A brief description of the epidemiology of dengue in Dili, Timor-Leste, 2018-2022.

Abstract: Dengue virus (DENV) infection causes 390 million infections per year and 40,000 deaths globally. It is endemic in many countries in Asia, Africa, the Americas, the Caribbean, and Oceania. Dengue is endemic in Timor-Leste year-round, but peak transmission occurs during the rainy season. We briefly describe the epidemiology of DENV in the Municipality of Dili between 2018 and 2022. There were 6,234 cases notified, with a mean annual incidence rate of 330 cases per 100,000 population. There were 55 deaths (case fatality rate 0.9%). The peak annual incidence (3,904 cases) occurred in 2022 after an outbreak was declared in January of that year; this outbreak included 760 cases of dengue haemorrhagic fever and 35 deaths. The number of outbreak cases requiring hospital treatment exceeded the usual capacity, but facilities established for coronavirus disease 2019 (COVID-19) isolation and treatment were repurposed to meet this demand. Existing strategies of vector control, minimising breeding sites and promoting early presentation for treatment should continue, as should the utilisation of surveillance systems and treatment facilities established during the COVID-19 pandemic. However, dengue incidence remains high, and other dengue control strategies-including the deployment of Wolbachia-infected mosquitoes-should be considered in Timor-Leste.

The first confirmed outbreak of chikungunya reported in Timor-Leste, 2024.

Abstract: Timor-Leste is a mountainous, half-island nation with a population of 1.3 million, which shares a land border with Indonesia and is 550 km from Darwin, Australia. Since independence in 2002, Timor-Leste has achieved significant development; however, high levels of poverty remain. Chikungunya virus (CHIKV) is endemic in over 100 countries in Africa, Asia, Europe and in the Americas. It is transmitted by the bite of infected Aedes aegypti or Ae. albopictus mosquitoes, which are present in Timor-Leste and which contribute to annual rainy-season dengue virus (DENV) outbreaks. Symptomatic people typically suffer from acute onset of fever, usually accompanied by severe arthritis or arthralgia. Joint pain can be debilitating for several days, and may sometimes last for weeks, months or years. Unlike DENV infection which has significant mortality, most people recover completely. Between 2002 and 2023, there were 26 cases of CHIKV notified in Australia who acquired their infection in Timor-Leste; however, laboratory testing capability for CHIKV in Timor-Leste only became available in 2021 using polymerase chain reaction (PCR). The first locally diagnosed case was notified in November 2023. In January 2024, an outbreak of CHIKV was recognised in Timor-Leste for the first time, with 195 outbreak cases reported during 1-31 January 2024; all were PCR positive. There were no cases hospitalised, and no deaths. The median age of cases was 17 years (range 1-76 years); 51% were males. Cases were reported across the country; most (88/195) were from Dili, although the highest incidence was seen in the neighbouring municipality of Ermera (monthly incidence rate of 58.8 cases per 100,000 population). This first reported outbreak of CHIKV in Timor-Leste highlights the need for improved mosquito-borne illness control and response strategies, including minimising breeding sites and promoting early presentation for treatment and differential diagnosis from DENV, and consideration of the deployment of Wolbachia-infected mosquitoes, particularly as they have shown to reduce the transmission of CHIKV, DENV and Zika virus, all of which pose threats in Timor-Leste.

Vaccine Preventable Disease Seroprevalence in a Nationwide Assessment of Timor-Leste (VASINA-TL): study protocol for a population-representative cross-sectional serosurvey.

INTRODUCTION: Historic disruption in health infrastructure combined with data from a recent vaccine coverage survey suggests there are likely significant immunity gaps to vaccine preventable diseases and high risk of outbreaks in Timor-Leste. Community-based serological surveillance is an important tool to augment understanding of population-level immunity achieved through vaccine coverage and/or derived from prior infection. METHODS AND ANALYSIS: This national population-representative serosurvey will take a three-stage cluster sample and aims to include 5600 individuals above 1 year of age. Serum samples will be collected by phlebotomy and analysed for measles IgG, rubella IgG, SARS-CoV-2 antispike protein IgG, hepatitis B surface antibody and hepatitis B core antigen using commercially available chemiluminescent immunoassays or ELISA. In addition to crude prevalence estimates and to account for differences in Timor-Leste's age structure, stratified age-standardised prevalence estimates will be calculated, using Asia in 2013 as the standard population. Additionally, this survey will derive a national asset of serum and dried blood spot samples which can be used for further investigation of infectious disease seroepidemiology and/or validation of existing and novel serological assays for infectious diseases. ETHICS AND DISSEMINATION: Ethical approval has been obtained from the Research Ethics and Technical Committee of the Instituto Nacional da Saúde, Timor-Leste and the Human Research Ethics Committee of the Northern Territory Department of Health and Menzies School of Health Research, Australia. Co-designing this study with Timor-Leste's Ministry-of-Health and other relevant partner organisations will allow immediate translation of findings into public health policy, which may include changes to routine immunisation service delivery and/or plans for supplementary immunisation activities.

The COVID-19 laboratory response in Timor-Leste; a story of collaboration.

Timor-Leste is a small nation of 1.3 million people which shares a land border with Indonesia and is 550 km from Darwin, Australia. It is one of the poorest nations in Asia. The National Health Laboratory (NHL) and its network of smaller laboratories in Timor-Leste had limited capacity to perform molecular diagnostic testing before the coronavirus disease 2019 (COVID-19) pandemic began. With the support of international development partners, the NHL rapidly expanded its molecular testing service. From March 2020 to February 2022, over 200,000 molecular tests were performed; COVID-19 testing sites were established in hospital and community health center laboratories and all 13 municipalities, and the number of scientists and technicians at the molecular diagnostic laboratory at the NHL increased from five to 28 between 2019 and 2022. Molecular diagnostic testing for COVID-19 was successfully established at the NHL and in the municipalities. The molecular diagnostic laboratory at NHL is now equipped to respond to not only large-scale COVID-19 testing but also laboratory detection of other infectious diseases, preparing Timor-Leste for future outbreaks or pandemics.

The epidemiology of the COVID-19 pandemic in the small, low-resource country of Timor-Leste, January 2020 - June 2022.

Abstract: Timor-Leste, a small, mountainous half-island nation which shares a land border with Indonesia and which is 550 km from Australia, has a population of 1.3 million and achieved independence for the second time in 2002. It is one of the poorest nations in Asia. In response to the global coronavirus disease 2019 (COVID-19) pandemic, the Timor-Leste Ministry of Health undertook surveillance and contact tracing activities on all notified COVID-19 cases. Between 1 January 2020 and 30 June 2022, there were 22,957 cases of COVID-19 notified which occurred in three waves, the first which was delayed until April 2021 (community transmission of B.1.466.2 variant following major flooding), followed by waves in August 2021 (B.1.617.2 Delta variant transmission) and February 2022 (B.1.1.529 Omicron variant transmission). There were 753 people hospitalised due to COVID-19 and 133 deaths. Of the 133 deaths, 122 (92%) were considered not fully vaccinated (< 2 COVID-19 vaccines) and none had received boosters. Timor-Leste implemented measures to control COVID-19, including: rapid closure of international borders; isolation of cases; quarantining of international arrivals and close contacts; restrictions on internal travel; social and physical distancing; and, finally, a country-wide vaccination program. The health system's capacity was never exceeded.