Laura Tomassone

Borrelia lusitaniae in Immature Ixodes ricinus (Acari: Ixodidae) Feeding on Common Wall Lizards in Tuscany, Central Italy

Abstract Lizards and small rodents were live captured in Tuscany, central Italy, from May through August 2005. Prevalence of infestation by larval Ixodes ricinus L. (Acari: Ixodidae) and mean numbers of larvae per host were not significantly different for common wall lizards, Podarcis muralis Laurenti, and Apodemus spp. mice, whereas infestation levels by nymphs were significantly greater on lizards. Borrelia lusitaniae, which was previously shown to be dominant in host-seeking I. ricinus in the same study area, was detected by polymerase chain reaction (PCR) in 19.8% (95% confidence interval: 14.4, 26.0) of larval ticks and in 52.9% (27.8, 77.0) of nymphs that were collected from lizards. Moreover, 18.8% (7.2, 36.4) and 25.0 (3.2, 65.1) of lizards’ tail biopsies and blood samples, respectively, were positive for B. lusitaniae. Conversely, attached ticks and ear biopsies from Apodemus spp. mice were PCR negative. Passerine birds belonging to 10 species were live captured in March 2005, and Borrelia valaisiana was detected in 57.1% (18.4, 90.1) of I. ricinus nymphs feeding on Eurasian blackbirds, Turdus merula L. Results of this study suggest that lizards play an important role as reservoirs for B. lusitanae and may affect the dominance of this genospecies in the Mediterranean area.

Borrelia lusitaniae and Spotted Fever Group Rickettsiae in Ixodes ricinus (Acari: Ixodidae) in Tuscany, Central Italy

Abstract Prevalence of infection by Borrelia burgdorferi s.l. and spotted fever group (SFG) rickettsiae was estimated in host-seeking ticks in an area in Tuscany, central Italy, where Lyme borreliosis was reported in a forestry worker. B. burgdorferi s.l. was identified by polymerase chain reaction in 16.7% (95% CI = 10.3, 24.8) of Ixodes ricinus (L.) nymphs and 39.6% (95% CI = 26.5, 54.0) of adults. Borrelia lusitaniae accounted for 82.9% of positive samples, followed by Borrelia garinii (9.8%), Borrelia afzelii (2.4%), and Borrelia burgdorferi s.s. (2.4%). One Rhipicephalus spp. adult was infected with B. garinii (prevalence = 8.3%; 95% CI = 0.21, 38.5). Prevalence of infection by SFG rickettsiae was 38.5% (95% CI = 26.7, 51.4) in I. ricinus nymphs, 34.6% (95% CI = 22.0, 49.1) in I. ricinus adults, and 50% (95% CI = 21.1, 78.9) in Rhipicephalus spp. adults. Phylogenetic analysis showed the similarity of B. lusitaniae strains that were identified in this study and of a strain that was previously isolated from a human patient in Portugal. Results of this study confirm the dominance of B. lusitaniae in areas in the Mediterranean basin and the infection by SFG rickettsiae in I. ricinus.

Rickettsia slovaca and Rickettsia raoultii in Dermacentor marginatus Ticks Collected on Wild Boars in Tuscany, Italy

ABSTRACT During the hunting season 2007–2008, 494 Dermacentor marginatus (Sulzer) ticks were collected from 109 hunter-killed wild boars, Sus scrofa, in Luccas province, Tuscany, Italy. Rickettsia slovaca, the causative agent of tick-borne lymphadenopathy (TIBOLA), was detected in 32.1% of ticks tested (n = 112) by using polymerase chain reaction primers targeting gltA, ompA, and ompB rickettsial genes. Moreover, Rickettsia raoultii was found for the first time in Italy, with 1.8% infection prevalence. This study confirms the risk posed to humans by ticks and tick-borne pathogens in the study area, where cases of spotted fever rickettsiosis (TIBOLA) are reported.

Borrelia burgdorferi sensu lato Infection in Larval Ixodes ricinus (Acari: Ixodidae) Feeding on Blackbirds in Northwestern Italy

Abstract Birds belonging to 59 species (n = 1,206) were live captured in Piemonte, northwestern Italy, in 2001. Ixodes ricinus (L.) larvae were collected from 59 birds belonging to nine species, and nymphs were recovered on 79 birds belonging to 10 species. Eurasian blackbirds, Turdus merula L., had significantly higher levels of infestation by ticks than other passerine species. Larval I. ricinus of blackbirds peaked in summer, when prevalence was 39% (95% confidence interval 24.2–55.5) and mean number of ticks per host was 3.3 (1.6–7.2), whereas nymphs peaked in spring, when prevalence was 72.2% (54.8–85.8) and mean number of ticks per host was 6.9 (4.4–10.7). Immature I. ricinus were coincidentally aggregated on blackbirds, with 15 blackbirds feeding 67.4% of nymphs and 40.3% of larvae, and coinfestation by both stages was relatively high in summer: Kappa = 0.64 (0.40–0.88). Borrelia burgdorferi sensu lato was identified by polymerase chain reaction (PCR) in 58.3% (35.9–78.5) of larvae with engorgement ratio ≥3 that were collected from blackbirds. Larvae that were collected from other passerine species gave negative PCR results. Sixteen of 21 PCR-positive samples belonged to B. garinii (76.2%), and five (23.8%) were Borrelia valaisiana. Results of this study suggest that blackbirds play an important role as hosts for immature I. ricinus and as reservoir of Borrelia garinii in northwestern Italy.

