Understanding and Addressing Relapsing Malaria

Journeying to regions endemic with malaria exposes travelers to risks beyond initial exposure, as evidenced by the potential development of relapsing malaria even after returning home. Despite adherence to malaria prophylaxis, individuals may encounter fever months or years post-travel, prompting immediate medical attention.

Malaria medications such as chloroquine, doxycycline, or mefloquine effectively suppress acute symptoms by targeting bloodstream parasites. However, specific strains host persistent liver phases, eluding these medications and inducing relapses. Notably, the P. falciparum strain, lacking a relapsing phase, succumbs to prophylactic measures. Nevertheless, sustained medication for four weeks post-exposure ensures comprehensive parasite clearance.

Distinct strains like P. vivax, ovale, or malariae establish dormant liver infections, fostering potential relapses over prolonged periods. Consequently, post-travel blood donation restrictions of up to three years aim to prevent inadvertent transmission.

In cases of relapsing malaria, treatment involves acute symptom suppression with chloroquine followed by liver infection eradication via primaquine. However, primaquine's elevated toxicity, particularly in G6PD-deficient individuals, necessitates pre-treatment screening to mitigate adverse effects.

Prevention remains paramount in combating relapsing malaria. Utilizing insect repellents (with 20-30% DEET) and mosquito netting alongside prophylactic medications minimizes infection risks.

Post-travel vigilance is crucial. Persistent fever and flu-like symptoms warrant immediate medical evaluation, with malaria among differential diagnoses. Early detection facilitates timely intervention, averting complications.

In conclusion, although uncommon, relapsing malaria presents a significant health concern for travelers returning from endemic areas. Understanding the limitations of prophylactic medications and the persistence of certain parasite strains underscores the importance of preventive measures and prompt medical intervention. By adhering to prescribed protocols and maintaining vigilance post-travel, individuals can mitigate the risk of relapsing malaria and safeguard their well-being.
Understanding and Addressing Relapsing Malaria

Anopheles mosquitoes

Malaria is caused by a Protozoan parasites transmitted by female anopheline mosquitoes of the genus Anopheles, as they are the blood-feeders.

There are approximately 422 species of Anopheles mosquitoes throughout the world. Of these, approximately 75 are considered to be important vectors of malaria.

Malaria is primarily transmitted in tropical or subtropical regions by the bite of an infected Anopheles mosquito. As insects are night-active, in general, the bite takes place between sundown and sunrise, specifically inside houses or other kinds of living spaces.

Anopheles can be distinguish from other adult mosquitoes by the way that the female, when taking a blood feed, inclines her whole body at an angle to her victim, whole in the other, culicine mosquitoes, the body is parallel to the skin surface.
Anopheles mosquitoes

Plasmodium falciparum

Plasmodium parasites are single-celled eukaryotes with a multi-stage life cycle involving development within both human and mosquito hosts.

There are four types of human malaria –Plasmodium falciparum, Plasmodium vivax, Plasmodium malariae and Plasmodium ovale.

Plasmodium falciparum and Plasmodium vivax are the most common forms of human malaria with Plasmodium falciparum is by far the most deadly type of malaria infection causing more than a million deaths, particularly in Africa.

Its cyclic paroxysms occur every 36 to 48 hours. It ranks second in prevalence and is chiefly a tropical species. Clinically, Plasmodium falciparum infections are the most serious of the four, it tends to run a shorter course without relapse.

The incubation period for Plasmodium falciparum malaria in human blood before symptom begin to show is between 10 to 14 days, during which time the parasites undergo several reproductive cycles and their numbers grow.

Once the population of parasites has become large enough, the rupture of the blood cells and their release of parasites cause the victim to feel chills, one of the most common symptoms.

In addition to fever with rigors, nausea, and hot and cold phases, Plasmodium falciparum infection can also present with diarrhea and cough. Serious complications include severe anemia, cerebral involvement and failure of major organs such as kidneys and liver.
Plasmodium falciparum

Etiology of malaria

The main cause of malaria is infection by the protozoan Plasmodium, which is spread by mosquitoes from an infected human host.

Malaria, among the most lethal of worldwide human infection is transmitted by the bite of an infective female Anopheles mosquito, which serves as the vector and definitive host.

Four species of Plasmodium infect humans: P. falciparum, P. ovale, P. malariae and P. vivax.

Of these species P. falciparum is the most virulence of the human malaria parasites and is responsible for bulk of the malaria related morbidity and mortality.

