By Dr. Kevin Ochieng Opondo

Warmer climates like those found in the tropics (Equator, Capricorn and Cancer) are not only favourable for human habitation but also to infectious diseases commonly referred to as ‘tropical diseases’.

Most tropical diseases are communicable, that is, they can be transmitted from one person to another and there are two main ways in which the diseases can be transmitted. Diseases like Ebola, HIV/AIDS and Tuberculosis are transmitted directly when a healthy individual comes into contact with an infected/sick person. Other diseases like malaria, yellow fever, leishmaniasis and elephantiasis are transmitted when a healthy person is bitten by an infected disease vector such as a mosquito.

For diseases transmitted directly from individual to individual, the rate at which a disease will spread within a healthy uninfected population depends largely on how frequent infected individuals come into contact with healthy uninfected persons. For those transmitted through a vector, the disease spreads more if infected insects bite many uninfected healthy individuals.

Human behaviour also plays an important role in the transmission of diseases; whether it is how we interact with the infected individuals or our local perception/beliefs on how a disease is transmitted or our health care seeking behaviours.

Why we must control diseases

These tropical diseases cause enormous burden on the health system in sub-Saharan Africa (SSA). For example, SSA countries spend an estimated $12 billion annually to control malaria with families using up to 25% of their income on malaria prevention and control.

Because of the high burden of these diseases, the few health care practitioners both in public and private health care facilities become overwhelmed and do not deliver quality care. Thus, the onus of disease control is to reduce the number of people who can get infected so that health care workers can provide high quality care to the few available cases.

Disease control programmes are designed and tailored based on how a particular disease is transmitted and mostly implemented in areas with high burden of the disease in focus.

Unsuccessful disease control programmes and human behaviour

Disease control should primarily be the responsibility of heath care systems but in SSA, the disease prevention and control arm of health care systems are not efficient and thus vertical disease control programmes have been set up by donor agencies and/or other non-governmental organizations (NGOs).

The disease control programmes utilize known tools/programmes that have been rigorously evaluated scientifically during efficacy studies and shown to work if implemented properly. During such efficacy studies, human participants and the local health care system involved are normally monitored closely. This ensures that the outcome being measured is accurately documented and that the outcome is not affected by improper implementation or lack of adherence by the community.

Although gains in disease control have just began to manifest, most control programmes have failed to yield the desired reduction in disease burden as estimated during efficacy trials. This could be due to a number of reasons.

Importantly, a tool or intervention strategy can be seen to work under efficacy trials but during implementation in the ‘real-world’ setting, the targeted community and health system are normally less involved, lowering expected impact of the tools.

Several examples can be given here; In the treatment and control of TB, HIV/AIDS, malaria etc, patients sometimes do not adhere to the prescribed drug dosage, take drugs before diagnosing the problem and general reluctance toward achieving disease-free state. Another example comes from the control of malaria where some of the insecticide treated bed nets are used for other activities other than protecting oneself from mosquito bites at night while sleeping.

This could be due to patient fatigue in complying with the long period of taking drugs which is a limitation of the tools available for disease control. Other reasons could be that a particular tool is not being implemented as desired leading to reduced impact.

Human behaviour and the magic bullet

Scientists have and continue to develop better tools and technologies but as this is ongoing, the community must step in to ensure that the ‘less-than-perfect’ tools available are utilized to the best achievable level.

That human behaviour is critical in disease control has long been recognized by disease control experts. Most control programmes today promote and encourage Behaviour Change Communication (BCC) by using social scientists and anthropologists in a bid to influence the uptake of these disease control interventions/tools.

However, even BCC as part of disease control is challenged by economic status of targeted communities. While disease control programmes aim to eradicate/eliminate disease from a particular setting, the main concern of most communities in developing countries are economical in nature; seeking money for food, basic needs and education etc.

We must all convince our communities in SSA that to be able to be productive in income generating activities, one must be healthy and this can only occur if we utilize the available control tools as scientists are working to develop better ones.

Disease control, especially in SSA, will remain an illusion if human behaviour remains unchanged. However, we can beat the magic of science by observing basic hygiene standards, seeking health care at the appropriate time, seeking medical advice before taking medication, adhering to prescribed drug dosages and using available tools appropriately.

Dr Opondo is Malaria Postdoctoral researcher and Disease control expert, Medical Research Council Unit The Gambia at the London School of Hygiene and Tropical Medicine, The Gambia