Identification of an immunodominant antigenically conserved 32-kilodalton protein from Cowdria ruminantium

Western blotting (immunoblotting) of Cowdria ruminantium antigens with goat or mouse antiserum identified a periodate-resistant, proteinase K-sensitive immunodominant antigen of 32,000 daltons. This protein, designated Cr32, could be demonstrated in goat choroid plexus infected with one of two different Cowdria stocks. Antisera against nine different Cowdria stocks from Africa and the Caribbean region recognized Cr32, which indicates that this protein contains conserved antigenic determinants.

Epidemiology of bovine babesiosis and anaplasmosis in Zambia

The serological prevalence of bovine babesiosis and anaplasmosis in the traditional farming sector of six provinces of Zambia was determined using the indirect fluorescent antibody test (IFAT) for babesiosis and the card agglutination test (CAT) for anaplasmosis. Antibodies to Babesia bigemina occurred throughout the country whereas the prevalence of B. bovis followed the distribution of its tick vector Boophilus microplus which is limited to the north-eastern part of the country. Low numbers of B. bovis serologically positive cattle were demonstrated in central and southern Province. Anaplasma spp. occurred throughout Zambia but the overall percentages of positive sera were low ranging between 14.7% and 38.6% using the CAT. Two hundred sera were retested for anaplasmosis using an enzyme-linked immunosorbent assay (ELISA). Sero-prevalence rates were 1.5 to 2.3-fold greater with the ELISA than with the card agglutination test.

Antigenic differences between stocks of Cowdria ruminantium

Stocks of Cowdria ruminantium from Senegal, Zambia and South Africa were compared in cross immunity tests in goats. The Senegal stock caused fatal heartwater in three of 10 goats immune to the South African reference stock Ball 3, and five others showed significant febrile reactions and recovered spontaneously. Four goats immune to the Senegal stock did not show any reaction on challenge with Ball 3. The stock from Zambia was fully cross-protective with Ball 3 in experiments with three goats, but these three goats, immune to the Zambia stock and to Ball 3, showed severe febrile responses upon further challenge with the Senegal stock. The Senegal stock was highly virulent for Dutch goats and there were exceptionally large numbers of rickettsiae in brain capillaries after death. This stock has been passaged eight times in mice, without causing disease; the presence of the organism in the mice was shown by subinoculating goats. The Senegalese stock of C ruminantium is the first stock outside South Africa against which the reference Ball 3 stock does not fully immunise.

Quantitative correlation of parasitological and serological techniques for the diagnosis of Trypanosoma congolense infection in cattle

A comparison was made between serological and parasitological techniques for the diagnosis of bovine trypanosomiasis in Zambia. Overall sero-prevalence rates as determined by IFAT and ELISA were respectively 2.7-fold and 2.9-fold greater then the percentage of samples found positive with the dark ground/phase contrast buffy coat technique (DG). The results obtained by the two serological techniques were found to be closely correlated (94.2%) agreement) and titres obtained by ELISA tended to be slightly higher than those obtained by IFAT. Linear regression analysis of the results obtained by the IFAT and DG techniques revealed a highly significant correlation. This finding would permit the use of only one of the techniques in an epidemiological survey and to extrapolate the results from the regression line.

Theileria taurotragi in Zambia

Theileria sp. (Bwengwa) of low virulence was isolated by feeding R. appendiculatus ticks collected from the field on a susceptible calf and subsequently transmitted between cattle by R. appendiculatus ticks- Theileria sp. (Bwengwa) was shown to be T. taurotragi on parasitological, clinical and serological grounds. T. taurotragi is the fourth Theileria sp. shown to be present in Zambia.

Bovine babesiosis (Babesia bovis infection) in Zambia

Two cases of Babesia bovis, a parasite associated with the tick Boophilus microplus, are reported for the first time from the central part of Zambia. It is concluded that infected B. microplus ticks are occasionally introduced into central Zambia by tick-infested cattle from the north-eastern part of the country where B. bovis is endemic. The spread of B. microplus in Southern Africa in a westward direction is discussed and related to the epidemiology of bovine babesiosis in Zambia.

Transmission of a Trypanosoma sp. to cattle by the tick Hyalomma anatolicum anatolicum

Hyalomma anatolicum anatolicum engorged nymphs and flat adults were collected from two areas in northern Sudan. Various developing stages of Trypanosoma theileri-like flagellates were observed in the engorged nymphs, freshly moulted adults and mature adults partially engorged on rabbits. When these ticks were applied to two calves, one calf became infected with the trypanosome. The parasites were observed for one day in the enlarged lymph node nearest to the tick-feeding site 5 days after the tick application. Subsequently the trypanosomes were re-isolated in vitro from the infected calf. Inoculation of a ground-up tick supernatant suspension from the infected batch of ticks containing 10(4) trypanosomes into a calf did not produce a patent infection.

Isolation and transmission of Cowdria ruminantium (causal agent of heartwater disease) in Blue Nile Province, Sudan

Heartwater was diagnosed in sheep at the Umm Banein Livestock Research Station, Blue Nile Province, Sudan. Cowdria ruminantium was isolated from sheep by subinoculation of blood into a goat. Adult Amblyomma lepidum ticks fed as nymphs on this goat transmitted heartwater to a Friesian (Bos taurus) calf. Brain stabilates from this calf, either snap-frozen into liquid nitrogen or frozen slowly in a deepfreezer at -70 degrees C, with DMSO as cryoprotectant, were infective to cattle when inoculated subcutaneously.

