a possible connection between cholera in east africa and yemen. chironomidae are natural reservoirs and carriers of the vibrio cholerae bacterium. it has been suggested that adult chironomidae may aerially carry the bacterium between bodies of water, assisting in the transmission of cholera. based on this evidence, it is hypothesized that the el nino conditions over the gulf of aden may have contributed to the transmission of cholera from the horn of africa to yemen through wind effects on cholera-contaminated flying insects. health services and infrastructure collapse as of 2016, the government ended funding for public health, leaving many employees without salary. the impacts of the outbreak were exacerbated by the collapse of the yemeni health services, where many health workers remained unpaid for months. a months-long strike of sanitation workers over unpaid wages contributed to the accumulation of garbage that entered the water supply. qadri, islam and clemens write that the dramatic april 2017 resurgence coincided with heavy rains, and "was amplified by war-related destruction of municipal water and sewage systems". an international committee of the red cross (icrc) worker in yemen noted that april's cholera resurgence began ten days after sana'a's sewer system stopped working. raslan et al write in frontiers in public health:a failing sewage system, continued conflict and inadequate health care facilities are only a few of the reasons contributing to this problem. malnutrition, which is a significant consequence of the yemen war, has further contributed to this outbreak. rainy season epidemiological modelling of the outbreak from october 2016 to january 2016 together with satellite image-derived meteorological data showed that the rainfall had a strong impact in increasing the chances of transmission, with the rainy season of april 2017 having coincided with the onset of the second wave of the outbreak topping at more than 50,000 cases per week. the geography of yemen means that the western mountainous plateau sees more rainfall, and has therefore an increased risk of high cholera incidence due to water precipitations. lack of vaccination the international coordinating group on vaccine provision, which maintains vaccine stockpiles for cholera, announced a plan in june 2017 to send one million doses of oral cholera vaccine (ocv) to yemen, but this plan stalled. controversy surrounded whether vaccination was the best strategy, whether it was too late to start a vaccination campaign, whether there was enough stockpiled vaccine to meet worldwide needs, whether all of the reported cases of cholera in yemen were true cases as opposed to simply cases of diarrhea or other similar symptoms, and the effectiveness of the vaccine. the request for vaccine was retracted. in may 2018, the first ocv campaign in yemen was launched. the who and unicef delivered oral vaccines to 540,000 individuals in august 2018. federspiel and ali write in bmc public health:ocvs were not delivered until nearly 3.5 years into this humanitarian emergency, which has most likely been due to ongoing conflict, logistical circumstances, the scale of the epidemic, impairment of the humanitarian response by the parts to the conflict and some degree of negligence from donors, politicians and other decision makers. whatever the reasons, ocvs were not distributed until nearly 16 months into the cholera outbreak by which time more than a million cases had accumulated. neither were they in the two years of wash infrastructure breakdown that preceded the outbreak. this should serve as a historic example of the failure to control the spread of cholera given the tools that are available. today, "cholera outbreaks are entirely containable" (the lancet editorial, 2017). covid-19 pandemic the covid-19 pandemic in yemen is part of the worldwide pandemic of coronavirus disease 2019. as of 12 november 2020, there were 2,070 confirmed cases and 602 deaths. the covid-19 pandemic has further burdened the already overwhelmed healthcare system in yemen fighting a number of diseases including cholera, dengue fever, and malaria. only half of existing health facilities are fully functioning while more than 17.9 million people of a total population of 30 million need