 |  | Clinical Guidelines and Treatment Manual (MSF, 1993, 319 p.) | ||
 |  | Chapter 8 - Viral infections | ||
|  | Measles | ||
| | Poliomyelitis | ||
| | Arbovirus diseases | ||
| | Rabies | ||
| | Hepatitis | ||
| | A.I.D.S. and infection by VIH | ||
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- Also called rubeola and morbilli, it is one of the commonest childhood infectious exanthems. Among children in developing countries it is a serious illness with high mortality, especially when associated with malnutrition. Measles often precipitates acute malnutrition. Prevention by universal immunization of young children must always be a high priority.
- Measles is never subclinical, however recent studies have shown that the severity of the disease is related to the infective dose of virus. Crowding tends to increase mortality.
Clinical features
Figure 6
Complications
These must be looked for in all patients.
- Serious signs: persistent fever with darkening of the rash ("black measles") and subsequent desquamation.
- Stomatitis: compromises sucking and eating.
- Laryngitis: distinguish a benign prodromal laryngitis from that due to a secondary infection, which may be severe.
- Croup and otitis media.
- Bronchopneumonia: usually severe; gram negatives or staphylococcus.
- Diarrhea: either due to virus or from a secondary infection.
- Vitamin A deficiency: keratoconjunctivitis. Measles increases the con-sumption of vitamin A and often precipitates xerophthalmia.
- Encephalitis: caused by the measles virus itself; it occurs on about the 5th day of the rash.
- Malnutrition: precipitated by anorexia, stomatitis, fever, vomiting, diarrhea and other complications. Also important are frequent harmful cultural taboos that impose fasting upon a child with measles.
Treatment
(dispensary)
- Active case-finding during epidemic, if practical (home visits).
- Treat the fever.
- Keep well hydrated.
- Observe closely for complications.
- Give prophylaxis against conjunctivitis: drops or ointment.
- Give prophylaxis against xerophthalmia: vitamin A
|
Infants: |
100,000 IU in single dose on day 1, day 2 and day 8 |
|
After 1 year: |
200,000 IU in single dose on day 1, day 2 and day 8 |
- Encourage good oral hygiene.
- Maintain adequate protein-calorie intake: educate mothers (especially if cultural taboos against feeding exist), continue breast feeding, provide supplementary feeding if available (but do not admit to a feeding center until after infectious period).
- Antibiotics are often given prophylactically:
penicillin V
(PO): 100,000 IU/kg/d divided in 3 doses x 5 days
or
cotrimoxazole (PO);
60 mg of SMX/kg/d divided in 2 doses x 5 days
(dispensary - hospital)
- Treat secondary infections with antibiotics:
ampicillin: 100 mg/kg/d divided in 3 doses or (per os, IM or IV according chloramphenicol: 75 mg/kg/d divided in 3 doses to gravity x 7-10 days) or cotrimoxazole: 60 mg of SMX/kg/d divided in 2 doses
-Give supportive therapy for meningoencephalitis:
Adequate
hydration, good nursing, nasogastric feeding and control convulsions with
diazepam.
Prevention
- Education of mothers must be part of the MCH program.
- Immunization:
· A single injection gives good protection. Ideally should be given at the age of 9 months, but is often given later.
· Measles immunization is one of the highest priorities in refugee settings and other situations where crowding, poor hygiene and precarious nutritional status combine to encourage both transmission and the emergence of complications.
· There is an Oxfam/WHO measles immunization kit that is designed for emergency situations. Newly arrived refugee populations should be immunized during the first days of the emergency and all new arrivals should be immunized on entering. The target age-group is children from 9 months to 12 years (up to 5 years if resources are very scarce).
- Acute infection due to the three strains of poliovirus affecting infants and young adults. It is endemic in developing countries but may occur in seasonal epidemics among non-immune persons. Transmission is feco-oral.