Perhaps the most important is the fact that many mosquito bites may not result in malaria, yet one can get malaria after a few bites or even without being bitten recently, depending on the mosquito spices that is biting.

The infection can be transmitted through exposure to infected blood and blood products, organ transplantation, or contaminated needles or by vertical transmission.

The most common clinical manifestation of acute malaria infection are fever, rigors, malaise, headaches, myalgias, and arthralgias. Splenomegaly is the most consistent physical finding.
Etiology of malaria

Plasmodium and malaria

Plasmodium, commonly known as the malaria parasite, is a large genus of parasitic protozoa. There are four main forms of human malaria. In humans, the causative agents are four species of plasmodium protozoa (single celled parasites), including vivax, falciparum, malariae and ovale.

The strains of malaria such as P. vivax, ovale, or malariae can infect the liver and persist in a dormant state for months, or even up to several years, after exposure.

Plasmodium vivax is perhaps the most prevalent of the four and is the species most frequently encountered in temperate zone. Plasmodium vivax is a tertian malaria since its cyclic paroxysm occur every 48 hours. Tertian mean that the symptoms occurs in three day cycles.

Plasmodium ovale causes a mild and very rarely fatal form of malaria. Similarly, Plasmodium malariae causes a mild infection. Plasmodium malariae is often referred to as ‘quartan’ malaria, meaning the fever and other symptoms run in four-day cycles.

Plasmodium falciparum strain is the most common type of malaria. It causes severe infections that kill millions of people every year worldwide. Clinically, Plasmodium falciparum are the most serious of the four, but it tends to run a shorter course without relapse.

Because of this risk of relapse, travelers to malarious areas are not allowed to donate blood for up to three years after returning.
Plasmodium and malaria 

What are the symptoms of malaria?

Malaria is an important cause of death and illness in children and adults, especially in tropical countries. 

Malaria is caused by infection of red blood cells with protozoan parasites of the genus Plasmodium. There are four species of plasmodium protozoa involved: vivax, falciparum, malariae, and ovale.

The parasites are inoculated into the human host by a feeding female anopheline mosquito.

The signs and symptoms of malaria might be vague, but fever is generally present. The first symptoms of malaria are non-specific and similar to the symptoms of a minor systemic viral illness.

Fever is the most prominent symptom which is often accompanied by headache, lassitude, fatique, back pain and muscle and joint aches, usually followed by chills, perspiration, anorexia, vomiting, diarrhea, nausea, increased sweating, and worsening malaise.

Cough and shortness of breath are common. When synchronous infections develop, each species of Plasmodium causes a characteristics pattern of periodic fever.

In addition to these symptoms of uncomplicated malaria, other manifestations may develop that signal severe malaria, which is almost due to Plasmodium falciparum.

These include confusion or drowsiness with prostration, together with severe manifestation such as cerebral malaria, severe anemia and others.

Untreated Plasmodium falciparum infection can lead to coma, renal failure, pulmonary edema and death. The other three forms of malaria (vivax, ovale and malariae) are rarely life threatening.
What are the symptoms of malaria?

The Quinine Story

The Quinine Story
Ever since is acceptance in 1640 as a proven remedy for the malaria disease, quinine has been the mainstay of malaria treatment and still is today.

Having observed Peruvians treating malaria successfully, Jesuit priests living in Peru returned to Europe with the bark of certain tree that, when boiled and the water drink, greatly improved the survival chances of a malaria victim.

Once introduced to Europe, cinchona (as it was then known) became the drug of choice after use by such famous patients as Charles II and the Archduke Leopold.

Despite its bitter taste and the fact that it sometimes produced deafness, nausea and vomiting, or that its method of action was still mysterious, quinine became known as a miraculous drug.
Its use was linked with serious risks including its association with blackwater fever, an occasional complication of malaria, but known to be one of the commonest causes of death among expatriates in Africa.

It is suspected that irregular doses of quinine used as a prophylactic may have caused this much feared disease.

Today, quinine taken with tetracycline is often the last drug used, after other drugs failed to quell malaria.
The Quinine Story

Malaria in Ancient Greece and Rome

Malaria in Ancient Greece and Rome
The ancient Greeks were well acquainted with malaria from about the year 500 BC when infected slaves may have carried the disease into Greece.

To a certain extend, malaria may well have contributed to the breakdown of ancient Greek civilization.

As early as 46 BC, Hippocrates described the malaria symptoms and differentiated between its various forms.

However, he incorrectly assumed that malaria was caused as a result of drinking stagnant water.

