An indirect enzyme-linked immunosorbent assay for diagnosis of American canine hepatozoonosis

Neuroprotective effects of zafirlukast, piracetam and their combination on L-Methionine-induced vascular dementia in rats

Vascular dementia is considered a vascular cognitive impairment disease caused by neuronal degeneration in the brain. Several studies have supported the hypothesis that oxidative stress and endothelial dysfunction are the main pathogenic factors in vascular dementia. This current study aims to determine the possible neuroprotective effects of zafirlukast, piracetam and the combination of piracetam and zafirlukast on L-methionine-induced vascular dementia in rats. Male Wistar albino rats were divided into five groups. Group I was the normal control, and group II received L-methionine (1700 mg/kg, P.O.) for 32 days. The remaining groups received zafirlukast (20 mg/kg, P.O.), piracetam (600 mg/kg, P.O.) or their combination (zafirlukast 20 mg/kg + piracetam 600 mg/kg, P.O.) for 32 days after L-methionine administration. Afterwards, the cognitive and memory performances of the rats were investigated using the novel object recognition (NOR) test; rats were then sacrificed for histopathological and biochemical analyses. L-methionine-induced vascular dementia altered rats' behaviours and the brain contents of different neurotransmitters and acetylcholinesterase activity while increasing levels of oxidative stress and causing notable histopathological alterations in brain tissues. The treatment of vascular dementia with zafirlukast and the combination improved neurochemical, behavioural and histological alterations to a comparable level to those of piracetam. Thus, zafirlukast, piracetam and the combination of both drugs can be considered as potential therapeutic strategies for the treatment of vascular dementia induced by L-methionine. To the best of our knowledge, this study is the first to explore the neuroprotective effects of zafirlukast and piracetam on L-methionine-induced vascular dementia.

Neuroprotective Effects of Simvastatin and Cilostazol in L-Methionine-Induced Vascular Dementia in Rats

Vascular dementia (VaD) is a degenerative cerebrovascular disorder that leads to progressive decline in cognitive abilities and memory. Several reports demonstrated that oxidative stress and endothelial dysfunction are principal pathogenic factors in VaD. The present study was constructed to determine the possible neuroprotective effects of simvastatin in comparison with cilostazol in VaD induced by L-methionine in rats. Male Wistar rats were divided into four groups. Group I (control group), group II received L-methionine (1.7 g/kg, p.o.) for 32 days. The remaining two groups received simvastatin (50 mg/kg, p.o.) and cilostazol (100 mg/kg, p.o.), respectively, for 32 days after induction of VaD by L-methionine. Subsequently, rats were tested for cognitive performance using Morris water maze test then sacrificed for biochemical and histopathological assays. L-methionine induced VaD reflected by alterations in rats' behavior as well as the estimated neurotransmitters, acetylcholinesterase activity as well as increased brain oxidative stress and inflammation parallel to histopathological changes in brain tissue. Treatment of rats with simvastatin ameliorated L-methionine-induced behavioral, neurochemical, and histological changes in a manner comparable to cilostazol. Simvastatin may be regarded as a potential therapeutic strategy for the treatment of VaD. To the best of our knowledge, this is the first study to reveal the neuroprotective effects of simvastatin or cilostazol in L-methionine-induced VaD. Graphical Abstract ᅟ.

Prevalence and diversity of Hepatozoon canis in naturally infected dogs in Japanese islands and peninsulas

