Diseases of indigenous chickens in Bokaa village, Kgatleng district, Botswana.

This study examined flock size and management, level of internal and external parasite burden and seroprevalence of antibodies to poultry pathogens in indigenous chickens in Bokaa village, Kgatleng district, Botswana. The mean flock size was 22.6 +/- 6.85 with a range of 11-34. The mean body weights of cocks and hens were 2.28 +/- 0.56 kg and 1.70 +/- 0.38 kg, respectively. Housing and commercial poultry feed were not provided. Ascaridia galli, Heterakis gallinarum and Syngamus trachea were found in some birds. Although the chickens were not vaccinated against any poultry diseases, serum antibodies to Newcastle disease, infectious bursal disease and infectious bronchitis were detected.

Effect of malignant catarrhal fever virus infection on the immune response of rabbits to sheep red blood cells.

Rabbits infected with African Malignant catarrhal fever virus mounted a depressed antibody response to sheep red blood cells compared to the antibody response of uninfected rabbits. Immunodepression was observed in rabbits immunised 0, 3, 5, 7 and 10 days after infection. Antibody response was not depressed in the rabbits immunised 1 day after infection. Despite the depressed antibody response to SRBC, the rabbits died with rising virus neutralising antibody to the virus. The possible causes of the immunodepression are discussed.

Malignant catarrhal fever virus specific secretory IgA in nasal secretions of wildebeest calves.

Wildebeest IgA was isolated from nasal secretions and precolostrum. It was identified by cross-reaction with anti-human and anti-bovine IgA sera. Nasal secretions collected from wildebeest calves over 3 months old had malignant catarrhal fever virus neutralizing antibody activity. They also contained specific IgA to the virus as detected by indirect immunofluorescence. It is suggested that production of malignant catarrhal fever virus specific IgA in the nasal cavity, contributes to the elimination and cessation of the virus shed in the nasal secretions of wildebeest calves over 3 months. old.

Antibodies in carrier wildebeest to the lymphoproliferative herpesvirus of malignant catarrhal fever.

Six types of antibody to malignant catarrhal fever virus (MCFV) were measured in 132 sera collected from Wildebeest in Kenya Masailand. The titre of all types of antibody declined slowly with increasing age of the wildebeest. A significantly greater proportion of wildebeest calves had higher titres of antibodies to MCFV early antigens, IgM antibodies to MCFV late antigens and complement-fixing antibodies, than did older animals. One seronegative calf, reared in isolation without colostrum, became seropositive 4 1/2 weeks after birth but did not show any clinical signs indicative of MCFV infection. Similarities between MCFV infection of wildebeest calves and other inapparent infections with lymphoproliferative herpesviruses are discussed.

Isolation of Theileria taurotragi and Theileria mutans from cattle in Botswana.

Two Theileria species demonstrated in peripheral Giemsa-stained blood smears of sick cattle from various parts of Botswana were subsequently identified as Theileria mutans and T. taurotragi using DNA hybridization and the polymerase chain reaction. Initial screening for Theileria species was done using microscopy, the indirect fluorescent antibody technique and the micro Elisa test. The syndrome was characteristically that of high morbidity but low mortality and vague malaise. A low parasitaemia of pleomorphic intra-erythrocytic piroplasms and the absence of schizont stages in circulating lymphocytes and lymph node aspirates were evident. Dual infections were common and often complicated by intercurrent disease conditions.

Impaction of the stomachs in farmed ostriches (Struthio camelus) in Botswana.

Impaction of the proventriculus, gizzard, and sometimes intestines due to sand was confirmed at postmortem in 25 cases involving ostriches (Struthio camelus). Although there was no age predisposition, impaction was more common in juvenile over 3 mo old. Clinical signs included sternal recumbency, outstretched neck, debility, and inability to stand. Palpation of the impacted stomachs gave a gritty sensation. Depletion of coronary fat was a consistent postmortem finding. The most common material causing impaction was sand. This report highlights impaction as one of the major causes of debility and death in intensively farmed ostriches. High levels of alkaline phosphatase coupled with low levels of plasma glucose, protein, and albumin detected in impacted ostriches may be useful diagnostic antemortem indicators of the syndrome.

