In Algeria, a North African country, CVL is present throughout the country, with the prevalence of parasites varying depending on the region [
19]. In the capital, Algiers, 37% of 1,800 dogs had positive serology for CVL between 1990 and 1997 [
20]. Also in Algiers, Adel et al. [
21] showed in a study using 462 dogs between 2004-2005 that stray dogs were those with the highest prevalence of leishmaniasis (11.7%), followed by animals from the national guard (9.7%) and those that lived on farms (5.9%). Between 2008-2009, there was an increase in the number of cases of CVL, from west to east, in the country’s coastal region between the cities of Tlemcen and Jijel [
22]. Seropositive dogs were also found in Kabylia, a region located in the north, where the rate of seropositive animals was 36% [
23], and in the Tiaret region, with 93/137 (67.88%) dogs testing positive for CVL through
Leishmania nested PCR –
LnPCR [
24].
In Tunisia, the infection of dogs by
Leishmania was first described by Nicolle and Comte [
28]. As in other countries, the prevalence of CVL varies according to the region. In the city of Medjez El Bab, Beja Governorate, the canine infection rate in 1994 and 1995 was 18% and 22.3%, respectively. It is noteworthy that 90% of the animals were asymptomatic [
29]. In Sfax, Central-South region, 250 animals were tested for CVL, with a seroprevalence rate of 6% [
30]. In the Kairouan Governorate, in the central region of the country, the prevalence was 21% in dogs from the rural area of El Alaa, in which 50% of the animals were asymptomatic [
31]. Similarly, in a study by Zoghlami et al. [
32], in seven districts of the same governorate, the overall prevalence was 26.7%. Currently, a seroprevalence of 58.3% was obtained in a study conducted by Bouattour et al
. [
33] in eight locations in different bioclimatic areas of the country. According to the authors, it is possible to conclude that there was an increase in CVL in all bioclimatic areas, in addition to confirming the spread of the disease to arid areas.
The existence of dogs infected with
Leishmania in Ethiopia has been reported in several studies (
Table 1). While in Sudanese territory, Dereure et al. [
36] were the first to advance the possibility of the dog acting as a reservoir host in Barbar El Fugarra, in the state of Gedaref, considered an endemic area for VL. At the same location, seroprevalence for leishmaniasis was observed in 72.5%, 74.3%, and 42.9% of dogs in 1998, 1999, and 2000, respectively [
37]. In contrast, a study by Hassan et al. [
38] in 10 villages along the Rahad River in 2002 showed that 6.9% of the dogs were serologically positive for
L. donovani. In the western part of the continent, cases of dogs infected with
Leishmania have been reported, mostly by
L. infantum, in Burkina Faso [
39], Côte d
’Ivoire [
40], Nigeria [
41], Senegal [
42], and Zambia, in southern Africa [
43] (
Table 1).
The Americas
In the Americas, the main etiological agent of CVL is the
L. infantum, which was introduced during the period of Portuguese and Spanish colonization through infected animals, such as dogs, that came from Europe to the New World with the colonizers [
44].
In Argentina, a country where the number of human VL cases rose in 2019, presenting nine cases (0.35% of cases in the Americans) [
45], infected dogs were found in the city of Posadas, province of Misiones [
46,
47], where Cruz et al. [
48] obtained 58.3% infection rate of dogs by
L. infantum (63/110). In Puerto Iguazú, located in the same province, 7.17% of 209 dogs evaluated were considered positive for
L. infantum [
49] and, more recently, infected dogs were identified by Fujisawa et al. [
50] and Lamattina et al. [
51], in which 28 of 160 dogs (17.5%) were found with positive serology. Similarly, in the Chaco region of Salta province, about 1,000 km away from the province of Misiones, the prevalence of CVL was 13% [
52].
