PubMed Health⌕ Search

Biomedical subjects

B L Penzhorn

Publications and source records attributed to B L Penzhorn.

At least 19 recordsLinked to original sources
PubMed2006

Occurrence of Babesia felis and Babesia leo in various wild felid species and domestic cats in Southern Africa, based on reverse line blot analysis.

Reverse line blot (RLB) is a hybridization assay that can be used to detect various blood parasites and differentiate between them. Results, using the RLB, showed that Babesia felis and Babesia leo occurred as single or mixed infections in various felid species, but most frequently in domestic cats and lions, respectively. Prevalence of infection in free-ranging cheetahs in Namibia was low (7, 5%), whereas 50% of free-ranging lions in South Africa and Swaziland were infected. A large number (52, 9%) of samples tested positive only for Babesia, neither B. felis nor B. leo. This could be an indication of at least one further, as yet undescribed, Babesia species in felids.

Acinonyx↗
PubMed2006

Erythrocyte morphology and haemoglobin types of neonatal roan antelopes (Hippotragus equinus) with hypochromic poikilocytic anaemia.

Neonatal, poikilocytic anaemia in some members of the Hippotragini has previously been documented but not fully investigated. This study was undertaken to describe the erythrocyte morphology of roan antelopes (Hippotragus equinus) during the first 4 weeks after birth and to identify aspects of haemoglobin (Hb) production that might be implicated in this syndrome. Twenty-nine roan antelope calves were sampled on, or close to, 1, 7, 14 and 28 days after birth. Erythrocyte morphology was characterized, and microhaematocrit values and Hb parameters determined, for each sampling occasion. Findings indicated a significant change in erythrocyte morphology during the neonatal period and two haemoglobin types, fetal and adult, were identified. The perinatal onset of adult Hb synthesis was delayed relative to the termination of fetal Hb production, resulting in the observed anaemia. Haemoglobin concentration and erythrocyte morphology were significantly correlated. These findings suggest an intimate relationship between Hb synthesis and the observed poikilocytosis. An imbalance in the synthesis of the alpha- and beta-globin chains of Hb (a thalassaemia) may prove to be the underlying pathophysiology of this syndrome.

Anemia, Hemolytic, Congenital↗
PubMed2006

Babesia conradae, sp. Nov., a small canine Babesia identified in California.

Small piroplasms as a cause of canine babesiosis have usually been identified as Babesia gibsoni. Recent genetic studies suggested that small piroplasms are more likely comprised of at least three genotypically distinct species. In southern California, canine babesiosis caused by a small piroplasm has been documented since 1990. Morphological characteristics of this parasite include a small (0.3-3.0 microm) intraerythrocytic merozoite stage with predominantly ring, piriform, tetrad, amoeboid, or anaplasmoid forms. Transmission electron microscopic images of merozoites demonstrate the presence of an apical complex consisting of an inner subplasmalemmal membrane and rhoptries. Based on phylogenetic analyses of the 18S rRNA and the ITS-2 genes, the Californian small piroplasm isolate is more closely related to piroplasm isolates from wildlife and humans in the western United States than it is to B. gibsoni. Molecular and morphologic evidence supports naming the small piroplasm from southern California as a distinct species, Babesia conradae.

Animals↗
PubMed2006

Seroprevalence of Babesia bovis and Babesia bigemina in cattle in the Soutpansberg region, Limpopo Province, South Africa, associated with changes in vector-tick populations.

