Investigations by WHO and Cambodia's health ministry have pinpointed the cause of a mystery outbreak that has killed more than 50 children this year. Abby Seiff reports from Phnom Penh.
A so-called “mystery disease” in Cambodia, which has seen an unusual number of young children die shortly after admission to hospital is due to a severe strain of hand, foot, and mouth disease and has been exacerbated by incorrect treatment, health authorities have concluded.
Since April, at least 60 children have been affected and more than 50 have died of the previously unknown illness. The bulk of the patients were younger than 3 years of age and most died within a day of being admitted to hospital.
In Phnom Penh on July 13, officials from the WHO and Cambodian Ministry of Health said investigations into the cause of the deaths determined that a “severe form” of hand, foot, and mouth disease (HFMD) was to blame. While most patients died before samples could be taken, most of those analysed tested positive for enterovirus 71 (EV—71)—a widespread and sometimes powerful strain of HFMD.
“This particular type, EV-71, was never seen before in Cambodia. It doesn't mean it wasn't here, just that we've never seen it”, Nima Asgari, a public health specialist at WHO said in a recent interview. “Considering it was seen in the region already—in China, Taiwan, Thailand, Malaysia—it's not surprising to see it here.”
Since the 1970s, millions of cases of HFMD have been seen in the region. Although the disease is generally mild and self-limiting (most patients recover within 10 days), outbreaks of the severest forms have led to deaths, especially among children. In the first 5 months of the year alone, 29 people in Vietnam have died from EV—71 and 244 in China, according to WHO.
“It's actually a very widespread disease, it's prevalent in many countries throughout the world”, Asgari told a group of reporters during a conference held at the Ministry of Health in Phnom Penh last week. “Usually it's a mild disease, usually it lasts about a week. But a very small number develop serious symptoms and need hospital treatment.”
In Cambodia, at least 54 children have died of the disease since April. In June, Beat Richner, director of the Kantha Bopha Children's Hospitals, alerted the Ministry of Health to the outbreak and called for an investigation noting that shortly before death, most of the patients' pulmonary alveoli were destroyed.
“They are suffering from an encephalitis and in the last 6 hours they develop a most severe pneumonia. The x-ray and CT are showing that the alveolars are destroyed within hours before passing away”, Richner documented at the time.
In its mild form, HFMD symptoms include fever, loss of appetite, and telltale blistering on the palms, soles, and mouth; but neurorespiratory problems—including convulsions and breathlessness—can occur in severe cases.
WHO and the Ministry of Health focused their investigation on 61 cases. Those who died ranged from between 3 months and 11 years old, though the median was 2 years old. 55% of patients were male.
Health officials concluded that the death rate was likely aggravated by chronic conditions such as malnutrition among the patients as well as mistreatment. “A significant number of cases had been treated with steroids at some point during their illness. Steroid use has been shown to worsen the condition of patients with EV—71”, the Ministry of Health and WHO said in a statement of their findings.
Health centres have been cautioned to avoid steroid treatment going forward, and the ministry will begin training courses for clinicians to manage patients with mild and severe forms of HFMD, said Sok Touch, the director of Cambodia's Communicable Disease Control Department. A widespread education campaign aimed at both the general population and health professionals is in the works as well. The disease is spread through direct contact and much of the public health focus has been on basic good hygiene practices, such as washing hands before eating or cooking and after bathing children.
At the moment, cases seem to have abated, but the Ministry of Health and WHO cautioned health-care providers to remain alert. A surveillance system to monitor neurorespiratory syndrome has been installed and health centres instructed to report mild cases of HFMD. Likely, the increased monitoring will result in an uptick of cases, health officials warned.
Currently, management of HFMD focuses on treating symptoms but vaccine research has been moving forward. At least two companies are now holding clinical trials for vaccines targeting EV—71. In June, Chinese biopharmaceutical company Sinovac said that they had vaccinated 10 000 infants as part of their phase 3 trial, while the US-based Inviragen in March announced positive immune responses during their phase 1 trial of INV21.