Estimation of canine Leishmania infection prevalence in six cities of the Algerian littoral zone using a Bayesian approach

Global Distribution of Canine Visceral Leishmaniasis and the Role of the Dog in the Epidemiology of the Disease

Visceral leishmaniasis is a disease caused by protozoa of the species Leishmania (Leishmania) infantum (syn = Leishmania chagasi) and Leishmania (Leishmania) donovani, which are transmitted by hematophagous insects of the genera Lutzomyia and Phlebotomus. The domestic dog (Canis familiaris) is considered the main urban reservoir of the parasite due to the high parasite load on its skin, serving as a source of infection for sandfly vectors and, consequently, perpetuating the disease in the urban environment. Some factors are considered important in the perpetuation and spread of canine visceral leishmaniasis (CVL) in urban areas, such as stray dogs, with their errant behavior, and houses that have backyards with trees, shade, and organic materials, creating an attractive environment for sandfly vectors. CVL is found in approximately 50 countries, with the number of infected dogs reaching millions. However, due to the difficulty of controlling and diagnosing the disease, the number of infected animals could be even greater. In the four continents endemic for CVL, there are reports of disease expansion in endemic countries such as Brazil, Italy, Morocco, and Tunisia, as well as in areas where CVL is not endemic, for example, Uruguay. Socio-environmental factors, such as migration, drought, deforestation, and global warming, have been pointed out as reasons for the expansion into areas where it had been absent. Thus, the objective of this review is to address (i) the distribution of CVL in endemic areas, (ii) the role of the dog in the visceral leishmaniasis epidemiology and the factors that influence dog infection and the spread of the disease, and (iii) the challenges faced in the control of CVL.

Diagnosis and prevalence of canine leishmaniasis in the Atlas shepherd dog

The aim of this study was to determine the prevalence of canine leishmaniasis in the Atlas shepherd dogs from the Tiaret region of Algeria. A total of 161 dogs were included in this study and four diagnostic techniques were used, namely lymph node cytology, PCR, IFAT and ELISA. 110 out of 161 dogs were positive by at least one diagnostic technique, a percentage of 68.32% of the total number, which represent very high prevalence of canine leishmaniasis in this canine breed. 152 dogs underwent the two serological tests namely IFAT and ELISA among which 137 dogs underwent in addition the molecular examination by PCR. IFAT was positive in 9.86% of the dogs, ELISA was positive in 12.5% while 68% of the dogs proved positive by PCR. 47 dogs with lymph node enlargement underwent lymph node cytology, of which 26 dogs showed forms of amastigotes in their smears after microscopic examination, confirming the usefulness of this approach for the diagnosis of canine leishmaniasis. The clinical signs of the disease in this breed are similar to those of other canine breeds The dominant clinical signs in these dogs were onychogryphosis, poor general condition and lymph node hypertrophy. The autopsy was carried out on 7 dogs that died of canine leishmaniasis, all of which showed splenomegaly, while 5 dogs also showed hepatomegaly. Renal damage was found in 1 dog with frank jaundice. The splenic cytology was positive in all 7 dogs with the presence of amastigote forms in the smears after microscopic examination.

Identification of blood source preferences and Leishmania infection in sand flies (Diptera: Psychodidae) in north-eastern Algeria

Leishmaniases are among the most neglected vector-borne diseases, infecting humans as well various animal hosts with clinical outcomes varying from cutaneous disorders to visceral and life-threatening disease. In Algeria, canine leishmaniasis (CanL) caused by Leishmania infantum is endemic mainly throughout the northern regions of the country with the Mediterranean climate that favours the occurrence of Larroussius sand flies, the vectors of the parasite. This study conducted in Bougaa and Kherrata, two regions located in north-eastern Algeria and endemic for CanL, focuses on: i) composition of sand fly fauna, ii) screening of Leishmania parasites and iii) the blood sources of engorged females. Entomological surveys were conducted between June and September 2019 using CDC light-traps in rural areas of both regions. Sand fly specimens were morphologically identified, females were screened for Leishmania DNA using kDNA and ITS1 primers, blood meals in engorged females were identified by peptide mass mapping (PMM)-based MALDI-TOF mass spectrometry and confirmed by DNA sequencing analysis. Overall, 1940 specimens (844 males, 1096 females) were collected, all belonging to the subgenus Larroussius: Phlebotomus perniciosus, (94.64%), Ph. perfiliewi (4.74%) and Ph. longicuspis (0.62%). No Leishmania DNA was detected in the evaluated pools (n = 106) (1096 females). PMM-based MALDI-TOF MS successfully identified a source of blood in 92% (141/154) of engorged females (135 Ph. perniciosus and 6 Ph. perfiliewi). All blood meals were taken from domestic cattle (Bos taurus) except for one originating from a dog (Canis lupus familiaris) and one from sheep (Ovis aries). Sequencing of host cytochrome B gene confirmed these identifications but showed lower success rate of 58% (29/50), demonstrating the high effectivity of peptide mass mapping (PMM)-based MALDI-TOF mass spectrometry for routine identification of blood meals of varying degree of digestion. Our findings represent first record of cattle and dog blood in sand flies in Algeria and striking feeding preference of local sand fly population at domestic sites of studied regions for cattle which may play an important role in parasite transmission. Further studies are needed to better understand potential contribution of cattle to ecology of sand flies and epidemiology of leishmaniasis in north-eastern Algeria.

