Chicken pox is an acute and highly infectious disease caused by a virus. It is characterized by itchy and painful vesicular (fluid-filled) rashes or blisters that later form scabs, which are scattered all over the body and may be accompanied by fever and malaise (feelings of unwell).
The disease is used to be one of the classic childhood diseases, but its less common since the introduction of the chicken pox vaccines. It has a world-wide distribution and occurs in epidemic and endemic forms.
THE CAUSATIVE AGENT
Chicken pox is caused by the virus called the Varicella-Zooster (V-Z) virus, a member of the herpes virus family which also causes herpes zoster (shingles) in adults. Both Chicken pox and herpes zoster are now regarded as different host responses to the same etiological agent.
Inoculation of zoster vesicle fluid into children produces Chicken pox and children who have recovered from zoster virus related infections are resistant to variciella.
The V-Z virus also called “Human (alpha) herpes virus 3” causes Chicken pox as the primary infection. Recovery from a primary infection is commonly followed by establishment of a latent infection in the cranial nerve sensory ganglia and spinal dorsal root ganglia and this may stay for decades without clinical signs and symptoms.
There could be a reactivation of the virus in cases of depressed immunity, often with increasing age, or the use of immune suppressive therapy like steroids for a long period of time.
SOURCE OF INFECTION:
Usually, the infection is spread by a case (patient) with Chicken pox and rarely from a patient with herpes zooster. The virus occurs in the oropharyngeal secretion and lesions (wounds) of the skin and mucosa (lining of the soft tissue) and can be isolated from vesicle fluids during the first 3 days of illness. The scabs later formed are not infectious. Chicken pox can be spread very easily to others, could be from touching the fluids from a Chicken pox blister or if someone with the disease coughs or sneezes near you, even mild form of the disease is contagious.
The virus is extremely labile and its unlikely that formite play significant role in the transmission. Overcrowding favours transmission. A person with Chicken pox becomes contagious one or two days before the rash appears and four to five days after the rash, up to the period when the blisters have crusted by which they are no longer infectious.
The vesicles may later become pustules (pus filled), but the virus tend to die out before this time. The rate at which members of a household contract the disease is very high up to 90 percent. (Secondary attack rate), hence the disease is highly communicable.
INCIDENCE AND RISK FACTORS:
Chicken pox is mostly a disease of children, usually less than 10 years. Sometimes, up to 14 years. The disease progression is usually mild, although, sometimes, serious complications could arise.
The disease can be severe in normal adults and older children; in younger children only if they have depressed immunity because of illness or the use of medications such as steroids or chemotherapy.
One attack gives a durable immunity and second attacks are rare. Infections during pregnancy present a risk for the fetus and neonate because the virus crosses the placental barrier- a condition called congenital vermicular.
For infants whose mother have had Chicken pox and have received the vaccine, thereby developing the antibodies (I g G clan of antibodies) against the disease, they are not likely to catch it, and if they do, their cases are often mild because of the protective nature of the antibodies against vermicelli.
The cell mediated immunity appears to be important in recovering from V-Z infection and in protection against reactivation of the latent V-Z virus. No age however, is exempted in the absence of immunity.
Symptoms vary from mild illness with only a few scattered rashes, to a severe fertile illness with widespread rash. Infection is unapparent in an estimated 5 percent of susceptible children and in majority of cases, the disease tend to be mild and typical.
The symptoms of Chicken pox may be divided into two stages:
Pre-eruptive stage (before the rash appears):
This is the prodromal stage and its onset is sudden. It is characterized by:
- Mild or moderate fever
- Stomach ache
- Pain in the back
- Shivering and malaria.
This stage is very brief, lasting about 24 hours; therefore it requires a high index of suspicion to recognize it because other diseases like malaria and fever may also display like this. It is usually more severe in older children and adults and may last for 2-3 days.
