Email: drbarshaofficial@gmail.com
ARTICLE:
Advancing Disease Mitigation: The Imperative for Japanese Encephalitis
Vaccination in Bangladesh
ABSTRACT:
Japanese Encephalitis (JE) is a viral disease caused by the Japanese
Encephalitis Virus (JEV) which is a mosquito-borne, single-stranded, RNA
flavivirus belonging to the Flaviviridae family. It is imperative to
note that JE can cause severe inflammation of the brain, leading to
long-term neurological complications or even death in some cases. JE
vaccine provides a crucial defense against this potentially fatal
disease. Given the high prevalence of JE in Bangladesh, widespread
vaccination campaigns and public health initiatives are necessary to
promote awareness and ensure that individuals at risk receive the
vaccine. The commentary emphasizes on how crucial it is that individuals
who are at risk of JE infection receive the vaccine through nation wide
immunization campaign in Bangladesh.
INTRODUCTION:
Japanese Encephalitis (JE) is a viral malady engendered by the Japanese
Encephalitis Virus (JEV), an RNA flavivirus of the Flaviviridae family,
transmitted by mosquitoes. The transmission of JE ensues through a
zoonotic cycle encompassing reservoirs, predominantly pigs, carriers
exemplified by water birds, vectors typified by mosquitoes, and humans,
deemed as dead-end hosts due to their low viremia levels post-infection
(1,2). The primary vector responsible for JE transmission is Culex
tritaeniorhynchus, with secondary vectors in the region including Culex
gelidus, Culex fuscocephala, and Culex annulirostris (3,4). The
incidence of JE evinces geographical disparities, with epidemic
proclivities observed in northern realms of Asia, such as Bangladesh,
Bhutan, the People’s Republic of China, Taiwan, and Japan, where the
disease exhibits temporal patterns. Conversely, JE is endemic in
southern domains such as Australia, Burma, Brunei Darussalam, and
Cambodia, where disease occurrences transpire sporadically throughout
the year (5).
RECENT JAPANESE ENCEPHALITIS STATUS IN BANGLADESH:
A systematic review conducted by Campbell et al. underscores the
vulnerabilities in the surveillance system and estimates the overall
incidence of JE in Bangladesh at 86,000 cases with 13,600 to 20,400
annual fatalities, predominantly afflicting regions with suboptimal or
negligible vaccination coverage (6,4). The inaugural outbreak of JE in
Bangladesh was documented in 1977, encompassing 22 cases and seven
mortalities. Subsequent surveillance and hospital-based investigations
have revealed an estimated incidence ranging from 0.6 to 2.7 per 100,000
individuals in Chittagong and Rajshahi (5). The risk cohorts for JE
primarily comprise denizens toiling in agrarian hinterlands with
pronounced rice cultivation and recurrent irrigation inundation. In
Bangladesh, JE infections evince higher prevalence in areas contiguous
to the endemic enclaves of India (7). The lion’s share of JE infections
manifest as either asymptomatic or manifest with mild symptoms, such as
pyrexia and cephalalgia. However, children under the age of 15 evince
heightened susceptibility to the ailment, often presenting with
gastroenteric distress and emesis (4). A severe manifestation of JE
befalls approximately one in every 250 patients, characterized by an
abrupt onslaught of fever, cephalodynia, myalgia, and anorexia,
succeeded by neuropsychiatric perturbations, comatose states, seizures,
and a case fatality rate of 30% among symptomatic sufferers (4,5).
Furthermore, protracted neurological and psychiatric sequelae,
encompassing paralysis, amnestic deficits, aberrant behavior, dysphasia,
and coordination abnormalities, bedevil approximately 20% to 30% of JE
survivors (2).
PREVENTION AND CONTROL MEASURES FOR JAPANESE ENCEPHALITIS:
Supportive management to palliate symptoms and optimize nutritional
status comprises the crux of JE therapeutics. Given the mosquito-borne
nature of JE, prophylactic measures such as the utilization of
pesticides and mosquito nets, swine segregation and culling, and
vaccination campaigns for porcine populations are deployed. However,
human immunization stands out as the quintessential approach to curbing
disease burden (4).
Japanese encephalitis (JE) constitutes the preeminent
vaccine-preventable encephalitis in Asia (8). Four vaccine variants are
currently available: mouse brain-derived inactivated, cell
culture-derived live-attenuated, cell culture-derived inactivated, and
genetically engineered live-attenuated chimeric vaccines (9). Each
vaccine necessitates 2 to 3 primary doses along with subsequent boosters
administered according to distinct schedules (10). According to the WHO
surveillance in 2016, JE vaccination has already been implemented in
neighboring countries such as India and Nepal, initially in response to
epidemiological outbreaks in various regions, and has now become a part
of their national immunization programs targeting the 1-15 years old
population (11,12,13). While financial and logistical constraints
persist, UNICEF and Gavi continue to provide support to endemic
countries, assisting them in integrating JE vaccination into their
national immunization strategies. However, Bangladesh has yet to seize
this golden opportunity, likely due to several challenges within its
healthcare system, including a shortage of healthcare workers and
inadequate infrastructure in rural areas, which hamper vaccine
administration and the monitoring of its efficacy in disease prevention.
The majority of JE cases (80%) occur between July and November, during
the monsoon and post-monsoon seasons (14). Furthermore, compared to
other regions, the case fatality rate in the Rajshahi region of
Bangladesh surpasses that of northwestern areas (15). It is imperative
to highlight these specific areas and devise robust management protocols
to effectively control and prevent potential outbreaks. The Centers for
Disease Control and Prevention (CDC) also recommend JE vaccination for
individuals traveling to Bangladesh. When prioritizing vaccine
introduction in Bangladesh, healthcare professionals have identified
five major qualitative criteria, including the incidence rate of the
disease, case fatality rate, vaccine efficacy, size of the population at
risk, and type of population at risk, along with two quantitative
criteria, weighting and scoring, to analyze and establish a vaccine
priority list (16). The incidence rate and case fatality rate criteria
carry substantial weight, underscoring the significance of disease
burden in the selection process. Considering these parameters, JE
vaccination emerges as the top priority in Bangladesh.
In light of annual outbreaks during the monsoon season and the
heightened risk of contracting this viral disease, particularly among
those residing in or traveling to rural areas, individuals working with
animals, or spending substantial time outdoors, it is imperative that
comprehensive vaccination campaigns and public health initiatives be
implemented to raise awareness and ensure that individuals at risk
receive the vaccine. Furthermore, vaccination should be administered at
least two weeks prior to potential exposure to the virus to ensure
optimal protection. Numerous considerations and implementations must be
undertaken from the grassroots level. Strengthening the surveillance
system in tertiary hospitals is crucial for accurately assessing the
burden of JE. Given the safety and affordability of current vaccines,
policymakers should spearhead mass vaccination programs in regions
burdened by the disease. Additionally, the government should conduct
awareness programs targeting the general public and healthcare workers
to eradicate the disease and facilitate early detection. Adequate
vaccine logistics, including robust cold chain capacities and effective
programmatic solutions, should also be promptly addressed.
CONCLUSION AND RECOMMENDATION:
In summary, JE vaccination is an imperative health intervention that can
substantially alleviate the burden of this disease in Bangladesh. Urgent
action and advocacy are necessary to promote JE vaccination in the
country.
CONFLICT OF INTEREST:
The authors declared no conflict of Interest.
SOURCE OF FUNDING:
None
ETHICAL APPROVAL STATEMENT:
Not Applicable