Abstract
The objective of the current study was to determine the incidence of common types of parasites encountered in the Central Region of Saudi Arabia. The current study is a retrospective study which includes the results of 10427 stool sample and occult blood sample. The results obtained during last two years (2005–2007), were compared to the earlier reports on parasites in the Central as well as other regions of Saudi Arabia. Attempts were made to find out the cases of increasing and/or decreasing trend of parasite incidence and to locate any differences between the current study results and the earlier reports.
Key words: Intestinal parasites, Stool, Blood, Riyadh region, Saudi Arabia
1. Introduction
Stool analysis is a common laboratory test used to screen for parasites in cases of diarrhea and other gastrointestinal disorders. Sometimes the test is used to confirm the presence of a specific parasites related to a specific clinical situation like the Schistosoma parasite in cases of hepatosplenomegaly or hook worm parasite in case of iron deficiency anaemia (WHO, 1991; Kochhar, 2004; Halton et al., 2005). The parasites seen in a stool specimen usually include either: Protozoa trophozoites and/or cysts. Complete worms or segments of a Taenia worm can also be seen (Cox, 1993; Panjarathinam, 2007). However, in cases of Strongloides stercoralis worms ova or larvae are known to be present (Iqbal, 2008). Stool sample can also be examined for occult blood especially to confirm or exclude more serious gastrointestinal problems like duodenal or gastric ulcers or gastrointestinal malignancies.
A report on stool analysis of male immigrant manual workers in Saudi Arabia, suggested that nine out of ten patients suffered from human fascioliasis (Haseeb et al., 2002; Sanad and Al-Megrin, 2005). However, fascioliasis, caused by Fasciola species, is actually a disease of herbivorous animals and occasionally found in human (Haseeb et al., 2002). All patients of fascioliasis presented established clinical features and showed anaemia and eosinophilia. Several studies conducted on stool smear stained with eosin, iodine and Zehl-Nelson stains, further showed the presence of Entamoeba histolytica, Entamoeba coli, Giardia lamblia and Cryptosporidium parvum (Abdel-Hafez et al., 1986; Zakai, 2004; El-Mathal and Fouad, 2005). Abdominal pain and pruritus ani were the most common causes of referral in the patient group and G. Lamblia was found to be among the most common pathogenic parasite (Ahmed and El-Hady, 1989).
In young male and female students of Riyadh region (Saudi Arabia) different other intestinal parasites were found including: Ascaris lumbricoides, Trichuris trichiura, Schistosoma mansoni, Hymeolepis nana, Ancylostoma duodenale, Enterobius vermicularis, Taenia saginata and Schistosoma hematotium (Abdel-Hafez et al., 1986).
In the present study, the prevalence of common types of intestinal parasites encountered in Riyadh region was determined. The results were compared with earlier reports from the same region and other regions of Saudi Arabia to observe any current changes in the pattern of parasitic intestinal infection, in Riyadh.
2. Materials and methods
A total of 10,427 samples received during the period 10/2/2005–16/1/2007 in the Department of Parasitology, Central Laboratory, King Saud Medical Complex (KSMC), Ministry of Health (M.O.H.), Riyadh were included in the current study. The sample specimens were mainly received from Riyadh Medical Complex which is a 1500 bedded tertiary care hospital. Other specimens received were from Riyadh Medical Health Centres, M.O.H, and samples of the food handlers taken during pre-employment medical check up by Riyadh Municipality. However, Riyadh Municipality specimens were sent for reference and confirmation of the findings of their own laboratory results. The sources and number of the specimens received is shown in Table 1. Some of the specimens were rejected and not examined due to certain reasons and the details about such samples are given in Table 2.
Table 1.
The sources, number and percent of the specimens received.
| Sources of the specimens received | Number and percent of the specimens |
|---|---|
| Riyadh Central Laboratory Collection Room (CR) | 8621 (82.68%) |
| King Saud Medical Complex | 1153 (11.06%) |
| Riyadh Central Laboratory | 417 (4.00%) |
| Riyadh Municipality Laboratory | 104 (1.00%) |
| Other sourcesa | 132 (1.27%) |
| Total | 10,427 (100%) |
Including Health Care and Rehabilitation Centres.
Table 2.
