Itec bioterrorism
Emerging Infectious Diseases in Madagascar
Lina Ghulam Hassan, Linda Rivera Matsuo, Timothy Wells
Topics of Discussion
Background Information About Madagascar
Human Emerging Infectious Diseases
Animal Emerging Infectious Diseases
Plant Emerging Infectious Diseases
Public Health Laws In Preparation/Response to These EIDs
Medical & Non-Medical Countermeasures Available
Why Are These EIDs A Cause of Concern?
Courses of Action
Conclusion
Background Information About Madagascar
Madagascar lies off the southeast coast of Africa. More than nine-tenths of the population is Malagasy. Madagascar is a mostly unregulated economy with a variety of untapped natural resources. The country struggled with quality education, healthcare, and economic growth (CIA, 2018).
Deforestation is a serious issue, with much of the deciduous and evergreen forest cut for rice fields, for building materials and fuel, and for resource export (Southall, 2020).
The island is relatively isolated, creating a unique zoological balance. About 40 species of lemurs are indigenous to Madagascar. The coelacanth inhabits offshore waters (CIA, 2018).
Madagascar is divided into roughly 20 ethnic groups, making it incredibly diverse. There are no capital markets, a relatively weak judicial system, and rampants government corruption (Southall, 2020). Agriculture accounts for more than 25% of the GDP and employs about 80% of the country’s population. Erosion is a serious environmental problem. There exists hedgehog-like insectivores (tenrec) that have evolved only here. There’s a huge variety of birds (guinea fowl, partridges, pigeons, herons, ibis, flamingos, egrets, cuckoos, Asian robins) and about 800 species of moths, spiders, and butterflies (CIA, 2018).
Human Emerging Infectious Diseases
Human cases of the Bubonic Plague have been seen in Madagascar since 1898, after vaccination campaigns and improved hygiene plague was controlled in the 1950s, however since 1989 the number of cases has been steadily increasing (Chanteau, Ratsifasoamanana, Rasoamanana, Rahalison, Randriambelosoa, Roux, & Rabeson, 1998).
This is an important disease to discuss because of the severity of the disease for this entire country. The disease spreads rapidly and appears in approximately 3 to 4 per 100,000 inhabitants, and the mean annual death rate is 20% of the confirmed cases (Chanteau, et al., 1998).
Madagascar is an important case study involving plague because there are clear timelines and spikes of the disease. In 1898 the plague was brought to the island by steamboats from India and has never disappeared (Chanteau, 1998). The island successfully subdued the disease, only to have it spike in 1989, and again in 2017.
Background Information for Plague
Plague, a disease caused by Gram-negative bacillus Yersinia pestis, has been linked to three major historical pandemics with devastating impacts on human populations (Randremanana, et al., 2019). Bubonic plague is the most common form, which can develop into secondary pneumonic plague through septicaemic spread, and is capable of interhuman transmission (Randremanana, et al., 2019). The plague is an extremely devastating disease that spreads quickly and has high rates of fatality. Bubonic plague is acquired through flea bites that serve as vectors between reservoirs and humans (Randremanana, et al., 2019).
At the time of this epidemiological study, Madagascar accounted for 75% of plague cases reported to WHO globally, with an annual incidence of 200-700 cases (mainly bubonic plague) (Randremanana, et al., 2019). This high percentage should lead the WHO and other health organizations to question why this disease continues to reemerge and flourish in this country.
Plague Characteristics
Bubonic plague cases are characterized by fever and painful lymphadenitis around the area of the flea bite (Randremanana, et al., 2019).
Pneumonic plague cases are characterized by sudden fever, cough, and symptoms of lower respiratory tract infections (Randremanana, et al., 2019).
Case fatality rates have remained high, at about 10% and 40% in previous plague epidemics (Randremanana, et al., 2019).
Plague characteristics are important to understand and recognize because prompt treatment is the most effective method to subdue the disease. In addition, with prompt treatment, the common form (bubonic plague) is not given a chance to spread and potentially develop into pneumonic plague. With fatality rates as high as 40% this disease has devastating effects on the human populus that are exposed.
