The deadliest disease ever has been around for at least 20 million years.
It may have killed Alexander the Great, King Tut and at least six popes. Some sources claim that almost half of all humans that ever lived have been killed by it.
What is the name of this murderous menace? Malaria.
Malaria is a mosquito-borne infectious disease that affects both humans and other animals. Some mosquitos carry a parasitic protozoan of the genus Plasmodium. This is the killer.
Mosquitos are the vector, the carrier. If we look at mosquitos as a bomber, then Plasmodium is the bomb.
There are five species of the parasite that cause the disease. Of these, Plasmodium falciparum is the most deadly. According to the 2018 world malaria report, there were 219 million cases of malaria in 2017. From this number 435,000 infected people died.
Approximately 70% of malaria deaths occurred in children age 5 or younger.
The good news is that the number of deaths has decreased in recent year
Doctors divide malaria symptoms into two categories: Uncomplicated and severe malaria.
The Anopheles mosquito passes on malaria.
Malaria is passed on by the Anopheles mosquito.
A doctor would give this diagnosis when symptoms are present, but no symptoms occur that suggest severe infection or dysfunction of the vital organs.
This form can become severe malaria without treatment, or if the host has poor or no immunity.
Symptoms of uncomplicated malaria typically last 6 to 10 hours and recur every second day.
Some strains of the parasite can have a longer cycle or cause mixed symptoms.
As symptoms resemble those of flu, they may remain undiagnosed or misdiagnosed in areas where malaria is less common.
In uncomplicated malaria, symptoms progress as follows, through cold, hot, and sweating stages:
- a sensation of cold with shivering
- fever, headaches, and vomiting
- seizures sometimes occur in younger people with the disease
- sweats, followed by a return to normal temperature, with tiredness
- In areas where malaria is common, many people recognize the symptoms as malaria and treat themselves without visiting a doctor.
In severe malaria, clinical or laboratory evidence shows signs of vital organ dysfunction.
Symptoms of severe malaria include:
- fever and chills
- impaired consciousness
- prostration, or adopting a prone position
- multiple convulsions
- deep breathing and respiratory distress
- abnormal bleeding and signs of anemia
- clinical jaundice and evidence of vital organ dysfunction
- Severe malaria can be fatal without treatment.
Treatment aims to eliminate the Plasmodium parasite from the bloodstream.
Those without symptoms may be treated for infection to reduce the risk of disease transmission in the surrounding population.
The World Health Organization (WHO) recommends artemisinin-based combination therapy (ACT) to treat uncomplicated malaria.
Artemisinin is derived from the plant Artemisia annua, better known as sweet wormwood. It rapidly reduces the concentration of Plasmodium parasites in the bloodstream.
Practitioners often combine ACT with a partner drug. ACT aims to reduce the number of parasites within the first 3 days of infection, while the partner drugs eliminate the rest.
Expanding access to ACT treatment worldwide has helped reduce the impact of malaria, but the disease is becoming increasingly resistant to the effects of ACT.
In places where malaria is resistant to ACT, treatment must contain an effective partner drug.
The WHO has warned that no alternatives to artemisinin are likely to become available for several years.
Vector control is the main way to prevent and reduce malaria transmission. If coverage of vector control interventions within a specific area is high enough, then a measure of protection will be conferred across the community.
WHO recommends protection for all people at risk of malaria with effective malaria vector control. Two forms of vector control – insecticide-treated mosquito nets and indoor residual spraying – are effective in a wide range of circumstances.
Insecticide-treated mosquito nets
Sleeping under an insecticide-treated net (ITN) can reduce contact between mosquitoes and humans by providing both a physical barrier and an insecticidal effect. Population-wide protection can result from the killing of mosquitoes on a large scale where there is high access and usage of such nets within a community.
In 2017, about half of all people at risk of malaria in Africa were protected by an insecticide-treated net, compared to 29% in 2010. However, ITN coverage increased only marginally in the period 2015 to 2017.
Indoor spraying with residual insecticides
Indoor residual spraying (IRS) with insecticides is another powerful way to rapidly reduce malaria transmission. It involves spraying the inside of housing structures with an insecticide, typically once or twice per year. To confer significant community protection, IRS should be implemented at a high level of coverage.
Globally, IRS protection declined from a peak of 5% in 2010 to 3% in 2017, with decreases seen across all WHO regions. The declines in IRS coverage are occurring as countries switch from pyrethroid insecticides to more expensive alternatives to mitigate mosquito resistance to pyrethroids.
Antimalarial medicines can also be used to prevent malaria. For travellers, malaria can be prevented through chemoprophylaxis, which suppresses the blood stage of malaria infections, thereby preventing malaria disease. For pregnant women living in moderate-to-high transmission areas, WHO recommends intermittent preventive treatment with sulfadoxine-pyrimethamine, at each scheduled antenatal visit after the first trimester. Similarly, for infants living in high-transmission areas of Africa, 3 doses of intermittent preventive treatment with sulfadoxine-pyrimethamine are recommended, delivered alongside routine vaccinations.
Since 2012, WHO has recommended seasonal malaria chemoprevention as an additional malaria prevention strategy for areas of the Sahel sub-region of Africa. The strategy involves the administration of monthly courses of amodiaquine plus sulfadoxine-pyrimethamine to all children under 5 years of age during the high transmission season.
Since 2000, progress in malaria control has resulted primarily from expanded access to vector control interventions, particularly in sub-Saharan Africa. However, these gains are threatened by emerging resistance to insecticides among Anopheles mosquitoes. According to the latest World malaria report, 68 countries reported mosquito resistance to at least 1 of the 5 commonly-used insecticide classes in the period 2010-2017; among these countries, 57 reported resistance to 2 or more insecticide classes.
