ABSTRACT

Objective

Parasite are living organisms which survive on another living being for their nourishment and survival. When these parasites resides on human body, they bring about inflammatory response. This inflammatory response leads to tissue reaction. Tissue response on microscopy appear as an eosinophilia, abscess and granulomas. This study was planned with the objective to know the frequency of parasite infection, tissue response in parasite infection and its comparison in terms of variables like age, sex and the type of parasite.

Methods

This is a retrospective study, conducted in the department of pathology. A total of 26 cases of parasitic infections in human specimens reported in our department from January 2008 to December 2019 were included in this study. On all archived cases hematoxylin and eosin and where ever required periodic acid schiff was applied. These slides were thoroughly examined and clinicopathological correlation was studied.

Results

Age range of patients was 5 years to 70 years. Maximum number of patients were belonging to 11-20 year age group. Male to female ratio was 1:2. Among the 26 cases, there were 9 cases (34.62%) of hydatid cyst, six cases of Entamoeba histolytica (23.07%), four cases of Enterobious vermicularis (15.38%), and two cases (7.69%) each of Ascaris lumbricoides, filaria and cysticercosis respectively. A specific tissue response seen in cysticercosis having chronic inflammatory cells, palisaded epithelioid cells granuloma and giant cell reaction while other showed inflammatory cells infiltration.

Conclusion

Clinically diagnosis of parasitic infection in each and every case is not possible, similarly radiological investigation is also suggestive only. Histopathology examination is the benchmark investigation to diagnose parasite infection and tissue reaction to the host. Histopathology examination must be implicated in every case to identify parasite and tissue reaction so that the patients can be managed accordingly before the complications rises.

INTRODUCTION

The parasite is a living organism that lives in or on another living organism which is known as host. Parasite obtains nourishment and protection from host and consequently causes infections leading to tissue reaction. Tissue reaction causes inflammatory reaction which occurred due to human parasites. Human parasites were classified in few major divisions, including Protozoa, Fungi, Platyhelminthes (cestodes, trematodes), Nematode and Arthropod (insects, spiders, mites, tick, etc.). The common parasitic infection are like amoeba in the intestine causing amoebic colitis (1), filariasis in scrotum (2), Echinococcus causing hydatid cyst in liver (3) and Cysticercosis caused by larval cysts of the tapeworm Taenia solium (4).

Histomorphological features are helpful in the diagnosis of human and animal diseases of different etiologies. In many cases, parasitic diseases are not properly recognized on routine laboratory investigations. An insufficient diagnosis often leads to wrong or ineffective treatment. On histopathology, these parasites produce tissue responses which provides clue in the identification of parasites and finally reaching at the correct diagnosis, thus histopathological examination of affected organs or tissues facilitates a concise and accurate diagnosis which is helping in planning the precise and correct treatment (1, 5).

Histopathology stains like haematoxylin and eosin and periodic acid schiff are not only fruitful in the identification of the parasite but also in the predicting host tissue response (2, 6). As per authors knowledge no such study is performed till date so, this study was planned with the objective to know the tissue response against the parasite infection and its comparison in terms of variables like age, sex, type of parasite.

METHODS

This was a retrospective study, conducted in the department of pathology. All the 26 cases of parasitic infections in human specimens reported in our department from January 2008 to December 2019 were included in this study. All the clinical details like age and sex of patients, and site of lesion along with radiological findings where ever available were noted from the histopathology record register.

All archived H and E stained slides of each case were thoroughly examined for histological identification of the parasite and the various tissue reactions elicited against each parasitic infection. Special stains such as PAS were also performed where ever required to confirm diagnosis, such as in cases of amoebic colitis.

Statistical Analysis

Statistical analysis was done by percentage.

Ethical clearance was taken from Institutional Ethical Committee of Uttar Pradesh University with ethical clearance no: 228/2018.

Consent of patients were not taken, as we had received tissue for histopathology examination and details were obtained from the patients records.

RESULTS

In the present study over a period of 12 years there were 26 cases of parasitic lesions identified on histopathological examination.

Age range of patients was 5 years to 70 years. Nine patients were male while 17 were females with M:F ratio of about 1:2. Females were more infected by parasites.

Maximum number of patients were belonging to 11-20 year age group while minimum cases were belonging to 21-30 year age group (Table 1).

