Smallpox diagnosis

To assist physicians in evaluating patients with suspicious rash illnesses, the CDC has developed three major and five minor criteria that physicians can use in determining whether patients are at high moderate or low risk for smallpox (http //www. bt.cdc.gov/agent/smallpox/diagnosis/pdflspox-poster-lst-half.pdf. The three major criteria are ... 

Nakano JH. Evaluation of virological laboratory methods in smallpox diagnosis. Bull WHO. 1973 48 529-534. 

Suggested Alternatives for Differential Diagnosis Other causes of pneumonia, typhoid fever, tuberculosis, plague, anthrax infection, smallpox. 

Suggested Alternatives for Differential Diagnosis Smallpox, pseudocowpox/paravaccinia, Varicella-zoster, tularemia, plague, parapox virus, Eczema herpeticum. 

CDC Case Definition An illness with acute onset of fever >101°F followed by a rash characterized by firm, deep seated vesicles or pustules in the same stage of development without other apparent cause. Clinically consistent cases are those presentations of smallpox that do not meet this classical clinical case definition (1) hemorrhagic type, (2) flat type, and (3) variola sine eruptione. Laboratory criteria for diagnosis is (1) polymerase chain reaction (PCR) identification of variola DNA in a clinical specimen, or (2) isolation of smallpox (variola) virus from a clinical specimen (Level D laboratory only confirmed by variola PCR). 

How many people would have to get smallpox before it is considered an outbreak One suspected case of smallpox is considered a public health emergency. Smallpox surveillance in the United States includes detecting a suspected case or cases, making a definitive diagnosis with rapid laboratory confirmation at CDC, and preventing further smallpox transmission. A suspected smallpox case should be reported immediately by telephone to state or local health officials. They should immediately obtain advice regarding isolation of the patient or patients, and on laboratory specimen collection. State or local health officials should notify CDC immediately at (404) 639-2184 or (404) 639-0385 if a suspected case of smallpox is reported. 

Each state varies considerably as to which diseases must be reported, to whom the information is reported, who is required to report, and what information they are required to provide concerning the patient. For example, whereas almost all states require reporting of new cases of anthrax, either within 24 hours or sometimes beyond 24 hours of diagnosis, less than half of the states require any reporting of new cases of smallpox (Horton, Misrahi, Matthews, Kocher, 2002). (For a summary of the different state laws on the reporting of diseases that might possibly be associated with a bioterrorist attack, see Horton et ah, 2002). 

Laboratory diagnosis of smallpox is essential and specimens should be obtained by people vaccinated against... 

Once the attack and the agent have been identified through clinical diagnosis, public health officials will provide information about the symptoms and instruct you to get medical treatment immediately if you display any of them. Anthrax can be prevented or cured with aggressive use of antibiotics. Although smallpox has no cure, medical care increases the chances of survival. 

People previously vaccinated for smallpox can develop a febrile illness after exposure to a smallpox case. Typically, fever begins suddenly, reaches 39°C and is associated with headache and occasionally backache. Symptoms resolve within 48h. Serologic studies in these patients have suggested the diagnosis of variola sine eruptione by demonstrating a significant rise in variola antibody titers following the illness (25). 

The discovery of even one case of smallpox in the world would be an international medical and public health emergency. Therefore, the appropriate diagnosis is essential. Physicians who have never seen smallpox might confuse smallpox with varicella... 

Patients having a febrile prodrome and either one other major criterion or at least four minor criteria are at moderate risk for smallpox. For patients at moderate risk, physicians should alert infection control and immediately institute contact precautions and respiratory isolation. If possible, they should obtain dermatology and/or infectious disease consultation and obtain digital photographs of the lesions. Given a moderate risk situation, the appropriate clinical diagnosis is essential, and physicians must rule out varicella or complication of vaccinia (smallpox vaccine). Therefore, for moderate risk patients, the history is essential, specifically the history of clinical varicella infection, history of vaccination for varicella and history of possible exposure to vaccinia (smallpox) vaccine. 

After an aerosol release of smallpox, public health authorities will make vaccine supplies available to affected communities. Postexposure vaccination is effective in preventing infection or lowering mortality up to 4 days after exposure. Physicians should give the vaccine to suspected cases to ensure that a mistaken diagnosis does not place patients at risk for smallpox. An emergency vaccination program should also include (26) ... 

This reassuring, thorough resource undoubtedly will prove a comfort for many readers and, in the case of a bioterrorist attack, has the potential to save countless lives. Color photo insert of organisms and, to aid in diagnosis, of skin rashes (comparing, for instance, smallpox to chickenpox). 

Ricketts TF. The Diagnosis of Smallpox. London, England Cassell 1908. 

World Health Organization. Guide to the Laboratory Diagnosis of Smallpox for Smallpox Eradication Programs. Geneva, Switzerland World Health Organization 1969. 

Mitra AC, Sarkar SK, Mukherjee MK, Chakravarty MS. Evaluation of the precipitation-in-gel reaction in the diagnosis of smallpox. Bull WHO. 1973 49 555-558. 

There is no specific treatment for smallpox. Supportive therapy should be started initially as directed by the clinical condition of the casualty. If a diagnosis of smallpox is suspected, the case should be discussed urgently with a consultant microbiologist. Isolation and appropriate barrier precautions should be taken, including the wearing of facemasi . If a deliberate aerosol release is suspected, PPE must be worn and appropriate decontamination carried out with safe disposal... 

A designated local Smallpox Diagnostic Expert (SDE) should be contacted for all suspected cases. If the diagnosis of smallpox remains likely the SDE will alert the Smallpox Management and Response Team (SMART) which will take over further investigation and treatment of the patient, and organise national responses. 

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