A microtitre technique for the assay of malignant catarrhal fever virus and neutralising antibody.

A microtitre technique for the quantal assay of a cell-free strain of malignant catarrhal fever virus was developed, using serially passaged bovine embryonic kidney cells. End-points were determined after 12 days' incubation and the mean titre recorded for a single virus stock stored at -70 degrees C over a six-month period was 10(5.5) +/- 0.2 (SD). In neutralisation tests serum/virus mixtures were best held at 37 degrees C for 1 h in microtitre trays before the addition of cells; assays were highly reproducible, figures of 10(1.5) +/- 0.2 being obtained for a single reference serum.

Reaction of goats to infection with infectious bovine rhinotracheitis virus.

Intranasal exposure of goats to infectious bovine rhinotracheitis virus resulted in mild respiratory disease and virus reisolation from nasal secretions. No disease was produced in goats exposed to the same virus by the genital or ocular routes. There was serological evidence of contact transmission of infection from infected goats to cattle. Virus recrudescence was not detected in goats treated with dexamethasone two months after virus inoculation.

Antibody response in cattle and rabbits to early antigens of malignant catarrhal fever virus in cultured cells.

Cytosine arabinoside (Ara-C) inhibited the production of late antigens and of infectious virus in monolayers of bovine kidney cells infected with the high-passage, WC-11 strain of malignant catarrhal fever virus. Early antigens were not affected. Using hyperimmune and acute-phase sera from cattle and rabbits in indirect immunofluorescence tests, it was shown that Ara-C treated cultures contained two early antigens; one was diffuse and distributed throughout the cells, the other was particulate and intranuclear. Antibody to early antigens developed later and attained lower titres in infected animals, especially rabbits; only hyperimmune sera reacted with the diffuse early antigen.

Isolation of bovine malignant catarrhal fever virus from ocular and nasal secretions of wildebeest calves.

Malignant catarrhal fever (MCF) virus was isolated from ocular secretions of four out of nine free-ranging wildebeest calves, while four out of 11 animals had the virus in nasal secretions. The mean infectivity of virus in ocular and nasal secretions was 10(2.25)TCID50/ml and 10(2.5)TCID50/ml respectively but infectivity of more than 10(3.2)TCID50/ml was found in some ocular and nasal secretions. Thus it appears that MCF virus is excreted via the ocular and nasal routes from wildebeest calves, and the presence of high titre virus supports the suggestion that MCF virus is disseminated by these secretions. This virus was not recovered from urine or saliva.

Antibodies to malignant catarrhal fever virus antigens in the sera of normal and naturally infected cattle in Kenya.

Six different serological tests were used to examine Kenyan cattle sera for antibodies to the herpesvirus of malignant catarrhal fever. Significantly higher levels of indirect immunofluorescent antibody to early and late virus antigens and of complement fixing antibody were found in the sera of 13 naturally infected cattle than in 482 sera collected from four different groups of normal cattle. Virus neutralising and immunoprecipitating antibodies were also found in some infected cattle sera but not in normal cattle sera. Many non-specific reactions occurred using counterimmunoelectrophoresis. These preliminary results indicate that the serological diagnosis of wildebeest-associated malignant catarrhal fever may be possible.

The effect of Trypanosoma congolense and T vivax infections on the antibody response of cattle to live rinderpest virus vaccine.

Infections with Trypanosoma congolense or T vivax did not significantly depress the neutralising antibody response of cattle to live rinderpest vaccine when vaccination was carried out eight or 25 days after infection.

Experimental infection of wildebeest with the herpesvirus of infectious bovine rhinotracheitis/infectious pustular vulvovaginitis.

Intravaginal inoculation of a wildebeest (Connochaetes taurinus) with a wildebeest strain of the infectious bovine rhinotracheitis/infectious pustular vulvovaginitis herpesvirus induced only mild vulvovaginitis. The same virus did not produce any disease in another wildebeest exposed intranasally. A wildebeest bull which was inoculated by preputial instillation developed mild posthitis. The virus was reisolated only from the sites of inoculation. A carrier state was initiated in a wildebeest inoculated only once, intravaginally. The presence of this virus in the various secretions is a potential source for venereal transmission.

