Course Management of Prevalent Infections in Children Following a Disaster

Characteristics and incidence of malaria

Malaria is caused by a protozoan blood parasite (Plasmodium) transmitted by the Anopheline mosquito as a vector. The infection produces a clinical syndrome that ranges in severity depending on the species of the parasite and the immune status of the individual. Malaria caused by lasmodium vivax, P. malariae, and P. ovale usually results in mild or moderate disease. P. falciparum often results in a life threatening disease and severe anemia. The emergence of resistant artemisinin P. falciparum is becoming a global problem since WHO has recommended this core compound for treatment of uncomplicated malaria.

According to WHO (December 2014 update), in 2013 there were 198 million malaria cases and an estimated 584,000 deaths due to malaria. Most deaths occur in children under 5 years of age. 

Children who have been recently treated for malaria can contract malaria again. Malaria immunity following an infection is at best partial, and protects only against the species causing the initial infection. Children can therefore be infected with a different malaria species in regions having more than one prevalent species or they can be reinfected with the same species. A relapse or recrudescence of an existing infection can be related to a failure to eradicate a parasite that has become drug-resistant or to a patient’s failure to adhere to a therapeutic regimen.

Malaria occurs in areas of Southeast Asia and Latin America where transmission is seasonal or limited to specific focal areas, so the general population does not have a high level of acquired immunity. Both children and adults in these areas are at high risk for severe disease. Malaria also occurs in areas of Africa where the disease is widespread and endemic. It gen­erates high levels of acquired immunity in adults, but young children are at higher risk for severe disease. Most Anopheline mosquitoes are not well adapted to urban environments or places about 3,900 ft (1,200 m) above sea level. Consequently, individuals living within a malaria endemic country may be nonimmune if they live within one of these malaria-free “pockets.” When these nonimmune people are displaced from their communities to areas with high malaria transmission, the consequences can be a devastating malaria epidemic.

Malaria diagnostic tests

Both rapid diagnostic tests (RDTs) and Microscopy can be used to diagnose malaria. In an emergency response, the high patient load and absence or low number of skilled laboratory technicians often leads to high reliance on rapid diagnostic tests that can be done by clinicians in clinics or at the bed-side. Microscopy involves identifying the parasite in stained (Giemsa or Wright) blood smears. A blood sample is easily obtained from a finger prick. After a drop is placed on a clean labeled glass slide, spread it with another glass slide into a thin blood smear. Thick smears are obtained by placing some drops of blood on a glass slide and spreading the drops with the corner of another glass slide. Dry the resulting smear without fixation. Since thick smears allow the examination of more blood than thin smears, they facilitate the detection of the parasite in cases of low-grade parasitemia. Serial samples at 6- to 12-hour intervals for 48 hours may be necessary to identify the parasite. Species identification in the field setting is important only for discriminating between P. falciparum and other species because the treatment can be different.

The quantitative level of parasitemia is a prognostic marker; >5% of parasitized red blood cells is associated with high mortality. Low-grade parasitemia related to partial immunity or treatment can result in a negative smear. Even patients with cerebral malaria can be smear-negative at presentation.

Therefore the clinical diagnosis of malaria based on signs and symptoms tends to be highly inaccurate. While It is preferable to have rapid diagnostic tests or microscopy to rule out malaria in patients that present with febrile illness living in an area with malaria. In the absence of available diagnostic testing begin treatment when the clinical history and presentation are consistent with malaria.

However, it is also important to acknowledge that malaria can coexist with other conditions that cause fever as well as predispose to other intracellular pathogens. In diagnostic the absence of specific tests, empiric treatment of any serious febrile illness should include coverage for malaria, as well as other pathogens.

Surveillance

In areas with endemic malaria, determine the proportion of febrile illness in a camp or settlement attributable to malaria by comparing malaria diagnostic tests from a sample of patients under 5 years of age who have a history of recent fever with an equal number of patients without fever. Comparing the prevalence of malaria parasites in the blood of these two groups gives an indication of how much malaria is contributing to acute febrile illness in the general population.This will be useful for the empiric management of other patients.

Chemoprophylaxis

It has been used to limit epidemics in groups without immunity that are relocated to a high malaria transmission area and to reduce mortality among targeted populations, such as malnourished children under 5 years of age. Massive Seasonal Chemoprevention has been done in emergency contexts. Recent experience in Mali, Niger, Central African Republic and Sierra Leone in the middle of the Ebola epidemic, are good example of success of this strategy. Adequate infrastructure and resources must be available to implement a preventive chemoprophylaxis program for a targeted population. Efforts must be coordinated with local and national public health authorities. Recent trials of malaria vaccines show moderate effectiveness and can be considered in selective situations.

Clinical presentation

There are two distinct clinical malaria presentations: uncomplicated malaria and severe, complicated malaria. Uncomplicated malaria presents with fever, chills, headaches, myalgias, diarrhea and anemia. Classic malaria fever has been described as paroxysms of fevers and shaking chills lasting 8 to 12 hours, every 2 to 3 days. During the afebrile period, fever disappears and the subject feels relatively well (depending on the species). The febrile paroxysms coincide with the cyclical release of parasites from ruptured red blood cells; the afebrile period coincides with the quiet growth of the parasite in a new population of red blood cells. Partially immune individuals may have a non-specific fever pattern.

Malaria is considered to be very severe if parasitemia is >5% or any of following complications are present: prostration (patient unable to sit or walk), multiple convulsions, impaired consciousness not attributable to another cause, abnormal bleeding, meningeal signs, or jaundice. According to IMCI the presence of any danger sign or a stiff neck leads to a very severe febrile disease classification.

Cerebral malaria is associated with signs of acute encephalopathy (coma and seizures), normal cerebrospinal fluid (CSF), and no other identifiable cause (meningitis, viral encephalitis, metabolic abnormalities). Cerebral malaria mortality varies from 15% to 50%.