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Mohamed H. Dahir (Chairman Pharmaceutical Association of Somaliland)
Antimicrobial resistance (continued)
Antimicrobial resistance is on the increase threatening our ability to treat some of the infectious diseases that cause most deaths. Diseases such as tuberculosis (TB), which was once thought to be under control, are becoming increasingly difficult to treat as medicines become less effective - steadily depleting the arsenal of drugs available.
Infectious disease still account for 45% of deaths in low-income countries and for almost one in two premature deaths worldwide. And most of these deaths (about 90%) are due to no more than six diseases: acute respiratory infections (mainly pneumonia), diarrhoeal disease, HIV/AIDS, TB, malaria and measles. Antimicrobial resistance is today challenging our ability to treat effectively at least four of these infections: acute respiratory infections, dearrhoeal disease, malaria and TB.
Chloroquine, for example - once the first-line treatment for malaria - is no longer effective in 81of the 92 countries where the disease is a public health problem. In some regions, over half of all cases of streptococcal pneumonia are resistant to penicillin and over 20% of new TB cases are now multi-drug - resistant.
To make matters worse, resistance is already emerging to anti-HIV drugs. There are reports of resistance to all currently marketed antiretroviral drugs. And resistance is also widespread among sexually - transmitted infections, such as gonorrhoea that enhance the spread of HIV.
But the problem does not end there. Hospital-acquired (nosocomial) infections, which account for 40.000 deaths a year in the United States alone, are almost always caused by drug-resistant microbes.
Food borne infections are also on the increase - promoting growing concern about drug resistance in pathogens such as salmonella and campylobacter. Meanwhile tropical diseases such as leishmaniasis and African trypanosomiasis, which haunt the poor and marginalized communities of the world, are becoming increasingly difficult to treat among people also infected with HIV. Treatment with the usual (and sometimes only) drug is increasingly ineffective.
How widespread is the problem?
Drug resistance is a global problem - affecting both developing and developed countries. Its spread is helped by the enormous increase in global travel and trade. Documented examples include:
- Cases of the drug-resistant gonorrhoea acquired by tourists visiting South-East Asia and transmitted among communities in Australia;
- Outbreaks of multidrug resistant TB in Western Europe traced back to Eastern European countries where TB control is poor;
- Two outbreaks of MRSA (methicillin-resistant staphylococcus aureus) hospital infection in Canada involving patients, who acquired the strain in India.
In addition, cases of drug resistant malaria occur among travelers returning to developed countries from malaria-endemic countries where resistance is high. These drug resistant infections will not spread in developed countries provided there are no mosquito vectors but global warming could change all that.
What is antimicrobial resistance?
When antimicrobial resistance occur it is the microbe (bacterium, virus, fungus or protozoan) that is resistant; not the drug nor the patient. Species of bacteria that are normally resistant to penicillin for example, can develop resistance to these drugs either through mutation (vertical transmission) or through acquisition from other bacteria of resistance genes (horizontal transmission). This dual means of acquiring resistance explains why the resistance trait can spread rapidly and replace a previously drug-susceptible population of bacteria.
To be continued next week.
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