A survey was conducted at 30 communal dip tanks and on 5 commercial farms in Limpopo Province, South Africa, during 1999 and 2000 to determine the seroprevalence of antibodies to Babesia bovis and Babesia bigemina. Cattle seropositive for B. bovis were found in 97% of the herds on communal land; the overall seroprevalence changed little between 1999 (63.3%) and 2000 (62.4%). All herds surveyed were infected with B. bigemina, and overall seroprevalence decreased significantly from 56.1% in 1999 to 49.3% in 2000. In herds on communal land in Sour Lowveld Bushveld, overall seroprevalence of B. bovis increased from 70% in 1999 to 80% in 2000, while seroprevalence of B. bigemina decreased from 70% in 1999 to 30% in 2000. This was possibly due to an influx of Rhipicephalus (Boophilus) microplus that occurred at the time. In commercially farmed herds the seroprevalence to B. bovis increased significantly from 19% in 1999 to 57.5% in 2000. All commercial herds in the survey tested positive to B. bigemina, with a seroprevalence of 48.3% in 1999 and 47.5% in 2000. During 1999, cattle in 60% of the dip tank/farm herds with only R. (B.) microplus present were approaching endemic stability to both B. bovis and B. bigemina. In 2000, 60% of the herds with only R. (B.) microplus present were approaching endemic stability for B. bovis, while only 45% were approaching endemic stability for B. bigemina. Those dip tanks/farms where only R. (B.) microplus was recorded had a significantly higher seroprevalence of B. bovis than those where both tick species were present.

Animals↗
PubMed2005

Tick, fly, and mosquito control--lessons from the past, solutions for the future.

In order to continue to produce livestock in a sustainable fashion, it is suggested that what was used in the past will continue to form the mainstay of future control. For the foreseeable future, we must conserve what we have, and use it in combination with all the principles of integrated pest management, namely strategic and focussed treatments of animals, environmental control of breeding sites, disease management (including the principles of enzootic stability), and resistant breeds. Whilst new technologies, such as the development of vaccines both against the insect pest in some cases or the disease they transmit in others, and genetic engineering hold out some hope for the future; these are not sufficiently well advanced to permit wholesale application.

Animals↗
PubMed2005

Molecular characterization of Theileria species associated with mortality in four species of African antelopes.

Pathogen DNA was isolated from roan antelope (Hippotragus equinus), sable antelope (Hippotragus niger), greater kudu (Tragelaphus strepsiceros), and common gray duiker (Sylvicapra grimmia) in South Africa whose deaths were attributed to either theileriosis or cytauxzoonosis. We developed Theileria species-specific probes used in combination with reverse line blot hybridization assays and identified three different species of Theileria in four African antelope species. The close phylogenetic relationship between members of the genera Theileria and Cytauxzoon, similarities in the morphologies of developmental stages, and confusion in the literature regarding theileriosis or cytauxzoonosis are discussed.

Animals↗
PubMed2005

The susceptibility of Trypanosoma congolense isolated in Zambézia Province, Mozambique, to isometamidium chloride, diminazene aceturate and homidium chloride.

Resistance to trypanocidal drugs has been detected in various African countries and is a serious impediment to the control of livestock trypanosomosis. To determine whether drug resistant trypanosome strains are present in the Zambézia Province of Mozambique a study was initiated. To assess the effect of the farming system and the drug-use regimen on the development of drug resistance, trypanosome isolates were collected from cattle from subsistence and commercial livestock production systems. The susceptibility of seven isolates against isometamidium chloride, diminazene aceturate and homidium chloride was tested in mice using a multiple-dose test. In four of the seven isolates high levels of drug resistance to diminazene aceturate and isometamidium chloride were detected. In most cases the observed levels of drug resistance correlated with the drug-use practices in the particular livestock production system.

Animals↗
PubMed2004

Confirmation of occurrence of Babesia canis vogeli in domestic dogs in South Africa.

The prevalence of Babesia infections in domestic dogs in South Africa was studied using reverse line blot hybridization and 18S sequence analysis. Babesia canis vogeli was confirmed for the first time in domestic dogs in South Africa. Out of a total of 297 blood samples collected from domestic dogs in Bloemfontein, East London, Johannesburg, Durban and from the Onderstepoort Veterinary Academic Hospital, 31 were positive for Babesia canis rossi, whereas B. c. vogeli was detected in 13 dogs. None of the dogs carried both parasites. The detection of B. c. vogeli has implications with regard to prevalence and varied clinical manifestation of canine babesiosis in South Africa.

