Close relationship of Crimean hemorrhagic fever-Congo (CHF-C) virus strains by neutralizing antibody assays.

Strains of Crimean hemorrhagic fever-Congo (CHF-C) virus originating in widely separated points representing diverse zoogeograhiczl and ecological areas were compared by a neutralization of fluorescent foci of infection-test, in an attempt to determine whether antigenic differences could be detected among the strains. Minor differences were found which could be confirmed by reciprocal kinetic neutralization tests with one-injection immune sera if the results were analyzed by linear regression. However, CHF-C virus strains cannot be reliably subdivided into geographic variants on the basis of the minor antigenic variations observed. In this apparent paucity of antigenic diversity over its wide distribution, CHF-C virus differs from other arboviruses with similar or even lesser distribution.

Epidemiology of rabies in northern Nigeria.

Data on the rabies situation in Kaduna State, in northern Nigeria, were obtained by questionnaire and interview with all Divisional Veterinary Officers, physicians, hospital superintendents, village and hamlet heads or chiefs in various local government areas. All persons reporting animal bites to the Faculty of Veterinary Medicine, Ahmadu Bello University, Zaria, were also interviewed. Direct immunofluorescence staining, using both the regular conjugated anti-rabies globulin and a conjugated monoclonal antibody battery to lyssaviruses, was performed on brain samples from suspect animals sent to the Faculty of Veterinary Medicine. There were more dogs, and consequently more rabies outbreaks, in the southern part of the state than in the north; this did not appear to be associated with the religious beliefs of the local population. There seems to be a cyclic pattern of distribution of the outbreaks. Most dogs involved in bites had identifiable owners (74.5%), were older than one year (70.0%), and were not vaccinated (75.5%). Male children (under 10 years) were the high risk group for dog bites. Rabies cases seemed to cluster around April and September, corresponding to breeding seasons for dogs in Zaria. All the isolates checked by conjugated monoclonal antibodies for lyssaviruses were found to be rabies. Enforcing leash laws, vaccination of dogs against rabies especially before the breeding seasons, and control of stray and free-roaming dogs would reduce the incidence of rabies in Kaduna State.

Susceptibility of laboratory animals to experimental infection with Ife virus.

The susceptibility of rabbits, domestic chickens and albino rats to experimental infection with Ife virus was investigated. Neither pyrexia nor clinical signs of disease were observed in infected rabbits or chickens. Low-grade viraemia (10(1.0) mouse lethal doses per 0.02 ml) occurred in intracerebrally (i.c.) inoculated chicks on the second day post-infection. Complement-fixing antibody was detected on the 14th day post-inoculation in rabbits and on the 7th day in chickens. Infant rats less than 3 and 5 days of age died after subcutaneous (s.c.) and i.c. inoculation, respectively; older rats survived infection. Ife virus titres were highest in the brain following both i.c. and s.c. inoculation.

Immunosuppression and histopathological changes in the bursa of Fabricius associated with infectious bursal disease vaccination in chicken.

The effect of the infectious bursal disease (IBD) live virus vaccine on the immune response of chicken was evaluated by the assessment of antibody response following vaccination as well as resistance to challenge with virulent virus. Birds were vaccinated at various ages and later challenged with a heterologous vaccine (NDV) or wild-type IBD virus. The BF was examined for histological changes at regular intervals. Antibody levels to NDV were monitored. Significantly higher mortality rates were observed in birds vaccinated with IBD vaccine than unvaccinated birds (P less than 0.01) following challenge, BF from vaccinated birds showed marked lymphocyte depletion and cellular infiltration with mononuclear cells. Intraocular NDV (NDV-i/o) vaccine given at day old largely prevented the immunodepressive effect of IBD vaccination on NDV vaccine. Groups that received IBD vaccine on day 14 but no NDV i/o suffered higher mortality (41.2%) and showed lower antibody response than those vaccinated on day 1 (0%) or controls which did not receive IBDV (11.8%).

Scrotal dimensions and ejaculate characteristics of three breeds of sheep in tropical Nigeria.