health care services in 2020. in addition, those that remain open lack medical personnel, basic medicine, and essential supplies such as masks and gloves. the lack of flights in and out of yemen to mitigate the pandemic has also restricted the movement of aid workers responding to the humanitarian crisis. humanitarian activity through 2018, several humanitarian healthcare organizations had reported activity to contain the cholera outbreak. the international committee of the red cross have supported 17 treatment centers with supplies including iv fluids, oral rehydration therapy supplies, antibiotics, chlorine tablets, in addition to sending engineers to help restore water distribution in yemen. the international rescue committee (irc) supplied seven hospitals with medicine and supplies, deployed health teams and trained volunteers, delivered health and nutrition services, and facilitated referrals of malnourished children. the world health organization coordinated the yemen health cluster with 40 member organizations, and together with health and water sanitation and hygiene (wash) units, explored the use of oral cholera vaccines (ocvs). the who reported operating 414 facilities using 406 teams active in 323 districts in yemen, which included 36 treatment centers for cholera. in the management of cholera, they stated that they trained 900 health workers and ran 139 oral rehydration locations, to treat 700,000 reported cases of the illness. unicef reported that they ran awareness campaigns with 20,000 promoters, provided water to more than one million individuals, served as the wash lead, and delivered "40 tons of medical equipment including medicine, oral rehydration solution, iv fluids and diarrhea kits". médecins sans frontières (doctors without borders) said it treated at least 103,000 individuals in 37 locations. global responses canada as of june 2, 2020, canada has pledged $40 million in humanitarian aid for yemen to help the politically unstable country cope with cholera, malaria, dengue fever, and diphtheria along with covid-19. this brings canada's total contributions to yemen since 2015 to $220 million, which contributes towards the goal of us$2.4 billion for underfunded humanitarian programs run by un agencies and humanitarian organizations in yemen. saudi arabia saudi arabia has been backing the yemen government in the fight against the houthi rebels, and they are also one of the top donors for un humanitarian aid operations in yemen. on 23 june 2017, saudi arabia's crown prince, mohammed bin salman, authorized a donation in excess of $66 million for cholera relief in yemen. mohammed al-jaber, the saudi ambassador to yemen, has announced half a billion dollars from saudi arabia to support un programs in 2020. united nations an aid conference was held in geneva in april 2017 that raised half of the us$2.1 billion that the united nations (un) estimated was needed. as of july 8, 2019, the un and partners are running 1200 cholera treatment facilities around the country, however, funding is an issue. the 2019 yemen humanitarian response plan required $4.2 billion to deliver assistance, but they ended up receiving $3.6 billion. for the 2020 plan, the un has so far received 15% of the necessary $3.5 billion needed. united states on april 3, 2018, the united states (u.s.) announced $87 million in additional humanitarian assistance to help the people of yemen, bringing the u.s. total assistance since 2017 to more than $854 million. this money will be used for food assistance, safe drinking water, emergency shelter, and medical supplies. the u.s. is also planning to provide $55 million in economic and development assistance, including programs to support livelihoods, rebuild infrastructure, and restore access to education. on march 27, 2020, the trump administration cut $70 million in assistance destined for northern yemen, framing the decreased funding as a response to the interference of houthi rebels. the u.s. officials were concerned that the assistance was directed to fighters instead of civilians. south yemen, which is less populous, still received aid dollars. united kingdom the united kingdom (uk) government has been one of the largest humanitarian donors to yemen, budgeting £139 million in 2017/2018 and