APOPO's HeroRAT's - An Efficient TB Detection Solution for High Burden Mega Cities

APOPO trains African Giant Rats or HeroRATs to save lives. APOPO focuses on placing trained HeroRATS into disease and threat detection programs that save lives.  APOPO takes animal welfare very seriously and no HeroRAT has ever been harmed while performing their life saving work. APOPO TB Detection Rats can screen sputum samples 40 times faster than a typical lab technicial in a high TB burden country with better sensitivity. 


At a Glance

Comments 1
Favorites 0
Evidence 0

How Can You Help?

  • Participate with research or a study
  • Provide resources, best practices, tool kits, research, data, etc
  • Public Speakers at Events
  • Connect us with funding and resources
  • Support our Government relations, policy and advocacy efforts

Point of Contact

About This Innovation

Innovation Stats

Funding Goal ($): 
What phase of development is your innovation currently in?: 
Potential Lives Impacted: 
Actual Lives Impacted: 
Potential Lives Saved: 
Actual Lives Saved: 
Cost Per Unit ($): 

Provide a status update for your Innovation.

Over the last 10 years, APOPO conceived and then developed a Tanzanian born tuberculosis (TB) scent detection technology that has improved TB detection in Tanzania since 2007 and in Mozambique since 2013. APOPO trains locally available giant African pouched rats (Cricetomys gambianus) to detect TB in human sputum samples. The detection rats complement the national TB programs by re-evaluating sputum samples from patients who were deemed TB-negative as tested in local public clinics. Because the rats are so fast a team of trained Giant Rats can easily screen more than 500 samples a day if operating at maximum capacity.

HeroRATs have the capacity to evaluate 100 sputum samples within 20 minutes. In comparison, a lab microscopy technician in Tanzania would take up to 4 days to perform the task by routine smear microscopy which has poor sensitivity. In collaboration with the National Tuberculosis and Leprosy Programs (NTLPs) of Tanzania and Mozambique, APOPO is improving case detection in 47 public clinics, covering 50% and 100% of all presumptive TB patients who present themselves at the clinics in Dar es Salaam and in Maputo, respectively. To date, APOPO has diagnosed 8,300 TB patients that were missed by the clinics, and has thereby increased the case detection in the clinics it works with by over 40%.

In addition to routine case finding as described above, APOPO has recently been awarded a USAID Development Innovation Ventures (DIV) contract to research the accuracy and cost effectivness of rat screening systems for active case finding among high burden prisons in Tanzania.  Because targeted active case finding in high burden popolation involves screening so many people, current methods are either too slow or too expensive to implement widely. The speed and low variable costs of APPOP's TB Rat detection systems potentially offers a a more affordable active case finding system for various high burden populations, including individuals living with HIV/AIDS, prisoners, and plantation and mine workers.

How does your innovation work?

APOPO's HeroRAT TB Detection system is part of an integrated system that works to maximize how many additional TB postive patients are found and then placed on life saving medication. This process below is similar in both Tanzania and Mozambique. 

Sample Collection and Processing: APOPO collects samples daily from clinics in Dar and Maputo, that routinely miss 50% of the actual positive TB patients that provide them with sputum samples. APOPO employs a trained liaison who travels to each clinic by motorcycle to collect samples into a cooler box fashioned onto the back of the motorcycle. This liaison copies from each clinic’s records the patient gender, age, and sample status (whether positive or negative) next to a unique sample number ID for each sample (see sample data sheet above). The liaison will ensure that samples are appropriately collected, labeled, and stored in the freezer.  
Rat Screening: On the day of rat evaluations, the samples are thawed and placed into an aluminum bar that holds 10 samples. This bar attaches to a cartridge under the floor of the rat screening cage and there is a hole above each sputum sample on the cage floor that is opened and closed. As the rat walks down the centerline of the cage, the trainer opens each hole to allow the rat to smell. The rat is trained by operant conditioning to pause over TB-positive samples and ignore negative samples. Those samples found positive by the TB-clinic technicians are used as reward samples and indications by the rats are followed with food. Those samples found negative by the technicians but positive by the rats are considered suspect for TB and then revaluated by LED microscopy in the next step.
New patient confirmation by LED Microscopy: Sputum samples that came in as negative from the TB centers but indicated as positive by rats will be confirmed by concentrated LED fluorescence microscopy (concentrated microscopy).  While the rats offer a tremendous advantage in diagnostic speed, they have a lower specificity than concentrated microscopy meaning they are prone to indicating samples as TB positive even when they are really negative. Therefore if APOPO made clinical decisions based solely off the rats it would give false positive patients TB drugs, encouraging the spread of the far more dagenrous Multiple Drug Resistant TB. Nevertheless the rat’s initial rapid diagnosis greatly limits the amount of sample that needs to be rescreened by microscopy ultimately resulting in a more cost effective and speedy algorith.
It is important to note that APOPO’s concentrated LED microscopy technique is far more accurate than the NTLP traditional microscopy. Because the whole process is centralized in a well maintained lab, rather than in decentralized and overburdened NTLP clinics, APOPO is able to ensure each microscopy screen is done by a specialized technician with a high performing microscope under tight quality contorls. APOPO also concentrates samples using sodium hydroxide before smear preparation (concentrated microscopy) which greatly increase sensitivity. This process, which would be far too expensive and complicated to do in decentralized NTLP clinics, as well as APOPO's specialized and well equiped technicians result in accuracy rates that are xxx% higher than an average NTLP microscopy technician.
Patient Notification: Patients who are confirmed positive by FM microscopy will be notified by the TB clinic. If the clinic cannot reach the patient which is normally the case, employees from local community based organization who have had TB themselves and are trained in educating community members on the efficacy of being treated for TV, track the patients. These specialists will first attempt to call individuals if a cell phone numbers is available. In the event that they are unable to reach the number of the individual, these specialists, whom normally comes from the same community as the diagnosed patient, will contact the neighborhood or village chief where the individual lives in an attempt to locate them. If they locate a patient who is initially hesitant to return to the hospital to begin treatment the specialist will share their personal storied battling TB, and then recovering from the disease which helps to compel numerous individuals to return to the clinics for treatment. By working with CBO's in Mozambique and Tanzania, APOPO and its NTLP partners are currently able to track and treat about 60% of the additional patients found by APOPO's TB screening system.


