Report

Human cowpox infection in Sharkia Governorate, Egypt

Mohamed Amer, MD, I. El-Gharib, MD, A. Rashed, MD, F. Farag, MD, and M. Emara, MD

Abstract

Background and objective In the last few years, outbreaks of an apparently speci®c

dermatosis occurred during the months of late summer and early autumn in our locality. Our

aim in this study was to reveal the underlying etiology of this dermatosis.

Subjects and methods Sixty patients with the disease were studied clinically, epidemio-

logically, histopathologically, and ultrastructurally.

Results The results of all methods suggest that the dermatosis is most probably a human

cowpox infection. Electron microscopy showed unenveloped cowpox virons.

Conclusions This apparently speci®c dermatosis is due to human cowpox infection. Future

investigations will be needed to better de®ne this important zoonosis frequently passed by

cats to humans and carried by rodents.

In the last few years, outbreaks of an apparently speci®c

dermatosis occured during the months of late summer and

early autumn.

Clinically, patients with this dermatosis presented with

brownish burning erythema which may or may not blister.

These lesions usually affected the exposed parts. If the

lesion occurred near the eyes conjunctivitis sometimes

occurred. Healing usually occurred after two weeks but the

course of the disease is recurrent in some cases1 during

these months.

In 1994, Baxby et al. reviewed 54 cases of human

cowpox which were reported from all over Europe during

the previous 15 years. These cases showed great similarity

to and the same seasonal variations as our dermatosis.

Their results stimulated us to investigate our cases to prove

or disprove that this dermatosis is a human cowpox

infection.

Cowpox virus is an orthopoxvirus endemic in Europe

and some western states of the former USSR,2 and is a mild

eruptive disease of the teats and udders of cattle.3 Human

cowpox is a zoonosis, but despite its name, cows are

involved only rarely. The most commonly detected source

of human infection is the domestic cat and the virus is

probably maintained in wild rodent populations.2 Cowpox

is acquired by implantation of the virus into broken skin.1

Patients and methods

Sixty patient attending the Outpatients Clinic of the Department of

Dermatology at Zagazig Medical Center, Egypt, during the

months of summer and autumn of 1996, 1997 and 1998 and

complaining of manifestations of summer autumn dermatosis

were collected randomly and subjected to thorough clinical

epidemiologic evaluation and histopathologic examinations of

skin biopsy specimens. Vesicle ¯uid or scab extracts from ®ve

patients were evaluated by electron microscopy, the most

de®nitive method for viral skin infections.3

Results

Clinical and epidemiological results

Typically, the lesion of this summer autumn dermatosis

starts suddenly as a brownish, burning erythematous

macule and, over a period of about one week, passes

through papular and vesicular stages. Vesicles usually

appeared in the center of the patch (Fig. 1). The vesicle

became pale blue±purple and increasingly hemorrhagic

(Fig. 2). It evolved via a pustule which began to ulcerate

and crusted over by the end of the second week. Recovery

occured by postin¯ammatory hyperpigmented brownish

macule, but without scaring, in 3±4 weeks, but in some

cases it persisted for 6±8 weeks.

Fifty of 60 cases studied (83%) had only one lesion in the

exposed parts (face, neck, and hand). In the remaining 10

cases (17%), the eruption is generalized (Fig. 3).

Generalization of the lesion may be due to accidental

transfer from a developing primary lesion in the hand.1

The lesion is invariably painful, sometimes extremely so,

and local lymphadenopathy was recorded in only one case.

There was usually edema (Figs 1 and 2), which was not

indurated or woody.

From the Departments of

Dermatology and Pathology Zagazig

University, Zagazig, Sharkia

Governorate, Egypt

Correspondence

Mohamed Amer, MD

Department of Dermatology

Zagazig University

Zagazig

Sharkia Governorate

Egypt

International Journal of Dermatology 2001, 40, 14±17 ã 2001 Blackwell Science Ltd

14

In¯uenza-like illness in the form of pyrexia, malaise, and

lethargy was recorded in only 3 cases (5%).

Table 1 summarizes the location of lesions of human

cowpox infection in relation to age of patients and Table 2

summarizes the relation between living areas (rural or

urban) of the patients and their age.

Histopathologic results

The specimens studied showed that there was massive

intercellular and intracellular edema in the epidermis with

dense dermal polymorphnuclear leucocytic in®ltration

encroaching, on the epithelium (Fig. 4).

Electron microscopy results

Electron microscopic examination of vesicle ¯uid or scab

extract from only ®ve patients showed unenveloped cow-

pox virons which are either brick-shaped with rounded

corners or of beaded appearance. The characteristic

structure of the outer membrane or surface of randomly

arranged short rodlets or tubules was evident (Fig. 5).

