Ultrasound-Based Prevalence of Cystic Echinococcosis in the Samarkand Region of Uzbekistan: Results from a Field Survey

Cystic echinococcosis (CE) is a zoonosis caused by Echinococcus granulosus. Uzbekistan is endemic for CE, but estimates of disease burden are lacking. We present findings from a cross-sectional, ultrasound-based survey evaluating the prevalence of human CE in the Samarkand region, Uzbekistan. The survey was conducted between September and October 2019 in the Payariq district, Samarkand. Study villages were selected based on sheep breeding and reported human CE. Residents aged 5-90 years were invited to receive a free abdominal ultrasound examination. The WHO Informal Working Group on Echinococcosis classification was used for cyst staging. Information regarding CE diagnosis and treatment was collected. Of 2,057 screened subjects, 498 (24.2%) were male. Twelve (0.58%) had detectable abdominal CE cysts. In total, five active/transitional (N = 1 CE1, N = 1 CE2, N = 3 CE3b) and 10 inactive cysts (N = 8 CE4, N = 2 CE5) were identified. Two participants had cystic lesions with no pathognomonic features of CE and were given a 1-month course of albendazole for diagnostic purposes. Twenty-three additional individuals reported previous surgery for CE in the liver (65.2%), lungs (21.6%), spleen (4.4%), liver and lungs (4.4%), and brain (4.4%). Our findings confirm the presence of CE in the Samarkand region, Uzbekistan. Additional studies are needed to assess the burden of human CE in the country. All patients with a history of CE reported surgery, even though most cysts found during the current study were inactive. Therefore, it appears there is a lack of awareness by the local medical community of the currently accepted stage-specific management of CE.

Burden of disease in Gabon caused by loiasis: a cross-sectional survey

BACKGROUND

Loiasis is a highly prevalent helminth infection found in distinct regions of sub-Saharan Africa. The disease has been considered to be of minor clinical significance, but this belief is being increasingly challenged by recent evidence. We aimed to prospectively quantify the overall burden of disease caused by loiasis in an endemic region of Gabon, using disability-adjusted life years (DALYs).

METHODS

We did a cross-sectional survey during 2017 and 2018 in rural Gabon. Volunteers underwent diagnostic tests for loiasis and were given a standardised questionnaire on symptoms. Participants reporting eye worm migration or harbouring Loa loa microfilariae were defined as loiasis positive. Morbidity-based DALYs associated with loiasis were estimated for the rural population of Gabon.

FINDINGS

Between Sept 1, 2017 and May 31, 2018, 1235 participants residing in 38 villages in the Gabonese departments of Tsamba-Magotsi and Ogooué et des Lacs were screened. 626 (50·8%) of 1232 eligible participants had loiasis. 520 (42·2%) of 1232 participants reported eye worm migration. 478 (93·9%) of 509 individuals with eye worm migration also reported associated pain, and 397 (78·6%) of 505 reported vision disturbances. After correcting for age and sex, loiasis was significantly associated with a variety of symptoms, including transient painful oedema (adjusted odds ratio 1·76 [95% CI 1·37-2·26]) and arthralgia (1·30 [1·01-1·69]). Application of attributable fractions of correlating symptoms resulted in 412·9 (95% CI 273·9-567·7) morbidity-based DALYs per 100 000 people in rural Gabon.

INTERPRETATION

Loiasis, with the pathognomonic sign of eye worm migration, appears to not be benign, but severely impeding to affected individuals. Furthermore, loiasis is associated with substantial morbidity, comparable to that of other neglected tropical parasitic diseases. These findings call for reconsideration of L loa as a relevant pathogen in affected populations, with a need for more concerted research and control of these infections.

FUNDING

Federal Ministry of Science, Research and Economy of Austria, and the European Union.

PO 8382 CLINICAL AND LABORATORY ASSESSMENT OF LOA LOA INFECTIONS IN GABON

Background

Loiasis is a parasitic infection highly endemic in West and Central Africa. Previously often considered as a benign infection, recent studies have suggested that high microfilaria loads in loiasis patients may be associated with increased mortality. The true impact of loiasis on affected communities is unknown. Reports on clinical symptoms and changes in laboratory values due to loiasis infection are focused mostly on returning travellers. Assessments in endemic populations have scarcely been performed. Laboratory alterations such as eosinophilia are thought to be present mostly in patients from non-endemic areas.