What Evidence do you have that your Innovation works?

Because APOPO is conducting a highly scientific detection task that is integrated into the detection programs of the National Tuberculosis Programs in both Tanzania and Mozambique, clear mathematical KPI's and indicators are built into every task. APOPO is participating in international European Quality Assurance programs from INSTAND-Germany and UK-NEQAS which includes a rigorous evaluation of the quality of our laboratory work and impact data. INSTAND evaluated APOPO in March 2014 and the organization scored 100% on all categories. 

In addition to its well documented and verified life saving impact, APOPO has conducted several peer review studies documenting the accuracy of TB Detection Rats. These can be found at https://www.apopo.org/en/contact/press/publications

Do you have current users or testers?

APOPO is an officialy recognized partner of the National Tuberculosis Program's in Tanzania and Mozambique. These government programs appreciate the fact that APOPO raised their case detection rats in Dar and Maputo, through a system that is completely univasive to their regular day to day functionings. When APOPO's HeroRAT screening algorithm confirms a formerly diagnosed TB negative patients as TB positive, they treat the patients as positive and offer them the routine course of free treatment.

APOPO currently covers 32 or half of the NTLP clinics in Dar Es Salaam. APOPO covers the whole city of Maputo, covering all 15 clinics.

What is your strategy for expanding use of your innovation?

APOPO's TB Detection Rat Algorithm currently has a diagnostic delay of 5 days which keeps APOPO and its partners from being able to treat almost every patient that APOPO uncovers. In order to remedy this problem APOPO is planning to transition to overnight screening in 2016. Because patients in many high burden countries are accustomed to going back the next day to get sputum microroscpy results, APOPO results will then be delivered at the same time as clinic results. Since over 95% of patients go back the next day to get results from the clinics, APOPO's end life saving impact will increase by over 50%.

By increasing the life saving impact of its screening algorithm, APOPO's cost effectivness and population level impact will improve, be easier to study, and be more obvious to donors. This will should open up doors for funding and partnerships that will allow APOPO to scale to additional High Burden TB megacities. APOPO already has string interest from National Tuberculosis Program Official in Ethiopia, Kenya, Bangladesh, Pakistan, and Cambodia and would like to set up a total two to three new programs in these countries by the end of 2018. This will ultimatley facilitate APOPO reaching its goal of screnning 1 million people by 2020.  


Next Steps

If APOPO is able to raise an additional $1M it will be able to execute on the following strategic objectives which should not only increase its short and mid term impact, but also facilitate long term scaling to at least 3 additional high TB burden mega cities in the next five years.


In Maputo, APOO’s lab is already located centrally in the city. Therefore APOPO will only need to cover the increased salary and logistical costs needed to transition to same day diagnosis. In Tanzania, APOPO currently conducts TB screening at its operational headquarter in Morogoro, a 4 hour car ride away from Dar. Therefore APOPO will need to build a new centrally located screening facility in Dar as well as cover increases in salary and logistical costs. 


Because it is a relatively small city of 2 million people, APOPO already covers all of the 15 NTP clinics in Maputo. Dar however, is much larger and more sprawling, with an estimated 5 million people. To serve the TB diagnostic needs of this more populated and spread out population, the Tanzanian NTLP has set up 32 clinics. With its current limited budgets and logistical constraints, due in part to having to transport samples to Morogoro for testing, APOPO is only able to work with 23 of these NTLP clinics. 

As it transitions to a centralized same day screening lab in Dar, APOPO should be able to scale to all of the NTLP clinics in Dar with a relatively modest investment in extra human and logistical resources. Covering all of the clinics will allow APOPO and the NTLP to immediately find and treat more patients. It will also strengthen the evidence of population impact studies because the effects of APOPO’s intervention can be more easily linked to city wide TB incidence data, ultimately making the intervention effect more credible to international development agencies. 


APOPO is currently best positioned to launch its next program in Addis Abbaba, which has TB incidence levels and a populations similar to Dar. Moreover APOPO's former TB Program Director is an Ehtiopian national who returned to the country and would be able to quickly implement the program after funding was recieved, with the goal of having a city wide, overnight screening operation up and running in a year. In addition to Addis APOPO is well positioned to launch a program in Nairobi and Phenom Phen. APOPO has also forged relationships with local stakeholders interested in launching a mega city screening program in Dhaka, Bangladesha or mega cities  in Pakistan.  Ultimatley lower costs and the huge populations and high TB incidence of these areas could facilitate an even lower cost per life saved than APOPO has in Sub Saharan Africa.


Since the launch of APOPO’s second line screening program, case detection in collaborating clinics has increased 45% due to the scent-detection rat technology developed by APOPO. This intervention may serve as a model for similar combined case finding interventions in other megacities. Nevertheless decisions by major donors to both scale up and continue to fund such interventions are greatly aided by independent peer reviewed estimates of their cost-effectiveness and anticipated impact on TB incidence and mortality in the population. Therefore as APOPO improves its impact with overnight screening and city wide coverage in Dar, Maputo, and potentially additinal mega cities, it should be in a better positional to engage indpendent researchers to confirm the improved cost effectivness and population impact numbers of its intervention.



This is so cool! Might want to check the link though, it doesn't seem to work.