What is malaria?
Malaria is a potentially fatal tropical disease that's caused by a parasite known as Plasmodium. It's spread through the bite of an infected female mosquito.
The infected person may have feverish attacks, influenza-like symptoms, tiredness, diarrhoea or a whole range of other symptoms.
Malaria should always be suspected if these symptoms occur within the first year of return from an infected area, and a test should be carried out to exclude the possibility of malaria as soon as possible.
Malaria is one of the leading causes of disease and death in the world. It is estimated that there are 300 to 500 million new cases every year, with 1.5 to 2.7 million deaths worldwide.
Malaria occurs extensively in tropical and subtropical regions.
It used to exist in the UK but fortunately no longer does.
In recent years, about 1,500 people have returned to Britain with malaria that they have contracted abroad - and, of these, an average of 12 die. For this reason it's important to prevent malaria in those travelling to and from the tropics.
What causes malaria?
The malaria parasite, Plasmodium, is a small, single-cell organism (protozoan) that lives as a parasite in man and a specific species of mosquito (Anopheles).
There are four different types of malaria parasite: Plasmodium falciparum is the cause of fatal malaria, while Plasmodium vivax, Plasmodium ovale and Plasmodium malariae cause more benign types of malaria. Falciparum malaria can kill, but the other forms are much less likely to prove fatal.
There are several stages in the life cycle of the parasite, and by and large these are the same for all four types.
How do you catch malaria?
Malaria is passed on by the female Anopheles mosquito biting a person who has malaria parasites in their blood.
The parasites develop in the intestine and salivary glands of the mosquito and can be passed on to other people the next time the mosquito bites.
In man, the parasite travels to the liver via the blood and then out into the bloodstream again, where it invades the red blood corpuscles (the cells which carry oxygen in the blood).
Malaria can also be passed on by blood transfusions and the use of infected needles.
Where does malaria occur?
Malaria occurs where the Anopheles mosquito lives - ie particularly in hot, humid climates.
Plasmodium falciparum is by far the most important malaria parasite in Africa.
There are also areas in: Latin America, Asia, and Oceania, where fatal malaria still occurs.
Plasmodium vivax is the most common in Asia and Latin America, including Central America.
What are the symptoms of the disease?
Normally, 10 to 15 days go by between being infected and the onset of the disease, but it may be longer if the patient has taken a preventive medicine.
On a purely practical level, the most fatal (Plasmodium falciparum) cases develop within three months of leaving the malaria region, while the forms transmitted by Plasmodium vivax and Plasmodium ovale have been recorded to appear up to 22 months later.
Malaria malariae (a rare, benign form) can survive in man for up to 30 years, luckily without causing much discomfort. This form can also be treated, provided you get the right medication.
The actual attacks of malaria develop when the red blood corpuscles burst, releasing a mass of parasites into the blood. The attacks do not begin until a sufficient number of blood corpuscles have been infected with parasites.
What are the characteristics of a malaria attack?
The attack may be what is called uncomplicated or severe.
Classic symptoms would be:
fever and shivering. The attack begins with fever, with the temperature rising as high as 40ºC and falling again over a period of several hours
a poor general condition, feeling unwell and having headaches like influenza
diarrhoea, nausea and vomiting often occur as well.
When the temperature drops, the patient often sweats profusely and feels much better. Then the same day, or one to two days later, further attacks occur with feeling generally unwell, high temperature and so on.
The attacks diminish in the course of a number of weeks, if the patient develops the ability to resist the malaria parasite. But if proper treatment is given, the fever and parasites can disappear within a few days.
But malaria can feel like mild flu. Tiredness can be the only initial symptom or to make diagnosis even more difficult, just simple diarrhoea.
If a case shifts to severe malaria, the classic symptoms above would be expected with increased drowsiness, leading to coma and associated failure of all the major organ systems.
