time intervals and analysed for lactose. Pharmacokinetic parameters were calculated from the data. T. vivax infection delayed excretion of lactose from the body, thus leading to significantly (P < 0.001) increased biological half life (t1/2) and a significantly (P < 0.001) reduced elimination rate constant for lactose in the body. The apparent volume of distribution and total clearance of lactose were not affected by the infection. T. vivax infection also appeared to cause accumulation of lactose in the plasma after repeated intravenous administration.

Studies of experimental infection and cross-immunity between stocks of Cowdria ruminantium in Sokoto red goats.

The course of experimental infection and cross-immunity tests between stocks of Cowdria ruminantium were investigated using eight infected and four uninfected control Sokoto red goats. All eight infected goats reacted to the primary infection. The incubation period varied between 8 and 23 days. During the febrile reaction, the highest rectal temperature recorded was 40 degrees C and the lowest was 39.7 degrees C, compared with a range of 38.6 +/- 0.15 to 38.1 +/- 0.19 in control goats. Following the primary infection, each of the animals was treated with long-acting Tetracycline (Terramycin, Pfizer) at a dose of 20 mg kg-1 body weight to control the resulting temperature reaction. They were reinfected with the homologous stock 3 weeks after treatment to demonstrate whether they had become immune. The homologous challenge did not give any temperature reaction during 3 weeks of monitoring. They were then challenged with the heterologous C. ruminantium stock. This did not result in a febrile reaction during 3 weeks of monitoring. The observed cross-protection indicates antigenic similarity between the two stocks.

Boophilus microplus (ixodid tick): fine structure of the gut basophilic cell in relation to water and ion transport.

Basophilic cells in the guts of female ticks are derived from the basal remnants of type 2 secretory cells. As viewed by electron microscopy, these cells have microvilli uniformly distributed on the luminal surface, but they lack the abundant pinocytotic vesicles and lysosomes characteristic of digest cells. The cytoplasm is filled with well organized rough endoplasmic reticulum, Golgi complexes and secretory granules. Infoldings of a basal labyrinth extend the contact of the cell with the underlying haemolymph, and there are many mitochondria in the cell processes between folds. This morphology appears to fit the cell for functioning in active water transport across the gut wall. Subsequent to a final rapid phase of engorgement, the basophilic cell reorganizes its cisternae of rough endoplasmic reticulum into whorls and parallel arrays and resumes a secretory role.

Scanning electron microscopy of digest cells in the midgut epithelium of Boophilus microplus.

Scanning electron microscopy showed the presence of microvilli on the digest cells, but more importantly, it showed that the gut could be everted to expose the lumen surface of the cells to molecular analysis. X-ray microanalysis demonstrated the presence of iron and sulphur in the haematin granules within spent digest cells, confirming that these granules are end products of blood digestion in adult ticks.