Norbert Mencke

Epidemiological and molecular evidence supports the zoonotic transmission of Giardia among humans and dogs living in the same community.

Giardia duodenalis isolates recovered from humans and dogs living in the same locality in a remote tea-growing community of northeast India were characterized at 3 different loci; the SSU-rDNA, elongation factor 1-alpha (ef1-alpha) and triose phosphate isomerase (tpi) gene. Phylogenetic analysis of the SSU-rDNA and efl-alpha genes provided poor genetic resolution of the isolates within various assemblages, stressing the importance of using multiple loci when inferring genotypes to Giardia. Analysis of the tpi gene provided better genetic resolution and placed canine Giardia isolates within the genetic groupings of human isolates (Assemblages A and B). Further evidence for zoonotic transmission was supported by epidemiological data showing a highly significant association between the prevalence of Giardia in humans and presence of a Giardia-positive dog in the same household (odds ratio 3.01, 95% CI, 1.11, 8.39, P = 0.0000).

The prevalence, intensities and risk factors associated with geohelminth infection in tea‐growing communities of Assam, India

Objective  To determine the prevalence, intensity and associated risk factors for infection with Ascaris, hookworms and Trichuris in three tea‐growing communities in Assam, India.

The animal reservoir of Tunga penetrans in severely affected communities of north-east Brazil

Abstract.  Tungiasis is a zoonotic ectoparasitosis caused by the sand flea Tunga penetrans L. (Siphonaptera: Tungidae). This disease is hyperendemic in poor communities of north‐east Brazil, causing considerable morbidity in affected human populations, but the animal reservoirs have not been investigated previously in Brazil. To assess the prevalence and intensity of T. penetrans infection in domestic and peri‐domestic animals, as well as in the human population, we surveyed two typical communities of north‐east Brazil: an urban slum and a traditional fishing village. In the slum we examined 849 humans, 121 cats, 82 dogs, 2 pigs, 2 rabbits, 1 monkey and 56 rodents, comprising 34 rats (Rattus rattus L.) and 22 mice (Mus domesticus L). In the fishing village we examined 505 humans, 68 dogs, 37 cats, 7 donkeys, 4 cattle, 3 pigs and 1 monkey. Tungiasis was common among dogs and cats of both communities, with respective prevalence rates of 67.1% (95% CI: 55.8–77.1) and 30.9% (95% CI: 20.2–43.3) in dogs, 49.6% (95% CI: 40.4–58.8) and 32.4% (95% CI: 18.0–49.8) in cats. Slum rats were 41.2% (95% CI: 24.6–59.3) infested, but the other animals were not. Human prevalence rates were 54.4% (95% CI: 51.0–57.8) in the slum and 52.1% (95% CI: 47.6–56.5) in the fishing village. High prevalence rates (range 31–67%) of tungiasis in humans, pets and rats (but apparently not other animals) indicate the need for an eco‐epidemiological approach to control of this anthropo‐zoonotic problem.

Repellent efficacy of a combination containing imidacloprid and permethrin against sand flies ( Phlebotomus papatasi ) in dogs

Infection in dogs and humans with the protozoan parasite Leishmania are widespread in tropical and subtropical countries around the globe. Sand flies of the order Phlebotomus in the Old World and Lutzomyia in the New World function as the vector of this disease. In dogs, skin lesions are the most prominent signs of canine leishmaniasis, besides other complex underlying manifestations. To prevent dogs from sand fly bites and thus transmission of Leishmania, an imidacloprid 10% w/v / permethrin 50% w/v combination was evaluated for its insecticidal and repellent efficacy. Treated and untreated control dogs were exposed weekly to about 200 female Phlebotomus papatasi for a period of four weeks. Dead and alive sand flies were counted for surviving rate evaluation and feeding rate was determined for repellency evaluation. The repellent efficacy was 94.6% (day 1), 93.3% (day 8), 80.0% (day 15), 72.8% (day 22) and 55.9% (day 29).The insecticidal efficacy was 60.0% (day 1), 46.2% (day 8), 42.6% (day 15), 35.2% (day 22) and 29.3% (day 29). The study demonstrated the high repellent potential of the imidacloprid / permethrin combination, thus protecting dogs from sand fly bites.