Public Health Measures & Medical Countermeasures
Madagascar has a devoted National Plague Control Program that requires every suspected case of plague to be reported to the Ministry of Public Health’s Central Plague Laboratory (Institut Pasteur, 2019). Madagascar is extremely devoted to the response and treatment of the plague.
In addition to the dedicated government programs and laboratories Madagascar also incorporates other methods to control the disease. Madagascar employs surveillance and vaccination efforts to decrease the number of cases of infectious diseases (NewsDesk, 2020).
The Central Plague Laboratory is where all clinical and epidemiological information is recorded, and where suspected cases are confirmed by laboratory tests (Institut Pasteur, 2019).
Madagascar not only has dedicated laboratories and mandatory reporting of plague cases to the National Plague Control Program, it also uses vaccination and surveillance efforts to curtail the spread and indoctrination of plague. Recently these programs have kept the number of plague cases relatively small. From August to November 2019 only 179 plague cases have been reported in 19 districts, with a majority being bubonic form (164 cases) (NewsDesk, 2020).
Why Others Should Care about Plague in Madagascar
In 2020 the world has never been more connected than it is currently. Trade and travel among nations is commonplace, and opposite corners of the Earth are accessible to anyone. The world as a whole needs to be concerned with the plague epidemics in Madagascar because there is a constant threat of the disease spreading. In 2017, an unprecedented outbreak occured when an infected individual traveled by bush taxi from the Central Highlands to the port of Toamasina, causing nearly 2,500 reported or suspected cases of plague (Institut Pasteur, 2019). This outbreak highlights the risks of reemergence and rapid spread of pneumonic plague in urban areas (Institut Pasteur, 2019). This disease is capable of suddenly, and violently, reemerging and quickly spread to a full blown epidemic swiftly.
The unprecedented outbreak of plague in 2017 highlights the threat of this disease to not only Madagascar, but the entire world. The disease spreads rapidly in urban areas, and there is nothing stopping an infected individual from traveling abroad instead of within Madagascar. If an infected individual travels outside Madagascar the disease could ravage entire countries because of its ability to spread quickly and the lack of vaccinations available because the disease is considered eradicated in most parts of the world.
Figures from the 2017 Plague Outbreak
The figure shown represents the number of confirmed, probable, and suspected plague cases in Madagascar from 1 August through 22 November 2017 (WHO, 2017). As seen in the figure the number of cases dramatically increased around September 30th. This is another demonstration of the seriousness of this disease and why not only Madagascar should take it seriously, but the entire world.
Courses of Action
The first recommendation is to administer vaccines throughout the country regularly. As seen in the 2017 case the disease can spread rapidly, but if the entire country is vaccinated it will greatly mitigate the spread and negative effects of the disease.
The second recommendation is to increase surveillance and epidemiological funds and efforts. Surveillance, along with vaccinations, have already proven to be effective in stemming the spread and prevalence of plague. With additional funds and resources surveillance can be increased which will stop the spread and identify the source of the outbreak much faster.
The WHO has previously responded and is given reports on outbreaks of plague in Madagascar. The third recommendation is to increase the presence of WHO doctors and workers during the months of September and April in which seasonal upsurges of plague occur. The WHO presence will work to stem outbreaks, and assist in administering vaccines.
The three provided recommendations are based on previously effective methods of stopping or slowing the outbreak of plague. Vaccines and surveillance techniques have been tried and proved effective, however, the plague continues to reemerge. With an increased effort in both vaccinations and surveillance the country may be able to eradicate the disease fully. With WHO assistance in the “plague season” the negative consequences will be mitigated or even fully eradicated.
Animal Emerging Infectious Diseases
Monkeypox is a disease that affects animals and it is similar to smallpox. Monkeypox is a viral disease that affects both people and animals. The animal affected by monkeypox includes rapids and rodents. The whole range of animals affected by this disease is still not known. However, both domestic and wild animals are susceptible to the disease.
The disease causes death to small rabbits. Some of the animals are kept for financial purposes and this leads to effect on the economy. Some people who rely on rabbits for meat lacks something to eat.
