Clinical and pathological findings of a newly recognized disease of elephants caused by endotheliotropic herpesviruses

The unique clinical and pathological findings in nine Asian (Elephas maximus) and two African (Loxodonta africana) elephants from North American Zoos with a highly fatal disease caused by novel endotheliotropic herpesviruses are described. Identification of the viruses by molecular techniques and some epidemiological aspects of the disease were previously reported. Consensus primer polymerase chain reaction (PCR) combined with sequencing yielded molecular evidence that confirmed the presence of two novel but related herpesviruses associated with the disease, one in Asian elephants and the second in African elephants. Disease onset was acute, with lethargy, edema of the head and thoracic limbs, oral ulceration and cyanosis of the tongue followed by death of most animals in 1 to 7 days. Pertinent laboratory findings in two of three clinically evaluated animals included lymphocytopenia and thrombocytopenia. Two affected young Asian elephants recovered after a 3 to 4 wk course of therapy with the anti-herpesvirus drug famciclovir. Necropsy findings in the fatal cases included pericardial effusion and extensive petechial hemorrhages in the heart and throughout the peritoneal cavity, hepatomegaly, cyanosis of the tongue, intestinal hemorrhage, and ulceration. Histologically, there were extensive microhemorrhages and edema throughout the myocardium and mild, subacute myocarditis. Similar hemorrhagic lesions with inflammation were evident in the tongue, liver, and large intestine. Lesions in these target organs were accompanied by amphophilic to basophilic intranuclear viral inclusion bodies in capillary endothelial cells. Transmission electron microscopy of the endothelial inclusion bodies revealed 80 to 92 nm diameter viral capsids consistent with herpesvirus morphology. The short course of the herpesvirus infections, with sudden deaths in all but the two surviving elephants, was ascribed to acute cardiac failure attributed to herpesvirus-induced capillary injury with extensive myocardial hemorrhage and edema.

Three new Sarcocystis species, Sarcocystis giraffae, S. klaseriensis, and S. camelopardalis (Protozoa: Sarcocystidae) from the giraffe (Giraffa camelopardalis) in South Africa

Three new Sarcocystis species recovered from muscle fibers of the skeletal musculature of a giraffe in South Africa are described based on light and electron microscopy. Sarcocystis giraffae n. sp. formed slim macrocysts with a parasite-induced connective tissue encapsulation of the host muscle fiber in which the plasma membrane of the latter remained unaltered. The sarcocyst wall represented a new ultrastructural type that is characterized by fingerlike villar protrusions with a hairlike projection at the tip, containing microtubules penetrating the ground substance. Sarcocystis klaseriensis n. sp. formed small filiform microcysts with kinked finger-shaped villar protrusions of the wall, containing scattered microtubules or filaments, and represented another new ultrastructural type. Sarcocystis camelopardalis n. sp. formed small filiform microcysts with straplike villar protrusions of the wall, containing chainlike osmiophilic structures, and represented again a new ultrastructural type.

Sarcocystis dubeyella n. sp. and Sarcocystis phacochoeri n. sp. (Protozoa: Sarcocystidae) from the warthog (Phacochoerus aethiopicus) in South Africa

Sarcocystis dubeyella n. sp. and S. phacochoeri n. sp. from muscle fibers of the skeletal musculature of two warthogs in South Africa are described by light and and electron microscopy. Sarcocystis dubeyella sarcocysts are macroscopic (up to 12 mm long and 1 mm wide), with a parasite-induced encapsulation of the host muscle fiber in which the plasma membrane of the latter remained unaltered. The sarcocyst wall is characterized by evenly arranged, irregularly semicircular or rectangular villar protrusions (5.0 x 2.8-11.0 microns) with indented margins and no specific content. Sarcocystis phacochoeri formed filiform microcysts (up to 4 mm long and 0.13 mm wide). Its cyst wall is provided with tightly packed, molarlike villar protrusions (1.6-3.3 x 1.7-3.3 microns), with smooth margins, hollow on one side, and with longitudinal condensations of the fine granular matrix at various locations in the interior.