The number of stool sample rejected and the reasons for rejections.
| Reason for rejection | Number rejected |
|---|---|
| No laboratory number on the container label | 1 (2.70%) |
| No sample in the container (empty container) | 5 (13.51%) |
| Request form received without a sample | 21 (56.76%) |
| Contaminated samples | 1 (2.70%) |
| The laboratory number on the container and request form are not the same | 2 (5.41%) |
| Two samples received with the same laboratory number | 2 (5.41%) |
| Wrong sample urine was received instead of stool | 5 (13.51%) |
| Total | 37 (100%) |
The analysis of all the samples was carried out by following the World Health Organization protocol for physical and microscopic examination with minor modifications (WHO, 1991, 2004). Faecal smears are prepared in saline, eosin and iodine and examined directly. In special cases including the specimens from Riyadh Municipality Laboratory, a formol saline concentration was used prior to microscopic examination. Occult blood was tested by following the instructions and procedures given by the manufacturers as shown in the inserted leaflet of whatever available kit. All records were maintained in a local computer system. The results were analyzed by using Microsoft Excel and Access programmes together with SPPS version 13.0. on personal computer.
3. Results
A total of 37 specimens out of 10,427 stool specimens received were rejected mainly due to mistakes including improper sampling, contaminations, wrong labels, and wrong numbering (Table 2). The results of the parasitological analysis of the specimens received are depicted in (Table 3).
Table 3.
The results of the parasitological analysis of the specimens received.
| The Parasite identified | Number |
|---|---|
| Entamoeba coli | 403 (4.08%) |
| Iodamoeb buetschlii | 177 (1.79%) |
| Indolimax nana | 173 (1.75%) |
| Ascaris | 66 (0.67%) |
| Giardia lamblia | 66 (0.67%) |
| Chilomastix mesnili | 40 (0.41%) |
| Hook worm | 36 (0.36%) |
| Trichuris trichuria | 36 (0.36%) |
| Entamoeba histolytica | 14 (0.14%) |
| Hymenolpis nana | 10 (0.10%) |
| Strongloyides larva | 7 (0.07%) |
| Trichomonas hominis | 6 (0.06%) |
| Schistosoma mansoni | 4 (0.04%) |
| Balantidium coli | 4 (0.04%) |
| Enterobius vermicuolaris | 2 (0.02%) |
| Taenia species | 1 (0.01%) |
The specimens tested for the presence of parasites were 9869 in number while 271 specimens were tested both for parasites and occult blood. On the other hand, 521 specimens were tested only for occult blood. In the specimens tested for parasites, the parasites found were pathogenic and/or non-pathogenic intestinal parasites.
It is worth mentioning that among the specimens tested, 167 samples were loose stools samples. In 45 (27%) of such samples, only blood and mucous were found, otherwise all the samples were devoid of parasites.
Among the specimens tested for occult blood 154 (19.4%) were found to be positive for occult blood, while 44 (5.6%) were slightly positive for occult blood (Table 4).
Table 4.
The results of the occult blood analysis.
| Result | Number |
|---|---|
| Negative for occult blood | 594 (75.00%) |
| Slightly positive for occult blood | 44 (5.56%) |
| Positive for occult blood | 154 (19.44%) |
| Total | 792 (100%) |
As regards the information about the nationality, age and sex of the tested population is concerned, it was known only for 1599, 888 and 10,003, respectively. The frequencies of the available: nationality, age groups and sex of the tested population are shown in (Tables 5–7).
Table 5.
The distribution according to the Nationalities.
| Nationality | Number |
|---|---|
| Saudi | 1203 (75.23%) |
| Non-Saudi | 396 (24.77%) |
| Total | 1599 (100.00%) |
Table 6.
The distribution according to the sex.
| Sex | Number |
|---|---|
| Males | 3692 (36.91%) |
| Females | 6311 (63.09%) |
| Total | 10,003 (100.00%) |
Table 7.
The distribution according to the age range including the mean and standard deviation.
| Age Range in years | Number |
|---|---|
| <10 | 35 (3.94%) |
| 10–<20 | 104 (11.71%) |
| 20–<30 | 151 (17.00%) |
| 30–<40 | 179 (20.16%) |
| 40–<50 | 179 (20.16%) |
| 50–<60 | 112 (12.61%) |
| 60–<70 | 73 (8.22%) |
| 70–<80 | 33 (3.72%) |
| 80–<90 | 18 (2.03%) |
| >90 | 4 (0.45%) |
| Total | 888 (100.00%) |
| Mean and standard deviation | 40.93 ± 19.26 |
4. Discussion
Based on the results obtained during the current study in Riyadh (Saudi Arabia), on the prevalence of intestinal parasitic diseases, a small percent of the samples were found positive for pathogenic and/or non-pathogenic or both type of parasites. The most common infections were due the non-pathogenic organisms namely, E. coli, Iodamoeba buetschilii and Endolimax nana. The percents of the different pathogenic organisms found are shown in (Table 3). Ascaris and G. lamblia being the most predominant 66 (0.67%) each while Taenia infection being the least common 1 (0.01%). If the different percentages are added they will give an overall percentage of 10.6%, however, this will be misleading as it includes the percentage of some parasites counted twice as a single infection and in case of multiple infections.