Reports dated from 1982 demonstrate the presence of CVL in Bolivia, where
L. infantum was isolated from five dogs in the Yungas area, which was confirmed by serology [
53]. In Colombia, VL has two sources of transmission: in the northern departments of Sucre, Bolívar, and Córdoba, where the highest number of cases are registered; and the Middle Valley region of the Magdalena River, in the departments of Cundinamarca, Tolima, and Huila [
54]. Picón et al. [
55] found a 12% seroprevalence in 2016-2017 when analyzing dogs in the cities of Guamo, Ortega, Flanders, Coyaima, and Melgar in Tolima department and Neiva in the Huila department. Interestingly, Arbeláez et al. [
56] reported the first case of urban CVL in the city of Cali, in a dog that had never lived in an endemic area and only roamed in areas where human or canine cases of the disease had not been reported. More recently, dogs infected with
L. infantum were found in Sincelejo, in the department of Sucre [
57], as well as in Pradera and Florida, in Valle del Cauca [
58].
In the French overseas department, French Guiana, dogs with autochthonous infection by
L. infantum were reported in 2016 in Cayenne through molecular tests, with a prevalence of 3.1%. In addition, it was observed in dogs that performed military work, which had negative molecular and serological results prior to going to French Guiana, yet tested positive for infection when they returned to France after four months in the region, suggesting the possible existence of a autochthonous cycle of VL transmission in the department [
59]. In Venezuela, dogs infected with
L. infantum were found in the states of Lara and Yaracuy [
60], while in Honduras on the El Tigre island, located in Amapala, the seroprevalence of dogs infected by
L. infantum, analyzed by DPP and ELISA, reached 41%, and the presence of parasite DNA was observed in 94% of the dogs evaluated [
61].
According to PAHO, 97% of all human VL cases that occurred on the continent in 2019 were reported in Brazil [
7] and the disease continues to spread [
62,
63]. Cases of canine infection have been reported in several state capitals, or their metropolitan regions, such as Belo Horizonte [
64,
65], Boa Vista [
66], Campo Grande [
67], Cuiabá [
68,
69], Florianópolis [
70], Fortaleza [
71], Macapá [
72], Maceió [
73], Natal [
74], Niterói [
75], Porto Alegre [
76], Rio de Janeiro [
77,
78], Salvador [
79], and Vitória [
80]. The same was observed in inland cities, such as Araçatuba [
81] and Piacatu [
82] in the state of São Paulo; Divinópolis [
83] and Governador Valadares [
84,
85] in Minas Gerais; Campina Grande [
86] in Paraíba; Rondonópolis [
87] in Mato Grosso; and Santarém [
88] in the state of Pará. The seroprevalence of CVL in Brazil varies from 4% to 75%, being related to geographic conditions, climate, and social aspects of the affected area [
89].
It is known that the disease has reached areas where it had previously not been present. The expansion of CVL to non-endemic regions can be illustrated by reports, such as the autochthonous outbreak that occurred in Arenitas Blancas, in the department of Salto, Uruguay, where 22% of the animals studied tested positive for leishmaniasis [
90]. Other cases have been reported in Canada and the United States [
91,
92,
93,
94,
95,
96,
97].
Asia
VL on the Asian continent is caused by
L. infantum in the Middle East and Central Asia and
L. donovani in the Indian subcontinent, a region that harbors the most cases in the world [
98,
99,
100].
In Iran, VL is distributed in three foci, located in four provinces in the northwest and south and, recently, it has spread to other parts of the country [
101,
102]. The prevalence of CVL in endemic areas ranges from 14.2% to 17.4% [
101], and several studies have shown the distribution of infected dogs throughout Iran (
Table 1).
After more than 30 years without the occurrence of human and canine infection, cases of CVL in Israel were reported by Baneth et al. [
103]. Nasereddin et al. [
104] isolated strains of Leishmania, mainly
L. infantum, in dogs in the northern and central regions of the country, as well as in the West Bank, where 215 domestic dogs from seven districts were examined and the overall prevalence of leishmaniasis was 16.7% [
105]. Samples from 189 dogs, obtained in the town of Alfei Menashe, were analyzed and 3.3% of the animals tested positive for infection by
L. infantum [
106].
CVL in Turkey was first reported in 1951 in Istanbul and Bursa [
107] and, according to Toz et al. [
108], it is a common disease throughout the country, mainly caused by
L. infantum. Recently, in a study conducted by Koenhemsi et al. [
109] in Istanbul, 5/171 (2.92%) dogs of different breeds, ages, and tested positive for CVL. Infected dogs in Central Asia have been found in Kazakhstan, Turkmenistan, and Uzbekistan [
110].
