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J Van Heerden

Publications and source records attributed to J Van Heerden.

At least 19 recordsLinked to original sources
PubMed2006

Prevalence of vaccine-derived polioviruses in stools of immunodeficient children in South Africa.

AIMS: The aim of the study was to determine the prevalence of vaccine-derived polioviruses (VDPVs) in stool specimens of immunodeficient patients such as HIV-positive children (including those with an AIDS indicator condition, according to the Centres for Disease Control and Prevention classification) by applying various molecular techniques. METHODS AND RESULTS: A total of 164 stool samples from HIV-positive children and 23 stool samples from healthy immunocompetent children (the control group) were analysed during 2003 and 2004. By applying a reverse transcription polymerase chain reaction (RT-PCR) in combination with a nested PCR, a total of 54 enteroviruses were detected in the stool specimens of the immunodeficient children. The use of restriction enzymes and a Sabin specific RT-triplex PCR confirmed the presence of 13 polioviruses (PVs), such as seven Sabin PV type 1, four Sabin PV type 3 and two Sabin PV type 2 isolates. The 5'untranslated region and the VP1 capsid-encoding protein of the 13 PVs and the three PVs from the stools of the immunocompetent children were partially sequenced and their genetic relatedness was deduced from the constructed phylogenetic trees. The majority of the PVs isolated from the stools of the immunodeficient children (10 of 13 isolates) were classified as 'oral poliovirus vaccine (OPV)-like viruses', as these isolates had close sequence relationships (>99% in VP1 nucleotide sequences) to the original Sabin PV vaccine strains. Three PVs showed < or =99% VP1 sequence identity to the Sabin PV vaccine strains and were classified as 'suspected' immunodeficient VDPVs (iVDPVs). All of the OPV-like isolates and the 'suspected' iVDPVs carried mutations at specific positions in their partially sequenced regions, which have been associated with reversion of the attenuated Sabin PV vaccine strains to increased neurovirulence. CONCLUSIONS: Thus, this study adds further evidence to the observation that immunodeficient individuals may excrete OPV strains with potential neurovirulent phenotypes. SIGNIFICANCE AND IMPACT OF THE STUDY: Prolonged excretion of PVs by immunodeficient individuals is of major concern, because continued replication of PVs in the human gut could result in the reversion of these viruses to greater neurovirulence. When exposed to OPV, immunodeficient patients may become chronically infected, spreading potentially neurovirulent VDPVs for many months or years to close contacts and children who are no longer being vaccinated after termination of OPV vaccination in the near future.

5' Untranslated Regions↗
PubMed2005

Prevalence of vaccine-derived polioviruses in sewage and river water in South Africa.

Polioviruses (PVs) are not associated with waterborne transmission to the same extent as many other enteric viruses. However, they are typically transmitted by the faecal-oral route, which implies that the risk of infection by exposure to the viruses in water cannot be underestimated. The risk appears particularly high for rural communities, which use sewage-polluted river water for domestic purposes. Thus, the presence in the environment of highly evolved, neurovirulent vaccine-derived poliovirus (VDPV) strains in the absence of polio cases would have important implications for strategies to terminate immunisation with oral poliovirus vaccine (OPV) following global polio eradication. The aim of the current study was to determine the prevalence of VDPVs in selected sewage and river water samples collected from 2001 to 2003, and to construct phylogenetic trees of the partially sequenced 5'untranslated region (5'UTR) and the VP1 region of the genomes to deduce the genetic relatedness between the PV strains. Using the monolayer plaque assay, 703 plaques from sewage and 157 plaques from river water samples were analysed. Application of a RT-multiplex PCR revealed that 176 of these plaques were non-polio enteroviruses, and 49 were PV isolates. The Sabin-specific RT-triplex PCR revealed the presence of 29 Sabin PV type 1, 8 Sabin PV type 2 and 12 Sabin PV type 3 isolates. The 5'UTR and the VP1 region of 13 PV type 1, 7 PV type 3 and 6 PV type 2 isolates were partially sequenced. The majority of the OPV isolates (24 out of 26) displayed close sequence relationships (>99% VP1 sequence identity) to the parental Sabin PV vaccine strains and were classified as "OPV-like viruses". Two isolates (D1 08/28 and OF1 05/21) were found to be highly divergent and were classified as "suspected" VDPVs. Isolate OF1 05/21 (a "suspected" VDPV type 1) showed more than 0.9% divergence in VP1, whereas isolate D1 08/28 (a "suspected" VDPV type 2) showed 1.4% divergence in VP1 from the parental Sabin PV vaccine strains. As with most of the other OPV-like isolates, these "suspected" VDPVs were carrying mutations, which have previously been associated with reversion of the attenuated Sabin PV strains to increased neurovirulence. It was estimated that the total period of replication for the two "suspected" VDPVs was between 12 and 16 months. In conclusion, this study provided new and relevant information on the prevalence of "suspected" VDPVs in sewage and river water, and opened the way to assess the possible broader significance of the findings reported here.

