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Malaria

Introduction

Most important parasitic disease in tropical and subtropical countries. It is currently endemic in over 100 countries and It is a serious and sometimes fatal disease.

Tropical Africa is a much higher-risk destination compared to Latin America and Asia for following reasons:-

  1. Tourists in Africa spend considerable time in rural areas e.g. game parks. However, tourists in Latin America and Asia spend more time in urban or resort areas.
  2. Malaria is transmitted even in most large cities in sub-Saharan Africa. In Latin America and Asia, transmission is more seasonal or focally distributed in rural areas.
  3. The infection rate of Mosquitoes with malaria parasites in Africa is higher and more apt to be carrying Malaria parasites.

Causative agent:

Human Malaria is caused by four different species of the protozoan parasite Plasmodium: Plasmodium falciparum, P.vivax, P.ovale and P.malariae.

Transmission:

Transmitted by various species of Anopheles mosquitoes, which bite mainly between sunset and sunrise

Incubation period: 7 days or longer

Pregnant women, young children and elderly travelers are particularly at risk.

Chloroquine-resistant P. falciparum malaria is widespread. Exceptions are north / west of Panama Canal, Egypt and most of Middle East. Mefloquine-resistant P. falciparum malaria is found in border areas of Thailand, Vietnam and Laos. Multi-drug resistant P. falciparum malaria is reported from Vietnam and Amazon basin of South America.

Sign & Symptoms

Any individual who experiences a fever at any time between the seventh day of first possible exposure to malaria and three months (or rarely later), should immediately seek diagnosis and effective treatment.

(Fever developing less than one week after the first possible exposure is NOT Malaria).

Most severe form is caused by P. falciparum with variable clinical features include fever, chills, headache, muscular aching and weakness, vomiting, cough, diarrhea and abdominal pain.

The forms of Malaria caused by other Plasmodium species are less severe and rarely life-threatening.

Complication

Acute organ failure, generalized convulsions, circulatory collapse followed by coma and death.

Treatment

Early diagnosis and appropriate treatment can be life saving. Many travelers will be able to obtain proper medical attention within 24hrs of the onset of fever.

Stand-By Emergency Treatment (SBET) is taken by a traveler who

  • is sick in a remote location and cannot easily reach a hospital or qualified health professional
  • may already be taking antimalarials for prophylaxis
  • may have to self-diagnose malaria based on non specific clinical symptoms such as fever.

Travelers carrying SBET should observe the following guidelines;

  • Consult a physician immediately if fever occurs 1 week or more after entering an area with Malaria risk
  • If it is impossible to consult a physician and/or establish a diagnosis within 24hours of the onset of fever, start the emergency treatment and seek medical care as soon as possible for complete evaluation and to exclude other serious causes of fever
  • Complete the SBET course and resume antimalarial prophylaxis 1 week after the first treatment dose.
  • Do Not treat suspected Malaria with the same drugs used for prophylaxis, because of the increased risk of toxicity and resistance.

Note: A drug selected for SBET should always be different from the drugs used for prophylaxis, and should be one to which no resistance has been reported in the countries to be visited.

Choice of SBET according to recommended chemoprophylactic regimen

Recommended prophylactic Regimen SBET
None Chloroquine (for P.Vivax areas Only),Mefloquine, Quinine Artemether and lumefantrine* Atovaquone/proguanil*
Chloroquine alone OR Proguanil Mefloquine, Quinine
Mefloquine Quinine**, Quinine + Doxycycline Or tetracycline for 7 days**
Doxycycline Mefloquine Quinine + Tetracycline for 7 days
Atovaquone/ proguanil Quinine + Doxycycline/ Tetracycline For 7 days

* Limited experience at present on drug interactions of artemether/lumefantrine and atovaquone/proguanil with other antimalarial drugs. Therefore, if the patient is already taking an antimalarial as prophylaxis, these drugs should only be used if no other antimalarial treatment option is available.

