The biochemical, morphological and virulence profiles of Bacillus anthracis isolated in the Kruger National Park

The biochemical, morphological and virulence profiles of 44 Bacillus anthracis isolates, obtained from various localities and carcass remains of wild animals in the Kruger National Park, South Africa, were examined. The morphological characteristics tested for included: the formation of capsules on bicarbonate agar, the motility of the vegetative organism, the presence of haemolysis on blood tryptose agar, the sensitivity of the vegetative organism to bacteriophage, the production of lecithinase on egg yolk agar, the liquefaction (hydrolysis) of gelatine and the capability of each isolate to produce mucoid colonies when grown on bicarbonate agar with horse serum in an atmosphere containing CO2. The API 50CHB and 20E systems were used to evaluate the biochemical activity of each isolate. The virulence of each isolate was determined by its LD50, using an inbred line of Balb/C mice. A clear pattern in the biochemical reactions emerged that appeared to be specific for each isolate. On the API 50CHB test strip, only 2 of the 44 isolates gave a 100% positive reaction to all 10 of the biochemical substances to which it was supposed to react, 9 gave positive results to 90%, 19 were positive to 80%, and 14 were positive to 70%. The reactions on the API 20E were completely different from what was expected, with only 1 of the biochemical activities (gelatinase production) showing a positive reaction to all the isolates. The virulence test indicated that 27/44 isolates could be regarded as highly virulent with a LD50 of less than 1,000 organisms, and the rest of the isolates as virulent with a LD 50 of 1,001-10,000 organisms.(ABSTRACT TRUNCATED AT 250 WORDS)     

Fire behaviour in the Kruger National Park

Abstract

Fire research in the Kruger National Park has largely been focussed on the effect of the season and frequency of burning on the vegetation. Very little information is available on the effect of fire behaviour and in particular fire intensity, on the flora of the Park. Consequently a research project was conducted to develop statistical models for predicting fire intensity, flame height and rate of spread in the field. The devleopment of these models constitutes the initial phase of determining the relationship between fire behaviour and vegetation response.     

The tegument of Schistosoma hippopotami from Hippopotamus amphibius in the Kruger National Park

Schistosoma hippopotami were collected from the right heart chambers and pulmonary arteries of Hippopotamus amphibius culled in the Kruger National Park. The schistosomes were subjected to scanning electron microscopy as well as optical microscopy. The results indicate that S. hippopotami is not conspecific to S. mansoni as suggested in the literature. On account of the morphology of certain tegumental structures of both male and female parasites, it is suggested that S. hippopotami is adapted to the pulmonary arterial circulation of its host.     

The Reproductive Seasons of Some Mammals in the Kruger National Park

During a study on the presence and location of Meloidogyne incognita race 2 within maize roots, a nematode-trapping fungus, Arthrobotrys dactyloides was observed for the first time on maize in South Africa.     

Drag-sampling of free-living ixodid ticks in the Kruger National Park

Free-living ticks were collected by means of drag-sampling in 32 of the 35 landscape zones of the Kruger National Park during a period of 1 calendar month. Of the 18,199 specimens collected, 99.53% were larvae, 0.05% nymphs and 0.42% adults. Fourteen species were collected. Amblyomma hebraeum followed by Boophilus decoloratus, predominated, both in distribution and abundance. Large variations were encountered between drags. There was no correlation between the numbers of larvae collected and time of day, temperature, grass length, vegetation biomass estimates and subzone type.     

Social relationships and dispersal patterns in a clan of spotted hyaenas Crocuta crocuta in the Kruger National Park

Membership, social relationships and dispersal were recorded for all members of one clan of spotted hyaenas, Crocuta crocuta, in the Kruger National Park over a period of 27 months. The clan comprised females, cubs, and three social classes of males: resident natal males, peripheral immigrant males and central immigrant males. Although a linear dominance hierarchy was recorded under all circumstances, it was most strongly expressed at food. Females were philopatric and maintained a network of amicable relationships with each other and their offspring. Social dominance assured them priority of access to carcasses, so that they obtained a high proportion of meat. Males left their natal clans and attempted to join neighbouring clans, where they were initially treated as territorial intruders, but could eventually gain membership albeit with low social status, lowest feeding priority at carcasses and precarious social relationships. An immigrant male that maintained close attendance on females became a central immigrant and gained unrivalled breeding status. The segregation of a clan into co-operative relatives and subordinate immigrants assures an optimal distribution of resources.     