Monkeypox is one of the zoonoses emerging as infectious diseases in the community today. It is affecting the ministry of health since some of the disease are transferred from animals to people. Monkeypox can only be reduced through enforcement of laws that calls for vaccination of disease
Disease Characteristics
Monkeypox spreads from infected to uninfected animals through direct contact. This can be done through skin abrasions
In addition, monkeypox can be spread from one animal to another through air in aerosols. When it comes to non-human primates, monkeypox is normally a rash that lasts for 6 weeks. It can be viewed over the entire body though is mostly viewed on the face, limbs, palms, soles, and tails. Death does not occur all the time but is seen in infant animals. Some animals can be infected with the infection however, show no signs of illness.
Rabbits and rodents shows signs like fever, reddened eyes, runny nose, cough, swollen glands, depression, and loss of appetite, and minor swelling with pus and patchy hair loss.
Direct contact can lead to spreading of the disease. Avoiding exposure to rabbits and rodents can keep you away from the disease. The disease can be troublesome when having many rabbits within one place. Vaccination is highly required to reduce spread of diseases.
Public Health Laws In Preparation/Response to These EIDs
Medical & Non-Medical Countermeasures Available
Why Are These EIDs A Cause of Concern?
Courses of Action
Plant Emerging Infectious Diseases
Rice yellow mottle virus (RYMV) was first reported in Madagascar in 1989 and is currently considered one of the most important diseases of rice on the island. It is prevalent in the lowlands of the Northwest, where high yield reductions occur each year. A particularly devastating disease, RYMV can cause losses that exceed 90 % (Food and Agricultural Organization of the United Nations, 2020)..
Four insect RYMV vectors have been identified so far - three beetles of the Chrysomelidae family (the two rice hispa Dicladispa gestroi and Trichispa sericea, and Chaetocnema pulla) and one grasshopper, Oxya sp. Based on patterns of this virus epidemic, Dicladispa gestroi has been labeled the biggest vector responsible (Abubakar et al., 2003).
RYMV is transmitted easily via sap transmissible as well. This plays an important role in the epidemiology of the disease in this region. From the three rice seasons grown in Northwest Madagascar, the rice of the rainy season suffers most from RYMV. The existence of infected stubble and ratoon of the intermediate season allows the first rice hispa that appear after diapause to become infectious. This vicious cycle makes RYMV particularly dangerous (Masajo, John, & Thottappilly, 1988).
Rice Yellow Mottle Virus [Digital image]. (n.d.). Retrieved October 16, 2020, from https://www.sciencepicture.co/images/3316/Rice-Yellow-Mottle-Virus.html
Disease Characteristics
The disease is characterized by yellow or orange leaf discoloration, stunting, sterility and empty spikelets Non-synchronous flowering and death of plants occur and grain discoloration is noticed in the field (Rakotomalala, 2013)..
Infection by RYMV is systemic, affecting the entire plant and causing leaf yellowing of varying intensity, mottling, necrosis and stunted growth. Tillering is reduced, with a weakening of the plant, partial emergence of panicles and spikelet sterility (Reckhaus & Andriamasintseheno, 1997).. Symptom expression are influenced by light intensity, day length, humidity, temperature and growth stage of the plant, among other factors (Bakker, 1970)..
Plants of highly susceptible cultivars may die following severe infection. Symptoms of the virus consist of a linear chlorotic mottle which later spreads into broken or continuous pale-green to yellowish streaks up to 10 cm long. Young seedlings are most susceptible to infection (Bakker, 1970). The first newly formed leaves are spirally twisted and have difficulty in emerging. Infected plants exhibit delayed flowering with poorly exserted panicles bearing sterile and discoloured spikelets (Bakker, 1974).
[Standard evaluation system (SES) for RYMV symptoms. 1 = no symptoms, 3 = leaves green but with spare dots or streaks and less than 5% of height reduction, 5 = leaves green or pale green with mottling and 6 to 25% of height reduction, flowering slightly delayed, 7 = leaves pale yellow or yellow and 26–75% of height reduction, flowering delayed, and 9 = leaves turning yellow or yellow orange, more than 75% of height reduction, no flowering or some dead plants.]. (2014). Retrieved October 16, 2020, from https://www.researchgate.net/figure/Standard-evaluation-system-SES-for-RYMV-symptoms-1-no-symptoms-3-leaves-green-but_fig2_272784931
International Response to Rice Yellow Mottle Virus
The Food and Agriculture Organization of the United Nations has partnered up with Madagascar and China to take active steps to be ensure Madagascar is self-sufficient with their rice supply by the end of 2020 by introducing a greater-yielding rice into crop circulation and providing harvest training (Food and Agriculture Organization of the United Nations, 2020).
