Epidemiologic studies on human enteric viruses in Cameroon

Enteric viruses are a diverse group of viruses that include those that multiply in the intestinal epithelium and cause gastroenteritis, and those that first multiply in the intestine and then spread to extra-intestinal target organs where they cause other diseases. Noroviruses and enteroviruses fall within the former and the latter category respectively. Noroviruses are considered to be the most common cause of acute non-bacterial gastroenteritis in both children and adults in industrialized countries. Enteroviruses may induce diseases of varying severity ranging from conjunctivitis, acute flaccid paralysis, encephalitis, aseptic meningitis, and hand, foot and mouth disease. The risk of infection by enteric viruses is higher in sub-Saharan Africa compared to developed countries probably due to sub-optimal sanitation and hygienic conditions as well as to low quality of drinking water especially in rural areas. In Cameroon, very limited studies have been carried out on the epidemiology of these viruses. Globally, comprehensive prospective data on the dynamics of circulation of noro- and enteroviruses are scarce. There are no vaccines or therapeutics for norovirus infections, therefore advanced knowledge of the epidemiology is necessary for adequate prevention and control of the disease. Both viruses are transmitted by the fecal-oral-route, and an important feature of these viruses is the silent shedding in asymptomatic persons which may facilitate the transmission to susceptible persons. This thesis is focused on the seasonality, genetic diversity and dynamics of circulation of noro- and enteroviruses in Cameroon. Fecal samples were collected from participants and enteric viruses were detected by an in-house multiplex real-time PCR assay. Norovirus genotyping was achieved by RdRp-N/S genomic region sequencing, while enterovirus identification and typing was done by amplification of the 5’UTR-VP4 and partial VP1 regions of the genome respectively. To investigate the sequence diversity and strain circulation, all the sequences were subjected to phylogenetic analysis. A high prevalence and diversity of enteric viruses among children and adults was observed which was associated with a high frequency of infections with different strains. Up to five different enteric viruses were detected in a healthy child at a single observation. In a longitudinal follow-up, 1-5 (mean 2.0) different enterovirus infections occurred in children within a year. The study reveals the first description of norovirus in Cameroon and the discovery of a novel enterovirus type designated EV-A119. There was no statistical difference in the detection of norovirus in persons with diarrhea and in those without diarrhea suggesting that, although noroviruses are highly prevalent, they may not be a major cause of diarrhea in the study population. The observed shift in the predominant enterovirus species or norovirus genogroup from one period to the other, and prolonged viral excretion of up to 10 months for enterovirus in asymptomatic persons has great public health implications in the control of diseases caused by these viruses. This study also revealed a strong association between rainfall and the prevalence of noro- and enteroviruses. Taken together, the high degree of circulation of diverse noro- and enteroviruses in a healthy population in Cameroon suggests silent shedding of these viruses into the environment and eventual contamination of sources for drinking water. These naturally circulating noro- and enteroviruses may induce strong innate and adaptive immune responses and raise question whether these viruses may constitute components of the intestinal ‘virobiota’. Conversely, the detection of naturally circulating rotaviruses was low. This may explain why rotavirus detection in feces has been strongly associated with diarrheal disease. The obtained insights into the dynamics of circulation of these viruses can hopefully be used to develop adequate preventive and control strategies in order to eliminate symptomatic infections caused by these viruses

The threat of antimicrobial resistance in developing countries: causes and control strategies

Abstract The causes of antimicrobial resistance (AMR) in developing countries are complex and may be rooted in practices of health care professionals and patients’ behavior towards the use of antimicrobials as well as supply chains of antimicrobials in the population. Some of these factors may include inappropriate prescription practices, inadequate patient education, limited diagnostic facilities, unauthorized sale of antimicrobials, lack of appropriate functioning drug regulatory mechanisms, and non-human use of antimicrobials such as in animal production. Considering that these factors in developing countries may vary from those in developed countries, intervention efforts in developing countries need to address the context and focus on the root causes specific to this part of the world. Here, we describe these health-seeking behaviors that lead to the threat of AMR and healthcare practices that drive the development of AMR in developing countries and we discuss alternatives for disease prevention as well as other treatment options worth exploring

Point-of-care diagnosis and risk factors of infantile, rotavirus-associated diarrhoea in Calabar, Nigeria

Background: Rotaviruses are the primary cause of acute gastroenteritis in young children worldwide and a significant proportion of these infections occur in Africa. Objectives: In the present study, we determined the prevalence and risk factors of rotavirus infection among children younger than age 5 years with or without diarrhoea in Calabar, Nigeria, using a rapid point-of-care test. Methods: Two hundred infants younger than age 5 years presenting with acute gastroenteritis and a control group of 200 infants without diarrhoea were tested for rotavirus. Each stool sample was homogenised in an extraction buffer and the supernatant added into the sample well of the Rida Quick rotavirus test cassette and allowed to run for 5 minutes at room temperature. When both the control band and test band were visible on the test cassette a positive result was recorded, whereas when only the control band was visible a negative results was recorded. Results: Rotavirus was detected in 25 (12.5%) of children with diarrhoea and in no children without diarrhoea. Our results demonstrated that children who were exclusively breast-fed by their mothers were not infected with rotavirus and that 92% of the infants infected with rotavirus experienced vomiting. Conclusion: These data demonstrate that asymptomatic rotavirus infection is rare and that rotavirus is commonly detected in stool samples of children suffering from diarrhoea with concomitant vomiting. Use of point-of-care rotavirus tests will enhance early diagnosis of rotavirus-associated diarrhoea and reduce irrational use of antibiotics

Coronavirus surveillance in wildlife from two Congo basin countries detects RNA of multiple species circulating in bats and rodents.

Coronaviruses play an important role as pathogens of humans and animals, and the emergence of epidemics like SARS, MERS and COVID-19 is closely linked to zoonotic transmission events primarily from wild animals. Bats have been found to be an important source of coronaviruses with some of them having the potential to infect humans, with other animals serving as intermediate or alternate hosts or reservoirs. Host diversity may be an important contributor to viral diversity and thus the potential for zoonotic events. To date, limited research has been done in Africa on this topic, in particular in the Congo Basin despite frequent contact between humans and wildlife in this region. We sampled and, using consensus coronavirus PCR-primers, tested 3,561 wild animals for coronavirus RNA. The focus was on bats (38%), rodents (38%), and primates (23%) that posed an elevated risk for contact with people, and we found coronavirus RNA in 121 animals, of which all but two were bats. Depending on the taxonomic family, bats were significantly more likely to be coronavirus RNA-positive when sampled either in the wet (Pteropodidae and Rhinolophidae) or dry season (Hipposideridae, Miniopteridae, Molossidae, and Vespertilionidae). The detected RNA sequences correspond to 15 alpha- and 6 betacoronaviruses, with some of them being very similar (>95% nucleotide identities) to known coronaviruses and others being more unique and potentially representing novel viruses. In seven of the bats, we detected RNA most closely related to sequences of the human common cold coronaviruses 229E or NL63 (>80% nucleotide identities). The findings highlight the potential for coronavirus spillover, especially in regions with a high diversity of bats and close human contact, and reinforces the need for ongoing surveillance