Base Sequence↗
PubMed1997

Aspects of rabies epidemiology in Tsumkwe District, Namibia.

Aspects of rabies epidemiology were investigated in the Tsumkwe District, Namibia, during December 1993 and January 1994. A cross-sectional seroepidemiological survey for rabies antibodies was carried out in domestic (n = 70) and wild dogs [Lycaon pictus (n = 6)]. An overall seroprevalence rate of 30% was found in domestic dogs, but it must be borne in mind that seroconversion can result from infections from either rabies or rabies-related viruses. Older dogs were more likely to be seropositive and there was spatial and temporal clustering of seropositivity. No wild dogs were found seropositive. A demographic survey of the domestic-dog population in the area showed that the total dog-population size was 132, or 0.027 dogs per km2. The dog population consisted mainly of young dogs with a median age of 1.5 years, and had a female bias of 0.63 males per female. Questionnaire surveys suggested that spotted hyaenas (Crocuta crocuta) and black-backed jackals (Canis mesomelas) were the most common larger carnivores found in and around villages, and that dogs were kept mainly for guarding.

Animals↗
PubMed1997

Seroepidemiological survey of sympatric domestic and wild dogs (Lycaon pictus) in Tsumkwe District, north-eastern Namibia.

Disease is a potential threat to many endangered populations and may originate from sympatric domestic species. This paper describes a cross-sectional serological survey of canine pathogens carried out in domestic (n = 70) and wild dogs (Lycoan pictus) (n = 6), in Tsumkwe District, northeastern Namibia. Evidence of past exposure to canine distemper virus, canine adenovirus and parainfluenza virus was evident in both wild and domestic dogs with this, the first, documented exposure of free-living wild dogs to canine distemper. Domestic dogs were also exposed to rabies virus, canine parvovirus and coronavirus. There was no pathogen to which wild dogs, but not domestic dogs, were exposed. With wild dogs known to be susceptible to rabies and canine distemper, these may be the greatest threat to this population of wild dogs, although some wild dogs can clearly survive infection with canine distemper.

Adenoviruses, Canine↗
PubMed1995

An investigation into the health status and diseases of wild dogs (Lycaon pictus) in the Kruger National Park.

