Imported Monkeypox, Singapore

Abstract

In May 2019, we investigated monkeypox in a traveler from Nigeria to Singapore. The public health response included rapid identification of contacts, use of quarantine, and postexposure smallpox vaccination. No secondary cases were identified. Countries should develop surveillance systems to detect emerging infectious diseases globally.

Keywords: Monkeypox; Nigeria; Singapore; communicable disease control; disease outbreaks; imported infectious diseases; monkeypox virus; orthopoxvirus; viruses; zoonoses.

Figure 1

Dermatologic features of monkeypox in a 38-year-old man, Singapore, 2019. A) Pustular lesions on the hand at the start of hospitalization. B, C) Resolving lesions with shedding of scabs of the hands (B) and feet (C) toward end of hospitalization (day 17). D, E) Crusting of right fourth finger lesion (D) and lesions at varying stages (vesicles and scabbing) on the left chest (E) on day 15 of hospitalization.

Figure 2

Transmission electron microscopy and maximum-likelihood phylogenetic tree of monkeypox virus in 38-year-old man, Singapore, 2019. A, B) Multiple brick-shaped particles, ranging from 230–290 nm by 130–240 nm, were observed from vesicle fluid under transmission electron microscopy. Tubular structures were observed with phosphotungstic acid stain (A), and a central ring-like depression was observed with gadolinium acetate stain (B). C) Phylogeny of monkeypox sequences, with the patient’s monkeypox strain in bold. All strains are identified by GenBank accession number, location, and year. The evolutionary relationships between monkeypox strains was determined based on 184,338 bases within the central core region of the monkeypox genome. The maximum-likelihood tree was created using RAxML (10) with γ-distributed rate differences and 1,000 bootstrap validation. Only bootstrap values >70% are displayed on the internal branches. Central African and West African clades are indicated. Scale bar indicates genetic distance between sequences.