Malaria awareness

CEBU, Philippines – November is Malaria Awareness Month. The disease has since been less dreaded in the country - but not a bit less lethal. While it is no longer as much heard of these days, the risk of malaria has not diminished.

The World Health Organization (WHO) describes malaria as a life-threatening disease caused by parasites that are transmitted to people through the bites of infected female mosquitoes. About 3.2 billion people - almost half of the world's population - are at risk of the disease.

Malaria is preventable and curable, and increased efforts are dramatically reducing the malaria burden in many places. Between 2000 and 2015, malaria cases have gone down by 37 percent globally. In the same period, malaria death rates fell by 60 percent globally among all age groups, and by 65 percent among children under five years of age.

Plasmodium parasites cause malaria. The parasites are spread to people through the bites of infected female Anopheles mosquitoes, called "malaria vectors." The important vectors bite between dusk and dawn.

Malaria symptoms appear seven days or more (usually 10 to15 days) after the infective mosquito bite. The first symptoms - fever, headache, chills and vomiting - may be mild and difficult to recognize as malaria. If not treated within 24 hours, P. falciparum malaria can progress to severe illness, often leading to death.

Children with severe malaria frequently develop one or more of the following symptoms: severe anaemia, respiratory distress in relation to metabolic acidosis, or cerebral malaria. In adults, multi-organ involvement is also frequent. In malaria endemic areas, people may develop partial immunity, allowing infections to occur without symptoms.

While the most malaria cases and deaths occur in sub-Saharan Africa, other places in the world are also at risk, like Asia, Latin America, and, to a lesser extent the Middle East and parts of Europe. Up to this year, 97 countries and territories had ongoing malaria transmission, despite efforts to totally quell the disease.

Certain people are at considerably higher risk of contracting malaria, and developing severe disease, than others. These include infants, children under five years of age, pregnant women and patients with HIV/AIDS, as well as non-immune migrants, mobile populations and travelers to known malaria hotspots.

Increased awareness helps. An estimated 6.2 million malaria deaths have been averted globally since 2000, according to WHO. Public awareness on malaria often leads to precaution and prevention.

Anopheles mosquitoes lay their eggs in water, which hatch into larvae, eventually emerging as adult mosquitoes. The female mosquitoes seek a blood meal to nurture their eggs. Each species of Anopheles mosquito has its own preferred aquatic habitat; for example, some prefer small, shallow collections of fresh water, such as puddles and hoof prints, which are abundant during the rainy season in tropical countries.

Transmission is more intense in places where the mosquito lifespan is longer (so that the parasite has time to complete its development inside the mosquito) and where it prefers to bite humans rather than other animals. The long lifespan and strong human-biting habit of the African vector species is the main reason why nearly 90 percent of the world's malaria cases are in Africa.

Transmission also depends on climatic conditions that may affect the number and survival of mosquitoes, such as rainfall patterns, temperature and humidity. In many places, transmission is seasonal, with the peak during and just after the rainy season. Malaria epidemics can occur when climate and other conditions suddenly favor transmission, in areas where people have little or no immunity to malaria. Such epidemics can also occur when people with low immunity move into areas with intense malaria transmission.

Human immunity is another important factor, especially among adults in areas of moderate or intense transmission conditions. Partial immunity is developed over years of exposure, and while it never provides complete protection, it does reduce the risk that malaria infection will cause severe disease. For this reason, most malaria deaths in Africa occur in young children, whereas in areas with less transmission and low immunity, all age groups are at risk.

Early diagnosis and treatment of malaria reduces disease and prevents deaths. It also reduces malaria transmission. The best available treatment, particularly for P. falciparum malaria, is artemisinin-based combination therapy or ACT.

But there is the problem of resistance to anti-malarial medicines. Resistance of P. falciparum to previous generations of medicines became widespread in the 70s and 80s, undermining malaria control efforts and reversing gains in child survival. Hence, WHO recommends the routine monitoring of anti-malarial drug resistance, and supports countries to strengthen their efforts in this important area of work.

Various malaria elimination efforts are either in place or vigorously encouraged. These are very necessary efforts, considering the seriousness of the disease. But it may still be long before the malaria threat is totally contained.

In the meantime, awareness and vigilance are very important tools. By being aware, people become more careful. By being vigilant they are ready to topple the threat.