Malaria facts, by WHOGolden RulesTravellers and their advisers should note the four principles of
malaria protection:
A. Be Aware of the risk, the incubation
period, and the main symptoms.
B. Avoid Being bitten by mosquitoes,
especially between dusk and dawn.
C. Take antimalarial drugs (Chemoprophylaxis)
to suppress infection when appropriate.
D. Immediately seek Diagnosis and treatment
if a fever develops one week or more after entering an area where there is a
malaria risk, and up to 3 months after departure. Malaria exposed traveller’s prevention kit includes:1. 1 impregnated mosquito net (pre-impregnated
or impregnated on site using Permethrin, Deltamethrin or Etofenprox)
2. N 50 ml bottles of DEET based repellent – N : 1 bottle per 10
days stay
3. 1 bottle of permethrin spray
to impregnate clothes
4. 1 kit including diagnostic
test and self-treatment, preferably using Coartem® / Riamet® General considerationsMalaria is a common and
life-threatening disease in many tropical and subtropical areas. It is
currently endemic in over 100 countries, which are visited by more than 125
million international travellers every year.
Each year many international travellers fall ill with malaria while visiting countries where the disease is endemic, and well over 10 000 fall ill after returning home. Fever occurring in a traveller within three months of leaving a malaria-endemic area is a medical emergency and should be investigated urgently. CauseHuman malaria is caused by four different species of
the protozoan parasite Plasmodium: Plasmodium falciparum, P. vivax, P. ovale
and P. malariae.
TransmissionThe malaria parasite is transmitted by
various species of Anopheles mosquitoes, which bite mainly between sunset and
sunrise.
Malaria is an acute febrile illness with an incubation
period of 7 days or longer. Thus, a febrile illness developing less than one
week after the first possible exposure is not malaria.
The most severe form is caused by P. falciparum, in which variable
clinical features include fever, chills, headache, muscular aching and
weakness, vomiting, cough, diarrhoea and abdominal pain; other symptoms related
to organ failure may supervene, such as: acute renal failure, generalized
convulsions, circulatory collapse, followed by coma and death. It is estimated
that about 1% of patients with P. falciparum infection die of the
disease. The initial symptoms, which may be mild, may not be easy to recognize
as being due to malaria. It is important that the possibility of falciparum
malaria is considered in all cases of unexplained fever starting at any time
between the seventh day of first possible exposure to malaria and three months
(or, rarely, later) after the last possible exposure, and any individual who
experiences a fever in this interval should immediately seek diagnosis and
effective treatment.
Early diagnosis and appropriate treatment can be life-saving. Falciparum malaria may be fatal if treatment is delayed beyond 24 hours. A blood sample should be examined for malaria parasites. If no parasites are found in the first blood film but symptoms persist, a series of blood samples should be taken and examined at 6–12-hour intervals. Pregnant women, young children and elderly travellers are particularly at risk. Malaria in pregnant travellers increases the risk of maternal death, miscarriage, stillbirth and neonatal death. The forms of malaria caused by other Plasmodium species are less severe and rarely life-threatening. Prevention and treatment of falciparum malaria are becoming more difficult because P. falciparum is increasingly resistant to various antimalarial drugs. Of the other malaria species, drug resistance has to date been reported for P. vivax, mainly from Indonesia (Irian Jaya) and Papua New Guinea, with more sporadic cases reported from Guyana. P. vivax with declining sensitivity has been reported for Brazil, Colombia, Guatemala, India, Myanmar, the Republic of Korea, and Thailand. P. malariae resistant to chloroquine has been reported from Indonesia. The current distribution of malaria in the world is
shown in the map here.
Affected countries and territories are listed on here. The risk for travellers
of contracting malaria is highly variable from country to country and even
between areas in a country.
In many endemic countries of Latin America and the Caribbean, Asia and the Mediterranean region, the main urban areas—but not necessarily the outskirts of towns—are free of malaria transmission. However, malaria can occur in main urban areas in Africa and India. There is usually less risk of the disease at altitudes above 1500 metres, but in favourable climatic conditions it can occur at altitudes up to almost 3000 metres. The risk of infection may also vary according to the season, being highest at the end of the rainy season. There is no risk of malaria in many tourist destinations in South-East Asia, Latin America and the Caribbean. Risk for travellersDuring the transmission season in malaria-endemic
areas, all non-immune travellers exposed to mosquito
bites, especially between dusk and dawn, are at risk of malaria.
