Zoonotic infections in Nigeria: overview from a medical perspective

Combatting anthrax outbreaks across Nigeria's national land borders: need to optimize surveillance with epidemiological surveys

BACKGROUND

Anthrax is a non-contagious zoonotic disease caused by the Gram-positive, spore-forming bacterium Bacillus anthracis. Infection is common in livestock and wild animals such as cattle, goats, sheep, camels, and antelopes. In humans, anthrax may occur after contact with contaminated carcasses or animal products like milk and meat. The best method to prevent anthrax in people is to ensure livestock are vaccinated, which significantly limits the risk of zoonotic spread to humans. However, the rate of vaccination of domesticated animals kept by nomadic pastoralists in West Africa is low. These groups regularly cross over national boundaries with their grazing herds. Nigeria is a country that historically has done comparatively well to contain this public health threat. However, in 2023 several outbreaks of human disease appear linked to the consumption of anthrax-contaminated animal products brought into Nigeria by pastoralists from neighboring countries. Clinical manifestations include skin sores or ulcers, nausea, vomiting, and fever. This article aims to raise awareness of recent outbreaks of anthrax in West Africa and to call for a renewed focus on measures to combat this neglected public health concern to the region.

MAIN BODY

The imperative to pinpoint pivotal issues relating to the ongoing emergence of anthrax cases in Nigeria cannot be overstated. By delving into the prevalence of anthrax in both livestock and human populations residing along Nigeria's borders, unraveling the genetic diversity and potential sources of B. anthracis strains, and identifying the primary animal host(s) responsible for transmission, we stand to enhance our understanding of this critical issue. Furthermore, investigating the multifaceted factors contributing to anthrax transmission, assessing community knowledge and practices, mapping common migratory routes of pastoralists, and formulating targeted intervention strategies tailored to the challenges of border communities, are each crucial steps towards effective control and prevention.

CONCLUSION

Closing these knowledge gaps on anthrax is not only essential for safeguarding both animal and human health but also for fostering sustainable and resilient communities. Addressing research questions on these interdisciplinary concerns will undoubtedly pave the way for informed decision-making, proactive measures, and a more secure future for Nigeria and its border regions.

Implementation of the Revised National Malaria Control Guidelines: Compliance and Challenges in Public Health Facilities in a Southern Nigerian State

Background

There has been a concerted effort to reduce malaria burden and bring malaria related mortality to zero. The objectives of this survey were to assess the level of adherence to the current revised malaria control guidelines in the public health facilities in Cross River State of Nigeria and to identify the challenges as well as suggest ways for improvement in treatment outcomes.

Methods

This was a mixed observational and qualitative survey conducted in 32 public health facilities from 21st to 25th June 2022. Treatment records on malaria were assessed for adherence to the National guidelines. In-depth interviews were conducted with 36 key informants and 4 purposefully selected stakeholders to identify the successes and challenges. Quantitative data were summarized and presented in simple proportions and percentages while qualitative information was recorded, the transcripts thematically coded, analyzed and presented using NVivo 11 software.

Results

The survey revealed that vector control program was poorly implemented across the state. For case management, presumptive treatment was frequently practiced especially at secondary health facilities for uncomplicated malaria. More than 60% of uncomplicated malaria were being treated with parenteral artemether instead of oral artemisinin combination therapy (ACTs) as recommended. Severe malaria were not treated with Intravenous (IV) Artesunate as first line drug in about 40% of the secondary health facilities. Key successes were noted in malaria management in pregnancy. Major challenges identified include: stock out of commodities, shortage of clinical man power, and low trust in parasitological diagnosis.

Conclusion

The survey showed that adherence to the key recommendations in various categories of malaria control among health care providers in the public health facilities was below expectation. Malaria preventive treatment in pregnancy with SP fared better perhaps because of its inclusion in ANC packages.

