Outbreaks and do-overs

The current Ebola outbreak in Western Africa has been remarkable in terms of the number of cases and deaths; length and geographic extent of the outbreak; and its designation as a public health emergency of international concern. What could have been done differently to change the course of events? Thorough analyses of the outbreak and response will be done, and that will take time, but I think there are several things to consider.

More international assistance early in the outbreak. Early intervention is a mantra of modern medicine and public health, and indeed organizations like MSF and others brought impressive resources to bear early in the outbreak. Yet, transmission wasn't controlled and the epidemic grew. More resources are needed urgently. In hindsight, greater multilateral international aid earlier in the outbreak was needed, but how can nations know when NGO efforts need supplemental resources? Perhaps studying the early phases of this outbreak can suggest a way.

Better communication. The social disruption evident in this event is painfully clear and may have been intensified by the difficulty of communicating important public health messages. Anecdotes of healthcare workers being attacked and of disbelief that Ebola virus even exists are but two examples.

Balanced communications in the United States was mixed. On the one hand, many valid messages were circulated, including that Ebola poses little risk to the US general population. On the other hand, one expert told Congress that

We know how to stop Ebola with strict infection control practices, which are already in widespread use in American hospitals, and by stopping it at the source in Africa.

The second part of the statement is true enough: stopping an outbreak before it spreads is canonical in public health. However, the first part of the statement implies that strict infection control practice can prevent infection of healthcare workers and others in a hospital. That's a little problematic. If that were so, there wouldn't be problems with hospital-associated infection in the US.

By that calculus, for example, the 2011 outbreak of KPC-producing Klebsiella pneumoniae at the NIH shouldn't have occurred -- and yet the infection control practice in that event was meticulous from the initial presentation of the patient at the facility. What if an Ebola patient isn't recognized immediately when presenting at a US emergency department? And if a case is recognized, is infection control as it is actually carried out in practice likely to be effective? Such questions apply to any nosocomial pathogen, and I think it's important to ask: Given that KPC escaped a patient's room even with full precautions, why not Ebola?

Drug therapy. There are no approved treatments for, or vaccines against, Ebola virus infection. The development of new drugs is a scientifically, economically, and politically complex activity. The urgent need for new antibiotics, for example, has been discussed in connection with a large and growing need. The CDC recently reported that

Each year in the United States, at least 2 million people become infected with bacteria that are resistant to antibiotics and at least 23,000 people die each year as a direct result of these infections. Many more people die from other conditions that were complicated by an antibiotic-resistant infection. 

That's a massive burden of disease compared to the Ebola outbreak at present. Every case of any infection deserves effective management, but where is the incentive for drug development for Ebola and other exotic, low incidence infections? It is literally taking on act of Congress to help spur new antibiotic drug development in the US. Clearly drug therapies for Ebola would have been beneficial in this outbreak, and how to incentivize development seems an important question. In the absence of effective therapies and drug regimens, misinformation about bogus cures inevitably spreads and requires time and resources to counter.

Certainly these and related issues will be discussed and studied in depth in the coming months and years. Answers to the question of what could we do better next time must be found, because there will be future outbreaks of virulent emerging infections. How will we react?

(image source: CDC) 

Ebola: Thoughts on a public health disaster

The current outbreak of Ebola hemorrhagic fever in western Africa has been ongoing for months. It is a remarkable and tragic event. Sadly, there is no known cure, the case fatality proportion is high (historically 50-90%), and prevention is difficult in the areas where the virus is currently spreading.

Nations outside Africa are now recognizing the possibility of Ebola-infected travelers returning home. Importation of disease is a public health issue for other infections, such as measles, outbreaks of which are commonly sparked by visitors returning from areas where cases are prevalent. In the case of Ebola, one traveler died on the last leg of a West African trip, before returning home to Minnesota, so there's good reason to believe that importation could occur. It's probably unlikely, however, given the current level of awareness. Some African airlines, for example, have curtailed air service in affected areas and are screening passengers for signs of illness. International guidance on passenger screening is being evaluated as well. Moreover, CDC has issued interim guidance regarding Ebola for airline flight crews, cleaning personnel, and cargo personnel.

If an infected or infectious traveler does return, is it unlikely to result in the dramatic transmission currently observed in Africa. The current heightened awareness makes it very likely that travelers returning from affected areas would be evaluated for possible Ebola infection should they develop illness and present to a healthcare provider. The CDC has issued guidance advising healthcare workers to

be alert for signs and symptoms of EVD [Ebola virus disease] in patients with compatible illness who have a recent (within 21 days) travel history to countries where the outbreak is occurring, and should consider isolation of those patients meeting these criteria, pending diagnostic testing. 

Infection control procedures are standard and the necessary supplies are plentiful in Western hospitals, making it unlikely that an Ebola patient would cause secondary infections in healthcare settings.

Moreover, Ebola virus is much less transmissible than many other viruses. Measles virus, for example, has basic reproduction ratios in the range of 11-18, whereas those for Ebola have been estimated to be between 1-2. For comparison, the basic reproductive ratio for influenza is estimated to be 3-4, for rubella 6-7, and for chickenpox 10-12. The ratio for pertussis is similar to that of measles. One wonders what the basic reproduction ratio is for the current outbreak in Africa is (and if analytic approaches using social media might be helpful for estimating it).

Given that the current outbreak is so large compared to past outbreaks of Ebola, we might learn some lessons about this exotic disease. For example, are there transmission pathways that we don't know of at present? Aerosol transmission is thought to play only a minor role if any in transmission of human strains of Ebola virus, but perhaps new information will emerge from future epidemiological studies of the current outbreak.

What is for sure is that the events in Africa are a tremendous human tragedy. I hope that the desperate measures of closing schools and nonessential government services will help to control the spread of the virus. It isn't clear that it will.

(image source: Wikipedia)