The prevalence of canine Leishmania infantum infection in western China detected by PCR and serological tests

Abstract

BackgroundCanine leishmaniasis (CanL) is endemic in western China, resulting in important public health problem. It is essential to evaluate the prevalence of canine Leishmania infantum infection for designing control policy. In the present study we report for the first time prevalence of Leishmania infection in dogs living in Jiuzhaigou County (Sichuan Provence, China), which is not only an important endemic area of CanL but also a tourism scenic spot, detected by PCR, ELISA and dipstick test. The results could provide key information for designing control programs against canine and human leishmaniasis. In addition, the complete sequence of the Leishmania isolate from Sichuan Province has not been reported to date and we present the sequences of 116 base-pair (bp) fragment of the conserved region in the minicircle kinetoplast DNA (kDNA) and the results of phylogenetic analyses based on the sequence of the amplified fragment.ResultsThe proportion of dogs infected with Leishmania in Jiuzhaigou County was 36.79%, 9.43%, and 51.88% detected by ELISA, dipstick test, and PCR, respectively. The ELISA and PCR tests were more sensitive than dipstick test. The PCR method is the most sensitive way to detect dogs infected with Leishmania parasites. The total positive rate for infected dogs in the area was 59.43% by the three methods. The PCR products of 116-bp fragment amplified from the kDNA conserved region of dog blood samples and laboratory maintained L. infantum were DNA sequenced and the variation of the sequences was observed. The phylogenetic tree based on the sequences of 116-bp fragment reveals that L. infantum is more genetically related to visceralizing species L. donovani than to the Leishmania species associated with cutaneous disease.ConclusionsMore than half of dogs living in the endemic Jiuzhaigou County were infected by L. infantum. Control measures, such as treatment or eradication of infected dogs, or prohibition of maintaining dogs, must be taken against these infected dogs due to their role in the transmission of the infection to vectors. The phylogenetic tree based on the sequences of conserved region in kDNA of Leishmania can effectively distinguish species of Leishmania.

Phylogenetic analysis of HSP70 and cyt b gene sequences for Chinese Leishmania isolates and ultrastructural characteristics of Chinese Leishmania sp.

“…Therefore, the two canine isolates and the other six Chinese isolates are suggested to be L. infantum in this study. Since the canine isolate WenChuan was from Sichuan, this result indicated that the canine leishmaniasis (CanL) in Sichuan may be caused by L. infantum, which is consistent with the recent studies (Shang et al 2011;Wang et al 2011). Moreover, considering the infected dogs are the main reservoir host of human VL, L. infantum should be the causative agents of VL in Sichuan province.…”

Molecular and Serological Evidence of Leishmania Infection in Stray Dogs from Visceral Leishmaniasis–Endemic Areas of Bangladesh

“…29,30 kDNA is considered the most sensitive target for leishmaniasis diagnosis, because it contains ∼10,000 minicircles per parasite. 31 Samples that were positive based on PCR and/ or real-time PCR, but negative based on rK39 ICT, might have a low infection burden and, therefore, lower levels of anti-Leishmania antibodies, consistent with previous studies 32,33 in which some seronegative dogs were PCR positive. In our study, we observed one serologically positive dog that was negative for Leishmania DNA.…”

Visceral Leishmaniasis in China: an Endemic Disease under Control

“…Based on extensive surveys from 1951 to 1959 (22), canine leishmaniasis of domestic dogs was reported in the adjacent regions of Beijing with landscapes similar to those in Liaoning, Hebei, Shandong, and other adjacent provinces in northeastern China (5-8, 21) ( Table 2). The rate of incidence in dogs expressed as percentage of infection was modest, but it was higher in the north, e.g., northern Hebei (19/146 ϭ 13%) and Liaoning (11/ 539 ϭ 2%), and very low in the south, e.g., Shandong (34/3,100 ϭ 0.1%) and southern Hebei (0/1,125 ϭ 0%) (18,19,22). In these regions, there has since been no report of either human VL or canine VL in domestic dogs.…”

“…The principal reservoirs are domestic dogs, which are thought to acquire infection originally from canids of the sylvatic cycle (16,17). Canine leishmaniasis has been reported at high rates in the western region, e.g., 59.43% (63/106) in Sichuan province and 77.21% (61/79) in Gansu province when surveyed in 2011 and 2006, respectively (18,19).…”