Temporal Variations in the Usefulness of Normalized Difference Vegetation Index as a Predictor for Ixodes ricinus (Acari: Ixodidae) in a Borrelia lusitaniae Focus in Tuscany, Central Italy

Abstract Host-seeking ticks were collected during monthly dragging sessions from November 2004 through October 2006 in Tuscany, central Italy. Normalized difference vegetation index (NDVI), which was calculated from Landsat ETM+ 7 remote sensing data recorded in August 2001, was significantly correlated with numbers of host-seeking immature Ixodes ricinus L. (Acari: Ixodidae) during periods of relatively low rainfall such as summer 2005 (Spearman’s ρ = 0.78, P < 0.001 for nymphs in July) and to a lower extent in spring–summer 2006. In spring 2005, when rainfall was relatively high, the correlation was weak and not statistically significant. Generalized estimating equations (GEEs), taking into account repeated sampling of the same dragging sites, were used to model the effects of NDVI and season on counts of host-seeking I. ricinus nymphs. Seasonal variations of the effect of NDVI yielded a significant NDVI-by-season interaction in the first year of the study (November 2004–October 2005), but not in the second year (November 2005–October 2006) when there was a 2.5-fold increase of the number of nymphs per 100-m dragging for every 0.1 unit increase in NDVI (95% confidence interval = 1.6, 3.0). Risk maps that were obtained based on GEE results confirmed that the predicted number of I. ricinus nymphs per 100 m was relatively homogeneous through the study area during the 2005 spring peak of activity. Conversely, in 2006, the predicted abundance of nymphs was greater in moist bottomland habitat (characterized by high NDVI) than in dry, typically Mediterranean, upland habitat.

Bovine cerebral theileriosis: Histological and ultrastructural investigations

Bovine cerebral theileriosis (BCT), or turning sickness is a clinical presentation of parasitic infections of cattle, caused by Theileria spp., that occurs sporadically in South Africa, Burundi, Uganda, Kenya and Tanzania. Clinical signs include circling, blindness, ataxia, opisthotonus and paralysis. The disease can be acute, subacute or chronic, and mainly affects animals between 3 and 5 years old. It is characterised by intense congestion and haemorrhages in the meninges and brain, encephalomalacia, and accumulation of parasitised lymphoblasts in cerebral blood vessels. Macroscopic, histological and ultrastructural lesions observed in 30 indigenous short-horn Zebu cattle from Northern Tanzania, aged 2–9-years-old, which presented characteristic neurological signs of a disease named “Ormilo” by local Maasai herders, were described. Brain smears, prepared from cerebral vessels and stained with Giemsa, revealed extensive lymphocytic infiltration associated with numerous schizonts. Histologically, areas of congestion and haemorrhage associated with obstruction of cerebral vessels with large numbers of parasitised lymphoblasts were the main lesions. Ultrastructural investigations demonstrated the presence of parasites morphologically comparable to flagellated protozoa inside lymphoid cells. This has never been described before in the end host (cattle), but only during the sexual stages within the gastrointestinal tract of ticks. PCR results showed positivity for Theileria taurotragi in 13 samples, suggesting that the parasite could be involved in the aetiology of Ormilo. The alternative hypothesis is that the parasite belongs to a different unknown protozoal genus, having an intra-lymphocytic phase, and being associated with infestation with Theileria spp. Further studies are needed to better understand the morphology of the parasite, its role in BCT, and its potential pathogenic importance for animals.

Detection of Rickettsia aeschlimannii and Rickettsia africae in ixodid ticks from Burkina Faso and Somali Region of Ethiopia by new real-time PCR assays

In the framework of cooperation for development projects in Burkina Faso and Ethiopia, we collected ixodid ticks from cattle, small ruminants and camels. We optimized new TaqMan Probe real-time PCR assays to detect Rickettsia aeschlimannii and Rickettsia africae OmpA gene in the collected samples. Rickettsia africae was identified in 75.0% Amblyomma variegatum (95%CI: 56.6-88.5), while R. aeschlimannii in 24.0% Hyalomma truncatum (95%CI: 9.4-45.1) and 50.0% H. rufipes (95%CI: 29.9-70.0) collected from cattle in different provinces throughout Burkina Faso. Ticks from the Libaan zone, Somali Region of Ethiopia, were also infected by R. africae (28.5% prevalence in Amblyomma gemma, 95%CI: 14.7-46.0) and R. aeschlimannii (27.0% H. truncatum, 95%CI: 5.0-62.9; 88.3% H. rufipes, 95%CI: 60.5-99.3). All tested ticks were adults. The developed diagnostic tools were highly sensitive and enabled us to rapidly classify R. aeschlimannii and R. africae, which were identified in Burkina Faso and in the Somali Region of Ethiopia for the first time. Further studies are needed to assess the zoonotic risk and prevalence of infection in local human populations, who have high contact rates with ticks and their animal hosts.