Phlebotomine sand flies (Diptera: Psychodidae) transmitting visceral leishmaniasis and their geographical distribution in China: a review.

After the existence of phlebotomine sand flies was first reported in China in 1910, the distribution of different species and their role in the transmission of visceral leishmaniasis (VL) have been extensively studied. Up until 2008, four species have been verified as vectors of VL, namely, Phlebotomus chinensis (Ph. sichuanensis), Ph. longiductus (Ph. chinensis longiductus), Ph. wui (Ph. major wui), and Ph. alexandri. The sand fly species vary greatly depending on the natural environments in the different geographic areas where they are endemic. Ph. chinensis is euryecious and adaptable to different ecologies, and is thus distributed widely in the plain, mountainous, and Loess Plateau regions north of the Yangtze River. Ph. longiductus is mainly distributed in ancient oasis areas south of Mt. Tianshan in the Xinjiang Uygur autonomous region. Ph. wui is the predominant species in deserts with Populus diversifolia and Tamarix vegetation in Xinjiang and the western part of the Inner Mongolia autonomous region. Finally, Ph. alexandri is steroecious and found only in stony desert areas, such as at the foot of the mountains in Xinjiang and the western Hexi Corridor, in Gansu province. This review summarized the relationship between the geographic distribution pattern of the four sand fly species and their geographical landscape in order to foster research on disease distribution and sand fly control planning. Furthermore, some problems that remained to be solved about vectors of VL in China were discussed.

[Diagnostic potential of five natural antigens from Echinococcus granulosus in the patients of cystic echinococcosis with different clinical status].

OBJECTIVE: To analyze the characteristics of serum antibody reactivity of cystic echinococcosis (CE) patients with different clinical status towards five native antigens obtained from Echinococcus granulosus (Eg). METHODS: The protoscolex somatic soluble antigen (EgPS), crude hydatid cyst fluid antigen (EgHF), partially purified hydatid fluid antigen (Burstein's antigen, EgBu), adult somatic soluble antigen (EgAs) and the native antigen B (EgAgB) were pre- pared. 369 serum samples from CE patients and 281 sera samples from healthy individuals were examined for the antibodies against 5 native antigens with indirect ELISA. The serologic results were classified according to clinical status, and the statistical analyses were carried out to understand the relationship between the results of different antigen-ELISA and the clinical status of patients. RESULTS: The results of EgBu, EgAS and EgAgB-ELISA showed that the antibody positive rate in hepatic CE patients [74.1% (212/286), 73.4% (210/286), 63.6% (182/286)] was significantly higher than that of other groups (including renal CE and pelvic CE, 1/8, 2/8, 1/8) (P < 0.05). Except EgAS, the S/N value of other groups examined by the rest four antigen-ELISA (EgPS: 3.10, EgHF: 2.40, EgBu: 1.60, EgAgB: 2.38) was also significantly lower than that of hepatic CE patients (3.73, 3.65, 4.40, and 3.61) (P < 0.05). EgBu, EgAS and EgAgB-ELISA results showed that the antibody positive rate in sera of recurrent CE patients [82.4% (150/182), 86.3% (157/182), 70.9% (129/182)] and the S/N value (5.54, 3.23, 3.75) were significantly higher than that of primary patients [positive rate: 67.4% (126/187); 63.6% (119/187); 57.2% (107/187); S/N value: 4.20, 2.70, 3.75] (P < 0.05). The S/N value detected by EgPS-ELISA and the positive rate examined by EgAgB-ELISA significantly increased with the increasing of the number of operations (P < 0.05), reached 4.23 and 91.7% (11/12), respectively, in the patients with > or = 4 times of operations. The positive rate and S/N value of EgAS-ELISA and EgAgB-ELISA increased with the number of hydatid cysts in patients (P < 0.05), reached 90.5% (19/21), 76.2% (16/21), and 3.97, 4.42, respectively, in patients with at least 4 cysts. Among the five antigen-ELISA, the positive rate increased with the cyst diameter (P > 0.05). The S/N value of EgHF-ELISA and EgAS-ELISA increased significantly with the cyst diameter (P < 0.05), reached 3.66 and 3.69, respectively, when the cyst diameter was > or = 15.1 cm. ROC analysis result showed that among the 5 native antigen-ELISA, the AUC(ROC) was highest in patients with cysts at CE2 stage (EgPS: 0.988 +/- 0.009, EgHF: 0.957 +/- 0.013, EgBu: 0.969 +/- 0.011, EgAs: 0.910 +/- 0.024, EgAgB: 0.894 +/- 0.021), EgAgB-ELISA presented the lowest AUC(RCO) of 0.267 +/- 0.031 in patients with cysts at CE5 stage. Except EgAgB, the positive rate of another 4 antigen-ELISA in detection of patients with cysts at CE 2 stage [EgPS: 97.2% (69/71), EgHF: 93.0% (66/71), EgBu: 88.7% (63/71), EgAs: 85.9% (61/71)] was slightly higher than that of the patients with cysts at CE1 stage, and then promptly reduced in patients with cysts at CE5 stage (EgPS: 56.3%, EgHF: 43.8%, EgBu: 12.5%, EgAs: 12.5%). In the patients with cysts at CE5 stage, the S/N value of the five antigen-ELISA was lowest (EgPS: 2.29, EgHF: 1.50, EgBu: 1.11, EgAs: 0.78, and EgAgB: 1.11). CONCLUSION: Compared with the other three antigens, the EgPS and EgAgB antigens have higher antigenicity, sensitivity, and specificity. The sera of hepatic CE patients are more reactive to the five native antigens than the other clinical types.