No-one is ever completely immune to malaria, but the concept of semi or partial immunity exists, in which attacks are less severe and less likely to kill. But the price for this is multiple exposures (which kill many children).
Many people form Africa and India assume they have full or partial immunity to malaria, and these people who visit friends and relatives abroad (VFRs) compromise the largest numbers of imported malaria cases in the UK.
In severe malaria the illness may evolve with a number of complications:
low blood pressure (hypotension)
kidney failure
possible haemorrhage (bleeding)
effects on the liver (eg infectious jaundice)
shock and coma may also develop, and the condition may prove fatal.
Cerebral malaria
Severe falciparum malaria can affect the brain and the rest of the central nervous system. It's characterised by changes in the level of consciousness, convulsions and paralysis.
Blackwater-fever
In severe falciparum malaria a large number of the red blood corpuscles are destroyed. Haemoglobin (the red pigment) from the blood corpuscles is excreted in the urine, which therefore is dark and almost the colour of cola.
Late complications
If someone with a benign form of malaria is untreated, anaemia and an enlarged spleen may develop after days or weeks.
Ability to resist malaria attacks
Partial Immunity to malaria develops very slowly and is quickly lost (some estimate within 6 months of leaving the exposure area).On average one child dies every 30 seconds from malaria in these countries.
It's important to remember that nationals from malarious areas, who return home for holidays, need the same malaria protection as ordinary travellers because partial immunity develops slowly and is rapidly lost.
What can you do yourself?
There's no risk of catching malaria in the UK. But if you visit tropical and subtropical countries, it's important to investigate the chances of catching malaria.
Because the situation can change rapidly: you should talk to a doctor, travel clinic or pharmacist before planning your trip, both as regards to products for malaria prevention and also for expert advice on avoiding other dangers and diseases.
Prevention of malaria is important. If you travel to a region where malaria is prevalent, you should take preventive medication against the parasite and take whatever steps you can to avoid being bitten.
How is the disease diagnosed?
The symptoms of malaria are similar to those of many other diseases and infections that can cause fever or upset the stomach.
Therefore you should always tell your doctor if you have been abroad, especially if you've been to the tropics in the last 12 months.
The gold standard actual diagnosis is made by detecting the parasite in the blood. This is done using a special product mixed with one to two drops of the patient's blood and spreading it on a microscope slide. This is then stained and examined carefully under a microscope.
But many laboratories in the UK and overseas now use rapid antibody based screening tests.
The examination may have to be repeated if the fever has only just begun or preventive medication is to some extent keeping the numbers of the malaria parasite low.
Treatment
The treatment of malaria normally calls for admission to hospital because it may be falciparum malaria that can have a fatal outcome in only a few days or hours.
Outpatient treatment or, worse still, self-treatment of malaria is something only to be undertaken when no qualified medical help is available, ie if you develop malaria in a remote area.
The same antimalarial agents may be used to treat malaria as to prevent it. But if you have caught malaria in spite of using the correct preventive medication, a different product should be used to combat the possibility of resistant parasites.
WHAT IS DENGUE?
Dengue is a viral disease
It is transmitted by the infective bite of Aedes Aegypti mosquito
Man develops disease after 3-14 days (usually 4-7 days) of being bitten by an infective mosquito
It occurs in two forms: Dengue Fever and Dengue Haemorrhagic Fever(DHF)/Dengue Shock Syndrome(DSS).
· Dengue Fever is a severe, flu-like illness
Dengue Haemorrhagic Fever (DHF)/DSS is a more severe form of disease, which may cause death
· Person suspected of having dengue fever or DHF must see a doctor at once
SIGNS & SYMPTOMS OF DENGUE FEVER
Abrupt onset of high fever
Severe frontal headache
Pain behind the eyes(retero-orbital pain) which worsens with eye movement
Muscle and joint pains
Loss of sense of taste and appetite
Measles-like rash over chest and upper limbs
Nausea and vomiting
Minor hemorrhagic manifestations like petechae, bleeding from nose or gums may occur.