** Mefloquine prophylaxis should only be resumed 7 days after the last self-treatment dose of quinine.

Prevention & Precautions

Four principles of protection

  1. Be Aware of risk, incubation period, main symptoms and possible late onset of Malaria due to P. vivax and P. ovale.
  2. Avoid being Bitten by mosquitoes, especially between dusk and dawn and use personal protective measures
  3. Take Chemoprophylaxis. Be aware that no regimen gives complete protection although it does reduce risk of fatality. Relapse Malaria is not prevented by current chemoprophylactic regimens.
  4. Immediately seek Diagnosis and treatment if a fever develops one week or more after entering and up to four years after departure from a risk area.

Minimize exposure to bites by modifying activities to avoid exposure to vector bites. Anopheles mosquitoes feed between dusk and dawn Avoid outdoor activity during these periods.

Avoid mosquito bite by applying mosquito repellent to exposed skin. When using sunscreen or lotions, apply repellants last. Reapply whenever sweat or water has removed it. Active ingredient in a repellent repels but does not kill insects. Repellent that contains DEET (N, N-diethylmetatoluamide) is most reliable and long-lasting type (35% DEET provides protection for 12 hours). DEET formulations as high as 50% are recommended for both adults (including pregnant women) and children >2 months of age. It is toxic when ingested and may cause skin irritation. Permethrin is highly effective both as an insecticide and as a repellent. There is little potential for toxicity from Permethrin-treated clothing.

Use long sleeved clothes and long pant. Avoid wearing dark colours (attract mosquitoes).

Close windows or shutters at night when indoors. Use pyrethrum insecticide spray (aerosol insecticides), pyrethroid coils or insecticide impregnated tablets in evening before sleep.

Avoid strong perfumes, hair sprays or after-shaves (attract mosquitoes)!

Use air-conditioning or good mosquito net especially treated with Permethrin.

There is No immunisation against Malaria presently.

Pregnant women and young children require special attention because of potential effects of Malaria illness on the fetus and the inability of pregnant women and young children to tolerate certain drugs.

The possible malaria prophylaxis regimens are: check with VBDCP Chloroquine phosphate (Aralen) – not effective against Plasmodium falciparum Malaria in most countries. Weekly Chloroquine should be started 1 week before arrival.

Mefloquine (Lariam) – used for areas where drug-resistant P. falciparum exists. Not for pregnant women, children less than 13.6 kg in weight or people taking heart or epileptic medications. Weekly Mefloquine should be started at least one week but preferably 2 – 3 weeks before departure.

Pyrimethamine / Sulfadoxime (Fansidar) – not for use by people who are allergic or sensitive to sulfphur drugs and infants less than 2 months of age. Self-treatment with Fansidar is not a substitute for prompt medical care, but is rather an attempt to prevent life-threatening Malaria infection.

Doxycycline (Vibratab) – may cause photosentivity. Not for use by people who are allergic to tetracycline drugs, pregnant women or children less than 8 years of age.

Proguanil/atovaquone (Malarone) – in combination with weekly Chloroquine phosphate, is used when travelling in East Africa and when use of Mefloquine is not possible. Should not be used for prophylaxis in children weighing 11kg because of lack of data on safety and efficacy.

All prophylactic drugs should be continued for 4 weeks after last possible exposure. Exception is Proguanil which can be stopped one week after return.

Drugs used in the prophylaxis of Malaria

Drug Usage Adult Dose Pediatric Dose Comments
Atovaquone / proguanil (Malarone) Prophylaxis in areas with chloroquine-resistant or mefloquine-resistant P. falciparum.

Adult tablets contain 250 mg atovaquone and 100 mg proguanil hydrochloride.

1 adult tablet orally, daily

Pediatric tablets contain 62.5 mg atovaquone and 25 mg proguanil hydrochloride.

11-20 kg: 1 tablet

21-30 kg: 2 tablets

31-40 kg: 3 tablets

41 kg or more: 1 adult tablet daily

Begin 1-2 days before travel to malarious areas. Take daily at the same time each day while in the malarious area and for 7 days after leaving such areas. Contraindicated in persons with severe renal impairment (creatinine clearance atovaquone proguanil should be taken with food or a milky drink. not recommended for prophylaxis children 11 pregnant and women breastfeeding infants weighing kg.
Chloroquine phosphate (Aralen and generic) Prophylaxis only in areas with chloroquine-sensitive P. falciparum. 300 mg base (500 mg salt) orally, once/week 5 mg/kg base (8.3 mg/kg salt) orally, once/week, up to maximum adult dose of 300 mg base.