Genetic diversity of Leishmania donovani/infantum complex in China through microsatellite analysis.

The Leishmania strains from different epidemic areas in China were assessed for their genetic relationship. Twenty-nine strains of Leishmania infantum isolated from 1950 to 2001 were subjected to multilocus microsatellite typing (MLMT) using 14 highly polymorphic microsatellite markers. Twenty-two MLMT profiles were recognized among the 29 L. infantum strains, which differed from one another in 13 loci. Bayesian model-based and distance-based analysis of the data inferred two main populations in China. Sixteen strains belonged to one population, which also comprised previously characterized strains of L. infantum non-MON1 and Leishmania donovani. The parasites within this population are assignable to a distinct cluster that is clearly separable from the populations of L. donovani elsewhere, i.e. India, Sri Lanka and East Africa, and L. infantum non-MON1 from Europe. The remaining 13 Chinese strains grouped together with strains of L. infantum MON1 into another population, but formed a separate cluster which genetically differs from the populations of L. infantum MON1 from Europe, the Middle East, Central Asia and North Africa. The existence of distinct groups of L. infantum MON1 and non-MON1/L. donovani suggests that the extant parasites in China may have been restricted there, but not recently introduced from elsewhere.

Discovery and study of cutaneous leishmaniasis in Karamay of Xinjiang, West China.

Cutaneous leishmaniasis (CL) was discovered in the farms of the Karamay suburb, Xinjiang Uygur Autonomous Region in the 1990s. Between 1992 and 1994, a house-to-house survey revealed a prevalence of 1.0-1.6% in the residents. The clinical types of skin lesions included papule, plaque, ulcer and nodular prurigo. Observations verified that, in some cases, the skin lesions healed spontaneously in 10-14 months, whilst in other cases, they persisted for several years. Sporadic cases of CL have continued to appear at the dermatology clinic of the local hospital since 2000. Phlebotomus wui (Ph. wui), subgenus Larroussius was confirmed as the transmitting vector. The causative agent is Leishmania infantum sensu lato.

[Preliminary evaluation on the diagnostic performance of five native antigens from Echinococcus granulosus].