Animals↗
PubMed2004

Displacement of Boophilus decoloratus by Boophilus microplus in the Soutpansberg region, Limpopo Province, South Africa.

Boophilus ticks (n = 25,987) were collected from cattle at 30 communal dip tanks and five commercial farms in the Soutpansberg region, Limpopo Province, South Africa, between May 1999 and December 2001. Only 6.6% were Boophilus decoloratus, while 93.4% were Boophilus microplus, a tick that had not been reported from this area previously. B. microplus was the most common Boophilus tick on communal dip tank cattle, while B. decoloratus was more commonly found on commercial farms. Where the two species occurred together, B. microplus tended to displace B. decoloratus. The displacement was almost complete at the communal dip tanks, while on the commercial farms the population change was still in progress at the end of the survey. The present study demonstrated that a postulated reproductive interference was insufficient in preventing B. microplus from spreading when the climatic conditions were favourable to this species, as the displacement in most of the areas appeared to be rapid and complete.

Animals↗
PubMed2004

Progression towards endemic stability to bovine babesiosis in cattle introduced onto a game ranch.

An opportunity to study progression toward endemic stability to Babesia bigemina arose when cattle were reintroduced onto a game ranch in 1999 after an absence of three years. The study was conducted between August 2000 and June 2001. The unvaccinated breeding cows were sampled only once. Calves born during October 1999 were initially vaccinated against B. bigemina and Babesia bovis at the age of 4 months and were then bled at 10, 17 and 20 months of age. Calves born during 2000 were bled at 7 and 8 months of age. Sera were collected from all the cattle sampled and later tested for antibodies against B. bigemina and B. bovis using the indirect fluorescent antibody (IFA) test. Although endemic stability to B. bigemina had not been achieved at Nooitgedacht 2 years after resumption of cattle ranching, the high seroprevalence in the unvaccinated 8-month-old calves suggested that the situation was approaching stability and that calf vaccination against bovine babesiosis was not required. Tick control should therefore be restricted to prevent excessive tick worry. Only vaccinated cattle were positive to B. bovis and it was concluded that the parasite was absent from the ranch.

Animals↗
PubMed2003

Attainment of endemic stability to Babesia bigemina in cattle on a South African ranch where non-intensive tick control was applied.

The seroprevalence of Babesia bigemina and Babesia bovis antibodies in non-vaccinated cattle was monitored on a South African ranch. The main objective was to assess the endemic stability to bovine babesiosis in cattle maintained under relaxed tick-control measures. Cattle were bled at the age of 7, 8, 10, 17, 20 and 30-120 months and the sera tested for the presence of antibodies using the indirect fluorescent antibody (IFA) test. None of the animals were positive to B. bovis. Seroprevalence of B. bigemina antibodies was 46, 70, 90, 92, 54 and 82% in the various age classes, respectively. Endemic stability was therefore reached by the time the calves were 9 months old. The high seroprevalence of B. bigemina was probably due to the high vector tick population on the ranch, which would have encouraged frequent transmission of B. bigemina. An endemically stable situation to B. bigemina could therefore be achieved merely by adopting a tick-control method that allows a reasonable number of ticks on cattle rather than relying entirely on intensive tick control and vaccination.

Animals↗
PubMed2002

Occurrence and diversity of bovine coccidia at three localities in South Africa.

Information on the occurrence and diversity of coccidia infecting cattle in different farming systems in South Africa is lacking. The objective of the study was to determine the levels of infection of coccidia in cattle at three localities and to determine the Eimeria species occurring at each locality. Faecal samples (n=1936) were collected over a 13-month period from a dairy farm (Mallesons), a Bonsmara breeding farm (Kaalplaas) and a Nguni stud farm (Pienaars River). Samples were collected from adults >24 months old and calves <12 months old. The modified McMaster technique was used to determine OPG (oocysts per gram) of faeces. Samples with OPGs > or =2000 were allowed to sporulate in potassium dichromate solution at room temperature. Species identification was done by measurement and morphological characteristic of each species. At Mallesons, 29% of samples were positive, at Kaalplaas 50% and at Pienaars River 52%. The most prevalent species were Eimeria zuernii and E. ellipsoidalis at Mallesons, E. zuernii and E. bovis at Kaalplaas and E. bovis and E. zuernii at Pienaars River, respectively. Adults had very low OPGs. There was a pattern at the three localities in that high OPGs were only recorded in calves, which were also shedding the most pathogenic species.