THE ERUPTIVE STAGE (after the appearance of the rash):
The rash occur after the prodromal stage symptoms.
It is symmetrical.
It first appear on the trunk (between the neck and hip) and scalp and very abundant, then on the face-arms-legs where they are less abundant.
The mouth, pharynx, vagina and eyelids are involved, so also is the axilla (armpit).The flexor surfaces are mostly affected i.e. T he inner surfaces of the elbow and knee joints.
The rash advances rapidly in different stages viz: macule (flat surface)----> papule (raised surface) -- >vesicles (fluid filled)----> scab (crusted), and it is pleomorphic i.e. the different stages are evident at a given time because the rash appears in successive crops. An area of inflammation is seen around the vesicles, looking like “dew drops” on the skin, which are the first to attract attention. Usually they are not unbilicated. Most pox will not leave scars unless they become infected with bacteria from scratching.
The Chicken pox rash appears about 10-21 days after coming in contact with someone who has the disease, could be shorter, 14-16 days.i.e (incubation period)
The average child develops 250-500 small, itchy, fluid-filled blisters over red spots on the skin. Children with skin problems like eczema may get thousands of blisters. Fever does not run high but shows exacerbation with each fresh crop of rash.
Some children who have had the vaccine will still develop a mild case of Chicken pox. They recover much more quickly usually, and have only a few pox (fewer than 30 but are harder to diagnose. However,they can still spread Chicken pox to others.
These are what your health care provider sees and affirms that it’s a case of Chicken pox. Small blisters on the scalp usually confirms diagnosis. He can ask questions about the person’s medical history. Laboratory test can also help confirm diagnosis if need be.
CONTROL AND TREATMENT:
Being a viral illness, there is no specific treatment. Viral infections usually run their course;treatment is based on treating the symptom as it evolves and also keeping the patient as comfortable as possible.
1. Keep the fingernails short
2. Wear cool, light clothing; avoid wearing rough clothing particularly wool over itchy areas.
3. Avoid prolonged exposure to extremes of heats and humidity.
4. Apply a soothing moisturizer to soften and cool the skin after bathe.
5. Take lukewarm bathe using little soap and rinse thoroughly, do not hard-sponge.
6. You can apply hydrocortisone cream on itchy areas.
7. You can also take antihistamines like piriton (at night) or loratidyn to reduce itching.
8. Avoid overcrowding.
- Do not give Aspirin (Associated with Reye’s syndrome) or Ibuprofen (associated with severe infection). Acetaminophen may be used.
- A child with Chicken pox should not return to school or play with other children until all chicken pox sores have crusted over or died out, likewise adults that would be returning to work.
Medications that fights the Chicken pox virus are available, but not given to everyone. These medications are commenced within 24 hours of the rash for effectiveness to eligible persons.
They include several Antiviral compounds like
i. They must be prescribed strictly by your health care provider. Acyclovir for example, can prevent development of systemic diseases in varicella infected immunosuppressed patient and can halt the programming of zoster in adults.
1. Adults and teens who are at risk for more severe symptoms
2. Those with skin diseases as eczema or recent sunburn, lung condition (as Asthma) or who have recently taken steroids.
3. Persons in the same household who also developed Chicken pox and they usually develop more severe symptoms
Usually, a person recovers without complication. As said earlier, once the disease is contracted, the virus remains dormant in the body for a lifetime; about 1 in 10 adults will have shingles (herpes zoster) when the virus re-emerges during a period of time.
These are rare, but include;
1. Bacterial encephalitis
2. Reye’s syndrome
5. Transient Arthritis
6. Cerebella ataxia (involves a very unsteady walk)- may develop during the recovery phase or later.
Chicken pox is airborne and very contagious before the rash even appears; it is therefore difficult to avoid.
The use of vaccine is very important and its part of a child’s routine immunization schedule. It usually prevents the disease completely or makes the illness very mild, especially when given early enough.
DR. E.I. OKEREKE