This includes previously semi-immune travellers who have lost their immunity
during stays of 2 years or more in non-endemic areas. Most cases of malaria in
travellers occur because of poor compliance with prophylactic drug regimens or
use of inappropriate prophylaxis.
Travellers to countries where the degree of malaria transmission varies in different areas should seek for advice on the risk of malaria in the specific zones that they will be visiting. If specific information is not available before travelling, it is recommended to assume that there is a uniformly high malaria risk throughout the country. This applies particularly to individuals backpacking to remote places and visiting areas where diagnostic facilities and medical care are not readily available. Travellers staying overnight in rural areas may be at highest risk. Protection against mosquito bitesAll travellers should be told that
individual protection from mosquito bites between dusk and dawn is their first
line of defence against malaria.
It has to be prescribed by a doctor.
The correct dosage of the most appropriate
antimalarial drug(s) (if any) for the destination(s) should be prescribed.
Travellers and their doctors should be aware that NO
ANTIMALARIAL PROPHYLACTIC REGIMEN GIVES COMPLETE PROTECTION. The following should also be taken into
account:
Depending on the area visited the recommended
prophylaxis may be chloroquine, chloroquine plus proguanil, mefloquine or
doxycycline. In areas where mefloquine is the prophylactic drug of choice,
doxycycline or atovaquone/proguanil can be used as an alternative that can be
started the day before travel; chloroquine plus proguanil would offer less
protection. Chloroquine on its own can be recommended only for areas where
malaria is due exclusively to P. vivax or chloroquine-sensitive P.
falciparum.
All antimalarial drugs have specific contraindications
and possible side-effects. Adverse reactions attributed to malaria
chemoprophylaxis are common, but most are minor and do not affect the
activities of the traveller. Serious adverse events—defined as constituting an
apparent threat to life, requiring or prolonging hospitalization, or resulting
in severe disability—are rare. With mefloquine the incidence range of serious
adverse events has been estimated at 1 per 6000 to 1 per 10 600 travellers,
compared with 1 per 13 600 with chloroquine. The risk of drug-associated
adverse events should be weighed against the risk of malaria, especially
falciparum malaria, and local drug-resistance patterns.
Each of the antimalarial drugs is contraindicated in
certain groups and individuals, and the contraindications should be carefully
considered to reduce the risk of serious adverse reactions.
People with chronic illnesses should seek individual medical advice. Any
traveller who develops serious side-effects to an antimalarial should stop
taking the drug and seek immediate medical attention. This applies particularly
to neurological or psychological disturbances after mefloquine treatment. Mild
nausea, occasional vomiting or loose stools should not prompt discontinuation
of prophylaxis, but medical advice should be sought if symptoms persist.
Because of the risk of adverse side-effects, chemoprophylaxis should not be prescribed in the absence of malaria risk. It is important to note that malaria is not present in all tropical countries (see map and country list). Long-term use of chemoprophylaxis
The risk of serious side-effects associated with
long-term prophylactic use of chloroquine and proguanil is low. However, anyone
who has taken 300 mg of chloroquine weekly for over five years and requires
further prophylaxis should be screened twice-yearly for early retinal changes.
If daily doses of 100 mg chloroquine have been taken, screening should start
after three years. An alternative drug should be prescribed if changes are
seen. Data indicate no increased risk of serious side-effects with long-term
use of mefloquine if the drug is tolerated in the short-term. Experience with
doxycycline for long-term chemoprophylaxis (i.e. more than 4–6 months) is
limited, but available data are reassuring. Mefloquine and doxycycline should
be reserved for those at greatest risk of chloroquine-resistant infections.
Atovaquone/proguanil cannot yet be recommended for long-term chemoprophylactic
use because of the lack of data.
Stand-by emergency treatmentAn individual who experiences a fever 1 week
or more after entering an area of malaria risk should consult a physician or
qualified malaria laboratory immediately to obtain diagnosis and treatment.