Prevention of endemic canine vector-borne diseases using imidacloprid 10% and permethrin 50% in young dogs: a longitudinal field study.

Canine vector-borne diseases (CVBDs) are highly prevalent and increasing in distribution worldwide. A longitudinal study was conducted in southern Italy to determine the incidence of and protection against CVBD-causing pathogens in dogs treated with a combination of imidacloprid 10% and permethrin 50% (ImPer). One hundred eleven autochthonous young dogs were divided into group A (n=63) and group B (n=48), both groups containing dogs positive and negative for one or more CVBD-causing pathogens. Additionally, 10 naïve male beagles were introduced in each group in May 2008. Group A was treated with ImPer on day 0 and every 21+/-2 days whereas group B was left untreated. Blood and skin samples were collected at baseline (March-April 2008) and at the first, second and third follow-up times (July and October 2008 and April 2009). Bone marrow was sampled at baseline and at the third follow-up. Serological, cytological and molecular tests were performed to detect Anaplasma platys, Babesia spp., Bartonella spp., Dirofilaria immitis, Ehrlichia canis, Hepatozoon canis and Leishmania infantum. Ectoparasites (fleas, ticks, and sand flies) were monitored throughout the study. The baseline prevalence of CVBDs was 39.6% with 44 dogs positive for at least one pathogen. A. platys (27.5%) and Babesia spp. (15.6%) were the most prevalent species and co-infections with up to two pathogens were detected in 16 (14.7%) individuals. At the end of the evaluation period, there was a 90.7% reduction in overall CVBD incidence density rate (IDR) in group A, as following: 100% reduction in L. infantum; 94.6% in E. canis; 94.4% in Babesia spp.; and 81.8% in A. platys. Initially positive treated dogs showed significantly lower pathogen prevalence at the third follow-up than untreated ones. At the end of the evaluation period, 8 of the 10 untreated beagles were infected with at least one pathogen whereas one of the treated beagles was A. platys positive at a single time point (second follow-up). Overall efficacy against ticks was 97.9%. In October 2009, samples were collected from the remaining 83 dogs (44 from group A and 39 from group B) to investigate the annual incidence of CVBDs in the same, at this time untreated, dog population. A high year incidence for tick-borne diseases (78.1%) and for L. infantum (13.6%) was detected in dogs from group A, seven months after the treatment had been withdrawn. The results demonstrate that ImPer preventive treatment against arthropods protects autochthonous and naïve beagle dogs against CVBD-causing pathogens.

Diagnosis of Canine Vector-Borne Diseases in Young Dogs: a Longitudinal Study

ABSTRACT Canine vector-borne diseases (CVBDs) pose a diagnostic challenge, particularly when a dog is coinfected with more than one pathogen. The purpose of this study was to generate information about the diagnosis of CVBDs in young dogs following their first exposure to flea, tick, sand fly, louse, and mosquito vectors. From March 2008 to May 2009, 10 purpose-bred young naive beagle dogs and a cohort of 48 mixed-breed dogs living in an area to which CVBD is endemic in southern Italy were monitored using different diagnostic tests (cytology, serology, and PCR). Overall, PCR detected the highest number of dogs infected with Anaplasma platys, Babesia vogeli, and Ehrlichia canis, whereas seroconversion was a more sensitive indicator of exposure to Leishmania infantum. For A. platys infection, combining blood and buffy coat cytology in parallel enhanced the relative sensitivity (SErel) (87.3%). For B. vogeli, the best diagnostic combination was buffy coat cytology and serology used in parallel (SErel, 67.5%), whereas serology and PCR used in parallel (SErel, 100%) was the best combination for L. infantum. Overall, 12 (20.7%) dogs were coinfected; however, the percentage of new coinfections decreased from baseline (50%) to the first (33.3%) and second (16.6%) follow-up time points. Numbers of coinfections with A. platys and B. vogeli were significantly higher (P < 0.05) than coinfections with other pathogen combinations. The data generated in this study provide insights on the incidence of certain pathogens infecting young dogs in southern Italy, highlight important diagnostic testing limitations, and support the use of multiple diagnostic modalities when attempting to confirm a tick-borne infection in an individual dog or in a canine population.

