Diagnosing AIDS and Emerging Infections in Resource-Limited Settings:
The Role of the Pathologist in Patient Care and Disease Surveillance
Section 2 -
Patrick Adegboyega and Martin Hale
The practice of histopathology is largely unchanged since the time of Virchow when he established it
the 1850's. Although the principles of the technology are old, there are a number of advantages to
this. Firstly, the equipment required is minimal and is relatively cheap to purchase at entry level,
comprising, rotary processors and microtomes. In addition, the equipment can be expected to have a long
service life if properly serviced and maintained.
Tissue blocks embedded in wax are easy to prepare and store indefinitely and there are no specific
environmental requirements other than good light to cut the H&E sections. Processing reagents are
generally easily and readily available and there are no strict storage or transport requirements other
than protection from fire. These advantages need to be compared with the requirements for the practice
of Clinical Pathology.
The analysers used in Clinical Pathology are complex instruments and have a high level of technology
including the use of sophisticated computer interfaces. The equipment also has high maintenance
requirements sourced from within the laboratory and from equipment suppliers. The reagents that are
utilized are usually in the form of kits and have demanding storage requirements, often including the
integrity of cold chains.
Returning to histology, the processing of tissue is relatively straightforward provided that
recognised standards and protocols are adhered to, such as, the number of baths, the frequency of
solution changes and temperature ranges. It is important that histology laboratories do not look to
achieve false economies or short cuts in any of these activities. Histopathology practice is founded on
adequate tissue fixation and processing and any defects in fixation, dehydration, clearing and waxing
impregnation may cause irretrievable loss, leading to sub-optimal diagnosis. In addition to the H&E
stain there are a number of straightforward special stains that may be employed in the diagnosis of
specific entities and infections, without resorting to complex immunohistochemistry and molecular
The ever-increasing global onslaught of HIV infection and associated immunosuppression in affected
patients highlights the need for timely diagnosis and optimal treatment as a basis for good disease
surveillance and interventional strategies. Unfortunately, many of the regions most affected by this
burden are in underdeveloped countries and so often lack the resources for the timely diagnosis and
management of these disease conditions.
Using an illustrative case presentation approach, the use of basic, reliable, readily available and
cost-effective histochemical stains and techniques for the tissue diagnosis of infectious diseases in
resources-limited settings will be discussed. This will include ways in which the histopathologist can
be actively involved in the diagnosis and surveillance of emerging/re-emerging infectious diseases.