MALARIA

With thanks to  Dr. Marc Shaw of the Traveller's Health Centre 72 Remuera Road, New Market, Auckland 09-520-5830 & Dr. Geoff Kivell (The Floating Doc)  S/V "Aspect of Arran"

Malaria is the world's most prevalent tropical disease. It affects 400 million people a year and kills approximately 2 million, mainly children. Malaria is caused by a parasitic protozoa that is transmitted from person to person by the bite of a mosquito found in tropical areas.

Disclaimer: 

Whilst every effort is made to provide current and accurate information and advice,  no liability is accepted by the Island Cruising Association for any incorrect statement or advice.

Quick Links to sections on this page:

• What is Malaria?
• Contracting
• Incubation period
• Diagnosis
• Treatment
• Self treatment doses
• Paediatric Standby Treatment Doses
• Prevention
• Prophylactic Prevention Doses
• Paediatric Prophylactic Prevention Doses

What is malaria?

Malaria is an illness caused by a parasite that is transmitted by the bite of a female anopheline mosquito. The CLASSICAL symptoms are shivers, called rigors or chills, that alternate with high fevers. As the fever drops there is usually extreme sweating. Occasionally diarrhoea can be a prominent symptom. Malaria doesn't always present with classical symptoms, however, so anyone who gets a fever in a malarious area should be presumed to have the disease and tested accordingly.

In between episodes of fever the patient can appear deceptively well. As malaria does not always cause the classic pattern of symptoms, the golden rule is that any fever could be malaria in any person who has been in a malarious area any time in the past 12 months.

There are 4 species of parasite that cause malaria. One is potentially rapidly fatal (malignant malaria), often resulting in 'cerebral' malaria. This is caused by Plasmodium falciparum. Malignant malaria may progress to life threatening coma or a severe state of shock.

The other form, benign malaria, may produce recurrent episodes of fever, sometimes over many years. Benign malaria is caused by one of three other species. Plasmodium vivax, Fliasmodium ovale or Plasmodium malariae. These cause similar symptoms to falciparum malaria, but do not cause brain or'cerebral' malaria. or shock. Death due to benign forms of malaria is very rare but can occur, usually from trauma to the spleen that causes a rapidly fatal loss of blood into the abdomen.

How do you contract malaria?

Malaria is transmitted from the bite of a particular species of mosquito (an anopheline mosquito); these mosquitoes bite between dusk and dawn; 2 hours after dusk and 2 hours before dawn are the most common times. Risk levels for various areas around the world are constantly changing, as are the recommended antimalaria medications for prevention and treatment. Malaria risk areas and recommended antimalaria medications for specific travel itineraries are outlined in the Country Reports database. Rarer ways of catching malaria include blood transfusion and sharing contaminated needles, e.g. intravenous drug abuse.

What is the incubation period (time from exposure to first symptoms)?

The incubation period for malaria symptoms is about 10 to12 days for malignant malaria (minimum is 7 days) but commonly around 30 days for the benign form. Sometimes the malignant form may not occur until 12 months after the fast exposure to infected mosquitoes. The benign form may not appear until 5 years or more after leaving a malarious area.

How is malaria diagnosed?

Malaria is best diagnosed at the time of sweating or fever by microscopic examination of a blood film. Three to four blood tests collected over a 72 hour period should be taken. Even if negative, the person could still have malaria and may require further testing to find the organisms in the blood. If there is any doubt it is often best to treat for malaria, as untreated malignant malaria can be rapidly fatal.

What is the treatment for malaria?

Specific anti-malarial medications will effectively treat malaria. If the treatment is given too late, however, death can occur. Treatment is with drugs, although resistance is increasing. There are five medications generally available in New Zealand: Atovaquone and Proguanif (a combination called Malarone), Chforoquine, Doxycycline, Mefloquine and Proguanil. Each is effective under certain circumstances and in certain regions of the world.

1. ATOVAQUONE and PROGUANIL (combination). This combination medication is the newest one available in New Zealand. It is extremely effective and has very few side effects (reported: headaches, stomach upsets and abdominal pain).

2. CHLOROQUINE Until recently chloroquine has been the most commonly used medicine for malaria. It rarely causes serious side effects but may cause stomach upsets, headaches, dizziness, blurred vision. These side effects are reduced if chloroquine is taken after a meal. The common belief that chloroquine causes eye disease is exaggerated. Only individuals who take large doses over 2 to 5 years risk eye damage.

3. DOXYCYCLINE is an antibiotic with anti-malarial properties. Women receiving doxycycline may develop vaginal itch and thrush. All those on the medication may get stomach upsets or abnormal skin sensitivity to sunlight. The medication does provide some protection against travellers' diarrhoea. The overall risk of complications is about 8%.

4. MEFLOQUINE can cause dizziness, headaches, strange dreams, sleep disturbance, mood changes, anxiety and palpitations. Risk is about 5%, but is heightened if alcohol is taken within 24 hours of taking the weekly dose. Mefloquine can cause severe neuropsychiatric side effects; these have been much reported in the non medical press and by personal experience.

5. PROGUANIL is a safe anti-malarial. Occasionally it causes rashes, dizziness, heartburn, nausea, diarrhoea and mouth ulcers: but these are all minimised by taking the medication after food. It is safe to use in pregnancy and safe for use in children.

The malarial parasite is becoming increasingly resistant to anti-malarial drugs so there is no one drug that is completely safe and effective against malaria. The choice of medicines depends on a number of factors such as the traveller's age and current health status, the intensity of mosquito contact and level of malaria in the area or country.

