Association of the CT values of real-time PCR of viral upper respiratory tract infection with clinical severity, Kenya

Quantitative real-time polymerase chain reaction (qRT-PCR) assay of the upper respiratory tract is used increasingly to diagnose lower respiratory tract infections. The cycle threshold (CT ) values of qRT-PCR are continuous, semi-quantitative measurements of viral load, although interpretation of diagnostic qRT-PCR results are often categorized as positive, indeterminate, or negative, obscuring potentially useful clinical interpretation of CT values. From 2008 to 2010, naso/oropharyngeal swabs were collected from outpatients with influenza-like illness, inpatients with severe respiratory illness, and asymptomatic controls in rural Kenya. CT values of positive specimens (i.e., CT values < 40.0) were compared by clinical severity category for five viruses using Mann-Whitney U-test and logistic regression. Among children <5 years old we tested with respiratory syncytial virus (RSV), inpatients had lower median CT values (27.2) than controls (35.8, P = 0.008) and outpatients (34.7, P < 0.001). Among children and older patients infected with influenza virus, outpatients had the lowest median CT values (29.8 and 24.1, respectively) compared with controls (P = 0.193 for children, P < 0.001 for older participants) and inpatients (P = 0.009 for children, P < 0.001 for older participants). All differences remained significant in logistic regression when controlling for age, days since onset, and coinfection. CT values were similar for adenovirus, human metapneumovirus, and parainfluenza virus in all severity groups. In conclusion, the CT values from the qRT-PCR of upper respiratory tract specimens were associated with clinical severity for some respiratory viruses.

Risk factors for hospitalized seasonal influenza in rural western Kenya

Background

Risk factors for influenza hospitalization in Africa are unknown, including the role of HIV.

Methods

We conducted a case-control study of risk factors for hospitalized seasonal influenza among persons in rural western Kenya, a high HIV prevalence area, from March 2006- August 2008. Eligible cases were ≥five years old, admitted to health facilities with respiratory symptoms, and had nasopharyngeal/oropharyngeal swab specimens that tested positive for influenza A or B by real-time reverse transcription-PCR. Three randomly selected age-, sex- and neighborhood-matched controls were enrolled per case. A structured questionnaire was administered and home-based HIV testing was performed. Risk factors were evaluated using conditional logistic regression.

Results

A total of 64 cases (38 with influenza A and 26 with influenza B) and 190 controls were enrolled. The median age was 16 years (range 5–69 years). Among cases, 24.5% were HIV-infected versus 12.5% of controls (p = 0.004). Among persons ≥18 years old, 13 (59%) of 22 tested cases were HIV-positive compared with 15 (24%) of 62 tested controls (p = 0.005). In multivariable analysis, HIV-infection was associated with hospitalization due to influenza [adjusted Odds Ratio (aOR) 3.56, 95% CI 1.25–10.1]. The mean CD4 count among HIV-infected cases and controls was similar (399 vs. 387, respectively, p = 0.89). Chronic lung disease (aOR 6.83, 95% CI 1.37–34.0) was also associated with influenza hospitalization in multivariable analysis. Active pulmonary tuberculosis was associated with influenza hospitalization in bivariate, but not multivariable, analysis.

Conclusions

People with HIV infection and chronic lung disease were at increased risk of hospitalized influenza in rural Kenya. HIV infection is common in many parts of sub-Saharan Africa. Influenza vaccine might prevent severe influenza in these risk groups.

The population-based burden of influenza-associated hospitalization in rural western Kenya, 2007-2009

OBJECTIVE

To estimate the burden and age-specific rates of influenza-associated hospitalization in rural western Kenya.

METHODS

All 3924 patients with respiratory illness (defined as acute cough, difficulty in breathing or pleuritic chest pain) who were hospitalized between June 2007 and May 2009 in any inpatient health facility in the Kenyan district of Bondo were enrolled. Nasopharyngeal and oropharyngeal swabs were collected and tested for influenza viruses using real-time reverse transcriptase polymerase chain reaction (RT-PCR). In the calculation of annual rates, adjustments were made for enrolled patients who did not have swabs tested for influenza virus.

FINDINGS

Of the 2079 patients with tested swabs, infection with influenza virus was confirmed in 204 (10%); 176, 27 and 1 were found to be RT-PCR-positive for influenza A virus only, influenza B virus only, and both influenza A and B viruses, respectively. Among those tested for influenza virus, 6.8% of the children aged < 5 years and 14.0% of the patients aged ≥ 5 years were found positive. The case-fatality rate among admitted patients with PCR-confirmed infection with influenza virus was 2.0%. The annual rate of hospitalization (per 100,000 population) was 699.8 among patients with respiratory illness and 56.2 among patients with influenza (with 143.7, 18.8, 55.2, 65.1 and 57.3 hospitalized patients with influenza virus per 100,000 people aged < 5, 5-19, 20-34, 35-49 and ≥ 50 years, respectively).

CONCLUSION

In a rural district of western Kenya, the rate of influenza-associated hospitalization was highest among children aged less than 5 years.

Notes from the Field: Splenomegaly of Unknown Etiology in Congolese Refugees Applying for Resettlement to the United States - Uganda, 2015

Approximately 70,000-90,000 refugees are resettled to the United States each year, and during the next 5 years, 50,000 Congolese refugees are expected to arrive in the United States. The International Organization for Migration (IOM) performs refugee medical examinations overseas for the U.S. Refugee Resettlement Program. In 2014, IOM reported that a large number of U.S.-bound Congolese refugees from Uganda had spleens that were enlarged on examination. During two evaluations of refugee populations in western Uganda in March and July 2015, refugees with splenomegaly on physical examination were offered additional assessment and treatment, including abdominal ultrasonography and laboratory testing. Among 987 persons screened, 145 (14.7%) had splenomegaly and received further testing. Among the 145 patients with splenomegaly, 63.4% were aged 5-17 years (median = 14.8 years). There was some evidence of family clustering, with 33 (22.7%) of the 145 cases occurring in families.