Methods

This cross-sectional study was performed in rural Gabon to investigate the clinical symptoms and laboratory changes caused by loiasis in an endemic population. Inclusion criteria were local residency for at least two years and an age above two years. Participants were interviewed with a questionnaire covering loiasis-specific symptoms, exploratory questions and history of eye worm. Local vocabulary was employed if needed. At the same time L. loa microfilaria diagnostics were performed including thick blood smear preparation and concentration techniques. Additionally, differential blood count and haemoglobin measurements were performed. Peripheral blood withdrawals were done between 10 am and 3 pm.

Results

A total of 1030 participants were recruited, of whom 56% were female; they were between 2 and 98 years of age. L. loa microfilariae were detectable in 27% of all participants. Microfilariae densities ranged from 1 to 76 250 Mf/mL. Overall a positive history of eye worm was reported in 56%, with 25% of participants reporting eye worm passage and 36% Calabar swelling within the last year. Also, an analysis of laboratory parameters in comparison to clinical data and infection status was performed.

Conclusion

Loiasis infection should receive more attention by the scientific community and further studies are needed, as the disease causes substantial morbidity in endemic populations.

The Echinococcoses: Diagnosis, Clinical Management and Burden of Disease

The echinococcoses are chronic, parasitic diseases that are acquired after ingestion of infective taeniid tapeworm eggs from certain species of the genus Echinococcus. Cystic echinococcosis (CE) occurs worldwide, whereas, alveolar echinococcosis (AE) is restricted to the northern hemisphere, and neotropical echinococcosis (NE) has only been identified in Central and South America. Clinical manifestations and disease courses vary profoundly for the different species of Echinococcus. CE presents as small to large cysts, and has commonly been referred to as 'hydatid disease', or 'hydatidosis'. A structured stage-specific approach to CE management, based on the World Health Organization (WHO) ultrasound classification of liver cysts, is now recommended. Management options include percutaneous sterilization techniques, surgery, drug treatment, a 'watch-and-wait' approach or combinations thereof. In contrast, clinical manifestations associated with AE resemble those of a 'malignant', silently-progressing liver disease, with local tissue infiltration and metastases. Structured care is important for AE management and includes WHO staging, drug therapy and long-term follow-up for at least a decade. NE presents as polycystic or unicystic disease. Clinical characteristics resemble those of AE, and management needs to be structured accordingly. However, to date, only a few hundreds of cases have been reported in the literature. The echinococcoses are often expensive and complicated to treat, and prospective clinical studies are needed to better inform case management decisions.

Echinococcus multilocularis in North America: the great unknown

Over the last decade, studies have begun to shed light on the distribution and genetic characterization of Echinococcus multilocularis, the causative agent of alveolar echinococcosis (AE), in North America. Recent findings indicate that the parasite is likely expanding its range in the central region of the United States and Canada and that invasions of European strains might have occurred. In our review, we present the available data on E. multilocularis infections in wild and domestic animals and humans in North America and emphasize the lack of knowledge on the distribution of the parasite in wild and domestic hosts. Furthermore, we stress the need to better understand the complexity of host communities and their roles in shaping the transmission and distribution of the parasite. We hypothesize that a lack of knowledge about AE by North American physicians might result in the misdiagnosis of cases and an underestimation of disease incidence. The endemic presence of the parasite in urban areas and a recent human case in Alberta, Canada, suggest that the scientific community may need to reconsider the local public health risks, re-assess past cases that might have been overlooked and increase surveillance efforts to identify new cases of human AE.

A questionnaire-based evaluation of the veterinary cordon fence separating wildlife and livestock along the boundary of the Kruger National Park, South Africa

