SMALLPOX (Variola)

Two distinct varieties of smallpox are recognized—variola major and variola minor. The latter was at one time endemic in certain parts of the country; the former is always imported from abroad. Clinically the two types can be similar, but whereas the death rate of major smallpox is around 15 per cent., that of minor smallpox rarely exceeds 0-2 per cent. The minor form is due to a smallpox virus of low virulence and the disease breeds true. Vaccination is equally protective against both forms of the disease.
The virus of smallpox almost certainly enters the body via the respiratory tract. During the course of the infection, virus is discharged in the secretions of the mouth and nose and from the skin lesions. Bed linen is thus heavily infected and the air of the room becomes charged with the virus. Although infection is most often from case to case, papers, clothing, etc., may all act as vehicles, for the virus appears capable of survival for long periods in the dry state. As a result, not only must the isolation of the case be complete but there must be the most stringent disinfection of all clothing and other articles in the sickroom.
Smallpox is a notifiable disease. The incubation period is usually 12 days, but may vary between 10 and 14 days.
Prevention.—The control of smallpox is essentially a public health problem. The accurate diagnosis of the initial case or cases rests, however, with the practitioner, and herein lies a grave responsibility. Early diagnosis, followed by prompt isolation of the primary case, the immediate vaccination and con­tinued supervision of all contacts, and thorough disinfection of the patient's house and its contents are the essentials of successful smallpox control. The practitioner should not hesitate, therefore, to confer with an experienced, consultant regarding any patient who in his opinion might possibly be suffering from smallpox. The misdiagnosis of the initial case or cases as chickenpox has been the starting-point of almost every recent smallpox epidemic in Great Britain.
There can be no doubt as to the wisdom of promptly removing every case of variola major to hospital. During an epidemic of variola minor hospital isolation is desirable so long as accommodation is available. In the event of continued spread of the minor form, circumstances may justify or necessitate home treat­ment. These matters of policy are for the local Medical Officer of Health to decide, but when a case of variola minor is treated at home, isolation of the patient should be strictly enforced and every member of the household vacci­nated.
After the removal of the patient to hospital every known contact should be traced as quickly as possible and subjected to vaccination or revaccination. When possible close contacts such as members of the same household should be isolated either in their own home or in suitable isolation units so that they may be more closely observed. Adult contacts, once they have been vaccinated, may continue their occupations but should be kept under daily surveillance. Intimate contacts who have never been vaccinated are especially at risk. Such persons will, of course, be vaccinated at once but should, in addition, be given a subcutaneous injection of 1-5 to 2-0 g. of hyperimmunegammaglobulm (prepared from persons recently vaccinated against smallpox).
Chemoprophylaxis.—The most significant contribution to the control of smallpox epidemics would be the discovery of a chemical which prevented multiplication of the virus in the cell, for the time of contact is usually known and the incubation period is relatively long. For this reason, therefore, much attention was directed to the use of N-methylisatin /5-thiosemicarbazone (Mar-boran) on a very large scale in India with this prophylactic intention. The results were favourable but so far only a single report of its application is avail­able. Unfortunately the drug proved very toxic in some British trials and further work is, therefore, required before it can be recommended for general use.
Vaccination.—In this highly effective method of prophylaxis against small­pox, introduced by Jenner in 1798, vaccinia, or cowpox, is inoculated into the human subject. Vaccinia is now regarded as a disease attributable to variola virus modified as a result of its passage through animals.
The National Health Service Acts in Great Britain have abolished compulsory vaccination in infancy. It is, however, recommended that vaccination should be part of the programme for child immunization and carried out after the age of one year. Contraindications to this general recommendation are : failure to thrive, the presence of septic skin conditions, chronic eczematous or other manifestations of an allergic nature, the suspicion of hypogammaglobulinaemia or the fact that the individual is receiving corticosteroid preparations.
Fresh glycerinated lymph, which is issued in sealed capillary tubes, should be employed. The lymph should be stored in a refrigerator. The contents of a tube, once unsealed, must not be kept for use on a future occasion. The lymph must be expelled from the tube by a rubber teat—such as that used on an infant's feeding-bottle ; the mouth must not be applied directly to the tube.
The usual site for vaccination is over the insertion of the left deltoid muscle, but for assthetic and other reasons the inner and posterior aspect of the arm or the outer aspect of the thigh or leg may be chosen. The skin should be cleansed with soap and warm water, wiped with ether and dried carefully. The multiple-pressure method is recommended. To perform the operation a drop of lymph is first expelled on to the cleansed area. With the side of the tip of a sterile pin or needle firm pressures are made through the drop of lymph on to the underlying skin ; the pressure exerted should be sufficient to mark the skin, but not to draw blood. For a primary vaccination 10 to 12 pressures are adequate ; for revaccination 20 to 30 should be made. Excess lymph may be blotted off immediately and no dressing is necessary. This method has the advantage that it produces a minimal amount of trauma and therefore of local reaction and subsequent scarring. It probably does not give such a long-lasting immunity as the older scratch method, but since smallpox is no longer an endemic disease, the protection it affords is sufficient for most of the people in this country. When the maximum degree of protection against smallpox is desirable (in smallpox contacts), the number of insertions should be increased to two, situated at least i in. apart and the " scratch " technique used.The duration of immunity to smallpox after primary vaccination by the multiple pressure method is variable. Good " takes " to revaccination may be obtained even after the lapse of only one year. A distinction must be drawn between the results of primary vaccination and revaccination. In the former the resulting lesion does not reach a maximum until about the eighth day ; in the latter the maximum evolution is reached on the third to fifth day. This more rapid response to revaccination is one of the arguments for continuing the practice of primary vaccination in early childhood. If such a person is exposed he will respond to revaccination in the early part of the incubation period and thus be more likely to escape the illness.