The Indian subcontinent represents around 67% of the global VL load, where
L. donovani is the main etiological agent. Although VL there is still considered anthroponotic, there is evidence for the existence of a residual zoonotic reservoir, reinforced by the emergence of the disease in dogs and other canids [
99]. In India, the country most affected by VL in the world [
111], infected dogs have been identified in the state of Kerala [
112]. Nepal [
113] and Pakistan [
114] have also identified dogs infected with the parasite (
Table 1).
In Bangladesh, blood samples were collected by Alam et al. [
115] from 85 stray dogs in the Mymensingh district, with only 1.2% being positive for leishmaniasis. In contrast, Akter et al. [
99] obtained a 12% rate of seropositivity when evaluating 50 stray dogs in the same district. Recently, 20 dogs from the same district were examined and 20% were seropositive for
Leishmania infection [
116]. In all studies, the species detected was
L. donovani.
VL is a major public health issue in China, considered endemic or re-emerging in six provinces, including Xinjiang, Gansu, Sichuan, Shaanxi, Shanxi, and Inner Mongolia. Zoonotic VL is endemic, with dogs acting as the main reservoir of
L. infantum [
117,
118]. In 2022, Sandy et al. [
119] were the first to report the occurrence of CVL in Hong Kong. Dogs infected with
Leishmania have also been found in the Philippines and Vietnam [
120].
Europe
For many years, leishmaniasis has been the only tropical vector-borne disease endemic in southern Europe, where the majority of reported cases are due to zoonotic VL caused by
L. infantum [
121].
Among the Mediterranean Basin countries, Albania is one of the most affected by VL, and since the late 1980s, several
L. infantum isolates have been obtained from human and canine cases [
122]. In Bosnia and Herzegovina, domestic, stray, and shelter dogs from different parts of the country have been tested for leishmaniasis. In total, 16.7% of the animals tested positive, indicating that a significant part of the canine population was infected [
123].
The county of Split-Dalmatia in Croatia is considered an endemic area for CVL, with seroprevalence ranging from 0 to 42.8%. Dogs from the city of Split and 12 villages in the region were tested and 14.7% of the animals in Split were positive for
L. infantum infection, with eight villages having seroprevalence ranging from 7.1% to 42.8%, depending on its location [
124]. In another study conducted in 2008, the seroprevalence was 31% in Split-Dalmatia and 3.8% in Šibenik-Knin county [
125].
Cyprus, an island country located in the eastern Mediterranean region, has been without a reported case of CVL for over 20 years due to a decline in the number of sandflies and dogs. However, there has been an increase in the population of vectors and dogs, resulting in the resurgence of the disease in several areas in the south [
126,
127]. Infected dogs were also found in the island’s northern region with rates ranging from 1.9% to 13.2% [
128].
CVL is endemic in the south of the France, where several foci have been identified, such as Alpes-Maritimes, Cévennes, and Provence [
129,
130]. A seroprevalence of 29.6% was reported in Cévennes, according to study by Lachaud et al. [
131]. Dogs infected with
L. infantum were found in several French cities, including Toulon and Hyères in the department of Var, in addition to Miramas, Istres, and Salon-de-Provence, in the department of Bouches-du-Rhône, and Solenzara on the island of Corsica [
132]. Currently, through data obtained by veterinarians, it was possible to verify that the incidence of dogs infected by
L. infantum in a large part of French territory was between 0-5 cases/1,000 dogs/year. However, the number of cases in parts of south-eastern France reached 20 cases/1,000 dogs/year. Sporadic cases were reported in the north of the country, which is considered a non-endemic region for the disease [
133].
Between 2005 to 2010, samples from 5,772 dogs from different parts of Greece were collected, with an average reported seroprevalence of 22.09%. It was shown to vary from 6.5% in western Macedonia to 50.2% on the island of Corfu, and of the 43 prefectures from which the canine samples were collected, 41 had seropositive dogs, showing that the disease has been spreading [
134]. According to studies conducted by Symeonidou et al. [
135], it is possible to deduce that CVL remains a country-wide problem since seropositive dogs were found throughout the Greek departments, and most prefectures had at least one seropositive animal, with seropositivity rates ranging from 0% to 53%.