Most travellers will be able to obtain medical attention within 24 hours
of the onset of fever. For a minority, however, this may be impossible,
particularly if they will be staying (1 week or more after entering an endemic
area) in a remote location. In such cases,
travellers are advised to carry antimalarial drugs for self-administration
(“stand-by emergency treatment”).
The circumstances of stand-by emergency treatment
(SBET) are different from treatment administered by competent medical
personnel. SBET is taken by a traveller who 1) is sick in a remote location and
cannot easily reach a hospital or qualified health professional, 2) may already
be taking antimalarials for prophylaxis, and 3) may have to self-diagnose
malaria based on non specific clinical symptoms such as fever. In these
circumstances the safety and efficacy of drugs given for SBET are even more
critical, and not all antimalarials that are normally used for treatment can be
confidently prescribed.
Stand-by emergency treatment may also be indicated for
travellers in some occupational groups, such as aircraft crews, who make
frequent short stops in endemic areas over a prolonged period of time. Such
travellers may eventually choose to reserve chemoprophylaxis for high-risk
areas only. However, they should continue to take rigorous measures for
protection against mosquito bites and be prepared for an attack of malaria: they
should always carry a course of antimalarial drugs for stand-by emergency
treatment, seek immediate medical care in case of fever, and take stand-by
emergency treatment if prompt medical help is not available.
Stand-by emergency treatment—combined with rigorous
protection against mosquito bites—may occasionally be indicated for those who
travel for 1 week or more to remote rural areas where there is a very low
likelihood of multidrug-resistant malaria and the risk of side-effects of
prophylaxis outweighs the risk of contracting malaria. This may be the case in
certain border areas of countries in South-East Asia where
the risk of side-effects may outweigh the risk of becoming infected. However,
most travellers to these areas will be able to access competent medical care
within 24 hours of the onset of fever.
Travellers provided with stand-by emergency treatment should be given clear and precise written instructions on the recognition of symptoms, when and how to take the treatment, the treatment regimen, possible side-effects, and the possibility of drug failure. They should be made aware that self-treatment is a first-aid measure, and that they should seek medical advice as soon as possible. In general, travellers carrying stand-by emergency
treatment should observe the following guidelines:
Artemether/lumefantrine has been registered in Switzerland for use
as stand-by emergency treatment for travellers to areas where the parasite is
resistant to other drugs. In addition, some national health authorities
recommend atovaquone/proguanil as SBET for areas of multidrug resistance. See
Table 7.3 for details on individual drugs.
Halofantrine is contraindicated for stand-by treatment following reports that it can result in ventricular dysrhythmias, prolongation of Q–T intervals and sudden death in susceptible individuals. These risks may be accentuated if halofantrine is taken with other antimalarial drugs that may reduce myocardial conduction. P. vivax and P. ovale can remain quiescent in the
liver for many months. Relapses caused by the persistent liver forms may appear
months, and rarely up to 2 years, after exposure. They are not prevented by
current chemoprophylactic regimens. Relapses can be treated with chloroquine
(or mefloquine or quinine if resistance is suspected) and further relapses
prevented by a course of primaquine, which eliminates any remaining parasites
in the liver. In patients with known or suspected glucose-6-phosphate
dehydrogenase (G6PD) deficiency, expert medical advice should be sought since
primaquine may cause haemolysis in G6PD-deficient patients. G6PD deficiency
must be excluded before travellers receive antirelapse therapy with primaquine.
Blood infection with P. malariae may be present for many years, but it
is not life-threatening. It can be treated with chloroquine (or mefloquine or
quinine if resistance is suspected)
Some groups of travellers, especially young children
and pregnant women, are at particular risk of serious consequences if they
become infected with malaria.
Malaria in a pregnant woman increases the risk of
maternal death, miscarriage, stillbirth and low birth weight with associated
risk of neonatal death.