Many factors have been cited as possible reasons for the decline in the number of wild dogs (Lycaon pictus), but few studies have provided supportive data. Between 1990 and 1993, the dynamics of 10 wild dog packs in the southern district of the Kruger National Park in South Africa were monitored. Casual observations of the causes of disease and mortality in the entire population were also recorded. During the same period, 46 wild dogs were immobilised, weighed, and subjected to physical examination as well as the collection of blood and faecal specimens. External parasites were collected and blood smears were prepared. Serum specimens were subjected to routine blood chemistry analyses, hormone and serological assays and formalinised blood specimens and faeces were subjected to screening for endoparasites. The study population varied from 75 in 1990 to 123 in 1993 with a survival rate of 29.9% for pups, 64.3% for yearlings and 69% for adults. Eighty per cent or more of the population were under 4 years of age. The cause of death in all wild dogs in the Kruger National Park could be established only in a small number of cases. Lions were responsible for the death of 20/62 wild dogs and disease caused the death of 6/62 wild dogs. All immobilised dogs were in a good physical condition, but 85% of dogs had one or more skin lesions. Potential life-threatening lesions (bitewounds inflicted by other dogs and lesions inflicted by a snare) occurred in 4 dogs. One male dog had only one testicle in the scortum. Twenty-six (93%) blood smears were positive for gametocytes of Hepatozoon sp., presumably H. canis, and in 2 dogs trophozoites of Babesia canis were seen. Eighty-six per cent of the specimens were positive for Dipetalonema reconditum. All dogs were infested with ticks and Haemaphysalis leachi, Amblyomma hebraeum, A. marmoreum, Boophilus decoloratus, Rhipicephalus simus, R. evertsi, R. appendiculatus and R. zambesiensis were identified. Ctenocephalides sp. and Echidnophaga larina were also identified. Taenia sp., Toxascaris canis and Ancylostoma caninum were present in faecal specimens. Antibody titres to adenovirus (26/31), B. canis (6/15), canine para-influenza virus (21/31), coronavirus (20/31), Coxiella burnetti (8/29), reovirus Type 3 (9/31), Rickettsia conori/africae (27/29), rotavirus (16/31) and Toxoplasma gondii (16/16) were found. The average serum urea concentration was higher (16.4 mmol/e) than that described for captive wild dogs, but other biochemical parameters were generally in agreement with values reported for captive wild dogs.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1994

Aortic thrombosis in a dog with glomerulonephritis.

A Bearded Collie was presented with clinical signs of intermittent weakness, intermittent pain in the back legs and a bilateral absence of the femoral pulse. Further diagnostic investigations revealed proteinuria, hypoproteinaemia, hyperlipidaemia and azotaemia. A quantitative estimation of the proteinuria using a protein/creatinine ratio indicated a loss of 483 mg kg-1 of protein per day. A large caudal aortic thrombosis was demonstrated by means of non-selective angiography and ultrasonographic examination. Autopsy confirmed an extensive aortic thrombus extending from the level of the fourth lumbar vertebra to include both iliac and femoral arteries at the level of the stifle joints. A large thrombus, 4 cm in length, was also found in the pulmonary artery. Histopathological examination of the kidneys revealed a subacute to chronic membranoproliferative glomerulonephritis.

Animals↗
PubMed1994

The wild dog (Lycaon pictus): a new host for Ancylostoma caninum.

Faecal nematode egg counts performed on one captive and 49 free-ranging wild dogs (Lycaon pictus) revealed the presence of eggs of Ancylostoma spp. in 12 (24%) of the animals. The captive wild dog pup showed anorexia, general malaise, pale mucous membranes and black stools. Adult male and female Ancylostoma caninum were recovered from an approximately 3-month-old pup which died of distemper-like disease and a 9-year-old severely debilitated captive wild dog. A single adult A. caninum was also recovered from the intestines of a free-ranging wild dog in the Kruger National Park. These findings confirm the wild dog to be a host for A. caninum.

Ancylostoma↗
PubMed1994

Serological relationship between a donkey alphaherpesvirus (isolate M7/91) and equid herpesvirus type 1 and 4.

Rabbit hyperimmune serum prepared against a donkey alphaherpesvirus isolate (M7/91), and against EHV-1 and EHV-4 was used to characterise the antigenic relationship between these 3 viruses. Serum from immunised rabbits was always more specific for homologous virus and showed different cross reactivity for heterologous virus. It was concluded that the immunologic relationship between the M7/91 isolate and EHV-1, was closer than that between this isolate and EHV-4. A serological survey of donkeys (n = 116) and horses (n = 57) revealed evidence of the presence of neutralising antibody to M7/91 in their sera. The titres of antibody to M7/91 in donkeys, ranged from 1:32-1 > or = 256 and was significantly higher than antibody titres to EHV-1 and EHV-4, while in horses, titres were lower but comparable to equine herpesvirus 1 and 4.

Alphaherpesvirinae↗
PubMed1992

Hypodipsic hypernatraemia in a miniature schnauzer.