Discussion

The nature of the lesions, the limited course of the disease,

its seasonal variations, occurence in rural more than urban

individuals, and in men (more contact with wildlife) more

than in women, its association with exposed parts more

than hidden parts, and the histopathologic ®ndings of our

summer autumn dermatosis, are all consistent with cases of

Figure 1 Human cowpox infection, brownish erythematous

macule with central vesicleFigure 2 Erythema with hemorrhogic blister and periorbital

edema

Figure 3 Generalized eruption

Amer et al. Cowpox in Egypt Report

ã 2001 Blackwell Science Ltd International Journal of Dermatology 2001, 40, 14±17

15

human of cowpox reported in Europe, which is the

endemic continent of this of this disease.1,3,4

Minimal clinical variations were present between our

patients and the European cases of human cowpox. The

edema presenting in our cases is not woody or indurated,

and not prolonged. Local lymphadenopathy occured rarely

(1 out of 60) in our patients, similarly the ¯u-like illness (3

out of 60). Lastly, healing in our patients occurred by

postin¯ammatory hyperpigmentation but without the

scarring that may occur in some European cases.1

An additional support that these patients are cases of

human cowpox is the presence of the characteristic brick-

shaped form of cowpox virus as intercytoplasmic inclu-

sions, shown by electron microscopy study of their scab

extract.

From all of the above we can conclude that these

outbreaks of summer±autumn dermatosis in Egypt are

most probably cases of human cowpox, but before a ®nal

decision the following investigations must be performed:

1 electron microscopy study of vesicle ¯uid of a larger

sample of patients;

2 con®rmation of diagnosis by inoculation into cultured

cells (Vero) and the chorioallantoic membrane of fertile

hens eggs and demonstration of typical cytopathic effect;5

3 serodiagnosis: a titer by virus neutralization 1:400 and

hemagglutination inhibition 1:64 in a convalescent serum

to con®rm infection by cowpox;

4 serological survey of our region's rodents and domestic

cats to detect their infection with cowpox virus.

Table 1 Human Cowpox: location of lesions in relation to age and

sex patients

Age (years)

Location of lesion Total <12 12±18 >18

Exposed parts (hand, face & neck) 50 12 10 28

Generalized (Exposed and hidden) 10 3 2 5

Total 60 15 12 33

Table 2 Living areas (rural or urban) of patients in relationto their age

Age (years)

Living area Total <12 12±18 >18

Rural 47 11 9 27

Urban 13 4 3 6

Total 60 15 12 33

Figure 4 Massive intercellular and intracellular edema in the

epidermis with dense dermal polymorphnuclear leucocytic

in®ltration encroaching on the epithelium

Figure 5 Electron microscopy (3 200 000) showed negatively

stained preparations of cowpox virus showing unenveloped

virons which are either brick-shaped with rounded corners

or of beaded appearance. The characteristic structure of the

outer membrane or surface of randomly arranged short

rodlets or tubules is visible (bar, 100 nm)

Report Cowpox in Egypt Amer et al.

International Journal of Dermatology 2001, 40, 14±17 ã 2001 Blackwell Science Ltd

16

The occurrence of these outbreaks during the late

summer and autumn is explained by the fact that this is

the period where the number and activity of wild rodents

are maximal.

The discontinuation of routine smallpox vaccination

since early 1970 (which is derived from cowpox) and an

increase in the number of immunosuppressed patients

because of increased usage of immunosuppressive drugs

and to lesser extent because of HIV infection, may be the

cause of increased number of cases of human cowpox.6

Since human cowpox infection may present by severe

Kaposi varicelliform eruption in patients with atopic

dermatitis we should warn patients with atopic dermatitis

and immunosuppressed patients to be cautious about

handling cats, especially if the animals are active hunters

or have any skin lesions.6

Acknowledgments

Dr Ali A. A. Lecturer of Virology, Faculty of Veterinary

Medicine, Zagazig University provided valuable comments

on the EM images.

References

1 Baxby D, Bennett M, Getty B. Human cowpox 1969±93. A

review based on 54 cases. Br J Dermatol 1994; 131:

598±607.

2 Crouch AC, Baxby D, McCracken CM, et al. Serological

evidence for the reservoir hosts of cowpox virus in British

wildlife. Epidem Infect 1995; 115: 185±191.

3 Burton JL. Of mice and milkmaids, cats and cowpox.

Lancet 1994; 343: 343±367.

4 Lewis-Jones MS, Baxby D, Cefal C, et al. Cowpox can

mimic anthrax. Br J Dermatol 1993; 129: 625±627.

5 Naidoo J, Baxby D, Bennett M, et al. Characterization of

orthopox virus isolated from feline in Britain. Arch Virol

1992; 125: 261±272.

6 Blackford S, Roberts DL, Thomas PD. Cowpox infection

causing a generalized eruption in a patient with atopic

dermatitis Br. J Dermatol 1993; 124: 628±629.

Amer et al. Cowpox in Egypt Report

ã 2001 Blackwell Science Ltd International Journal of Dermatology 2001, 40, 14±17

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