Begin 1-2 weeks before travel to malarious areas. Take weekly on the same day of the week while in the malarious area and for 4 weeks after leaving such areas.

May exacerbate psoriasis.

Doxycycline (Many brand names and generic) Prophylaxis in areas with chloroquine-resistant or mefloquine-resistant P. falciparum. 100 mg orally, daily 8 years of age: 2 mg/kg up to adult dose of 100 mg/day.

Begin 1-2 days before travel to malarious areas. Take daily at the same time each day while in the malarious area and for 4 weeks after leaving such areas.

Contraindicated in children8 years of age and pregnant women.

Hydroxychloro- quine sulfate (Plaguenil) An alternative to chloroquine for prophylaxis only in areas with chloroquine-sensitive P. falciparum. 310 mg base (400 mg salt) orally, once/week 5 mg/kg base (6.5 mg/kg salt) orally, once/week, up to maximum adult dose of 310 mg base. Begin 1-2 weeks before travel to malarious areas. Take weekly on the same day of the week while in the malarious area and for 4 weeks after leaving such areas.
Mefloquine (Lariam and generic) Prophylaxis in areas with chloroquine-resistant P. falciparum. 228 mg base (250 mg salt) orally, once/week

9 kg: 4.6 kg base 5 week atovaquone proguanil should be taken with food or a milky drink. not recommended for prophylaxis children 11 pregnant and women breastfeeding infants weighing kg. <8 years=”” of=”” age=”” and=”” pregnant=”” p=””>

10-19 kg: 1/4 tablet once/week

20-30 kg: 1/2 tablet once/week

31-45 kg: 3/4 tablet once/week

46 kg: 1 tablet once/week

 

Begin 1-2 weeks before travel to malarious areas. Take weekly on the same day of the week while in the malarious area and for 4 weeks after leaving such areas. Contraindicated in persons allergic to mefloquine or related compounds (e.g., quinine and quinidine) and in persons with active depression, a recent history of depression, generalized anxiety disorder, psychosis, schizophrenia, other major psychiatric disorders, or seizures. Use with caution in persons with psychiatric disturbances, or a previous history of depression. Not recommended for persons with cardiac conduction abnormalities.
Primaquine An option for prophylaxis in special circumstances. Call Malaria Hotline (770-488-7788) for additional information. 30 mg base (52.6 mg salt) orally, daily 0.6 mg/kg base (1.0 mg/kg salt) up to adult dose orally, daily

Begin 1-2 days before travel to malarious areas. Take daily at the same time each day while in the malarious area and for 7 days after leaving such areas.

Contraindicated in persons with G6PD1 deficiency. Also contraindicated during pregnancy and lactation unless the infant being breastfed has a documented normal G6PD level. Use in consultation with malaria experts.

Primaquine Used for presumptive anti-relapse therapy (terminal prophylaxis) to decrease the risk of relapses of P. vivax and P. ovale. 30 mg base (52.6 mg salt) orally, once/day for 14 days after departure from the malarious area. 0.6 mg/kg base (1.0 mg/kg salt) up to adult dose orally, once/day for 14 days after departure from the malarious area. Indicated for persons who have had prolonged exposure to P. vivax and P. ovale or both. Contraindicated in persons with G6PD1 deficiency. Also contraindicated during pregnancy and lactation unless the infant being breastfed has a documented normal G6PD level.

Glucose-6-phosphate dehydrogenase. All persons who take primaquine should have a documented normal G6PD level prior to starting the medication.

References organisation/ support

International Travel & Health, WHO 2006

Control of Communicable Diseases Manual, 18th Edition by David L. Heymann, MD, Editor, 2004

http://travelhealth.co.uk/

Last Reviewed : 26 April 2012
Writer : Dr. Norhayati Rusli
Reviewer : Dr. Muhaini Othman