The efficacy of an experimental oil-adjuvanted encephalomyocarditis vaccine in elephants, mice and pigs

An oil-adjuvanted inactivated encephalomyocarditis (EMC) vaccine was developed to protect a wild population of elephants against a natural outbreak of disease. The experimental vaccine was initially tested for efficacy by challenging mice and pigs. Mice showed protection against challenge and pigs developed high antibody levels. Since both vaccinated and control pigs failed to develop clinical disease, apparently due to the low virulence of the strain in this species, protection in pigs could not be evaluated. Vaccinated elephants developed high antibody titers which protected all vaccinates from a challenge roughly two months post-vaccination, whereas controls developed fatal or sub-clinical myocarditis. This is the first report of an inactivated EMC vaccine inducing high antibody titers in domestic and wild animal species. Due to the potency of this vaccine and the acceptability of the oil adjuvant used, it has potential for use in animals in zoological collections as well as in the pig industry.

Detection of AHV-1 DNA in lung sections from blue wildebeest (Connochaetes taurinus) calves by in situ hybridization

In situ hybridization was performed on formalin-fixed, paraffin-embedded lung sections from eight blue wildebeest (Connochaetes taurinus) calves to investigate the role of this organ in the excretion of alcelaphine herpes virus-1 (AHV-1). A digoxigenin labelled Smal fragment of AHV-1 was used as a DNA probe. Viral DNA was detected in the lungs of seven calves in which infection with AHV-1 had previously been confirmed, indicating the significance of the lower respiratory tract in viral replication and excretion. The results also confirmed the sensitivity of the in situ hybridization technique in detecting low amounts of viral DNA in infected cells in routinely processed tissues.

Public health risks associated with the utilisation of wildlife products in certain regions of Africa

The authors describe the public health risks associated with wildlife products in certain regions of Africa. Most of the information presented is obtained from the Republic of South Africa, particularly the Kruger National Park. There are no statutory requirements in South Africa regarding the general inspection of game carcasses prior to sale: however, current regulatory inspection requirements are explained. Game farming systems in southern Africa are generally extensive systems with wild herbivores living in a near-natural 'free-ranging' state. Several pathological processes and disease entities have been confirmed in wildlife carcasses and these are listed with zoonotic implications.

Animal health risks associated with the transportation and utilisation of wildlife products

The animal health risks associated with the movement of wildlife products are infinitely less than those associated with the movement of live animals. Very few pathogens are sufficiently robust to survive the significant changes in temperature, pH, moisture content and osmolality which occur post mortem, or which are associated with preservation processes such as pickling, smoking or drying. Certain pathogens, however, (e.g. foot and mouth disease, classical swine fever [hog cholera] and African swine fever viruses and the anthrax bacillus) are hardy and resistant to these environmental changes and therefore constitute a finite animal health risk if raw, undercooked or under-preserved products from infected wild animals are imported. Other less robust pathogens, such as rinderpest virus, may remain infectious in animal products if these are obtained from acutely infected animals and frozen immediately. Macroparasitic diseases such as trichinellosis and echinococcosis-hydatidosis, if present in the unprocessed tissues of infected wildlife, are potentially infectious to carnivorous or omnivorous companion animals. The importation of untreated wet hides may result in the introduction of alien ectoparasites and/or the infectious diseases for which they are vectors. The author discusses the more significant pathogens found in free-ranging wildlife which should be taken into consideration when importing wildlife products from endemically or epidemically infected countries.

Persistent infection of African buffalo (Syncerus caffer) with SAT-type foot-and-mouth disease viruses: rate of fixation of mutations, antigenic change and interspecies transmission

Transmission of a plaque-purified SAT-2 foot-and-mouth disease virus (FMDV) occurred erratically from artificially infected African buffaloes in captivity to susceptible buffaloes and cattle in the same enclosure; in some instances transmission occurred only after contact between persistently infected carriers and susceptible animals lasting a number of months. Because the rate at which FMDV mutations accumulated in persistently infected buffaloes was approximately linear (1.64 percent nucleotide substitutions per year over the region of the 1D gene sequenced), both buffaloes and cattle that became infected some months after the start of the experiment were infected with viruses that differed from the original clone. The nucleotide differences were reflected in significant antigenic change. A SAT-1 FMDV from a separate experiment inadvertently infected some of the buffalo in the SAT-2 experiment. The SAT-1 FMDV also accumulated mutations at a constant rate in individual buffaloes (1.54 percent nucleotide changes per year) but the resultant antigenic variation was less than for SAT-2. It is concluded that persistently infected buffaloes in the wild constantly generate variants of SAT-1 and SAT-2 which explains the wide range of genomic and antigenic variants which occur in SAT-1 and SAT-2 viruses in southern Africa.