- Polio should disappear when immunization is universal. A very high proportion of cases are asymptomatic and these healthy carriers are the reservoir of infection: only 0.1% of infections give rise to paralysis. Polio occurs endemically in developing countries but seasonal epidemics can also occur.
Clinical features
- Febrile flu-like illness, often with diarrhea.
- Sometimes aseptic meningitis.
- Paralytic forms: paralysis is of sudden onset (often noted on waking in the morning), asymmetrical and hypotonic. It is associated with fever, hyporeflexia, risk of respiratory paralysis and eventual muscle wasting.
Treatment (hospital)
Is supportive only:
- Treatment of the fever and diarrhea.
- Rest, nursing care
for paralytic cases.
- Physiotherapy once signs have stabilized.
Prevention
- Immunization with live attenuated trivalent oral polio
vaccine
(OPV) with first dose at birth (new WHO recommendation) and then 3
more doses at the 6th, 10th and 14th weeks.
- Salk injectable killed vaccine at the 6th, 10th and 14th weeks.
- Theorically, boosters 1 year later and 5 years after that.
Public health measures
Community-level management:
- A paralytic case signifies that the virus is in circulation.
- Confirm the diagnosis serologically (rising titres).
- The immunization status of the community should be determined: date of the most recent program, coverage...
- If necessary, plan and implement a mass immunization program for children aged from 3 months to 5 years and carry out an "outbreak investigation".
Viral illnesses that usually have an animal reservoir and are trans-mitted to humans by mosquito vectors. They occur either sporadically or in epidemics.
Clinical features
Different viruses have different manifestations; however there are four main syndromes:
- Flu-like viral illness: e.g. dengue fever (SE Asia and the Pacific).
- Encephalitis: fever, neurological signs, convulsions, coma, sometimes meningism with a clear CSF. E.g. Japanese B encephalitis (SE Asia).
- Hepatorenal syndrome: fever, jaundice, oliguria, albuminuria, sometimes hemorrhages. E.g. yellow fever (West Africa, South America).
- Hemorrhagic fever: clinical picture of severe dengue fever plus shock and hemorrhagic manifestations in skin and mucosae. E.g. dengue hemorrhagic fever (usually only seen in children in SE Asia); also diseases such as Lassa fever, Ebola and Marburg virus, which have caused fulminant and deadly epidemics in Africa.
Treatment (hospital)
There is no causal therapy. Treatment is supportive.
Prevention
- Immunization: only a vaccine for yellow fever is available. A single injection protects for 10 years.
- Personal protection: mosquito nets, adequate clothing.
- Vector control: sanitation, destruction or management of vector breeding sites (e.g domestic refuse, water containers for urban AEdes aegypti, the vector of yellow fever).
- Epidemic management:
· Confirm the diagnosis: virological and serological studies in the nearest reference laboratory. One should collect detailed clinical and epidemiological information.
· Alert the local authorities.
· Plan control measures with the local authorities: vector control, public education and an immunization campaign.
Viral zoonosis transmitted to humans in the saliva of an
infected animal.
Innoculation can be by:
- bite: dog, cat, wild animal, vampire bats (South
America),
- licking open skin lesions: cats, dogs, goats...
Principles of preventive tberapy
- The risk of exposure to rabies is higher in developing countries because of the high prevalence of the disease in stray animals.
- Clinical rabies in humans is invariably fatal but can be prevented with vaccine and antiserum after exposure.
- The incubation period in humans is from 2 weeks to several months depending on the severity and site of innoculation.
- An infected animal sheds rabies virus in its saliva before it develops signs of disease (14 days for dogs and cats).
Table 15
- There are two types of exposure:
· Benign: contact of saliva with scratches on the skin; minor bites on the trunk or proximal limbs.
· Serious: contact of saliva with mucus membranes; bites on the face, head, neck, hands, feet, genitals; and bites from a wild animal.
Management of a person exposed to rabies (dispensary)
AFTER BITE
- Wash wound with soap, rinse, then dry thoroughly.
- Clean wound with chlorhexidine-cetrimide or other antiseptic and do not suture.