Cowdria ruminantium infection in ticks in the Kruger National Park.

Adult Amblyomma hebraeum ticks, the principle vector of heartwater (cowdriosis) of domestic ruminants in southern Africa, were collected in pheromone traps placed in Kruger National Park, an exclusively wildlife sanctuary in South Africa. These ticks transmitted Cowdria ruminantium, the rickettsial agent causing heartwater, to a susceptible goat, resulting in acute, fatal disease. C ruminantium was isolated in bovine endothelial cell culture from the plasma of this animal during the febrile stage of the disease and transmitted to susceptible goats, causing fatal heartwater. The prevalence of C ruminantium infection in 292 ticks was determined by polymerase chain reaction (PCR) analysis to be 1.7 per cent (95 per cent confidence interval 0.71 to 4.0 per cent). A DNA probe analysis, which is less sensitive than PCR, detected infection in three of the five PCR-positive ticks. The remaining infections were below the detection limit of the DNA probe, which is approximately 70,000 organisms. This is the first evidence that a vector-wildlife cycle of transmission of C ruminantium can be maintained independently of domestic ruminants.     

Bone-collecting habits of spotted hyaenas Crocuta crocuta in the Kruger National Park

An examination of 18 Crocuta crocuta dens in the Kruger National Park, showed that this species can be responsible for bone assemblages at dens, more so at permanent sites such as granite or calcrete caves than at temporarily occupied aardvark holes or road culverts. Because of the facultative nature of food-transporting behaviour, the rate at which bones are accumulated at dens varies, ranging from no bones collected to nine food items collected per month. The relative abundance of ungulate species represented in the large assemblages resembles that of ungulates living in the region surrounding a den.     

Serological reactions to Leptospira species in buffalo (Syncerus caffer) from the Kruger National Park

Four hundred and six serum samples from buffalo (Syncerus caffer) were tested for leptospirosis, using the microscopic agglutination test. Seven buffaloes (1.7%) reacted positive and 27 (6.6%) inconclusive. Reactions against L. tarassovi and L. hardjo were the most prevalent.     

Tuberculosis in kudus (Tragelaphus strepsiceros) in the Kruger National Park.

Five kudus (Tragelaphus strepsiceros), three bulls and two cows, within the Greater Kruger National Park complex, were diagnosed with generalized tuberculosis caused by Mycobacterium bovis. The lesions seen in these animals were similar to those previously reported in kudus and included severe tuberculous lymphadenitis of the nodes of the head and neck (that resulted in noticeable uni- or bilateral swelling beneath the ear), thorax, and the mesentery. All the animals also suffered from severe granulomatous pneumonia. The lesions in the lungs were more severe cranially and had a miliary distribution elsewhere in the lungs. Based on the DNA patterns of the M. bovis isolates, at least some of these kudus were infected with strains commonly present in tuberculous buffaloes, lions, cheetahs, and baboons in the Park whereas other strains from these kudus were quite different and may reflect another source of infection. The presence of tuberculous kudus in the Park is expected to complicate control measures that may be instituted to contain or eradicate the disease in the Park.     

Mitochondrial DNA sequence variation in Hippopotamus amphibius from Kruger National Park,Republic of South Africa

Populations of Hippopotamus amphibius have declined throughout Africa in recent years, and are expected to decline further. An understanding of the population genetics of individual populations of hippos is necessary for effective management. To that end, we sequenced a portion of the mitochondrial DNA (mtDNA) control region or D-loop from 37 H. amphibius, from six herds in the central region of Kruger National Park (KNP), Republic of South Africa. We amplified a 453 bp segment by PCR, and identified 21 polymorphic sites and seven haplotypes. All of these haplotypes are private alleles, not found in other populations of hippos from southern Africa. Overall nucleotide diversity (π) was 0.01739, and haplotype diversity (hd) was 0.8273, within the range observed in other parts of Africa. Mismatch analysis conformed more closely to a model of constant population size than either rapid demographic or spatial expansion. An analysis of molecular variance demonstrated no significant differentiation among herds, and Mantel tests showed no significant relationship between geographic and genetic distance among herds separated by up to 47 km (measured as Euclidean [x,y] distance) or 77 km (measured along rivers). Over this range, the population appears to be a single panmictic unit. A test of the hypothesis that calves are more likely to share a mtDNA haplotype with an adult female in the same herd than an adult female from a different herd was not significant.     