Pregnant women should be advised to avoid travelling to areas where chloroquine-resistant P. falciparum occurs. When travel cannot be avoided, it is very important to take effective preventive measures against malaria, even when travelling to areas with transmission of vivax malaria only. Pregnant women should be extra diligent in using measures to protect against mosquito bites, but should take care not to exceed the recommended dosage of insect repellents. In the few areas with exclusively P. vivax transmission
or where P. falciparum can be expected to be 100% sensitive to
chloroquine, prophylaxis with chloroquine alone may be used. In areas with
chloroquine-resistant P. falciparum, prophylaxis with chloroquine plus
proguanil can be safely prescribed during the first 3 months of pregnancy.
However, its efficacy may be severely limited. Mefloquine prophylaxis may be
given during the second and the third trimesters, but should be used with
caution during the first trimester. Other drugs are either dangerous to the
fetus or have been insufficiently well investigated to be prescribed for
prophylaxis in pregnancy.
Pregnant women should seek medical help immediately if malaria is suspected; if this is not possible, they should take emergency stand-by treatment with quinine. Medical help must be sought as soon as possible after stand-by treatment. Pregnant women with falciparum malaria may rapidly
develop any of the clinical symptoms of severe malaria. They are particularly
susceptible to hypoglycaemia and pulmonary oedema. They may develop postpartum
haemorrhage, and hyperpyrexia leading to fetal distress. Any pregnant woman
with severe falciparum malaria should be transferred to intensive care. Because
of the risk of quinine-induced hyperinsulinaemia and hypoglycaemia, artesunate
and artemether are the drugs of choice for treatment of severe malaria in the
second and third trimester. Data on the use of artemisinin derivatives in the
first trimester are still limited.
Information on the safety of drugs during
breastfeeding is provided in Tables 7.2 and 7.3.
Both mefloquine and doxycycline prophylaxis may be
taken, but pregnancy should preferably be avoided during the period of drug
intake and for 3 months after mefloquine and 1 week after doxycycline
prophylaxis is stopped.
If pregnancy occurs during antimalarial prophylaxis with mefloquine of doxycline, this is not considered to be an indication for pregnancy termination. Young children
Falciparum malaria in a young child is a medical
emergency—it may be rapidly fatal. Early symptoms are atypical and difficult to
recognize, and life-threatening complications can occur within hours of the
initial symptoms.
Parents should be advised not to take babies or young children to areas with transmission of chloroquine-resistant P. falciparum. If travel cannot be avoided, children must be very carefully protected against mosquito bites and be given appropriate chemoprophylactic drugs. Babies should be kept under insecticide-treated mosquito nets as much as possible between dusk and dawn. The manufacturer's instructions on the use of insect repellents should be followed diligently, and the recommended dosage must not be exceeded. Breastfed, as well as bottle-fed, babies, should be given chemoprophylaxis since they are not protected by the mother's prophylaxis. Dosage schedules for children should be based on body weight. Chloroquine and proguanil are safe for babies and young children, and mefloquine may be given to infants of more than 5 kg body weight. Atovaquone/proguanil cannot be recommended for prophylaxis in children who weigh less than 11 kg because of the lack of data. Doxycycline is contraindicated in children below 8 years of age. All antimalarial drugs should be kept out of the reach of children and stored in childproof containers. Chloroquine is particularly toxic to children in case of overdose. Medical help should be sought immediately if a child develops a febrile illness: malaria should always be suspected and laboratory diagnosis is essential. In infants, malaria should be suspected even in non-febrile illness. The possibility of malaria should be considered whenever a child develops a fever within a year of travelling to or immigrating from an endemic area. Laboratory diagnosis should be requested immediately if malaria is suspected, and treatment with an effective antimalarial drug initiated as soon as possible. In border areas between Cambodia, Myanmar and Thailand, P.
falciparum infections do not respond to treatment with chloroquine or
sulfadoxine–pyrimethamine, and sensitivity to quinine is reduced. Treatment
failures in excess of 50% with mefloquine are also being reported. In these
situations, doxycycline or atovaquone/proguanil can be used for
chemoprophylaxis together with rigorous personal protection measures. However,
these drugs cannot be given to pregnant women and children. Since there is no
prophylactic regimen that is both effective and safe for these groups in areas
of multidrug-resistant malaria, pregnant women and young children should avoid
travelling to these malarious areas.
