A Bite that Kills - Mosquito Related Diseases in India
An ASAR Data Story
By ASAR Blog Team
Ideation & Drafting
Madhurima V, Pratik Gavhane, Parth Sharma
Calculations & Visualisations
Pratik Gavhane, Parth Sharma, Siddhesh Zadey
Review & Editing
Parth Sharma, Siddhesh Zadey
“The doctor of the future will give no medication but will interest his patients in the care of the human frame, diet and in the cause and prevention of disease.”
-Thomas A. Edison
India has a massive burden of vector-borne diseases - malaria, dengue, chikungunya, Japanese encephalitis, kala-azar, and lymphatic filariasis among several others. Around 95% of people live in malaria-endemic areas and dengue is prevalent in the entire country. The National Vector-Borne Disease Control Programme (NVBDCP) was launched in 2003-2004 to control the spread of these diseases.
Deaths due to these diseases are preventable by spreading awareness and effectively monitoring programmes, like NVBDCP, that implement ground-level prevention strategies. In this ASAR Data Story, using publicly available data from NVBDCP website, Ministry of Health and Family Welfare, Government of India, we focus on the magnitude of three vector-borne diseases: malaria, dengue, and filariasis, and assess the impact the NVBDCP has had on controlling them.
1. How has the magnitude of malarial illness changed in India over the past few years?
India recorded nearly 1.6 lakh malaria cases and 90 malaria deaths in 2021 accounting for 1.7% of malaria cases and 1.2% of deaths, globally. But independent researchers have estimated the actual number of cases to be 4 times and deaths to be 93 times more than what was reported by NVBDCP. Despite having questionable reliability, the available data helps us in monitoring the ongoing progress of malaria control in India.
The NVBDCP surveillance of malaria monitors Slide Positivity Ratio (SPR). SPR is the number of laboratory-confirmed malaria cases per 100 suspected cases examined. It is considered a reliable metric to track malaria occurrence and predict malaria transmission. Malaria cases in India have reduced by 62.4% and deaths by 6.25% in the past 4 years. However, it is still a major public health problem.
Fortunately, over the past 4 years (2018-21) most states have controlled malaria well as seen through the SPR numbers (Fig 1). Uttarakhand, Arunachal Pradesh, Meghalaya, Assam, and Punjab were able to reduce their malaria burden (i.e. SPR) by more than 90%. However, an increase in burden was seen in Maharashtra, West Bengal, and Mizoram.
2. Is the National Vector-Borne Disease Control Programme (NVBDCP) monitoring malaria effectively?
The National Vector-Borne Disease Control Programme (NVBDCP) prescribes that the annual blood examination rate (ABER, which is the number of slides examined per 100 people in the population) for malaria should be at least 10%. ABER represents the coverage of surveillance programs.
According to NVBDCP, in 2021, only 14 Indian states/UTs had ABER greater than 10% (Fig 2). Seventeen states had ABER less than India’s average of 8.39%. Delhi recorded the lowest ABER of 0.20% and Mizoram the highest value (24.04%). Uttar Pradesh and Bihar recorded low caseloads (25 and 21 confirmed cases per 10,000 people examined, respectively) and had extremely low ABER (1.83% and 0.24%), indicating poor surveillance. Contrary to this, Mizoram and Tripura, two states with high caseloads (266 and 109 confirmed cases per 10,000 people examined, respectively) had the highest surveillance in the country (Fig 2).
3. How effectively has NVBDCP controlled urban malaria?
The Urban Malaria Scheme (UMS) is a programme introduced by NVBDCP for controlling malaria in 131 urban cities in 19 states and union territories (UTs) as nearly one-tenth of all malaria cases are in these cities. UMS reduced malaria deaths from 96 in 2005 to 0 in 2021 in the included cities. The SPR also fell from 2.33 to 0.59, over these years (Fig 3).
4. How well has dengue control been in India?
The number of diagnosed dengue cases has nearly doubled in 2021 (193,245 cases) compared to 2015 (99,913 cases). The reported deaths have increased by 57.3% (346 deaths in 2021 vs. 220 deaths in 2015). In 2021, cases and deaths had the highest recorded numbers since 2015 (Fig 4). This could be due to climate change as mosquitoes multiply faster in hotter climates. Urbanisation could also explain increased outbreaks as it has led dengue to spread all around the country and led to an increase in breeding places at the same time. A fall in cases in 2020 might be due to underreporting during the COVID-19 pandemic.
5. Which states have the most dengue cases and do they have enough surveillance?
India has 769 sentinel surveillance hospitals (SSHs) scattered throughout the country, established in 2007 to control dengue. SSHs are equipped with diagnostic test kits provided by the National Institute of Virology, Pune. In 2021, a low dengue case burden was reported in Bihar and Jharkhand - 5 and 6 cases per 10 lakh people, respectively. These low caseloads can be due to low surveillance capacity (Fig 5). For example, Bihar has 1 SSH per 136.8 lakh people while Jharkhand has 1 SSH per 38.5 lakh people. On the contrary, several UTs had 1 SSH for less than 6 lakh people - Delhi (5.9 lakh), Puducherry (3.1 lakh), and Chandigarh (1.3 lakh), but reported higher dengue cases per 10 lakh people, most likely due to better surveillance (Fig 5).
6. How far has India come in its mission to eradicate Filaria?
In 1997, the member nations of the World Health Organisation committed to eliminating lymphatic filariasis by 2020 through a resolution in the World Health Assembly(WHA) 50.29, which has now been updated to 2030. Filariasis is endemic to 257 districts in 21 states/UTs, and nearly 65 crore people were at risk of developing filariasis in 2019. Mass drug administration (MDA) was adopted as a strategy by India for lymphatic filariasis elimination with MDA observed in 151 (58.8%) of the 257 endemic districts in 2019.
In 2021, filariasis cases per 10000 people were greatest in Assam (690), followed by Gujarat (304), Madhya Pradesh (245), and Goa (179). While the states with the lowest burden nearing elimination were Telangana (6), Odisha (7), and Jharkhand (9) (Fig 6).
In summary, NVBDCP has been instrumental in controlling vector-borne diseases in India, but we still have a long way to go. This ASAR Data Story shows that low cases of dengue and malaria in certain states are not due to better control but due to poor surveillance. Even though malaria seems to be under control, the dengue burden is growing. Accurate data reporting and implementation of prevention and surveillance strategies along with better access to healthcare will help India control dengue outbreaks, and achieve global targets of reducing cases and deaths due to vector-borne diseases by 90%, and eliminate filariasis by 2030.
How to cite this article: Vuddemarry M, Sharma P, Gavhane P, Zadey S. A Bite that Kills - Mosquito Related Diseases in India [Internet]. Association for Socially Applicable Research (ASAR). 2022. Available from: https://www.asarforindia.org/post/a-bite-that-kills-mosquito-related-diseases-in-india