Cultivation of Theileria. II. Attempts to cultivate erythrocytic stages of Theileria mutans

Blood from calves with a parasitaemia of Theileria mutans was cultivated in vitro in various ways. No significant increase in the percentage of infected red cells was observed, but the percentage of dividing forms of the parasite rose sharply during the first two days of incubation. The conditions of the cultures were apparently unsuitable for the invasion of erythrocytes.

Cultivation of Theileria. I. Attempts to complete the cycle of Theileria parva in vitro

Microschizonts and free merozoites developed in bovine lymphoblastoid cell cultures containing macroschizonts of 6 different strains of Theileria parva. Clean bovine red cells were added to the cultures, which were incubated in various ways. No penetration of red cells by merozoites was observed, not even when cultures in diffusion chambers were introduced into the peritoneal cavity of non-infected cattle.

Isolation and transmission of Theileria mutans (Chisamba) in Zambia

Theileria mutans (Chisamba) was isolated from a steer at Chisamba, Central Province, Zambia by inoculation of blood into a susceptible unsplenectomised calf. The parasite was then transmitted on three occasions by nymphs and once by adult Amblyomma variegatum ticks. Macroschizonts, typical for T mutans, were detected in two calves for short periods. The parasite caused varying degrees of anaemia in all experimental calves, whose sera showed high antibody titres to T mutans in the indirect fluorescent antibody test.

Infection rates of Theileria annulata in the salivary glands of the tick Hyalomma marginatum rufipes

Theileria annulata was experimentally transmitted to cattle on two occasions by the two-host tick Hyalomma marginatum rufipes. Transmission was transstadial; engorged nymphs fed on Theileria annulata-infected calves transmitted the disease as adults. Salivary glands of all partially fed and incubated adult ticks were heavily infected with Theileria parasites. Immatures attached rapidly and fed successfully on cattle. However, since the immature stages of this species normally feed on birds, this tick is unlikely to be an important vector in the field.

Note on the transmission of Theileria annulata by Hyalomma ticks in the Sudan

Nymphs of Hyalomma impeltatum and H. dromedarii, fed as larvae on an infected calf, transmitted fatal Theileria annulata infection to two susceptible calves. The significance of these findings is discussed in relation to the epidemiology of tropical theileriosis in the Sudan.

Natural infection rates of Hyalomma anatolicum anatolicum with theileria in Sudan

Hyalomma anatolicum anatolicum ticks were collected around cattle pens at two locations close to Khartoum. They were assessed for theileria infection by four methods. Salivary glands were stained whole with methyl green pyronin and examined for parasite masses. Adult ticks were partially fed on rabbits, ground up in medium, and the suspensions were examined in Giemsa stained smears and by inoculation into bovine lymphocyte cultures. Ticks were fully fed on calves which were monitored for developing theileriosis. H a anatolicum were found infected with parasite masses similar to those seen in experimental infections with T annulata. At one site 38 per cent of 102 ticks were infected and the mean number of parasite masses per tick for the whole sample was 37. At the other site 86 per cent of 156 ticks were similarly infected and the mean parasite masses per tick was 19.5. Suspensions of sporozoites contained sporozoites typical of those found in experimental preparations of T annulata. Sporozoites harvested from ticks from both locations infected and transformed normal bovine lymphocyte cultures. H a anatolicum ticks from both locations produced fatal theileria infection in susceptible calves.

The influence of various bovine sera on the maintenance of Theileria parva lymphoblastoid cell culture

Theileria parva infected lymphoblastoid bovine cells were grown in a medium based on HEPES-buffered RPMI 1640 with glutamine and antibiotics, supplemented with bovine serum. There were no significant differences in growth rate, viability, and percentage of infected cells when the substrate contained 10 or 20 per cent of either commercially available newborn calf serum of serum prepared from adult non-infected Friesian cattle or of serum prepared from a Friesian calf immunised against East Coast fever and having a high titre of antibodies to T. parva antigen in the indirect fluorescent antibody test. If studies showing that newborn calf serum gives results in the establishment and maintenance of T. parva cell culture similar to those of foetal calf serum are confirmed, this finding could mean an appreciable saving in the cost of in vitro work on this parasite.

Artificial infection of Rhipicephalus appendiculatus with Theileria parva by percutaneous injection

Rhipicephalus appendiculatus nymphs were inoculated with fresh or cryopreserved blood containing Theileria parva piroplasms, or with cell culture grown stages of T parva. The use of fresh blood was successful. Cryopreserved blood containing dimethylsulphoxide (DMSO), killed most nymphs after inoculation: DMSO could be removed by slow dialysis, without destroying the infectivity of the blood. Attempts to infect ticks by inoculating cell culture grown stages of T parva failed, even when large numbers of merozoites were present in the inoculum.

Cowdria ruminantium (Rickettsiales) in primary goat kidney cell cultures

Fresh or cryopreserved kidney tissue from goats suffering from heart water (Cowdria ruminantium infection) was infective when inoculated intravenously into susceptible goats. Primary kidney cell cultures were established from 14 goats reacting to C ruminantium infection; they were tested for infectivity by intravenous injection into susceptible goats after periods varying from five to 31 days. Three cultures, five, 12 and 13 days old, induced heartwater in recipients. The other 11 cultures, varying in age from six to 31 days, did not cause any reaction and all 11 recipient goats died from heartwater on challenge. C ruminantium could not be detected microscopically in the cell cultures.