Prevalence and prediction of Lyme disease in Hainan province.

Lin Zhang,Xuexia Hou,Guangqing Miao,Xiaoying Fu,Sha Li,Xiaona Yang,Qin Hao,Ting Chen,Huan Li,Xiong Zhu,Peter J Krause

doi:10.1371/journal.pntd.0009158

Abstract

Lyme disease (LD) is one of the most important vector-borne diseases worldwide. However, there is limited information on the prevalence and risk analysis using correlated factors in the tropical areas. A total of 1583 serum samples, collected from five hospitals of Hainan Province, were tested by immunofluorescence assay (IFA) and western blot (WB) analyses using anti-Borrelia burgdorferi antibodies. Then, we mapped the distribution of positive rate (by IFA) and the spread of confirmed Lyme patients (by WB). Using ArcGIS, we compiled host-vector-human interactions and correlated data as risk factor layers to predict LD risk in Hainan Province. There are three LD hotspots, designated hotspot I, which is located in central Hainan, hotspot II, which contains Sanya district, and hotspot III, which lies in the Haikou-Qiongshan area. The positive rate (16.67% by IFA) of LD in Qiongzhong, located in hotspot I, was higher than that in four other areas. Of confirmed cases of LD, 80.77% of patients (42/52) whose results had been confirmed by WB were in hotspots I and III. Hotspot II, with unknowed prevalence of LD, need to be paid more attention considering human-vector interaction. Wuzhi and Limu mountains might be the most important areas for the prevalence of LD, as the severe host-vector and human-vector interactions lead to a potential origin site for LD. Qiongzhong is the riskiest area and is located to the east of Wuzhi Mountain. In the Sanya and Haikou-Qiongshan area, intervening in the human-vector interaction would help control the prevalence of LD.

Highlights

Lyme disease (LD) is caused by the tick-borne spirochete Borrelia burgdorferi, and has been reported to be widely distributed across China mainland[1,2]
A total of 1583 serum samples obtained from patients with arthritis or neurological symptoms were examined for B. burgdorferi using the two-step test
A total of 94 serum samples were found to be positive by immunofluorescence assay (IFA) (IFA titer, 128 for IgG and 64 for IgM); an overall infection rate of all five hospitals in Hainan Province was 5.94%

Summary

Introduction

Lyme disease (LD) is caused by the tick-borne spirochete Borrelia burgdorferi, and has been reported to be widely distributed across China mainland[1,2]. Human LD generally occurs in stages, from the early localized stage of erythema migrans, fatigue, chills, and fever, to a late disseminated stage of intermittent bouts of arthritis with severe joint pain and swelling and neurological symptoms [3,4]. While culture of B. burgdorferi from patient specimens is difficult and single serological tests are partially hampered by the disease stage at which antibodies start to appear, leading to insufficient results; patients may still be seronegative in the early stages of infection[4,5]. In China, without surveillance, Lyme patients often don’t find themselves ill until late symptoms occur. The US-CDC diagnosed LD by serological tests in a two-step process, including a screening test (enzyme immunoassay (EIA) or immunofluorescence assay (IFA)) and confirmation test (western blotting, WB)[4]

Methods

Results

Discussion

Conclusion