Canine hepatozoonosis is a worldwide protozoal disease caused by Hepatozoon canis and Hepatozoon americanum and is transmitted by ixodid ticks, Rhipicephalus and Amblyomma spp., respectively. H. canis infection is widespread in Africa, Europe, South America, and Asia, including Japan. The objective of this study was to study the distribution pattern and diversity of H. canis in naturally infected dogs in nine Japanese islands and peninsulas. Therefore, 196 hunting dogs were randomly sampled during the period from March to September 2011 and the ages and sexes were identified. Direct microscopy using Giemsa-stained blood smears revealed H. canis gametocytes in the peripheral blood of 45 (23.6%) dogs. Polymerase chain reaction (PCR) was performed on EDTA-anticoagulated blood, initially with the common primer set (B18S-F and B18S-R) amplifying the 1,665-bp portion of the 18S rRNA gene, and then with the specific primer set (HepF and HepR) amplifying about 660 bp fragments of the same gene. Based on PCR, 84 (42.9%) dogs were positive using the common primer and 81 (41.3%) were positive using the specific primer. The current investigation indicated that all screened areas, except for Sado Island and Atsumi Peninsula, were infected. Yaku Island had the highest infection rate (84.6% in males and 100.0% in females), while Ishigaki Island showed the lowest infection rates (8.3% in males and 17.7% in females). Both sexes were infected with no significant difference. However, diversity of infection among the surveyed islands and peninsulas was significantly different (P < 0.05). Although H. canis has previously been reported in dogs in Japan, the higher infection rate described in the current study and the diversity of infection in a wide range of islands strongly encourage prospective studies dealing with the prevention and treatment of the infection in dogs, as well as control of ticks.

Cutaneous Hepatozoon canis infection in a dog from New Jersey

A 7-month-old mixed-breed intact female dog was presented to a private veterinarian with a 2 cm in diameter raised, pruritic, alopecic, subcutaneous, fluctuant swelling over the right eye. Cytology of the mass revealed many degenerate neutrophils, moderate numbers of eosinophils, moderate numbers of macrophages, rare mast cells, and few erythrocytes. Rare neutrophils contained a protozoal agent compatible with a Hepatozoon gamont. Real-time polymerase chain reaction of peripheral blood was positive for Hepatozoon canis. The complete sequence identity of the amplified 18S ribosomal RNA fragment from the dog's blood confirmed H. canis and proved it was relatively distant from the corresponding fragment sequence of Hepatozoon americanum. This case is important in documenting an unusual presentation of infection with H. canis outside of the southern United States.

Perspectives on canine and feline hepatozoonosis

Two species of Hepatozoon are currently known to infect dogs and cause distinct diseases. Hepatozoon canis prevalent in Africa, Asia, southern Europe, South America and recently shown to be present also in the USA causes infection mainly of hemolymphoid organs, whereas Hepatozoon americanum prevalent in the southeastern USA causes myositis and severe lameness. H. americanum is transmitted by ingestion of the Gulf Coast tick Amblyomma maculatum and also by predation on infected prey. H. canis is transmitted by Rhipicephalus sanguineus, in South America also by Amblyomma ovale, and has also been shown to be transmitted transplacentally. Hepatozoonosis of domestic cats has been described mostly from the same areas where canine infection is present and the exact identity of the species which infect cats, their pathogenicity and vectors have not been elucidated. The diagnosis of hepatozoonosis is made by observation of gamonts in blood smears, histopathology, PCR or serology. The main treatment for H. canis is with imidocarb dipropionate whereas H. americanum infection is treated with an initial combination of trimethoprim-sulfadiazine, pyrimethamine and clindamycin followed by maintenance with decoquinate. Treatment for both diseases has not been reported to facilitate complete parasite elimination and new effective drugs are needed for the management of these infections. Prevention of hepatozoonosis should be based on avoidance of oral ingestion of infected tick vectors and infected prey.

Infectious hepatopathies in dogs and cats

This article serves to review the various infectious diseases that affect the liver primarily or as a part of systemic infection. Although bacterial infections are probably the most common cause of infectious hepatitis, the clinician should be aware of other potential organisms and other commonly involved systems. Therefore, this article includes a description of common bacterial, mycobacterial, viral, fungal, protozoal, parasitic, and rickettsial diseases in dogs and cats.

