Epidemiology; Disease transmission; Echinococcus multilocularis; Modelling; Echinococcosis; Diagnosis; Zoonoses; Echinococcus granulosus
Bebezov Bakhadyr, Mamashev Nurlan, Umetaliev Tilek, Ziadinov Iskender, Craig Philip S., Joekel Deborah E., Deplazes Peter, Grimm Felix, Torgerson Paul R. (2018), Intense Focus of Alveolar Echinococcosis, South Kyrgyzstan, in Emerging Infectious Diseases
, 24(6), 1119-1122.
PaternosterGiulia, BooGianluca, WangCraig, MinbaevaGulnara, UsubalievaJumagul, RaimkulovKursanbek, ZhoroevAbdykadyr, MüllhauptBeat, KronenbergPhilipp, FurrerReinhard, AbdykerimovKubanychbek, DeplazesPeter, TorgersonPaul, Epidemic cystic and alveolar echinococcosis in Kyrgyzstan—high resolution maps using national surveillance data identify disease hotspots, in Lancet Global health
Alveolar and cystic echinococcosis is caused by Echinococcus multilocularis and E. granulosus, respectively. Both diseases are considered to be neglected zoonoses. Despite this, they cause substantial burden of disease and are amongst the leading causes of foodborne parasitic diseases. Both diseases cause extensive human morbidity whilst alveolar echinococcosis (AE) is usually fatal if not treated . Whilst the extent of cystic echinococcosis (CE) is becoming more recognized, AE appears to be an emerging disease in many European countries including Switzerland. Outside of Europe in Kyrgyzstan there is now evidence for a major epidemic of AE with exponential increases in cases every year .Echinococcus spp. have complex life cycles where carnivore hosts play an important role in the transmission in Kyrgyzstan. Because of a poor functioning veterinary and sanitation system emerging zoonoses, diseases in humans which are transmissible by animals, are an increasing problem . Both The World Bank and the World Organization for Animal Health (OIE) have therefore advised to develop national animal disease control strategies (World Bank, 2011). However, the exact interplay between hosts is not fully understood and holds a crucial role in effective control. In addition, as Echinococcus poses a global threat, and is an emerging zoonotic disease in Switzerland, knowledge on the epidemiology and transmission is essential to protect public health. The high incidence of both AE and CE provides an opportunity to provide studies for epidemiological data that would be more difficult in Europe where the disease is presently rare in humans. The results of the proposed research will help understand the epidemiological situation and explore control strategies in a limited resource setting. It will also add to an understanding of infectious disease dynamics not only specifically applied to echinococcosis, but other transmissible parasitic diseases with complex life cycles and thus be of fundamental scientific importance. The proposal will also explore the natural history of the disease in a setting where community surveillance can identify early lesions and this will provide important information both from the modelling of the disease (ie the proportion of exposed infected individuals who could progress to clinical disease) and optimal clinical management of cases. Finally, it is hypothesized that the genotypes of E. multilocularis may be associated with clinical disease and this will be explored using isolates from Kyrgyzstan.This proposal aims to address the specific hypotheses:1. There are specific individual patient as well as transmission risk factors that are driving the human CE and AE epidemics2. Can the transmission dynamics of E. multilocularis from foxes and dogs to humans be adequately explained by mathematical modelling?3. Can an understanding of the risk factors for transmission and a model of the transmission dynamics be used to analyse and optimize different control strategies to reduce E. multilocularis and E. granulosus transmission and can such control strategies be undertaken in a cost effective manner?4. That a substantial number of humans exposed to E. multilocularis fail to develop AE based on diagnostic imaging and serology.5. Early surveillance strategies in humans (US, serology) contribute to an understanding of the transmission dynamics from canids to humans and to a cost-efficient management of AE by surgery of chemotherapy6. There are specific genotypes of Echinococcus associated with a high incidence of disease in Kyrgyzstan.We seek to answer address these hypotheses by analysing the spatial distribution of reported surgical cases of both E. granulosus and E multilocularis. Furthermore, we will develop a sophisticated mathematical model to simulate the transmission between the different hosts, building on the models already developed and used by the principal investigator. This model will be used to simulate the effect of proposed control strategies and enables us to calculate the cost-utility.Understanding the spatial distribution of the parasite in these definitive hosts and being able to model transmission and control will enable us not only to gain new insights in the transmission but also provide applicable knowledge on prevention strategies.An important parameter in our modelling strategy is to estimate the number of individuals exposed to E. multilocularis who develop clinical disease. It has been proposed that humans are relatively resistant to oncosphere invasion compared to other accidental hosts such as rats and furthermore, that a unknown proportion of liver infections are self-limiting based on serological studies and detection of calcified dead liver lesions but much more data have to be generated to support these hypotheses.