Observations on the epidemiology of the herpesvirus of infectous bovine rhinotracheitis/infectious pustular vulvovaginitis in wildebeest.

Spontaneous vulvovaginitis erupted in wildebeest (Connochaetes taurinus) after betamethasone inoculation. Infectious bovine rhinotracheitis/infectious pustular vulvovaginitis (IBR/IPV) is probably a venereal disease because virgin wildebeest did not develop vulvovaginitis after betamethasone injections, nor was the virus transmitted to these virgin wildebeest and steers which were in pen contact with the affected animals. A domestic bovine heifer developed mild IPV and became a virus carrier, when exposed to the wildebeest IPV virus by vaginal instillation.

Effect of anti-thymocyte serum on acquisition of resistance to infestation by Rhipicephalus appendiculatus larvae in rabbits.

Administration of specific goat anti-thymocyte serum (ATS) to rabbits, prior to a primary infestation by Rhipicephalus appendiculatus larvae, blocked the acquisition of resistance significantly only in the third infestation. The larvae which fed on these rabbits had higher engorgement masses than did those feeding on untreated control rabbits. Also, a higher percentage (92%) of larval ticks fed on these animals than on the controls (88%). ATS also induced a leucopenia due to a lymphopenia in the treated rabbits. It was concluded that a T-cell-dependent component might be involved in acquired resistance to infestation by R. appendiculatus.

Yolk sac utilization in ostrich (Struthio camelus) chicks.

The mass of residual yolk sac expressed as a percentage of initial mass of the egg from which the chick hatched decreased sharply in the first 2 days post-hatching. A gradual reduction occurred between 3 and 10 days after which a sharp decline was noted between 11 and 13 days post-hatching. The highest number of chicks with unabsorbed yolk sac was noted on day 5 post-hatching followed by days 6 and 7. Chick mortality followed the same pattern. The dynamics, causes and clinical consequences of yolk sac utilization are discussed.

Effect of cyclophosphamide on the acquisition of resistance to infestation by Rhipicephalus appendiculatus in rabbits.

Parenteral administration of cyclophosphamide in rabbits made resistant to infestation by the tick Rhipicephalus appendiculatus, resulted in abrogation of the resistance phenomenon. As a result, a high percentage (83%) of the larval ticks fed to repletion. This was in contrast to the control rabbits which were expressing the phenomenon of resistance to infestation by the ticks. In the latter, only 28% of the ticks fed to repletion. Cyclophosphamide administration in rabbits induced a leucopenia and depressed antibody response to the heterologous antigen, sheep red-blood cells.

Serum biochemical values of farmed ostrich (Struthio camelus) in Botswana.

Reference biochemical values for serum analytes of 126 clinically normal farmed ostriches on one farm in Botswana were established. These included sodium, potassium, chloride, total protein, albumin, urea, creatinine, uric acid, cholesterol, total bilirubin, conjugated bilirubin, glucose, triglyceride, calcium, phosphorus, manganese, copper, zinc, alkaline phosphatase, gamma glutamyl transferase and creatinine kinase. The values obtained in this study can be used as reference values.

Helminth parasites of domestic pigeons (Columba livia domestica) in Sebele, Gaborone, Botswana.

Twelve adult domestic pigeons from Sebele, Gaborone, Botswana, were examined for the presence of helminth parasites. The cestode genus Raillietina and two species of nematodes, Dispharynx spiralis and Ascaridia columbae were recovered. Most pigeons (75 %) were infected with Raillietina spp. often in concurrence with A. columbae.

Seroprevalence of Toxoplasma gondii and Chlamydia psittaci in domestic pigeons (Columbia livia domestica) at Sebele, Gaborone, Botswana.

High antibody titres to Toxoplasma gondii and Chlamydophila psittaci were demonstrated in serum collected from domestic pigeons at average titres of 1:128 and 1:64 respectively. The public health implications of these findings are discussed.