Self Treatment Doses of Medications for Malaria Available in New Zealand:

A - Atovaquone and Proquanil (MALARONE)

Medication	Adult	Child	General comment
Atovaquone (250 mg) and Proguanil (100 mg) MALARONE	4 tablets a day for three days	See below	Malarone has been shown to be highly efficacious for treatment of uncomplicated malaria caused by Plasmodium falciparum, including malaria that has been acquired in areas with chloroquine-resistant or multi-drug resistant strains.

B - Mefloquine (Larium)

Medication	Adult	Child	General comment
Mefloquine Larium (250 mg)	If weight is >60kg 3 tabs start 2 tabs @6-8 hours 1 tab 6-8 hours after If weight is 45-60kg 3 tabs start 2 tabs @ 6-8 hours	See below	Beter tolarated in children. Severe side effects in 1:10,000. Side effects are over-stated. General side effects in the order of 1:200

C - Quinine and Tetracycline

Medication	Adult	Child	General comment
Quinine (300mg) accompanied by: Tetracyine (250 mg)	2 tabs three times a day 1 tab four times a day	This combination is not generally indicated in childhood	Qunine: duration 3 days Tetracycline: duration 7 days.

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Paediatric Standby Treatment Doses:
A - ATOVAQUONE and PREGUANIL Recommended treatment dosages for CHILDREN

Weight (kg)	11-20 kg body weight	21-30 kg bodyweight	31-40 kg bodyweight	>40 kg bodyweight
Number of tablets per day.	One tablet daily for three consecutive days.	Two tablets as a single dose for three consecutive days.	Three tablets as a single dose for 3 consecutive days.	Four tablets as a single dose for 3 consecutive days.

B - MEFLOQUINE recommended STANDBY TREATMENT dosages for CHILDREN (WHO recommendations)

Medication	Single Dose	Split dose	General comment
Mefloquine Larium (250mg)	15mg mefloquine base per kg body weight	15mg mefloquine base per kg body weight followed by 10mg base per kg body weight 6-24 hours later.	Mefloquine is contraindicted during the first 3 months os pregnancy and in infants weighing less than 5kg.

How do you prevent malaria?

Prevention of mosquito bites remains the BEST way to avoid malaria. It is recommended that you:

• Avoid mosquito bites between dusk and dawn.

• Take anti-malaria preventative medicine. This reduces the risk of getting the disease but none of the medications is 100% effective in preventing malaria.

• Note that medication should always be used in combination with anti-mosquito measures such as mosquito nets and insect repellent. Consider other preventative measures, such as:

  • dressing appropriately in long sleeves and long trousers
  • using personal insect repellents with DEET
  • sleep in air conditioned accommodation or under permethrin impregnated mosquito nets

Prophylactic Prevention Doses of Medications for Malaria, Available in New Zealand.

There are five common medications for malaria prevention available in New Zealand and Australia. None of the medicines is 100% effective against the disease at all times, and each has its own side effects. Listed below in order of preference are our recommendations for this country.

Medication	Adult	Start/Stop	General Comment
Atovaquone (250mg) and Proquanil (100mg) MALARONE	1 tablet a day	Start two days before trip. Take during visit. Stop 1 week after visit to maralious area.	Malarone has been shown to be highly efficacious for treatment of uncomplicated malaria caused by Plasmodium falciparurn, including malaria that has been acquired in visit to malarious areas with chloroquine-resistant or multi-drug resistant strains.
CHLOROQUINE (150mg base tablets)	2 tablets a week	Start 1 week before trip. Take during visit. Stop after 4 weeks after visit to malarious area	Safe in pregnancy, factation and in children
DOXYCYCLINE 100mg tablets	1tablet daily	Start 2 days before trip. Take during visit. Stop after 4 weeks after visit to malarious area	Not in children under 8 years SE: thrush, GI, skin.
Mefloquine LARIUM (250mg)	1 tablet a week	Start 3 weeks before trip. Take during visit. Stop 4 weeks after visit to malarious area	Better tolerated in children. Severe side effects in 1:10,000 General side effects in 1:200 Side effects over-rated
PROGUANIL (100mg)	2 tablets a day	Start 1 day before trip. Take during visit. Stop 4 weeks after visit to malarious area.	Take frolic acid if pregnant. Safe in women and children.

WHO: Atovaquine/Proguanil cannot be recommended for long term chemoprophylactic use because of lack of data; European countries have restricted its use to 28 days.

Paediatric Prophylactic Prevention Doses:

MEFLOQUINE recommended PROPHLAXIS doses for CHILDREN (WHO recommendations)

Weight (kg)	Age (years)	Number of tablets per week
>5	>3 months	not recommended
5-6	3 months	0.25
7-8	4-7 months	0.25
9-12	8-23 months	0.25
13-16	2-3	0.33
17-24	4-7	0.5
25-35	8-10	0.75
36-50	11-13	1
50+	14+	1

ATOVAQUINE and PROGUANIL recommended PROPHYLAXIS doses for children. (WHO recommendations)

Weight (kg)	Number of tablets per week
11-20 kg bodyweight	1 paediatric tablet 62.5 mg AYOVAQUINE + 25 mg PROGUANIL
21-30 kg bodyweight	2 paediatric tablets 62.5 mg AYOVAQUINE + 25 mg PROGUANIL
31-40 kg bodyweight	3 paediatric tablet 62.5  mg AYOVAQUINE + 25 mg PROGUANIL
>40 kg bodyweight	1 adult tablet 250 mg AYOVAQUINE + 100 mg PROGUANIL