Lymphadenopathy with leukopenia and relative lymphocytosis are common. Thrombocytopenia(platelet count £ 100x103) and raised transaminases occur less frequently.
SIGNS & SYMPTOMS OF DENGUE HAEMORRHAGIC FEVER AND DENGUE SHOCK SYNDROME
Symptoms similar to dengue fever. Or history of recent fever. Illness is often biphasic beginning with fever with symptoms as in dengue. During recovery phase of fever patient’s condition worsens markedly with severe weakness, marked restlessness, facial pallor and often diaphoresis and circumoral cyanosis, severe continuous pain abdomen. Liver may be enlarged. Thrombocytopenia ( platelet count £ 100x103 ) also occurs during this phase.Haemmorhagic phenomenon are frequent and include positive tourniquet test, petechae, easy bruising, bleeding from venepuncture sites, epistaxis, bleeding from mouth & gums and skin rashes.
Frequent vomiting with or without blood. Bleeding from GI tract is an ominous sign that usually follows a prolonged period of shock. There may be signs of plasma leakage indicated by small pleural effusion or ascites. Hepatomegaly is common but is not accompanied by jaundice.
Patient may go into shock manifested by :Pale, cold or clammy skin,sleepiness and restlessness,patient feels thirsty and mouth becomes dry,rapid weak pulse and difficulty in breathing.
CLINICAL AND LABORATORY DIAGNOSIS & CASE DEFINITIONS
DENGUE FEVER:
Suspect case: Acute onset and high fever of 2-7 days duration, and two or more of the following:
Headache,retero-orbital pain, myalgia, arthralgia, rash, hemorrhagic manifestations, and leucopenia.
Probable case: Suspect case and one or more of the following:
Occurance of confirmed cases of dengue in the same place and time. Detection of IgM antibody. IgM antibody indicates current or recent infection and is detectable 6-7 days after onset of illness. If available Mc- Elisa test is more specific.
Confirmed case: Suspect or probable case and one or more of the following:
Isolation of virus or detection of viral genomic sequences. fourfold rise in titres of IgG or IgM antibody. For this at least 2 samples are to be taken- one at the time at the time of reporting to a clinic or a hospital and second shortly before discharge . The optimum interval between two samples should be 10 days. Although serological tests are simpler, they can give false positive results due to cross reaction between antibodies against dengue and other flaviviruses. Confirmatory tests are not necessary for management of cases and should be done to confirm the aetiology of the outbreak.
DENGUE HAEMMORHAGIC FEVER
· Probable or confirmed case of dengue, and
· Haemorrhagic tendencies as described under DHF.
Thrombocytopenia(platelet count £ 100x103 ).Evidence of plasma leakage due to increased vascular permeability, manifested one or more of the following: a rise in average haematocrit for age and sex ³20%, a ³20% drop in haematocrit following volume replacement compared to baseline, signs of plasma leakage indicated by pleural effusion or ascites ( demonstrated by ultrasonography or x-ray), hypoproteinemia. Slight elevation of liver enzymes, hypoproteinemia and low levels of C 3 comlement proteins are commonly observed. Prothrombin, partial thromboplastin, thrombin times may be prolonged in many cases. While a normal WBC count or leukopenia with neutrophils predominating is common initially, a relative lymphocytosis with more than 15% atypical lymphocytes is common when fever subsides.
DENGUE SHOCK SYNDROME
All the criteria for DHF, and
Evidence of circulatory failure as detailed under DSS
MANAGEMENT OF DENGUE FEVER
Early reporting of the suspected dengue fever
Management of dengue fever is symptomatic & supportive.give paracetamol but NO aspirin or brufen. Keep temp. below 390 C. In cases with severe painanalgesics or mild sedatives are to be given. Bed rest is essntial. Oral fluids and electrolyte therapy are required for patients with excessive sweating or vomiting.Follow up for any change in platelet/haematocrit. During afebrile phase(2-3 days after febrile period) check platelet/haematocrit. In convalescent phase no special instructions. Normal diet. Patients almost always recover but often have prolonged asthenia and depression.