Scrotal circumference and semen characteristics of three breeds of sheep (Udda, Balami and Yankasa) indigenous to Nigeria and Southern Guinea Savannah zones of Africa were compared. The age, body weight, scrotal circumference and spermiogram of the rams were studied by standard techniques. The mean age, body weight, and scrotal circumference of the three breeds were not comparable with significant interbreed, but were with significant intrabreed differences. The mean ejaculate concentration of sperm cells (x 10 /ml) were: Udda, 3.8 +/- 0.050, Balami, 4.1 +/- 0.32, Yankasa, 4.5 +/- 0.11. The mean morphological sperm cell abnormalities for the Udda, Balami and Yankasa were; 7.5 +/- 2.1%, 4.5 +/- 0.58% and 6.0 +/- 0.87%, respectively, with significant inter- and intrabreed differences. There were significant intrabreed differences in the other semen traits, i.e., percent of live cells, percent of motility, mean volume and mean concentration. In all the breeds of sheep studied, the scrotal circumference and spermiogram were comparable to, and within the range reported for the exotic breed of rams.

Prevalence of Ife virus infection in wild rodents and birds from Zaria, Nigeria.

One hundred eighty-three wild rodents and 38 wild birds trapped near Zaria were screened for virus and complement fixing (CF) antibody to Ife virus. Virus was not isolated but CF antibody was detected in 8% Cricetomys gambianus and 31% Arvicanthis niloticus tested. The presence of Ife virus has been documented now in three ecological zones of Nigeria.

Use of the enzyme-linked immunosorbent assay for screening cattle for Brucella antibodies in Nigeria.

The prevalence of Brucella antibodies in settled Fulani cattle herds in Kaduna State, Nigeria, was determined by using the enzyme-linked immunosorbent assay (ELISA) technique. Out of a total of 762 animals drawn randomly from 40 cattle herds in various areas of the state, 50 (6.6%) tested positive. There was no significant difference (P<0.01) in the number of reactors between male and female animals. Brucella antibodies were detected in animals in all areas of the state but prevalence was highest in Kaura area (26.8%) and was lowest in Zonkwa area (1.0%). Out of the 762 animals, 23 (3.0%) tested positive in the agglutination test (SAT) while 16 (2.1%) tested positive in the Rose-bengal plate test (RBTP). This study indicated that cattle in Nigeria have antibodies to Brucella tested by ELISA technique and that seropositive animals are located in distinct foci. The identification of these pockets of infection on a nation-wide basis will be crucial for future brucellosis control programmes.

Pathogenicity of Ife virus for Swiss albino mice.

Pathogenicity of Ife virus was studied in Swiss albino mice following four inoculation routes. Mice of all ages survived oral infection without seroconversion; subcutaneous (i.c.) and intraperitoneal (i.p.) infections lead to low titre antibody production. Only suckling mice (1-5 days old) succumbed to intracerebral (i.c.) inoculation with infectivity titres which decreased by age and average survival time (AST) increasing with age. Following i.c. inoculation to suckling mice, the brain infectivity titres increased progressively by days post-infection (p.i.). Virus was not recovered from the lungs and kidney but in low titre it was obtained from the liver, spleen, heart and blood at different days p.i. All organs examined showed evidence of complement fixing and immunofluorescent Ife virus antigen. No gross lesions were observed. The histopathological lesions were limited to the brain.

Development and use of real-time PCR to detect and quantify Mycoplasma haemocanis and "Candidatus Mycoplasma haematoparvum" in dogs.

