Tonga Measles Outbreak 2019 - Situation Report #3
1. Summary of Situation
An outbreak of measles has occurred following the return of a squad of Tongan rugby players from New Zealand where one player developed measles. Twelve other players were in the incubation period of the illness during travel back to Tonga and developed symptoms on 6th- 9th October. The diagnosis was laboratory confirmed for 6 players tested. Boys in the touring squad came from the following schools and locations: Tonga College 'Atele (TCA), Tupou College Toloa (TCT) (a boarding school), Tonga High School (THS) and a small number from other schools on Tongatapu and the islands of Vava'u, Ha'apai and 'Eua.
The outbreak has involved students (mainly) from schools on Tongatapu as well as students from Vava'u High School. There is currently no evidence to suggest that new lines of transmission have occurred. Cases are epidemiologically linked to the initial imported cases.
The Ministry of Health Epidemic Task Force has been convened comprising public health, clinician and laboratory representatives to advice on the management of the outbreak.
Note: Refer to earlier SITREPS for further detail of the initial cases and response.
2. Current Situation
As at 28th October, 107 cases of confirmed or suspected measles have been identified in Tonga. Clinicians have reported that cases are generally experiencing a mild illness.
The attached charts outline the results of analysis of current case information. The epidemic curve presents a picture of a propagated outbreak matching the incubation period for measles. It is too early to say if the curve shows evidence of outbreak control. Teenage males predominate as cases, consistent with the likely transmission of disease through the boy's schools. Three of 5 cases in females have been in the 15-19 age group, another less than 6 months of age and another 23 years old. Predominate symptoms include rash (96% of cases) and fever (76% of cases).
Two cases have been admitted to Vaiola Hospital and one admitted in Prince Ngu hospital, Vava'u. All admitted cases have recovered well or are recovering well. No serious cases of disease or deaths have been reported form the outbreak. No cases of measles have been reported amongst health care staff.
Key events/ issues since last SITREP
Further laboratory testing at LabPlus in Auckland of samples from the rugby squad has found that of 6 players testing positive to PCR, all demonstrated IgG+/IgM- results on serology testing. This is indicative of waning immunity with the infections breaking through the existing protective antibodies. With some of the boys having a two-dose vaccination history with MR vaccine, this is a concerning development. Samples will be forwarded to VIDRL for further testing.
An outbreak linked to members of the touring rugby squad has occurred in Vava;u. As at 28/10/2019 a total of 12 cases (two rugby players and 10 contacts) have been identified in Vava'u. Details of these cases are not shown in the charts below since an internet outage prevented the transfer of information on the cases. (See below for further actions)
The IHR National Focal Point (NFP) for Tonga (Dr Siale) received notification of a player (20 y/o male) in a Tongan Futsal team who was diagnosed with measles after arriving in NZ on 14th October. It is believed he contracted the illness in Tonga. Symptoms began on 18th October and a rash appeared on 20th October. A sample taken on 22nd October for PCR was positive. The rest of the squad flew to New Caledonia. The NFP in New Caledonia was contacted by NZ NFP. It is unclear what measures were taken with the squad prior to leaving NZ.