Tropical Health Matters

Much of the discussion around global health and post-Millennium Development Goals focuses on non-communicable diseases (NCDs) including cardiovascular problems, diabetes, cancers and the the like.  While it is important to recognize that low income nations are not plagued with both communicable and non-communicable diseases, we do not want the greater focus on NCDs in richer countries to overshadow the problems of malaria, pneumonia, TB, diarrhea and other child killers in poorer countries.

A major reason for us not to lose focus on communicable diseases was recently reported from the Wellcome Trust on research they have supported in Malawi. The researchers found that the malaria parasite, Plasmodium falciparum, is able to “cause inflammation in blood vessel walls, making them more sticky so that the infected red blood cells can cling to the sides. Being able to stick to the blood vessels in vital organs allows the parasite to hide away from the immune system, a process called sequestration. When it occurs in the brain it causes a more severe form of the disease called cerebral malaria, associated with seizures, coma and sometimes death.”

The researchers also surmised that if this complication does not kill people in childhood, the damage to blood vessel walls can have more long lasting effects. In particular they noted that, “Chronic changes to the blood vessels like these could an important contributing factor to cardiovascular disease later in life.”

The link between malaria and Endemic Burkitt lymphoma (eBL) continues to be explored. Recently adding to this long history of eBL research, Peter Aka and colleagues reported that. “Anti–HRP-II (Plasmodium falciparum histidine-rich protein-II) antibodies suggest that recent malaria infection triggers the onset of eBL.”

In a review of intrauterine growth retardation (IUGR) Demicheva and Crispi observed that, “Several clinical and experimental studies showed that IUGR fetuses present signs of cardiac dysfunction in utero that persist postnatally and may condition higher cardiovascular risk later in life.” In endemic regions, malaria in pregnancy is a major cause of IUGR and thus low birth weight.

Preventing malaria therefore saves lives now and in the future. Ignoring malaria now adds greater burdens to the health system and national productivity tomorrow. We need to maintain our investments in malaria both globally and in and by endemic countries themselves.

UNICEF’s 2013 State of the World’s Children focuses on “Children with Disabilities.”  Some attention is paid to the role of communicable or infectious disease in the cause of disabilities and the need for children with disabilities to benefit from disease control services, just like any other child.

Of particular focus in the realm of infectious disease is recognition that, “… immunization is an important means of pre-empting diseases that lead to disabilities.” The Report goes on to explain for example, that, “More children than ever before are being reached. One consequence has been that the incidence of polio – which can lead to permanent muscle paralysis – fell from more than 350,000 cases in 1988 to 221 cases in 2012.”

Malaria as an infectious disease continues to exert a disabling effect on children in endemic countries. The Report does present a case study of children who spent several years in a residential home for children with mental disabilities in the Republic of Moldova, but it is also important to recognize that malaria and other infectious diseases can lead to such problems.

In reporting on neurological disease in Sub-Saharan Africa, Donald Silberberg and Elly Katabira explained that, “In addition to the hundreds of thousands of children who die each year from cerebral malaria, many more survive (often repeated attacks) and develop sequelae that have yet to be quantified. These include cognitive disorders and epilepsy.”

Likewise Ngoungou and colleagues after studying children with cerebral malaria in Mali found persistent neurological sequelae including, “ headaches, mental retardation, speech delay, bucco-facial dyspraxia, diplegia and frontal syndrome (one case each), dystonia (two cases), epilepsy (five cases) and behavior and attention disorders (15 cases).”

Immunization is of course a major tool in preventing disability, but we also need to examine the role other disease control efforts can play on preventing disability. Also as mentioned in the case of immunization above, we also need to ensure that all children with any kind of disability in a malaria endemic area promptly receive all necessary treatment and preventive interventions.

When calculating the burden of malaria, we often forget the longer term disabilities that persist after an acute episode. Specifically, Kariuki and co-researchers highlight that, “Falciparum malaria is an important cause of acute symptomatic seizures in children admitted to hospitals in sub-Saharan Africa, and these seizures are associated with neurological disabilities and epilepsy.”
In a new review in Neurology, Ngugi and colleagues report that …

“Our estimates suggest that the incidence of epilepsy in LMIC (low and middle income countries) is approximately twice that of HIC (high income countries) … The cause of the higher incidence in resource-poor compared to industrialized countries is likely to be multifactorial. The higher incidence of head trauma and of infections and infestations of the CNS (central nervous system) such as malaria, neurocysticercosis, and invasive bacterial infections may be important causes.”

Preventing malaria or treating malaria in a very timely manner is a crucial step in reducing the long term burden of disease in individuals and countries. Kariuki et al. note a challenge: “… it is difficult to determine the proportion of seizures attributable to malaria in endemic areas since a significant proportion of asymptomatic children have malaria parasitaemia.”

Kenya has been experiencing some intense malaria intervention over recent years.  This provides a setting where researchers have gotten a handle on the potential reduction in the burden of long term CNS disease because of malaria control activities. Among the findings Kariuki et al. report are that, “From 2002 to 2008, the incidence of all acute symptomatic seizures decreased by … 69.2% with 93.1% of this decrease in malaria-associated seizures.”

Malaria itself imposes major immediate costs on a community from direct service payments and indirect loss of work and of course from loss of life. We should not forget the lingering costs of severe malaria may degrade the educational and occupational capacity and opportunities of community members, leaving such endemic communities mired in poverty. Clearly malaria elimination is an essential contribution to national development.