Page 202 - Textbook of Pathology, 6th Edition

186 CLINICAL FEATURES. The disease has the usual flu-like LYMPHOGRANULOMA VENEREUM
clinical features, but additionally one-third of cases have been Lymphogranuloma venereum (LGV) is a sexually-
found to have diarrhoea and vomiting. transmitted disease caused by Chlamydia trachomatis and is
Since human beings do not have immune protection by
antibody response against H1N1 influenza type A and the characterised by mucocutaneous lesions and regional
lymphadenopathy. Though described here under viral
usual seasonal flu vaccine does not provide protection against infections, chlamydia are no more considered as filterable
H1N1, personal hygiene and prophylaxis remain the mainstay viruses as was previously thought but are instead
of further spread of disease.
intracellular gram-negative bacteria. LGV is worldwide in
distribution but its prevalence rate is high in tropics and
SECTION I
VARICELLA ZOSTER VIRUS INFECTION subtropics in Africa, South-East Asia and India.
The condition begins as a painless, herpes-like lesion on
Varicella zoster virus is a member of herpes virus family and the cervix, vagina, or penis. The organisms are carried via
causes chickenpox (varicella) in non-immune individuals and lymphatics to regional lymph nodes. The involved lymph
herpes zoster (shingles) in those who had chickenpox in the nodes are tender, fluctuant and may ulcerate and drain pus.
past.
Microscopically, the lymph nodes have characteristic
Varicella or chickenpox is an acute vesicular exanthem stellate-shaped abscesses surrounded by a zone of
occurring in non-immune persons, especially children. The epithelioid cells (granuloma). Healing stage of the acute
condition begins as an infection of the nasopharynx. On lesion takes place by fibrosis and permanent destruction
entering the blood stream, viraemia is accompanied by onset of lymphoid structure.
of fever, malaise and anorexia. Maculopapular skin rash,
usually on the upper trunk and face, develops in a day or CAT-SCRATCH DISEASE
two. This is followed by formation of vesicles which rupture Another condition related to LGV, cat-scratch disease, is
and heal with formation of scabs. A few cases may develop caused by Bartonella henselae, an organism linked to rickettsiae
complications which include pneumonia, hepatitis, but unlike rickettsiae this organism can be grown in culture.
encephalitis, carditis, orchitis, arthritis, and haemorrhages. The condition occurs more commonly in children (under 18
Herpes zoster or shingles is a recurrent, painful, vesicular years of age). There is regional nodal enlargement which
eruption caused by reactivation of dormant varicella zoster appears about 2 weeks after cat-scratch, and sometimes after
virus in an individual who had chickenpox in the earlier thorn injury. The lymphadenopathy is self-limited and
years. The condition is infectious and spreads to children. regresses in 2-4 months.
General Pathology and Basic Techniques
The virus during the latent period resides in the dorsal root Microscopically the changes in lymph node are
spinal ganglia or in the cranial nerve ganglia. On reactivation, characteristics:
the virus spreads from the ganglia to the sensory nerves and i) Initially, there is formation of non-caseating sarcoid-
to peripheral nerves. Unlike chickenpox, the vesicles in like granulomas.
shingles are seen in one or more of the sensory dermatomes ii) Subsequently, there are neutrophilic abscesses
and along the peripheral nerves. The lesions are particularly surrounded by pallisaded histiocytes and fibroblasts, an
painful as compared with painless eruptions in chickenpox. appearance simulating LGV discussed above.
iii) The organism is extracellular and can be identified by
HERPES SIMPLEX VIRUS INFECTION silver stains.

Two of the herpes simplex viruses (HSV)—type 1 and 2, RABIES
cause ‘fever blisters’ and herpes genitalis respectively. Rabies is a fatal form of encephalitis in humans caused by
HSV-1 causes vesicular lesions on the skin, lips and
mucous membranes. The infection spreads by close contact. rabies virus. The virus is transmitted into the human body
by a bite by infected carnivores e.g. dog, wolf, fox and bats.
The condition is particularly severe in immunodeficient The virus spreads from the contaminated saliva of these
patients and neonates while milder attacks of infection cause animals. The organism enters a peripheral nerve and then
fever-blisters on lips, oral mucosa and skin. Severe cases may travels to the spinal cord and brain. A latent period of 10
develop complications such as meningoencephalitis and days to 3 months may elapse between the bite and onset of
keratoconjunctivitis. Various stimuli such as fever, stress and symptoms. Since the virus localises at the brainstem, it
respiratory infection reactivate latent virus lying in the produces classical symptoms of difficulty in swallowing and
ganglia and result in recurrent attacks of blisters. painful spasm of the throat termed hydrophobia. Other
HSV-2 causes herpes genitalis characterised by vesicular clinical features such as irritability, seizure and delirium point
and necrotising lesions on the cervix, vagina and vulva. Like towards viral encephalopathy. Death occurs within a period
HSV-1 infection, lesions caused by HSV-2 are also recurrent of a few weeks.
and develop in non-immune individuals. Latency of HSV-2 Microscopically, neurons of the brainstem show
infection is similar to HSV-1 and the organisms are characteristic Negri bodies which are intracytoplasmic,
reactivated by stimuli such as menstruation and sexual deeply eosinophilic inclusions.
intercourse.