Age Factors↗
PubMed2001

Babesia leo n. sp. from lions in the Kruger National Park, South Africa, and its relation to other small piroplasms.

Babesia leo, a small piroplasm isolated from lions in South Africa is described as a distinct species based on a phylogenetic analysis of the 18S rRNA gene. Intraerythrocytic trophozoite and merozoite stages of B. leo are morphologically indistinguishable from other small piroplasms of felids. Previous studies showed that B. leo was biologically and antigenically distinct from B. felis, which is known to infect wild and domestic felids in South Africa. Molecular characterization showed strong support for the phylogenetic seperation of B. leo as a distinct species from B. felis and other felid piroplasms. Phylogenetic analysis also showed that Babesia microti and all of the felid piroplasms from Africa with known 18S rRNA gene sequences available, including B. leo, formed a single, separate clade, sister to the other babesial and theilerial piroplasm parasites.

Animals↗
PubMed2001

Feline babesiosis: signalment, clinical pathology and concurrent infections.

Fifty-six cats with naturally occurring Babesia felis infection were studied. No breed or sex predilection could be identified, but there was an apparent predilection for young adult cats less than 3 years of age. Macrocytic, hypochromic, regenerative anaemia was present in 57% of the cats and in-saline agglutination tests were positive in 16%. No characteristic changes were observed in total or differential leukocyte counts. Thrombocyte counts were variable and thrombocytopaenia was an inconsistent finding. Hepatic cytosol enzyme activity and total bilirubin concentrations were elevated in the majority of cats. Serum protein values were mostly normal, but increased values were occasionally observed and polyclonal gammopathies were observed in all cats with increased total globulin concentrations. No remarkable changes in renal parameters were observed. A variety of electrolyte abnormalities occurred in a number of cats, but no consistent pattern of change could be identified. A close correlation was evident between peripheral and central parasite counts. Concurrent infections with Haemobartonella felis, feline immunodeficiency virus and/or feline leukemia virus were identified in a number of cats.

Age Distribution↗
PubMed2000

Coccidian oocyst and nematode egg counts of free-ranging African buffalo (Syncerus caffer) in the Kruger National Park, South Africa.

Faecal specimens collected in the Kruger National Park from 103 African buffaloes (Syncerus caffer) up to 1 year old and 283 buffaloes older than 1 year were examined for the presence of coccidian oocysts and nematode eggs. Most specimens from animals older than 1 year had negative coccidian oocyst counts. Positive specimens from younger animals had significantly higher coccidian oocyst counts than those from older animals. No such difference was found for nematode egg counts.

Age Factors↗
PubMed1999

Occurrence and diversity of coccidia in indigenous, Saanen and crossbred goats in South Africa.

Occurrence and diversity of Eimeria species in two groups of indigenous South African goats kept under traditional management systems, as well as in a mixed herd of Saanen, indigenous and crossbred goats kept under an intensive management system were examined. Infection rates ranged from 88.7 to 100% in the various groups. Mean OPG of immature goats (< 1 year old) exceeded that of adult goats at all three sites. There was no consistent difference between adult OPG counts at the three sites. Under the intensive system, adult crossbred goats had significantly higher OPG counts than adult Saanen or indigenous goats. Overall, OPG counts of immature goats were significantly higher during the dry season (winter) than during the wet season (summer). Ten Eimeria species were identified, Eimeria arloingi being the most prevalent species at all three sites, followed by Eimeria hirci. Up to seven Eimeria species were recovered from individual specimens.

Animal Husbandry↗