Frequency of various parasitic infections is summarised in
(Table 2). Among the 26 cases, maximum cases were of hydatid cyst comprising of 9 cases (34.62%) followed by
Entamoeba histolytica (23.07%) (Figure 1), Enterobious vermicularis (15.38%) (Figures 2, 3), and (7.69%) Ascaris lubricoides, (7.69%), filaria (Figures 4, 5) and cysticercosis (Figure 6) respectively.

There was one case (3.85%) in which no fragment of parasite was seen, but tissue reactions strongly raised the suspicion of parasitic infection. In the same case microfilaria was reported on FNA, but it could not appreciated on histopathology because of resolving parasitic infection (Table 2).

Hydatid cyst was most common parasite reported in this study (34.62%). The peak age for the incidence was 11-56 years followed by others.

DISCUSSION

Parasites may infests humans and cause parasitic diseases. In India, Charak Samhita and Sushutra Samhita documented malaria. The Bhrigu Samhita from 1000 BCE had made earliest documentation of amebiasis. The diagnosis of parasitic infection is mandatory to diagnose the disease. The different diagnostic tests includes stool examination, endoscopy, blood tests including blood film smearing and serology, radiology investigations and histopathology (7, 8). Now a days, PCR is also used for the confirmative diagnosis of parasite and is seen only in higher centres only because it is expensive and requires experience person to manage. Tissue staining with hematoxylin and eosin (H&E) and PAS not only identify parasite but also visualize host tissue reaction (9). So, histopathological examination is the bench mark diagnostic test for identification of various parasitic agents and tissue response.

The government also conducts various policies for the elimination of parasites like filariasis as it causes an important health problem in India (10).

In the present study over a period of 12 years there were 26 cases of parasitic lesions identified on histopathological examination in which parasite was identified in 25 cases and one case there was tissue reactions which strongly raised the suspicion of parasitic infection, as the microfilaria was reported on FNAC in the same patient. Parasite could not visualized on histopathology because of resolving parasitic infection.

Age range of patients was 5 year to 70 year (Table 1) which was comparable with other researchers (9). Most common parasitic infection in our study was hydatid cyst, out of which maximum were located in liver (Table 2). This finding was in concordance with the study done by Rao et al. (11), who reported 72% cases of hydatid cyst in liver.

The difference in incidences of parasitic infection may be because of difference in geographical distribution of various parasitic species.

The peak age range also provide the clue for variant of parasite infection. The youngest patient was seen in peak range of 5-35 years which was reported in ascaris simultaneously the oldest was noted in peak range of 45-70 which was for filaria (Table 3). Age range of the patients diagnosed with hydatid cyst, Entamoeba histolytica, and Filaria was in concordant with study done by Manoharan and Sowmya (9), Sabesan et al. (10)and Rayan et al. (12).

As far as the age distribution for Ascaris lubricoides and Cysticercosis was reported, it was found lower in comparison to these researchers. This difference could be because of scanty number of parasites cases in their studies.

The parasite commonly encounter in humans are filariasis, ascaris, cysticercosis, amoeba, hydatid cyst and entrobious vermicularis (13-15). The most common location of parasite infection was liver in current study. The site/location of parasitic infection was comparable with other researchers (Table 4). The other researchers reported different sites other than liver this discordance may be due to geographical distribution and due to different parasites harboring at different places.

Tissue response in our study was concordant with the study done by Manoharan and Sowmya (9)(Table 5). In other studies eosinophilia was the most presenting finding for parasite infection but in current study eosinophils were rarely recognized ie, 3 cases out of 26 cases have eosinophil cell in tissue reaction.

In contrast to that here, there was predominance of chronic inflammatory cells infiltration. The reason for the presence of chronic inflammatory cells accumulation might be the presence of persistent parasite leading to chronic immune response
(Table 6).

In most cases of hydatid cyst we received only cyst so comment on tissue reaction was not possible. There was only two case of infected hydatid cyst which were found infiltrated by chronic inflammatory cells.

In a case of amoebic colitis initially any amoebic cyst or trophozoite was not appreciated but the mononuclear cell along with eosinophil cells infiltration was so intense which raised suspicion for the parasitic infection. On PAS stain the trophozoites and cyst was well recognized. Similarly Liu et al. (15) applied PAS for the identification of amoebic trophozoite in their study.

