Human coronavirus infections in rural Thailand: a comprehensive study using real-time reverse-transcription polymerase chain reaction assays

Abstract

Background: We sought to determine whether infections with human coronaviruses (HCoVs) 229E, OC43, HKU1, and NL63 are associated with pneumonia and to define the epidemiology of HCoV infection in rural Thailand.

Methods: We developed a real-time reverse-transcription polymerase chain reaction (RT-PCR) assay panel for the recognized HCoV types and compared HCoV infections in patients hospitalized with pneumonia, outpatients with influenza-like illness, and asymptomatic control patients between September 2003 and August 2005.

Results: During study year 1, 43 (5.9%) of 734 patients with pneumonia had HCoV infections; 72.1% of the infections were with OC43. During study year 2, when control patients were available, 21 (1.8%) of 1156 patients with pneumonia, 12 (2.3%) of 513 outpatients, and 6 (2.1%) of 281 control patients had HCoV infections. Compared with infection in control patients, infection with any HCoV type or with all types combined was not associated with pneumonia (adjusted odds ratio for all HCoV types, 0.67 [95% confidence interval, 0.26-1.75]; P=.40). HCoV infections were detected throughout both study years; 93.6% of OC43 infections in the first year occurred from January through March.

Conclusions: HCoV infections were infrequently detected in rural Thailand by use of sensitive real-time RT-PCR assays. We found no association between HCoV infection and illness. However, we noted year-to-year variation in the prevalence of HCoV strains, which likely influenced our results.

Table 1.

Human coronavirus real-time reverse-transcription polymerase chain reaction (RT-PCR) panel primer and probe sequences.

Table 2.

Human coronavirus (HCoV) infections among patients hospitalized with pneumonia during 2 years of surveillance, Sa Kaeo Province, Thailand, 1 September 2003 to 31 August 2005.

Table 3.

Human coronavirus (HCoV) testing results for outpatients with influenza-like illness and control patients (persons without respiratory tract symptoms, fever, or diarrhea during the previous 3 days) in study year 2 (1 September 2004 to 31 August 2005).

Table 4.

Coinfections of respiratory specimens with human coronavirus (HCoV) and another respiratory virus during the 2-year study, 1 September 2003 to 31 August 2005.

Figure 1.

Seasonality of human coronavirus (HCoV) infections during 2 years of surveillance, Sa Kaeo Province, Thailand, 1 September 2003 to 31 August 2005. The first year includes HCoV infections in hospitalized patients with pneumonia, and the second year includes HCoV infections in pneumonia patients, outpatients with influenza-like illness, and control patients.