January 10, 2016

Research Roundup: Ebola treatments, drug-resistant gonorrhea, and zoonotic tuberculosis

Senior Program Assistant

A recent clinical trial found that convalescent plasma therapy, a treatment in which the blood plasma is taken from survivors of a disease and used to treat current patients, did not prove to be effective against Ebola. The blood plasma of survivors includes antibodies against the pathogen, in this case the Ebola virus, which can boost a patient’s immune response. Convalescent plasma therapy has been used for more than 100 years, and was first used against Ebola in 1976. In the trial, plasma therapy was used to treat 84 patients, and an additional 418 patients that had been treated at the same facility served as the control group. The treatment reduced death rates by a mere 2.6 percent, and the result was not statistically significant. However, the trial did demonstrate that the collection and transfusion of blood plasma from survivors to patients was safe and feasible in low-resource settings. During the trial, the therapy did appear to be particularly effective in pregnant women and infants, however, the sample size was too small to confirm. Plasma samples from the trial will now be sent to a facility in France where researchers will assess the concentration of antibodies in the samples to determine if the quantity of antibodies affected survival rates.

A recent study suggests that the antimalarial artesunate/amodiaquine (ASAQ) could be more effective against Ebola than artemether/lumefantrine (AL), an antimalarial previously used to treat Ebola, due to the diseases’ overlapping symptoms. During the outbreak, a Médecins Sans Frontières treatment center in Liberia initially used AL to treat patients, however, after running out of AL, they began to use ASAQ. The death rate for patients receiving ASAQ was 50.7 percent, compared to 64.4 percent of patients on AL. While ASAQ appears to be a promising treatment, additional trials are needed to investigate ASAQ’s efficacy in reducing Ebola mortality.

Strains of the bacteria responsible for the sexually transmitted infection gonorrhea are becoming increasingly resistant to antibiotics. In the United States, one-third of gonorrhea cases are resistant to at least one antibiotic. Public officials, both in the United States and Britain, are urging doctors to follow prescription recommendations to prevent the spread of drug-resistant strains. In Britain, many doctors continue to prescribe ciprofloxacin, which has not been recommended for gonorrhea in 10 years. In the United States, doctors have historically prescribed ceftriaxone, however, between 2011 and 2013—after new guidelines led doctors to prescribe ceftriaxone in combination with azithromycin—ceftriaxone-resistant strains decreased by two-thirds from 1.4 percent to .4 percent of cases.

Cow standing in a grassy field.
Cow standing in a grassy field. (Photo: PATH/Eric Becker)

The bacteria Mycobacterium bovis, which causes bovine tuberculosis (TB), is a rising cause of human TB, and while it’s responsible for just 1.4 percent of cases globally (and 1.5 percent of cases in America), up to 44 percent of TB-infected Latino Americans have the bovine version. Bovine TB is found in two dozen mammal species and is usually transmitted to humans through unpasteurized dairy products. In Mexico, 40 percent of dairy products are unpasteurized, and consequently the proportion of bovine TB cases among Americans are highest along the US-Mexico border. Two-thirds of bovine cases in the United States are extra-pulmonary—outside of the lungs—and are consequently undetectable by standard diagnostic techniques. The remaining third, confined to the lungs, could presumably be spread between humans through coughing or sneezing.