Tournament of Pandemics: Chikungunia vs Tuberculosis - Part One

Tuberculosis has plagued humans for millennia, evidenced by tubercular decay in the spines of Egyptian mummies like this one from the British Museum. (photo credit: Wikipedia)

This is part of the ongoing Tournament of Pandemics.

Chikungunya owes its interesting name to the Makonde word meaning "that which bends up," thought to be a reference to the disease's arthritic symptom's, which often cause the afflicted to develope a stooped posture. The Chikungunya virus is transmitted to people by mosquitos, including the same Aedes aegypti mosquitoes species that can transmit malaria, dengue, or yellow fever. Chikungunya's symptoms resemble dengue, however, it is significantly less prevalent than either dengue, malaria, or yellow fever.

Three components of Chikungunia's strategy that we should look out for:

1. A few days ago Lisa Walker noted on this blog that global warming could affect the domain of many species of mosquitoes, potentially exposing large, new populations of people to yellow fever. The same concern applies to Chikungunia.

2. Chikungunya is thought to spread primarily through bites from Aedes aegypti mosquitoes; some strains appear to be mutating so that they can be transmitted by other types of mosquitoes.^[1]

Tuberculosis (TB) is caused by mycobacteria that usually attack the lungs.  The classic symptoms of tuberculosis include coughing with bloody sputum, fever, and weight loss. Treating TB is difficult; it requires long courses of multiple antibiotics.  Tuberculosis is spread through the air by coughing, sneezing, or spitting. One third of the world's current population is said to have been infected with M. tuberculosis, and new infections occur at a rate of one per second.^[2] In 2004, there were 14.6 million chronic active cases of TB, 8.9 million new cases, and 1.6 million deaths, mostly in the global south.^[2]

We should look out for TB's Social Strategy.

TB has been treatable for a long time, and today it primarily affects the poor. Fatalities are concentrated in the global south, and infections within countries like the U.S. are concentrated among poor and marginalized populations such as the homeless. TB's social strategy is to target the poor because they do not have the resources to fight back. TB has been largely eradicated from wealthy populations, producing a false sense of security while TB affects the voiceless majority of the world's communities.

The poor often receive partial or ineffective treatment, which helps TB develop resistance to antibiotics. The World Health Organization reports that approximately 50 million people worldwide are infected with multiple-drug resistant TB (MDR TB), with 79 percent of those cases resistant to three or more antibiotics. Extensively drug-resistant TB (XDR-TB) was identified in Africa in 2006. In the first widely publicized outbreak of extensively drug-resistant TB (XDR-TB), 53 South African patients were diagnosed and 52 of them died within days or weeks.^[3] We don't know exactly how prevalent XDR-TB is, but 49 countries have confirmed cases of XDR-TB, totaling about 40,000 cases per year.^[4] There are even more reasons that TB is scary, but I'll leave those to later rounds of the tournament.