Feline Leishmaniasis Caused by Leishmania infantum: Parasite Sequencing, Seropositivity, and Clinical Characterization in an Endemic Area From Brazil.

Zoonotic leishmaniasis caused by Leishmania infantum is a disease of One Health concern since human and animal cases and environmental damage are interconnected. L. infantum has a complex epidemiological cycle with multiple hosts, including mammals-humans, domestic, and wild animals-and arthropod vectors. Knowledge on mammal infections in endemic areas is crucial for developing control strategies. This work aimed to detect and characterize L. infantum infection in domestic cats from areas where human and canine leishmaniasis cases occur. No cases of feline leishmaniasis (FeL) had been previously reported in those areas. Five municipalities from Bahia state were chosen, comprising 2,480.8 km2 with 1,103,866 inhabitants. Ninety domiciliated and/or sheltered cats underwent clinical examination and serology by a rapid reference test recommended by the Brazilian government. Cytology, PCR, and parasite DNA sequencing were performed in bone marrow samples. Rapid tests detected antibodies in 5.6% (5/90) of the cats. Leishmania infantum infection was confirmed in 7.8% (7/90) of the cats by PCR, sequencing, and parasite isolation. Three out of the five municipalities (60%) had infected cats, and PCR positivity varied from 6.9 to 29%. One cat was categorized as harboring active L. infantum infection with amastigote forms in bone marrow smears. No clinical signs were detected at the first clinical exam, but 1 month later the cat developed severe FeL. The cat isolate was grown in culture, typed and its DNA sequence was homologous to the L. infantum reference strain (PP75). In conclusion, cats are potential hosts and may acquire L. infantum in endemic areas where canine and human cases occur. For cats, the need for surveillance, differential diagnosis and clinical care is highly recommended since a fast clinical progression of FeL developed in a subclinical animal. An accurate standardized immunodiagnostic assay for FeL is warranted.

Histopathological Parameters of Canine Bone Marrow in Cell-Block Preparations.

Studies using the cell-block technique for bone marrow (BM) analysis are limited in the veterinary literature. This work assessed whether the histopathological analysis of canine BM was feasible using cell-block cytoinclusions prepared from fine-needle sternal aspirate samples. Eight clinically healthy young-to-middle-aged dogs underwent both fine-needle sternal aspiration for BM cell-block (BM-Cb) processing and iliac-crest BM core biopsy (BM-B). Histopathologic parameters were compared between the 2 methods. There were no statistically significant histopathological differences between hematopoietic tissue areas (P = .6294) in the BM-Cb and BM-B sections, and they had similar microscopic characteristics and microarchitecture. Cellularity and reticulin-fiber staining were equivalent in the BM-Cb and BM-B preparations in 87.5% (7/8) and 100% (8/8) of the sections, respectively. However, the quantitative results of the megakaryocytic series differed between BM-Cb and BM-B in 37.5% (3/8) of the sections, and the myeloid:erythroid (M:E) ratios differed between the 2 methods in 25% (2/8). These preliminary data indicate that cell-block preparations made from sternal fine-needle aspiration samples warrant continued evaluation in a larger number of animals, including those with various diseases affecting the bone marrow.

Spatial distribution of canine Leishmania infantum infection in a municipality with endemic human leishmaniasis in Eastern Bahia, Brazil.

Efforts to control a zoonotic disease such as visceral leishmaniasis (VL) caused by Leishmania infantum can be successful if they rely on comprehensive data on animal infection. In Bahia state, Brazil, human VL is endemic, yet some areas have no epidemiological data on canine L. infantum infection and canine leishmaniasis (CanL) to date. We aimed to perform an epidemiological study describing the spatial distribution and characterizing canine L. infantum infection in two districts of the municipality of Muritiba, where human cases have occurred. Brazilian official serodiagnostic protocol (ELISA and immunochromatographic tests), PCR and clinical examination were performed in 351 owned dogs. A seroprevalence of 15.7% (55/351) was found, and L. infantum identified in 88.8% (32/36) of PCR tested samples. Spatial distribution of positive dogs indicated infection in both urban and rural districts. There was no association between seropositivity and sex or breed, but dogs older than 2 years were 3.8 times more likely to be seropositive (95% CI 1.57 - 9.18) than younger dogs. Among seropositive dogs, 80% (44/55) had clinical manifestations of CanL: 75% (33/44) presented dermatopathy, 50% (22/44) emaciation, and 29.5% (13/44) ophthalmopathy. This is the first report on canine seroprevalence and natural L. infantum infection in Muritiba, Bahia.

Histaminergic H1 and H2 receptors located within the ventromedial hypothalamus regulate food and water intake in rats.