Potential of Artesunate in the treatment of visceral leishmaniasis in dogs naturally infected by Leishmania infantum: Efficacy evidence from a randomized field trial

Leishmaniasis is among the world’s most neglected diseases. Dogs are the main reservoirs/hosts of Leishmania infantum, causative agent of both canine and human visceral leishmaniosis. Canine leishmaniasis (CanL) represents a public health problem as one of the most prevalent zoonotic diseases worldwide. Current therapeutics present drawbacks; thus, there is a need for more effective, safer, and cheaper drugs. The aim of this study was to evaluate and to compare the efficacy of oral administration of artesunate or meglumine antimoniate/allopurinol in dogs with clinical leishmaniasis. Forty-two dogs with naturally occurring clinical leishmaniasis were included in this open-label, simple randomized positive-control clinical field trial with 6 months of follow-up. Dogs received meglumine antimoniate 100 mg/kg/day and allopurinol 30 mg/kg/day for 28 days (control group, n = 26) or artesunate 25 mg/kg/day for 6 days (test group, n = 16). The animals were evaluated for their clinical evolution, parasite load (by qPCR) and humoral response at different time points: 0, 30, 90, and 180 days after treatment. Data analyses showed a significant improvement in both groups in clinical scores, parasitemia and antibody titers after treatment. Compared to the control group, the artesunate group showed significantly lower clinical score (P = 0.0001), lower parasitemia (P = 0.0001) and antibody titers after 6 months of follow-up. Compared to baseline values, a rapid, significant reduction (P < 0.012) in antibody levels, 2.28- versus 3.04-fold for the control versus artesunate groups, respectively, was observed 30 days after treatment. Antibody levels continued to decrease further in the artesunate group, where 58% of cases became seronegative at the 6-month follow-up. All qPCR-positive dogs were negative after treatment with artesunate, while 14.3% remained positive with the appearance of two new cases in the control group. Artesunate was well tolerated, and no side effects were recorded. Treatment failures were similar in both groups with 27.27% (6/22), including 18.18% (4/22) mortality in the control group, versus 26.66% (4/15), including 13.33% (2/15) mortality in the artesunate group. This is the first report showing the potential of artesunate in the treatment of dogs with clinical leishmaniasis. Artesunate showed higher efficacy than the current first-line treatment for CanL without any adverse effects. It could be a good alternative chemotherapy for CanL, and may be considered for further studies in human leishmaniases. Further clinical trials are needed to confirm these findings, to determine if there are relapses after treatment and if dogs remain infective to sandflies, to define the ideal therapeutic dosage and duration of treatment with artesunate.

Canine leishmaniasis (CanL) is a fatal, zoonotic vector-borne disease caused by Leishmania infantum, a common pathogen for both humans and dogs. Most CanL therapeutics are toxic, expensive, or ineffective. Artemisinin and derivatives have recently demonstrated potent antileishmanial activity in vitro and in experimental models. In this study, dogs with clinical leishmaniasis were randomly included in one of the treatment groups: meglumine antimoniate/allopurinol (control) or artesunate (alternative). Dogs were followed up for 6 months for their clinical score, parasitemia and Leishmania antibody levels. Both groups showed improved clinical scores, parasitemia and antibody titers after treatment. After six months of follow-up, treatment success was very similar in both groups, and 72.73% (16/22) of the controls versus 73.34% (11/15) in the artesunate group had clinical improvement. All dogs initially seropositive by PCR became negative after artesunate treatment, while 14.3% remained positive with the appearance of new cases in the control group. Antibody titers decreased rapidly (from day 30) from baseline especially in the artesunate group, where 58% of the dogs converted to seronegative after 6 months. Artesunate could be a good alternative for treatment of leishmaniasis. Additional clinical trials are needed to obtain more data on this drug.

