Outcome of Three Commercial Serum ELISAs and Faecal Detection of Mycobacterium avium subsp. paratuberculosis in Consecutive Samples from a Cattle Herd with Low Prevalence of Paratuberculosis (Johne’s Disease)

Paratuberculosis (Johne’s disease) in ruminants is caused by Mycobacterium avium subsp. paratuberculosis (MAP). Owing to the lack of accurate laboratory tests, diagnosis is challenging in subclinically infected cattle. To evaluate the long‐term performance of serum ELISAs for the detection of paratuberculosis in a dairy herd with low MAP‐prevalence, three investigations of all the cows and the consecutive testing of 33 cows suspected to be infected with MAP and 30 cows classified as MAP free were performed over a period of 22 months. Blood samples were tested by three commercial serum ELISAs, MAP shedding was detected by bacteriological culture and polymerase chain reaction (PCR). The ELISA results varied in a wide range in the herd investigations with 1.2% to 18.8% positive samples, the faecal samples were positive for MAP between 1.8% and 4.9% in the three herd investigations. Over the study period, ELISA‐positive serum samples varied between 0.0% and 69.7% in MAP‐suspicious and 0.0% and 17.6% in MAP‐unsuspicious cows with a poor correlation between ELISAs and faecal shedding. The correlation coefficient of the optical density values of the three ELISAs varied between 0.348 and 0.61. Evidence of cow specific variations of residuals was found in all linear models. The linear mixed models showed relevant contribution of cow specific variation in explanation of the residual variances. They also showed significant effects of the explanatory ELISA, the group (MAP‐suspicious or MAP‐unsuspicious) and the time of sampling. It can be concluded that the choice of the laboratory test significantly influences the outcome of the testing for MAP and that none of the three ELISAs can be thoroughly recommended as single test for the early diagnosis of paratuberculosis in cattle. Test results should always be interpreted with caution to avoid erroneous decisions and the disappointment of those engaged in the abatement of paratuberculosis.     

Factors associated with viral non-suppression among adolescents living with HIV in Cambodia: a cross-sectional study

Background

Adolescents living with HIV on antiretroviral therapy (ART) have worse treatment adherence, viral suppression, and mortality rates compared to adults. This study investigated factors associated with viral non-suppression among adolescents living with HIV in Cambodia.

Methods

A cross-sectional study was conducted in August 2016 among 328 adolescents living with HIV aged 15–17 years who were randomly selected from 11 ART clinics in the capital city of Phnom Penh and 10 other provinces. Clinical and immunological data, including CD4 count and viral load, were obtained from medical records at ART clinics. Adolescents were categorized as having achieved viral suppression if their latest viral load count was <?1000 ribonucleic acid (RNA) copies/mL. Multivariate logistic regression analysis was performed to identify factors independently associated with viral non-suppression.

Results

The mean age of the participants was 15.9 years (SD?=?0.8), and 48.5% were female. Median duration on ART was 8.6 (interquartile range?=?6.0–10.6) years. Of total, 76.8% of the participants had achieved viral suppression. After adjustment for other covariates, the likelihood of having viral non-suppression remained significantly lower among adolescents who were: older/aged 17 (AOR?=?0.46, 95% CI 0.21–0.98), had been on ART for more than 9 years (AOR?=?0.35, 95% CI 0.19–0.64), had most recent CD4 count of >?672 (AOR?=?0.47, 95% CI 0.26–0.86), had a relative as the main daily caregiver (AOR?=?0.37, 95% CI 0.17–0.80), and did not believe that there is a cure for AIDS (AOR?=?0.40, 95% CI 0.21–0.75) compared to their reference group. The likelihood of having viral non-suppression also remained significantly higher among adolescents who had first viral load >?628 RNA copies/mL (AOR?=?1.81, 95% CI 1.05–4.08) and among those who were receiving HIV care and treatment from an adult clinic (AOR?=?2.95, 95% CI 1.56–5.59).

Conclusions

The proportion of adolescents living with HIV with viral suppression in this study was relatively high at 76.8%, but falls short of the global target of 90%. Programs targeting younger adolescents and adolescents in transition from pediatric to adult care with a range of interventions including psychosocial support and treatment literacy could further improve viral suppression outcomes.