Monitoring and observing the trend distribution of intestinal parasitic infections in a certain community is precondition for planning and evaluation the existing intervention program. In line with this view, the present study attempted to assess a five year retrospective analysis of common intestinal parasites at Poly Health Center, Gondar, Northwest Ethiopia. The results of the study showed the occurrence of several intestinal parasites of public health importance among the community.
Although the present study used only wet mount technique that might have less sensitivity to diagnose light intestinal parasitic infections, the overall prevalence of intestinal parasite was 41.3% which was higher than other studies conducted in different part of Ethiopia; Bale-Robe (6.23%), Mojo Health Center (9.3%), Wonago Health center (16.6%) [21, 22, 23] and other countries’ report [24-35]. These differences in prevalence could be due to the use of different diagnostic methods and socio-demographic difference of the study subjects or it might be due to a reflection of the local endemicity and geographic condition of the study area.
Entameaba histolytica/dispar (40.7%) was the most prevalent intestinal parasite but it was lower than the previous study in Wonago Health center (53.8%) in Ethiopia . However, the prevalence in the present study was higher than that of the studies done in Bale- Robe (26.3%)  and other countries, Palestine (16.3%) , Palajunoj Valley of Guatemala (16.1%) , Osmangazi University Medical Faculty in Turkey (31%)  and Kenitra in Morocco (23.7%) . The prevalence of this study was also significantly higher than the studies conducted in Mojo Health Center (4.0%) in Ethiopia , Uludag University Medical School Hospital (5.4%), Istambul (0.05%), Tokat public Laboratory (0.8%), Dukuz Eylul University Medical Faculty Hospital (0.3%), Sivas municipality (3.7%) in Turkey, Riyadh Region (0.14%) in Saudi Arabia and Tehran (1.1%) in Iran [25-28, 30-32]. These differences might be due to the difference in diagnostic methods as discussed earlier. In addition, might be due to the difference in getting safe drinking water.
In the present study, Giardia lambilia (27.5%) was the second most prevalent intestinal parasite and Ascaris lumbricoides (16.2%) as the leading helminthic parasite followed by N. nana, Hook worm, E. vermicularis, S. mansoni, with the prevalence of 4.1%, 3.3%, 2.4%, 2.4%, respectively and the least prevalence Taenia species (0.7%) which was differ from the studies done in Ethiopia [21, 22, 23] and others countries [24, 25-32, 35]. In addition to the possible factors like difference in diagnostic approach and the sources of safe drinking water discussed earlier, the differences in the proportions of these parasites in different studies might be also due to the difference in socio‐economic level, sanitary/hygienic status, occupation and cultural activities and nutritional factors of the study populations.
The result of our study revealed that, a slight fluctuating overall trend of intestinal parasitic infection was observed in the study area. A decreasing number of infection occurred in 2010 comparing with reported in 2009. However, there was a gradual increment of number of cases from 2011 to 2013 with higher intestinal parasite infection being reported in 2013. Similar studies in Ethiopia , Palestine , Turkey  and Saudi Arabia  reported fluctuating trend of overall intestinal parasite infection. However, our study finding was differs from the study conducted in Ethiopia  and Turkey  which was increasing and Turkey , Italy  and Morocco  which was decreasing trend parasite infection. The possible reason might be due to the difference prevention control strategy of different locality in a country and between countries, geographical difference, and the living condition of the study subjects. In the present study area, there is no prevention and control strategy except treating patients suspected and diagnosed for intestinal parasitic infections.
Out of the total data review in the last five year in the health center, males and females were equally affected for intestinal parasites infection except Hookworm and Shistosoma mansoni. Males were more affected than females by Hookworm and Shistosoma mansoni. This study is consistent with the study done in Uludag University Medical School Hospital and Istanbul in Turkey [25, 26]. But in other studies in Mojo Health Center and Monago Health Center in Ethiopia [22, 23], Tokat Public laboratory, Osmangazi University Medical Faculty in Turkey [27, 29], females were more affected. The differences in the proportion of parasitic infection between males and females might be due to the difference in their daily activities. In the study area, males are mostly involved in outdoor activities like farming and swimming. This activities might more exposed males to the soil transmitted parasitic infection and intestinal flukes.
Regarding to the age groups, 20 –29 years were highly affected groups, with a prevalence rate of (26.5%), followed by < 9 year olds (24.9%). Entamoeba histolytica/dispar (28.4%), Hookworm (30.1%), and Strongloide stercularis (32.0%) was higher in the 20–29 age groups. Giardia lamblia (30.3%), Hymenolepis nana (46.1%), Enterobius vermicularis (30.8%) and Trichuris trichuria (34.0%) were higher in the age groups of < 9 years. The 10–19 age groups were also affected by Ascaris lumbricoide, Shistosoma mansoni and Taenia species. The higher overall distribution of Entamoeba histolytica/dispar, Hookworm, and Strongloide stercularis in adolescence groups in the present study was in agreement with other studies in Ethiopia [21, 22] and in other countries [25, 26, 28, 34]. But it was differ from other study done in Wonago health center in Ethiopia and Catholic University Hospital in Italy [23, 33]. This may be probably due to the difference of hygienic status. The highest infection was in the childhood, adolescent and oldest group. These indicate that these groups of persons are highly active and they are less likely to keep their hygiene. They might have close contact with pollutant with soil or water bodies to play.