- Give tetanus prophylaxis.
- Capture and observe the animal for 15 days.
- Treatment:
· antirabies serum (Pasteur): prepared from horse
immunoglobin.
· rabies vaccine (Pasteur): human diploid cell vaccine
(HDCV).
- Note: the old vaccines (e.g. duck embryo) require several injections (7-14) and have allergic and neurological complications.
INDICATIONS FOR VACCINATION
- Depends on the condition of the animal at the time of the bite and after 15 days.
- There are two regimens:
· Benign exposure: simple rabies vaccination 1 dose (SC or IM) on day O (the start of the schedule), day 3, day 7, day 14, day 30 and day 90.
· Serious exposure: serum + vaccination Day O (as soon as possible after the bite): give serum 20-40 IU/kg IM Then Day 1, 8, 15, 30 and 90: give 1 dose of rabies vaccine.
Preventive measures for exposed personnel
Personnel who may be exposed to rabies (e.g. veterinarians, technicians) should be given 3 doses of rabies vaccine (HDCV) on days 1, 7, 21 or 28 and a booster dose after 6 months.
Table
16
Several viral infections come under the heading viral hepatitis, each having its own epidemiology, clinical characteristics, immunology and prognosis. Hepatitis A, B, D and E occur in the tropics. The geographic distribution of hepatitis C is not yet known. All hepatitis, when they resolve, result in life long immunity, but not shared immunity.
The old terminology, non A-non B (A like-B like) has now been changed to hepatitis C and E. The "defective" virus D needs the presence of virus B to develop.
Principle characteristics are summarized in table 17.
Clinical features
ACUTE HEPATITIS
Nausea, fever, fatigue, abdominal discomfort, followed by the appearance of jaundice having an element of biliary obstruction, dark urine and stools more or less pale.
SUBCLINICAL INFECTION
Mild or anicteric infection is the most common but exposes the sufferer to the same risks.
FULMINANT HEPATITIS
Severe acute infection that leads to necrosis and liver failure. It is associated with high mortality.
CHRONIC ACTIVE HEPATITIS
May lead to cirrhosis and eventually hepatoma.
Treatment
- Symptomatic: rest, caution in prescribing analgesics (ea. acetyl salicylic acid, paracetamol), correct but not specific diet and hydration.
- Avoidance of corticosteroid therapy. Several medications are contraindicated.
Vaccination
Plan to include anti-B vaccine in the Expanded Program of Immunization (EPI).
Table
17
AIDS, or Acquired Immune Deficiency Syndrome,is the most serious form, the end stage of infection by HIV (Human Immune-deficiency Virus). The virus attacks the immune system by infecting and then destroying the T4 lymphocytes.
Infection by HIV develops as a function of time,
schematically:
- Incubation period
From infection by the virus to the appearance of specific anti-HIV antibodies, lasts on average 6 weeks, sometimes marked by a non specific febrile syndrome (pseudo influenza syndrome).
- Asymptomatic period
This is the seropositive phase which can last years. The diagnosis depends on the detection of specific anti-HIV antibodies in the blood. On average, 50 % of seropositives progress to AIDS in 10 years (with actual decline).
- Symptomatic period
The immune deficiency syndrome is manifested clinically, it is the clinical AIDS phase. The pre-AIDS syndrome which was at a certain time defined by the term ARC (AIDS-related complex), is les and less recognised as a physiopathological entity. This is why there is no mention made of it here.
Epidemiology
HIV/AIDS infection is pandemic, occurring in epidemic form on 5 continents: however, not all populations are uniformly affected in one country or another or in the midst of the same country.
PREVALENCES
- Seropositives
In April 1991, WHO estimated that 8-10 million adults in the world had been infected by the virus since the beginning of the epidemic. Of these more 60 % were in Sub-Saharan Africa and around 1 million were children.
- Clinical AIDS
In April 1991, WHO estimated the number of clinical AIDS cases to be 1.5 million since the beginning of the epidemic (345,000 notified cases), 500,000 cases were children.