OBJECTIVE: To evaluate the diagnostic potential of 5 native antigens obtained from Echinococcus granulosus. METHODS: The cyst fluid and protoscoleces were collected from infected livers of slaughtered sheep near Urumqi. The protoscolex somatic soluble antigen (EgPS), crude hydatid cyst fluid antigen (EgHF), partially purified hydatid fluid antigen (Burstein's antigen, EgBu) and the native antigen B (EgAgB) were prepared. Echinococcus granulosus adult worms were collected from experimentally infected dogs, and then used to prepare adult somatic soluble antigen (EgAS). Serum samples from patients with cystic echinococcosis (369 cases), alveolar echinococcosis (14 cases), cysticercosis (20 cases), schistosomiasis (50 cases), paragonimiasis westermani (10 cases), visceral leishmaniasis (5 cases), and healthy individuals (366 cases) were examined for the antibodies against 5 native antigens with indirect ELISA. A ROC analysis was performed to determine a cut-off value for each native antigen. RESULTS: EgPS presented the highest AUC(BOC) (0.958 +/- 0.067), sensitivity (88.7%), positive predictive value (0.96), positive likelihood ratio (16.61), diagnostic efficiency (91.7%), and odds ratio (138.475). The specificity of EgBu (96.1%) was the highest, followed by EgAgB (95.7%), EgPS (94.7%), EgAS (89.0%), and EgHF (80.4%). The Youden index was ranked in order of EgPS>EgBu>EgHF>EgAS>EgAgB. The antibody reactive intensity of EgBu-ELISA was highest (4.055 +/- 1.365) and the EgAS-ELISA was lowest (2.947 +/- 1.276), and there was no significant difference between them (P > 0.05). The five native antigens presented high cross-reactivity with sera from alveolar echinococcosis (9/14-12/14) and from cysticercosis (8/20-16/20). CONCLUSION: There are significant differences among the five native antigen-ELISA. The EgPS antigen has the best diagnostic performance , which is followed by EgBu and EgAgB.

[Echinococcosis control in China: challenges and research needs].

Based on a review of the practices of echinococcosis control in China and of the historical experience from the international community in the field, this paper discussed the research achievements and challenges. The author indicated that it is a realistic time to launch a comprehensive control program in western China and there are urgent needs for scientific research integrating into the program.

Epidemiological evaluations of the efficacy of slow-released praziquantel-medicated bars for dogs in the prevention and control of cystic echinococcosis in man and animals.

To assess the epidemiological efficacy of type SRP III slow-released praziquantel-medicated bars for dogs in the prevention and control of cystic echinococcosis in man and livestock, praziquantel-medicated bars were implanted subcutaneously in over 90% of dogs in villages in north Xinjiang, China, where cystic echinococcosis is highly endemic. After implantation, infection rate of Echinococcus granulosus in dogs, specific antibodies in children and prevalence of echinococcosis in one-year-old lambs were observed for 3 years. Coproantigen of E. granulosus was positive in 41.2% of the dogs at the start of experiment. In the second and third year after medicated-bar implantation, coproantigen was undetectable in any dogs examined, while 3.0% of dogs were positive at the end of the fourth year. The antibody positive rate in 7-year-old pupils, that was 41.2% before the experiment, declined gradually and it was 5.4% in the fourth year, while children in the non-intervention control area showed 30.6% seropositivity. The prevalence of hydatid disease in children aged 7-16 years also declined significantly. The prevalence of hydatidosis in lambs one year of age was 44.8% in the first year, dropping to 10.7% in the fourth year, while in the non-intervention control area the level of infection was 46.4%. These results demonstrated not only that the slow released praziquantel-medicated bars efficiently blocked reinfection in dogs at least for 2 years, but also the measure was effective in preventing transmission of cystic echinococcosis to both man and livestock.

[Dynamic observation on ultrasonographic image during chemotherapy of hepatic cystic echinococcosis and a proposal for ultrasonic classification].

OBJECTIVE: To submit a proposal for the classification of ultrasonographic image in patients with hepatic cystic echinococcosis, on the basis of characteristic and distribution of ultrasonic image of hydatid cysts in cases and systematic observation on dynamic changes of sonographic image under treatment with emulsion albendazole and in relation to clinical efficacy. METHODS: The ultrasonic image of 645 cysts in 497 cases with liver cystic echinococcosis was classified. The distribution of different types of image in patients was analyzed. A comparative analysis of correspondence between the sonographic type and clinical efficacy was made in association with the rule of changes in ultrasonic features during chemotherapy. RESULTS: The ultrasonographic image of hydatid cysts was divided into six types. The distribution of ultrasonic types in patients reflected the process of natural evolution of cysts in human bodies. The dynamic change of ultrasonic image during treatment was identical with the natural evolution process of hydatid cysts. CONCLUSION: The proposal for ultrasonographic classification submitted reflects a long evolutionary process from growth to death of hydatid cysts in human body. The dynamic change of hydatid cysts during chemotherapy indicated that the effect of drug has accelerated this process. Therefore this classification may be applied in diagnosis and to judge the chemotherapeutic efficacy of cystic echinococcosis.