MANAGEMENT OF DHF GRADE I & II
Duration is 2-3 days after the febrile phase. Treat on OPD/ inpatient basis. Give ORS. Check platelet/haematocrit.If Hct ³20% start IV therapy. Monitor vitals, urine output, haematocrit .
MANAGEMENT OF DHF GRADE III & IV
Duration is 2-3 days after the febrile phase. Check platelet/haematocrit. Start IV therapy. Monitor vitals, urine output, haematocrit
If Hct is increasing change IV fluid to colloidal solution preferably dextran or plasma. If Hct is decreasing from initial value, give fresh whole blood transfusion. In case of profound give IV fluid bolus one or two times. Give oxygen therapy.
EPIDEMIOLOGY
DISTRIBUTION OF DENGUE/DHF IN INDIA
Disease is prevalent throughout India in most of the metropolitan cities and towns
Outbreaks have also been reported from rural areas of Haryana, Maharashtra & Karnataka
MAGNITUDE OF THE PROBLEM
During 1996 a severe outbreak of Dengue/DHF occurred in Delhi wherein about 10252 cases and 423 deaths were reported
Till date, more then 80 outbreaks have been reported from 16 States/UTs
CAUSATIVE AGENT
It is caused by flaviviruse which has four serotypes; DEN1, DEN2, DEN3, and DEN4. Infection with one serotype provides life long immunity against that serotype but not against other serotypes. Thus people may aquire multiple dengue infections. When there are circulating antibodies against one serotype due to earlier infection and later there is infection with another serotype, it may result in dengue haemorrhagic fever / dengue shock syndrome.
PERIOD OF COMMUNICABILITY
Infected person with Dengue becomes infective to mosquitoes 6 to 12 hours before the onset of the disease and remains so upto 3 to 5 days.
AGE & SEX GROUP AFFECTED
All age groups & both sexes are affected
Deaths are more in children during DHF outbreak
VECTOR OF DENGUE/DENGUE HAEMORRHAGIC FEVER
Aedes aegypti is the principal vector of dengue / dengue haemorrhagic fever. Aedes albopictus also transmits the disease.. .
It is a small, black mosquito with white stripes and is approximately 5 mm in size.
· It takes about 7 to 8 days to develop the virus in its body(extrinsic incubation period) and transmit the disease.
Feeding Habit
Day biter with increased biting activity 2 hours after sunrise and several hours before sunset.
Mainly feeds on human beings in domestic and peridomestic situations
Bites repeatedly
Resting Habit
Rests in the domestic and peridomestic situations
Rests in the dark corners of the houses, on hanging objects like clothes, umbrella, etc. or under the furniture
BREEDING HABITS
Aedes aegypti mosquito breeds in any type of man made containers or storage containers having even a small quantity of water
Eggs of Aedes aegypti can live without water for more then one year
FAVOURED BREEDING PLACES
Desert coolers, Drums, Jars, Pots, Buckets, Flower vases, Plant saucers, Tanks, Cisterns, Bottles, Tins, Tyres, Roof gutters, Refrigerator drip pans, Cement blocks, Cemetery urns, Bamboo stumps, Coconut shells, Tree holes and many more places where rainwater collects or is stored.
CONTROL OF DENGUE/ DENGUE HAEMORRHAGIC FEVER
· Report suspected/probable cases to the health authority, eg. Zonal Health Office of MCD.No drug or vaccine is available for the treatment of Dengue/DHF. A tetravalent vaccine is under develoment and is undergoing phase I & II trials.
The control of Aedes Aegypti mosquito is the only method of choice
With early detection and proper case management and symptomatic treatment, mortality can be reduced substantially
VECTOR CONTROL MEASURES
1.PERSONAL PROPHYLATIC MEASURES· Use of mosquito repellent creams, liquids, coils, mats etc.