An enzyme-linked immunosorbent assay for antibodies to Hepatozoon canis

Canine hepatozoonosis is a tick-borne protozoal disease caused in the Old World and South America by Hepatozoon canis. An enzyme-linked immunosorbent assay (ELISA) using purified H. canis gamont antigen was applied for the detection of antibodies reactive with H. canis. Evaluation of the ELISA with sera from naturally infected parasitemic dogs indicated that it was sensitive (86%), specific (97%), and comparable to the indirect fluorescent antibody test (IFAT) for the detection of H. canis antibodies. A variable degree of serologic cross-reactivity was found between sera from H. americanum-infected dogs and the H. canis antigen. Dogs experimentally infected with H. canis seroconverted 1-4 weeks post-infection (PI). Antibody levels peaked at 7-9 weeks PI and gradually declined thereafter remaining above the cut-off value until the conclusion of the study 7 months PI. The ELISA will be valuable for serological evaluation of dogs suspected of exposure to H. canis and for epidemiological studies.

American canine hepatozoonosis

American canine hepatozoonosis (ACH) is a tick-borne disease that is spreading in the southeastern and south-central United States. Characterized by marked leukocytosis and periosteal bone proliferation, ACH is very debilitating and often fatal. Dogs acquire infection by ingesting nymphal or adult Gulf Coast ticks (Amblyomma maculatum) that, in a previous life stage, ingested the parasite in a blood meal taken from some vertebrate intermediate host. ACH is caused by the apicomplexan Hepatozoon americanum and has been differentiated from Old World canine hepatozoonosis caused by H. canis. Unlike H. canis, which is transmitted by the ubiquitous brown dog tick (Rhipicephalus sanguineus), H. americanum is essentially an accidental parasite of dogs, for which Gulf Coast ticks are not favored hosts. The geographic portrait of the disease parallels the known distribution of the Gulf Coast tick, which has expanded in recent years. Thus, the endemic cycle of H. americanum involves A. maculatum as definitive host and some vertebrate intermediate host(s) yet to be identified. Although coyotes (Canis latrans) are known to be infected, it is not known how important this host is in maintaining the endemic cycle. This review covers the biology of the parasite and of the tick that transmits it and contrasts ACH with classical canine hepatozoonosis. Clinical aspects of the disease are discussed, including diagnosis and treatment, and puzzling epidemiologic issues are examined. Brief consideration is given to the potential for ACH to be used as a model for study of angiogenesis and of hypertrophic osteoarthropathy.

American canine hepatozoonosis

Hepatozoon americanum infection is an emerging tickborne disease in the southern United States. This organism causes a very different and much more severe disease than does Hepatozoon canis, the etiologic agent of canine hepatozoonosis in the rest of the world. H americanum is transmitted through ingestion of the definitive host, Amblyomma maculatum (the Gulf Coast tick). Clinical signs of American canine hepatozoonosis tend to wax and wane over time and may include lameness, weakness, pain, muscle atrophy, fever, and mucopurulent ocular discharge. Radiographs typically reveal periosteal proliferation of various bones. Extreme leukocytosis is the most common laboratory finding, along with a mild elevation of serum alkaline phosphatase. Diagnosis is made by visualization of gamont-containing neutrophils or monocytes on examination of blood smears; observation of typical cysts, meronts or pyogranulomas on muscle biopsy; or detection of serum antibodies against H americanum sporozoites. Common complications of chronic infection include glomerulopathies, amyloidosis, and vasculitis. Although the prognosis for this disease in the past was guarded to poor, recent advances in treatment have increased the long-term survival rate of infected dogs.