Veterinary cordon fences are used in Southern Africa to separate wildlife from domestic animals in order to prevent transmission of infectious diseases. Such fences are a control method recognized by the World Organization for Animal Health (OIE) for establishing disease-free zones in beef exporting countries. However, few studies have evaluated the ecological impact of these physical barriers or their effectiveness at a multispecies level. We examined the permeability of one such barrier, along 357 km of the western and southern boundary of the Kruger National Park (KNP) during 2007. Information was gathered using a semi-structured questionnaire implemented among 32 teams of fence maintenance workers. Data were analyzed to identify (a) the main causes of fence damage, (b) the seasonality, location and duration of fence repairs, (c) high permeability areas for elephant (Loxodonta africana), kudu (Tragelaphus strepsiceros), impala (Aepyceros melampus), buffalo (Syncerus caffer) and warthog (Phacochoerus africanus), and (d) the influence of fence electrification, rivers and elephant damage on the frequency of observation of wildlife species outside the KNP estimated during the year. Human and elephant damage were the most common reasons for fence repairs. Elephant and buffalo were the most and least common large mammal species reported observed outside the KNP (1076 and 162 reports/year), respectively. Cattle incursions into the KNP were also reported in 44% of the fence sections. Electrification of the fence was an important factor explaining differences in estimated wildlife species observations outside the KNP during the year. Correlations between estimations of observed species suggested that fence gaps created by elephants might be used by the other wildlife species. Estimated annual counts of kudu, impala and buffalo, but not warthog, were found to correlate with elephant observations. Negative binomial regression models were developed to explore the relationships between observed estimations of different wildlife species outside the KNP the fence, electrification of fence sections and the presence of watercourses, suggesting that kudu, impala and buffalo could use elephant induced fence damage to leave the KNP. The questionnaire was able to evaluate fence integrity and identify sections where integrity was sub-optimal for separating wildlife from domestic livestock species. If combined with more quantitative methods and applied on a routine basis, it could provide an efficient and cost-effective method for monitoring the effectiveness of physical barriers to contain wildlife within protected areas such as is the case with veterinary cordon fences in Southern Africa.

Grass height and transmission ecology of Echinococcus multilocularis in Tibetan communities, China

BACKGROUND

Alveolar echinococcosis is a major zoonosis of public health significance in western China. Overgrazing was recently assumed as a potential risk factor for transmission of alveolar echinococcosis. The research was designed to further test the overgrazing hypothesis by investigating how overgrazing influenced the burrow density of intermediate host small mammals and how the burrow density of small mammals was associated with dog Echinococcus multilocularis infection.

METHODS

The study sites were chosen by previous studies which found areas where the alveolar echinococcosis was prevalent. The data, including grass height, burrow density of intermediate host small mammals, dog and fox fecal samples as well as Global Positioning System (GPS) position, were collected from field investigations in Shiqu County, Sichuan Province, China. The fecal samples were analyzed using copro-PCR. The worms, teeth, bones and hairs in the fecal samples were visually examined. Single factor and multifactor analyses tools including chi square and generalized linear models were applied to these data.

RESULTS

By using grass height as a proxy of grazing pressure in the homogenous pasture, this study found that taller grass in the pasture led to lower small mammals' burrow density (chi(2) = 4.670, P = 0.031, coefficient = -1.570). The Echinococcus multilocularis worm burden in dogs was statistically significantly related to the maximum density of the intermediate host Ochotona spp. (chi(2) = 5.250, P = 0.022, coefficient = 0.028). The prevalence in owned dogs was positively correlated to the number of stray dogs seen within a 200 meter radius (Wald chi(2) = 8.375, P = 0.004, odds ratio = 1.198).

CONCLUSIONS

Our findings support the hypothesis that overgrazing promotes transmission of alveolar echinococcosis and confirm the role of stray dogs in the transmission of alveolar echinococcosis.

Impact of overgrazing on the transmission of Echinococcus multilocularis in Tibetan pastoral communities of Sichuan Province, China

BACKGROUND

Overgrazing was assumed to increase the population density of small mammals that are the intermediate hosts of Echinococcus multilocularis, the pathogen of alveolar echinococcosis in the Qinghai Tibet Plateau. This research tested the hypothesis that overgrazing might promote Echinococcus multilocularis transmission through increasing populations of small mammal, intermediate hosts in Tibetan pastoral communities.

METHODS

Grazing practices, small mammal indices and dog Echinococcus multilocularis infection data were collected to analyze the relation between overgrazing and Echinococcus multilocularis transmission using nonparametric tests and multiple stepwise logistic regression.

RESULTS

In the investigated area, raising livestock was a key industry. The communal pastures existed and the available forage was deficient for grazing. Open (common) pastures were overgrazed and had higher burrow density of small mammals compared with neighboring fenced (private) pastures; this high overgrazing pressure on the open pastures measured by neighboring fenced area led to higher burrow density of small mammals in open pastures. The median burrow density of small mammals in open pastures was independently associated with nearby canine Echinococcus multilocularis infection (P = 0.003, OR = 1.048).

CONCLUSION

Overgrazing may promote the transmission of Echinococcus multilocularis through increasing the population density of small mammals.