In the Amazon basin of South
America, mefloquine resistance has been reported only
from Brazil, where
clinical failure rates remain below 5%.
Travellers may protect themselves from mosquitoes and
other vectors by the means outlined in the following paragraphs.
Insect repellents are substances applied to exposed skin or to clothing to prevent human/vector contact. The active ingredient in a repellent repels but does not kill insects. Choose a repellent containing DEET (N,N-diethyl-m-toluamide), IR3535® (3-[N-acetyl-N-butyl]-aminopropionic acid ethyl ester) or Bayrepel® (1-piperidinecarboxylic acid, 2-(2-hydroxyethyl)-, 1-methylpropylester). Insect repellents should be applied to provide protection at times when insects are biting. Care must be taken to avoid contact with mucous membranes. Insect repellents should not be sprayed on the face or applied to the eyelids or lips. Always wash the hands after applying the repellent. Insect repellents should not be applied to sensitive, sunburned or damaged skin or deep skin folds. Repeated applications may be required every 3–4 hours, especially in hot and humid climates. When the product is applied to clothes, the repellent effect lasts longer. Repellents should be used in strict accordance with the manufacturers’ instructions and the dosage must not be exceeded, especially for young children. Mosquito coils are the best known example of insecticide vaporizer, usually with a synthetic pyrethroid as the active ingredient. One coil serves a normal bedroom through the night, unless the room is particularly draughty. A more sophisticated version, which requires electricity, is an insecticide mat that is placed on an electrically heated grid, causing the insecticide to vaporize. Aerosol sprays intended to kill flying insects are effective for quick knockdown and killing. Indoor sleeping areas should be sprayed before bedtime. Treating a room with an insecticide spray will help to free it from insects, but the effect may be short-lived. Spraying combined with the use of a coil, a vaporizer or a mosquito net is recommended. Aerosol sprays intended for crawling insects (e.g. cockroaches and ants) should be sprayed on surfaces where these insects walk. Protective clothing can be help at times of the day when vectors are active. The thickness of the material is critical, and no skin should be left exposed unless treated with a repellent. Insect repellent applied to clothing is effective for longer than it may be on the skin. Extra protection is provided by treating clothing with permethrin or etofenprox, to prevent mosquitoes from biting through clothing. Label instructions should be followed to avoid damage to certain fabrics. In tick- and flea-infested areas, feet should be protected by appropriate footwear and by tucking long trousers into the socks. Such measures are further enhanced by application of repellents to the clothing. Mosquito nets are excellent means of
personal protection while sleeping. Nets can be used either with or without
insecticide treatment. However, treated nets are much more
effective. Pretreated nets may be commercially available. Nets should be strong
and with a mesh size no larger than 1.5 mm. The net should be tucked in under
the mattress, ensuring first that it is not torn and that there are no
mosquitoes inside. Nets for use with cots and small beds are available,
affording protection for babies whenever they are sleeping.
Travellers camping in tents should use a combination
of mosquito coils, repellents and screens. The mesh size of tent screens often
exceeds 1.5 mm, so that special mosquito screens have to be deployed.
Screening of windows, doors and eaves reduces exposure
to flying insects. Accommodation with these features should be sought where
available.
Air-conditioning is a highly effective means of
keeping mosquitoes and other insects out of a room. In air-conditioned hotels,
other precautions are not necessary indoors.
Avoid contact with freshwater bodies such as lakes,
irrigation, ditches and slow-running streams in areas where schistosomiasis
occurs.
Principal disease vectors and the disease they transmit*
* Based on extensive research, there is absolutely no evidence that HIV infection can be transmitted by insects.Air-conditioning
is a highly effective means of keeping mosquitoes and other insects out of a
room. In air-conditioned hotels, other precautions are not necessary indoors.
Contact with fresh water (lakes, slow-running streams) is to be avoided in areas where schistosomiasis is prevalent. For occupational contact (for example, irrigation consultants visiting an affected area), protective boots are recom-mended. Countries and territories with malarious areaThe following list shows all countries where malaria
occurs. In some of these countries, malaria is present only in certain areas or
up to a particular altitude. In many countries, malaria has a seasonal pattern.
(* = P. vivax risk only)
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