- Serotypes
Two serotypes have been identified: HIV 1 and HIV
2.
HIV 1 is the most widespread.
HIV 2 is particularly found in West
Africa and spreads less rapidly than HIV 1. However, the modes of transmission
and the clinica1 picture do not differ from one serotype to the other.
HIV TRANSMISSION
- Sexual transmission
During improtected homosexual and heterosexual relations. 70 % of the world's HIV infections result from heterosexual transmission.
- Blood transmission
By transfusions, contaminated surgical instruments, contaminated syringes and needles, by contact of even a minimal wound with contaminated blood (surgery or childbirth delivery without gloves, injury or prick with a needle or instruments contaminated with infected blood).
- Materno-faetal transmission
During pregnancy or delivery.
Note: transmission breast feeding is possible: nevertheless, the relationship between benefits and risks is such tnat WHO continues to recommend this form of feeding.
- HIV is not transmitted by saliva, mosquitoes, air, water, food, skin contacts, clothing, cooking utensils, the movement of general daily life.
Table 18
Projections
- Groups at risk: heterosexual transmission is the origin of 70 % of cases of infection in 1991, the groups at risk for the decade 1990-2000 will be heterosexual populations with multiple partners.
- Geography: 90 % of cases will survive in developing countries, Sub-Saharan Africa, Asia and Latin America.
Clinic factors
Table 19
This exclusively clinical definition is intended for developing countries lacking laboratory facilities (culture and/or histology). It is, above all, an indispensable tool in the surveillance of AIDS (notification of cases) and an elaborate clinical tool permitting clinicians to make a diagnosis with the maximum precision.
Table 20
Serological diagnosis of HlV infection/AIDS
In conditions in the field, the diagnosis of HIV infection in the asymptomatic adult can only the serological, i.e. the presence of specific anti-HIV antibodies in the blood is the sign of infection.
SEROLOGICAL TESTS
Table 21
In practice, the serological diagnosis of suspected AIDS is of no therapeutic interest. It can be justified for certain suggestive clinical tables of AIDS, but without satisfying the criteria of WHO clinical definition.
PRINCIPLES OF SEROLOGICAL DIAGNOSIS
To prescribe a serological test and announce the result negative or positive, for an HIV test, it must be combined with all the following conditions:
1. The patient must have received appropriate information about the consequences of a positive result and have given prior permission to be tested for anti-HIV antibodies.
2. Positive results from a blood sample must be confirmed by Western-Blott.
3. The seropositive individual must be able to benefit from further medical care and advice +++.
4. Confidentiality.
Treatment of HIV infection and AIDS
ANTIRETROVIRAL THERAPY
The only molecule in current commercial production is AZT (Azidothymidine). Its cost (2,000 - 3,000 US$/year) and the necessary techniques for therapy prevent, at present, its general use in developing countries.
TREATMENT OF OPPORTUNIST OR ASSOCIATED INFECTIONS (WHO GUIDELINES)
See tables 22a, 22b and 22c.
Table 22a
Table 22b
Table 22c
Prevention of transmission of HIV infection and AIDS
DURING SEXUAL INTERCOURSE
Systematic use of condoms is the only reliable prevention.
DURING TRANSFUSION
Strict respect for the indications for transfusion and systematic serological sampling of blood donors constitute the essential principals for the safety of transfusions.
See M.S.F. practical guide: "Practical transfusion in isolated surroundings - prevention of transmission of HIV"
IN MEDICAL FACILITIES
The prevention of the transmissin of HIV infection in the course of treatment takes place by reinforcement and strict respect for classical measures of hygiene:
- correct sterilization and disinfection of medical
material,
- avoidance of injections which are not strictly necessary,
-
precautions to avoid accidental contamination with soiled instruments,
-
precautions to avoid contact with potentially infected biological liquids.
See M.S.F. practical guide: "Recommendafions to prevent HIV transmission in health care facilities in developing countries "
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