Emerging and re-emerging bacterial zoonoses in Nigeria: current preventive measures and future approaches to intervention

A characteristic of bacterial zoonoses, diseases caused by bacteria that can be transmitted to humans from animals, is a propensity to re-emerge. Several studies demonstrate their ongoing transmission in Nigeria, the most populous country in Africa. However, as local epidemiological data on bacterial zoonoses are inadequate the extent and impact of these infectious diseases is under-reported. Consequently, they are not a targeted priority of national public health policies. This limited recognition is despite indications of their possible roles in the widespread prevalence of non-malarial undifferentiated fever in Nigeria. While a number of animal reservoirs and arthropod vectors have been identified in the transmission routes of these diseases, an escalation of cases of undiagnosed febrile illness highlights the urgent need for a comprehensive assessment of other potential reservoirs, vectors and transmission cycles that may increase the local risk of infection with bacterial zoonoses. Animal health interventions have been proposed as a cost-effective strategy. Here, we present a broad overview of bacterial zoonotic infections of humans in Nigeria in the context of evolving epidemiological patterns. Further, we propose that facilitating the operation of a community-based One Health program is essential to providing the comprehensive epidemiological information that is required to improve prioritization of bacterial zoonoses. This would provide a driver for much needed investment in relevant public health interventions in Africa's most populous country.

Antibiotic Susceptibility Profiles of Campylobacter coli Isolated from Poultry Farms in Lagos Nigeria - A Pilot Study

Campylobacter jejuni and Campylobacter coli are among the leading causes of gastroenteritis in humans worldwide, particularly in Africa. Poultry remains a major source of Campylobacter species and a vector of transmission to humans.

This pilot study was aimed at isolating and determining the antibiotic susceptibility profiles of Campylobacter spp. from fresh poultry droppings collected from poultry farms in Lagos State, Nigeria. Susceptibility was assessed using the CLSI standards.

Standard microbiological methods were used in isolation, identification, and characterization of Campylobacter spp. Isolates were subjected to antibiotic susceptibility testing by the disk diffusion method.

Of the 150 poultry droppings analyzed, 8 (5.3%) harbored Campylobacterspp. All isolates proved to be C. coli since they were all negative for the hip gene. A percentage of 100% showed resistance to nalidixic acid, chloramphenicol, cloxacillin, and streptomycin. While 87.5% were susceptible to amoxicillin and amoxicillin/clavulanic acid, 62.5% were susceptible to tetracycline. Surprisingly, 62.5% of C. coli had decreased (intermediate) susceptibility to erythromycin.

Although there was a low prevalence of C. coli from poultry in this study, the presence of antibiotic resistant strains circulating the food chain could result in treatment failures and difficulty in case management if involved in infections of humans.

Neglected zoonotic diseases in Nigeria: role of the public health veterinarian

Zoonotic diseases accounts for about 75% of emerging infectious disease and can be devastating to both human and animal health globally. A subset of zoonotic diseases is referred to as "neglected zoonotic diseases - NZDs" as they mainly affect poor populations who live in close proximity to domestic or wild animals often in areas where access to health and adequate sanitary facilities are not available. Furthermore, underestimation of the burden of NZD has continually led to its further neglect in least developed countries such as Nigeria. Controlling zoonotic infections including NZDs in animals is crucial in reducing human infections. Veterinarians provides an understanding of the epidemiology of infectious diseases in animal population and are therefore integral for the overall reduction in global burden of NZDs worldwide. Due to the current lack of and in some cases weak involvement of Veterinarians in policy issues related to zoonotic diseases, there is need to elucidate their importance in NZDs control in Nigeria. This review therefore summarises the neglected zoonotic diseases so far documented in Nigeria and also highlight the important role of the Veterinarian in their prevention and control within both human and animal population. Important recommendations to strengthen the role of the public health Veterinarian for sustainable control of NZDs were made.