Two canine haemoplasma species have been recognised to date; Mycoplasma haemocanis (Mhc), which has been associated with anaemia in splenectomised or immunocompromised dogs, and "Candidatus Mycoplasma haematoparvum" (CMhp), recently described in an anaemic splenectomised dog undergoing chemotherapy. The study aim was to develop quantitative real-time PCR assays (qPCRs) incorporating an endogenous internal control to detect Mhc and CMhp and to apply these assays to DNA samples extracted from canine blood collected in Northern Tanzania (n=100) and from dogs presented to a Trinidadian veterinary hospital (n=185). QPCRs specific for Mhc and CMhp were designed using 16S rRNA gene sequence data, and each was duplexed with an assay specific for canine glyceraldehyde-3-phosphate dehydrogenase (GAPDH). The assays detected < or =10 copies of a sequence-specific haemoplasma plasmid per reaction and neither assay showed cross-reactivity with 10(6) copies of the sequence-specific plasmid from the non-target canine haemoplasma species. Nineteen of the 100 Tanzanian samples (19%) were positive for Mhc alone and one (1%) was dually infected. One Trinidadian sample was negative for canine GAPDH DNA and was excluded from the study. Of the 184 remaining Trinidadian samples, nine (4.9%) were positive for Mhc alone, five (2.7%) for CMhp alone, and two (1.1%) dually infected. This is the first report of canine haemoplasma qPCR assays that use an internal control to confirm the presence of amplifiable sample DNA, and their application to prevalence studies. Mhc was the most commonly detected canine haemoplasma species.

Prevalence of antibodies to Crimean-haemorrhagic fever-Congo virus in cattle in northern Nigeria.

A seroepidemiological survey was carried out to determine the prevalence of antibodies to Crimean-haemorrhagic fever - Congo(CHF-C) virus among cattle in 3 ranches with varying degree of tick infestation. Sera were collected from 1164 animals and were tested by agar gel diffusion precipitation test (AGPT) for antibodies to CHF-C virus. About 25.7% of the sera had precipitating antibodies against CHF-C virus. There was no significant difference in the prevalence of antibodies between the ranches despite the varying degree of tick infestation.

Immunofluorescent staining of trypsinized formalin-fixed brain smears for rabies antigen: results compared with those obtained by standard methods for 221 suspect animal cases in Nigeria.

Formalin-fixed samples from 221 animal brains received for rabies diagnosis in Nigeria were digested in 0.1% trypsin in phosphate buffered saline, pH 7.4, and smears stained for rabies antigen by direct immunofluorescence (IF). The results were compared with those obtained using fresh material from the same animals for Negri body staining, mouse inoculation (MI) and occasionally immunofluorescent staining. From 191 specimens examined for Negri bodies and by mouse inoculation 51 and 64 respectively proved positive. The IF smear technique under investigation failed to detect 5 of these but showed up as positive 30 which had been recorded as Negri-negative and 19 that had gone undetected by MI too. In a direct comparison with IF staining of fresh tissue from 23 known rabies positive animals the similar staining of trypsin-digested formalized smears failed to give a positive result in 2 out of 23 cases. Some problems were encountered with smears not sticking to slides. When gelatinized slides were used fluorescence was sometimes poorer. Where transport and refrigeration are difficult and section-cutting equipment is lacking the technique of IF staining of smears prepared from formalized brain tissue after treatment with trypsin can be a useful adjunct to other diagnostic methods. It also makes for safer working where special facilities are absent.

Rabies in Oyo State, Nigeria; 1971-1982.

Epidemiologic data gathered from recorded sources in Oyo State, Nigeria, indicates that people are at 2.1 times greater risk there than in Africa generally and 56 times greater than in the United States of America of dying from rabies. Women older than 30 years of age comprised 45% (5/12) of the analyzable rabies cases from 1971 to 1979. Two of these 12 cases were contracted from cat bites and both of these cases were women. The reason for the high rate of rabies in Women (7/12), especially older women, is not known although this may relate to their socio-economic role in this part of Nigeria. Nor is it understood why women are more likely to be bitten by rabid cats. Eighty-seven percent of rabid animals were dogs. Males were at greater wisk of being bitten by an animal than were females at a ratio of 1.8 to 1, but 57% of male and 49% of female bite victims were 14 years of age or lress. Women 35-39 years old were bitten more frequently than would be expected from the dminishing rate displayed with increasing age, and this may explain, at least partially, their involvement in fatal rabies. There were an average of 45 to 50 cases of animal bites reported in Oyo State each month from January 1978 through December 1981, and a drastic rise was seen in January through April of 1980. There was not a parallel increase in human rabies during this 4 month period, however. A wildlife reservoir for rabies was not evident from the Oyo State data and it must be presumed that dogs are the maintenance reservoir for the virus. Questionnaire surveys were not useful during this study, but personal interview and trace-back efforts to gather information were valuable. These latter efforts suggest that rabies is more prevalent than existing records indicate, probably by a factor ranging from 2 to 6 or more. Rabies control in Oyo State will require recording and systematic reporting of human and animal cases to develop meningful programs. These all in turn revolve around the societal recognition and determination to cope with the problem.