Madagascar’s Ministry of Agriculture, Livestock, and Fishery have participated in the trainings and worked to disseminate the information.
The new kind of rice seeds are better suited to the Malagasy subtropical climate, which consists of a hot and rainy season between November and the end of March and a cooler dry season from May to October. This Weichu rice variety has been especially developed to fit the climatic and soil conditions of Madagascar. The project aims to train at least 1 000 farmers, in order to bring the average rice yield up from 2.8 tonnes per hectare to between 8 and 12 tonnes (USDA Foreign Agricultural Service, 2017).
Medical & Non-Medical Countermeasures Available
Madagascar has tried to combat RYMV through prevention and damage control.
Funding and resources have been channeled towards the creation and distribution of resistant and tolerant varieties. The use of nursery sites and direct sowing into uninfected fields stunts the spread of the virus. In order to avoid the insect vectors as much as possible, planting early in the peak season is highly recommended. Synchronizing the planting so that the virus doesn’t spread from mature to younger crops is also recommended (Southall, 2020).
Damage control is in the form of recognizing the signs of the virus and eradicating the infected plants.
Weed control, pesticides, proper sanitations with irrigation and farm machinery have also been exercised .It has also been recommended to reduce the application of fertiliser on infected plants. There are no chemical control methods to directly stop the spread of RYMV (Food and Agriculture Organization of the United Nations, 2020).
Why is RYMV A Cause of Concern?
Madagascar’s battle with RYMV poses a unique and extreme threat to the rice crop for the native people of Madagascar as well as other nations that depend on that supply. The nature of RYMV makes all regions of rice growth susceptible - lowland, rainfed upland, swamp, irrigation paddies, and even deep flooded regions (Raymundo & Buddenhagen, 1976)..
So far the reported yield loss in Madagascar is 84-97%, exceeded the loss rates in other African nations like Niger, Kenya, Sierra Leone, and Liberia substantially.
Even with this consistent threat and loss, Madagascar’s 2017/18 rough rice production is estimated at 3.5 million metric tons (USDA, 2017).
Traditional African rice varieties, adapted to upland conditions are significantly more tolerant and appear to possess a higher level of resistance to RYMV, regardless of origin, than exotic lowland cultivars (Raymundo and Konteh, 1980).
Almost 30% of Madagascar's GDP is generated by rice. More than 70% of Malagasy people work in agriculture, thereof more than the half on rice fields. The latter make up 40% of the country's cultivated areas.
Courses of Action
First course of action would be to continue research to develop a spray or soil treatment that could actively combat RYMV in plants that are already infected. The current ways to curtail the spread of this virus are physical relocation of the infected, and yet the country is still being ravaged by this disease. Immunological typing and phylogenetic analysis is actively being done with RYMV to study the attack mechanism.
A second course of action would be to increase the surveillance of the spread of the virus. There is already a lot of information known about trends and tendencies of RYMV, but by continuing to track the spread, researchers may be able to uncover a key piece of information that could better prepare the people of Madagascar for the seasonal fluxes of mass RYMV infection.
There are resistant and tolerant varieties of rice being distributed to combat the spread of RYMV. There needs to be more funds towards this endeavor and these durable strains need to be more widespread and available to anyone growing rice in Madagascar.
The success of all these courses of action depends heavily on coordination between the government and the communities.
Conclusion
All three of these emerging infectious diseases are causes of concern for the people of Madagascar, the Madagascar government, and the international public health community.
The World Health Organization and United Nations have devoted time and resources to aid Madagascar in the fight against these EIDs, as they have begun to or have the potential to cripple social and economic status as well as conservation efforts.
Bibliography
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