Smallpox | Smallpox virus

Smallpox

Smallpox is a highly contagious disease caused by the smallpox virus, an orthopoxvirus. Case fatality rate is about 30%. Natural infection has been eradicated. The main concern for outbreaks is from bioterrorism. Severe constitutional symptoms and a characteristic pustular rash develop. Treatment is generally supportive and potentially with antiviral drugs. Prevention involves vaccination, which, because of its risks, is done selectively. read also about monkey pox

No cases of smallpox have occurred in the world since 1977 because of worldwide vaccination. In 1980, the World Health Organization (WHO) recommended discontinuation of routine smallpox vaccination. Routine vaccination in the US ended in 1972. Because humans are the only natural host of the smallpox virus and because the virus cannot survive > 2 days in the environment, WHO has declared natural infection eradicated.

 

Concerns about bioterrorism using smallpox virus from retained research stores or even from synthetically created virus raise the possibility of a recurrence (see Biological Agents as Weapons and Centers for Disease Control and Prevention [CDC]: Smallpox/Bioterrorism).

 

Pathophysiology of Smallpox

There are at least 2 strains of smallpox virus:

·         Variola major (classic smallpox), the more virulent strain

·         Variola minor (alastrim), the less virulent strain

Smallpox is transmitted from person to person by;

·         Inhalation of respiratory droplets or,

·         Less efficiently, by direct contact.

·         Contaminated clothing or bed linens can also transmit infection.

 The infection is most communicable for the first 7 to 10 days after the rash appears. Once crusts form on the skin lesions, infectivity declines.

The attack rate is as high as 85% in unvaccinated people, and infection may lead to as many as 4 to 10 secondary cases from each primary case. However, infection tends to spread slowly and mainly among close contacts.

The virus invades the oropharyngeal or respiratory mucosa and multiplies in regional lymph nodes, causing subsequent viremia. It eventually localizes in small blood vessels of the dermis and the oropharyngeal mucosa. Other organs are seldom clinically involved, except for occasionally the central nervous system, with encephalitis. Secondary bacterial infection of the skin, lungs, and bones may develop.

 

Symptoms and Signs of Smallpox

Variola major symptoms

Variola major has a 10- to 12-day incubation period (range 7 to 17 days), followed by a 2- to 3-day prodrome of fever, headache, backache, and extreme malaise. Sometimes severe abdominal pain and vomiting occur. After the prodrome, maculopapular lesions develop on the oropharyngeal mucosa, face, and arms, spreading shortly thereafter to the trunk and legs. The oropharyngeal lesions quickly ulcerate. After 1 or 2 days, the cutaneous lesions become vesicular, then pustular. Pustules are denser on the face and extremities than on the trunk, and they may appear on the palms. The pustules are round and tense and appear deeply embedded. Skin lesions of smallpox, unlike those of chickenpox, are all at the same stage of development on a given body part. After 8 or 9 days, the pustules become crusted. Severe residual scarring is typical. see also monkey pox symptoms and signs

 

Case fatality rate is about 30%. Death results from a massive inflammatory response causing shock and multiple organ failure and usually occurs during the 2nd week of illness.

 

About 5 to 10% of people with variola major develop either a hemorrhagic or a malignant (flat) variant.

The hemorrhagic form is rarer and has a shorter, more intense prodrome, followed by generalized erythema and cutaneous and mucosal hemorrhage. It is uniformly fatal within 5 or 6 days.

 

The malignant form has a similar, severe prodrome, followed by development of confluent, flat, nonpustular skin lesions. In survivors, the epidermis frequently desquamates.

 

Variola minor symptoms

Variola minor results in symptoms that are similar but much less severe, with a less extensive rash.

 

Case fatality rate is < 1%.

 

Diagnosis of Smallpox

Polymerase chain reaction (PCR)

Electron microscopy

Unless laboratory exposure is documented or an outbreak (due to bioterrorism) is suspected, only patients that fit the clinical case definition for smallpox should be tested because of the risk that test results may be falsely positive. An algorithm for evaluating the risk of smallpox in patients with fever and rash is available on the CDC web site (CDC Algorithm Poster for Evaluation of Suspected Smallpox).

 

Diagnosis of smallpox is confirmed by documenting the presence of variola DNA by PCR of vesicular or pustular samples. Or the virus can be identified by electron microscopy or viral culture of material scraped from skin lesions and subsequently confirmed by PCR. Suspected smallpox must be reported immediately to local public health agencies or the CDC at 770-488-7100. These agencies then arrange for testing in a laboratory with high-level containment capability (biosafety level 4).

 

Treatment of smallpox is generally supportive, with antibiotics for secondary bacterial infections. The antiviral drug tecovirimat was approved by the US Food and Drug Administration (FDA) in 2018 ( 1) and, in June 2021, the FDA approved brincidofovir (CMX 001) for treatment of smallpox. Both approvals were based on experimental studies and, although their effectiveness against smallpox in humans is unknown,

 

Isolation of people with smallpox is essential. In limited outbreaks, patients may be isolated in a hospital under airborne transmission precautions in an airborne-infection isolation room. In mass outbreaks, home isolation may be required. Contacts should be placed under surveillance, typically with daily temperature measurement; if they develop a temperature of > 38° C or other sign of illness, they should be isolated at home.

 

Risk factors for complications include extensive skin disorders (particularly eczema), immunosuppressive diseases or therapies, ocular inflammation, and pregnancy. Widespread vaccination is not recommended because of the risk.

 

 

1. CORONA VIRUS
2. MONKEY POX
3. VAGINAL DRYNESS
4. FIBROID
5. INFERTILITY
6. OVULATION CYCLE
7. OVARIAN CANCER
8. VAGINAL BACTERIA
9. MALE INFERTILITY
10. BEST DAYS OF CONCIEVING
11. MUCUS AFTER OVULATION
12. FOODS FOR ERECTILE FUNCTIONS
13. PREGNANCY ANEMIA
14. DO AND DONT DURING PREGNANCY
15. ERECTILE DYSFUNCTION
16. U.T.I IN PREGNANCY
17. STROKE RISK
18. EAT THIS NOT THAT
19. HOOKWORMS INFECTION
20. OMEGA 3 BENEFITS
21. FASTING
22. WEIGHT LOSS TIPS
23. vitiligo
24. ABORTION
25. DENGUE VIRUS
26. EBORA VIRUS
27. FEVER
28. URINARY TRACT INFECTION
29. HOSPITAL INFECTIONS
30. WEST NILE VIRUS
31. YELLOW FEVER
32. EYE DISEASE
33. ZIKA VIRUS
34. STRESS
35. IRON DEFFICIENCE
36. INSOMNIA (SLEEPING PROBLEMS)
37. HEART PROBLEMS
38. COMPONENTS OF BLOOD
39. BLOOD DISORDER
40. LABORATORY TEST OF BLOOD DISORDER
41. BONE MARROW EXAMINATION
42. BLOOD ANEMIA
43. ANIMAL BITES
44. EYE BURN
45. CHOCKING
46. HEAT STROKE
47. SMOKE EFFECTS
48. SNAKE BITE
49. MALARIA VACCINE
50. BEST WAY TO SLEEP A CHILD
51. CHILD FEVER REDUCING
52. ELEPHANTIASIS
53. WOMEN BEARDS
54. DATES
55. PAPAYA FRUITS