Our findings are not in full agreements with the earlier reports where overall high parasitic infection rate of 32.2% was reported in Riyadh, depending on sociodemographic and environmental factors (Al-Shammari et al., 2001).
Earlier, in a study on closed children communities: a children’s nursery, a foster house and a rehabilitation centre in Abha (Saudi Arabia), an overall infection rate of 30% was recorded. It was well documented that the children were infected by G. lamblia and/or Entamoeba species. The infection rate was found to be significantly higher in the rehabilitation centre followed by children’s nursery and foster house. However, E. histolytical infection was observed only in the rehabilitation centre with the infection rate of 18.4% (Omar et al., 1991; Al-Eissa et al., 1995). The results of a community based study conducted in Al-Baha region (Saudi Arabia), showed the infection rate of 21.1% in children with 5–9 years of age irrespected of sex differences. The parasites found were: G. lamblia 9%, E. histolytica 5%, Hymenolepis nana 2%, and Enterobius vermicularis 2% (Al-Eissa et al., 1995). On the other side, the data of earlier national survey on the prevalence of pathogenic intestinal parasites in rural Saudi Arabian school children (aged: 6–18 years) showed the following trend: G. lamblia (13.5%), S. mansoni (3.8%), E. histolytica (2.5%), H. nana (2.5%), A. lumbricoides (2.0%) and E. vermicularis (1.0%) (Al-Sekait et al., 1993).
Among the symptomatic patients clinically suspected of intestinal infection lead by E. histolytical, 54% of these patients were found positive in hemagglutination test serologically and microscopic stool analysis. It was interesting to notice that E. histolytical infection was also observed in 0.9% of the subjects in the control group (Hossain et al., 1989).
As regards the parasitic infection rates among expatriate workers in Al-Khobar area (Saudi Arabia) is concerned, the overall infection rate was (31.4%), patients with single infections were (22.3%) and with multiple infections (9.1%). The most dominant parasites found among those workers were: Hookworms, T. trichiura, and A. lumbricoides. The parasitic rate was highest in Indian workers followed by Indonesians, Filipinos and lastly Sri Lankans (Abahussain, 2005).
The low infection prevalences observed in our present study may be due to the fact that all the stool samples were obtained from the hospitalized patients while other studies were community based surveys including high risk groups such as school children and rehabilitation centres. There is an ample possibility that the samples included in our study might have been from the patients already on treatment and in recovery phase, hence low parasite density was observed. The genuine geographical variation and improvement in the public health in general may also play a role in reduction in parasitic infections, however, unnecessary delay in bringing the sample specimens to our laboratory might lead to the death of parasites such as E. trophozoites (WHO, 1991; Panjarathinam, 2007). Furthermore, some of the hospital specimens with high clinical suspicion might have been excluded due to deficient clinical data provided by the hospital staff.
It is worth mentioning that in the current study, among the specimens tested, 167 samples were loose stools samples. In 27% of such samples only blood and mucous were found, otherwise all the samples were devoid of parasites. As regards the prevalence of occult blood is concerned, it was found to be high (25%) as compared to results of earlier studies conducted in different regions of Saudi Arabia including Riyadh region. The higher prevalence of occult blood observed in the present study may be attributed to the factor that the patient tested were not randomly selected rather the requests were based on clinical symptoms indicating the test.
Based on our current findings, it may be concluded that the prevalence of intestinal parasitic disease in Riyadh region is now not as high as reported before. Furthermore, the non-pathogenic organisms were more common as compared to the pathogenic parasites. The differences between the current study results and the data presented in earlier reports might be due to certain reasons such as: improper collection of sample specimens, poor reporting or in some case even no clinical remarks given on the data sheets of the specimens submitted, delay in sample transport, geographical variations, and to the improvement in public health over the years. It is therefore, suggested that a better communication between the clinical staff and laboratory requirements should be promoted, and this goal may be achieved by joint lectures and training programmes.
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