Canine leishmaniasis in three foci in Western Sicily

Epidemiology of canine leishmaniosis in Catalonia (Spain) the example of the Priorat focus

An epidemiological survey of canine leishmaniosis was conducted in the Priorat, a rural region in the Northeast of Spain, for 10 years (1985-1994). Seroprevalence throughout the region, determined by dot-ELISA and IFI, was 10.2% (8-12%). Forty percent of the dogs studied had a low level of anti-Leishmania antibodies, whereas only 50% were seronegative. Only one-third of the seropositive dogs had evident symptoms of the disease. Annual incidence of the disease was 5.7% and the level of endemicity was stable during the study. Four Leishmania zymodemes (MON-1, MON-29, MON-77, MON-105) were present in the focus, and their distribution in the different hosts is discussed. Apart from dogs and foxes, no other reservoir host has been found in the region.

Epidemiological patterns of canine leishmaniasis [correction of leishmaniosis] in Western Liguria (Italy)

An epidemiological survey was carried out on the distribution of canine leishmaniasis in Western Liguria (Northern Italy). Blood sera from 21146 dogs collected from 1990 to 1996 were subjected to the indirect immunofluorescence test (IFAT). From 1990 to 1994 (16690 dogs), only monthly seroprevalences were calculated (min 14%-max 60.5%). Dog sera sampled from October 1994 to May 1996 (4456 dogs) were divided into two subgroups (I: October 1994-May 1995; II: October 1995-May 1996). Seroprevalence was 30.3% and 22.1% in these two groups, respectively. Data analysis by log-linear models revealed that serological positivity to Leishmania sp. was significantly associated with a dog's outdoor lifestyle, with a rural environment and with the male sex. Of the 218 dogs which were tested twice seroconversion rates were also higher in outdoor, rural and male dogs while negativization rates were lower in the same groups. Basic reproductive numbers (R0) were 1.53 (subgroup I) and 1.28 (subgroup II).

Protection of dogs from bites of phlebotomine sandflies by deltamethrin collars for control of canine leishmaniasis

Dog collars made of PVC plastic impregnated with the pyrethroid insecticide deltamethrin at 40 mg/g were investigated for their protective efficacy against phlebotomine sandflies. Collared dogs were kept separately (two untreated control dogs lived together) in outdoor enclosures, each with a kennel, in the Cévennes, southern France. To measure sandfly mortality and anti-feeding effects due to the deltamethrin-impregnated collars worn continuously by the dogs for up to 8 months, each dog was periodically sedated and exposed for 2h to 150-200 laboratory-reared Phlebotomus perniciosus females (plus c. 25 males) inside a net (1.2 m square, 1.8 m high) indoors. After dogs were removed from the nets, allowed to recover and returned to their kennels, any dead sandflies were collected from inside the net and counted. Surviving flies were kept overnight, then scored according to whether they were still alive or dead, unfed or blood-fed. From tests 2, 3, 4, 13, 20, 26 and 34 weeks after the dogs began wearing collars, the overall numbers of blood-fed female sandflies recaptured were 75 from two dogs with collars, compared with 1911 from two collarless dogs. Thus, for every 100 flies which fed on collarless dogs, only 4 fed on collared dogs, i.e. the collars protected dogs from 96% of the bites and this activity was maintained for up to 34 weeks. During the same period, the percentage of recaptured female sandflies that had fed on collared dogs was 0-12% compared to 55-95% on collarless dogs. Immediately after dogs were taken out of the nets, 21-60% of flies confined with the collared dogs were found dead, compared to 0-12% with the controls. It is concluded that, at least in the Mediterranean subregion, this insecticidal collar would protect a dog from the majority of sandfly bites and retain a killing effect for a complete sandfly season. Moreover, it seems likely that the use of collars on all dogs in a focus of Leishmania infantum would reduce contact between sandfly vectors and canine reservoir hosts sufficiently to diminish the risk of infection for humans as well as dogs.

The role of dogs in the epidemiology of human visceral leishmaniasis in northern Pakistan

Infantile visceral leishmaniasis (VL) was first reported from north Pakistan over 3 decades age in the remote valleys of the western Himalayas. These foci were reported as being completely devoid of domestic dogs. The later emergence of sporadic cases of infantile VL in the sub-Himalayan region of the country, where dogs are abundant, enabled us to investigate the prevalence of canine disease and study its relation with disease in humans. A serological survey in dogs by direct agglutination test (DAT) and enzyme-linked immunosorbent assay (ELISA) indicated that 18% (DAT) and 26.6% (ELISA) harboured anti-Leishmania antibodies, with older dogs showing higher prevalence; 10% of the infected dogs had no clinical signs of leishmaniasis. Deoxyribonucleic acid (DNA) probing by 32P-labelled Lmet 2 cDNA probe showed high sensitivity with aspirates obtained from the popliteal lymph nodes of dogs but not with skin snips. Parasites isolated from dogs in these foci were identified as L. infantum by isoenzyme characterization.

Canine leishmaniasis in the Gargano promontory (Apulia, South Italy)

We examined 444 dogs by visiting farms and peripheral districts on the Gargano promontory (Province of Foggia, Apulia, South Italy). Clinical examination and immunofluorescence antibody test for leishmaniasis were performed. Bone marrow and lymph node samples obtained from 25 dogs with positive serological test were cultured on Tobie-Evans medium. The results obtained show both a higher seropositivity rate for canine leishmaniasis (14.4%) and a higher percentage of asymptomatic dogs with positive serological test (53.1%) compared to previous research in the same area. Seven strains isolated from infected dogs belonged to Leishmania infantum species zymodeme Montpellier 1. None of 82 sera of humans living in close contact with infected dogs were positive for leishmaniasis.

Evora district as a new focus for canine leishmaniasis in Portugal

On the basis of information acquired from local health authorities in Evora district of Portugal on cases of visceral leishmaniasis (VL), an epidemiology survey study was conducted. To determine the prevalence of anti-Leishmania antibodies in the local human and canine populations residing in Evora town and 14 adjacent villages, blood samples collected from 885 children and 3,614 dogs were tested in a direct agglutination test (DAT). Seropositivity for Leishmania parasite obtained by DAT in both endemic populations was further confirmed by an enzyme-linked immunosorbent assay (ELISA) and immunofluorescence test (IFAT). For identification of the responsible sandfly vector, 79 biotopes within the study areas were surveyed. In the infantile population assessed, none of the children screened showed an antibody level indicative (titer, > = 1:3200) of visceral leishmaniasis in the DAT. However, agglutinating antibody rates ranging from 0.7% to 6.9% were obtained in dogs residing in Evora and 11 adjacent villages. Concordant seropositivity of 94.04% was obtained by ELISA and IFAT in the same canine population (141) identified by DAT. Of the 159 sandflies captured, 67 were identified as Phlebotomus sergenti; 15, as P. ariasi; 58, as P. perniciosus; and 19, as Sergentomyia minuta. Unlike the results previously reported in Alto-Douro and Algarve districts of Portugal, as compared with the other three species, P. sergenti appears to be more abundant in Evora district.(ABSTRACT TRUNCATED AT 250 WORDS)