Humans can acquire hydatid disease by ingesting parasite eggs defecated by a final host. The embryos hatch from the eggs in the intestinal tract and penetrate the duodenal mucosa, then enter the portal circulation and disseminate throughout the body (Iuliano et al. 2000).
The present study showed the distribution of hydatid cyst infections according to year was higher in the year 2013 (36.1%) than in other years; 2014 (29.5%), 2015 (26.2%) and 2016 (8.2%) respectively (Fig. 2). No significant differences between the years with HD infection (Table 1).
Table 1
Distribution of hydatid cysts according to locations of Baghdad city
| Location | Count (%) |
| Al-Resafa | 3 (4.9) |
| Baghdad Al-Jedida | 12 (19.7) |
| Baladiat | 9 (14.8) |
| Sadder city | 19 (31.1) |
| Madain | 9 (14.8) |
| Shaab | 7 (11.5) |
| Abu Ghraib | 1 (1.6) |
| Adhamiya | 1 (1.6) |
| Total | 61 (100) |
| p-value | 0.266 (P > 0.01) |
This could be due to an increase in the population of final hosts (stray dogs) and decreased public awareness on the disease's transmission (Gessese 2020).
Also, the results showed that the percentage of parasite infection in females (57%) is higher than in males (43%) (Fig. 3).
Females are more susceptible than males to echinococcosis could be due to differences in physiological and hormonal factors. Previously, an experimental study on BALB/c mice found that gender can act as a factor of susceptibility to infection by echinococcosis (Blancas Mosqueda et al. 2007).
It was observed that Sadder City (31.1%) was more risk of hydatid cyst infections than other Baghdad sectors; Baghdad Aljedida (19.7%), Al-Baladiat (14.8%), Al-Mada’in (14.8%), Al-Sha’ab (11.5%), Al-Rusafa (4.9%), Abu Ghraib (1.6%), Adhamiya (1.6%) respectively (Fig. 4 &5). No significant differences among sectors of Baghdad city (p > 0.01) of hydratid cyst infection (Table 1).
In sectors relationship with the disease, 19 (31.1%) of people living in Sadder City is at high risk of infection of hydatid (Table 1).
The Sadder City has the potential for a high percentage of echinococcosis due to the existence of domestic animal husbandry jobs and many stray dogs. Also, there is insufficient knowledge about this disease in this sector. Dogs and domestic animals have a role in maintaining the life cycle of E. granulosus not only in rural areas but also in city regions (Aziz et al 2022; Murtaza et al 2017). The highest prevalence of echinococcosis was observed in Sadder City because, the greatest possibility of contact with infectious sources such as soil, dogs, and raw vegetables (Rokni 2009).
In addition, the study found that the female infection rate with HD was 57.4% while the male infection rate was 24.6%. No significant differences between male and female with HD infection (Table 2).
Table 2
Distribution of hydatid cysts according to gender
| Group | Gender | Total |
| Count (%) | Male | Female |
| 26 (24.6) | 35 (57.4) | 61 (100) |
| p-value | 0.617 (p > 0.01) | |
Also, this study found the most susceptible age group to this parasite was 15-45y (73.8%) than other age groups: 5-14y (6.6%) and > 46y (19.7%) as shown in (Fig. 6). No significant differences between age groups with HD infection rate (Table 3).
Table 3
Distribution of hydatid cysts according to age group
| Age group | Count (%) |
| 1–4 y | 0 (0) | |
| 5–14 y | 4 (6.6) | |
| 15–45 y | 45 (73.7) | |
| > 45 y | 12 (19.7) | |
| Total | 61 (100) | |
| p-value | 0.766 (p > 0.01) ** |
Table 4
Distribution of hydatid cysts according to years
| Year group | Count (%) |
| 2013 | 22 (36.1) |
| 2014 | 18 (29.5) |
| 2015 | 16 (26.2) |
| 2016 | 5 (8.2) |
| Total | 61 (100) |
| p-value | 0.990 (p < 0.01) |
Similar results have been reported from previous studies (Ahmadi and Badi 2011; Chalechale et al. 2016; Sarkari et al. 2010). Echinococcosis is a chronic disease with an incubation period of between 20 and 30 years, and the cyst grows more slowly in humans than in animals. This reason explains the high rate of infections in people in the age group of 21–40 years old (Ahmadi and Badi 2011).
About distribution of HD according to the years, it was found that the year 2013 recorded highest percent of infection (36.1%).