Arboviral vaccines for use in pregnant travelers.

Pregnant women traveling abroad can be exposed to a variety of arboviruses, primarily spread by mosquitoes or ticks. Some arboviral infections can be of particular concern for pregnant women or their fetuses. Vaccination is one preventive measure that can reduce the risk for infection. Several arboviral vaccines have been licensed for many years and can be used to prevent infection in travelers, namely Japanese encephalitis, yellow fever, and tick-borne encephalitis vaccines. Recommendations on use of these vaccines in pregnancy vary. Other arboviral vaccines have been licensed but are not indicated for use in pregnant travelers (e.g., dengue vaccines) or are in development (e.g., chikungunya, Zika vaccines). This review describes arboviral vaccines for travelers, focusing on women who are pregnant and those planning travel during pregnancy.

An epidemic of dengue 3 in far north Queensland, 1997-1999.

OBJECTIVES: To describe an epidemic of dengue type 3 that occurred in far north Queensland in 1997-1999 and its influence on the further development of dengue prevention and control strategies. DESIGN: Epidemiological and laboratory investigation of cases, entomological surveys and phylogenetic analysis of dengue virus isolates. MAIN OUTCOME MEASURES: Numbers and characteristics of confirmed cases; Breteau Index (BI; number of containers breeding Aedes aegypti per 100 premises); effect of control measures on mosquito populations; genetic homology of epidemic virus with other dengue virus isolates. RESULTS: The epidemic lasted 70 weeks and comprised 498 confirmed cases in three towns (Cairns, Port Douglas and Mossman); 101 patients (20%) were admitted to hospital. Median interval between symptom onset and notification was seven days (range, 0-53 days), and cumulative duration of viraemia of public health significance was 2,072 days. BIs in affected areas were high, particularly in Mossman (45) and Port Douglas (31). Control measures significantly reduced mosquito populations (assessed as number of ovitraps containing Ae. aegypti eggs and mean number of eggs per trap [P< 0.05 for both]). However, transmission persisted in several foci, in part due to undetected waterfilled containers breeding Ae. aegypti. The epidemic virus belonged to serotype 3; phylogenetic analysis suggested it was imported from Thailand. CONCLUSIONS: The epidemic had greater morbidity than other recent Queensland epidemics of dengue and was harder to control, necessitating substantial revision of the Dengue Fever Management Plan for North Queensland. The epidemic's severity supports the hypothesis that dengue viruses from South East Asia are more virulent than others.

Recognising and responding to outbreaks of hepatitis A associated with child day-care centres.

OBJECTIVES: To assess the appropriateness of a protocol for recognising and responding to outbreaks of hepatitis A in child day-care centres and to determine if measles-mumps-rubella (MMR) vaccine was given too soon following the administration of normal human immunoglobulin (NIGH) to young children to control the outbreaks. DESIGN: Prospective surveillance to recognise cases of hepatitis A associated with, and outbreaks of hepatitis A in, day-care centres. MAIN OUTCOME MEASURES: The percentage of initial ('sentinel') cases of hepatitis A associated with day-care centres that were subsequently recognised as also being 'index' cases of outbreaks of hepatitis A in the centres, and the number of children 9-13 months of age when given NIGH who were subsequently given MMR less than three months later. RESULTS: Only 18 (16%) of the 114 sentinel day-care associated cases of hepatitis A were also index cases of outbreaks of hepatitis A in their respective centres. A total of 105 cases of hepatitis A were associated with the 18 outbreak centres; NIGH was administered to 928 (78%) of the attendee children, and to 105 (82%) of the susceptible staff, at the 18 centres. Three of the five children 9-13 months of age when given NIGH were given MMR less that three months later. CONCLUSIONS: Although outbreaks of hepatitis A were common events in day-care centres in north Queensland during the two-year study period, a single case of hepatitis A associated with a centre was a poor predictor of an outbreak within that centre. Precautions must be taken to ensure that live vaccines are not administered to young children too soon after NIGH.

Japanese encephalitis in north Queensland, Australia, 1998.

OBJECTIVE: To describe the circumstances of two cases of Japanese encephalitis (JE) in north Queensland in 1998, including one acquired on the Australian mainland. DESIGN: Serological surveillance of sentinel pigs for JE virus activity; serological surveys of humans and pigs and viral cultures of mosquito collections. SETTING: Islands in the Torres Strait and communities in the Northern Peninsula Area (NPA) and near the mouth of the Mitchell River in Cape York, Queensland, in the 1998 wet season (December 1997-May 1998). RESULTS: Sentinel pigs in the Torres Strait began to seroconvert to JE virus in February 1998, just before onset of JE in an unvaccinated 12-year-old boy on Badu island. By mid-April, most sentinel pigs had seroconverted. Numerous JE viruses were isolated from Culex annulirostris mosquitoes collected on Badu. In early March, a person working at the mouth of the Mitchell River developed JE. Serological surveys showed recent JE virus infection in 13 young pigs on a nearby farm, but not in 488 nearby residents. In NPA communities, sentinel pigs seroconverted slowly and JE viruses were isolated from three, but none of 604 residents showed evidence of recent infection. Nucleotide sequencing showed that 1998 JE virus isolates from the Torres Strait were virtually identical not only to the 1998 isolate from an NPA pig, but also to previous (1995) Badu isolates. CONCLUSIONS: JE virus activity was more widespread in north Queensland in the 1998 wet season than in the three previous wet seasons, but ecological circumstances (e.g., less intensive pig husbandry, fewer mosquitoes) appear to have limited transmission on the mainland. Nucleotide sequencing indicated a common source for the 1995 and 1998 JE viruses. Circumstantial evidence suggests that cyclonic winds carried infected mosquitoes from Papua New Guinea.