The main endemic areas for CVL in Italy include the central and southern regions and the islands of Sardinia and Sicily [
136], with seropositive animals identified in the regions of Abruzzo, Lazio, Tuscany, and Umbria in the center of the country; Apulia, Basilicata, Calabria, Campania, and Molise, in the south, as well as on the islands of Lampedusa, Sicilia, and Sardinia [
137,
138,
139,
140,
141,
142]. In recent decades, CVL has spread towards the north of the country, which had previously been considered a non-endemic area, with cases registered in Emilia-Romagna, Lombardia, Trentino-Alto Adige, Piedmont, and Vale D
’Aosta [
142,
143,
144,
145,
146]. Furthermore, the Republic of San Marino, an autonomous state located within Italian territory, presented a seroprevalence of 3.9% in 2012 [
147], making the entire Italian Peninsula an endemic area for the infection [
142].
In the Malta archipelago, 60 samples of dogs from different breeds were collected on the Islands of Malta and Gozo and 20% tested positive for leishmaniasis through molecular testing [
148].
In Portugal, according to Cardoso et al. [
149], dogs testing positive for
L. infantum are distributed throughout the mainland, namely the North, Centre, Alentejo, Lisbon, and Algarve. When analyzing 193 dogs living in kennels in the Algarve, Maia et al. [
150], found a general CVL seroprevalence of 16.06%. Furthermore, between 2011-2014, 170 dogs were studied in the same region and seroprevalence reached 18.2% [
151]. Schallig et al. [
152] showed that the number of seropositive dogs in Évora increased over a period of 20 years, with 9.4% in 1999 and 5.6% in 2010, as compared to 3.9% in 1990, the year of the initial study. In another study using 230 dogs from the district of Setúbal, Évora, Beja, and Faro, located in the south of the country, Maia et al
. [
153] obtained positive results for CVL, using qPCR, in 60.4% of the animals. In contrast, between 2011-2012, 581 dogs from five shelters in Lisbon and Setúbal were analyzed and 13.1% tested positive for
L. infantum [
154]. In a cross-sectional study by Almeida et al. [
155] using samples of 1,860 dogs from all parts of the country, the overall seroprevalence rate was 12.5%, with values ranging from 9.6% in the North to 17.2% in the Algarve.
CVL in Spain was considered restricted to the Mediterranean region. However, the disease has spread throughout most of the country, including the islands [
156]. The CVL seroprevalence rate varies from 2% to 57.1% between regions [
157] and these variations are related to environmental factors, geographic location, and vector dispersion [
158]. Northern Spain is considered a non-endemic area, with low seroprevalence [
157]. According to the results of a multicenter study by Diaz-Regañón et al. [
159], the highest seroprevalence obtained in the north was found in the commune of Aragon (24.56%) and the lowest in Asturias (1.27%). Through a cross-sectional serological survey conducted between 2011-2016, Galvéz et al. [
157], showed a high rate of seroprevalence in the southern Spanish provinces, such as Malaga (29.4%), Seville (25%), Murcia (23.7%), and the Balearic Islands (20%). In addition, for the first time, the seroprevalence of
L. infantum on the Canary Islands was reported for the first time with 2.45% of dogs testing also positive for leishmaniasis [
156].
Cases of CVL have been reported in other European countries, such as Bulgaria [
160], Georgia [
161,
162], Germany [
163], Hungary [
164], Kosovo [
165], The Netherlands [
163], North Macedonia [
166], Romania [
167,
168,
169,
170], Slovenia [
171], Switzerland [
163], and United Kingdom [
172] (
Table 1).
Table 1.
Percentage of CVL positive dogs and Leishmania species described in African, Asian, and European countries.
Table 1.
Percentage of CVL positive dogs and Leishmania species described in African, Asian, and European countries.