earmarking £8m from the yemen budget specifically to respond to cholera. the uk has partnered with organizations including unicef and the international organisation for migration (iom) to combat the cholera disease in yemen. the uk's humanitarian response includes nutrition support, clean water, sanitation, and medical supplies, such as chlorine tablets and hygiene kits. the uk department for international development (dfid) has also worked with the met office, nasa and u.s. scientists to deploy a model to predict and effectively respond to outbreaks of cholera. dfid secretary priti patel has urged the international community to follow the uk government's steps to curb the cholera outbreak. world bank on august 25, 2017, the world bank announced $200 million u.s. to support yemen as it struggles to contain the cholera outbreak. this money is being used to strengthen the country's health, water, and sanitation systems. statistics the who provided regular outbreak updates for the epidemic in yemen up until august 2020. since then the epidemic has declined in numbers of cases and deaths, with 2020 seeing a total of 230,540 suspected cases and 84 deaths and 5,676 suspected cases with two deaths between january 1 and march 6 of 2021 furthermore, unicef reports that in 2021 over 190,000 children received a cholera vaccine, achieving 94% coverage. date suspected cholera cases cholera-related deaths source 2016-10-10 11 0 2016-10-13 186 0 2016-10-23 644 3 2016-10-30 1,410 45 2016-10-31 2,241 47 2016-11-06 2,733 51 2016-11-17 4,825 61 2016-11-24 6,119 68 2016-12-01 7,730 82 2016-12-08 8,975 89 2016-12-13 10,148 92 2016-12-28 12,733 97 2017-01-10 15,468 99 2017-01-18 17,334 99 2017-02-26 20,583 103 2017-03-07 22,181 103 2017-03-21 23,506 108 2017-04-27 26,070 120 2017-05-20 49,495 362 2017-06-10 96,219 746 2017-06-15 140,116 989 2017-06-22 185,301 1,233 2017-06-29 224,989 1,416 2017-07-06 275,987 1,634 2017-07-18 351,045 1,790 2017-07-27 408,583 1,885 2017-10-26 862,858 2,177 2017-12-19 1,009,554 2,345 2018-01-18 1,061,746 2,364 2018-02-01 1,072,744 2,368 2018-03-01 1,089,856 2,378 2018-04-05 1,112,175 2,391 2018-05-03 1,116,350 2,395 2018-05-20 1,126,790 2,411 2018-07-01 1,141,448 2,430 2018-09-23 1,233,666 2,630 2018-10-21 1,291,550 2,604 2018-11-11 1,303,839 2,614 2018-11-25 1,317,319 2,625 2018-12-09 1,329,285 2,641 2018-12-16 1,341,020 2,666 2018-12-30 1,350,139 2,682 2019-01-06 1,359,279 2,694 2019-01-13 1,367,849 2,703 2019-01-20 1,376,488 2,708 2019-02-03 1,383,907 2,716 2019-02-17 1,390,625 2,724 2019-04-07 1,420,393 2,775 2019-04-14 1,448,233 2,823 2019-04-28 1,470,735 2,873 2019-05-05 1,488,906 2,886 2019-05-12 1,505,610 2,898 2019-05-19 1,522,437 2,916 2019-05-26 1,539,305 2,928 2019-06-02 1,555,073 2,944 2019-06-09 1,572,731 2,955 2019-06-16 1,592,995 2,970 2019-06-23 1,613,872 2,989 2019-06-30 1,635,737 3,002 2019-07-07 1,657,286 3,020 2019-07-21 1,676,745 3,031 2019-07-28 1,694,765 3,045 2019-08-04 1,711,380 3,055 2019-08-11 1,727,688 3,069 2019-08-18 1,743,984 3,077 2019-08-25 1,761,482 3,089 2019-09-01 1,780,028 3,099 2019-09-29 1,796,653 3,114 2019-10-06 1,813,480 3,127 2019-10-13 1,827,904 3,143 2019-10-20 1,842,251 3,151 2019-10-27 1,855,175 3,161 2019-11-03 1,864,556 3,167 2019-11-10 1,875,918 3,170 2019-11-17 1,887,449 3,174 2019-12-01 1,898,236 3,176 2019-12-22 1,907,658 3,178 2019-12-29 1,916,811 3,181 2020-01-05 1,925,087 3,184 2020-01-12 1,932,798 3,188 2020-01-26 1,940,893 3,192 2020-05-17 1,944,360 3,192 2020-05-24 1,946,84 3,192 2020-05-31 1,949,920 3,192 2020-06-07 1,953,033 3,194 2020-06-14 1,956,124 3,198 2020-06-21 1,959,308 3,198 2020-06-28 1,962,357 3,199 2020-07-12 1,965,664 4,001 2020-07-19 1,968,536 4,001 2020-07-26 1,971,551 4,001 2020-08-02 1,973,697 4,002 2020-08-16 1,975,403 4,002 2021-04-30 5120 3 starting in december 2017, the world health organization began counting cases of cholera from 27 april 2017 onwards instead of from october 2016. this is resolved by adding 26,070 suspected cholera cases and 120 deaths from december onwards. starting on 8 november 2018, the world health organization began counting cases of cholera from 1 january 2018 onwards instead of from 27 april 2017. this is resolved by adding 1,048,701 suspected cholera cases and 2358 deaths from 21 october onwards.