Bacillus anthracis Diversity and Geographic Potential across Nigeria, Cameroon and Chad: Further Support of a Novel West African Lineage

Zoonoses, diseases affecting both humans and animals, can exert tremendous pressures on human and veterinary health systems, particularly in resource limited countries. Anthrax is one such zoonosis of concern and is a disease requiring greater public health attention in Nigeria. Here we describe the genetic diversity of Bacillus anthracis in Nigeria and compare it to Chad, Cameroon and a broader global dataset based on the multiple locus variable number tandem repeat (MLVA-25) genetic typing system. Nigerian B. anthracis isolates had identical MLVA genotypes and could only be resolved by measuring highly mutable single nucleotide repeats (SNRs). The Nigerian MLVA genotype was identical or highly genetically similar to those in the neighboring countries, confirming the strains belong to this unique West African lineage. Interestingly, sequence data from a Nigerian isolate shares the anthrose deficient genotypes previously described for strains in this region, which may be associated with vaccine evasion. Strains in this study were isolated over six decades, indicating a high level of temporal strain stability regionally. Ecological niche models were used to predict the geographic distribution of the pathogen for all three countries. We describe a west-east habitat corridor through northern Nigeria extending into Chad and Cameroon. Ecological niche models and genetic results show B. anthracis to be ecologically established in Nigeria. These findings expand our understanding of the global B. anthracis population structure and can guide regional anthrax surveillance and control planning.

Anthrax, caused by the soil-borne bacterium Bacillus anthracis, is a disease with important public health and national security implications globally. Understanding the global genetic diversity of the pathogen is important for epidemiological and forensic investigations of anthrax events. Toward this, we describe B. anthracis genetic diversity in Nigeria and confirm it belongs to a unique West African genetic group not yet reported beyond neighboring Cameroon and Chad and Mali. This refines the global phylogeny of B. anthracis, allowing the development of more accurate diagnostics. We coupled these efforts with ecological niche modeling to map the geographic distribution of this strain group across the region. Suitable habitat for the pathogen is predicted across central Nigeria from west to east into Cameroon and Chad. Understanding the geography of B. anthracis plays an important role in informing public health by targeting disease control to high risk regions. This is particularly important in resource limited areas where intervention strategies are constrained and zoonotic disease risk is high.

Strongyloidiasis--an insight into its global prevalence and management

BACKGROUND

Strongyloides stercoralis, an intestinal parasitic nematode, infects more than 100 million people worldwide. Strongyloides are unique in their ability to exist as a free-living and autoinfective cycle. Strongyloidiasis can occur without any symptoms or as a potentially fatal hyperinfection or disseminated infection. The most common risk factors for these complications are immunosuppression caused by corticosteroids and infection with human T-lymphotropic virus or human immunodeficiency virus. Even though the diagnosis of strongyloidiasis is improved by advanced instrumentation techniques in isolated and complicated cases of hyperinfection or dissemination, efficient guidelines for screening the population in epidemiological surveys are lacking.

METHODOLOGY AND RESULTS

In this review, we have discussed various conventional methods for the diagnosis and management of this disease, with an emphasis on recently developed molecular and serological methods that could be implemented to establish guidelines for precise diagnosis of infection in patients and screening in epidemiological surveys. A comprehensive analysis of various cases reported worldwide from different endemic and nonendemic foci of the disease for the last 40 years was evaluated in an effort to delineate the global prevalence of this disease. We also updated the current knowledge of the various clinical spectrum of this parasitic disease, with an emphasis on newer molecular diagnostic methods, treatment, and management of cases in immunosuppressed patients.

CONCLUSION

Strongyloidiasis is considered a neglected tropical disease and is probably an underdiagnosed parasitic disease due to its low parasitic load and uncertain clinical symptoms. Increased infectivity rates in many developed countries and nonendemic regions nearing those in the most prevalent endemic regions of this parasite and the increasing transmission potential to immigrants, travelers, and immunosuppressed populations are indications for initiating an integrated approach towards prompt diagnosis and control of this parasitic disease.

