Although the overall number of people who were infected with tuberculosis (TB) is down, the World Health Organization is concerned about a rise in drug-resistant versions of the disease.
In a new report issued Wednesday, the U.N. agency estimated there were about 8.7 million new cases of TB last year, down from about 8.8 million in 2010. The number of deaths was unchanged at about 1.4 million - making it the second-leading killer among infectious diseases after AIDS.
Other improvements include reaching the benchmarks set by the Millennium Developmental Goal (MDG) to halt and reverse the spread of TB by 2015. The MGD hopes to reduce TB mortality rates by 50 percent from rates reported in 1990. As of the 2012 report, the mortality rate has dropped 41 percent.
Eastern Europe and Central Asia had the highest numbers of drug-resistant TB, including 62 percent of previously treated patients in Uzbekistan and 75 percent of such cases in Belarus. Much of the disease's spread here is driven by intravenous drug users and weak health systems that don't identify and treat patients early enough.
About 40 percent of the world's TB cases are in India and China. They also have a rising number of drug-resistant cases even though both countries claim to treat about 90 percent of their TB patients. Last year, India reported several cases of totally resistant TB that were untreatable.
Other areas that have a high prevalence of TB include Africa, which has approximately 25 percent of the world's TB cases. The death rate is the highest in this continent. Part of the reason why TB is so dangerous in Africa is because the HIV epidemic is also fueling the spread of TB in sub-Saharan Africa. Patients with HIV often have weaker immune systems, making them more susceptible to catching TB. At least one-third of HIV patients also have TB and about one-quarter of deaths in people with HIV are due to TB.
While the fewest number of TB cases are found in North and South American and in Europe, the disease is on the rise in some cities including London, due largely to global travel patterns. The bacteria are spread easily in the air and people need only to inhale a few of the germs to be infected.
But no one knows for sure what the actual figures are since the WHO report said it was too expensive and complicated to measure the exact number of new TB cases every year. However, they reported that in 2012, 182 Member States and a total of 204 countries and territories that collectively have more than 99% of the world's TB cases reported their statistics.
WHO also said drug-resistant tuberculosis was spreading but acknowledged it didn't have enough data to know if those strains were getting more prevalent or not.
Drug-resistant TB is often the result of patients not being treated properly for regular TB; it is more expensive to treat and the drugs have worse side effects. WHO estimates that only 1 in 5 cases of drug-resistant TB are identified globally, meaning the others are spreading the disease without being treated.