Abstract

Effective control of parasitic infestation of humans involves relatively low-cost interventions. Informed decisions about need of investment in control programmes, however, requires useable estimates of the scale of morbidity. To assess the morbidity in and around Mumbai a total of 1924 stool samples were collected from patients of Sir J. J. Hospital, Mumbai and screened microscopically for the presence of parasitic ova and cysts. 5.97% of the samples screened were positive for different parasitic ova and cysts. Helminthic ova were present in 79.09% and protozoal cysts were present in 14.76%. The common helminthic ova detected were Ascaris lumbricoides 51 (44.34%) followed by Trichuris trichura 20 (17.39%), Ankylostoma duodenale 10 (8.69%), Hymenolepis nana 5 (4.34%), Taenia 4 (3.47%) and Enterobius vermicularis 1 (0.86%). In 7 (6.08%) patients Strongyloides stercoralis larvae were seen. All these were from HIV positive patients. The common protozoal cysts seen were Balantidium coli 7 (6.08%) followed by Giardia lamblia 6 (5.21%) and Entamoeba histolytica 4 (3.47%). No seasonal variations were observed.

Introduction

Parasitic infestations rarely cause mortality hence are often considered relatively unimportant. However, they are a significant cause of nutritional deficiencies in developing countries.1 The incidence of parasitic infestation of intestine is an indicator of the hygiene of the population, awareness of proper sanitary facilities and awareness of safe potable drinking water.

Low-cost interventions can control parasitic infestations or at least decrease the incidence of these infestations. It is thus important to know disease burden of parasitic infestations in the communities. Data regarding the prevalence and incidence of intestinal parasites in humans is meager in this country. Much of it is because of lack of interest on the part of physicians to undertake such work. It is also due to certain intrinsic difficulties involved in carrying out stool surveys.2 The present study is a retrospective study to assess the incidence of parasitic infestations in patients coming to Sir J. J. Hospital with vague abdominal symptoms and or anaemia where the clinicians requested a stool examination to rule out parasites.

Material and Methods

A retrospective analysis of prevalence of various parasites during the 18 months period was done in the department of Microbiology, Grant Medical College and Sir J.J. Group of Hospitals, Mumbai. Total 1924 stool samples were received from outdoor and indoor patients of Sir J.J. Hospital. All the samples were subjected to routine microscopy with normal saline wet mount and Lugol’s iodine mount simultaneously. Harada mori technique was performed to hatch the filariform larvae from eggs of hookworm.3,4 This technique was used to differentiate between the filariform larvae of hookworm and Stronglyloides stercoralis.3

Harada-mori Technique4:- Filter paper strip of 15 cm x 1.5 cm diameter was taken. 500 mg of faeces were smeared on middle one third of a filter paper strip. This strip was then placed in a conical centrifuge tube with sterile water in such a way that the lower unsmeared end dips in water. This preparation was then incubated for 8 days at room temperature after sealing its mouth. After 8 days of incubation, larvae developed on the filter paper strip and fell down in water. First, with the help of magnifying lens all these larvae were examined. This technique enabled us to see the differences between filariform larvae of Ankylostoma duodenale and Stronglyloides stercoralis.

Observations and Results

Parasites were detected from 115 (5.97%) of the stool samples received. Table 1 shows that the 49.37% of the total 1924 stool samples were from males and 50.62% were from females. The proportion of positive samples was similar in males and females but distinctly decreased as age advanced. 86 i.e. 5.30% from 1620 adult were positive for different parasites. 29 i.e. 9.53% from 304 children were positive for different parasites. In this study, children group was more

Table 1 : Shows age and sex-wise distribution of parasites

affected in both the sexes.

Analysis of the positive stools season-wise showed no significant difference in the incidence of parasitic infestation over the year though more were detected in the months of April and May 2002. Helminths formed 85.17% of the total parasitic infestation. Commonest helminth detected were Ascaris lumbricoides 51 (44.34%) and least detected were Enterobius vermicularis 1 (0.86%) as shown in Fig. 1. All 7 (6.08%) Strongyloides stercoralis larvae were from HIV positive patients. Protozoal cysts were seen in 14.76% of the sample received. The commonest protozoal cysts seen were Balantidium coli 7 (6.08%) and least common were Entamoeba histolytica 4 (3.47%) (Fig. 1).