· Wearing of full sleeve shirts and full pants with socks
· Use of bednets for sleeping infants and young children during day time to prevent mosquito bite
2. VECTOR CONTROL
· As Aedes aegypti breeds in containers and receptacles detection & elimination of mosquito breeding sources is the most important activity.
· Management of roof tops, porticos and sunshades
· Proper covering of stored water
· Reliable water supply
· Observation of weekly dry day
5. HEALTH EDUCATION AND COMMUNITY PARTICIPATION
Impart knowledge to common people regarding the disease and vector through various media sources like T.v., Radio, Cinema slides, etc. Sensitilizing and involving the community for detection of Aedes breeding places and their elimination.
DO’S AND DON’TS
Remove water from coolers and other small containers at least once in a week
Use aerosol during day time to prevent the bites of mosquitoes
Do not wear clothes that expose arms and legs
Children should not be allowed to play in shorts and half sleeved clothes
Use mosquito nets or mosquito repellents while sleeping during day time
EARLY WARNING SIGNALS FOR DF/DHF OUTBREAK
Sudden increase in reporting of suspected cases with clutering in time and place and fitting into endemicity/ seasonality of disease.
Enhanced vector density as indicated through household larvae index/ container index / Breteau index with reference to vector mosquito.
Detection of viral activity either in vector or man.
. .
FREQUENTLY ASKED QUESTIONS
Q1. What is the difference between DF and DHF?
Ans. DHF resembles DF during initial phase of illness. However, thrombocytopenia accompanied by / followed by a rising haematocrit distinguishes DHF from DF and other diseases in the differential diagnosis, viz. malaria, leptospirosis, other arthropod born viral infections, influenza, meningococcemia and bacterial shock.
Q2. Do haemorrhagic manifestations occur only in DHF?
Ans. No. Minor haemorrhagic manifestations occur in some of the DF patients also.These cases have to be differentiated from DHF.
Q3. Why do some people have DF and others have DHF, although same flaviviruses cause both?
Ans. It is not clear with certainity why does DHF occur in some cases when the most have only dengue fever. It .is suggested that when there are circulating antibodies against one serotype due to earlier infection and later there is infection with another serotype, it may result in dengue haemorrhagic fever / dengue shock syndrome. The risk of DHF is 0.2% during the first dengue infection but it increases 10-fold during infection with a second serotype of dengue virus. However, the circulation of multiple dengue serotypes does not always produce DHF.
Q4. What is the difference in management of DF and DHF?
Ans. The manifestations and management of DF and DHF during febrile phase are the same. It is during afebrile phase of 2-3 days (critical phase) following the febrile phase that if plasma leakage occurs, it has to be managed by IV fluids ( ringer lactate/ normal saline ) in most cases. This phase lasts for 24-48 hours.
Q5. What is the role of platelet transfusion in cases of thrombocytopenia?
Ans. In most cases of DHF/DSS IV fluids / plasma expanders are adequate. However blood transfusion is indicated when haematocrit falls due to severe bleeding ( refractory shock ) and not due to fluid therapy. Fresh whole blood is preferable and volume administered should be just adequate to raise the RBC concentration to normal.
Fresh frozen plasma and / or concentrated platelets may be indicated in a few cases when disseminated intravascular coagulation (DIC) causes massive bleeding.
Q6. What is the role of insecticide spray in control of an outbreak of DF/DHF?
Ans. Residual insecticide spray in the household where a case of DF/DHF is reported and its neighbourhood kills the infected mosquitoes and thus prevents its further spread. However, generalized use of insecticides as space spray or ultra low volume spray is only of a limited value as these reduce the mosquito population only for a short period. In fact they lead to a false sense of security. Therefore, they are used as a supplement to source reduction and anti-larval measures which produce a lasting effect.
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