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Zika Isn't The Only Outbreak; Nigeria Struggles To Rein In Lassa Fever

In the world of public health, a lot of the media attention is focusing on the Zika outbreak in Latin America, but that's not the only disease on the rise. Nigeria is experiencing a smoldering Lassa fever outbreak. Since August 2015, almost 20 states have seen 175 confirmed and suspected cases and 101 deaths. The outbreak has poured into neighboring Benin, where 68 cases and 23 deaths have been reported.

Lassa fever, which is caused by an arenavirus, can affect multiple organs and cause bleeding in late stages. It's seen with some regularity every year in Nigeria. Since 2012, there have been 1,723 cases and 112 deaths, according to Nigeria's Center for Disease Control.

But in the current outbreak, Nigeria's ability to control the spread has been limited. There are concerns that patients are not seeking care in time either because they can't afford it, can't get to a health facility or don't recognize the symptoms as a sign of potentially serious illness. And so there is no true sense of the scope of the outbreak.

How is it possible that Nigeria, which not too long ago was widely praised for averting the Ebola outbreak, is having trouble controlling an outbreak that occurs almost seasonally? The Lassa outbreak reveals a few inherent cracks in Nigeria's system and raises good lessons in determining how a country or region can best respond to emerging infections.

Nigeria's response to Ebola was no doubt impressive, particularly given the fact that the spread of the disease in Lagos, the capital city and home to some 20 million people in Africa's most populous nation, would have been disastrous. On July 20, 2014, Patrick Sawyer, a Liberian national, arrived in Nigeria on a commercial flight. He was ill on the flight and was immediately taken to a private hospital. This imported case resulted in 20 confirmed infections and claimed eight lives.

Nigeria quickly made the diagnosis in the initial case of Ebola within its borders. That diagnosis allowed the mobilization of a public health infrastructure, which is much stronger than other countries in West Africa due to the investment made as part of the campaign to eradicate polio over the past 20 years. The polio campaign led to creation of emergency operations centers at the national and state levels. So Nigeria was able to effectively implement contact tracing and monitoring of exposed individuals. curtailing the outbreak in the country.

But Nigeria's ability to rapidly control Ebola was also related to a series of fortunate small coincidences rather than a foolproof system. The first of these breaks was the fact that Ebola was already rampant in neighboring countries before it arrived in Lagos, giving Nigeria the time to organize its response. Second, as opposed to the rampant, unchecked spread of Ebola in rural areas of Sierra Leone, Guinea and Liberia, Ebola first came to Nigeria through Lagos, and specifically, to a fairly well-quipped hospital with experienced doctors. An astute clinician, the late Dr. Stella Adadevoh, took care of Patrick Sawyer. She had the clinical acumen to suspect the diagnosis and ensure that her patient was tested. She herself later succumbed to the infection.

The Lassa virus, which is carried and transmitted by rodents for the most part, poses different challenges. Generally, 80 percent of those infected remain asymptomatic, while others can present with fever, weakness, nausea, vomiting, diarrhea and, in advanced cases, bleeding and coma. Overall mortality is 1 percent, while in severe cases it can be up to 15 percent. Most cases are mild and treatment is available with an antiviral medication, ribavirin, if given early in the disease. Interestingly, the death rate in the current outbreak is much higher than previously seen — almost 70 percent of the 83 laboratory confirmed cases died. The reasons are unclear.

The virus can be transmitted when food contaminated with rat excrement and urine is eaten or person-to-person if there is direct contact with the bodily fluids of an infected patient. As expected, poorer communities that are plagued by a larger rodent population are at higher risk, requiring government investment in rodent control (and causing a run on rat poison in local markets).

Public behavior change is also required to stop the spread of the disease, including hand washing, proper storage of food to keep rodents at bay and encouragement to seek care. Although the Nigerian government has been actively investing in radio jingles, posters and TV ads, the response from the public has been lackluster. That was not the case when Nigeria launched Ebola awareness campaigns. Perhaps Lassa does not seem to invoke the same sense of urgency in the general public.

Additionally, Nigerian hospitals, particularly in the public sector, are poorly equipped when it comes to infection control resources. Many patients actually buy the gloves for their doctors to use and keep them at their bedside. Hospitals and laboratories have been shown to be potential sources for the spread of not only Lassa, but many communicable diseases.

The Lassa outbreak also brings to the forefront the huge gap still to be covered in data collection and information management in the Nigerian public health system — an issue that still plagues most resource-limited countries. Cases may be missed when the patients were either not tested because they lived in a region that simply could not perform diagnostic exams or because their physician didn't report the case. Nigeria still needs to invest in modernization of its reporting system as well as engage physicians to actually report cases in a timely manner.

The biggest barrier by far is lack of access to medical care. For a case to be diagnosed, patients actually have to visit a health facility. In Nigeria, individuals must pay out-of-pocket for a large chunk of health care expenses, and more than 70 percent of the population lives in poverty. So many people delay seeking medical attention until it might be too late to make a difference — and meanwhile could be spreading disease to others.

On March 1, Nigerian press reported a cluster of three deaths from Lassa fever in Kaduna State in the northwest part of the country. A pregnant woman came in to a hospital for a caesarean section. She turned out to have Lassa fever and later died of the disease. The physician and nurse who cared for the woman became ill and died; they were diagnosed with Lassa after dying. These cases sadly exemplify the impact of delayed diagnosis. Had the pregnant woman been diagnosed, measures could have been put in place to protect the health care workers. These failures in the system outline the work ahead for Nigeria.

Olukemi Adekanmbi is an infectious diseases physician at University of Ibadan College Hospital in Nigeria.

Nahid Bhadelia is an infectious diseases physician at Boston Medical Center and Director of Infection Control and Medical Response at National Emerging Infectious Diseases Laboratories.

Copyright 2021 NPR. To see more, visit https://www.npr.org.

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