Largest Marburg outbreak may have peaked, WHO officials say

May 2005

The largest Marburg outbreak in history may have finally peaked, said public health officials during a teleconference for reporters. Fear, superstition and lack of infrastructure thwarted international efforts to gain control of this outbreak, they added.

So far, 273 cases and 253 deaths have been reported in Angola. However, the average number of new cases have dropped from 35 to 15 per week.

“This is good news. But it doesn’t mean that the outbreak is over. In fact, this may be the most dangerous time. In past outbreaks, we know that the perception that the battle has been won had led to people lowering their guard,” said Dr. Fatoumata Diallo, the WHO representative in Angola. “As long as there remains one single case of Marburg virus in Angola, we will not be able to say that the situation is completely under control.”

The epicenter of the outbreak is Uige Province, where most of the cases occurred, said Dr. Nestor Ndayimiridje, international team leader for the response team in Uige, which has had 253 cases and 233 fatalities. In addition, officials are following more than 300 close contacts.

“In terms of numbers of contacts, we are following more than 300 people. In terms of trends, at the beginning, it seems it was mainly children under 1 year of age. And since week 10, we have seen more cases in adults, and now we have around, I would say 60% to 70% of adult [cases],” added Pierre Formenty, PhD, a medical officer from France.

WHO said the disease characteristics and the conditions in Angola have been an “extreme test” of international capability to control emerging diseases. International officials have been in Angola for more than one month and the outbreak is only just beginning to abate.

This outbreak is the largest and deadliest on record for this rare disease; the case-fatality rate is higher than 90%. The outbreaks of the closely related Ebola have shown mortality rates ranging from 53% to 88%. The Congolese outbreak of Marburg, which ran from 1998 through 2000, had a case-fatality of 83%, according to WHO.

Two factors make the rapid detection of Marburg fever difficult: the disease is rare and is similar in the early stages to other infectious diseases. Neither the source nor the date of the initial cases can be determined with certainty, but the number of cases began rising in March, WHO said.

On March 21, Marburg virus was detected in patient samples sent to the CDC, and the Ministry of Health in Angola requested WHO assistance. The operational response began the following day.

“We have had a truly international response, including Portuguese-speaking social mobilization experts from Brazil, from Mozambique and from the Democratic Republic of Congo, a medical anthropologist from France, critical laboratory workers from Canada, surveillance people from Italy, Switzerland and Germany, a data manager from Kosovo, infection control from South Africa, and so on. We also have had regional, dedicated staff from WHO,” said Diallo.

The measures needed to end the Angolan outbreak are straightforward: rapid detection and isolation of patients, tracing and management of close contacts, infection control in hospitals and protective clothing for staff. These measures would interrupt the chain of transmission, WHO officials said in a release.

However, this response was complicated by the community reaction. People refused to report cases and hid bodies from authorities. In addition, many used local healers – not physicians – who are giving injections that could be spreading the virus, Formenty said. Health authorities do not know what is in the injections, but the needles themselves can be a source of transmission, just as they are for HIV.

One can understand being suspicious after seeing what happened to sick friends and relatives: few patients with confirmed Marburg have survived during this outbreak and most hospitalized patients have died within two days of being admitted. Families see public health workers suited in protective gear, taking away loved ones, who inevitably die.

Ndayimiridje said fear was rampant. “This was mainly the community response because of fear, since the epidemic is something which is new in the country. Now, the community response has improved,” he said.

Formenty said public health workers in crisis mode were not always sympathetic to the families. They have learned to be more responsive and transparent.

For instance, “we have stopped the use of plastic sheeting in the isolation wards,” he said because people linked the plastic to death.

“If you have plastic around the place, it shows that you are going to kill them,” he said. “So, we are using fences to isolate the ward, but these fences are 1.5 meters high, so that people can come and see what we are doing and see that we are not killing the people. We try to develop this transparency approach of the work of the medical team in the isolation ward.”

Although community attitudes are improving, hostility toward the health workers remains a concern, but volunteers are trying to overcome this.

“With the aggressive social mobilization that was established from April 9, we have seen that the communities are notifying us of the dead bodies in the suspected cases, which has helped to get more acceptability of the Marburg treatment center,” said Ndayimiridje.

Conditions in Angola, a country weakened by almost three decades of civil war, have presented additional challenges. The availability of safe water and electricity are intermittent. The infrastructures, including those for communications and transportation, are weak.

Ndayimiridje said that health workers have set up fever clinics as a first response measure. “Our team has established a fever ward which is called the safety room to try to screen the cases and try to detect suspected Marburg cases and confirm them. So through that, we will be able to get more patients going into isolation wards, which were not accepted by communities before because of the high mortality rate that was observed. But through the screening mechanism of the established safety room we will get more patients and screen more patients for the Marburg treatment center.”

Diallo said the response is moving into another important phase with local health officials taking a stronger role. They are involved in infection control, surveillance and contact follow-up. “We recognize that no outbreak can be successfully contained without the participation of local communities,” Diallo said.

Fortunately, spread of the disease beyond Uige Province has been limited, and the international risk is low. The CDC said there are no U.S. travel restrictions to Uganda.