The structure of the harderian gland of the guinea fowl at embryonic and post embryonic stages.

The Harderian gland of the guinea fowl is a bright, pink and relatively large orbital organ situated at the ventromedial aspect of the orbit. It possesses a single duct that has its exit on the convex medial surface. The outline is irregular with its caudal half narrower than the rostral half, and possessing a slight constriction about the mid point. Histologically, the gland had been outlined with the existence of a large contorted lumen by day 18 of incubation. The surface epithelial lining showed two layers of cells all through and lymphocytes were also present. By day 19 of incubation, certain zones of the surface epithelium had become pseudostratified and some of these cells contained vacuoles indicative of secretory materials within their cytoplasm. By day 21, few definitive acini with lumina had been observed and at day 23, the epithelium had assumed only a single layer of cells that were tall columnar cells, except at the junctions of the folds. By day 24, the tunica propria seemed to have completely disappeared with the acini occupying every available space. Plasma cells were seen three days after hatching.

The thymus of the guinea fowl from the eighteenth day of incubation until maturity.

The thymus gland of the guinea fowl appeared as a series of pink, irregular-shaped lobes along the jugular veins. These lobes were 13 in number with seven on the right and six on the left side. The third and sixth lobes on the right side were the largest. The largest lobe measured about 20.0 x 5.0 mm while the smallest measured about 5.0 x 4.0 mm. Histologically, it was encircled by a thin layer of poorly stained connective tissue from which strands penetrated the thymic tissue giving incomplete lobules peripherally as early as day 18 of incubation. Lymphocytes and reticular epithelial cells were the two types of cells occurring at this time. Reticular epithelial cells were observed to be vacuolated especially towards the centre of the gland. Macrophages were observed in the thymus on day 20 of incubation for the first time. The blood vessels had accompanied the interlobular septa into the thymus. By day 21 of incubation, blood vessels had actually penetrated the thymic tissue but most of these vessels were of the capillary size. The cortex also became quite distinct from the medulla. At day 22, vacuolation ceased to appear in the cells at the cortical zone. Macrophages were still less than 10 in the slide. At day 23, most blood vessels were within the medulla and they displayed compressed lumina. Mitotic figures became a common site amongst the large lymphocytes and reticular epithelial cells. By day one post-hatch, lobulation of the thymus was still poor and macrophages became difficult to identify. The small and medium lymphocytes had outnumbered the large lymphocytes throughout the thymic tissue except at the most peripheral zone of the cortex. Fine vacuoles had reappeared within the cytoplasm of the reticular epithelial cells in the cortex. By day five, the distribution of blood vessels was almost uniform between the cortex and medulla. At three weeks post-hatch, plasma cells and red blood cells were seen in the stroma of the gland for the first time and most of the red blood cells occurred in the medulla.

Haemagglutination inhibition antibody levels one year after natural measles infection and vaccination.

An assessment of haemagglutination inhibition antibody (HAI) titres of 1,163 children, comprising 739 recipients of live measles vaccines and 424 patients with natural measles infection after 1 year was made in this investigation. Statistical analysis revealed a significant difference in the levels of HAI antibodies. Of the vaccinated children a significant 67.45% showed antibody titres of less than or equal to 1:16, while only 23.48% of children with natural measles showed these antibody titres. The importance and implication of such HAI antibody titres is discussed.

A serological survey for Rift Valley fever antibody in food animals in Kaduna and Sokoto States of Nigeria.

A total of 1106 serum samples from cattle, sheep, goats and camels were collected from Kaduna and Sokoto States of Nigeria. These were tested for the presence of antibody to Rift Valley fever virus by the agar gel immunodiffusion method. The antibody prevalence rates were 2.85% in cattle, 6.67% in sheep, 0.98% in goats and 3.13% in camels.