The 1992 foot-and-mouth disease epizootic in the Kruger National Park

The monitoring of a foot-and-mouth disease epizootic amongst impala (Aepyceros melampus) in the Kruger National Park is described. Infection rates of different sex and age classes of impala within the outbreak focus were determined. Seroprevalence rates in other clovenhoofed species were also determined. RNA sequencing of a portion of the 1D gene of viruses isolated from SAT-2 viruses obtained from diseased impala showed that they were unrelated to previous SAT-2 isolates made from animals in the Kruger National Park.

An outbreak of bovine tuberculosis in a free-living African buffalo (Syncerus caffer--sparrman) population in the Kruger National Park: a preliminary report

Bovine tuberculosis was diagnosed for the first time in an African buffalo (Syncerus caffer) in the Kruger National Park (KNP). The index case was a 2-year-old, emaciated bull which had been found recumbent and obviously ill, near the south-western boundary of the KNP, in July 1990. During a follow-up random sampling of 57 buffalo, from two herds in close proximity to this initial case, nine more suspect cases were found. Mycobacterium bovis was isolated from a lung and thoracic lymph node, respectively, of two of these cases. Histopathologically, all nine of these animals had granulomatous lesions compatible with a diagnosis of mycobacteriosis, but acid-fast organisms could be demonstrated in only one animal.

Epidemiology of African horsesickness: antibodies in free-living elephants (Loxodonta africans) and their response to experimental infection

The presence of low levels of group- and type-specific antibodies against African horsesickness virus in the serum of some free-living elephants was reconfirmed. Experimental infection resulted in conflicting results. No detectable viraemia nor virus could be demonstrated in the organs of the six elephant calves and none of them mounted significant levels of neutralizing antibodies against the virus. On the other hand, all calves showed a slight rise in ELISA titres. This rise, however, was modest when compared with the rise in experimentally infected zebra. The presence of low levels of group- and type-specific antibodies in the serum of some free-living elephants is judged to be the result of natural hyper-immunization due to frequent exposure to infected biting insects. Elephants should therefore, despite the presence of low levels of antibodies, be regarded as poorly susceptible and unlikely to be a source of African horsesickness virus.

Genome variation in the SAT types of foot-and-mouth disease viruses prevalent in buffalo (Syncerus caffer) in the Kruger National Park and other regions of southern Africa, 1986-93

Dideoxy nucleotide sequencing of a portion of the 1D gene of SAT-type foot-and-mouth disease viruses (FMDV) was used to derive phylogenetic relationships between viruses recovered from the oesophageo-pharyngeal secretions of buffalo in the Kruger National Park as well as several other wildlife areas in southern Africa. The three serotypes differed from one another by more than 40% while intratypic variation did not exceed 29%. Within each type, isolates from particular countries were more closely related to one another than to isolates from other countries lending credence to previous observations that FMDV evolve independently in different regions of the subcontinent.

Advanced tuberculosis in an African buffalo (Syncerus caffer Sparrman)

A necropsy conducted on an emaciated 8-year-old female African buffalo (Syncerus caffer) in the Kruger National Park, revealed gross pathological changes compatible with generalised bovine tuberculosis. Macroscopic lesions in the lungs and associated lymph nodes were of a caseous necrotic nature with liquefied foci. Mycobacterium bovis was cultured from pulmonary lesions. The distribution and the characteristics of the lesions are described and the conclusion is made that the initial route of infection was aerogenous with secondary bacterial metastasis to the intestine. It would also appear that the spread of infection within the animal was extremely rapid. The conjecture is made that due to the cavernous state of the pulmonary lesions, the animal was probably highly infective at the time of death. Environmental factors that may have had an influence on the pathogenesis of the disease are seasonal rainfall fluctuations, extreme temperature variations and harsh ultra-violet exposure.

