Massive Tick Bites Causing Spotted Fever Rickettsial Infection: A Hazard in a Tea Plantation, Sri Lanka

Tea plantations in Sri Lanka cover the central hills of the island, where spotted fever group (SFG) rickettsial infection is common. In most cases, the history of tick bite is obscure and eschars are not present. A 45-y-old female experienced massive tick bites while working in her tea plantation. She developed fever 2 d after exposure, but the diagnosis of SFG infection was not considered until a skin rash appeared on the eighth day. She had a very high titer of antirickettsial antibodies detected by immunofluorescence assay and responded to doxycycline. Here, we highlight the high risk of exposure to ticks and tick bites within tea estates and its causal relationship to SFG infection, which is increasing in Sri Lanka. Active case detection, notification, surveillance, and community awareness are imperative. Possible preventative measures for tick bites have to be introduced. There is a need to explore the effectiveness of local remedies currently in use.

First glimpse into the origin and spread of the Asian longhorned tick, Haemaphysalis longicornis, in the United States

Established populations of Asian longhorned ticks (ALT), Haemaphysalis longicornis, were first identified in the United States (US) in 2017 by sequencing the mitochondrial cytochrome c oxidase subunit I (cox1) 'barcoding' locus followed by morphological confirmation. Subsequent investigations detected ALT infestations in 12, mostly eastern, US states. To gain information on the origin and spread of US ALT, we (1) sequenced cox1 from ALT populations across 9 US states and (2) obtained cox1 sequences from potential source populations [China, Japan and Republic of Korea (ROK) as well as Australia, New Zealand and the Kingdom of Tonga (KOT)] both by sequencing and by downloading publicly available sequences in NCBI GenBank. Additionally, we conducted epidemiological investigations of properties near its initial detection locale in Hunterdon County, NJ, as well as a broader risk analysis for importation of ectoparasites into the area. In eastern Asian populations (China/Japan/ROK), we detected 35 cox1 haplotypes that neatly clustered into two clades with known bisexual versus parthenogenetic phenotypes. In Australia/New Zealand/KOT, we detected 10 cox1 haplotypes all falling within the parthenogenetic cluster. In the United States, we detected three differentially distributed cox1 haplotypes from the parthenogenetic cluster, supporting phenotypic evidence that US ALT are parthenogenetic. While none of the source populations examined had all three US cox1 haplotypes, a phylogeographic network analysis supports a northeast Asian source for the US populations. Within the United States, epidemiological investigations indicate ALT can be moved long distances by human transport of animals, such as horses and dogs, with smaller scale movements on wildlife. These results have relevant implications for efforts aimed at minimizing the spread of ALT in the United States and preventing additional exotic tick introductions.

Revisiting detachment techniques in human-biting ticks

BACKGROUND

Early and complete removal of ticks using the right technique is important to reduce tick-transmitted diseases. Several chemical and mechanical detachment techniques have been described previously.

OBJECTIVE

We aimed to compare the performance of 4 tick-detachment techniques that are widely used in human beings and to determine the optimal method from these techniques.

METHODS

A cross-sectional study was conducted on 160 patients between April and June 2010. Patients with reported tick bite were reviewed retrospectively and divided into the following 4 groups according to the tick-detachment technique used: card detachment, lassoing, freezing, and tweezers. Performance of each technique was evaluated according to the number of fully detached, nondetached, and crushed ticks and the duration of application.

RESULTS

Of the 160 tick-bite cases assessed, we found the following efficacy rates: 82.5% (33/40), technique using tweezers; 47.5% (19/40), lassoing technique; 7.5% (3/40), card detachment; and 0% (0/40), freezing technique. The efficacy rate of the technique using tweezers was significantly higher than that of the other 3 techniques (P < .05).

LIMITATIONS

This was a relatively small sample size and not designed as a randomized clinical trial.

CONCLUSION

Tick detachment using tweezers, performed in an appropriate manner, is the easiest and most effective technique.