Human psittacosis: a review with emphasis on surveillance in Belgium.

Chlamydia psittaci causes psittacosis in humans, mainly in persons in contact with birds in either the setting of occupational or companion bird exposure. Infection is associated with a range of clinical manifestations from asymptomatic infection to severe atypical pneumonia and systemic disease. This paper reviews new knowledge on psittacosis, its legal and regulatory aspects and presents epidemiological data on psittacosis in Belgium. In Belgium, the number of reported positive laboratory results increased slowly since 2010, and in 2017, the number almost doubled compared to the two previous years. The number of psittacosis cases in Belgium, as in other countries, is probably highly underestimated, because of underdiagnoses and underreporting. Over the 3-year period, the mandatory notification system registered 24% only of all reported positive laboratory result. Therefore, increased awareness among general and occupational physicians, clinicians and the public is needed. Policies aimed at reducing psittacosis disease burden are justified, nevertheless national health authorities should provide more legal and financial support to implement more adequate C. psittaci diagnostic tools.

An unusual presentation of a case of human psittacosis.

BACKGROUND: Chlamydia psittaci is a gram-negative, obligate intracellular organism. Birds are the main reservoir, but also non-avian domestic animals and humans can be infected. In humans it mostly causes respiratory infections due to occupational exposure with varying severity. Sensitive and specific diagnostic tests are needed to define psittacosis in humans as these tests also allow rapid tracing of the animal source. However, diagnosis in humans is often based on time-consuming culture techniques and antibody detection assays as in many countries, the existing molecular diagnostic tests for psittacosis are not reimbursed by the public health insurance. CASE PRESENTATION: An 82-year old female was referred to the hospital with a non-productive cough since four weeks and since one week fever up to 39 °C, myalgia, generalized skin rash, acral edema and generalized weakness under treatment with moxifloxacin. Blood analysis showed signs of inflammation with mild eosinophilia. Chest CT showed multiple peripheral ground glass opacities with consolidation in both lungs. Pulmonary function testing only showed a mild decrease in diffusion capacity. Viral and bacterial serology were negative. As the patient kept a pet parakeet for over ten years, a nested PCR for C. psittaci was performed on a nasopharyngeal swab of the patient and on feces of the parakeet. Both returned positive for the same genotype. Genotyping was performed by a genotype-specific real-time PCR. The patient fully recovered after a ten-day course of azithromycin. CONCLUSION: Due to non-specific signs during psittacosis, early detection of the infection and differentiation from hypersensitivity pneumonitis can be challenging. Culture and antibody titers for C. psittaci have a lower sensitivity than PCR-testing due to several factors. We present a case of human psittacosis (presenting as pneumonia) with diagnosis based on clinical findings confirmed by means of nested PCR. This case suggests the added value of PCR in suspect cases despite negative serology. Our current paper underlines the need for a broader implementation of PCR for early diagnosis of human psittacosis and thus early initiation of correct antibiotic treatment with reduction of morbidity and mortality.

Altered expression of maize PLASTOCHRON1 enhances biomass and seed yield by extending cell division duration.

Maize is the highest yielding cereal crop grown worldwide for grain or silage. Here, we show that modulating the expression of the maize PLASTOCHRON1 (ZmPLA1) gene, encoding a cytochrome P450 (CYP78A1), results in increased organ growth, seedling vigour, stover biomass and seed yield. The engineered trait is robust as it improves yield in an inbred as well as in a panel of hybrids, at several locations and over multiple seasons in the field. Transcriptome studies, hormone measurements and the expression of the auxin responsive DR5rev:mRFPer marker suggest that PLA1 may function through an increase in auxin. Detailed analysis of growth over time demonstrates that PLA1 stimulates the duration of leaf elongation by maintaining dividing cells in a proliferative, undifferentiated state for a longer period of time. The prolonged duration of growth also compensates for growth rate reduction caused by abiotic stresses.