Maintenance of foot and mouth disease viruses in buffalo (Syncerus caffer Sparrman, 1779) in southern Africa

Using age-related infection rates derived from serological data in available deterministic and specially developed stochastic simulation models, it has been possible to establish that the basic reproductive rates for South African Territory (SAT) type foot and mouth disease virus in buffalo (Syncerus caffer) are high. The models predict that there is a periodicity of infection within herds and possibly the population as a whole. Thus, buffalo herds are likely to be more infectious at some times than at others. However, because most infections in buffalo are inapparent, such episodes are difficult to identify. There is wide intratypic variation within the SAT type virus populations circulating in buffalo. This was determined by sequencing part of the 1 D gene of buffalo isolates and establishing antigenic profiles with neutralising monoclonal antibodies and conventional antisera.

Incidence of feline immunodeficiency virus reactive antibodies in free-ranging lions of the Kruger National Park and the Etosha National Park in southern Africa detected by recombinant FIV p24 antigen

Lion sera from the Kruger National Park (KNP) dating back to 1977 and from the Etosha National Park (ENP), obtained from 1989 to 1991, have been analysed by ELISA and Western blot analyses using a genetically engineered antigen representing the p24 structural protein of feline immunodeficiency virus (FIV). It was concluded that some 83% of 98 KNP lion sera reacted with the p24 antigen, while none of 28 ENP lion sera reacted. A few other KNP felids (cheetahs and genets) gave samples that did not react with the FIV p24 antigen. For the KNP lions, apart from a lower prevalence in cubs (50%), no particular trends were demonstrated in terms of age, sex, date or origins of the samples. In Western blot and radio-immunoprecipitation analyses the lion sera reacted with the engineered p24 antigen, as well as with the p15 and p24 gag proteins and the p50 gag precursor protein from FIV, indicating that the agent is probably a lentivirus related to FIV. The ELISA with the engineered p24 antigen required less serum and appears to be more sensitive at detecting FIV-reactive antibodies than assays with available commercial kits.

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.

Epidemiology of wildebeest-derived malignant catarrhal fever in South Africa: inability to transfer the disease with an African face fly Musca xanthomelas (Diptera: Muscidae)

Under experimental conditions an African face fly (Musca xanthomelas) preferred to feed on cattle dung when provided with a choice of 3 different meals namely sucrose, cattle dung and blood. Flies starved overnight fed well on the eyes of cattle and rabbits, but were reluctant to feed again within 2 h after being allowed to feed on cell culture medium or on the eyes of wildebeest, and when they did feed, they preferred to feed on the external side of the eyelids and on the coagulated material in the medial canthus of the eye. Under field conditions flies were rarely seen to feed on the eyes of immobilized wildebeest. Although M. xanthomelas became infected with Alcelaphinae herpes virus 1 (AHV-1) when they fed on infective wildebeest tears or cell culture medium, they lost the virus within 5 h, and recovery of infective AHV-1 particles from regurgitated cell culture medium was limited to the first 30 min after feeding. AHV-1 could not be transmitted by flies to cattle or rabbits. The failure to transfer the virus with flies can be ascribed to their reluctance to feed on cattle or rabbits shortly after they have consumed a protein rich meal, the rapid inactivation of ingested virus and the relatively high titre of virus necessary to infect cattle via the ocular route. Furthermore, it is believed that under natural conditions flies that have emerged from cattle dung will be inclined to stay with cattle where food is freely available.(ABSTRACT TRUNCATED AT 250 WORDS)

Excretion of alcelaphine herpesvirus-1 by captive and free-living wildebeest (Connochaetes taurinus)

Excretion of alcelaphine herpesvirus-1 (AHV-1) is for all practical purposes limited to wildebeest calves under the age of 4 months. Sixty-one per cent of calves 1-2 months of age excreted virus with a mean titre of 9.8 X 10(4) cytopathic-forming foci/ml in their ocular fluid. The incidence declined sharply to less than 2% in wildebeest older than 6 months. No difference in age-related excretion of virus could be detected between free-living and captive wildebeest and no virus could be isolated from free-living pregnant wildebeest cows or from captive cows and their calves during the first 4 weeks after birth. The occurrence of wildebeest-derived malignant catarrhal fever (WD MCF) during spring, when wildebeest do not excrete virus, is a strong indication of the existence of an alternative host or an intermediate host capable of biological transfer of AHV-1.