Normovolaemic hypernatraemia as a result of a suspected congenital primary hypodipsia was diagnosed in a young male Miniature Schnauzer. Despite an elevated serum sodium concentration, the dog did not appear dehydrated on physical examination and the urine osmolality: plasma osmolality ratio was greater than 4; antidiuretic hormone deficiency was therefore not suspected. Basal serum cortisol and thyroxine concentrations were normal. Plasma aldosterone concentration and plasma renin activity (37 pmol l-1 and 1.55 ng dl-1 h-1 respectively) were within normal range. A defective central thirst regulation mechanism was suspected as the dog was totally disinterested in drinking water despite the chronically elevated serum sodium concentration. Excessive ingestion of water mixed with food, and milk resulted in hyponatraemia and associated cerebral oedema. On stabilisation of the dog's condition, a calculated fluid intake based on daily maintenance fluid requirements was prescribed to prevent recurrence of hypernatraemia and hyponatraemia, and associated signs of central nervous system disease. The dog was in apparent good health with controlled fluid intake when examined 230 d later.

Animals↗
PubMed1991

Immobilization of wild dogs (Lycaon pictus) with a tiletamine hydrochloride/zolazepam hydrochloride combination and subsequent evaluation of selected blood chemistry parameters.

A tiletamine hydrochloride/zolazepam hydrochloride combination was used successfully to immobilize captive untamed wild dogs (Lycaon pictus) (n = 16) at dosage rates ranging from 2.3 to 32.3 mg/kg. Animals remained immobilized for periods ranging from 35 min to 24 hr 14 min. There was a significant positive correlation (r = 0.85, P less than 0.01) between dosage rate and the time immobilized. Profuse salivation and intermittent mild myoclonal contractions were observed in some wild dogs. Mildly reduced partial oxygen and carbon dioxide pressures as well as reduced concentrations of bicarbonate were observed in arterial blood at 10 and 20 min after administration of the drug. Serum concentrations of sodium, potassium, chloride, phosphorus, calcium, magnesium, urea, creatinine, glucose, proteins, albumin, gammaglutamyltransferase, creatinine kinase, aspartate transaminase, alkaline phosphatase, lactate dehydrogenase, insulin, cortisol and thyroxine are presented. These concentrations were found to be in agreement with values previously reported for wild dogs.

Animals↗
PubMed1990

Selected laboratory parameters of thoroughbreds.

Selected haematological, blood chemical and serological variables were investigated in healthy Thoroughbreds (n = 45) in training. Haemoglobin concentration, haematocrit, red, white and differential cell counts as well as serum concentrations of total and ionized calcium, sodium, potassium, chloride, urea, creatinine, total protein, albumin, inorganic phosphorus, total bilirubin, iron, glucose, magnesium, alkaline phosphatase, gamma-glutamyltransferase, lactate dehydrogenase, aspartate transaminase, alanine transaminase and creatine kinase were found to be within ranges previously reported for horses. No statistically significant difference was found between the haematocrit (Ht) of horses n = 44; mean = 0.44; SD = 0.02) of different performance or between those of different age groups. A significant difference was found between the Ht of males (mean = 0.43; SD = 0.02) and females (mean = 0.45; SD = 0.02) and between quiet (mean = 0.44; SD = 0.02) and excitable (mean = 0.46; SD = 0.02) horses. No significant difference in red cell potassium concentration was found between horses of different performance. Cortisol, insulin, parathormone (C-terminal), aldosterone and folate concentrations respectively varied between 89-204 (mean = 144.4; SD = 25.47) nmol l-1, 4.2-23 (mean = 10; SD = 4.30) m U l-1, 65.2-91.4 (mean = 79.46; SD = 9.34) pmol l-1, less than 138 to 379 pmol l-1 and 9.4-21.5 (mean 14.5; SD = 2.87) nmol l-1. Vit B12 concentrations exceeded 1400 pmol l-1. Blood lead concentrations in all animals were below 15 ug l-1. Fifteen (33.3%) of the horses were carriers of babesiosis. Laboratory findings concerning these horses did not differ from those of the other horses.

Animals↗
PubMed1990

Polycythaemia vera in a dog.

