Comparism of various staining techniques in the diagnosis of coccidian parasitosis in HIV infection

Abstract

Background: Diarrhoea due to opportunistic coccidian parasites is a common clinical presentation in HIV infection. Its management differs from that of diarrhoea due to other protozoa, improvement of immune status being the mainstay while specific drug treatment is available for other aetiologies, hence, the need for its accurate identification when present. This can be achieved via various diagnostic techniques, commonly microscopy in this environment, hence the need to compare the efficacy of the commonly used stains in our locality.

Objective: To identify the most effective of the commonly used stains in identifying these parasites.

Methods: Diarrhoea stool samples from 250 adult HIV positives and an equal number of age and sex matched HIV negative controls were screened, staining with trichrome, auramine and modified Ziehl–Neelsen stain.

Results: A positivity rate of 55% was reported. modified Ziehl–Neelsen , when compared with trichrome staining had 81% sensitivity, 77.3% specificity, positive predictive value of 70.4%, negative predictive value of 85.9% and when compared to auramine staining, had 80% sensitivity, 76.7% specificity, positive predictive value of 69.9%, negative predictive value of 85.2% in test subjects. There was a significant moderate level of agreement between the staining methods though Trichrome showed a stronger agreement than Auramine when compared with Modified ZN in test (ê value 0.569 and 0.553 respectively), and a significant, fair level of agreement between the methods with Auramine showing a stronger agreement than Trichrome when both were compared with Modified ZN (ê value 0.399 and 0.332 respectively) in controls.

Conclusion: Auramine and trichrome techniques are preferred for screening and diagnosis based on findings. Of these two techniques, auramine is preferred.