Copper poisoning in the Kruger National Park: field investigation in wild ruminants

Chronic copper poisoning was investigated in ruminants within the Phalaborwa area of the Kruger National Park (KNP). Exposure of ruminants to environmental copper pollution resulting form copper smelting operations of a mine in the area was examined by comparing impala faecal copper concentrations in dung heaps and tissue (liver, lung and kidney) copper concentrations of organs collected from impala and buffalo culled within three risk zones (high, moderate and low) of the study area in relation to the distance from the smelter over a period of 4 years. An additional area within the KNP not exposed to the environmental copper pollution from the mine served as control. Tissue copper accumulation was also determined in tracer impala placed in the highest risk zone. The results of this study confirmed the occurrence of chronic copper poisoning in impala and indicated an inverse relationship in extent of impala faecal copper elimination and in tissue copper accumulation in impala and buffalo with distance from the copper smelter. Impala liver copper concentrations were shown to be a reliable indicator of copper accumulation for these ruminants. The presence lung copper concentrations, indicating the exposure to airborne copper were the highest in impala culled in the zone closest to the smelter. Liver copper concentrations above the diagnostic limit of 150 ppm for chronic copper poisoning in domestic sheep were consistently found in impala within the highest risk zone. Clinical pathological measurements suggested that AST activity could possibly be used as an indicator for chronic copper poisoning in impala. It is concluded that, in addition to the environmental and geo-botanical evidence previously reported, the copper smelter of a nearby copper mine is the most likely source of copper pollution responsible for chronic copper poisoning in impala and the occurrence of high copper concentrations in buffalo in the Phalaborwa area of the KNP.     

The prevalence of blood parasites in helmeted guineafowls, Numida meleagris, in the Kruger National Park

Bloodsmears were taken from separate groups of five helmeted guineafowls, Numida meleagris, shot at approximately monthly intervals at Skukuza and near Lower Sabie in the Kruger National Park during the period August 1988 to August 1990. Ninety-eight (86%) of 114 guineafowls had single or multiple infections of Aegyptianella sp., Haemoproteus pratasi, Hepatozoon sp., Leucocytozoon neavei, Plasmodium circumflexum and Trypanosoma numidae. The apparent seasonal prevalence of Aegyptianella sp., H. pratasi and L. neavei, the three most commonly occurring parasites (42%, 49% and 56% of birds infected respectively), is probably dependent on the presence of their respective vectors.     

The rise and fall of tuberculosis in a free-ranging chacma baboon troop in the Kruger National Park

A single troop of free-ranging chacma baboons (Papio ursinus) was found to be infected with tuberculosis caused by Mycobacterium bovis. It is assumed that some members of the troop originally became infected when feeding on a tuberculous carcass in the veld or on tuberculous material scavenged at a nearby post mortem facility. Subsequently, apparent aerosol transmission took place while sleeping in an unused room. Oral transmission probably also occurred due to continuous contamination of the floor of this room and the common, narrow access (a train bridge crossing the Sabi River) to it with faeces and urine. A macroscopic prevalence of 50 % was found and the disease was noted to progress rapidly in infected baboons. A variety of organs had typical tuberculous lesions, of which the spleen, lungs and mesenteric lymph nodes were consistently, grossly affected. Using Restriction Fragment Length Polymorphism analysis, all but one of the baboon isolates were found to be identical to the most common African buffalo (Syncerus caffer) isolate (genotype 1) in this Park. The opportunistic sleeping facility was made inaccessible to the troop, which was forced to revert to sleeping in trees. A follow-up survey six months after closure, demonstrated that the disease had disappeared from the troop, and that no spillover infection had occurred into neighbouring troops.     

Estimating grass fuel loads with a disc pasture meter in the Kruger National Park

Abstract

The major portion of the fuel load in the savanna areas comprises surface fuels in the form of the standing grass sward. The disc pasture meter was successfully calibrated for estimating grass fuel loads in the main landscapes of the Kruger National Park. The calibration comprised estimating the mean disc height of a 4 m² quadrat and harvesting the grass as close to ground level as possible. Using a large quadrat gave highly satisfactory results indicating that this procedure should be considered as a standard method of calibration, particularly in grass swards having a low basal cover.