Sonographical and Serological Survey of Human Cystic Echinococcosis and Analysis of Risk Factors Associated with Seroconversion in Rural Communities of Kerman, Iran

Abstract

Cystic echinococcosis (CE) caused by larval stage of Echinococcus granulosus, is an endemic zoonosis in Iran particularly in rural regions. The objective of this study was to determine the prevalence of CE among rural communities in Kerman using ultrasonography (US) and serology. Kerman Province, in southeastern Iran, is the largest province, with 2.9 million inhabitants. A sample of 1140 individuals (200 males and 940 females) was selected by randomized cluster sampling in 2006-2008. After acquiring informed consent for each participant a questionnaire was filled, complete abdominal US in supine position was carried out and 5 ml blood was collected for ELISA test. Two hydatid cases (0.2%) were detected by ultrasound. Serological results showed 7.3% seropositivity, and females (8.3%) were significantly more positive than males (2.1%). There were significant difference between CE seropositivity and sex, age and occupation. Residents of desert regions (Shahdad, Andouhjerd and Golbaf) were 2.5 times more likely to be seropositive than mountainous regions with better socioeconomic status (OR = 2.5; 95% CI = 1.09-5.95). Dog ownership does not appear to be a significant risk factor for CE in the region. Only about 10% of households own dogs, usually only one dog. However, the stray dog population of Kerman province is estimated at 145 000-480 000 (3.5-11.5 times the owned dog population). Infection in humans and animals would appear to come mostly from infected stray dogs. Management of stray dog population could make major progress in control of hydatid disease. In addition, proper washing of vegetables decreased probability of infection by 53% (OR = 0.47; 95% CI = 0.26-0.84). The serological study showed that many people, especially women, had been exposed to Echinococcus eggs and had seroconverted but were not infected.

Diagnostics in cystic echinococcosis: Serology versus ultrasonography

“…False-positive serological results may also be returned in non-active disease stages, during pregnancy, and in patients with autoimmune or malignant diseases (34). Finally, women seem to be more frequently affected by E. granulosus infections (38).…”

Global Distribution of Alveolar and Cystic Echinococcosis

“…Source of domestic water was described as a significant risk factor for human CE in Jordan (Dowling et al, 2000). It has been suggested that in Muslim countries dog ownership is not a major risk factor for human infection because the major risk in these countries arises from high levels of environmental contamination with dog faeces due to high numbers of stray dogs (Dowling et al, 2000;Harandi et al, 2011). In the case of Syria, current prevalence data regarding human infection are not available and detailed epidemiological studies are required from this country.…”

“…The parasite circulates primarily among domestic dogs (owned and stray animals) as definitive hosts and a variety of domestic livestock as intermediate hosts (Dowling et al, 2000;Harandi et al, 2011;Rafiei et al, 2007;Shariatzadeh et al, 2015). However, a wild animal cycle has been documented in Iran and Turkey involving wolf, jackal, hyena and red fox as definitive hosts, and wild sheep (Ovis orientalis) and the goitered gazelle (Gazella subgutturosa) as intermediate hosts (Dalimi et al, 2002(Dalimi et al, , 2006Eslami et al, 1981Eslami et al, , 2016Simsek and Eroksuz, 2009).…”

“…communities and the absence of pig farming due to religious beliefs (Dakkak, 2010;Dar and Alkarmi, 1997;Harandi et al, 2011;Rokni, 2009). Table 10 summarizes the occurrence of Echinococcus species and genotypes causing CE in the ME.…”

Cystic echinococcosis is an occupational disease?

“…The highest rate of infection was found in 40-60 year old age group with 1.8 % and the least rate was in 20-40 year old age group as 0 %. In Golestan (North of Iran) and Kerman (Southeast) Provinces, the highest rates of the disease were observed in 30-60 and 20-30 year old age groups, respectively (Harandi et al 2011;Baharsefat et al 2007). In fact, hydatidosis is considered as a chronic disease of long incubation period (might be 20-30 year) and accordingly a wide range of different ages is noticeable in infected individuals (Torgerson and Deplazes 2009).…”