Molecular and serological detection of animal and human vector-borne pathogens in the blood of dogs from Côte d'Ivoire

In Côte d'Ivoire, limited information are available on vector-borne pathogens, their prevalence and distribution. Here, we assess the occurrence and diversity of canine vector-borne diseases (CVBDs) in Abidjan and Yamoussoukro cities. Blood from a total of 123 dogs were tested for Leishmania infantum and Ehrlichia canis antibodies and screened for Leishmania and Trypanosoma spp., Piroplasmida, Filariidae and Anaplasmataceae by PCR and sequencing. Among dogs, 39 % were positive for at least one pathogen. Seroprevalences were: 15.4 % and 12.2 % for L. infantum and E. canis, respectively. DNA of L. infantum and T. congolense (4.1 %), Baabesia vogeli (1.6 %), Filariidae (Dirofilaria immitis, D. repens and Acanthocheilonema reconditum) (10.6 %) has been detected. Anaplasmataceae were detected in (17.1 %) and E. canis was the only identified specie. Co-infections were observed in 13.8 % of dogs: E. canis-L. infantum co-infection was the most prevalent (4.9 %). Age, breed and sex of dogs do not seem to influence infections. Village dogs were more susceptible to CVBDs than kennel dogs (PV = 0.0000008). This study reports for the first time the presence of L. infantum, B. vogeli, A. reconditum, D. immitis and D. repens in dogs from Côte d'Ivoire and determines the prevalence and diversity of CVBD pathogens. The results indicate that human and animal pathogens are abundant in Ivoirian dogs which requires attention of veterinarians, physicians and authorities against these diseases, especially against major zoonosis such as visceral leishmaniasis (L. infantum).

Canine vector-borne protozoa: Molecular and serological investigation for Leishmania spp., Trypanosoma spp., Babesia spp., and Hepatozoon spp. in dogs from Northern Algeria

Dogs are competent reservoirs/hosts of several protozoan pathogens transmitted by blood-feeding arthropods. Throughout their long history of domestication, they have served as a link for the exchange of parasites among livestock, wildlife, and humans and therefore remain an important source of emerging and re-emerging diseases. In Algeria, while canine leishmaniosis (CanL) is well known to be endemic, no data are available on other vector-borne protozoans. Here, we investigate the occurrence and diversity of trypanosomes, piroplasms and Hepatozoon spp. and update the epidemiological status of CanL in dogs from Kabylia, northern Algeria. A total of 227 dogs from three regions of Kabylia were enrolled, including 77 dogs with clinical signs. Dogs were clinically examined and were tested for L. infantum antibodies using a Rapid Immuno-Migration (RIM™) and a quantitative indirect Immunofluorescence Antibody Test (IFAT). PCR screening and sequencing were performed for vector-borne protozoa. Sixty two percent (141/227) of dogs presented at least one infection, whereas 26% (59/227) were co-infected. L. infantum antibodies were detected in 35.7% (81/227) of dogs including 88.7% (68/77) of sick dogs. Molecular investigation revealed prevalence of: 6.6% (15/227), 13.2% (30/227), 41% (93/227) for Trypanosoma spp., B. vogeli and H. canis, respectively. T. evansi (3.1%) and potential new subspecies of T. congolense had been identified. Dog''s clinical status correlates positively with L. infantum antibody titers and the presence of co-infections. Susceptibility to CanL varied according to the dog's aptitude and guard dogs were more infected (51%) (P-value = .001). B. vogeli infection was more frequent in juveniles than adults (32% vs 9%, P-value < .001) and in females than males (21% vs 10%, P-value = .02). To the authors' knowledge, this is the first report on vector-borne protozoa infected dogs in Algeria. Current results are important not only for animal health, but also to avoid serious public health and livestock problems.