Continent |
Country |
Location |
Parasite species |
% of dogs positive for Leishmania (diagnostic test used) |
References |
África |
Ethiopia |
Amhara region |
L. donovani Complex* |
3.8% (RIFI and ELISA); 2.8% (PCR) |
[173] |
Kafta Humera district |
L. donovani |
27.7% (DAT); 14.8% (KDRT) |
[174] |
Amhara region |
L. donovani |
40% (DAT) |
[175] |
Addis Zemen, Humera, and Sheraro |
L. donovani Complex* |
5.9% (PCR) |
[176] |
Benishangul-Gumuz region |
NA |
13.9% (rK39 ICT); 5.6 (DAT) |
[177] |
Ambo, Ejaji, and Weliso |
L. infantum |
84.24% (ELISA) |
[178] |
Burkina-Faso |
Bobo-Dioulasso |
L. infantum |
5.88% (Serological test) |
[39] |
Côte d’Ivoire |
Abidjan and Yamoussoukro cities |
L. infantum |
8.9% (PCR or IFAT) |
[40] |
Nigeria |
Oyo, Ogun, and Kwara |
NA |
4.4% (ELISA) |
[41] |
Senegal |
Mont Rolland |
L. infantum |
46.3% (PCR) |
[42] |
Zambia |
Southern Province |
L. infantum |
NA (Serological tests and PCR) |
[43] |
Asia |
Iran |
Meshkin-Shahr district |
L. infantum |
15.8% (DAT) |
[179] |
|
Boyer Ahmad district |
L. infantum |
10% (DAT) |
[180] |
|
Kouhsar district |
L. infantum |
3.6% (DAT) |
[181] |
|
Khorasan Razavi province |
L. infantum |
7.6% (IFAT) |
[182] |
|
Kerman province |
L. infantum |
11.25% (DAT) |
[183] |
|
Kerman and Sistan-Baluchestan provinces |
L. infantum |
15.4% (ELISA) |
[184] |
|
Tehran and Alborz provinces |
L. infantum |
4.9% (DAT) |
[185] |
|
Meshkin-Shahr district |
L. infantum |
23.4% (DAT) |
[186] |
|
Hamedan province |
L. infantum |
3.95% (ELISA) |
[187] |
|
Jiroft district |
L. infantum |
7.9% (DAT) |
[188] |
|
Ardabil, Alborz, and East-Azerbaijan provinces |
L. infantum |
100% (DAT, rK39, and PCR) |
[102] |
|
Alborz province |
L. infantum |
2.97% (DAT) |
[189] |
|
Golestan province |
L. infantum |
18% (PCR) |
[190] |
Nepal |
Kathmandu |
L. donovani Complex* |
18.57% (PCR) |
[113] |
Pakistan |
Chilas, Abbotabad, Bagh, Poonch, and Muzafarabad districts |
L. donovani Complex* |
18% (DAT); 26.6% (ELISA) |
[114] |
Philippines |
NA |
L. infantum |
NA |
[120] |
Vietnam |
NA |
L. infantum |
NA |
[120] |
Europe |
Bulgaria |
Petrich |
L. infantum |
NA (IFAT, PCR) |
[160] |
Georgia |
Tbilisi and Kutaisi |
L. donovani Complex* |
20% (rK39 test) |
[161] |
Kvareli and Sagarejo districts |
19.5% and 11.4% (rK39 test) |
[162] |
Germany |
NA |
NA |
11.8% (ELISA) |
[163] |
Hungary |
Tolna province |
L. infantum |
30% (IFAT, PCR) |
[164] |
Kosovo |
Prizren, Gjakova, Rahovec, and Deçan |
L. infantum |
18.49% (ELISA) |
[165] |
The Netherlands |
NA |
NA |
32.4% (ELISA) |
[163] |
North Macedonia |
Skopje and Prilep |
L. infantum |
2.5% (PCR) |
[166] |
Romania |
Vâlcea County |
L. infantum |
NA (FASTest®LEISH) |
[167] |
Ramnicu Vâlcea |
L. infantum |
8.75% (ELISA);10% (PCR) |
[168] |
Galați |
NA |
8.33% (ELISA) |
[169] |
Argeș County |
L. infantum |
20.1% (PCR) |
[170] |
Slovenia |
Kostelo |
L. infantum |
NA (IFAT) |
[171] |
Switzerland |
NA |
NA |
12.2% (ELISA) |
[163] |
United Kingdom |
NA |
L. infantum |
NA (ELISA, PCR |
[172] |