Strongyloides stercoralis and the immune response

The immune system is a highly evolved network of cells and molecules that can distinguish between invading pathogens and the body's own cells. But helminths, in their complex forms, are capable of down-regulating host immunity, protecting them from being eliminated and also minimizing severe pathology in the host. This review focuses on Strongyloides stercoralis and the immune responses in immunocompetent and/or immunocompromised individuals. It also highlights the implications for diagnosis/treatment and draws attention to an emerging public health disease. The solution to reducing the prevalence of strongyloidiasis remains on the effectiveness of pre-emptive measures in endemic communities, increased awareness, prompt early diagnosis as well as timely treatment.

Neglected tropical diseases in sub-saharan Africa: review of their prevalence, distribution, and disease burden

The neglected tropical diseases (NTDs) are the most common conditions affecting the poorest 500 million people living in sub-Saharan Africa (SSA), and together produce a burden of disease that may be equivalent to up to one-half of SSA's malaria disease burden and more than double that caused by tuberculosis. Approximately 85% of the NTD disease burden results from helminth infections. Hookworm infection occurs in almost half of SSA's poorest people, including 40-50 million school-aged children and 7 million pregnant women in whom it is a leading cause of anemia. Schistosomiasis is the second most prevalent NTD after hookworm (192 million cases), accounting for 93% of the world's number of cases and possibly associated with increased horizontal transmission of HIV/AIDS. Lymphatic filariasis (46-51 million cases) and onchocerciasis (37 million cases) are also widespread in SSA, each disease representing a significant cause of disability and reduction in the region's agricultural productivity. There is a dearth of information on Africa's non-helminth NTDs. The protozoan infections, human African trypanosomiasis and visceral leishmaniasis, affect almost 100,000 people, primarily in areas of conflict in SSA where they cause high mortality, and where trachoma is the most prevalent bacterial NTD (30 million cases). However, there are little or no data on some very important protozoan infections, e.g., amebiasis and toxoplasmosis; bacterial infections, e.g., typhoid fever and non-typhoidal salmonellosis, the tick-borne bacterial zoonoses, and non-tuberculosis mycobaterial infections; and arboviral infections. Thus, the overall burden of Africa's NTDs may be severely underestimated. A full assessment is an important step for disease control priorities, particularly in Nigeria and the Democratic Republic of Congo, where the greatest number of NTDs may occur.

Human campylobacteriosis in developing countries

Campylobacteriosis is a collective description for infectious diseases caused by members of the bacterial genus Campylobacter. The only form of campylobacteriosis of major public health importance is Campylobacter enteritis due to C. jejuni and C. coli. Research and control efforts on the disease have been conducted more often in developed countries than developing countries. However, because of the increasing incidence, expanding spectrum of infections, potential of HIV-related deaths due to Campylobacter, and the availability of the complete genome sequence of C. jejuni NCTC 11168, interest in campylobacteriosis research and control in developing countries is growing. We present the distinguishing epidemiologic and clinical features of Campylobacter enteritis in developing countries relative to developed countries. National surveillance programs and international collaborations are needed to address the substantial gaps in the knowledge about the epidemiology of campylobacteriosis in developing countries.

Transporters in African trypanosomes: role in drug action and resistance

Sleeping sickness is an increasing problem in many parts of sub-Saharan Africa. The problems are compounded by the lack of new medication, and the increasing resistance against traditional drugs such as melarsoprol, berenil and isometamidium. Over the last few years, much progress has been made in understanding how drug action, and the development of resistance, is related to the mechanisms by which the parasite ingests the drugs. In some cases novel transporters have been identified. In other cases, transporters do not appear to be involved in drug uptake, and selectivity must lie with other parasite features, such as a specific target or activation of the drug. Lessons learned from studying the uptake of drugs currently in use may assist the design of a much needed new generation of trypanocides.