Discussion

A single stool examination on a hospital-based population was used to focus attention on the distribution of pathogenic intestinal parasitic infestation in Mumbai. In the present study a total 1924 stool samples were received from patients of Sir J.J. Hospital, Mumbai with complaints of vague abdominal symptoms and or anaemia. 115 i.e. 5.97% were detected positive for intestinal parasites. Previous reports from India have showed infestation rate ranging from 38% to 75%.5,6 Patel has reported the 75% infestation rate in the year 1986 from Mumbai.6 After 20

Fig. 1 : Parasite prevalence.

years, we have found 5.97% infestation rate. This decrease in the intestinal parasitic infestation may be a reflection of improvement in sanitation or an increased awareness amongst the population.

Helminthic infestations were much commoner than protozoal infestation in our study. 85.17% of the positive samples showed helminthic infestation, however, 14.76% of the positive samples showed protozoal infestation. Vidyarthi reported 22.7% of incidence of helminthic infestation.2 However Prakash and Tandon reported 24.13%, Patel 35.5% and Sharma reported 36.25% incidence for helminthic infestation respectively.5-7 The higher positivity rate for helminthic infestation in our study could be due to the fact that ours was a hospital based study and selection criteria for inclusion was a vague abdominal pain and anaemia and not diarrhoea was included.

Commonest helminth found was Ascaris lumbricoides (44.34%) followed by Trichuris trichura(17.39%). Ankylostoma duodenale (8.69%) and Strongyloides stercoralis (6.08%) respectively. Similar study was conducted by Shrivastava in1953 in Bombay reported 20.2% incidence for A.lumbricoides.8

Number of studies from different parts of India have shown infestation rate varying from 0.6% by Prakash and Tandon, 0.86% by Sharma, 7.19% by Vidyarthi, 16.3% by Gadgil 35.7% and by Patel for A.lumbricoides respectively.5,7,2,9,6

Trichuris trichura were detected from 17.39% of patients in this study, which correlates with other studies.6,8 In the present study A. duodenale were detected from 8.69% of cases, however, other studies have shown a high incidence for A. duodenale.2,6,8 The highest incidence reported was 32.52% by Sharma et al from a high altitude area of New Kangra District in Himachal Pradesh.7 Such a high percentage rate highlights the poor sanitary status of the community in that area. A Steady decrease in incidence of an A. duodenale in recent years is encouraging and may reflect an increased awareness and increased use of footwear. In the present study Strongyloides stercoralis larvae incidence is high i.e. 6.08%. This is an opportunistic infection associated with HIV infection and is a reflection of the number of HIV positive patients in Mumbai. This parasitic larva causes chronic diarrhoea as well as acute dysentery. An earlier report from Mumbai found 5.3% incidence of this larva from diarrhoeal cases of AIDS patients in year 2002.10

Incidence for protozoa in our study was 14.76%, which was similar to Sharma et al (14.96%).7 In the other studies infestation rate for protozoa was 6.85%, 39.4% and 75.86% respectively.2,6,5 Commonest protozoa detected was Balantidium coli (6.08%), followed by Giardia lamblia (5.21%) and Entamoeba histolytica (3.47%) respectively. Vidyarthi reported much lower (1.04%) incidence for B. coli from Lucknow in 1969.2 The second most common protozoa detected in our study was G. lamblia with an infestation rate of 5.21% however, other studies showed high incidence for this parasite ranging from 10.50% to 10.1% and 21.5%.7,5,8 Similarly the incidence of E.histolytica was 3.47% in our study, however, other studies showed a high incidence varying from 4.46%, 14.9%, 18.4%, 35.6% and 39.7% for this parasite.7,10,5,8,6 In 1945 from Mumbai Patel reported a very high incidence i.e. 43.3% for E. histolytica.11

The decrease in incidence for protozoa in our study is because protozoa may reflect better water quality in and around Mumbai in present days. However, the increase incidence of B. coli in our study is interesting, could be a relative increase reflecting the decrease in patients of amoebiasis due to better drugs and prompt treatment.

Conclusion

To conclude, the present study shows a decrease in the incidence of parasitic infestations in Mumbai over the last 50 years. Thus, the currently ‘in place’ interventions are definitely having effect on. However, it also highlights the fact that inspite of the easy availability of antihelminthics and antiprotozoal drugs, these conditions are not yet eradicated. And there is need to upscale the interventions currently in place would go a long way in decreasing the malnutrition deficiencies and loss of man hours caused by these infestations.

Regular surveys regarding the prevalence of intestinal parasites in the hospitals and communities serve a very useful purpose and should be an ongoing process.

References

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*Lecturer, **Professor, ***Professor and Head, Department of Microbiology, Grant Medical College and Sir J. J. Group of Hospitals, Mumbai – 400008.