Seasonal dynamics of the brown dog tick, Rhipicephalus sanguineus, on a confined dog population in Italy

This study evaluated the seasonal dynamics of Rhipicephalus sanguineus (Latreille) (Acari: Ixodidae) on naturally infested dogs in a private shelter in southern Italy. From March to May 2008, 39 autochthonous mixed‐breed young dogs and 10 beagles were enrolled in the study. From March 2008 until March 2009, every 21 ± 2 days, 11 body sites of each dog were checked for ticks. At each follow‐up, the number of ticks, their developmental stage, sex and location on the dogs body were recorded. Adult ticks were found throughout the year, but immatures were absent in January and February. The adult tick population increased from July to August, whereas the load of immatures increased in early July and peaked in September, which suggests that R. sanguineus develops one generation per year in this area. The mean number of immature ticks per infested dog was higher than that of adults from March to October 2008. Ears, interdigital areas and armpits were the most frequent attachment sites of adult ticks. At the last follow‐up, a total of 2266 ticks were collected and identified as R. sanguineus. The results suggest that R. sanguineus develops one generation per year in the study area, but that it infests dogs in all seasons. This information should be taken into account when planning control programmes against this tick species and the pathogens it transmits.

Editorial: Cutaneous larva migrans and tungiasis: the challenge to control zoonotic ectoparasitoses associated with poverty.

The great majority of tropical diseases is – in one way or another – intricately linked to poverty. There is convincing evidence that, for example, intestinal helminthiases, systemic worm diseases such as schistosomiasis and lymphatic filariasis, but also protozoal and bacterial diseases (among others, malaria, amoebiasis, Chagas disease and tuberculosis) are disproportionally more common in poor populations and that the morbidity associated with these infections is particularly high in deprived communities (Bradley 1997; Guerrant & Blackwood 1999; Traub et al. 2002). The complex relationships between poverty and parasitic infections are well recognized, and initiatives addressing these issues have been in existence for a long time. The African Onchocerciasis Control Program, the Southern Cone Initiative against Chagas disease, the Intestinal Helminths Control Program and the Roll Back Malaria Program, to name just a few, are goal-oriented programmes conceived to relieve poverty-stricken populations from the burden of parasitic diseases (Kumate 1997; Albonico et al. 1999; Colley 2000). It therefore comes as a surprise that ectoparasitoses, a group of parasitic diseases which have afflicted poor populations since ancient times, are not even mentioned when important health threats and means for interventions are discussed (Visschedijk & Siméant 1998; Colley 2000). By consequence, the issue of ectoparasite control in deprived populations has rarely been addressed and was never dealt with comprehensively (Taplin et al. 1991; McCrindle et al. 1996; Carapetis et al. 1997; Figueroa et al. 1998). Of the six major parasitic skin diseases – human scabies, pediculosis, flea infestation, tungiasis, cutaneous larva migrans (CLM) and myiasis – only the first two are not zoonoses. Whereas for scabies and pediculosis, control measures only need to target the human host, the other ectoparasites require consideration of an animal reservoir. Obviously, the existence of an animal reservoir together with a complex life cycle make interventions more challenging. Cutaneous larva migrans (creeping eruption) is caused by penetration of hookworm larvae, usually from dogs or cats, into the skin of humans. Infection occurs after contact with soil contaminated by animal faeces. As man is not an appropriate host, larvae cannot reach their programmed destination and migrate in the epidermis for up to several weeks. Thus, creeping eruption is a self-limited disease. However, as almost invariably itching is severe, CLM disturbs the patient’s sleep for a prolonged period. Secondary infection, particularly because of scratching, is common in poor settings (J. Heukelbach, unpublished observation). Cutaneous larva migrans is endemic in many poor communities in tropical and subtropical countries and sporadically occurs in temperate climates (Roest & Ratnavel 2001; Klose et al. 1996). In scientific literature CLM is usually referred to as an exotic disease of travellers returning from the tropics where tourists acquire the infection on beaches frequented by stray dogs (Jelinek et al. 1994; Blackwell & Vega-Lopez 2001). Outbreaks in groups of tourists with more than a hundred infected individuals have been reported (Tremblay et al. 2000). The only risk factor identified so far is walking barefoot (Tremblay et al. 2000). Surprisingly, even in textbooks the disease is not mentioned as a typical plague of deprived populations. Close human bonds with dogs and cats infected with Ancylostoma spp. explain the frequent occurrence of Tropical Medicine and International Health

Canine antibody response to Phlebotomus perniciosus bites negatively correlates with the risk of Leishmania infantum transmission.

