Posts or Comments 01 March 2021

Monthly Archive for "January 2018"

Uncategorized Bill Brieger | 31 Jan 2018

Climate Changes Many Things Including Malaria

Heavy rains, flooding and malaria

A changing climate, even a warming climate, does not directly translate into greater malaria transmission.[i] Lafferty and Mordecai explain that we need a need “a greater appreciation for the economic and environmental factors driving infectious diseases,” as these have their own impact on transmission.[ii] Climate change effects occur in parallel to “changes such as land conversion, urbanization, species assemblages, host movement, and demography.” This wider ecological understanding is needed to “predict which diseases are most likely to emerge where, so that public health agencies can best direct limited disease control resources.”

As the WHO framework for malaria elimination stresses, [iii] “Most countries have diverse transmission intensity, and factors such as ecology, immunity, vector behaviour, social factors and health system characteristics influence both the diversity of transmission and the effectiveness of tools, intervention packages and strategies in each locality.” The Framework goes further to encourage strategic planning and interventions appropriate for the diverse settings or strata within a country. What climate change implies is that the nature of malaria transmission in these strata will change as temperature, rainfall, humidity and human response change. Countries not only need to adapt malaria activities to existing strata, but also be alert to changes in transmission and thus changes needed in strategies.

Increased or decreased vector control activities would be one example of changes that are needed in response to climate, vector habitat and transmission changes. “The receptivity of an area (to vector control interventions) is not static but is affected by determinants such as environmental and climate factors.” Case detection will become even more crucial as transmission drops and the success of elimination programs depends on identifying, tracing and responding to remaining cases promptly and accurately.

The landscape for malaria control and elimination is shifting in part because of the success of interventions since the dawn of Roll Bank Malaria in 1998.  As we have shown here, there may also be shifts due to climate change. Of great concern is the shifts that expose new and more vulnerable populations, such as those in the East Africa highlands to the threat of malaria. National Malaria Programs need strong surveillance efforts that monitor disease, vectors and climate, and be ready to respond.

[Excerpted from Africa Health]

[i] World Health Organization. Climate change and health. Fact sheet. Updated July 2017.

[ii] Lafferty KD, Mordecai EA. The rise and fall of infectious disease in a warmer world. F1000Research 2016, 5(F1000 Faculty Rev):2040 last updated: 19 AUG 2016. (doi: 10.12688/f1000research.8766.1).

[iii] Global Malaria Program. A framework for malaria elimination. World Health Organization 2017, ISBN 978-92-4-151198-8.

Elimination &Eradication &NTDs Bill Brieger | 26 Jan 2018

The Long and Winding Worm, 1986-2018

Recent reports draw attention that Guinea Worm persisted in small numbers in 2017 in two countries, Chad and Ethiopia. Mali and South Sudan were the only other two countries monitored because of recent cases, but each reported none for 2017.

Guinea Worm Wrap-Up #251

We recall that 32 and 23 years have passed since the challenge to eradicate the disease was posed and the hoped for date of eradication was to be achieved. There is no doubt that the 30 cases reported in 2017 is a gigantic drop from the 3.5 million estimated globally when the war on the worm started in 1986.

To date eradication has been achieved for only small pox (though its reemergence from labs as a potential biological war agent is feared). Could it return as global warming melts permafrost (and bodies) in the permafrost of northern latitudes?

Besides Guinea Worm, only polio and malaria have received calls for eradication (malaria for the second time in history). One wonders if even small pox could be eradicated in today’s world of conflicted and failed states – the last case of smallpox was in Somalia. Both Ethiopia and Chad border South Sudan’s civil conflicts.

What had made guinea worm, like smallpox, imminently eradicable was the fact that humans were the main reservoirs of infection (not counting the defenseless crustacean, the cyclops, that served as an intermediate host for work larvae). That has not changed. WHO observed that in Ethiopia both baboons and dogs have been infected with guinea worm in the same communities where humans suffer from the disease. While it was possible to ‘contain’ the infection in dogs, that is preventing them from contaminating water supplies, it was not surprisingly difficult to do the same for baboons. The dog problem has existed in Chad for at least 5 years.

Another problem in Ethiopia was the infection of seasonal laborers who could potentially take the disease back to other areas of the country. Although a system of rewards had been put in place this did not lead to the timely identification of all cases by either community members or health workers.

The road to disease eradication is clearly not a straight line from A to B. The twists and turns should be expected as time passes because ideally an eradication should be a short-term effort that is time-limited in order to provide a clear focus and adequate funding on the end goal.

What are the implications for malaria and polio? Conflict led to the hiding of polio cases in Nigeria and longer term efforts allowed vaccine derived poliovirus to emerge. Malaria is now found in Monkeys in Malaysia and Brazil, and parasite resistance to medicines and vector resistance to pesticides threatens effective interventions.

Time is not a commodity that favors eradication. In these days of plateauing financial support for global health, the call for eradicating deadly and economically debilitating infections needs to be louder.