Epidemiological investigations on Trypanosoma evansi infection in dromedary camels in the South of Algeria

An epidemiological study of Trypanosoma evansi (T. evansi) infection in dromedaries was conducted in four wilayate (localities) of Southern Algeria: Béchar, El Bayadh, Ouargla, Tamanrasset. Between February 2014 and April 2016, 1056 camels of different ages and both sexes from 84 herds were sampled. The prevalence was determined through parasitological examination (Giemsa stained thin smear, GST), serological tests (CATT/T. evansi, ELISA/VSG RoTat 1.2, immune trypanolysis), and molecular tests (T. evansi type A specific RoTat 1.2 PCR and T. evansi type B specific EVAB PCR). The overall prevalence was 2.4 % with GST, 32.4% with CATT/T. evansi, 23.1% with ELISA/VSG RoTat 1.2, 21.0% with immune trypanolysis (TL), 11.2 % with RoTat 1.2 PCR and 0% with EVAB PCR. El Bayadh was the most affected wilaya with 11.8% positives in GST, 74.9% in CATT/T. evansi, 70.1% in ELISA/VSG RoTat 1.2 and 62.2% in immune trypanolysis. Only in Béchar, a non-significantly higher prevalence (13.6%) was observed with RoTat1.2 PCR than in El Bayadh (13.0%). We didn't find any evidence of the presence of T. evansi type B in the study area.

Epidemiology of dog-mediated zoonotic diseases in Algeria: a One Health control approach

Globally, human–dog interactions cause significant social, economic and human health costs. Public health problems linked with dogs include mainly zoonotic diseases. Recently the concept of a global and integrative approach to improve the health and well-being of people, animals and the environment has been strongly endorsed. This concept, often referred to as One Health, also reflects the collaboration in the field of surveillance and monitoring. Because humans and animals often suffer from the same pathogens and share the same environment, a cross-sector approach integrating human and animal disease surveillance information is required. The aims of the present study were to describe the incidence of dog-mediated zoonotic diseases in Algeria between 2010 and 2017, and to propose a One Health approach to control these diseases in Algeria. Rabies, leishmaniasis and echinococcosis are the major zoonoses in Algeria, with a reported average number of deaths per year, respectively, of 18, 7947 and 387. These zoonoses occur with the uncontrolled proliferation of household waste deposits, particularly in and around urban area which maintain the presence of stray dogs. The persistence of these diseases indicates the need for greater partnership and collaboration among multiple sectors, including medical doctors, veterinarians, ecologists, environmentalists and law-enforcement agents. Such partnerships permit the sharing of information, facilities and resources under a One Health approach; permit rapid communication among disciplines as well as interdisciplinary training/education opportunities and raising awareness among human population; and allow a combined effort towards disease surveillance/control, which will consequently improve the efficiency of the control programmes.

Evaluation of Immunofluorescence Antibody Test Used for the Diagnosis of Canine Leishmaniasis in the Mediterranean Basin: A Systematic Review and Meta-Analysis

With an expected sensitivity (Se) of 96% and specificity (Sp) of 98%, the immunofluorescence antibody test (IFAT) is frequently used as a reference test to validate new diagnostic methods and estimate the canine leihmaniasis (CanL) true prevalence in the Mediterranean basin. To review the diagnostic accuracy of IFAT to diagnose CanL in this area with reference to its Se and Sp and elucidate the potential causes of their variations, a systematic review was conducted (31 studies for the 26-year period). Three IFAT validation methods stood out: the classical contingency table method, methods based on statistical models and those based on experimental studies. A variation in the IFAT Se and Sp values and cut-off values was observed. For the classical validation method based on a meta-analysis, the Se of IFAT was estimated in this area as 89.86% and 31.25% in symptomatic and asymptomatic dogs, respectively. The Sp of IFAT was estimated in non-endemic and endemic areas as 98.12% and 96.57%, respectively. IFAT can be considered as a good standard test in non-endemic areas for CanL, but its accuracy declines in endemic areas due to the complexity of the disease. Indeed, the accuracy of IFAT is due to the negative results obtained in non-infected dogs from non-endemic areas and to the positive results obtained in sera of symptomatic dogs living in endemic areas. But IFAT results are not unequivocal when it comes to determining CanL infection on asymptomatic dogs living in endemic areas. Statistical methods might be a solution to overcome the lack of gold standard, to better categorize groups of animals investigated, to assess optimal cut-off values and to allow a better estimate of the true prevalence aiming information on preventive/control measures for CanL.