The aim of the present study was to investigate the effect of the pharmacological blockade of histamine H1 and H2 receptors located within the ventromedial hypothalamus (VMH) on overnight food and water intake and on water intake elicited by two physiological stimuli: hyperosmolarity induced by an acute intragastric salt load and water deprivation. During the overnight period, the pharmacological blockade of both H1 and H2 VMH receptors significantly increased food intake and decreased water intake. In hyperosmotic rats, the blockade of H1 VMH receptors reduced water intake, while the blockade of H2 receptors in this same region yielded no significant effect. Additionally, in water-deprived rats, the blockade of both H1 and H2 receptors located within the VMH induced a significant decrease in water intake. The inhibitory effects on drinking behavior observed in this study do not seem to be a consequence of any "illness-inducing" effect provoked by the central administration of the antihistaminergic agents employed here, because an aversion test indicated that the injection of those compounds into the VMH does not induce any "illness-like" effect. In addition, the central administration of either mepyramine or cimetidine to dehydrated and hyperosmotic rats did not produce any reduction in locomotor activity measured in an open-field arena. Injections of the antihistaminergic agents used here into the regions that circumscribe the VMH produced no significant effects on water or food intake, indicating that the actions observed here may be specifically attributed to the set of histaminergic receptors situated within the VMH.

Central 5-HT2B/2C and 5-HT3 receptor stimulation decreases salt intake in sodium-depleted rats.

In the present study, we investigated the participation of central 5-HT(2B/2C) and 5-HT(3) receptors in the salt intake induced by sodium depletion in Wistar male rats. Sodium depletion was produced by the administration of furosemide associated with a low salt diet. Third ventricle injections of mCPP, a 5-HT(2B/2C) agonist, at doses of 80, 160 and 240 nmol, promoted a dose-dependent reduction in salt intake in sodium-depleted rats. The inhibitory effect produced by central administration of mCPP was abolished by the central pretreatment with SDZ SER 082, a 5-HT(2B/2C) antagonist. Similar results were obtained with third ventricle injections of m-CPBG (80, 160 and 240 nmol), a selective 5-HT(3) agonist that also induced a dose-related decrease in salt intake in sodium-depleted rats. The central pretreatment with LY-278,584, a selective 5-HT(3) receptor antagonist, was able to impair the salt intake inhibition elicited by third ventricle injections of m-CPBG. Central administration of each one of the antagonists alone or a combination of both antagonists together did not significantly change salt intake after sodium depletion. On the other hand, the central administration of both mCPP and m-CPBG, in the highest dose used to test their effect on salt intake (240 nmol), was unable to modify blood pressure in sodium-depleted rats. It is concluded that: (1) pharmacological activation of central 5-HT(2B/2C) and 5-HT(3) receptors diminishes salt intake during sodium depletion, (2) an inhibitory endogenous drive exerted by central 5-HT(2B/2C) and 5-HT(3) receptors does not seem to exist and (3) the reduction in salt intake generated by the pharmacological activation of these central receptors is not produced by an acute hypertensive response.

Central 5-HT(3) receptors and water intake in rats.

In the present paper, we studied in rats the effect of third ventricle administration of m-chlorophenylbiguanide hydrochloride (1-(3-chlorophenyl)biguanide (m-CPBG), a selective 5-HT(3) agonist, on water intake induced by three different physiological stimuli: water deprivation, acute salt load and hypovolemia. Central acute m-CPBG injections in the doses of 80 and 160 nmol significantly reduced water intake elicited by an acute salt load. Third ventricle injections of m-CPBG in the dose of 160 nmol significantly inhibited water intake in hypovolemic animals, whereas third ventricle injections of m-CPBG in a higher dose (320 nmol) were necessary to decrease water intake in water-deprived rats. Pretreatment with 1-methyl-N-[8-methyl-8-azabicyclo(3.2.1)-oct-3-yl]-1H-indazole-3-carboxamide (LY-278,584), a selective 5-HT(3) antagonist, abolished the inhibitory effect on water intake seen after central administration of m-CPBG in all groups studied. The central administration of m-CPBG was also able to inhibit water intake induced by pharmacological activation of central cholinergic and angiotensinergic pathways. Third ventricle injections of m-CPBG in the highest dose employed in this study (320 nmol) were unable to modify food intake in food-deprived rats. An aversion test has shown that acute third ventricle injections of m-CPBG do not induce illness-like effects that could explain the water intake inhibition here observed. Also, central administration of m-CPBG did not modify the intake of a "dessert" meal consisting of diluted condensed milk. It is concluded that central 5-HT(3) receptor activation exerts a specific inhibitory effect on water intake.