Challenge study on infectious bursal disease in chicks derived from vaccinated hens.

Presence and levels of maternal antibody (MA) in broiler chicks derived from hens vaccinated with a live infectious bursal disease (IBD) vaccine were investigated by a quantitative agar-gel precipitin test. At day old 100% of the chicks tested had MA; by 17 days of age it was present in only 10%. The mean MA level at day old was 337.5 UK units/ml but decreased to 6.3 UK units/ml at 17 days of age. Randomly selected chicks from the pool studied were challenged at weekly intervals from day old for 29 days with an IBD virus obtained from a natural outbreak. Subclinical and clinical disease were observed in chicks challenged at eight and 29 days of age respectively.

Serological evidence of Ife virus infection in Nigerian indigenous domestic ruminants.

Serological evidence of Ife virus infection was observed in cattle, sheep, goats and camels in both ecological zones of Sokoto and Kaduna States of Nigeria. The antibody prevalence rates differed between species and between zones, being highest in the guinea savanna. This is the first report of possible Ife virus infection in domestic ruminants.

Vaccination challenge studies with variants of street rabies virus isolated in Nigeria.

In a preliminary study it was observed that adult ICR mice immunized with serial dilutions of an inactivated experimental human rabies vaccine from the Pitman-Moore (PM) vaccine virus were well protected against challenge with homologous virulent PM virus and challenge virus standard (CVS). However only one of five variant representatives in five of seven groups of 41 isolates of street rabies virus from Nigeria characterized by hybridoma monoclonal antibodies specific for the nucleocapsid and glycoprotein antigens of rabies virion was protected for by the vaccine. Guinea pigs immunized with a live attenuated low egg passage (LEP, Flury strain) vaccine currently used in canine vaccination in Nigeria protected against challenge with all five variants. The LEP vaccine protected against the variants and CVS quite well even when 1:125 dilution of the vaccine was used.

The anatomy of the cloacal bursa (bursa of Fabricius) in the helmeted guinea fowl (Numida meleagris galeata).

The cloacal bursa (bursa of Fabricius) in the guinea fowls appeared either as an oval blind sac with a short thick stalk in one group or had a pointed cranial blind end with a slightly bulging middle part that was followed by a thick caudal stalk in the other group. Both groups of bursae originated from the proctodeal wall of the cloaca and were placed dorsal to the rectum. The average length of the bursa was 18 mm while the average width at the mid section was 15 mm. The internal surface showed about 12-14 primary folds. Histologically, the outline of the bursa was well established by day 18 of incubation. The primary folds had also been formed. Lymphocytes had already been encountered within the framework of the bursa at this day. The epithelium bordering the tunica propria was composed principally of two layers of cuboidal cells. Epithelial buds had also formed and some were already detached from the epithelial lining. The blood vessels present were positioned just beneath the outer covering. At day 19 of incubation, most of the epithelial buds had two layers of cells arranged in a circumscribed manner while a few had three layers of cells. Blood vessels had increased in number and were deeper placed inside the bursa than previously. At day 20, the cells of the upper layer of the epithelium were dorsoventrally flattened and stained paler than the cells of the lower layer. It was possible to distinguish the cortex from the medulla and the basement lining between both zones was distinct. Tiny vesicles within the cytoplasm of the epithelial cells at the mucosa and follicles were observed. Macrophages were also observed within the gland. At day 21, blood vessels were observed in the cortex of the follicles. The maximum number of primary folds (14) had been formed. At day 22, several follicles had severed connections with the mucosal epithelium. The mucosal lining had dropped to a single layer of cells in some areas. Goblet cells were observed amongst the mucosal cells. A plasma cell had first appeared. By day 25, dead cells had increased quite in number and there was also an increase in number of medium and small-sized lymphocytes within the gland. By day 26, the upper layer of the surface epithelium was composed primarily of tall columnar cells with numerous large vacuoles. Macrophages had suddenly increased within the thin interfollicular spaces and most of them were crowded internally with various sizes of debris.(ABSTRACT TRUNCATED AT 400 WORDS)