Background Phlebotomine sand flies are blood-sucking insects that can transmit Leishmania parasites. Hosts bitten by sand flies develop an immune response against sand fly salivary antigens. Specific anti-saliva IgG indicate the exposure to the vector and may also help to estimate the risk of Leishmania spp. transmission. In this study, we examined the canine antibody response against the saliva of Phlebotomus perniciosus, the main vector of Leishmania infantum in the Mediterranean Basin, and characterized salivary antigens of this sand fly species. Methodology/Principal Findings Sera of dogs bitten by P. perniciosus under experimental conditions and dogs naturally exposed to sand flies in a L. infantum focus were tested by ELISA for the presence of anti-P. perniciosus antibodies. Antibody levels positively correlated with the number of blood-fed P. perniciosus females. In naturally exposed dogs the increase of specific IgG, IgG1 and IgG2 was observed during sand fly season. Importantly, Leishmania-positive dogs revealed significantly lower anti-P. perniciosus IgG2 compared to Leishmania-negative ones. Major P. perniciosus antigens were identified by western blot and mass spectrometry as yellow proteins, apyrases and antigen 5-related proteins. Conclusions Results suggest that monitoring canine antibody response to sand fly saliva in endemic foci could estimate the risk of L. infantum transmission. It may also help to control canine leishmaniasis by evaluating the effectiveness of anti-vector campaigns. Data from the field study where dogs from the Italian focus of L. infantum were naturally exposed to P. perniciosus bites indicates that the levels of anti-P. perniciosus saliva IgG2 negatively correlate with the risk of Leishmania transmission. Thus, specific IgG2 response is suggested as a risk marker of L. infantum transmission for dogs.

Evolution of clinical, haematological and biochemical findings in young dogs naturally infected by vector-borne pathogens.

Longitudinal studies evaluating the evolution of clinical, haematological, biochemical findings in young dogs exposed for the first time to multiple vector-borne pathogens have not been reported. With the objective of assessing the evolution of clinical, haematological and biochemical findings, these parameters were serially monitored in naturally infected dogs throughout a 1-year follow-up period. Young dogs, infected by vector-borne pathogens based on cytology or polymerase chain reaction, were examined clinically and blood samples were obtained at seven different follow-up time points. Dogs were randomized to group A (17 dogs treated with a spot-on formulation of imidacloprid 10% and permethrin 50%) or to group B (17 dogs untreated). In addition, 10 4-month-old beagles were enrolled in each group and used as sentinel dogs. At baseline, Anaplasma platys was the most frequently detected pathogen, followed by Babesia vogeli, Bartonella spp., Ehrlichia canis and Hepatozoon canis. Co-infections with A. platys and B. vogeli, followed by E. canis and B. vogeli, A. platys and H. canis and A. platys and Bartonella spp. were also diagnosed. In dogs from group B, abnormal clinical signs were recorded at different time points throughout the study. No abnormal clinical signs were recorded in group A dogs. Thrombocytopenia was the most frequent haematological alteration recorded in A. platys-infected dogs, B. vogeli-infected dogs and in dogs co-infected with A. platys and B. vogeli or A. platys and Bartonella spp. Lymphocytosis was frequently detected among dogs infected with B. vogeli or co-infected with A. platys and B. vogeli. Beagles were often infected with a single pathogen rather than with multiple canine vector-borne pathogens. There was a significant association (p<0.01) between tick infestation and A. platys or B. vogeli, as single infections, and A. platys and B. vogeli or A. platys and Bartonella spp. co-infections. This study emphasizes the clinical difficulties associated with assigning a specific clinical sign or haematological abnormality to a particular canine vector-borne disease.