PAS staining also enhances the diagnostic efficiency for the identification of parasites. The PAS is a cheaper reagent and the method of PAS staining is equally simple as H&E staining and easily manageable in laboratory. So, it should be applied in histopathology section in daily routine staining to confirm the parasitic infection.

CONCLUSION

We emphasizes on the application of histopathology along with PAS staining for the diagnosis of parasitic infection which not only reduce the morbidity and mortality but also provide correct way for the management to the infected patients. Among tissue response chronic inflammatory cells infiltration was found more frequent and significant. More studies should be carried out with the same aim and including a more numbers of parasitic infected patients.

*Ethics

Ethics Committee Approval: Ethical clearance was taken from Institutional Ethical Committee of Uttar Pradesh University with ethical clearance no: 228/2018.

Informed Consent: Consent of patients were not taken, as we had received tissue for histopathology examination and details were obtained from the patients records.

*Authorship Contributions

Surgical and Medical Practices: M.K., S.D., Concept: M.K., S.D., Design: M.K., S.D., Data Collection or Processing: M.K., Analysis or Interpretation: M.K., S.D., Literature Search: M.K., S.D., Writing: M.K., S.D.

Conflict of Interest: No conflict of interest was declared by the authors.

Financial Disclosure: The authors declared that this study received no financial support.

References

Papparella S. Histology in diagnosis of parasitic diseases. Parasitologia. 2004; 46: 157-8.

Surhonne AP, Surhonne SP. An adult filarial worm in the testicular tissue A case report. Int J Med Sci. 2018; 4: 83-4.

Mohammed AA, Arif SH. Surgical excision of a giant pedunculated hydatid cyst of the liver. J Surg Case Rep. 2019; 7: 1-4.

Del Brutto OH. Neurocysticercosis. Neurohospitalist. 2014; 4: 205-12.

Mahalingashetti PB, Subramanian RA, Jayker SS, Vijay A. Lymphatic filariasis. A view at pathological diversity. Trop Parasitol. 2014; 4: 128-32.

Rivari F, Pampriglione S, Boldorini R, Cardinale L. Histopathology of gastric and duodenal strongyloides stercoralis location in fifteen immunocompromised subject. Arch Path Lab Med. 2006; 130: 1792-8.

Ndao M. Diagnosis of parasitic disease: old and new approaches. Interdiscip Perspect Infect Dis. 2009; 278246.

Hartmeyer GN, Hoegh SV, Skov MN, Dessau RB, Kemp M. Selecting PCR for the Diagnosis of Intestinal Parasitosis: Choice of Targets, Evaluation of In-House Assays, and Comparison with Commercial Kits. J Parasitol Res. 2017; 2017: 6205257.

Manoharan A, Sowmya S. Parasitic infections and their tissue response: a histopathological study. Int J Res Med Sci. 2016; 4: 1938-42.

Sabesan S, Vanamail P, Raju K, Jambulingam P. Lymphatic filariasis in India: Epidemiology and control measures. J Postgrad Med. 2014; 232-8.

Rao SS, Mehra B, Narang R. The spectrum of hydatid disease in rural central India: An 11-year experience. Ann Trop Med Public Health. 2012; 5: 225-30.

Rayan P, Verghese S, McDonnell PA. Geographical location and age affects the incidence of parasitic infestations in school children. Indian J Pathol Microbiol. 2010; 53: 498-502.

Vora SH, Motghare DD, Ferreira AM, Kulkarni MS, Vaz FS. Prevalence of human cysticercosis and taeniasis in rural Goa, India. J Commun Dis. 2008; 40: 147-50.

Dhanabal J, Selvadoss PP, Muthuswamy K. Comparative study of the prevalence of intestinal parasites in low socioeconomic areas from South chennai, India. J Parasitol Res. 2014; 2014: 630968.

Liu YY, Ying Y, Chen C, Hu YK, Yang FF, Shao LY, et al. Primary pulmonary amebic abscess in a patient with pulmonary adenocarcinoma: a case report. Infect Dis Poverty. 2018; 7: 34.

Parasitic Infections and Host Tissue Response in Histopathology: A Rare Retrospective Research Study from Rural India