Both of these reactions indicate that the individual was susceptible to small pox andhas now been rendered immune. There is a dangerous tendency in revaccination to regard no reaction or slight local reactions which reach a maximum in 24 to 48 hours as proof of immunity. Such an interpretation is unacceptable, for there may be three other explanations. First, the vaccination may have been unsatisfactorily performed ; second, the lymph may be inert; and third, the individual may be reacting merely to trauma or to the vaccine lymph. The last may be excluded fairly easily by carrying out a control vaccination with heated lymph. The others can only be excluded by performing the vaccination at least three times ; at the last insertion an entirely different site should be chosen. Such pertinacity is unnecessary in childhood. It is essential if the person is travelling to a country where smallpox is likely to be encountered and when an International Certificate of Vaccination is required.
In the event of exposure to smallpox, vaccination should immediately be performed unless there is reliable evidence of successful primary vaccination within the previous three years or successful revaccination within the previous five years. The important words in the last sentence are " reliable " and " successful ". In case of doubt, revaccinate. Owing to the risk of vaccinial encephalitis, slight as it may be, primary vaccination should not be performed in adolescents unless they have been directly exposed to smallpox ; exceptions to this general rule are nurses and medical students—for the possibility of unsuspected contact in such persons is always present.
Successful vaccination within the first four days of the incubation period may prevent an attack of smallpox.
Curative Treatment.—There is no specific treatment for smallpox. The constitutional disturbance of the prodromal stage is treated on the lines already laid down (p. i). The diet at this stage is limited to fluids, and water must be administered freely.
No chemotherapeutic substance at present available has been found to influence the maturation of the rash of smallpox from the maculo-papular to the vesicular stage, even when treatment is begun in the pre-eruptive phase. The thiosemicarbazone derivatives have not been therapeutically effective. The administration of antibiotics in adequate dosage may, however, be helpful in diminishing the amount of pus formation. The classical secondary fever caused by absorption of bacterial toxins may thus be reduced and scarring diminished. On the other hand, the patient with severe confluent smallpox goes steadily downhill—despite intensive chemotherapy—and may show evidence of in­creasing toxasmia, presumably due more to the absorption of tissue breakdown products and widespread destruction of the epidermis than to any bacterial effects.
General Management.—During the papular and vesicular stages of the eruption the regular application of an antiseptic dusting powder (boric talc dusting powder, B.P.C.) or calamine lotion (B.P.) will help to allay the skin irritation. In variola minor such treatment will usually suffice, for in this form the rash often aborts, secondary fever is usually absent and the prognosis is uniformly good.
Iced compresses applied to the face and distal parts of the limbs, and frequently changed, will be found comforting in the confluent eruption of major smallpox. Prolonged warm baths, spraying with a i : 40 solution of phenol or smearing the skin with petroleum jelly with 3 per cent. phenol are alternative methods of treatment. In children the arms may require to be splinted or the hands bandaged to prevent scratching. Chloral hydrate given orally may give some relief and facilitate sleep ; morphine aggravates skin irritation.
When the pocks begin to rupture, the patient, if not too ill, should be given a daily bath containing potassium permanganate. The offensive smell associated with confluent cases of major smallpox can be masked to some extent by sprink­ling eucalyptus oil on and around the bed. The application of starch or linseed poultices spread thinly on lint will hasten the separation of the scabs, and sub­sequent tenderness of the skin can be alleviated by the application of sterile talcum powder or zinc oxide ointment. The virus is suceptible to the action of potassium permanganate, so that painting the lesions with a i per cent. aqueous solution is effective against both bacterial invaders and the virus. Contar^ination of the ward air is thus diminished.
Owing to the presence of the eruption on the mucous membranes, the eyes, mouth, throat, nose and larynx require careful treatment. Drops of 20 per cent. sulphacetamide solution should be instilled into the eyes four-hourly. Simple ointment applied to the margins prevents the lids from sticking together during sleep. The mouth and throat must be cleansed at regular intervals ; either a i : 5,000 solution of potassium permanganate or peroxide of hydrogen diluted with two parts of water may be employed as a spray or mouth-wash. Frequent inhalations of steam, impregnated with Friar's balsam or creosote, help to alleviate laryngeal and bronchial symptoms. Dysphagia may be lessened by sucking fragments of ice or an amethocaine lozenge before each feed.
The fluid diet of the prodromal period requires to be supplemented by soft solids during the eruptive stage. Fresh fruit juice drinks sweetened with glucose must be administered freely throughout the illness.
Complications.—Severe laryngitis sometimes necessitates tracheostomy. Bronchopneumonia is a common and frequently fatal complication. Keratitis and panophthalmitis are liable to occur in severe cases, particularly if the eyes have not been carefully treated from the beginning. Myocardial damage is frequently present and strict bed rest must be enforced throughout. Hasmor-rhage, especially from the uterus, is fairly common in female patients with small­pox, and may necessitate transfusion with blood or plasma.
Convalescence.—The patient should be kept in bed until the eruption has crusted and isolation must be continued until the last crust has separated from the skin. This period varies from three weeks in mild cases to three months or longer in severe attacks. Detachment of the crusts can be hastened by warm baths and the application of starch poultices, olive oil or simple ointment. The thick skin of the palms and soles may be softened by frequent soaking in hot water, and the buried crusts picked out with a sterile scalpel. A thorough soap-and-water bath and shampoo precedes the transfer of the patient to a non-infected room in which he puts on clean clothes.
In variola minor and in mild attacks of major smallpox convalescence is usually rapid and the patient is fit for discharge from hospital or isolation as soon as he is free from infection. He may return to school or business in two to four weeks after release from isolation, but after severe attacks, several months may elapse before the patient is able to resume his normal activities.