An 8-month-old Dachshund showed signs of severe depression and intermittent, mild generalised seizures. A diagnosis of polycythaemia vera was made and the clinical signs ascribed to the hyperviscosity associated with this condition. Treatment by phlebotomy was initiated before the dog died.

Animals↗
PubMed1989

Distemper-like disease and encephalitozoonosis in wild dogs (Lycaon pictus).

Clinical signs of a fatal disease resembling those of canine distemper were observed in two groups of captive wild dog (Lycaon pictus) pups 13 days after vaccination with a commercially available combination vaccine for dogs which contained a live attenuated strain of canine distemper virus. Histopathological examination of tissues revealed the presence of intranuclear inclusion bodies in neurons and lesions resembling canine distemper as well as colonies of an Encephalitozoon sp. in the central nervous system and kidneys. Lesions were observed in both organs which resembled those described in other species infected with Encephalitozoon cuniculi.

Animals↗
PubMed1989

An expansile secondary hypophyseal mastocytoma in a dog.

A 5-year-old mixed breed dog was presented with a history of depression and anorexia. Physical examination revealed a pharyngeal tumour and a neurological examination indicated the presence of a possible space-occupying lesion in the brain. Investigative procedures included a bloodsmear, impression smears and cytology of the pharyngeal tumour, haematology, chemical pathology, faecal analysis, urinalysis, electrocardiography, cerebrospinal fluid analysis, hormone assays and a computerised axial tomography scan. Results of these investigations revealed a round cell tumour in the pharynx, hypergammaglobulinaemia (34 g l-1), azotaemia (urea 8.6 mmol l-1 and creatinine 170 mumol l-1), hypoalbuminaemia (20 g l-1), proteinuria, sinus bradycardia (heart rate 60 beats per min), increased concentration of protein in the CSF (1.1 g l-1), hypoadrenocorticism (base line cortisol less than 55 nmol l-1) and hypothyroidism (T4 less than 13 nmol l-1). The computerised axial tomography scan revealed a brain tumour in the region of the hypophysis. The dog was euthanased and a post mortem examination confirmed the presence of a pharyngeal tumour with apparent direct extension of the tumour into the brain. Both tumours were confirmed histologically as mastocytomas.

Animals↗
PubMed1989

Narcolepsy in a long-haired dachshund.

Narcolepsy was diagnosed in a three-month old, longhaired Dachshund presented with a history of sudden onset of episodes of complete collapse. Littermates or immediate ancestors were not affected. Numerous daily cataplectic attacks as well as excessive sleepiness were the main clinical features. The dog did not respond to treatment with methylphenidate and imipramine. The clinical signs of the disease disappeared after treatment with dexamphetamine. This report describes a case presentation, findings of cerebrospinal fluid assay for catecholamines after various treatment regimens and the response of the patient to treatment.

Animals↗
PubMed1988

Isolation of pure Babesia equi and Babesia caballi organisms in splenectomized horses from endemic areas in South Africa.

Both Babesia equi and Babesia caballi are endemic in large parts of South Africa. Attempts were made to obtain pure local isolates of both B. equi and B. caballi for the purpose of developing serological tests to study the epidemiology of equine babesiosis in this country. The indirect fluorescent antibody test was used to screen horses for B. equi and B. caballi in an endemic area. Seven horses and 3 donkeys between 3 and 36 months of age that tested negative were subsequently splenectomized. The splenectomy operation was performed through the abdominal approach. A 100% survival rate was achieved through this method, probably because it reduced the risk involved in the operation. Blood collected from naturally infected horses and passaged in fully susceptible splenectomized horses and a donkey, under laboratory conditions, produced 2 isolates of Babesia caballi and 1 of B. equi. Microscopical and serological examinations confirmed that these were pure isolates.

Animals↗
PubMed1987

Noncirrhotic portal hypertension due to lymphoma. Reversal following splenectomy.

We report a case of bleeding esophageal varices associated with lymphoma. Splenectomy alone reversed the patient's portal hypertension as assessed hemodynamically and clinically. Mechanisms leading to portal hypertension in the setting of splenomegaly from hematologic disorders are discussed. An approach to operative management of these patients, based on preoperative hemodynamic measurements, is suggested for future consideration.

Aged↗