Despite the emergence and spread of mosquito resistance to pyrethroids (the only insecticide class used in ITNs), insecticide-treated nets continue to provide a substantial level of protection in most settings. This was evidenced in a large 5-country study coordinated by WHO between 2011 and 2016.
While the findings of this study are encouraging, WHO continues to highlight the urgent need for new and improved tools in the global response to malaria. To prevent an erosion of the impact of core vector control tools, WHO also underscores the critical need for all countries with ongoing malaria transmission to develop and apply effective insecticide resistance management strategies.
Diagnosis and treatment
Early diagnosis and treatment of malaria reduces disease and prevents deaths. It also contributes to reducing malaria transmission. The best available treatment, particularly for P. falciparum malaria, is artemisinin-based combination therapy (ACT).
WHO recommends that all cases of suspected malaria be confirmed using parasite-based diagnostic testing (either microscopy or rapid diagnostic test) before administering treatment. Results of parasitological confirmation can be available in 30 minutes or less. Treatment, solely on the basis of symptoms should only be considered when a parasitological diagnosis is not possible. More detailed recommendations are available in the “WHO Guidelines for the treatment of malaria”, third edition, published in April 2015.
Antimalarial drug resistance
Resistance to antimalarial medicines is a recurring problem. Resistance of P. falciparummalaria parasites to previous generations of medicines, such as chloroquine and sulfadoxine-pyrimethamine (SP), became widespread in the 1950s and 1960s, undermining malaria control efforts and reversing gains in child survival.
Protecting the efficacy of antimalarial medicines is critical to malaria control and elimination. Regular monitoring of drug efficacy is needed to inform treatment policies in malaria-endemic countries, and to ensure early detection of, and response to, drug resistance.
In 2013, WHO launched the Emergency response to artemisinin resistance (ERAR) in the Greater Mekong Subregion (GMS), a high-level plan of attack to contain the spread of drug-resistant parasites and to provide life-saving tools for all populations at risk of malaria. But even as this work was under way, additional pockets of resistance emerged independently in new geographic areas of the subregion. In parallel, there were reports of increased resistance to ACT partner drugs in some settings. A new approach was needed to keep pace with the changing malaria landscape.
At the World Health Assembly in May 2015, WHO launched the Strategy for malaria elimination in the greater mekong subregion (2015–2030) , which was endorsed by all the countries in the subregion. Urging immediate action, the strategy calls for the elimination of all species of human malaria across the region by 2030, with priority action targeted to areas where multidrug resistant malaria has taken root.
With technical guidance from WHO, all countries in the region have developed national malaria elimination plans. Together with partners, WHO is providing ongoing support for country elimination efforts through the Mekong Malaria Elimination programme, an initiative that evolved from the ERAR.
Surveillance entails tracking of the disease and programmatic responses, and taking action based on the data received. Currently, many countries with a high burden of malaria have weak surveillance systems and are not in a position to assess disease distribution and trends, making it difficult to optimize responses and respond to outbreaks.
Effective surveillance is required at all points on the path to malaria elimination. Stronger malaria surveillance systems are urgently needed to enable a timely and effective malaria response in endemic regions, to prevent outbreaks and resurgences, to track progress, and to hold governments and the global malaria community accountable.
In March 2018, WHO released a reference manual on malaria surveillance, monitoring and evaluation. The manual provides information on global surveillance standards and guides countries in their efforts to strengthen surveillance systems.
Malaria elimination is defined as the interruption of local transmission of a specified malaria parasite species in a defined geographical area as a result of deliberate activities. Continued measures are required to prevent re-establishment of transmission.
Malaria eradication is defined as the permanent reduction to zero of the worldwide incidence of malaria infection caused by human malaria parasites as a result of deliberate activities. Interventions are no longer required once eradication has been achieved.
Countries that have achieved at least 3 consecutive years of 0 local cases of malaria are eligible to apply for the WHO certification of malaria elimination. In recent years, 9 countries have been certified by the WHO Director-General as having eliminated malaria: United Arab Emirates (2007), Morocco (2010), Turkmenistan (2010), Armenia (2011), Maldives (2015), Sri Lanka (2016), Kyrgyzstan (2016), Paraguay (2018) and Uzbekistan (2018). The WHO Framework for Malaria Elimination (2017) provides a detailed set of tools and strategies for achieving and maintaining elimination.
Vaccines against malaria
RTS,S/AS01 (RTS,S) is the first and, to date, the only vaccine to show partial protection against malaria in young children. It acts against P. falciparum, the most deadly malaria parasite globally and the most prevalent in Africa. Among children who received 4 doses in large-scale clinical trials, the vaccine prevented approximately 4 in 10 cases of malaria over a 4-year period.
In view of its public health potential, WHO’s top advisory bodies for malaria and immunization have jointly recommended phased introduction of the vaccine in selected areas of sub-Saharan Africa. The vaccine will be introduced in 3 pilot countries – Ghana, Kenya and Malawi – in 2019.
The pilot programme will address several outstanding questions related to the use of the vaccine in real-life settings. It will be critical for understanding how best to deliver the required four doses of RTS,S; the vaccine’s potential role in reducing childhood deaths; and its safety in the context of routine use.
This WHO-coordinated programme is a collaborative effort with ministries of health in Ghana, Kenya and Malawi and a range of in-country and international partners, including PATH, a non-profit organization, and GSK, the vaccine developer and manufacturer.