American canine hepatozoonosis

American canine hepatozoonosis is an emerging, tick-transmitted infection of domestic dogs caused by a recently recognized species of apicomplexan parasite, Hepatozoon americanum. The known definitive host of the protozoan is the Gulf Coast tick, Amblyomma maculatum. Presently recognized intermediate hosts include the domestic dog and the coyote, Canis latrans. Laboratory-reared larval or nymphal A. maculatum can be infected readily by feeding to repletion on a parasitemic intermediate host; sporogony requires 35-40 days. Transmission of infection to the dog has been produced experimentally by oral administration of mature oocysts or oocyst-containing ticks. Canine disease follows experimental exposure in 4-6 weeks and is characterized by systemic illness, extreme neutrophilic leukocytosis, muscle and bone pain, and proliferation of periosteal bone. Histopathological findings include multifocal skeletal and cardiac myositis associated with escape of mature merozoites from within the host-cell environment. There is also rapid onset of periosteal activation and osteogenesis and, less frequently, glomerulopathy and amyloidosis. Sequential stages of development of H. americanum in both the dog and the tick have been elucidated. Gamonts potentially infectious to ticks have been observed in peripheral blood leukocytes of the dog in as few as 28 days after exposure to oocysts. Young coyotes experimentally exposed to a canine strain of H. americanum acquired disease indistinguishable from that of similarly exposed young dogs.

Persistence of Hepatozoon americanum (Apicomplexa: Adeleorina) in a naturally infected dog

To determine the persistence of Hepatozoon americanum in a naturally infected dog, skeletal muscle biopsies were performed at approximately 6-mo intervals over a period of 5.5 yr, and the samples were examined for presence of lesions of American canine hepatozoonosis (ACH). Nymphal Amblyomma maculatum (Gulf Coast tick) were allowed to feed to repletion on the dog periodically over the 5.5-yr period, and adult ticks were dissected and examined for presence of H. americanum oocysts. With 3 exceptions, the biopsied muscle contained lesions characteristic of ACH; no evidence of infection was found at 36, 54, and 67 mo after the original diagnosis. In every instance, nymphal Gulf Coast ticks became infected, indicating that dogs naturally infected with H. americanum can remain infectious for Gulf Coast ticks for at least 5.5 yr. Skeletal muscle biopsy is a reasonably reliable method of determining whether dogs are infected with the parasite. Xenodiagnosis using nymphal Gulf Coast ticks is an even more sensitive method, but the procedure is practicable only experimentally. Design of prevention and control measures for ACH must take into account knowledge that the parasite can survive in dogs, and presumably other vertebrate host(s), for long periods. Preventing ingestion of Gulf Coast ticks is an effective control measure.

Larval Gulf Coast ticks (Amblyomma maculatum) [Acari: Ixodidae] as host for Hepatozoon americanum [Apicomplexa: Adeleorina]

Laboratory-reared larval Gulf Coast ticks (GCTs) (Amblyomma maculatum) were exposed experimentally and found to acquire Hepatozoon americanum infection while feeding on parasitemic dogs. These ticks supported gamogonic and sporogonic development of the apicomplexan, and oocysts from newly molted nymphs were infectious for a dog. Other nymphs from this cohort that were allowed to feed on a blood-parasite naive sheep molted normally; the resulting adult ticks contained oocysts that were infectious for another dog. Merogonic development of H. americanum in the dogs and the resulting lesions/disease appeared similar, irrespective of whether infectious oocysts were derived from nymphal or adult ticks that acquired infection as larvae. In the system previously known, nymphal ticks acquire infection and adults harbor infective oocysts, which vertebrate hosts ingest. Given that larval A. maculatum can acquire infection and nymphs can harbor viable oocysts as demonstrated by this study, the potential variety of vertebrate hosts that can alternate with GCTs in maintaining an endemic cycle is considerably expanded.

Comparison of tissue stages of Hepatozoon americanum in the dog using immunohistochemical and routine histologic methods

American canine hepatozoonosis is caused by Hepatozoon americanum, a recently described species of apicomplexan protozoan parasite. An immunohistochemical procedure using a polyclonal antibody to sporozoites of H. americanum clearly identified asexual stages of H. americanum in canine striated muscle. The method also detects hepatozoa present in naturally infected coyotes and raccoons and reacts with certain other apicomplexans. Use of this immunohistochemical procedure confirms the canine intermediate host-parasite relationships that were presumptively established using conventional histopathologic methods.