Malaria did not discriminate when choosing its victims. One famous victim was Alexander the Great.

Ancient Rome was seen to be vulnerable to the fever to the extent that Gei Febris, the fever goddess, as worshipped for her ability to cure the disease.

The fall of Rome has been attributed not only to hedonism and decadence, but also to the debilitating effects of the illness on its citizens.

Three emperors, Hadrian, Vespasian and Titus, are believed to have succumbed to malaria, while St Augustine is thought to have contracted it while carrying Christianity’s message from Rome to Britain.

Medieval Europe was well acquainted with malaria until land reclamation and improved drainage disrupted the mosquitoes’ breeding habits.

These habits were further discouraged inadvertently by the increased building of well lit and ventilated houses.
Malaria in Ancient Greece and Rome

Malaria - Infectious disease

Malaria - Infectious disease
Malaria kills three people every minute. Each year, it is thought that as many as 2.7 million people die from malaria and between 300 and 500 million suffer potentially fatal cases. The disease threatens 2.5 billion people, almost half the world’s population.

African countries south of the Sahara desert account for 90% of all clinical cases and nearly 90% of deaths caused by malaria. Children are most vulnerable to this major killer. In rural, tropical African areas, one child in 20 dies from malaria before he or she reaches the age of five years.

What is Malaria?
Malaria is a disease, caused by any of four species of parasite that is carried from person to person by a mosquito and transmitted by the bite of an infected female Anopheles mosquito.

Malaria is primarily a disease of the blood cells and small blood vessels. By causing the cells to become ‘sticky’ and eventually to burst, it causes blockages of the small blood vessels in the major organs of the body. This can cause severe disease and death – in case of the infection with the P. falciparum species of malaria, this can occur within 24 hrs of the disease first becoming evident.

Malaria caused by the other three parasite, namely Plasmodium vivax, P. ovale and P. malariae, is much milder and does not cause death, although they cause recurrent malaria than in itself is a debilitating disease.

The malaria parasite is found mostly in the tropical and subtropical regions of the world. Mosquito breeding is severely hampered in temperatures below 20 degree C. Optimal conditions for breeding are at temperatures around 30 degree C together with humidity levels of over 60%. Consequently, temperature and humidity largely dictate whether a country is likely to experience year-round malaria, seasonal malaria or localized break through.

The severity of malaria and its incidence is governed also by the immunity levels of the host, man. Immunity depends on constant exposure to the malaria-infected mosquito. Hence war and civil disturbances leading to an influx of non-immune workers, as well as tourism, all lead to the exposure of non immune to the malaria parasite.
Malaria - Infectious disease

Relapsing Malaria

Relapsing Malaria
Although uncommon, it is possible to develop a relapsing type of malaria months to even years after traveling to a malaria-infected country, even if you were taking the appropriate malaria medications to prevent the illness. Any returning traveler who develops a fever that lasts more than a few days requires prompt medical attention to screen for a malaria infection.

While malaria medications such as chloroquine, doxycycline, or mefloquine (Lariam) can prevent symptoms of acute malaria from developing by suppressing the infection in the bloodstream, they do not prevent relapses of infection caused by certain strains of the parasite that have a persistent liver phase.

Fortunately, the most common type of malaria is the P. falciparum strain that has no relapsing phase, so malaria medications will prevent any symptoms of this infection. However, it is necessary to continue such medications for four weeks after a possible exposure to ensure that the infection has run its course before the medication can be safely stopped.

Other strains of malaria such as P. vivax, ovale, or malariae can infect the liver and persist in a dormant state for months, or even up to several years, after exposure. Because of this risk of relapse, travelers to malarious areas are not allowed to donate blood for up to three years after returning.

In the unfortunate event that you do develop a relapsing case of malaria, it can be easily treated by suppressing the acute symptoms with chloroquine and then eradicating the liver infection with a medication called primaquine. This medication is more toxic and has more adverse effects than chloroquine, especially in individuals with an inherited deficiency in the blood enzyme G6PD that can be easily screened for with a simple blood test prior to treatment.

The best way to prevent relapsing malaria is to prevent getting infected in the first place. This is why it is very important to avoid mosquito bites by using insect repellents (containing at least 20-30% DEET) and mosquito netting in addition to taking malaria medications.

If you do develop a persistent fever and flu-like symptoms after returning from a malarious region, you need to be aware of the possibility of a malaria infection and should see a physician as soon as possible for further evaluation.
Relapsing Malaria