Failure of Haematobia thirouxi potans (Bezzi) to transmit foot-and-mouth disease virus mechanically between viraemic and susceptible cattle

In 2 separate experiments the blood-feeding fly Haematobia thirouxi potans (Bezzi) failed to transmit foot-and-mouth disease virus when transferred from viraemic (log 2,6-log 4,3 MLD50 or TCID50/ml) to susceptible cattle. Each experiment involved 2 susceptible and 2 viraemic animals housed in separate stables and 2,000-4,000 flies of which most had fed on viraemic hosts 120 min prior to transfer. Furthermore, only minimal quantities of virus were isolated from free-living flies captured on experimentally infected buffalo (Syncerus caffer) in the acute stages of infection.

Foot-and-mouth disease and the African buffalo (Syncerus caffer). 1. Carriers as a source of infection for cattle

Ten pregnant buffalo cows, six of which were subsequently shown to be carriers of SAT 1, 2 and 3 viruses, were captured in the Kruger National Park (KNP) and allowed to calve in captivity. The buffalo cows and calves were separated by a fence from 6 FMD susceptible cattle but the buffalo and cattle were obliged to use common drinking troughs and hay racks. Over a period of 15 months, during which the buffalo calves lost their maternally-derived immunity, neither the buffalo calves nor the susceptible cattle became infected with FMD virus. By the end of the observation period, however, only 1 buffalo cow still had detectable virus in its oesophageal/pharyngeal specimens.

Foot-and-mouth disease and the African buffalo (Syncerus caffer). II. Virus excretion and transmission during acute infection

Three groups of young buffalo in captivity were infected by exposing them to similar buffalo in the acute stages of infection induced by needle inoculation with SAT 1 or 2 viruses. Clear foot lesions developed in most of the buffalo from which the relevant virus types were re-isolated. During the first week following infection virus was found in blood, nasal secretions, saliva, preputial secretions and faeces. Air samples collected in the immediate vicinity of acutely infected buffalo were also found to contain virus. However, the regularity of virus detection as well as the quantity of virus in buffalo specimens was generally lower than for cattle infected with viruses of the same type. Conversely, virus was detected in the nasal secretions or saliva of 3 buffalo up to 4 weeks after infection, a situation which has not been encountered in cattle. Susceptible cattle and impala (Aepyceros melampus) were penned together with or in the immediate vicinity of infected buffalo and shared feeding and watering facilities with the buffalo. The pattern of transmission which emerged indicated that transfer of these viruses from buffalo to other species probably occurs only in the acute stages of infection and where there is direct physical contact between the species.

Buffalo in the northern Natal game parks show no serological evidence of infection with foot-and-mouth disease virus

A total of 594 sera collected from buffalo (Syncerus caffer) in the Hluhluwe/Umfolozi Game Reserve complex, Ndumu Game Reserve and the eastern shores of Lake St Lucia were examined for antibody to SAT 1, 2 and 3 types of foot-and-mouth disease (FMD) virus in neutralization tests. No neutralization of SAT 2 or 3 viruses was exhibited by any of the sera tested at final dilutions greater than 10. A small proportion (2,9%) of sera neutralized SAT 1 virus at dilutions up to 10, but these were considered to be due to non-specific reactions. This, together with the absence of clinical FMD in both cattle and game in this region over at least a 45-year period and the failure to isolate FMD virus from pharyngeal scrapings of buffalo sampled in the area, leads to the conclusion that FMD does not occur in these buffalo populations.

Baroreceptor reflex in the rat after converting enzyme inhibition or angiotensin receptor blockade

1. One component of baroreflex responsiveness was quantitated in conscious rats using the heart rate response to a pressor injection of phenylephrine. 2. Endogenous angiotensin and its effectiveness were manipulated by sodium deprivation, converting enzyme inhibition and infusion of an angiotensin analogue. None of these manoeuvres changed the observed reflex responsiveness. 3. We conclude that endogenous angiotensin has no influence on the component of baroreceptor function that is described by the slope of the arterial pressure-heart rate relationship.